Applicability of Monte Carlo Glauber models to relativistic heavy ion collision data

The accuracy of Monte Carlo Glauber model descriptions of minimum-bias multiplicity frequency distributions is evaluated using data from the Relativistic Heavy Ion Collider (RHIC) within the context of a sensitive, power-law representation introduced previously by Trainor and Prindle (TP). Uncertainties in the Glauber model input and in the mid-rapidity multiplicity frequency distribution data are reviewed and estimated using the TP centrality methodology. The resulting errors in model-dependent geometrical quantities used to characterize heavy ion collisions ({\em i.e.} impact parameter, number of nucleon participants $N_{part}$, number of binary interactions $N_{bin}$, and average number of binary collisions per incident participant nucleon $\nu$) are presented for minimum-bias Au-Au collisions at $\sqrt{s_{NN}}$ = 20, 62, 130 and 200 GeV and Cu-Cu collisions at $\sqrt{s_{NN}}$ = 62 and 200 GeV. Considerable improvement in the accuracy of collision geometry quantities is obtained compared to previous Monte Carlo Glauber model studies, confirming the TP conclusions. The present analysis provides a comprehensive list of the sources of uncertainty and the resulting errors in the above geometrical collision quantities as functions of centrality. The capability of energy deposition data from trigger detectors to enable further improvements in the accuracy of collision geometry quantities is also discussed.Comment: 27 pages, 4 figures, 11 table

Dielectric Properties of the Quasi-Two-Dimensional Electron Liquid in Heterojunctions

A quasi-two-dimensional (Q2D) electron liquid (EL) is formed at the interface of a semiconductor heterojunction. For an accurate characterization of the Q2D EL, many-body effects need to be taken into account beyond the random phase approximation. In this theoretical work, the self-consistent static local-field correction known as STLS is applied for the analysis of the Q2D EL. The penetration of the charge distribution to the barrier-acting material is taken into consideration through a variational approach. The Coulomb from factor that describes the effective 2D interaction is rigorously treated. The longitudinal dielectric function and the plasmon dispersion of the Q2D EL are presented for a wide range of electron and ionized acceptor densities choosing GaAs/AlGaAs as the physical system. Analytical expressions fitted to our results are also supplied to enable a widespread use of these results.Comment: 39 pages (in LaTeX), including 8 PostScript figure

Fermi-Dirac and Bose-Einstein Functions of Negative Integer Order

We find simple explicit closed-form formulas for the Fermi-Dirac function F(-n)(z) and Bose-Einstein function B(-n)(z) for arbitrary n is an element of N. The obtained formulas involve the higher tangent numbers defined by Carlitz and Scoville. We present some examples and direct consequences of applying the main results

Interleucina-18 (IL-18) y otros parámetros inmunológicos como marcadores de gravedad en la pancreatitis aguda Interleukin 18 (IL-18) and other immunological parameters as markers of severity in acute pancreatitis

Objetivo: se trata de comparar prospectivamente el comportamiento durante la primera semana del ingreso de los niveles de interleucina-18 (IL-18), y otros parámetros inmunológicos entre pacientes con pancreatitis aguda con y sin criterios de gravedad, así como entre pacientes con y sin desarrollo ulterior de seudoquiste. Pacientes y métodos: se compararon en 36 pacientes con pancreatitis aguda los resultados de sTNF-RI, IL-1Ra, IL-6 e IL-18 los días 1, 2, 3 y 7 desde el ingreso entre pancretitis leve, grave y un grupo control (13 pacientes) con cólico biliar simple, así como entre pacientes con o sin seudoquiste. Resultados: al comparar pancreatitis leve con grave, IL-18 fue significativamente superior sólo el primer día en las pancreatitis graves y los otros parámetros a partir del segundo día de forma mantenida. También en pacientes que desarrollaron seudoquiste, IL-18 estuvo significativamente elevada el primer día. Conclusiones: IL-18 resultó el marcador más precoz de complicaciones y gravedad de la pancreatitis aguda a nivel sistémico y local (seudoquiste).Objective: our aim was to prospectively compare the behavior of interleukin 18 (IL-18) levels and other immunological parameters during the first week of hospitalization between acute pancreatitis patients with and without severity criteria, as well as between patients with and without late pseudocyst development. Patients and methods: in 36 patients with acute pancreatitis we compared sTNF-RI, IL-1Ra, IL-6, and IL-18 levels at days 1, 2, 3 and 7 after hospitalization between mild pancreatitis, severe pancreatitis, and a "control" group (13 patients) with uncomplicated biliary colic, as well as between patients with and without pseudocyst. Results: on comparing mild to severe pancreatitis, IL-18 was significantly higher only the first day in severe pancreatitis, while the other parameters were steadily higher after the second day. In patients developing pseudocyst, IL-18 was also noticeably higher the first day. Conclusions: IL-18 appears to be the earliest marker of complications and severity in acute pancreatitis at both the systemic and local level (pseudocyst)