Spatial Resolution of Double-Sided Silicon Microstrip Detectors for the PAMELA Apparatus

The PAMELA apparatus has been assembled and it is ready to be launched in a satellite mission to study mainly the antiparticle component of cosmic rays. In this paper the performances obtained for the silicon microstrip detectors used in the magnetic spectrometer are presented. This subdetector reconstructs the curvature of a charged particle in the magnetic field produced by a permanent magnet and consequently determines momentum and charge sign, thanks to a very good accuracy in the position measurements (better than 3 um in the bending coordinate). A complete simulation of the silicon microstrip detectors has been developed in order to investigate in great detail the sensor's characteristics. Simulated events have been then compared with data gathered from minimum ionizing particle (MIP) beams during the last years in order to tune free parameters of the simulation. Finally some either widely used or original position finding algorithms, designed for such kind of detectors, have been applied to events with different incidence angles. As a result of the analysis, a method of impact point reconstruction can be chosen, depending on both the particle's incidence angle and the cluster multiplicity, so as to maximize the capability of the spectrometer in antiparticle tagging.Comment: 28 pages, 18 figures, submitted to Nuclear Instruments and Methods in Physics Research

Extreme magnification of an individual star at redshift 1.5 by a galaxy-cluster lens

Galaxy-cluster gravitational lenses can magnify background galaxies by a total factor of up to ~50. Here we report an image of an individual star at redshift z = 1.49 (dubbed MACS J1149 Lensed Star 1) magnified by more than ×2,000. A separate image, detected briefly 0.26″ from Lensed Star 1, is probably a counterimage of the first star demagnified for multiple years by an object of ≳3 solar masses in the cluster. For reasonable assumptions about the lensing system, microlensing fluctuations in the stars’ light curves can yield evidence about the mass function of intracluster stars and compact objects, including binary fractions and specific stellar evolution and supernova models. Dark-matter subhaloes or massive compact objects may help to account for the two images’ long-term brightness ratio

Study on the temperature dependence of the bulk modulus of polyisoprene by molecular dynamics simulations

The temperature dependence of the bulk modulus of polyisoprene has been studied using molecular dynamics simulations. Virtual polyisoprenes have been submitted to volume contractions above and below the glass transition. Bulk modulus has been observed to be linearly dependent on temperature both above and below the glass transition respectively, and it dropped by a factor of about 2 while temperatures was risen above the glass transition. By monitoring the energy changes during volume contractions, it was observed that the bulk modulus arises mainly from the Van de Waals interactions. Nevertheless, the entropy contribution to the bulk modulus becomes significant above the glass transition. At a first order, the entropy part of the bulk modulus can be considered as independent on the temperature.Projet ANR jeunes chercheurs MELAC JC05_43403

Rostovtzeff at Dura-Europos

С 1928 по 1937 г. Йельский университет и французская Académie des Inscriptions et Belles Lettres вели систематические археологические раскопки на месте древнего города Дура-Эвропос. Основанная одним из полководцев Александра Македонского в естественно укрепленном месте, на западном берегу р. Евфрат, Эвропос была типичной военной колонией Селевкидов, в культуре которой смешались язык, культура и право греков с местной семитской традицией. Десять сезонов раскопок в Дуре, проведенных совместной экспедицией Йельского университета и французских исследователей, вскрыли разнообразное культурное и религиозное влияние различных групп населения, живших в городе и управлявших им. Эти важные археологические изыскания, возглавляемые, задуманные и вдохновляемые Михаилом Ивановичем Ростовцевым, перевернули представления специалистов об искусстве ранних христианских и еврейских поселений в римской Сирии и выявили изумляющее и ранее непризнававшееся сильное восточное влияние на искусство и культуру восточных римских провинций. В статье, во-первых, будут рассмотрены причины выбора Ростовцевым именно Дуры-Эвропос в качестве объекта археологических исследований Йельского университета, и, во-вторых, показано, каким образом в этих исследованиях отразился неизменный интерес М.И. Ростовцева к проблеме взаимодействия греко-римской цивилизации и Востока.Перевод статьи С.В. Дмитриева

The Dura-Europos Collection at Yale University

Статья посвящена описанию ряда археологических находок из Дура-Европос, хранящихся в коллекциях Йельского университета. Автор отмечает огромный научный потенциал этих артефактов.Публикация подготовлена при финансовой поддержке Российского фонда фундаментальных исследований (РФФИ). Проект № 02-06-87075. Прилагаются фотографии исследуемых артефактов (черно-белая вкладка). Перевод С.В. Кулланды

Integration of genetic and clinical risk factors improves prognostication in relapsed childhood B-cell precursor acute lymphoblastic leukemia

Somatic genetic abnormalities are initiators and drivers of disease and have proven clinical utility at initial diagnosis. However, the genetic landscape and its clinical utility at relapse are less well understood and have not been studied comprehensively. We analyzed cytogenetic data from 427 children with relapsed B-cell precursor ALL treated on the international trial, ALLR3. Also we screened 238 patients with amarrow relapse for selected copy number alterations (C