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Optimization of the ion extraction from an inductively coupled plasma (ICP) by IBSimu modeling. Questo lavoro di tesi Ё nalizzato a raggiungere una pi№ profonda comprensione del processo di estrazione di un fascio di ioni da un Inductively Coupled Plasma accoppiato a uno spettrometro di massa (utilizzato per l'analisi di soluzioni radioattive). In particolare, lo studio Ё stato focalizzato sulla plasma torch e sull'extraction interface - costituita da sampler e skimmer. Per capire i processi che avvengono tra lo skimmer - a valle del quale il plasma perde la sua quasi-neutralit - e la prima lente ottica, Ё stato utilizzato IBSimu, un software appositamente creato per simulare l'estrazione di ioni ed elettroni da una sorgente di plasma. As said in the previous section, nowadays one of the most important meth- ods in atomic spectrometry is the arthur devany ICP-MS: the two main reasons for creative writing essays gcse, its success are the true multi-element capabilities and the extremely low detec- tion limits. All ICP sector eld instruments consist of : їЅ' an ion source (see chapter 3 for a detailed description); їЅ' a sampling interface (see chapter 4 for a detailed description); їЅ' an electrostatic lens system, used to guide, focus and accelerate the positively charged ion beam onto the entrance slit and to shape the beam, giving it a more rectangular prole (in accordance to devany, the ge- ometry of the persuasive essay entrance slit); їЅ' a magnetic sector, which bends ions according to their momentum; the electromagnet is typically operating in static mode (that is, at a constant eld) and the eld strength can be changed varying the electric current; їЅ' an electric sector, where dierences in ion energies are compensated to a certain extent; їЅ' a curved ight tube, between the poles of the electromagnet; їЅ' an entrance and an exit slit, to shape the geometry of the ion beam and to achieve a good resolution (which depends on the width of the incident ion beam and thus on the width of the entrance slit) ; їЅ' zoom and/or lter optics: in the Neptune, a zoom lens and an en- ergy lter, in order to maintain the direct guidance of the incoming ion beams into the detector and to permit ions with suciently high kinetic energies to pass only; їЅ' a detection system, consisting - in devany essay the Neptune - of a number of Fara- day detectors, arranged along the persuasive tools focal plane to devany essay, measure all isotopes of interest simultaneously; in addition, there are also electron mul- tipliers, discrete dynode detectors and channeltrons to monitor low isotopic abundance nuclides; їЅ' a vacuum system, otherwise the ions would scatter and there would be a signicant loss of transmission and sensitivity (see later for writing essays gcse, more details about dierent pressure regions). It has to be underlined that two dierent congurations are possible; in the studied case the plasma source and the extraction interface are grounded, as ions are accelerated by the lens system potential. Other instruments have the opposite arthur conguration, with the ion acceleration provided by the 8 Figure 2.5: Schematic drawing of the creative essays gcse Neptune MC-ICP-MS (Thermo Sci- entic) . interface, posed at a high voltage. The disadvantage of this solution is that all mechanical parts have to essay, be isolated. Cognitive-behavioral For An Indian Adolescent. Moreover the risk of discharges caused by the conducting plasma is arthur essay high .
The number of articles re- porting this alternative arrangement is low   . With both this settlement is possible to do High Resolution Mass Spectrometry (HR-MS). The present work is focused on the mass spectrometry rst step: the analyte ionization through an indian with a clinical study, ICP; therefore the following argumentation will be focused on the plasma source.9 2.3 ICP-MS applications. In order to complete the ICP-MS introduction, an overview on the possible applications is provided in the following. Referring to the examples chosen by Jakubowski et al.  in the sector eld devices area, it is possible to group the applications in three categories: їЅ' multi-element analysis, їЅ' isotope ratio applications, 9Nowadays, ICP sources have a similar design in all commercially available instru- ments, independently on the type of mass separator .
9 Figure 2.6: Schematic of an ICP-MS system. Various gaseous (dashed lines) and liquid (solid lines) sample introduction devices are shown . їЅ' speciation analysis. Multi-element analysis has been the devany major application area of sector eld (SF) instruments during the tungkol last 15 years. The main reasons for devany, their success are the capability of multi-element measurements, high sensitivity, low detection limits and fast and cognitive-behavioral therapy for an indian adolescent depression, accurate direct data acquisition of the majority of nuclides suering from arthur devany, spectral interferences at low mass res- olution. ICP-SFMS is used for biological and tungkol sa kalikasan, environmental analyses: to devany essay, determine element concentrations in body uids - such as blood, urine and cerebrospinal uid -, for the detection of trace elements in sections of hu- man hairs, for monitoring Ca in biological samples - to study Ca pathways and metabolism -, in water research, to monitor the persuasive tools fate of heavy metals (including Rare Earth Elements) in the environment, for arthur devany, the direct multi- elemental determination of trace elements in diluted sea water and for soil samples analysis - in order to monitor heavy metal mobilization. In in- dustrial applications and materials research, ICP-MS is mainly used in the semi-conductor industry and in the characterization of cognitive-behavioral for an adolescent depression study pure and arthur, ultra-pure materials; other applications are quality control of ultra-pure water, am- monia and acids, determination of the stoichiometry and trace impurities in thin barium strontium titanate perovskite layers (used in microelectron- ics), assessment of the purity of TlBr single crystals and creative writing essays, forensic studies or provenance determination. Laser Ablation coupled to essay, ICP-SFMS has to be mentioned because it is used either for bulk quantication of elements, for depth proling or the identication of contamination spots. Concluding, multi-element analysis is used in food and nutrition science - for film analysis, beverages, 10 vegetables, sh and infant food - and in essay geological and radionuclide appli- cations - for library thesis, studying trace element concentrations in geological samples, soils, sea water or sea water particulates10 and radionuclide determination. The superior sensitivity and arthur devany essay, the capability to avoid spectral interferences by cognitive-behavioral indian depression case, operating at high mass resolution are undeniable advantages for isotopic analysis as well. Applications range in many elds: from biological to en- vironmental samples, from geological to provenance and migration studies.
Tracer experiments were conducted to investigate elemental uxes in, e.g., the environment or metabolic processes; natural variations in the isotopic composition of selected elements are used for solving problems in essay a biological context; Pb composition analyses are used to distinguish between natural, geogenic Pb and anthropogenic Pb; through Sr isotopic analysis11 is film analysis pos- sible to trace the provenance of goods, agricultural products, food or even animals and humans - in archaeometry and forensics. Even radionuclide applications are important: ICP-SFMS measurements have proven useful in the nuclear industry and in the related environmental and safety aspects. Irradiated nuclear fuel has been analyzed by means of MC-ICP-MS for devany, the optimization of the fuel cycle and for safeguard aspects. At last, ICP-MS instruments are used in analytical problems related to biological systems or environment studies; information on speciation is essays required in order to understand processes related to toxicity, transport and bio-availability of metals or biological processes in which metals are involved. Arthur Essay. In life science and environmental applications high mass resolution is needed for proteins studies (e.g. for the characterization of metal containing or metal-binding proteins in biological systems), analysis and epiphany essays, quantication (e.g. for selenoproteins, metalloproteins and protein-bound metals). 10Sea water temperatures can be calculated from Mg/Ca ratios.
11Isotopic and elemental signatures bear the potential of providing unique ngerprints which can be directly related to the origin of the sample investigated. 11 Chapter 3 Plasma torch The ICP is arthur devany generated in a discharge gas (Argon, in our case) without using any electrode, by the application of a high frequency electrical current to an induction coil, enveloping the plasma torch , as it will be explained in university library the following. Arthur Essay. The development of ICP sources began in 1942 , when Babat published his rst paper on the properties of electrodeless discharges and realized the rst ICP operating at essay writing tungkol atmospheric pressure. About 20 years later, Reed published two articles on his ingenious approach to the stabilization and devany essay, thermal isolation of the producted plasmas. He under- lined three properties that make ICP a superior source of atomization and cognitive-behavioral indian adolescent with a clinical, ionization: high gas temperatures, capability of being sustained in noble gas environments and freedom from electrodes (representing a contamina- tion). As a result of these good analytical performances, studies on ICP were started in 1962 and the rst use of an Inductively Coupled Argon Plasma as an ion source for mass spectrometry dates from 1978 . Sciex, Inc., introduced the essay rst commercial instrument for ICP-MS at the 1983 Pittsburgh Conference, which catalyzed an explosive growth of interest in the technique . Essays Gcse. In fact, until that year, commonly used ion sources were not suitable for essay, the rapid, direct examination of aqueous samples because extensive sample preparation was required.1 Then, several other instrument companies conducted ICP-MS research and, between 1985 and writing sa kalikasan, 2010, about arthur devany essay 20 commercially available instruments were introduced to the market (con- sidering both the persuasive essay ICP and essay, the GD plasma source) . For a complete list of the commercial sector eld mass spectrometers with plasma based ion sources see Table 3.1.
To understand how an ICP works, it has to be known that high frequency currents owing in an induction coil generate an oscillating magnetic eld, whose lines of force are axially oriented inside the coil. In an ICP, the persuasive tools plasma torch - where plasma is generated - is enveloped in 2 or 3 turns of essay copper tube, cooled with either water or Argon; this settlement produces an electromagnetic inducted eld by a time-varying magnetic eld. Epiphany Essays. The power 1The sample was evaporated onto a lament for thermal ionization or incorporated into arthur devany essay, an electrode for persuasive essay tools, spark ionization before the sample-containing substrate was physi- cally mounted in arthur essay the vacuum system. The associated time requirement for these opera- tions was rendering the routine analysis of large numbers of solutions impractical. 12 Table 3.1: Commercial sector eld mass sp ectrometer with plasm a based ion source s 1985-2010  Name Man ufacturer a Y ear of writing Status T yp e of instrumen t Geometry in tro duction V G 9000 V G Elemen tal 1985 discon tin ued GD-SFMS rev erse Nier-Johnson Plasmatrace I V G Elemen tal 1988 discon tin ued ICP-SFMS Nier-Johnson JMS-Plasmax I JEOL 1991 discon tin ued ICP-SFMS rev erse Nier-Johnson Plasma 54 V G Elemen tal 1992 discon tin ued MC-ICP-SFMS Nier-Johnson Elemen t Finnigan MA T 1993 discon tin ued ICP-SFMS rev erse Nier-Johnson Plasmatrace II V G Elemen tal 1994 discon tin ued ICP-SFMS rev erse Nier-Johnson JMS-Plasmax 2 JEOL 1995 discon tin ued ICP-SFMS rev erse Nier-Johnson Nu Plasma Nu Instrumen ts 1997 discon tin ued MC-ICP-SFMS Nier-Johnson Axiom V G Elemen tal 1998 discon tin ued ICP-SFMS Nier-Johnson Axiom MC V G Elemen tal 1998 discon tin ued MC-ICP-SFMS Nier-Johnson Elemen t 2 Thermo Quest 1998 av ail able ICP-SFMS rev erse Nier-Johnson Nu Plasma 1700 Nu Instrumen ts 1999 av ail able MC-ICP-SFMS Nier-Johnson Neptune Thermo Quest 2000 av ail able MC-ICP-SFMS Nier-Johnson IsoProb e-P GV Instrumen ts 2004 discon tin ued MC-ICP-SFMS magnetic se ctor + hexap ole collision ce ll Elemen t XR Thermo Electron 2004 av ail able ICP-SFMS rev erse Nier-Johnson A ttoM Nu Instrumen ts 2004 av ail able ICP-SFMS Nier-Johnson Elemen t GD Thermo Electron 2005 av ail able GD-SFMS rev erse Nier-Johnson SPECTR O MS Sp ectro Analytical Instrumen ts 2010 av ail able MC-ICP-SFMS Mattauc h-Herzog Nu Plasma II Nu Instrumen ts 2010 av ail able MC-ICP-SFMS Nier-Johnson Astrum Nu Instrumen ts 2010 av ail able GD-SFMS Nier-Johnson Neptune plus Thermo Scien tic 2009 av ail able MC-ICP-SFMS Nier-Johnson a Man ufacturer names are according to arthur devany essay, their names when the instrumen t w as in tro duced. Cognitive-behavioral Therapy Indian Adolescent Depression Case. 13 supply is given by a radio-frequency (rf) generator, that ranges typically between 1 and 1.5 kW, at a frequency of about 27 MHz. A sketch of the plasma torch used by Neptune MC-ICP-MS is arthur represented in Figure 3.1; it is essay tungkol sa kalikasan usually referred to essay, as a Fassel torch, from the american chemist Velmer A. Fassel. The following treatise, which aims to give an overall description of the torch, is mainly based on the publications by Fassel  and personal epiphany essays, Houk , while a detailed nomeclature description of the system can be found elsewhere . To form a stable plasma, a pattern of three Argon ows is needed; so the Fassel torch consists of three concentric quartz or fused silicate glass tubes, carriyng a total Argon ow between 11 and 18 L/min. Since the plasma temperature is so high, a thermal insulation is needed; the outer tube main operation is thus to insulate the devany device from the outside environment. To this aim, the Reed's vortex stabilization technique is used : a ow of Argon tangentially introduced streams upward, cooling the inside walls of the epiphany outermost quartz tube and arthur, centering the plasma radially in personal the tube.
The outer tube has a 2.5 cm diameter and arthur devany essay, carries a plasma ow between. 10 and therapy adolescent depression, 15 L/min; it is also responsible for the main supply of Ar to the plasma. The middle tube provides the auxiliary gas (0.5 їЅ'' 2 L/min), whose role is to lift the plasma o the injector. Arthur Essay. The auxiliary gas is injected tangentially too, in order to epiphany, create a vortex and stabilise the plasma. The eect of the previous two tubes is to generate a stable toroidal plasma through the centre tube, in arthur which the sample aerosol is injected. The Argon ionization is started by a spark produced by a Tesla coil; the tungkol sa kalikasan ions and electrons this way formed interact with the oating magnetic eld given by the load coil. Arthur Devany. The result is a high frequency oscillating electron and ion current, which heats the plasma gas to university library thesis, high temperatures: gas-kinetic temperature of 5000 їЅ'' 8000 K, ionization temperature of about 7500 K, excitation temperature of 6500їЅ''7000 K, and electron temperature of about.
10000 K; then plasma is maintained by arthur, inductive heating. Library Thesis. The aerosol generated from the sample is either created by nebulization of a liquid sample solution or consists of solid particles carried by devany, a gas ow when sample material is ablated by a laser; it is then transferred into the centre of the creative gcse plasma by an Argon gas ow (0.8 їЅ'' 1 L/min), through the inner tube. To be eectively atomized and arthur devany essay, excited, the sample aerosols should remain localized in the interior high-temperature environment of the plasma as long as possible. The sample species employ about 2 ms to reach the observation height of 15 to 20 mm above the load coil (ALC); this time is sucient in an environment with such a temperature (between 5000 K and 8000 K) to give rise to an ecient volatilization and atomization of the film analysis sample components and subsequent excitation and arthur essay, ionization of the tools atoms thus formed .2 The Saha-Eggert equation  can be used to devany essay, estimate the eciency of 2Just for a comparison, the residence times and temperatures experienced by creative writing gcse, the sample are approximately twice those found in the hottest combustion ames common used in AAS . Devany Essay. 14 Figure 3.1: Inductively Coupled Plasma conguration . 15 the ionization for the resulting analyte atoms, using the electron densities and temperatures typical for the ICP discharge: it results that all elements with rst ionization potentials below 8 eV are completely ( 90%) ionized and even elements with rst ionization potentials between 8 and 12 eV are ionized by more than 10% . Persuasive Tools. So the plasma source ionization eciency is arthur devany much higher for the ICP than for the other devices;3 moreover, referring to creative writing gcse, atomic spectroscopy, it is arthur essay also economically convenient.4 Predominantly singly charged ions are generated for all elements of the periodic table. Thus, the cognitive-behavioral indian depression a clinical study mass spectrum observed mainly consists of devany essay signals corresponding to the singly charged elemental ions of the nuclides of all elements present in the sample. ICP sources had been developed for optical spectroscopy; when they were adapted for mass spectrometry, secondary discharges (called pinches or pinch eects) between the plasma and the sampler arose. They were caused by thesis, the rf potential in the plasma and they gave rise to numerous deleterious eects: rapid deterioration of the arthur devany essay sampling and the skimming cones, contamination of the plasma with sampler and skimmer material, high photon noise and high ion energies with large energy spreads . In order to decrease this phenomenon, the Neptune torch is equipped with a guard electrode (GE), also called torch shield or capacity decoupling.
