1,788 research outputs found
Good Learning and Implicit Model Enumeration
MathSBML is an open-source, freely-downloadable Mathematica package that facilitates working with Systems Biology Markup Language (SBML) models. SBML is a toolneutral,computer-readable format for representing models of biochemical reaction networks, applicable to metabolic networks, cell-signaling pathways, genomic regulatory networks, and other modeling problems in systems biology that is widely supported by the systems biology community. SBML is based on XML, a standard medium for representing and transporting data that is widely supported on the internet as well as in computational biology and bioinformatics. Because SBML is tool-independent, it enables model transportability, reuse, publication and survival. In addition to MathSBML, a number of other tools that support SBML model examination and manipulation are provided on the sbml.org website, including libSBML, a C/C++ library for reading SBML models; an SBML Toolbox for MatLab; file conversion programs; an SBML model validator and visualizer; and SBML specifications and schemas. MathSBML enables SBML file import to and export from Mathematica as well as providing an API for model manipulation and simulation
Flavour structure of low-energy hadron pair photoproduction
We consider the process where and
are either mesons or baryons. The experimental findings for such quantities as
the and differential cross sections, in the energy range
currently probed, are found often to be in disparity with the scaling behaviour
expected from hard constituent scattering. We discuss the long-distance
pole--resonance contribution in understanding the origin of these phenomena, as
well as the amplitude relations governing the short-distance contribution which
we model as a scaling contribution. When considering the latter, we argue that
the difference found for the and the integrated cross
sections can be attributed to the s-channel isovector component. This
corresponds to the subprocess in the VMD
(vector-meson-dominance) language. The ratio of the two cross sections is
enhanced by the suppression of the component, and is hence constrained.
We give similar constraints to a number of other hadron pair production
channels. After writing down the scaling and pole--resonance contributions
accordingly, the direct summation of the two contributions is found to
reproduce some salient features of the and data.Comment: 12 pages, 9 figures, revised version to be published in EPJ
Study of the stability of a paramagnetic label linked to mesoporous silica surface in contact with rat mesothelial cells in culture.
Stable radicals detectable by electron paramagnetic resonance (EPR) may be use in the investigation of early events in cell-particle toxicity. Piperidine-N-oxyl derivatives (nitroxides), covalently linked to the surface of a high surface area silica (used as model solid for the technique), served as probes in the investigation of the effects of incubation of silica particles with mesothelial cells. A mesoporous silica (MCM-41), prepared by precipitation from a micellar solution, was the most appropriate silica-based particle for this purpose, as its channels allow direct contact with small molecules but not with macromolecules. The cytotoxicity of this amorphous silica is very low, allowing relatively high particle loading in the cell cultures. Both the high surface area of the sample and the large amount of inorganic material extracted from the cell culture provide enough material to run reasonably intense EPR spectra. Computer-aided analysis of the EPR spectra of silica-bound nitroxides provided information on the sensitivity of the labeled silica monitoring different environments, e.g., to follow the path of particles in a mammalian cell culture. Upon contact of the particles with mesothelial cells, the mean distance among the labels at the silica surface decreased as a consequence of the release of oxidizing and/or radical moieties from the cells
Suivi temps réel de personnes dans des séquences d'images couleur
Nous proposons dans cet article un algorithme temps réel de suivi de personnes, il est entièrement non supervisé, il ne nécessite aucune initialisation ni sur les modèles de pistes, ni sur leur nombre qui peut évoluer dans le temps. Il permet de gérer divers problèmes tels que les occlusions et les sous ou sur segmentations. La première étape du processus consiste à détecter les zones en mouvement. Les différentes régions ainsi obtenues seront affectées à des trajectoires en utilisant le concept de pistes élémentaires. Ces dernières nous permettent d'une part de faciliter le suivi et d'autre part de détecter les sorties d'occlusions en introduisant des ensembles cohérents de régions sur lesquels des modèles cinématiques, de forme ou de couleur pourront être définis. . Des résultats significatifs seront présentés sur des séquences réelles avec vérité de terrain
