950 resultados para pot experiment
Resumo:
In this work we present the J/psi measurement in p+p collisions within the STAR collaboration Quarkonium program. This measurements aim to be the baseline measurement of a more comprehensive systematic study of quarkonium states production in order to understand their in medium modification. Here we report the total cross section and rho(T) distribution, and find them to be consistent with pQCD CEM predictions as well as to previous measurements at the same center-of-mass energy.
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In recent years, PHENIX has studied many important observables related to heavy-flavor physics through their leptonic decay measurements including the invariant yield of electrons from nonphotonic sources, and prompt single muons, both of which are dominated by D and B mesons. Charm and beauty cross-sections were measured and compared through single lepton, and lepton-hadron correlations in p+p collisions at root s = 200 GeV. Observables for quarkonia production such as invariant yield and polarization were also measured in p+p collisions. In Au+Au collisions, preliminary results for the R(AA) for single electrons and a 90% CL upper limit for the suppression of s were produced. And in d+Au collisions, a preliminary R(CP) study for J/psi production in different centrality ranges was extracted.
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We report the J/psi -> e(+)e(-) and the psi` -> e(+)e(-) production cross sections in the PHENIX experiment at RHIC. The first measurements of the production cross sections of the psi` and the psi` over the J/psi, will contribute to the clarification of the theoretical understanding of the J/psi meson production. The inclusive J/psi polarization through the same decay channel is also presented, showing a trend of slightly longitudinal polarization for p(T) <5 GeV/c.
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We observe experimentally a deviation of the radius of a Bose-Einstein condensate from the standard Thomas-Fermi prediction, after free expansion, as a function of temperature. A modified Hartree-Fock model is used to explain the observations, mainly based on the influence of the thermal cloud on the condensate cloud.
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The reconstruction of Extensive Air Showers (EAS) observed by particle detectors at the ground is based on the characteristics of observables like the lateral particle density and the arrival times. The lateral densities, inferred for different EAS components from detector data, are usually parameterised by applying various lateral distribution functions (LDFs). The LDFs are used in turn for evaluating quantities like the total number of particles or the density at particular radial distances. Typical expressions for LDFs anticipate azimuthal symmetry of the density around the shower axis. The deviations of the lateral particle density from this assumption arising from various reasons are smoothed out in the case of compact arrays like KASCADE, but not in the case of arrays like Grande, which only sample a smaller part of the azimuthal variation. KASCADE-Grande, an extension of the former KASCADE experiment, is a multi-component Extensive Air Shower (EAS) experiment located at the Karlsruhe Institute of Technology (Campus North), Germany. The lateral distributions of charged particles are deduced from the basic information provided by the Grande scintillators - the energy deposits - first in the observation plane, then in the intrinsic shower plane. In all steps azimuthal dependences should be taken into account. As the energy deposit in the scintillators is dependent on the angles of incidence of the particles, azimuthal dependences are already involved in the first step: the conversion from the energy deposits to the charged particle density. This is done by using the Lateral Energy Correction Function (LECF) that evaluates the mean energy deposited by a charged particle taking into account the contribution of other particles (e.g. photons) to the energy deposit. By using a very fast procedure for the evaluation of the energy deposited by various particles we prepared realistic LECFs depending on the angle of incidence of the shower and on the radial and azimuthal coordinates of the location of the detector. Mapping the lateral density from the observation plane onto the intrinsic shower plane does not remove the azimuthal dependences arising from geometric and attenuation effects, in particular for inclined showers. Realistic procedures for applying correction factors are developed. Specific examples of the bias due to neglecting the azimuthal asymmetries in the conversion from the energy deposit in the Grande detectors to the lateral density of charged particles in the intrinsic shower plane are given. (C) 2011 Elsevier B.V. All rights reserved.
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The properties of galactic cosmic rays are investigated with the KASCADE-Grande experiment in the energy range between 10(14) and 10(18) eV. Recent results are discussed. They concern mainly the all-particle energy spectrum and the elemental composition of cosmic rays. (C) 2010 Elsevier B.V. All rights reserved.