This is a grounded platinum foil placed in between the therapy adolescent depression a clinical plasma torch and the load coil. Since one end of the coil is connected to the rf source and the other end is grounded, a potential gradient exists along the coil, which becomes capacitively coupled into the plasma. The plasma, in turn, is electrically coupled through the arthur essay sheath (see chapter 4) to essay sa kalikasan, the sampler. These two impedance sources act as a potential divider; if plasma potential is arthur essay too high a strong secondary discharge forms between the plasma and the sampling orice . Gray showed  that insertion of a grounded, slotted metal cylinder (the torch shield shown in Figure 3.2) between the load coil and the outer wall of the torch shields the d.c. potential component from the plasma and provides a low plasma potential - in the following it will be shown that this last gain improves the operation of the ICP-MS. In addition, the therapy adolescent depression case study guard electrode decreases the ion energy spread, and thus can help to increase the arthur devany essay overall ion transmission . In order to minimize the library plasma potential and secondary discharge, mainly two other dierent load coil congurations have been used:5 їЅ' inverted (or reversed) load coil: the load coil is grounded at the down- stream end nearest the devany sampler; їЅ' center-tapped load coil: a high voltage of epiphany equal amplitude but opposite arthur devany phase is applied to the coil edges, while the center is connected to ground. 3In the Thermal Ionization Mass Spectrometry is lower than 5%. 4The operating cost of these plasmas owing in the Fassel torch, exclusive of the electrical power, is lower than the cost of the therapy for an adolescent with a clinical case study gases needed to operate the nitrous oxide- acetylene ame commonly used in Atomic Absorption Spectroscpy (AAS).
5Also the arthur essay interleaved and the balanced load coils have been studied . 16 Figure 3.2: Sketch of tools a plasma torch in which is clearly visible the arthur essay guard electrode. Library Thesis. Figure 3.3: Design features of an inverted load-coil (A) and devany essay, a center-tapped coil (B) . 17 Chapter 4 Extraction interface In coupling an Inductively Coupled Plasma and a Mass Spectrometer, the trouble is film analysis that ICP operates at atmospheric pressure, whereas MS requires an arthur, ultra high vacuum (UHV) condition (operating pressure less then 10їЅ''7 Pa), otherwise the ions would be scattered by the gas atoms. The solution to tungkol, such a pressure discrepancy is to interpose three interfaces between the gas source and the analyzer, resulting in a four-regions solution. While the rst one is at arthur devany essay ambient pressure (105 Pa), the second region (called interface) is pumped by a regular rotary pump, to obtain a pressure of 2 · 102 Pa.
The higher is the grade of vacuum, the better are the instrumental performances features, such as transmission eciency or abundance sensitivity; as a con- sequence, stronger vacuum pumps are becoming popular. To preserve the high vacuum condition in tools the third region, a slide valve is interposed; it is only opened when the plasma is operating stable and is closed before plasma shutdown, to arthur, isolate the high vacuum. Persuasive Essay. The third region, where lenses are located, has a pressure of about 5 · 10їЅ''2 Pa, while the arthur devany essay mass spectrometer (nal region) operates in ultra high vacuum conditions (about 10їЅ''7 Pa). It has been found that such a low pressure is advantageous in the case of multi collector devices ; in order to provide this result, the analyzer is separated from the film analysis lens system by a second valve and additional ion getter pumps are required. The development and improvement of the ion sampling interface for ICP-MS have been crucial aspects of the success of the technique. The rst analytical mass spectrometer for ion sampling from an arthur, ICP used a stagnant layer type sampling interface  1. Writing. At the end of the arthur plasma torch, an interface was present to extract a small fraction of plasma with its ions into a vacuum system.
This interface was composed by two cones, a sampler and a skimmer. The rst one consisted of a water-cooled copper cone, on film analysis, whose tip was mounted a molybdenum disk, through whose center was drilled a 50 µm diameter orice. Due to this small diameter, an aero- dynamically stagnant layer of arthur essay gas formed between the two cones, as shown in Figure 4.1. 1This type of pinhole sampler was adopted in the early days from ame and plasma sampling methodology and essay writing tungkol, from the devany essay original work of Gray with a d.c. capillary arc plasma . 18 Figure 4.1: Diagram of boundary layer sampling interface for ICP-MS . Since electrons are faster than ions, a space-charge sheath containing an excess of ions builded up around the essays tip of the devany cone. This stagnant bound- ary layer was in thermal contact with the relatively cool sampler, making the layer temperature intermediate between the creative essays gcse plasma one and the sam- pler one. As the boundary layer was extended across the sampler tip, ions were extracted only after a large number (about 106) of collisions with the layer. This transport through the boundary layer induced several liabilities: rst of all it was probably facilitating ion-electron recombination, ion neu- tralization at the sampler walls, charge exchange, ion-neutral attachment, nucleation and condensation of solid deposits (mainly due to the formation of involatile metal compounds) and some occurring reactions might have been catalyzed by the metal surface of the orice disk. Secondly, consid- ering the supersonic jet downstream the sampler cone, collisions leading to clustering, ion-electron recombination or charge exchange also occurred. Devany Essay. Consequently, sample deposition occurred in the sampling orice - metal oxide and metal hydroxide ions had been observed.
Progressive solid con- densation of sample material both made the extraction eciency of analyte ions gradual decreasing and restricted the useful life of orices. Even nowa- days the rst components that have to be changed in a mass spectrometer are the sampler and the skimmer cones: their lifetime is limited by the sputtering in the region immediately behind the aperture . Back to the problem of solid deposition, with this conguration biological uids required a dilution factor of several hundred before analyses of such solutions could be performed for personal essays, more than one hour. The consequent deterioration in powers of detection for analyte elements was not acceptable for various ap- plications. Devany. Owing to cognitive-behavioral therapy for an indian adolescent with depression a clinical, the diculties arised with this type of sampling, a new 19 sampling interface has been adopted: the supersonic nozzle and skimmer .2 The version of devany this technique used in our ICP-MS consists of a large sampling orice: with this conguration it is possible to break through the intermediate sheath and to essay, have a continuum gas ow condition. The sheath is a thin ply around the inner edge of the sampling orice; in this ply the charged particles shield the rest of the gas ow from the potential on the sampler (usually grounded). Arthur. Therefore the extracted ow passes through the sampler as a quasineutral plasma,3 i.e. with essentially equal densities of ions and electrons.4 Cool layers are still present, but they form obliquely around the inside edge of the film analysis orice, instead of across its mouth . Consequently the salt deposition and the oxide ion formation are much less severe . So, this conguration provides several advantages: їЅ' a much higher total ow of ions; їЅ' a more representative sample of arthur devany essay ions from the essay plasma; їЅ' greater resistance to plugging from deposited solids.
The improved resistance to erosion and expansion is arthur devany also because such an orice is made with relatively thick metal near the tip. Thesis. Figure 4.2 is a scale drawing of continuum sampling interface. The sampler (or nozzle) (A) is a nickel-made cone, in which tip is drilled a 0.8 mm diameter orice with a length of 0.25 mm. The internal and arthur, external sampler angles are 90їЅ'їЅ and 120їЅ'їЅ, respectively. Coaxially placed, 7 mm downstream the sampler, there is the skimmer, made from stainless steel with 50їЅ'їЅ and cognitive-behavioral for an indian adolescent depression a clinical case study, 60їЅ'їЅ internal and devany essay, external angles, respectively.5 The short distance between the two cones allows a sequential pressure decrease and it could be varied by changing the thickness of the Teon spacer (C). Both the sampler and essay, skimmer are grounded; nevertheless there could be some benets applying a voltage to the skimmer - see section 7. From the work by Hu et al.  it results that larger sampling orices could bring higher ion signals: the devany plot in Figure 4.3 shows how the library Co and Bi ion count rate increased drilling out the circular aperture progres- sively. Since also the background pressure increased after each drilling, it was necessary to empirically adjust the separation between the sampler and the skimmer to maximize the ion signal. Moreover, a small orice is more subjected to arthur essay, clogging compared to a bigger one: as it can be seen in Figure 4.4 a pressure decreasing in the case of the personal epiphany essays smaller orice is observed, since it plugs quickly. In conclusion, enlarging the orice could provide a double 2This type of sampling interface have been in use since the pioneering work of Kantrowitz and Grey in 1951 . 3The charge density is considered to devany, be suciently high as to ensure that the university thesis charac- teristic Debye length is small with respect to devany, the dimensions of the interface components - under this condition it's possible to consider the writing essays gcse beam as neutral.
4This concept is supported by calculations based on a paper by Axford and Hayhurst. Arthur Essay. 5Nowadays, dierent skimmer cone designs are available, characterized by dierent transmission eciency . Essay Writing Tungkol Sa Kalikasan. 20 Figure 4.2: Scale drawing of continuum sampling interface for ICP-MS . 21 Figure 4.3: Ion count rates as a function of sampler orice diameter . benet: a higher ion signal and an improved tolerance to orice plugging. However it has to be underlined that these studies were conducted with a continuous ow ultrasonic nebulizer, which transported material to the plasma at a rate at least 10 times greater than the one obtained with a con- ventional pneumatic nebulizer. As a consequence, the second improvement would not be relevant in our case. In order to understand the arthur devany performance of this interface and particu- larly to nd the parameters needed in the simulations (see section 6.4) the adolescent with a clinical gas ow (in molecules/s) through the sampler can be calculated through equation (4.1)  used by Olivares and Houk in their article (dating 1985): U0 = їЅ'f (і)NAD 2 0 P0 4 їЅ'' mRT0 (4.1) where f(і) = їЅ'' і · [2/(і + 1)](і+1)/2(іїЅ''1) , NA is Avogadro's number, D0 the orice diameter, P0 the devany essay ICP pressure, m the mean molecular weight of persuasive tools Argon, R the gas constant, T0 the source gas temperature of the ICP, and arthur devany, і is the specic heat ratio at constant pressure and volume (Cp/Cv) of Argon. 22 Figure 4.4: Normalized interface pressure as a function of time for continu- ous nebulization of tungkol 1000 ppm Y at sampling orice . 23 The ow through the skimmer cone is given by the following equation: US = U0 · f (і) DS XS 2 (4.2) where DS is the devany essay skimmer diameter and XS the skimmer-to-sampler distance. These theoretical results are in good agreement with the experimentally obtained values for an ICP with 10 mg/l Co solution .
In a 1988 article, Douglas and tools, French provided another way to describe the gas expansion through these two orices; in arthur essay their article the gas ow across the sampler was given by essay,  G0 = 0.445 n0 a0 D 2 0 (4.3) where n0 is the source number density and arthur, a0 the speed of sound in the source: a0 = і k T0 m (4.4) (k is the writing essays gcse Boltzmann's constant). The equation for the gas ow through the skimmer uses the gas density and the ow velocity at the skimmer tip, n(xS) and v(xS) respectively, and the area of the essay skimmer orice AS:6 GS = n(xS) v(xS) AS (4.5) These two models (the one by Olivares and Houk and the one by cognitive-behavioral for an indian adolescent with a clinical, Douglas and French) are based on a common assumption: as the plasma plume is expanding from a sonic orice into arthur devany, a region of lower pressure, it produces the development of the free jet shock wave system . Library Thesis. As it can be seen in the cross sectional view showed in Figure 4.5, the ow eld consists of a dark core portion, named zone of silence (unaected by the pressure changes along the jet boundary), laterally bounded from a barrel shock and arthur essay, ending with the so called Mach disk (its thickness has been found to be of the order of magnitude of the mean free path ). This phenomenon has been well characterised by Ashkenas and personal, Sherman ; they calculated the distance downstream the sampler at which the Mach disk forms: xM = 0.67D0 · p P0/P1 (4.6) where P1 is the interface background pressure. This relationship has been conrmed experimentally by optical measurements of emission excited in arthur devany the Mach disk . As the gas passes through the sampler, it expands adiabatically into the low pressure region; since the for an indian adolescent a clinical study mean free path (») is much smaller than the diameter orice, several collisions between fast atoms from the dark core and background atoms occur. Essay. This phenomenon causes the essay tungkol formation of the Mach disk and the barrel shock, depicted in Figure 4.5. Moreover, through 6The ow velocity is nearly constant at p5kT 0/2m . 24 Figure 4.5: Cross sectional view of supersonic expansion behind the sampler . this scattering process, the random thermal motion of atoms in the plasma is arthur converted into directed motion in the zone of silence: the ow velocity can than exceed the university library local speed of sound and the Mach number becomes greater than one (M 1).7 The Mach disk formation is observable analyzing atom velocities and temperatures (showed in Figures 4.6 and 4.7) as a function of distance downstream the sampler cone. The rapid acceleration and cooling of the atoms are expected from a supersonic expansion  and is represented by the series of devany essay point that start about therapy indian adolescent 2 mm downstream the sampler. At a position of about 10 mm another population of atoms forms: this new population, slow and hot, is given by fast atoms which collide with background atoms and constitutes the Mach disk.
In order to nd a numerical result for the gas ow through both the sampler and the skimmer using the two models previously shown, some other relations are needed. The Mach number in the plasma is less than one (M 1); as the gas passes through the sampler the density decreases, the ow speed increases and M increases too. In this region the centerline Mach number for a monoatomic gas - as in devany essay this case - is given to a very good approximation by M = 3.26(x/D0) 2/3 їЅ'' 0.61(x/D 0) їЅ''2/3 (4.7) where x is the axial distance behind the orice. This means the creative essays gcse Mach number reaches 1 at arthur devany a distance equal to 0.5 orice diameters downstream 7The Mach number is dened as the ratio between between the gas ow speed (u) and the local speed of sound (a0). 25 Figure 4.6: Axial velocity dependence downstream from the sampler cone: 4 fast, cold component, slow, hot component . Figure 4.7: Axial temperature dependence downstream from the essays sampler cone: 4 fast, cold component, slow, hot component . 26 Figure 4.8: Scatter plot of the gas temperature as a function of the distance from the sampler in the free jet, obtained from essay, equation (4.9). the adolescent depression a clinical case sampler. Furthermore the gas density and temperature decrease inside the jet, according to the following equations: n0 n = 1 + M 2 і їЅ'' 1 2 1/(іїЅ''1) (4.8) T0 T = 1 + M 2 і їЅ'' 1 2 (4.9) where n0 and T0 are the gas density and temperature in the source.
Equation (4.8) could be approximated back to the onset of the Mach disk by n(x) = 0.161 n0 (D0/x) 2 (4.10) This relation, that describes the drop in intensity of neutral species along the centerline, has been experimentally conrmed by Niu and Houk, when in 1994 they measured electron densities in the interface with a Langmuir probe . The plot in Figure 4.8 represents the temperature drop described by arthur devany, equation (4.9); this decrease corresponds to a narrowing of the essay width of the velocity distribution (Figure 4.9) as the random thermal motion is arthur converted into university thesis, directed motion with a relatively uniform speed. A combination of all the displayed equations have been used to obtained the results highlighted in Table 4.1. The gas ows have been obtained with two dierent equations and are in good agreement, especially in devany essay correspondence of the sampler cone. Cognitive-behavioral For An Adolescent Depression A Clinical Case Study. In 27 Table. 4.1: Parameters and. constan ts used to calculate the. o w - highligh ted.
skimmer with tw o dieren t mo. Houk  Douglas and. h  і 1 .67 sp ecic heat ratio C p /C v і 1 .67 sp ecic heat ratio C p /C v f (і ) 0 .726661 T 0 5000 K gas. temp eratur e D sa 0 .8. mm sampler diamete r m 6 .6 · 10 23 g relativ e atomic mass P 0 10 5 Pa ICP pressure D sa 0 .8. mm sampler diameter M 39. g/mol relativ e molecular w eigh. t a 0 1317 .97 m/s sp eed. of sound in the. source T 0 5000 K gas. temp erature n 0 1 .5 · 10 18 cm їЅ'' 3 source densit y x 7. mm sampler to skimmer distance U 0 5 .4 · 10 20 atoms/s gas.
o w through the. sampler G 0 5 .6 · 10 20 atoms/s gas. o w through the. sampler D sk 0 .8. mm skimmer diame ter M sk 14 Mac. mm sampler to skimmer distance n sk 3 .0 · 10 15 cm їЅ'' 3 gas. densit y at the. skimmer P i 861 Pa impact pressure at the. skimmer v 1 .6 · 10 5 cm/s o w velo cit y D sk 0 .8. mm skimmer diameter U S 5 .1 · 10 18 atoms/s gas.
o w through the. skimmer G S 2 .5 · 10 18 atoms/s gas. o w through the. skimmer 28 Figure 4.9: Wide velocity distribution in the plasma compared to the nar- rower distribution in the supersonic jet . the region close to arthur devany, the skimmer there is a factor 2 between the two models results; this dierence is negligible since the gas ow probably depends on many other contributions - e.g. the analyte species, the nebulizer gas ow - that can signicantly aect the nal result. Regarding the essay sampler to skimmer distance, Douglas and French showed that the best arrangement corresponds to having the skimmer tip about. 2/3 of the arthur devany way back to writing essays gcse, the onset of the Mach disk  . This result approximately agrees with the one obtained for the maximum intensity in the case of a neutral beam from Campargue expansion : XS = 0.125 D0 D0P0 »P1 1/3 (4.11) Even if here » is referred to as the mean free path inside the sampler orice, it has no particular subscript as it is expected to be nearly equal to arthur essay, the one for the gas outside the sampler in the ICP.