Bosonic Quartic Couplings at LHC
We analyze the potential of the CERN Large Hadron Collider (LHC) to study
anomalous quartic vector-boson interactions Z Z gamma gamma, Z Z Z gamma, W+ W-
gamma gamma, and W+ W- Z gamma through the weak boson fusion processes q q -> q
q gamma gamma and q q -> q q gamma Z(-> l+ l-) with l = electron or muon. After
a careful study of the backgrounds and how to extract them from the data, we
show that the process p p -> j j gamma l+ l- is potentially the most sensitive
to deviations from the Standard Model, improving the sensitivity to anomalous
couplings by up to a factor 10^4 (10^2) with respect to the present direct
(indirect) limits.Comment: 18 pages, 2 figures, revised versio
Events with Isolated Charged Leptons and Large Missing Transverse Momentum at HERA
Striking events with isolated charged leptons, large missing transverse
momentum and large transverse momentum of the hadronic final state were
observed at the electron proton collider HERA in a data sample corresponding to
a luminosity of about 130 pb-1. The H1 collaboration observed 11 events with
isolated electrons or muons and with transverse momentum above 25 GeV. Only
3.4+-0.6 events were expected from Standard Model (SM) processes. Six of these
events have a transverse momentum of greater than 40 GeV, while 1.3+-0.3 events
were expected. The ZEUS collaboration observed good agreement with the SM.
However, ZEUS found two events with a similar event topology, but tau leptons
instead of electrons or muons in the final state. Only 0.2+-0.05 events were
expected from SM processes. For various hypotheses the compatibility of the
experimental results was investigated with respect to the SM and with respect
to possible explanations beyond the SM. Prospects for the high-luminosity
HERA-II data taking period are given
Extraction de trajectoires basée sur la cinématique dans les séquences d'images
- Le suivi de personnes en mouvements sans aucune connaissance à priori du nombre de personnes présentes dans la scène et en prenant en compte les différents problèmes d'occlusions, s'avère difficile. Une détection de mouvement nous permet d'avoir des régions avec un nombre important de sous-segmentations et de sur-segmentations dues aux mauvaises conditions d'acquisition. L'étape de suivi qui doit prendre en compte tous ces problèmes, est réalisée avec l'algorithme EM (Expectation Maximization). Ce dernier utilise un model cinématique : on suppose que le mouvement apparent est rectiligne et uniforme, cette hypothèse reste localement valide pour beaucoup d'applications. Grâce à cette approche, des résultats satisfaisants ont été obtenus sur plusieurs séquences et ce sans aucune initialisation préalable
Engineered arrays of NV color centers in diamond based on implantation of CN- molecules through nanoapertures
We report a versatile method to engineer arrays of nitrogen-vacancy (NV)
color centers in dia- mond at the nanoscale. The defects were produced in
parallel by ion implantation through 80 nm diameter apertures patterned using
electron beam lithography in a PMMA layer deposited on a diamond surface. The
implantation was performed with CN- molecules which increased the NV defect
formation yield. This method could enable the realization of a solid-state
coupled-spin array and could be used for positioning an optically active NV
center on a photonic microstructure.Comment: 12 pages, 3 figure
Highlighting continued uncertainty in global land cover maps for the user community
In the last 10 years a number of new global datasets have been created and new, more sophisticated alorithms have been designed to classify land cover. GlobCover and MODIS v.5 are the most recent global land cover products available, where GlobCover (300 m) has the finest spatial resolution of other comparable products such as MODIS v.5 (50 m) and GLC-2000 (1 km). This letter shows that the thematic accuracy in the cropland domain has decreased when comparing these two latest products. This disagreement is also evident spatially when examining maps of cropland and forest disargeement between GLC-2000, MODIS and GlobCover. The analysis highlights the continued uncertainty surrounding these prducts, with a combined forest and cropland disagreement of 893 Mha (GlobCover versus MODIS v.5). This letter suggests that data sharing efforts and the provision of more 'in situ' data for training, calibration and validation are very important conditions for improving future global land cover products
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