Resumo:
The substitution of petroleum-based fuels with those from renewable sources has gained momentum worldwide. A UV-vis experiment for the quantitative analysis of biofuels (bioethanol or biodiesel) in (petroleum-based) diesel oil has been developed. Before the experiment, students were given a quiz on biofuels, and then they were asked to suggest a suitable UV-vis experiment for the quantification of biofuels in diesel oil. After discussing the results of the quiz, the experiment was conducted. This included the determination of lambda(max) of the medium-dependent, that is, solvatochromic, visible absorption band of the probe 2,6-bis[4-(tert-butyl)phenyl]-4-{2,4,6-tris[4-(tert-butyl)phenyl]pyridinium-1-yl}phenolate as a function of fuel composition. The students appreciated that the subject was linked to a daily situation and that they were asked to suggest the experiment. This experiment served to introduce the phenomena of solvation and solvatochromism.
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Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)
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A simple and efficient procedure for the synthesis of beta-seleno and beta-thio amides via the ring-opening reaction of chiral 2-oxazolines in the presence of indium metal has been developed. Features of this method include the following: (i) easily and accessible starting materials; (ii) indium metal is more stable and less expensive then its respective salts; (iii) useful to excellent yields of beta-chalcogen amides derivatives. (C) 2008 Elsevier B. V. All rights reserved.
Resumo:
A natural experiment is used to identify the causal relationship between employment protection legislation and fi rm growth. The natural experiment occurred in Sweden in 2001, when an exemption made it possible for fi rms with less than eleven employees to exclude two workers from the last-in-fi rst-out principle when dismissing personnel. The estimated average treatment effect of the reform show that the number of employees increased with 0.135 percent in fi rms with 5-9 employees relative to fi rms with 10-15 employees, which corresponds to over 5,000 additional jobs per year created by the reform. Firms with ten employees, just below the size threshold, became 3.4 percent less likely to increase their workforce to a level surpassing the threshold, indicating that the last-in- first-out rule prevented these firms from growing. Thus, employment protection legislation seems to act as a growth barrier for small fi rms.
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In a natural experiment, this paper studies the impact of an informal sanctioning mechanism on individuals’ voluntary contribution to a public good. Cross-country skiers’ actual cash contributions in two ski resorts, one with and one without an informal sanctioning system, are used. I find the contributing share to be higher in the informal sanctioning system (79 percent) than in the non-sanctioning system (36 percent). Previous studies in one-shot public good situations have found an increasing conditional contribution (CC) function, i.e. the relationship between expected average contributions of other group members and the individual’s own contribution. In contrast, the present results suggest that the CC-function in the non-sanctioning system is non-increasing at high perceived levels of others’ contribution. This relationship deserves further testing in lab.
Resumo:
Young people now spend a longer and longer period of their lives at school then ever before. Not always because that they want to, but because society has nothing else to offer. The situation in many schools may also, in different aspects, be seen as highly problematic. Andersson (2001) has, for example, found in a large longitudinal study - The Life Project – that schools seem to be adapted to the needs of only a minority of the students - around 30%. On the other hand school is badly adjusted to the requirements of another 30 %. This group of students often find school meaningless, uninteresting and boring. For these students school is mostly a waste of time. In such circumstances, it seems natural that society has a responsibility to offer young people a meaningful time at school, both here and now and to prepare them for a future live as adults, not only as a part of the work force.As a part of departure I briefly describe the model that Antonovsky has developed and try to use it in a school context instead. I have here, of course, no possibility to make a deeper analysis of a complex problem such as this.In Antonovsky’s spirit, using a salutogenic perspective, instead of asking ourselves why do pupils fail or perhaps also not like being at school we have to ask, instead: What it is that makes pupils successful? From this background the purpose of this paper is to discuss some aspects of how pupils may use different strategies to handle their school situation in a proper way.
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Very large scale computations are now becoming routinely used as a methodology to undertake scientific research. In this context, `provenance systems' are regarded as the equivalent of the scientist's logbook for in silico experimentation: provenance captures the documentation of the process that led to some result. Using a protein compressibility analysis application, we derive a set of generic use cases for a provenance system. In order to support these, we address the following fundamental questions: what is provenance? how to record it? what is the performance impact for grid execution? what is the performance of reasoning? In doing so, we define a technologyindependent notion of provenance that captures interactions between components, internal component information and grouping of interactions, so as to allow us to analyse and reason about the execution of scientific processes. In order to support persistent provenance in heterogeneous applications, we introduce a separate provenance store, in which provenance documentation can be stored, archived and queried independently of the technology used to run the application. Through a series of practical tests, we evaluate the performance impact of such a provenance system. In summary, we demonstrate that provenance recording overhead of our prototype system remains under 10% of execution time, and we show that the recorded information successfully supports our use cases in a performant manner.