The skimmer protrudes into the zone of silence so that shock waves form behind the skimmer tip o the outside walls of the skimmer, as shown in the sketch in Figure 4.10. With this conguration, the metal wall of the epiphany skimmer where the second shock wave begins is thick enough to conduct away the heat generated and devany, the thin edge of persuasive tools metal at the skimmer tip remains stable. Otherwise, if the devany essay skimmer was located after the Mach disk, the sampled gas would be reheated by collisions with background gas in essay the Mach disk; this process would lead to the formation of a spherical white emitting region. The heat this way producted would be directly transferred to the skimmer tip, too thin to essay, properly conduct the heat away; the result would be the melting or the rapid degradation of the skimmer tip . Calculation of the university thesis Knudsen number Kn, especially at the skimmer, is also instructive; it is dened as the ratio of the mean free path » to the 29 Figure 4.10: Eect of dierent sampler-skimmer distances. (a) Skimmer at normal position used for analysis. (b) Skimmer outside the zone of arthur essay silence .
30 skimmer diameter DS: Kn = » DS (4.12) In the small scale Kn quanties the failure of the Navier-Stokes description: in fact this model corresponds to the collision-dominated transport limit of small Knudsen number Kn 1. More specically, in the presence of hy- drodynamic gradients in a homogeneous gas over lenghtscales characterized by Kn 1, the Chapman-Enskog expansion procedure can be applied to the governing kinetic (Boltzmann) equation to show that the gas response can be described by therapy adolescent with a clinical case, linear-gradient constitutive relations which lead to the Navier-Stokes description . Practically, the essay lower the Kn, the smaller the number of collisions is; Kn would have to film analysis, be much less than unity (i.e. » DS ) for the beam to expand through the skimmer without collisions. The mean free path » can be expressed through the following relation, based on viscosity measurements and kinetic theory arguments : » = 16/5 µ nm q 2їЅ'kT m = 16/5 µ n їЅ'' 2їЅ'kT m (4.13) where n is the molecular number density, m the particle mass and k the Boltzmann's constant. It is possible to refer to arthur essay, the viscosity coecient both with µ and ·. Niu and Houk report another relation for the Knudsen number: Kn = » DS = 1 1.414їЅ'їЅ'nDS (4.14) where їЅ' is the gas kinetic cross section for Ar (4.1 · 10їЅ''15 cm2). The result obtained applying these two relations with the settings previously described are Kn = 0.3 and » = 0.2. These values are consistent with several articles    . The literature concerning supersonic expansions indicates that in personal epiphany essays this case two main disturbances are to be expected around the tip : a thin shock in arthur devany front of the skimmer and perturbation of the straight line beam ow by collisions of the beam with atoms reected from the skimmer wall. Considering now the gas ow rate calculated for our particular case, the- oretically the writing total ion current at the base of the skimmer should be about.
0.4 mA; this result is consistent with several papers: for example, Gillson et al. , even if with a slightly dierent setting, calculated an ion current of. 1016 ions/second, corresponding to 1.5 mA. This current has been calculated considering that through the arthur devany skimmer passes only 2.6% of the central ow of the ICP. Considering the theoretical loss of analyte ions for Y, Chen and Houk calculated a transmission eciency from the skimmer to the detector is 0.02%. As a consequence, the overall eciency of an ICP-MS is about. 5·10їЅ''6 ; in other words, theoretically, for library, every 106 analyte ions in the central channel of the devany essay ICP, only ve ions reach the detector. As it will be explained later, this number is even lower in the reality. Personal. Through a comparison with a three-aperture ICP-MS interface, they deduced that many ions are lost between the skimmer tip and the ion optics or inside the ion optics itself. So 31 it is crucial to understand what happens in this region and how ions are lost. Chapter 6 is aimed to arthur, simulate the region where particles y, including the skimmer and the rst lens (named extraction lens), in order to study and characterize the formed beam.
Resuming the work by Gillson et al., they repeated the ion current measurements8 with the same settings for library thesis, a heavier ion (U+); the arthur ux resulted higher. This phenomenon is called instrumental mass discrimination and has been deeply investigated (e.g., by library, Kivel et al. ), since it hampers accurate determination of absolute isotope ratios. In general, it consists in having at arthur devany essay the spectrometer a stoichiometric composi- tion dierent from the one characterizing the original sample material. It has been reported that, typically, analyzing two isotopes, the for an indian adolescent case study heavier has a higher transport eciency: the dierence is essay about 10 їЅ'' 20% in library thesis the case of arthur essay light elements and down to film analysis, 1% for heavy elements. Four main factors are at essay the base of mass discrimination: їЅ' sample introduction and ion generation; їЅ' collisions; їЅ' space charge eect; їЅ' energy-selective ion transmission. Persuasive Tools. The rst and the last one are not studied in the present work, since it is limited to arthur essay, the region dened by the skimmer and film analysis, the rst ion lens. As the arthur devany essay plasma is quasi-neutral until the starting of the skimmer, it's reason- able to assume that mass discrimination in the interface is mainly caused by essay writing tungkol sa kalikasan, collisions.
This hypothesis is arthur consistent with the cognitive-behavioral for an indian adolescent with a clinical work by essay, Taylor and Farnsworth : they found the absence of any space charge eect dur- ing the epiphany essays ion transfer from the source to the spectrometer. Moreover, for the present work, collisions have been considered a negligible contribution compared to space charge eect. As a consequence, mass discrimination upstream the skimmer has not been considered; the devany essay following investigation is limited to the region downstream the skimmer cone, up to personal epiphany essays, the extraction lens.9 Resuming mass discrimination due to space charge eects, it can be explained by postulating that the ion beam within the skimmer is devany space charge limited: its density is so high that mutual repulsion will not allow the persuasive essay tools ions to remain tightly focused. Since all ions have the same charge, they are subjected to the same force: as a consequence, lighter ions are de- focused (and then colliding on the skimmer walls) much more readily than heavier ones. More than upstream, the space charge is considerable in the region downstream the skimmer. In fact, according to the model by Douglas and French , plasma is arthur devany sampled without signicant charge separation.10 8They used a stainless steel collector - situated 1 in. from the film analysis base at the skimmer - consisting of arthur essay three concentric rings and a central circular stop.
9Study of mass discrimination after charge separation can be found elsewhere . 10In an creative, alternate model, presented by devany essay, Chambers et al., it is assumed that signicant charge separation occurs between the film analysis sampler and arthur essay, the skimmer; therefore the ion current through the skimmer would be signicantly less than that estimated in this work. 32 Behind the skimmer, where the beam expands, there are three main con- tributions to the loss of the writing tungkol sa kalikasan ions: the density decreasing - proportionally to 1/x2 (where x is the distance from the skimmer) - as a consequence of the expansion, the arthur devany essay beam spreading and the preferential loss of electrons. Personal Essays. This last phenomenon could be explained considering the Debye length »D; downstream of the arthur skimmer »D is signicant compared to the dimensions of the beam and electrons are lost readily to the inner wall of the skimmer because their high mobility. Moreover, in this stage, the electrostatic eld penetration from the extraction lens becomes signicant; as a consequence of these two eects, electrons leave a net axial positive space charge . Its signicance can be quantitatively described using the perveance P : P = I V 3/2 (4.15) where I is the total current and V the accelerating potential. P depends only on film analysis, the geometry of the arthur extractor and on the type of the particle . For a singly charged ion beam, space charge is negligible if P 10 їЅ''8 · (m ion/me) їЅ''1/2 (4.16) where mion and me are, respectively, the creative writing essays mass of the particle and of the electron. So, for Argon ions, the maximum perveance without signicant space charge eects is devany essay 3.7·10їЅ''11. Persuasive Essay. In the proximity of the skimmer P is equal to 1.9 · 10їЅ''7 , which exceeds the maximum perveance by more than a factor 5000. To obtain a rough estimate for essay, the maximum electron current (for argon), it is possible to assume the skimmer as a cylinder with diameter.
D and creative essays gcse, length L:11 Ie,max(A) = 38.6 · 10 їЅ''6V 3/2 D L 2 (4.17) The ion current is related to the electron one: Iion Ie = r me mion (4.18) therefore Iion,max(A) = 9.04 · 10 їЅ''7 r z mion V 3/2 D L 2 (4.19) As hinted before, another cause of losing ions is the rarefaction of the beam as it travels farther from the skimmer tip. Arthur Devany Essay. The Debye length in- creasing, by virtue of its inverse square root dependence on the ion density, causes also the ions (not only the therapy for an indian adolescent with depression a clinical case electrons) spreading. So, to enhance the transmission eciency, the distance between the skimmer tip and the ion optics has to be minimized. A substantial increase in arthur devany ion signal was 11The diameter at the base of the skimmer is library equal to arthur devany essay, its length; the average diameter of the skimmer is then about L/2 and the ratio D/L is about 0.5. 33 seen when this separation was reduced to 2.4 cm . At this position, the mouth of the rst lens was only 5 mm from the film analysis nearest surface of the skimmer wall. Closer separations were tried, but the voltage output for essay, the rst lens became unstable, because of an electrical discharge between the ion lens and the skimmer wall or due to a high current ow to the lens. In the Neptune MC-ICP-MS is the thickness of the separation valve limits the essay tools smaller distance between the skimmer and the lens.
Table 4.2: Resume of the torch and the extraction interface operating pa- rameters Forward power 1350 W Guard electrode Grounded Gas ows: Cool 14.6 L/min Auxiliary 0.9 L/min Sample 0.8 L/min Make-up 0.3 їЅ'' 0.5 L/min Injector Sapphire (narrow bore) Spray chamber APEX HF Cones:12 Sampler Aluminium 0.9 mm Skimmer Aluminium 1.0 mm 12Custom design by PSI. 34 Chapter 5 IBSimu To simulate what happens during the beam extraction from the plasma source, an ion optical computer simulation package have been used, IBSimu. This software is designed especially for the ion source community  and it is well suited for our particular aim because it is conceived for arthur devany essay, ion (both positive and negative) and electron plasma extraction. Its development started at LBNL in 2004 where it was used to design a slit-beam plasma extraction and nanosecond scale chopping for pulsed neutron generator. Later, at the University of epiphany Jyv¤skyl¤ (Finland), Department of Physics (JYFL), the code was made modular and suitable for many dierent types of problems. IBSimu has been documented and released with an arthur, open source license (it can be downloaded at: http://ibsimu.sourceforge.net/) and so it's well suited for use in the scientic community. It is epiphany used as a computer library through a C++ interface and it presents several peculiar advantages: їЅ' power and versatility; їЅ' customization and devany, inclusion of new modules; їЅ' automation and cognitive-behavioral therapy for an adolescent case, batch processing; їЅ' incorporation of code in other software; їЅ' easiness of use (on the main site there are two tutorials http:// ibsimu.sourceforge.net/tutorial.html and the reference manual http://ibsimu.sourceforge.net/manual_1_0_5new_solver/index. html); їЅ' possibility to do the diagnostics from code or with an interactive tool; їЅ' data exporting and visualization. The code is capable of solving electric elds in 1D, 2D (planar or cylin- drical symmetry) or full 3D simulation geometries and it can calculate rel- ativistic continuous wave or pulsed particle trajectories taking into account the space charge density. The starting point is the arthur essay denition of the ge- ometry, where the creative writing gcse simulation is arthur essay done, and the electrodes (including the 35 Figure 5.1: Operational diagram for solving the Poisson problem. grounded interfaces), using a mathematical description. Tungkol. In order to devany, calcu- late the electric potential, the essays simulation domain is divided in square meshes with constant step size, which dimension can be specied in the geometry section of the code. So the eld where particles y is devany discretized: for film analysis, each cell the Poisson's equation їЅ'' 2їЅ' = їЅ'' Ѓ 0 (5.1) is solved using nite dierence method (FDM) on arthur devany, the nodes of the mesh.
Then, the electrostatic potential is calculated through a solver, using an iterative approach (described in the following). The nite dierence representation for a vacuum node i is: їЅ'iїЅ''1 їЅ'' 2їЅ'i + їЅ'i+1 h2 = їЅ'' Ѓi. 0 (5.2) while Neumann (5.3) or Dirichlet (5.4) boundary conditions can be used for therapy indian adolescent with a clinical case, boundary nodes. їЅ''3їЅ'i + 4їЅ'i+1 їЅ'' їЅ'i+2 2h = dїЅ' dx (5.3) їЅ'i = їЅ'const (5.4) To achieve smooth electric elds on the solid edges, the edge nodes within the solids are adjusted to virtual potentials using subnode information about the geometry: ІїЅ'(x0 їЅ'' ±h) їЅ'' (± + І)їЅ'(x0) + ±їЅ'(x0 + Іh) 1. 2 (± + І)±Іh 2 = їЅ'' Ѓ(x0) 0 (5.5) On the edges of the simulation domain, every solver supports Dirich- let and Neumann (rst and second order approximations) boundary condi- tions. Arthur Devany Essay. The calculation can also include the generally accepted nonlinear plasma model for positive ion extraction; thermal background electrons of the epiphany essays plasma are modeled analytically in Poisson's equation (5.1) where. Ѓ = Ѓion їЅ'' Ѓe0 exp[(U їЅ'' Up)/(kTe/e)] and the plasma potential Up and arthur devany, the electron temperature Te are the model parameters. Ion charge density Ѓion is calculated from beam current density and film analysis, electron charge density Ѓe0 is devany essay set to Ѓion at plasma potential. The electric eld (needed for particle 36 trajectories) is obtained by numerical dierentiation and thesis, interpolation of potential, using nine closest neighboring mesh nodes.
Then, the code cal- culates the particles trajectory integrating the equations of motion, derived from Lorentz force, with adaptive Runge-Kutta Cash-Karp (fourth and fth order) algorithm. In 2D and with a null magnetic eld: dx dt = vx dy dt = vy dvx dt = ax = q m Ex dvy dt = ay = q m Ey This method has an automatic step-size adjustment for required trajec- tory accuracy. Arthur. The implementation of the essay writing tungkol sa kalikasan Runge-Kutta algorithm is used from the GNU Scientic Library. As the CPU available was multicore and the particle tracer is multithreaded, for a high eciency calculation eleven cores were used for ying particles and one for the potential determination. The particle tracer algorithm nds all the arthur devany meshes the trajectory passes through and deposits the personal charge of the arthur devany particle on the four (eight in university thesis 3D) surrounding mesh nodes.
The same procedure checks for collisions in arthur the mesh square. The code in Appendix A was the starting point in my work; to under- stand the extraction process and to optimize the fundamental parameters (Up and Te), I changed some parts of it, as it will be explained in the next chapter. Hereinafter there is a description of the main operations done by this rst code. After including all libraries needed (most of them have been written by Taneli Kalvas), some denitions are present: the number of iterations, the rst lens acceleration voltage V acc, the plasma potential. Up, the tungkol electron temperature of the arthur devany plasma Te, the film analysis number of arthur essay particles per species n_particles and sa kalikasan, the kinetic factor Ekin_factor (KF ). The last one is given by devany, the ratio between the kinetic energy KE and personal, the mass m; it is dened in this way in arthur order to be equal for all the particles, regardless of their mass (in fact they are sent with a given velocity, not energy). To have the kinetic factor in eV/amu it has been used the for an adolescent depression following equation: KF [ eV/amu] = 1.66 · 10їЅ''8 3.2 v 2 (5.6) where v is in m/s. Following the code, a rst array is dened to devany essay, list the masses of the simulated ions in addition to Argon and another one is for tools, the beam current (in µA). In the section Output denitions it is possible to set (through boolean variables) what to devany essay, print during the compiling and at writing the end of the 37 code: debug and verbose provide some status information, the GTK plot represents the trend of both the electric potential and space charge error and plotting produces several les (it will be explained in detail later). Before starting the geometry section, the function fname is dened; it is used in the plotting phase, to print the name of the dierent les produced in arthur devany essay it.
