2,061 research outputs found
Spinor Green's functions via spherical means on products of space forms
We explicitly compute the Green's function of the spinor Klein-Gordon
equation on the Riemannian and Lorentzian manifolds of the form , with each factor being a space of constant sectional curvature.
Our approach is based on an extension of the method of spherical means to the
case of spinor fields and on the use of Riesz distributions.Comment: 15 pages
Green's function for the Hodge Laplacian on some classes of Riemannian and Lorentzian symmetric spaces
We compute the Green's function for the Hodge Laplacian on the symmetric
spaces M\times\Sigma, where M is a simply connected n-dimensional Riemannian or
Lorentzian manifold of constant curvature and \Sigma is a simply connected
Riemannian surface of constant curvature. Our approach is based on a
generalization to the case of differential forms of the method of spherical
means and on the use of Riesz distributions on manifolds. The radial part of
the Green's function is governed by a fourth order analogue of the Heun
equation.Comment: 18 page
Corrigendum: License to Kill? Domestic Cats Affect a Wide Range of Native Fauna in a Highly Biodiverse Mediterranean Country
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A shashlik calorimeter with longitudinal segmentation for a linear collider
Two techniques for longitudinal segmentation of shashlik calorimeters are proposed. Beam tests have demonstrated the technical feasibility of longitudinally segmented shashlik calorimeters in which longitudinal sampling is performed by lateral vacuum photodiodes or by using two scintillator types with different decay times. Results concerning energy resolution and e/π separation are presente
Apolipoprotein E imbalance in the cerebrospinal fluid of Alzheimer's disease patients.
Objective: The purpose of this study was to examine the levels of cerebrospinal fluid (CSF) apolipoprotein E (apoE) species in Alzheimer's disease (AD) patients. Methods: We analyzed two CSF cohorts of AD and control individuals expressing different APOE genotypes. Moreover, CSF samples from the TgF344-AD rat model were included. Samples were run in native- and SDS-PAGE under reducing or non-reducing conditions (with or without β-mercaptoethanol). Immunoprecipitation combined with mass spectrometry or western blotting analyses served to assess the identity of apoE complexes. Results: In TgF344-AD rats expressing a unique apoE variant resembling human apoE4, a ~35-kDa apoE monomer was identified, increasing at 16.5 months compared with wild-types. In humans, apoE isoforms form disulfide-linked dimers in CSF, except apoE4, which lacks a cysteine residue. Thus, controls showed a decrease in the apoE dimer/monomer quotient in the APOE ε3/ε4 group compared with ε3/ε3 by native electrophoresis. A major contribution of dimers was found in APOE ε3/ε4 AD cases, and, unexpectedly, dimers were also found in ε4/ε4 AD cases. Under reducing conditions, two apoE monomeric glycoforms at 36 kDa and at 34 kDa were found in all human samples. In AD patients, the amount of the 34-kDa species increased, while the 36-kDa/34-kDa quotient was lower compared with controls. Interestingly, under reducing conditions, a ~100-kDa apoE complex, the identity of which was confirmed by mass spectrometry, also appeared in human AD individuals across all APOE genotypes, suggesting the occurrence of aberrantly resistant apoE aggregates. A second independent cohort of CSF samples validated these results. Conclusion: These results indicate that despite the increase in total apoE content the apoE protein is altered in AD CSF, suggesting that function may be compromised
To Eat and To Be : food as Differenciation Policy in Spanish America, 16th and 17th Centuries
ABSTRACT: This paper demonstrates that food served as a marker of social differentiation during the 16th and 17th centuries in the Spanish possessions in America, not only in economic terms but also in the sense that food was associated with the social stratum to which a person belonged. Each one was oblidged to eat foods associated with his or her "natural" stratum. This complex hierarchical model of society was based on European patterns coming from the Middle Ages, such as the Great Chain of Being and humoral theory. This model was reinforced in the early modern period, and it took on new characteristics in America, where it was used to differentiate Spaniards, Creoles, Mestizos and Indians.RESUMEN: Este artículo muestra cómo la alimentación servía como un elemento de diferenciación social durante los siglos XVI y XVII, en la América española, no solo como un factor económico, sino asociado a la calidad o estado al que pertenecieran las personas. En este sentido, a cada uno le correspondía comer aquello que era propio de su condición estamental. Este complejo modelo de jerarquización social estaba basado en principios europeos que venían desde la Edad Media, como la gran cadena del ser y la teoría humoral. En la edad moderna, el modelo se reforzó y en América tomó nuevas características, por la forma en que se buscó diferenciar entre españoles, criollos, mestizos e indios
The small angle tile calorimeter in the DELPHI experiment
The {\bf S}mall angle {\bf TI}le {\bf C}alorimeter ({\bf STIC}) provides calorimetric coverage in the very forward region of the DELPHI experiment at the CERN LEP collider. The structure of the calorimeters, built with a so-called ``shashlik'' technique, gives a perfectly hermetic calorimeter and still allows for the insertion of tracking detectors within the sampling structure to measure the direction of the showering particle. A charged-particle veto system, composed of two scintillator layers, makes it possible to trigger on single photon events and provides e- separat ion. Results are presented from the extensive studies of these detectors in the CERN testbeams prior to installation and of the detector performance at LEP
Energy Resolution Performance of the CMS Electromagnetic Calorimeter
The energy resolution performance of the CMS lead tungstate crystal electromagnetic calorimeter is presented. Measurements were made with an electron beam using a fully equipped supermodule of the calorimeter barrel. Results are given both for electrons incident on the centre of crystals and for electrons distributed uniformly over the calorimeter surface. The electron energy is reconstructed in matrices of 3 times 3 or 5 times 5 crystals centred on the crystal containing the maximum energy. Corrections for variations in the shower containment are applied in the case of uniform incidence. The resolution measured is consistent with the design goals
b-tagging in DELPHI at LEP
Abstract: The standard method used for tagging b-hadrons in the DELPHI experiment at the CERN LEP Collider is discussed in detail. The main ingredient of b-tagging is the impact parameters of tracks, which relies mostly on the vertex detector. Additional information, such as the mass of particles associated to a secondary vertex, significantly improves the selection efficiency and the background suppression. The paper describes various discriminating variables used for the tagging and the procedure of their combination. In addition, applications of b-tagging to some physics analyses, which depend crucially on the performance and reliability of b-tagging, are described briefly
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