9,926 research outputs found
Time resolution below 100 ps for the SciTil detector of PANDA employing SiPM
The barrel time-of-flight (TOF) detector for the PANDA experiment at FAIR in
Darmstadt is planned as a scintillator tile hodoscope (SciTil) using 8000 small
scintillator tiles. It will provide fast event timing for a software trigger in
the otherwise trigger-less data acquisition scheme of PANDA, relative timing in
a multiple track event topology as well as additional particle identification
in the low momentum region. The goal is to achieve a time resolution of sigma ~
100 ps. We have conducted measurements using organic scintillators coupled to
Silicon Photomultipliers (SiPM). The results are encouraging such that we are
confident to reach the required time resolution.Comment: 10 pages, 7 figure
-approximation of the integrated density of states for Schr\"odinger operators with finite local complexity
We study spectral properties of Schr\"odinger operators on \RR^d. The
electromagnetic potential is assumed to be determined locally by a colouring of
the lattice points in \ZZ^d, with the property that frequencies of finite
patterns are well defined. We prove that the integrated density of states
(spectral distribution function) is approximated by its finite volume
analogues, i.e.the normalised eigenvalue counting functions. The convergence
holds in the space where is any finite energy interval and is arbitrary.Comment: 15 pages; v2 has minor fixe
On the Second Law of thermodynamics and the piston problem
The piston problem is investigated in the case where the length of the
cylinder is infinite (on both sides) and the ratio is a very small
parameter, where is the mass of one particle of the gaz and is the mass
of the piston. Introducing initial conditions such that the stochastic motion
of the piston remains in the average at the origin (no drift), it is shown that
the time evolution of the fluids, analytically derived from Liouville equation,
agrees with the Second Law of thermodynamics.
We thus have a non equilibrium microscopical model whose evolution can be
explicitly shown to obey the two laws of thermodynamics.Comment: 29 pages, 9 figures submitted to Journal of Statistical Physics
(2003
Broadband access in the EU: An assessment of future economic benefits
This paper evaluates the net benefits of the implementation of the broadband infrastructure deployment targets by 2020 as entailed by the Digital Agenda for Europe Initiative set forth by the European Commission. We estimate the returns from broadband infrastructure for the period 2005-2011, differentiating the impact of broadband by levels of adoption and speed while accounting for reverse causality and extensive heterogeneity. We find that in the base case scenario the overall benefits outweigh the costs by 32% for the entire European Union. We further extrapolate the returns by country under different scenarios of implementation. In most cases the benefits are substantially well above the costs. The findings lead to policy recommendations related to the role of public support for the generalized build out of broadband infrastructure
Inflammatory bowel disease-specific autoantibodies in HLA-B27-associated spondyloarthropathies: Increased prevalence of ASCA and pANCA
Aims: An association between inflammatory bowel disease (IBD) and spondyloarthropathies (SpA) has repeatedly been reported. The aim of the present study was to investigate whether serologic markers of IBD, e. g. antibodies against Saccharomyces cerevisiae (ASCA), antibodies against exocrine pancreas (PAB) and perinuclear antineutrophil cytoplasmic antibodies (pANCA) are present in HLA-B27-associated SpA. Methods: 87 patients with HLA-B27-positive SpA and 145 controls were tested for ASCA, PAB and pANCA employing ELISA or indirect immunofluorescence, respectively. Antibody-positive patients were interviewed regarding IBD-related symptoms using a standardized questionnaire. Results/Conclusion: When compared to the controls, ASCA IgA but not ASCA IgG levels were significantly increased in patients with SpA, in particular in ankylosing spondylitis (AS) and undifferentiated SpA (uSpA). pANCA were found in increased frequency in patients with SpA whereas PAB were not detected. The existence of autoantibodies was not associated with gastrointestinal symptoms but sustains the presence of a pathophysiological link between bowel inflammation and SpA. Copyright (C) 2004 S. Karger AG, Basel
The impact of satellite temperature soundings on the forecasts of a small national meteorological service
The impact of introducing satellite temperature sounding data on a numerical weather prediction model of a national weather service is evaluated. A dry five level, primitive equation model which covers most of the Northern Hemisphere, is used for these experiments. Series of parallel forecast runs out to 48 hours are made with three different sets of initial conditions: (1) NOSAT runs, only conventional surface and upper air observations are used; (2) SAT runs, satellite soundings are added to the conventional data over oceanic regions and North Africa; and (3) ALLSAT runs, the conventional upper air observations are replaced by satellite soundings over the entire model domain. The impact on the forecasts is evaluated by three verification methods: the RMS errors in sea level pressure forecasts, systematic errors in sea level pressure forecasts, and errors in subjective forecasts of significant weather elements for a selected portion of the model domain. For the relatively short range of the present forecasts, the major beneficial impacts on the sea level pressure forecasts are found precisely in those areas where the satellite sounding are inserted and where conventional upper air observations are sparse. The RMS and systematic errors are reduced in these regions. The subjective forecasts of significant weather elements are improved with the use of the satellite data. It is found that the ALLSAT forecasts are of a quality comparable to the SAR forecasts
The flux phase problem on the ring
We give a simple proof to derive the optimal flux which minimizes the ground
state energy in one dimensional Hubbard model, provided the number of particles
is even.Comment: 8 pages, to appear in J. Phys. A: Math. Ge
Mod/Resc Parsimony Inference
We address in this paper a new computational biology problem that aims at
understanding a mechanism that could potentially be used to genetically
manipulate natural insect populations infected by inherited, intra-cellular
parasitic bacteria. In this problem, that we denote by \textsc{Mod/Resc
Parsimony Inference}, we are given a boolean matrix and the goal is to find two
other boolean matrices with a minimum number of columns such that an
appropriately defined operation on these matrices gives back the input. We show
that this is formally equivalent to the \textsc{Bipartite Biclique Edge Cover}
problem and derive some complexity results for our problem using this
equivalence. We provide a new, fixed-parameter tractability approach for
solving both that slightly improves upon a previously published algorithm for
the \textsc{Bipartite Biclique Edge Cover}. Finally, we present experimental
results where we applied some of our techniques to a real-life data set.Comment: 11 pages, 3 figure
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