Then, in the geometry section, the skimmer, the interface and the ex- traction lens are dened, using a cylindrical simmetry: only the upper part is described and then, through a mirror function on x axis, the electric eld in the lower part is obtained. In this section the mesh dimension - really important in essay tungkol sa kalikasan the next chapter - is also dened. Arthur Devany Essay. After the insertion in film analysis the geometry of the solid objects, boundary conditions are setted: at the edges of x and y (numbers from 1 to 4) they are of Neumann type, while for the user dened electrode (7 and 8) they are of Dirichlet type. At this point the initialization of the plasma and of the solver takes place: since several nonlinear solvers are available, the rst task was to decide which one was more tting our requirements (see section 6.1). The Argon charge density is calculated and the particles are setted to be mirrored along the x axis. Thus it is arthur devany possible to start the iteration loop.
This is necessary since there are two contributions to the electric potential: the accelerating voltage (usually. їЅ''2000 V) of the ion lens and the space charge of the university library thesis ying particles. As this second factor depends on the particles trajectories, which in turn are determined by the total electric potential, an iterative approach has been adopted. The number of iterations can be set in the beginning of the devany essay code: const uint n _iter = 21 Then the i index spaces in the range 0 · niter in order to film analysis, reach the convergence. In the following a brief explanation of the operations executed in every cycle is arthur provided: i = 0 : In the rst iteration the electric potential is calculated taking into account the electrodes contribute only, i.e. for Ѓ = 0. After computing the electric eld, particles are sent. i = 1 : As particles are now present, space charge is calculated and set as a variable in the plasma model; in fact, with IBSimu, plasma is a function of space charge Ѓ, electron temperature Te and plasma potential Up. Then electric potential (and subsequently electric eld) is recalculated, now as a function of both electrodes and ying particles. As the charge density only tools, changes passing from the rst to the second iteration, plasma is calculated only in this step; there is devany no need to recalculate it in the other steps. For i їЅ'їЅ 2: The potential and eld are recalculated and so are the particle trajectories, until both electric potential and space charge converge - i.e. until the dierence for these two parameters between two iteration is nearly zero.
There are dierent function to produce particles, depending on which beam parameters are known: 1. add_2d_beam_with_energy (uint32_t N, double J, double q, double m, double E, double Tp, double Tt, double x1, double y1, double x2, double y2) 38 2. add_2d_beam_with_velocity (uint32_t N, double J, double q, dou- ble m, double v, double dvp, double dvt, double x1, double y1, double x2, double y2) 3. add_2d_KV_beam_with_emittance (uint32_t N, double I, double q, double m, double a, double b, double e, double Ex, double x0, double y0) 4. add_2d_gaussian_beam_with_emittance (uint32_t N, double I, dou- ble q, double m, double a, double b, double e, double Ex, double x0, double y0) where N is the number of particles, J the beam current density (A/m2), q the charge of cognitive-behavioral indian with a clinical case beam particle (in multiples of e) and m the mass (u). For the arthur essay rst two functions, the beam is dened on a line from (x1, y1) to (x2, y2) and it propagates into a direction 90їЅ'їЅ clockwise from the direction of vector pointing from (x1, y1) to (x2, y2); at the beginning the film analysis beam prole is uniform. For the arthur essay rst function E represents the beam energy (in eV ), while Tp and Tt are the parallel and transverse temperature, respectively, in eV. The particle speeds in direction i are sampled from a gaussian distribution with standard deviation dvi = p(Ti · e/m), where Ti is the beam temper- ature in direction i (eV), e is the electron charge (C) and m is the mass of the ion (kg). With the essays third function, particles are own in the positive. x -direction from a starting location (center point) dened by (x0, y0) and the beam spread in the projectional space is made according to KV/hard- edged (Kapchinsky-Vladimirsky) distribution. I represents the beam total current (in A) and Ex the starting energy of the beam (in eV). The beam is made to match Twiss parameters ± (a) and І (b) in projectional direction (y,y'). Arthur. The rms-emittance of the beam is made to match rms (e). Library Thesis. After iterating trajectories (through a special object), electric potential and space charge are recorded in the convergence.dat le; at the end of the simulation process this le can be found in the same folder where the essay source code is. If setted true in the beginning, it starts the last phase, the plotting one; this is the list of film analysis all the plots produced: їЅ' particle traces in the geometry eld; їЅ' zoom of particle traces in the range 0 їЅ'' 1 mm (the zone including the skimmer and the focus point); їЅ' electric potential as a function of x, usually a curve starting near 0 (the skimmer is grounded but there is the plasma potential contribution) and ending at arthur essay їЅ''2000 V (the lens voltage); їЅ' a 3D plot representing the electric potential as a function of x and y in the skimmer region; їЅ' emittance at 50 mm, as a function of y and creative gcse, the angle y0, reporting the values of ±, І, і and ; 39 їЅ' charge density (in C/m3) as a function of x; it is maximum at the beginning - at devany essay the skimmer tip -, then rapidly drops to zero, with a peak in correspondence to epiphany essays, the focus point; їЅ' space charge as a function of x and arthur devany, y in the skimmer region; їЅ' kinetic energies (in eV) of ying particles, in a scatter plot, as a func- tion of particles mass; їЅ' signal intensity, in essay arbitrary units, for each mass, at 8, 50 and devany, 56 mm; їЅ' beam prole histogram plot at 4 and 50 mm; їЅ' a scatter plot for essay writing tungkol, the beam prole, representing the y value as a func- tion of the particles mass, both at devany essay 50 and 56 mm.
40 Chapter 6 Simulation 6.1 Task 1 - solver. The rst task was to nd and compare the dierent available solvers, in order to nd out which one is the fastest. With this aim, the computing time for 1 and 2 iterations has been determined, using one thread only and considering an Argon beam with 20k particles, a beam current of essay writing sa kalikasan 1 mA and a mesh size equal to 100 µm. The outcome of this comparison is the arthur bar plot in Figure 6.1. As it can be seen, the university UMFPACKSolver is the fastest. Moreover this solver can also use multi-thread; this feature makes the UMFPACKSolver the more suitable;1 accordingly, it was used throughout the entire project. 6.2 Task 2 - computing time vs mesh size.
As explained in essay the previous chapter, to calculate the electric potential and the charge density, IBSimu divides the simulation domain in small cells, with uniform size: for each cell UMFPACKSolver solves the problem, i.e. Poisson's dierential equation, and returns a value. So the essays mesh size has a large eect on the quality of the approximation: the smaller the mesh size, the higher the quality of the devany essay simulation is (down to the limit of mesh_size їЅ'' 0, representing the persuasive essay exact solution of the essay problem). The trouble is that it is impossible to decrease the mesh size innitely. Essay Tungkol Sa Kalikasan. The limits are the available memory (with 8967201 nodes - equivalent to a 10 µm mesh size - the system reports a memory allocation error) and the computing time. In fact, the higher the number of nodes, the longer is the time needed to solve the problem. So it is useful to nd a compromise to solve the problem with a good approximation and in a relatively short time. The relation between computation time and arthur, mesh size was investigated for mesh sizes in the range of 15 їЅ'' 300 µm.
In Table 6.1 and Figure 6.2 the data are given and plotted for a 20k particles Argon beam, with a current beam of persuasive essay 20 mA and devany, 41 iterations. 1Twelve threads were available on the computer used. Therapy For An Indian With A Clinical Case Study. 41 Figure 6.1: Computing time for dierent solvers. Table 6.1: Computing time for dierent mesh sizes mesh (µm) no of arthur devany nodes time (s) 300 10197 77.85 250 14625 97.61 200 22761 131.92 150 40303 163.45 100 90321 259.35 50 359841 619.59 40 561801 853.01 30 997957 1343.57 25 1436481 2021.08 20 2243601 3608.08 15 3987023 8676.87 42 Figure 6.2: Computing time as a function of the number of nodes. It seems that the data points plotted have 2 dierent trends: the rst data can be tted with a root function, then (from the 50 µm mesh) the data can be tted with really good approximation through a square function. Essay Tungkol. The functions used to t the two curves are respectively y = a · (1 + x) b (Figure 6.3) and y = A + B · x + C · x2 (Figure 6.4); (6.1) for the rst curve a = 0.32399, b = 0.59039, for the second curve A = 390.06724 , B = 6.03498 · 10їЅ''4 and C = 3.71075 · 10їЅ''10. As the adjusted R2 are, respectively, 0.99772 and 0.99998 these could be considered good ts. As explained before, the devany essay mesh size has an impact on the quality of the epiphany essays results: a too large mesh could lead to a simulation not well representing the reality. In Figures 6.5 and arthur devany, 6.6 beam proles at persuasive 50 mm for dierent mesh sizes are plotted; this trend has been used as judging parameter to arthur devany, test the quality of the results. A brief description of the therapy for an indian with beam prole evolution from the nest mesh to the coarser one is provided, comparing each one with the former. Because 15 µm is the smallest mesh size that can be used, the 15 µm prole has been taken as the plot which best represents the beam prole.
All the other plots, obtained increasing the mesh size, will be compared to this one. The main task is to reach a good compromise between the beam representation quality and the computing time: it is useful to arthur, nd a minimum number of nodes which would guarantee a good nal result to attain the time optimization. Persuasive. In the following (through a dierent geometry) the beam prole was tted with a nonlinear function, taken from the models 43 Figure 6.3: Fit for the rst six points plotted in Figure 6.2. Figure 6.4: Fit for essay, the second part of the data plotted in Figure 6.2. Persuasive Essay. 44 Figure 6.5: Beam proles for mesh sizes between 15 and 50 µm. Arthur Devany Essay. Figure 6.6: Beam proles for mesh sizes between 100 and 300 µm. 45 available in epiphany essays Origin. Before starting the devany analysis it is important to underline that every plot is symmetrical due to creative essays gcse, the applied geometry: the code creates only the upper half of the simulation eld (i.e. the interfaces and arthur, the lens) and then it reects all the elements through a mirror function.
Considering the rst four beam proles (mesh sizes from 15 to 30 µm) one can note that there are no meaningful dierences: increasing the mesh size in this range the beam prole is unaected. As there are small dierences, the number of counts could be considered constant: the dierence between the cognitive-behavioral therapy for an indian with depression case study 15 µm and the 30 µm plot counts is less than 0.2%. Essay. On the contrary, increasing the mesh size to 40 µm, considerable dierences appear: even if the total number of counts is nearly equal, the curve clearly shows an atypical evolution when approximating to the center. A sharp increase occurs in creative gcse the very central range: the devany percentual dierence between the number of personal epiphany essays counts at 0.25 mm and the one at 0.75 mm is about 22%. Further increasing the mesh size the result becomes more pronounced: the devany total number of library counts decreases (till the dierence with the nest mesh is devany greater than 31% - for the 300 µm mesh) and also the shape changes. Tungkol Sa Kalikasan. In the 100 µm plot there is a very high central peak (the ratio between this peak and devany essay, the 15 µm peak is more than 1.5), so the trend is already much dierent. Considering coarser approximations, the outer peaks trend becomes more uniform, while the central one broadens and then splits in two dierent peaks (in the 300 µm histogram the central counts number is very low). In short, large mesh sizes produce unrealistic results and personal epiphany essays, have to be avoided.
In conclusion the best compromise between quality and computing time is represented by the 30 µm mesh. As it has been shown before, approxi- mately 22 minutes are requested for this geometry (for a 20k particles Argon beam with a current of 20 mA and 41 iterations). Furthermore, the space charge density was calculated (data not shown). With increasing mesh size, almost nothing changes close to the skimmer orice. But a peak between. 0.01 and 0.02 m - where the beam is arthur devany focused - decreases when larger mesh sizes, until it disappears at 50 µm. The ratios between the peak height for epiphany essays, three medium meshes, 30 µm, 40 µm and 50 µm, and the smaller mesh used are 60%, 48% and 40%, respectively. Looking for a compromise, the former choice of a 30 µm mesh size can be considered a good solution.
6.3 Task 3 - full 2D geometry switching. As the 2D mirrored geometry could not be considered a good representation of the simulation area (some troubles arise for particles traveling on the x axis), the third task was to modify the code in order to dene a 2D full geometry. This conguration is not using the essay mirror function anymore, as the interfaces and writing tungkol sa kalikasan, the lens are completely dened. After the switch to this new geometry, some simulations were run in order to compare the new computing time with the arthur former one. Table 6.2 shows the time for both geometries. It is important to underline that with the film analysis same mesh size the full geometry has a doubled number of nodes with respect to the mirror 46 Table 6.2: Computing time for 2D mirror and full 2D geometry 2D mirror full 2D mesh (µm) no of nodes time (s) no of nodes time (s) time ratio 300 9956 77.85 24889 161.90 2.0 250 14336 97.61 35840 211.69 2.1 200 22400 131.92 56000 292.98 2.1 150 39822 163.45 99556 385.92 2.3 100 89600 259.35 224000 620.14 2.3 50 358400 619.59 896000 1493.79 2.4 40 560000 853.01 1400000 2164.20 2.5 30 995556 1343.57 2488889 4239.65 3.1 25 1433600 2021.08 3584000 7784.64 3.8 one, because the essay electrodes and essay tools, the simulation eld are dened in the lower part too.
These values are referred to a 20k particles Argon beam, with a beam current of 10 mA and 41 iterations. The last column displays the ratio between the time taken by the full 2D geometry and the 2D mirror. The data ouput was used to evaluate the arthur beam prole for the smaller mesh sizes (50 µm, 40 µm, 30 µm and essays gcse, 25 µm). The dierence between the full 2D and devany, the 2D mirror beam proles gets obvious: they are no more com- pletely symmetrical, because particles are sent randomly. Film Analysis. The member func- tion used in these rst simulations was add_2d_KV _beam_with_emittance(). It adds a 2D beam with dened KV emittance (KV stands for Kapchinsky- Vladimirsky, whose distribution is used for the beam spread in the projec- tional space). It becomes clear that the arthur devany perfect beam symmetry could be achieved only with a large number of particles. Analyzing the film analysis number of counts in arthur the two sections (the left and the right one) of film analysis each plot, it results that the devany essay percentual dierence is essay less than 1%; moreover the bias is anti correlated to the mesh size: 0.54% for 25 µm, 0.45% for 30 µm, 0.27% for. 40 µm, 0.09% for 50 µm. In order to compare the beam prole obtained with the two dierent geometries, one simulation with a 100k particles Ar- gon beam, with a current of 10 mA and a 30 µm mesh size was used. Devany. The comparison with the corresponding 2D mirror result is displayed in Figure 6.7.
The dierences can be summarized in the following way: rst of all, even if the trend at the edge is similar, the midmost increasing is larger in the full 2D case. Moreover, the number of central counts is much higher in the full 2D case: the ratio between the peak heights is about 1.2 and the percentual dierence of the total number of counts between 2D mirror and full 2D curve is about 19%. This result shows the university importance to switch to the new geometry; in fact it clearly proves that the mirror 2D case was aected by some errors in the trajectories calculation for devany, particles in university library thesis the center of the beam, the region we are mostly interested in. Finally, some attempts have been done to t the full 2D beam prole 47 Figure 6.7: 2D mirror - full 2D beam prole @ 50 mm comparison. (using the data obtained with the 30 µm mesh) with a known distribution: as the Gauss t had a R2 adjusted of only 0.99134, it has been chosen a Lorentzian t, obtaining a better result (R2 adjusted = 0.9963). This t is displayed in devany essay Figure 6.8. Olney, Chen and Douglas  measured gas ow proles downstream the skimmer using an impact pressure probe. It consisted of a small 0.254 mm diameter orice in a at cognitive-behavioral for an with case study plate at the end of a 6.35 mm od tube that was connected to arthur, a pressure gauge. The gas ow proles were measured for an interface arrangement with a rst stage pressure (P1) of 3.3 Torr and a sampler-skimmer spacing of 6.4 mm; this interface is similar to that used on commercial ICP-MS systems.
Using French calculations , they found the density o the centerline: n(r, їЅ') n0 = B cos 2 їЅ'їЅ' 2C r r0 їЅ''2 (6.2) where їЅ' is the polar angle between the centre axis and tools, the point of interest, r0 the orice radius, r the distance of the probe from the arthur source (r2 = x2 p +z 2 p , where zp is the essay writing tungkol sa kalikasan distance of the probe from the centerline) and devany, B and C are, respectively, 0.643 and 1.365 (for Ar). The impact probe was scanned radially across the beam at 13 mm down- stream the skimmer; Figure 6.9 shows the essays free jet gas ow prole obtained from impact pressure measurements made at several distances from the centerline. Arthur Devany Essay. Considering the geometry and settings dierences between the film analysis case on study and the work by Olney, Chen and devany essay, Douglas, the beam prole obtained with IBSimu is consistent with the one shown in their work. 48 Figure 6.8: Lorentz t. Figure 6.9: Free jet proles calculated - dotted line - and measured - lled circles; the density eld of equation 6.2 is multiplied by an additional factor. cosїЅ' to account for the decrease in the apparent area of the probe (solid angle) viewed from the source orice as the probe moves o-axis . 49 6.4 Task 4 - Up and Te investigation. The optimum mesh size for a mirrored geometry was determined to be 30 µm.
Since with a full 2D geometry the number of film analysis nodes doubles, some simulations have been done to devany, see if a mesh bigger than 30 µm guarantees good results. It has been found that using a 50 µm mesh the beam prole does not change; so for the following task, this mesh size has been used. The aim was to analyze the eect of plasma potential (Up) and depression study, electron temperature (Te) on the beam prole. Devany Essay. These parameters have been chosen because they dene the university plasma itself and they represent the arthur devany essay main contribu- tion to the particles trajectories. After few simulations it became clear that it was necessary to creative, change the particle seeding function; we soon realized that add_2d_KV _beam_with_emittance() did not take into account the charge density and arthur devany, it was initializing the plasma potential to a Null value (no dierences were seen varying the plasma potential). However, the beam proles calculated in the former task were correct, because with such a high current beam the space charge eect was signicant. So, the new used function was add_2d_beam_with_energy(), which adds particles with kinetic energies sampled from a gaussian distribution. Film Analysis. Unfortunately, it was not possible with this new function to arthur, set a beam current greater than 5 µA; for higher values, particles are grouped in bundles (needless to say that this result can not be true). University Library Thesis. So, with a 100k particles Argon beam, a current of 5 µA and 21 iterations (after having checked the con- vergence) some runs have been done with dierent plasma potential values: 0.1, 0.2, 0.5, 1, 2, 5, 8, 10, 15 and 20 V. The outcome beam prole does not have any signicative dierence until 1 V, then, increasing the plasma po- tential, the number of counts and the peak height decrease. Moreover, above.
10 V all plots are almost identical, both in shape and number of counts; as a consequence it does not make sense to investigate low or high intervals and the study was concentrated on the range 2 їЅ'' 10 V. This interval of arthur survey is in a good agreement with the essay writing sa kalikasan available literature data . The trend shown in Figure 6.10 is probably due to the space charge eect: it becomes more intense with a higher potential, especially in the center of the beam, where the essay number of particles is high. So, increasing. Up, more and tools, more particles are lost on the skimmer walls; in a calculation for 10 V, this number could be near to devany, 80% of the total number of starting particles. Essay Writing Sa Kalikasan. With a low plasma potential value, some particles are colliding on arthur essay, the skimmer wall too, but this number is smaller - with Up = 2 V it is about 40% - because the beam is spreading less than in the case of high Up. Regarding the charge density plot, its trend does not change. The only film analysis, dierence is in the peak corresponding to the focus point: its height halves from 2 to 6 V and then remains constant until 10 V. Arthur. In conclusion of the plasma potential evaluation, one can say that the sharpest beam proles are achieved at lowest potential, in particular at Up = 2 V. A similar study has been conducted for the electron temperature, be- tween 2000 and 8000 K (corresponding to 0.259 and 1.035 eV, respectively, using the equipartition theorem). The number of publications inquiring this 50 Figure 6.10: Beam proles for Te = 5000 K and dierent plasma potentials. topic is considerable ; the reported values range between. 1000 and 16000 K, depending on many factors (distance from the load coil, radial position, dry or wet plasma, introduced analyte and radio frequency power setting). The results for dierent plasma potentials (summarized in personal Figures 6.11 and devany, 6.12) show a dierent behaviour. At low Up, increasing the electron temperature results in a rise of counts at the boundaries and a decrease in creative essays the center.
Probably due to a greater thermal agitation, the arthur beam prole becomes smoother (this attening is more uniform than the one obtained increasing Up). On the contrary, if the potential is high the plot is already at and by varying the university library thesis temperature nothing changes. The best solution would be having a sharp peak (like the one obtained for arthur devany essay, the lower temperature) with a high number of persuasive counts (as it happens for high Te). So choosing the best electron temperature is not easy: both 2000 and 8000 K could be considered good solutions. In the charge density plot, increasing the electron temperature, the peak corresponding to the focus point moves slightly toward the skimmer, while its intensity increases and the full width half maximum (FWHM) gets smaller. These changes are small, so they could be neglected. The best conguration would be a focus point far away from the skimmer, in order to minimize the space charge eect. In order to better understand how the plasma potential and the electron temperature aect the arthur devany essay simulation and, above all, to nd the combination that gives the best result, three 3D plots have been done, representing the total number of counts, the peak height and the FWHM as a function of the library thesis two fundamental parameters. The results are depicted in Figures 6.13 51 Figure 6.11: Beam proles for arthur devany, Up = 2 V and dierent electron temperatures. Figure 6.12: Beam proles for essay, Up = 6 V and dierent electron temperatures. 52 Figure 6.13: Number of counts as a function of Up and Te. to devany, 6.15.
As evaluated before, it was shown that Up = 2 V is the best plasma potential. Film Analysis. Regarding the electron temperature, two dierent values could be good: with Te = 2000 K the peak is narrow (lowest FWHM) and arthur essay, his height is maximum. On the other hand, with Te = 8000 K there is still a good FWHM and the number of counts is increased. The good quality of essay writing these two combinations (Up = 2 V - Te = 2000 K and Up = 2 V - Te = 8000 K) is underlined in the plot represented in Figure 6.16, obtained with a combination between number of counts and FWHM. From the literature review it can be postulated that 2000 K is essay a too low value for persuasive essay tools, the present case.
In fact the electron temperature in devany essay a Fassel torch is around 10000 K and personal essays, the plasma bulk properties remain unchanged as it proceeds through the sampling orice ; the only signicant electron loss at the walls of the sampling plate is conned to distances of the arthur devany order of one Debye length - 10їЅ''2 to epiphany essays, 10їЅ''3 mm. In conclusion for the next simulations the following values were adopted: Up = 2 V and Te = 8000 K. 6.5 Task 5 - dierent masses. Once completed the Argon beam simulations, the devany essay next step was to intro- duce other particles, to see the particles beam prole. Since the plasma is constituted by Argon, the number of the other masses is so low that their contribution to the electric potential is nearly negligible. So, to speed up the simulation, it was convenient to simulate only tools, Argon in devany essay the rst runs 53 Figure 6.14: Peak height as a function of Up and Te. Figure 6.15: Full width half maximum as a function of sa kalikasan Up and Te. 54 Figure 6.16: (number of counts)2 / full width half maximum. (to calculate the resulting electric potential) and then, in the last part, all the other particles. This topic will be discussed in arthur detail in cognitive-behavioral for an a clinical case the next section.
The rst set of simulations was aimed to study how the number of counts is arthur aected by essay writing, the mass of the projectile at dierent potentials. The array of particles used (excluding Ar) was: 1, 5, 10, 20, 30, 50, 60, 80, 100, 140, 180, 220 , 260, 300 amu. 100k particles per arthur essay, species were seeded, with a 50 µm mesh, Te = 8000 K and for dierent plasma potentials: 2, 3, 4, 6, 10 V. The signal intensity per species, downstream the lens orice, is given in Figure 6.17. The trend obtained is logarithmic for each potential, even if with in- creasing Up the university library thesis curves are attening. A good t has been found: the arthur essay curve.
y = aїЅ''b·ln(x+c) always provides R2 adjusted greater than 0.999. Compar- ing the gcse plot in Figure 6.17 with the devany essay one obtained at 50 mm (just before the lens orice) and essay writing sa kalikasan, shown in arthur Figure 6.18 clearly indicates that a lot of particles are lost on the lens walls, as the maximum intensity halves. Moreover, the most intense lost is for low mass particles: considering the intensity ratio between 50 and 56 mm, it passes from 7.57 for m=1 to 3.87 for m=100 to essay writing sa kalikasan, 2.08 for devany, m=300. This could mean that lower masses are mostly at the boundary of the university thesis beam - whilst higher masses are in the centre - or that the spread is higher for light particles - making the prole nearly at. Devany Essay. In the following this particular distribution was studied through the beam prole plots. Considering instead the signal intensity per species for dierent electron temperatures, the curves are not aected and library thesis, the intensity dierence is nearly negligible (see Figure 6.19). Increasing the arthur electron temperature, the 55 Figure 6.17: Signal intensity per mass @ 56 mm for for an indian adolescent case, Te = 8000 K and dierent plasma potentials.
Figure 6.18: Signal intensity per mass @ 50 mm for Te = 8000 K and dierent plasma potentials. 56 Figure 6.19: Signal intensity per mass @ 56 mm for Up = 2 V and dierent electron temperatures. number of arthur devany counts also increases, in a non linear way: higher the mass, bigger the dierence from essays, two dierent temperatures is. Nevertheless the gap is quite small: for m=300, the percentual dierence between 5000 and 12000 K (in respect to the lower Te) is about 6. The eect of an electron temperature changing on the number of counts for m=300 is shown in Figure 6.20. In order to see in detail how plasma potential and electron temper- atures aect the beam prole, some simulations have been run with the three masses (in addition to arthur devany essay, Ar) which give an overall view on for an with a clinical study, all possible particles: 1, 150, 300. The result is consistent with the one obtained in case of devany Argon: it validates 2 V as the best plasma potential and the trend for dierent Te is equivalent to the one showed in the previous section. Cognitive-behavioral Therapy For An Adolescent With Depression A Clinical Case. As it resulted from signal intensity plots, the number of counts for lower masses is low. Arthur Devany Essay. Running the same number of particles would make a comparison between beam proles of mass 1 and 300 impossible: the former one would be completely at compared to the other. As the essay tungkol sa kalikasan beam prole evolution (changing Up and Te) is the same for mass 40, 150 and 300, it is reasonable to presume this trend is identical for mass 1. The beam prole was studied in arthur detail for dierent electron temperatures (Figure 6.21). As it is shown for m=150, increasing Te, the therapy for an central peak decreases and broadens until 6000 K, then, it starts increasing again. Moreover, while its central width does not change, the boundary number of counts progressively decreases and so the arthur transition from the boundary to the centre becomes sharper (the area under the curve being constant). The only dierence with 57 Figure 6.20: Signal intensity @ 56 mm for m = 300 and dierent electron temperatures.
Figure 6.21: Beam prole @ 50 mm for Up = 2 V, m = 150 and dierent electron temperatures. 58 Figure 6.22: Beam prole @ 50 mm for epiphany essays, dierent masses, for arthur devany essay, Up = 2 V and. Te = 8000 K. argon is cognitive-behavioral depression a clinical case right in arthur this area: in the analyzed case the boundary number of counts drops to personal, zero (this feature is even more noticeable for m=300) at about 4 mm from the centre, giving to the prole a more sharp shape. This phenomenon has been more deeply investigated. Arthur. With a set of projectile similar to the one used for the rst plots, the beam prole for each species has been represented - for Up = 2 V and. Te = 8000 K. For low masses it was necessary to therapy indian with a clinical case, run more particles in devany essay order to have a good statistics. Especially in this plot the mass discrimination is obvious: most of the therapy adolescent study low species are lost on the skimmer and lens walls, so their contribute is about one order of magnitude smaller for high masses. As observed before the arthur essay beam prole progressively changes: while Argon (previously studied) can be tted with a lorentzian curve, increasing the mass, the prole loses its tails and acquires a better dened shape.
Starting from creative essays gcse, m = 160, the boundary number of counts drops to zero; in arthur other words, high masses are well focused. This is an important result, because it means that all these particles will pass through the lens orice. To better visualize the results it was convenient to university, represent the beam prole ratio between a given mass and mass 120. Arthur Essay. This value was choosen because its curve is the essay rst having nearly zero counts at the edge. As in the analyzer enters just the essay central part of the beam, high boundary ratios were not take into for an adolescent with case study, account. Arthur Essay. The plot in Figure 6.23 clearly shows the mass discrimination as a function of atomic mass and radius (radial distance from the beam center - dened as 0.02 m). This plot underlines how much sharper the beam proles are for high 59 Figure 6.23: Counts ratio @ 50 mm for Up = 2 V and Te = 8000 K. masses: it is important to notice that the resulting hollow for low masses does not mean the total number of counts in personal essays the center is lower than at the boundaries, but just that the devany number of counts is personal epiphany increasing slower (to the centre) for low than for devany essay, high masses. 6.6 Task 6 - iteration settings. As anticipated, with many projectiles it is convenient to split the iteration phase in two parts: in the initial runs only Argon is seeded, while in the last all the other particles (dened in the masses array) are added. Film Analysis. In fact the one that contributes more to the total electric potential is Argon, while other particles have a negligible impact on it. Some simulations have been run to answer the following questions: їЅ' With a xed number of iterations, does the beam prole change vary- ing the number of initial and nal iterations' How' Is the computing time aected' їЅ' How many particles are needed to y in essay the last run(s) in order to have a good compromise between a good beam prole and essay writing sa kalikasan, a short computing time' їЅ' How many particles are optimal for the rst runs' The rst comparison was aimed to see which changes occur when the number of iterations in arthur devany which all particles are sent vary.
With a xed 60 Figure 6.24: Electric potential dierence as a function of film analysis iteration number for devany, the analyzed cases. number of total iterations (25), dierent combinations have been tried: (case 1) 10+15, (case 2) 15+10, (case 3) 23+2, (case 4) 24+1. The rst parameter checked was the electric potential convergence: in Figure 6.24 the electric potential dierence is shown for the considered cases. There are two points that have to be underlined: (i) the y axis has a logarithmic scale - this means that the initial decrease is sharp - and (ii) in case4 the electric potential dierence is not calculated after ying all parti- cles - because in the code the particles are sent after the electrical potential is recalculated. 2 The increase in each curve is due to the addition of other species: considering that the total electric potential is 2000 V, this oper- ation does not signicantly aect the result. To validate this hypothesis, the obtained beam proles have been compared to the one obtained in the rst case.
With 15 + 10 iterations the result is identical (exactly the same number of counts per interval) to the rst one, while case 3 and 4 have some small dierences, even if the prole shape remains unchanged. As the com- puting time decreases from 34 (case1) to writing essays gcse, 29 (case2) to arthur devany, 19 minutes (case4), the conclusion is the epiphany essays following: reducing the arthur devany essay number of tungkol sa kalikasan nal iterations does not signicantly aect the nal result; the dierence is negligible in all cases even for particles with low mass - in devany which case the total number of counts is sa kalikasan low. This result has been validated also in arthur devany the case of 20k particles in the rst runs and 100k in the last one. Then, two simulations with a dierent nal number of particles have been performed: 50k and 100k. For low masses (m=1 in cognitive-behavioral indian adolescent with depression a clinical the analyzed 2So case4 represents the convergence for Ar only. 61 Figure 6.25: Ratio between the beam prole @ 50 mm with 50k particles and the one obtained with 100k particles, for m=1. case) the number of particles reaching the end of the simulation eld is low and random uctuations aect signicantly the beam prole. As the uctuation amplitude does not change passing from the rst to the second case, the former one represents a coarse approximation (as clearly indicated in Figure 6.25). Increasing the atomic mass the devany essay number of counts increases too and the background noise becomes negligible. So it is better to split the following discussion in two cases. For high masses the solution is likewise the essay writing tungkol sa kalikasan prece- dent: running with 50k instead of 100k particles is a good approximation and arthur essay, the advantage is that the simulation time is reduced - halved in library thesis the case of 10 + 15 iterations.
To see how much time is earned running less particles in the last run only, two simulations have been done, with 50k particles at the beginning and devany essay, 50/100 in the last run. The dierence is about 15%, but is not really signicant as the total time needed is around 20 minutes (19 min in the rst case and 22 min in the second). The situation is critical for low masses: running few particles in film analysis the last run(s) does not provide a good statistics. Therefore, it is convenient to run more particles (in the arthur devany last run only), even if it takes a bit more time, to film analysis, have a better statistic. To conclude this study, the last parameter to devany, change was the number of particles in the rst runs: 3 the simulation result for university, 20k particles was compared to the one obtained for 50k - with 100k particles in the last runs 3A variation in the number of Argon particles does not change the total charge density (it is arthur essay dened as constant); the only quantity changing is the charge density carried by each particle. 62 - rstly for 10 + 15 and then for 24 + 1 iterations. Creative Writing Gcse. In both cases there are no dierences between the two simulations - for the case 10 + 15 iterations every single beam has the same amplitude as in the other case and similarly for 24 + 1 iterations. In the rst case even the computing time does not importantly change, probably because the time needed to seed only Argon is smaller compared to arthur essay, the one for university, all particles.
On the contrary, the dierence is notable in the second case: instead of 22, just 14 minutes are needed. Anyway, it is important to underline that this is arthur devany essay not a general result: sending more species, the time needed for the last iteration will increase, while the time for persuasive essay, Argon does not change. So the percentual time earned will decrease with the arthur devany total number of species increasing. Anyhow decreasing the number of Argon particles does not aect the beam prole quality, so it can be reduced to 20k. The following list summarizes the settings that optimize both the essays results quality and the computing time: їЅ' number of arthur iterations: 24 + 1; їЅ' number of particles in the last run: 100k; їЅ' number of particles in the rst runs: 20k. 6.7 Task 7 - Cadmium. In order to compare between simulation and experimental results, Cd can be used, with three of its isotopes: 110, 111 and film analysis, 114. Through this com- parison it is possible to nd out the plasma fundamental parameters that characterize the used instrument. In the following a short experimental description of the implantation and measure of arthur essay ions number is given.
In order to personal epiphany, detect the radial distribution of Cd - this element is used because it shows a signicant radial dependence -, an devany, Aluminium target was placed at the base of the extraction lens. Thus implanted ions should represent the spatially resolved composition of the extracted ion beam. The target is analyzed by cognitive-behavioral for an depression a clinical case study, Laser Ablation ICP-MS after implantation, performing a line scan from the rim region (A) toward the essay center of the target (B), as shown in Figure 6.26. The spacing between two adjacent ablation spots (150 µm) is film analysis sucient to have a high spatial resolution density and, in the same time, to avoid overlapping . Because laser ablation removes material in the range of arthur essay several hundreds of nanometer per pulse, a complete removal of the im- planted ions is ensured. The calculated ratio 114Cd/111Cd in a single data set from cognitive-behavioral therapy for an a clinical study, a representative Cd isotope ratio analysis is represented in Figure 6.27, with the corresponding transient signal for 114Cd. Since laser ablation provides spatially resolved information on the im- planted matter, a relation between Cadmium signal and ion beam intensity has to be assumed in order to deduce the ion beam prole. However, the sputtering due to the high Ar-beam current jeopardizes this relation; the 63 Figure 6.26: Sketch of the Al target assembly mounted in the Neptune MC- ICP-MS instrument. The dotted line denes the area exposed to the ion beam and arthur essay, the position of the line scan is given by the black line . Figure 6.27: 114Cd/111Cd isotope ratio (open circles) and signal intensity . 64 Table 6.3: Set of simulation run run number Up (V) Te (K) 1 2 8000 2 3 5000 3 4 10000 4 8 5000 5 2 5000 6 2 10000 signal intensity is high in an annulus around 1 mm from the essay writing sa kalikasan centre and devany, then decreases when moving toward the tools centre.
This drop coincides with optically observed material defect; at this location the low signal is probably caused by removal of devany essay material by sputtering. To plot the essay tungkol ratio 114Cd/111Cd against the distance from the centre, some simulations have been run, with the following conguration set: їЅ' 35 iterations, 20 with Argon only + 15 with all the particles, їЅ' masses array = 110, 111, 114, їЅ' beam current = 5 µA, їЅ' mesh size = 50 µm, їЅ' dierent plasma potentials (Up) and arthur, electron temperature (Te). As explained before, the aim of these simulations was to nd a beam prole as similar as possible to the one shown in Figure 6.27. To reach this achievement, Up and Te were varied in cognitive-behavioral therapy for an with case study their validity interval. The parameters for each run are summarized in devany Table 6.3. Beam proles have been plotted; increasing Up the trend becomes at, so Up = 2 V is the setting that resembles the real value best. Regarding the electron temperature, its contribute is not signicant as the Up is. Since the film analysis ratio obtained with the simulation is slightly dierent from the experimental one, identifying the arthur essay electron temperature real value results more dicult. In Figures 6.28 to cognitive-behavioral for an indian depression case study, 6.30 ratios are given for three values of Te. Devany. It seems that the intermediate case - 2 V and 8000 K - is the closer to reality, even if the shape diers for cognitive-behavioral, some features.
While the experimental plot rapidly decreases in devany the center and personal essays, its trend is clear, the simulated one decreases slowly; at the edge, it can be seen the same low point it can be found at 6 mm in arthur devany Figure 6.27 - even if in Figure 6.29 is at dierent position, 2 mm closer to tools, the center. The trouble is that data processing could give rise to dierent explanations, depending on which bin size is choosen plotting the histogram. More accurated and resoluted simulations are necessary in order to make this comparison more precise and reliable. 65 Figure 6.28: 114Cd/111Cd ratio for devany, Up = 2 V and Te = 5000 K. Figure 6.29: 114Cd/111Cd ratio for film analysis, Up = 2 V and Te = 8000 K. 66 Figure 6.30: 114Cd/111Cd ratio for Up = 2 V and Te = 10000 K. Arthur. 67 Chapter 7 Results and epiphany essays, discussion The present work wants only to arthur devany essay, be a starting point in the understanding of the extraction process: in creative writing essays the future, on one hand more simulations and with dierent softwares can be performed and on the other some im- provements can be applied to the instrument.
IBSimu already represents a better simulation package compared to SIMION; with the latter, taking into account the space charge eects is dicult and devany, really impractical. Nev- ertheless, IBSimu still has a liability: it is impossible to y neutral particles and then simulating the scattering process between neutrals. Personal Essays. For this rea- son the group of arthur devany Kivel is developing new simulations, both with dsmcFoam1 and with PI-DSMC (Parallel Interactive Direct Simulation Monte Carlo). Both this programs use the probabilistic (Monte Carlo) simulation to under- stand the uidodynamics of the free jet expansion. DSMC has been already documented in some articles  ; the particular implementation of the algorithm is called FENIX. Epiphany. As the solver in IBSimu, the Monte Carlo al- gorithm models the gas ow by dividing the simulation region into small spatial collision cells, each one smaller in the extent than the local mean free path. Then, each particle is given a random chance to arthur devany, collide with its nearest neighbor in its collision cell, using the collision statistics appropri- ate to the density and temperature in the cell. A more detailed description of the algorithm can be found elsewhere  . The aim of the FENIX simulation would be to make a more detailed calculation of the ow in writing tungkol sa kalikasan the ICP-MS, not limited to the region downstream the skimmer anymore, but in the whole extraction interface. In this approach the study of the devany jet ex- pansion reported in chapter 4 is essays gcse fundamental to make a comparison between simulated and theoretical results and in order to validate the model. This new simulation software is fundamental even for another reason: applying a modest voltage to the skimmer could improve the transmission eciency.
Usually about devany 10% of the total number of ying particles is lost on the skimmer walls and the trouble is library that most of these particles are the lightest. Electrically oating one or both the cones at various potentials could accelerate the ions and therefore reduce this phenomenon. It has been found, with IBSimu, that having the skimmer at arthur devany few volts would focus the personal epiphany essays 1dsmcFoam is part of the open source CFD package OpenFOAM. 68 Figure 7.1: Sketches of the devany three used arrangements . Film Analysis. beam; the arthur devany downside of this action stands upstream the skimmer, where ions would see a repulsive force. For this reason simulating the entire extraction interface with DSMC is necessary, in order to personal, understand the devany beam behav- ior. Essays. Hu and Houk  applied modest DC voltages (+10 to +50 V ) to both the sampler and devany essay, the skimmer or, alternatively, left the sampler oating - i.e., deliberately not connected to any voltage source or to gcse, ground - with the skimmer biased. Three specic arrangements (shown in gure 7.1) were studied: (a) sampler and skimmer biased together, (b) sampler oated and skimmer biased and arthur devany essay, (c) sampler grounded and skimmer biased. The results are depicted in cognitive-behavioral for an adolescent with a clinical case study gure 7.2 with Co+ as analyte.2 There is an improvement in each case: by devany, a factor of 4 (modestly) by applying the film analysis same DC voltages - about 20 V - to both sampler and skimmer (A), by essay, a factor 5 of in case C, and by a factor of 6 by oating the sampler and applying a DC voltage of 30 їЅ'' 40 V to the skimmer. It results that conguration b is the one which gives the higher signal; 2Relative sensitivity refers to the sensitivity obtained for a given element with one of the new interface arrangements divided by that obtained for the same element with the conventional interface. 69 Figure 7.2: Relative Co+ sensitivity as a function of biasing voltage .
Table 7.1: Molar sensitivities for various elements expressed in terms of for an atomic concentration  molar sensitivity (counts/ (s · mM)) interface arrangement Co Rh Ho m/z = 59 m/z = 103 m/z = 165 conventional interface 5.6 · 107 8.5 · 107 2.2 · 108 interface b 3.5 · 108 3.3 · 108 3.0 · 108 in arthur Table 7.1 molar sensitivities for various elements are compared. Therapy Depression A Clinical Case Study. Another advantage given by this conguration is the reducing of the mass bias: in fact, the sensitivity is improved for Co+ by a much greater factor than is in the case for arthur, the heavier Ho+. Even if it seems that the ions have a sucient kinetic energy to ow through the sampling cones, some simulations should been run in order to check what happens upstream the skimmer: applicating a positive potential could repel ions and prevent them from passing through the orice. So in this case the simulation eld has to be extended, in university order to start the beam in correspondence to the sampler. 70 Chapter 8 Conclusions As explained in the introduction, the aim of this work was the optimization of the ion extraction from the ICP.
IBSimu turned out to be a suitable and useful instrument for this purpose, thanks to its versatility and easiness of use. Essay. It calculates the comprehensive electrci potential dividing the simula- tion region in small meshes or cells. Once chosen the fastest solver among the many available, the mesh size has been determined in order to have a good compromise between results quality and computing time. At the beginning, the code describing the simulation eld was characterized by a 2D mirror geometry; due to some problems, switching to a full geometry came out to be convenient. Then the main section of the work started: the investigation on how the beam prole changes upon varying the plasma main parameters, i.e. the plasma potential and cognitive-behavioral therapy for an indian with depression case, the electron temperature. Changing the plasma potential, noticeable dierences were observed in the beam prole only in arthur the range between 2 and 10 V; increasing Up more particles collide on the skimmer wall and then the beam prole decreases in intensity attening. Film Analysis. The electron temperature has a less considerable eect and, particularly, its consequence depends on the plasma potential value: if Up is low, increasing. Te the trend attens, while if Up is high nearly nothing changes.
Since the aperture to the mass spectrometer is 4 mm wide, the couple of values. Up = 2V and Te = 8000K has been chosen in order to have a sharp peak with a high number of counts. This result has been obtained ying only Argon ions, but it has then been ratied simulating a beam with many species. One of the most severe problem in the Inductively Coupled Plasma Mass Spectrometry is mass discrimination, that is the essay preferential lost of the beam particles with a low mass in respect to heavier species. This phenomenon has been characterized and essay, then the arthur eect of a plasma potential and elec- tron temperature variation has been studied in order to see if it determines any advantage. While only small and personal essays, negligible dierences occur changing. - caricare i tuoi contenuti.
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10 Resume Tips From A Legal Recruiter. Ed. note : This is the latest installment in devany, a series of posts on lateral partner moves from epiphany, Lateral Link’s team of expert contributors. Abby Gordon is a Director with Lateral Link’s New York office. Abby works with attorney candidates on law firm and in-house searches, primarily in New York, Boston, and Europe. Prior to joining Lateral Link, Abby spent seven years as a corporate associate with Cleary Gottlieb, focusing on capital markets transactions for Latin American clients in New York and for the last five years for European clients in Paris. A native of Boston, Abby holds a J.D., cum laude, from arthur devany, Georgetown University Law Center and a B.A. in government and romance languages, magna cum laude, from Dartmouth College. Abby also worked with the International Rescue Committee as a Fulbright Scholar in Madrid, Spain. She is a member of the New York Bar and is fluent in French and Spanish (and dabbles in Portuguese and Italian). As a legal recruiter, I review numerous resumes each week in an effort to assist my candidates with the substance and university library presentation of their one-page life summaries.
Here are ten tips based on the most common problems I see and questions I am asked: 1. Assume no one will read your resume word-for-word. Picture your interviewer pulling your resume off the printer and reading only what he can in devany, the time it takes to walk back to university thesis, his office. You need to make the most important stuff jump off the page. Use bold. Use bullet points. Use headings.
Give some thought to the format that will convey the necessary information in the most logical way. Arthur Essay? 2. Be concise and make every word count. Epiphany? This is related to Tip #1. You want the arthur essay, most important stuff to jump off the page, but every word on your resume should serve the purpose of showing that you are the best candidate for the specific job. It’s just one page. 3. Tailor your resume to the specific job. Keep in the forefront of your mind that you are applying for a legal job. Do not view “updating” your resume as merely adding to the same document you first created 20 years ago. Writing? Delete information that is no longer relevant #8212; remember, every last word should serve the purpose of arthur essay, getting you this job.
If you are applying to 10 general litigation openings, one version may be just fine. But if you are applying to some general litigation spots and some patent litigation spots, you may want to have two versions of your resume, with each tailored to library thesis, the specific opening or category of opening. 4. Be sure you can talk intelligently about every last thing you include on arthur essay, your resume. If you can no longer remember the personal essays, main argument of your senior thesis from college, delete it from your resume or refresh your memory before any interviews. You also must be prepared to talk about the any legal matters you claim to have worked on, including about the underlying legal issues.
5. Arthur? When describing your legal experience, give concrete examples . Essay Writing Tungkol Sa Kalikasan? Instead of merely asserting that you are a capital markets lawyer, note that you “Drafted the underwriting agreement as lead associate representing the arthur essay, underwriters in the offering of writing tungkol sa kalikasan, $300 million in floating rate notes by a large U.S. manufacturing company.” Even if you have a separate representative matters sheet, it may be helpful to include a few bullets points showing this experience in your actual resume as well. And remember from Tip #2, every word counts. Don’t use neutral words where a more positive word could convey more meaning. For example, which is devany more powerful, stating that you “worked on” a project or that you “successfully implemented” a project? 6. Be sure all information is essay writing tungkol sa kalikasan up-to-date. If you are no longer on a committee, delete it from your resume or indicate the proper dates.
Change the verbs (“represent,” “draft,” “negotiate”) from the descriptions of your prior jobs to the past tense (“represented,” “drafted,” “negotiated”). No longer fluent in French? Be accurate in the assessment of arthur, your language ability as of film analysis, today, not as of mid-way through your junior year abroad. 7. Devany Essay? Additional Information: Space is a commodity, but you should still make room for two or three lines that show you are a human being and not just a robot. Persuasive Essay Tools? Include a few interests (but be sure they are real interests of yours and not aspirational hobbies). Maybe you and arthur devany one of the interviewers will find you have a hobby in common.
If nothing else, this “fluff” gives interviewers some material for a few softball questions to break the writing sa kalikasan, ice or end the interview on a lighter note. Aside from devany, true interests/hobbies, include language abilities, bar admissions, and memberships/affiliations so long as you are an active and not just passive participant in these organizations. Remember the tungkol, essential test: “Can you talk intelligently about it if asked?” If someone asks about your membership in an alumni network, will you state proudly that you assisted in devany essay, raising $500,000 in alumni contributions for a scholarship fund or will you cower in gcse, your chair and confess that you are on devany, the e-mail list for the committee but have yet to attend a meeting? 8. Education first or work experience first? This is a common question. Remember Tip #1 #8212; you want the library thesis, most important stuff to jump off the devany essay, page. So if you went to a top law school, you may want to creative essays, list education first.
If your law school was not as highly ranked but you somehow landed a job at arthur essay Wachtell, list work experience first. In the writing, case of arthur devany essay, a tie, I’d go with work experience first. 9. The squint test : It seems a bit unsophisticated but it works. Tape your resume to a wall about creative essays gcse, 10 feet away or just hold it far out in front of arthur essay, you and for an indian adolescent depression case study squint. Does the balance of black and white on the page make your eyes happy? Is there much too much dense text?
Or way too much white space? If you’ve ever strung lights on a Christmas tree, it’s the same principle. Arthur Devany? Squint and then follow your instincts. 10. Proofread your resume carefully. Then proofread it again. Then ask a friend to persuasive, proofread it. And another friend. And your legal recruiter. Then proofread it again. Nothing screams “Don’t hire me!” like a glaring typo or spelling mistake.
10?. Arthur Devany? Here’s a freebie. It’s not the gcse, most important tip unless… well if it is, you know who you are. You know that photo of devany essay, you in the Bahamas in thesis, your bikini? Shirtless? You remember how you uploaded it to your Google profile? And now you list your Gmail address on arthur, your resume? Well guess what… When I am e-mailing you at your Gmail address, yes, I can see that photo of you in the right-hand sidebar on my screen. University? If I can see it, so can the recruiting coordinator and devany essay so can the partner at the firm where you’re interviewing.
Oh, and one more thing: your Twitter feed will also now show up on the right-hand sidebar. I’m not asking you to cognitive-behavioral for an with, stop using social media. But if you are indiscriminate about your tweets, think about devany essay, setting up a separate e-mail address for the job search process. Film Analysis? There is not just one right way of devany essay, designing a resume. But there are wrong ways. Look at models but don’t just copy someone else’s.
This singular piece of paper is your key to getting your foot in the door in film analysis, the next step of your career… or not. Arthur Essay? It’s worth spending a few extra hours getting it right. Lateral Link is one of the top-rated international legal recruiting firms. With over persuasive essay tools, 14 offices world-wide, Lateral Link specializes in placing attorneys at the most prestigious law firms in arthur essay, the world. Managed by former practicing attorneys from top law schools, Lateral Link has a tradition of hiring lawyers to execute the essay writing sa kalikasan, lateral leaps of practicing attorneys. Click ::here:: to find out more about us. Sign up for arthur, our newsletter.
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What Were You Thinking? Equifax GC Probed For Executive Stock Sales Before Public Learned Of Breach. Law firms blow a lot of rhetorical hot air affirming their commitment to achieving gender diversity in the workplace. Yet, despite some isolated efforts to hire and retain more female attorneys and promote more women into partnership, little tangible progress has been made to improve the position of women in the profession… Location: Any Stoel Rives LLP , United States. posted by Stoel Rives LLP Jr. Emerging Companies Corporate Associate. Location: San Francisco, California. posted by Kinney Recruiting LLC Legal and Compliance Associate. Location: New York, NY, United States. posted by Autonomy Capital Develop software for tax and legal application. Arthur Devany Essay? Work at home. Enjoy life. Library Thesis? Location: Telecommute, MA. posted by devany essay Family Law Software Health Care Attorney 7 + years experience, No Book Necessary.
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15 Resume Mistakes That Can Cost You a Job. As a self-employed writer and entrepreneur, I don’t normally have much to do with resumes. I do maintain one of my own, but it’s more of an academic CV that gets used only for academic applications. Otherwise, I’ve never really applied for a job or had a use for my own job-applying materials. I don’t do much hiring either, but every once in a while I get the chance to devany sort through applications for non-profit jobs. I got that chance last week, and I learned a lot through the library experience. More than anything else, I learned a few things not to do if I ever apply for a job. And if you’re in arthur devany essay that position, pay attention to this essay – I can’t guarantee that everyone will process resumes the way I do, but I’d expect that a lot of these principles will be universal.
How to Immediately Lose Your Chance at the Job. Roughly 20 candidates submitted applications for film analysis, the job in question, and at least a third were completely off the mark. The funny thing is devany that almost all of these candidates had college degrees and a fair amount of creative writing essays, experience, but so many of them made what seemed to me to be basic, no-excuse mistakes. Because common sense is not always common, I thought I’d share with you some of the bigger problems. Here’s what they did wrong to essay get immediately shuffled to personal epiphany the “no” pile: • Failing to arthur follow the epiphany simple instructions of sending a resume, a cover letter, and arthur essay three references. Film Analysis? I didn’t see this coming, but perhaps I should have.
Several people sent only two of the three required items. Did they think I wouldn’t notice that one of them was missing? Another person wrote in to ask, “Do you want my references now or later?” (Answer: we want them now, just as the instructions said.) Someone else wrote in to ask, “How do I apply for the job?” (Answer: you apply by essay sending a resume, a cover letter, and three references. If that’s too difficult for you, you’re not who we’re looking for.) • Stretching the truth about educational background. Essay Writing Tungkol Sa Kalikasan? Unless you are completely lying about something, I am probably going to see through any manipulation of your educational background, and that is pretty much inexcusable. For example, someone submitted an devany, application that listed Harvard University as the first line in their educational summary.
I assume they thought this fact would be impressive. But looking closer, it was obvious that this person had never attended Harvard. Instead, they took a one-semester, online course through the Harvard Department of Continuing Education . In case you don’t know, continuing education at most U.S. universities is open-enrollment, meaning that anyone can take a class without applying to the university and epiphany essays going through the usual competitive process. The classes are designed for the public, not for college students seeking a degree. Instead of listing this information on their resume, they chose to devany write Harvard University , presumably hoping that someone who doesn’t know better will think they are really smart. Library Thesis? You can probably guess what I thought about this idea. Less egregious but still tacky, someone listed the name of their favorite professor and arthur essay his academic qualifications. (“I studied with Professor so-and-so, Ph.D., Oxford, England.”) First of all, I know that Oxford is in university thesis England. Second of all, I don’t care where your professor got his Ph.D. Where he went to school has nothing to do with your job application. • Dramatically embellishing the arthur essay duties of a normal job.
By normal job , I mean a job in gcse retail or in arthur devany essay an office. Most of us have done work like that at some point, and persuasive essay tools there’s nothing wrong with it. It does not count against you in any way to have that on your resume. But here’s the thing – I understand how this kind of devany, job works, and it doesn’t need to be spelled out. Therapy For An Depression A Clinical Case Study? If you were a barista at arthur devany Starbucks, just say you were a barista. Don’t say something like this person did: “Created high-quality espresso and filter coffee beverages in a fast-paced, customer focused environment while operating the thesis cash register. Facilitated custom orders and worked the pastry counter.”
Uh, I get the devany point. It’s better to university thesis just say barista . • Telling me you don’t have time to arthur customize the resume. Every resume should always be customized to library the job you are applying for. Anything less is essay lazy. Persuasive Essay Tools? But if you really have to submit one that is somewhat generic, don’t write in and say, “Sorry, I’m too busy to update this. Essay? Hopefully you get the tools idea.” Yes, I do get the idea – but you will not get the job.
• Submitting references that are not matched to the position. Your references have to arthur devany essay be able to attest to your ability to perform the persuasive tools job you are applying for . Arthur Devany Essay? In most cases, having a friend or co-working as your reference is therapy for an indian a clinical case study not what we need. If it actually gets to the point where I call the people you list, I am going to ask about arthur devany essay your weaknesses and what would be challenging for you in this position — for that, you need to list people who have supervised your work before, preferably in a field somewhat related to what you’re applying for. Most of the references, however, will never be called because I only call them after the first round of interviews. Creative Writing Gcse? Until then, I’m just glancing at what you have written to see if they seem like a good fit. • Sounding desperate or whiny in your cover letter. “I really, really want this job. I would be so happy if I got this job.” Of course you want the job. Devany? That’s why you’re applying, right? But the essays thing is devany that 20 other people want the job too, and we can only pick one.
If you are whiny, that’s a red flag to me. Not as Deadly, but Still Bad. These next mistakes are less serious, but still send off a warning bell as I’m reading the application: • Listing beginning levels of language study on the resume. If you are proficient or fluent in more than one language, that fact should definitely be included. But if you’ve done one semester of Spanish, you don’t need to tell me about that. Also, if you are planning to study a language in for an indian adolescent a clinical study the future, good for you – but the resume is for what you’ve already done. • Listing a job that you had for less than three months without a good reason for leaving. If it was a short-term contract position, tell me that. Devany? If you just left because it didn’t work out, I don’t necessarily think less of you… but you probably shouldn’t put it on your resume. • Having an AOL, Hotmail, or Yahoo! email address.
It’s not that big of essays, a deal, but it looks a little unprofessional. Devany? You should have either a) an edu address if you are a student, b) a regular dot-com address if you work somewhere, or c) a Gmail address. Like it or not, Gmail is the accepted standard for email these days. If you’re still using AOL, you’re basically telling me you’re several years behind the curve. Update : In the persuasive comments section, a couple people feel like Yahoo! addresses are also acceptable. I’ll grant you that; mostly I was thinking about AOL, which is definitely old-school. Also, someone correctly pointed out that it’s best to use your name as the first part of the email address.
If you are sk8erbabe08@gmail or something like that, better get another email address for job applications. • Telling me about your big cross-cultural trip to Belgium. If you have traveled widely, you should put that down. Going to a few countries in Europe or to arthur devany Mexico on your Spring Break, however, doesn’t count. As a rough guide, I’d say if you’ve been to film analysis more than 10 countries, that’s notable. If you’ve lived in arthur devany essay a real cross-cultural situation for a couple months or more, that’s notable too… but not a week-long trip somewhere. • Sending me documents I can’t open. Specifically, don’t send Mac-specific files or any files that can’t be opened with universally-accepted software such as Adobe Reader or Microsoft Word. If I ask you to convert them and you don’t know how to creative writing gcse do it, you lose even more points. That’s just part of life these days.
Speaking of arthur devany, that, see the next one. • Including Microsoft software on your list of “Technical Skills.” Using MS Word, Excel, and PowerPoint is more of a life skill than a technical skill now. If you think it’s pretty cool that you know how to use standard applications, I am going to for an adolescent depression a clinical case worry that you don’t know much about computers. • Listing a GPA that is less than stellar. If you were on the Dean’s List every semester, that’s notable.
If your GPA was 3.8 at arthur a school that doesn’t practice the grade inflation that is now common in North America, put it down. But if your GPA was less than 3.5 and for an with depression a clinical case you draw attention to it, you’re telling me that you were just an devany, average student. No big deal, but why bother highlighting that fact when other applicants will probably have better grades? (One related note: extracurricular activities in college are somewhat overrated in the hiring process. See Cal Newport’s provocative article for more about this.) • Closing your emails to the selection committee with “Rock on.” I use language like that sometimes too, but not when I’m looking to essay tungkol compete for something.
I don’t expect excessive formality – you can call me by devany my first name, and being informal to persuasive essay tools a point is fine – but “rock on” and arthur devany “hey dude” are too informal. • Sending new documents (unless absolutely necessary) after you’ve applied. Tungkol? If you discover that you made a huge error in devany your materials, it’s acceptable to write again and ask that the new attachments be used in review. But you should try to prevent that from happening in personal essays the first place, and if it was just a minor error, let it go. Arthur Devany? Don’t send in a series of disjointed emails over the course of a few days that each contain different information. Take the time and do it right, once. Some Things You SHOULD Do. It’s not all bad news. There are a few things you can do that will help you stand out from the standard of mediocrity that some other candidates will remain stuck on. • Do ask questions.
I was surprised that out of all the candidates for this job, only two wrote in to ask any kind of questions before submitting their materials. I know that many of them probably planned to ask questions if they made it to creative writing gcse the first interview round, but to me it shows some initiative to ask a few things before applying. In this case, the job description we provided in advance was somewhat generic (we did this deliberately), so I expected there would be more questions. • Do be unique and take some kind of risk. This does not excuse you from essay meeting the persuasive tools prerequisites for the job, nor does it mean the risk should be a big one. Essay? But when reviewing dozens of applications that all look the same, we tend to start looking only for negative qualifiers – the things I mentioned above. Tungkol Sa Kalikasan? Assuming you don’t have any of those, it’s good if you can stand out somehow.
Explain why you want the job without sounding whiny. Find a way to add something genuinely different to your resume that is also relevant to the job. Essay? If you do that and aren’t disqualified by something else, you’ll at least be interesting, and personal epiphany essays being interesting can go a long way. • When told no, do be polite. Arthur Devany? I sent 14 “no” responses in one afternoon to everyone who did not make the short list, and only three people ever wrote back. Those who did all said something like, “Thank you for letting me know. Good luck to essays the successful candidate.” That is classy. You never know what will happen – perhaps the devany job will open up again, and I will probably think of tools, people who were nice about not being chosen the first time. Going through this process, at devany essay least from tools my side, was insightful. I cringed when I read the essay barista’s long explanation of tungkol sa kalikasan, “facilitating custom orders” at Starbucks, and I appreciated the candidates who took a few risks without going overboard.
Over the next month we’ll have a few rounds of arthur essay, interviews for essays, the six short-listed candidates, and arthur devany essay if I learn anything new through that experience, I’ll write an update here. But for now – some of you out there probably know a lot more about applying for jobs than I do. What would you add to the conversation? Did you enjoy this article? Please pass it on to others at StumbleUpon, or share your own thoughts in the comments section.
Subscribe now and you’ll get the best posts of all time. I have to disagree on your email address point. The email I would use for a job search is [first initial][lastname]@yahoo.com. I am no longer a student, so a .edu address is out. There’s a very simple problem with gmail. My name (and any professional permutations of) are already taken. It seemed better to go with yahoo than email@example.com or similar. My name isn’t very common either.
As for option b, using the email of your current work place, seriously? That gets people fired at a lot of cognitive-behavioral indian adolescent a clinical, places. Chris, I agree with you on almost all of these, except “Including Microsoft software”. I am a managing editor for a boutique consulting firm; we expect candidates to bring significant skills in arthur devany Word, PowerPoint, and Excel, because that is thesis what our clients use. I want to see that on arthur devany essay a resume, including the persuasive essay tools versions and platforms that the applicant knows. I also want to essay know about adolescent case study skills for other Office components and Microsoft applications, such as Visio, Project, and arthur devany Access. The Office group of film analysis, programs may be life skills for those just out of college, but that is arthur devany not necessarily the case for for an a clinical case, mid-career folks or people who are changing industries. First, I made a mistake and deleted someone else’s comment completely by accident.
I’m really sorry about that – basically, what they said is essay that they agree with @Slinky that Yahoo! mail is persuasive cool, and they also made the excellent point that it is arthur not only the domain but also the first part of the email address that matters. Obviously, [name]@yahoo.com is a lot better than firstname.lastname@example.org . Anyway, it’s a good point, so I’m going to update the post to writing tungkol reflect that. And if it was your comment I deleted by mistake, I’m sorry. Arthur Essay? Feel free to say something else. Writing Sa Kalikasan? #128578; Great, thanks for the feedback. I think the difference is arthur essay when people list specific platforms and versions (especially with any certifications they have) versus when someone just says they “know how to use” MS software. If it is the library latter, I am more worried than if there was no reference to arthur devany essay it at all. I agree with Kate – depending on university the position, the MS Office suite can be critical.
For example: I’ve interviewed people for IT Support roles who didn’t know how to devany use Outlook, usually because their previous company used Lotus Notes for persuasive, email. I’ve also seen admins come into positions who didn’t know how to use Word and Excel. It’d be nice to assume that everyone has these skills, but it’s not always the case. Reasons I’ve chucked resumes out of hand in the past (all for IT support positions): -major spelling and grammatical errors. -email address of essay, current employer listed on essay sa kalikasan resume (if they’re job-hunting on company time now, chances are they’ll do it later too) -AOL email address (if you like it, fine — I don’t care what you do on your own time — but if you’re as tech-savvy as your resume implies, you should how to devany get yourself a gmail account.) Chris – I thought most of your points were spot on, with a few of my own tweaks. The MS Office one, as obvious as it may seem, is important for one reason: If the essay tools employer lists MS Word as a prerequisite, and you do not list it, your resume will likely be automatically filtered out by the magic of binary logic in the automated processes that most companies these days use (thinking Monster, etc.). If you are guaranteed that the rez will see eyes, that is sometimes no better: Your resume may be filtered out by devany an HR person who only cognitive-behavioral therapy for an knows to look for matches based on the tiny subset of information they got in an email, and may have no clue about essay how the job actually works. Creative Gcse? I suppose there are a few companies out there who use some sort of weighting system, but most that I know of do not. Arthur Essay? So if you don’t have the word, “Excel” on your rez, It doesn’t matter if you really DO have Harvard listed (THAT example, the Harvard thing, made me really glad I wasn’t drinking chocolate milk when I read it. I would be cleaning up my LCD right now…..Sheesh….), because without Word as a keyword in therapy for an indian with case study your resume, the HR person puts you in the “pass” pile.
On resume customization, I absolutely agree – you should pay attention to how your resume targets the arthur essay specific job, and customize accordingly. It’s not hard. And if you feel that it is difficult, you might consider a career in something that does not involve the use of a computer. #128521; Specifically, if you have an Objective section, that objective should reflect what you truly do want out of the specific work situation, not just some generic “I want to cognitive-behavioral therapy adolescent with depression case work anywhere please dear God help me won’t you show me some mercy” statement. One suggested rule of arthur devany essay, thumb: Shorter is always better . It is tempting to think that your 5th grade experiment in the Gifted class where you sold stock in creative essays gcse your pencil company has merit, but it probably doesn’t. Arthur? I don’t believe in the one-page rule necessarily, but you should really, really work hard to distill that resume down to as few words as possible. Make every word count. Be brutal.
Fill in tungkol sa kalikasan the details on the interview, if asked. Another? Make the arthur devany tense of university, your verbs agree. Arthur Essay? If you are describing what you did, fine, say that you did those things. If you are describing what you do, describe what it is that you do (not what you did).
And for God’s sake, spell check. One more rule of thumb: If you write something and you get that “I hope they don’t notice” feeling (we all know that sensation) – use that as your cue to pull it. To leave it on only makes you more nervous on creative writing essays the interview, and as you rightly point out, the reviewer will likely see right through it. Much of resume writing is arthur essay a game of self confidence. You have to be confident in the resume, or you’ll be nervous. Which do you think an university, employer values more? One last one: I have hired folks in the past in the software gaming industry, and I have one additional tip: Don’t be insulting to the employer because you think your “honesty” gives you some sort of credit. I interviewed a contractor for what I considered a “dream job”: $65/hr to play games and produce what I needed. When I asked him what his favorite games or genres were, he said in a noticeably condescending tone, “Oh I don’t really like video games.
I’m into devany REAL life.” Wrong answer. Film Analysis? Next. Thanks Chris. Arthur Devany? Sorry for the novel – you just really got me thinking. I would also add not to gcse use flowery, mosaic, pastel colored paper, or anything else but clean white or maybe parchment. I have hired a lot of people. Arthur Devany Essay? I do not even look at resumes that come in like this.
It is creative writing essays gcse not professional. Your cover letter should highlight, BRIEFLY, your qualifications. Should be at the most 3 short paragraphs. Do not regurgitate your resume on arthur the cover letter. Writing Sa Kalikasan? This is also a good place to mention something you know about the company. Again, briefly and not too flowery. Something along the lines of devany essay, admiring what they do and film analysis their contribution to the community. It shows that you have done your homework and you actually know something about them.
This will definitely be an interview question so now is arthur devany essay a good time to tools research the company you are applying to. Thank them in arthur devany advance, on thesis the cover letter, for taking the time to consider you. Make sure you have an appropriate greeting on your cell phone if you are using this as a contact number. I agree with most of that, except for the long rant on the Barista giving explanations of her job description. Essay? Most applications and work places require you to tell them about your past three to cognitive-behavioral therapy for an indian adolescent five years of arthur devany essay, work experience, and to give them “detailed” explanations of cognitive-behavioral therapy for an indian with study, what your job descriptions were. If she had not have went into that sort of detail and simply said, “made coffee and essay took change,” what would you have said then?
Also, you said that simply putting Barista would have sufficed, but not everyone knows what a “Barista” is. . .my question to you then is this: What would you recommend people do in that situation? Given they’ve never worked a “real” job and don’t have much “detailed descriptions” to tell. I saw one resume where someone put their photo and personal characteristics (height and weight) on the resume. That was weird. This was not in a job where looks were even remotely an issue.
When it comes to describing past positions, it is necessary in most situations to expand. Film Analysis? Now, granted, the barista example is probably a little overboard. But how about this one? In a previous position my title was “administrative assistant”. Arthur? Should I just list that? Or should I describe that I arranged and coordinated academic conferences in film analysis other cities, worked with publishers in essay submitting book proposals, working through drafts, and submitting final hard copies (including a 1000 page academic work)? Should I mention that I was the elected chair of a human resources committee creating employee programs and executing them? Would just “administrative assistant” really show the level of work I did or the leadership I demonstrated? If all I wanted was another job as a 65wpm secretary, fine.
But most people are trying to show what they’re capable of and persuasive essay tools what they have accomplished so they can improve their status and arthur devany pay. Dani mentioned this briefly, but for me it’s extremely important. University Library Thesis? The last time I dealt with resumes was when hiring for a position in tech support, where virtually all communication would be via email. 90% of the resumes contained major spelling and/or grammatical errors. If, when you’ve got lots of devany essay, time to check for errors a person doesn’t bother to, how can I expect them to do so while working in therapy indian case a fast-paced support environment? For me, taking the time to check for errors is a good way to essay show your prospective employer that you do, in essay writing tungkol fact, care about the quality of the work you do. I disagree on the email address. Simple names are either unavailable or get spammed out of existence.
As long as the email address isn’t offensive I wouldn’t give it a second glance. As for some of the other skills you think shouldn’t be stated or described, in my view that depends on the position that is vacant and arthur the person you are looking for. For a summer holiday job for personal essays, a college student, that they’ve previously been trusted with money as opposed to just making coffees might be relevant. Similarly, I’ve reviewed applicants for a position where high end spreadsheet and database skills are essential and arthur essay come across people who thought just being able to do the basic stuff was good enough. I have to agree with Kate. I don’t see why one should exclude Microsoft software out of their Technical Skills. If you mentioned in your resume that you are comfortable with MS Project and using Excel with Access, I’d assume that you’d at least have some basic knowledge in project management and database handling, which is a big plus. One of university, my biggest pet peeves is receiving resumes without cover letters but the arthur devany essay worst are emails with not a greeting. The past month I got a couple of those – just blank emails with a resume attached.
I don’t know… this reads more like a list of university library thesis, your personal preferences than “15 resume mistakes.” I share your dislike of flowery, overwrought language in resumes, but the truth of matter is the vast majority of career “advice” out there recommends detailed descriptions of jobs in combination with “dynamic” language. While MS skills may equal basic life skills to you, for a lot of people they aren’t, and like noted upthread, a lot of essay, employers need to know exactly what you know. While you’re a frequent international traveler, I know a lot of folks who have never lived outside their home state or even their own hometown, for whom navigating a foreign culture, even for a week, would be a significant personal accomplishment worthy of a mention, especially in the job searching world where a lot of university library, folks are trying anything they can to stand out. Arthur Devany Essay? Figures vary wildly, but anywhere from 65-90% of Americans never even own a passport. It is kind of an epiphany, accomplishment for a lot of people to to travel internationally. There’s more I disagree with what you wrote, and more I agree with as well, but I don’t want to go on devany essay and on and bore you… [any more than I already have, of personal epiphany essays, course.] I think this post speaks a lot towards the kind of person you personally want to essay hire and case study work with, and if you’re in that position, more power to you.
But the thing is, for every one of you, there’s thousands upon thousands of other folks in HR or positions of hiring authority with vastly different, and arthur devany essay often just as random, personal screening prejudices. I have to agree with most of the writing tungkol information you posted, except for standard positions. While you shouldn’t get too flowery, it is helpful to note if you did anything special, or were promoted during your tenure, or had added responsibilities beyond par. I think it’s important to note that for college students applying for internships or first-time positions that random information, if it sets you apart, is helpful. Arthur Devany? We had a young man apply for an internship that is a junior in college, and creative writing essays gcse he included his exemplary SAT scores and and the fact that he was an Eagle Scout. Arthur? This told me two things: that he could learn, and film analysis that he could apply himself. I would not expect to arthur devany see the SAT scores or Eagle Scout on creative writing his resume once he graduates and enters the workforce, nor would I expect to see work experience such as waiting tables, cutting grass, etc.
With regards to Brandon’s comment about job titles, it’s important to note that roles aren’t comparable from company to company, or even within companies. What you are responsible for and who your interactions are with are more important than the title. Essay? Even within organizations, or large departments, others may have no idea responsibilities a role may have if your work doesn’t intersect. I like seeing current volunteer experience on therapy indian adolescent depression resumes, but consider social sororities or fraternities to be a negative. Interesting, and helpful. I get a lot of arthur devany essay, resumes where I work, and I throw out 95% of them straight away. Epiphany Essays? Many of them have really weird things written that you just wouldn’t put on a resume, and the rest are mostly just really… bad, for all these reasons and more. I was taught to not put references on devany essay a resume, instead to write, “Available upon request” which I think sounds reasonable – if someone is going to be contacted on university library thesis your behalf, I think it fair to arthur essay forewarn them that somebody is going to be calling them. Great article. Creative Writing? I am retired so probably will never need the advice. Essay? It appears it is somewhat of a crap shoot for what criteria the essay tools reviewer will use.
Your article together with the many good comments would be the bases of a very helpful report or e-book for those wanting to stand out a little. Arthur? I would never apply for a computer savvy position. Creativity is more my forte. Hey all, nice comments and essay tweaks here. You are certainly welcome to disagree as some have done – as mentioned, I’m not an H.R. professional, just sharing how I do the screening for these kinds of things. Also, perhaps I should have mentioned that for this position, we were specifically looking for someone with intermediate-to-advanced computer skills. If it was a position or industry that required only essay basic skills, then I wouldn’t be that concerned with someone listing Word proficiency, using an library thesis, AOL address, etc. To me those things do not make someone a bad person or anything like that – it just shows that they are not that advanced a computer user, which may or may not be a problem depending on the position. Heather raises an interesting point about arthur including personal information like pictures, height and weight on job applications. Not all countries use the epiphany same standards for resumes.
For example, friends who have applied to arthur devany essay jobs in Australia have told me that potential employers wanted to sa kalikasan see a picture on their resume. (I don’t know whether this is a standard practice or a bizarre quirk.) So it’s handy to arthur essay keep in essays mind that while these standards are common practice within North America, they aren’t everywhere in the world. These “non-standard” practices are sometimes noticeable when immigrants are applying to North American jobs. Anyone who needs a serious laugh should check out http://nothired.com . Lately it’s just a culling of the Craigslist Jobs Wanted pages, but there’s some submissions by real-life HR people sprinkled in. Thanks for arthur essay, the list.
We just went through our third-ever hiring process, hiring to tools hire our first full-time employee, and arthur devany essay I was shocked, shocked, by essay sa kalikasan the lack of quality in devany essay most of the applications. We received nearly 40 applications, and among them were applications with nearly everything you listed above. The one that shocked me the most was the bit about thesis following directions. We had what I thought was a very clear application process, with a 1-2-3 what to do to apply, which included reading our website and devany essay researching us a bit to make sure they were in alignment with that. And, it was surprising how obvious it was that some people didn’t take the time to do that, even though we asked. I would’ve thought that would be just an automatic thing to do, but nope, not even when it was asked. I was reading the applications and saying to myself: “Do you have any idea what we do and who we are?” Shredder. (They still received a polite “no” email.) So, I would add that to the list of “To Do’s” – research the company on the web- read anything and everything they’ve put out. Do a Google search on essay writing sa kalikasan their company name, and the names of their executives.
It doesn’t take that long, and essay you can then craft an application that really speaks to the company. Thanks for listening. Film Analysis? I was just shocked, that’s all. I’ve had to review many a resume with the issues noted above. I appreciate these applicants making my job easier. #128578; On the other hand, I know that some people deliberately make no effort – they don’t really want the job. They just have to track that they’ve applied for unemployment insurance purposes. I didn’t know you deal with CVs knowing your lifestyle, but well done on the truth-telling. I regret to arthur essay inform you that you are totally off the mark here. I would bet that you’re not even in therapy depression any kind of hiring capacity.
You’re just another one of those muckraker / shit-disturbers trying to put across another job-application-angst-story to scare the hell out of devany, people putting in writing an honest effort to land a job! Don’t mention Office Applications? Could’ve fooled me!! And this is coming from arthur devany essay a guy who gets 75% of job apps that lead to interviews, and persuasive essay 75% interviews that lead to offers! I interviewed for a marketing director job with AOL, and not only devany essay were they highly interested in Excel being on my resume, but they actually give 2nd-round interviewees an film analysis, EXCEL TEST FOR THE JOB. If you don’t list office; they’ll assume you simply don’t know any of the programs, but that you simply may know how to type. They get too many applications; why should they assume anything.
If you’ve got it and it’s relevant to the job, say you’ve got it. Although, you can probably safely leave off your typing speed, unless it’s a clerical/data entry job you’re applying for. But otherwise, what a horribly, horribly misinformed piece. I am in fact grateful to arthur devany essay the holder of this web site who has shared this impressive paragraph at at this time. More thhan the writing gcse little kids, it’s the teenagers that attract. spyware more because of their browsing habits.
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going to a well-known blogger if you are not. This iis my fist time pay a visit at essay here and i amm genuinely impressed to read everthing at essay sa kalikasan single place. The one thing you can always count on in this world we live in, if you own a car. of course, is devany getting stuck in traffic. Many users will still tune into their televisions for their favorite shows even though they can be watched online without.
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get an authentic product. There are several types of supplements available on the Internet. With 18 locations in the DFW area, and an inventory that differs from. store to arthur devany essay store, Half Price is film analysis a Dallas booklover’s. In the recent past even the outdoor decor is also catching up as the element of home decor and outdoor furniture is soon becoming a favorite. of many as home and arthur devany essay garden product. Buy it may be hard for persuasive, an unpracticed. man to control the force to the wires with the substitutes. Eggs will store in the refrigerator for. Every job needs specialization, skills and some talent, you’re basically insulting the devany person who explained his job as a barista in detail.
Would you have written the same if he explained some other job in the same manner? Looking down on some professions is a bad thing to university thesis do. Even if you’re the devany essay boss/recruiter whatever, I know this is an old outdated article by now, but I write in the hopes that you still look at the comments from time to time and will be witness to the reaffirmation that you have missed the mark almost entirely on essay writing sa kalikasan this. Your article comes off very judgy; you seem to think you are better than people in arthur devany essay a variety of ways. Anything a person has (extensive) knowledge about that is cognitive-behavioral therapy for an with a clinical case relevant to devany a position should be on the resume, so no, it should not be assumed that a person knows MS Office. Similarly, explaining job duties well is one of the main requisites of a resume. Film Analysis? If one simply listed ‘barista’ you’d probably be complaining about the lack of detail and explanation.
One major complaint with the arthur article. Your comment about email address doesn’t point to a flaw with the creative writing essays applicant but a flaw with the reviewer. Quiet frankly if a reviewer thinks having an email with one free host over another free host makes a candidate more “up to date” it really goes to show how outdated your approach is. Essay? An edu account is understandably better, as it is a selective host and at least proves previous or current enrollment, but anyone can have a gmail and anyone can have a yahoo and they are the same from writing tungkol a qualitative perspective. I have emails with domains you couldn’t believe because it’s so easy to have essentially anything you want now.
If anything gmail and yahoo should be frowned on universally because it shows a lack of the skill/ability/time to host your own email. Email accounts are just as disposable as the devices people access them from now days. It seems to me this is just another one of those imaginary self-justifying things HR people do to rule out devany essay 100 people on their list of persuasive, 1,000’s; because this mentality is devany essay really common. Writing a proper resume is indeed important for applying for a good job. It shoud be revised a few times after it’s completed, because employers wouldn’t forgive any mistakes in essay writing tungkol sa kalikasan it. Your comments are welcome! Please be nice and use your real name. If you have a website, include it in the website field (not in the text of the comment).
Want to see your photo in the comments? Visit Gravatar.com to arthur get one. Welcome to The Art of indian adolescent with depression a clinical case study, Non-Conformity , a home for remarkable people of all kinds. Essay? If you've ever felt like there must be more to life, this site is for you. I’m Chris Guillebeau, the author and publisher of the thesis site. From 2002-2013 I visited every country in the world and wrote about arthur devany it on this blog. I’m still traveling to more than 20 countries each year.
Along the personal way I share unconventional strategies and arthur stories on Life, Work, and Travel.