640 research outputs found
Practical Use of Formal Concept Analysis in Service-Oriented Computing
International audiencePervasive applications are encountered in a number of settings, including smart houses, intelligent buildings or connected plants. Service-Oriented Computing is today the technology of choice for implementing and exposing resources in such environments. The selection of appropriate services at the right moment in order to compose meaningful applications is however a real issue. In this paper, we propose a FCA-based solution to this problem.We have integrated FCA algorithms in our pervasive gateways and adapted them in order to allow efficient runtime selection of heterogeneous and dynamic services. This work has been applied to realistic use cases in the scope of a European project
LP-based Covering Games with Low Price of Anarchy
We present a new class of vertex cover and set cover games. The price of
anarchy bounds match the best known constant factor approximation guarantees
for the centralized optimization problems for linear and also for submodular
costs -- in contrast to all previously studied covering games, where the price
of anarchy cannot be bounded by a constant (e.g. [6, 7, 11, 5, 2]). In
particular, we describe a vertex cover game with a price of anarchy of 2. The
rules of the games capture the structure of the linear programming relaxations
of the underlying optimization problems, and our bounds are established by
analyzing these relaxations. Furthermore, for linear costs we exhibit linear
time best response dynamics that converge to these almost optimal Nash
equilibria. These dynamics mimic the classical greedy approximation algorithm
of Bar-Yehuda and Even [3]
Possible Fractional Quantum Hall Effect in Graphite
Measurements of basal plane longitudinal rho_b(B) and Hall rho_H(B)
resistivities were performed on highly oriented pyrolytic graphite (HOPG)
samples in pulsed magnetic field up to B = 50 T applied perpendicular to
graphene planes, and temperatures 1.5 K 30 T and for all
studied samples, we observed a sign change in rho_H(B) from electron- to
hole-like. For our best quality sample, the measurements revealed the
enhancement in rho_b(B) for B > 34 T (T = 1.8 K), presumably associated with
the field-driven charge density wave or Wigner crystallization transition.
Besides, well defined plateaus in rho_H(B) were detected in the ultra-quantum
limit revealing the signatures of fractional quantum Hall effect in graphite.Comment: 15 pages, including 4 figure
Neutrino detection of transient sources with optical follow-up observations
The ANTARES telescope has the opportunity to detect transient neutrino
sources, such as gamma-ray bursts (GRBs), core-collapse supernovae (SNe),
flares of active galactic nuclei (AGNs)... To enhance the sensitivity to these
sources, we are developing a new detection method based on the observation of
neutrino bursts followed by an optical detection. The ANTARES Collaboration is
implementing a fast on-line event reconstruction with a good angular
resolution. These characteristics allow to trigger an optical telescope network
in order to identify the nature of the neutrinos (and high energy cosmic-rays)
sources. This follow-up can be done with a network of small automatic
telescopes and required a small observation time. An optical follow-up of
special events, such as neutrino doublets in coincidence in time and space or
single neutrino having a very high energy, would not only give access to the
nature of the sources but also improve the sensitivity for neutrino detection
from SNe or GRBs.Comment: 4 pages, proceeding for the SF2A general assembly June 200
Compartmentalization of distinct cAMP signaling pathways in mammalian sperm.
Fertilization competence is acquired in the female tract in a process known as capacitation. Capacitation is needed for the activation of motility (e.g. hyperactivation) and to prepare the sperm for an exocytotic process known as acrosome reaction. While the HCO3--dependent soluble adenylyl cyclase Adcy10 plays a role in motility, less is known about the source of cAMP in the sperm head. Transmembrane adenylyl cyclases (tmACs) are another possible source of cAMP. These enzymes are regulated by stimulatory heterotrimeric Gs proteins; however, the presence of Gs or tmACs in mammalian sperm has been controversial. In this manuscript, we used Western blotting and cholera toxin-dependent ADP ribosylation to show Gs presence in the sperm head. Also, we showed that forskolin, a tmAC specific activator, induces cAMP accumulation in sperm from both WT and Adcy10 null mice. This increase is blocked by the tmAC inhibitor SQ-22536 but not by the Adcy10 inhibitor KH7. While Gs immunoreactivity and tmAC activity are detected in the sperm head, PKA is only found in the tail, where Adcy10 was previously shown to reside. Consistent with an acrosomal localization, Gs reactivity is lost in acrosome reacted sperm, and forskolin is able to increase intracellular Ca2+ and induce the acrosome reaction. Altogether, these data suggest that cAMP pathways are compartmentalized in sperm, with Gs and tmAC in the head and Adcy10 and PKA in the flagellum.Fil: Wertheimer Hermitte, Eva Victoria. University Of Massachussets; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Krapf, Dario. Universidad Nacional de Rosario; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Biología Molecular y Celular de Rosario; ArgentinaFil: de la Vega Beltran, José L.. Universidad Nacional Autónoma de México; MéxicoFil: Sánchez Cárdenas, Claudia. Universidad Nacional Autónoma de México; MéxicoFil: Navarrete, Felipe. University Of Massachussets; Estados UnidosFil: Haddad, Douglas. University Of Massachussets; Estados UnidosFil: Escoffier, Jessica. University Of Massachussets; Estados UnidosFil: Salicioni, Ana M.. University Of Massachussets; Estados UnidosFil: Levin, Lonny R.. Cornell University; Estados UnidosFil: Buck, Jochen. Cornell University; Estados UnidosFil: Mager, Jesse. University Of Massachussets; Estados UnidosFil: Darszon, Alberto. Universidad Nacional Autónoma de México; MéxicoFil: Visconti, Pablo E.. University Of Massachussets; Estados Unido
Measurement of GEp/GMp in ep -> ep to Q2 = 5.6 GeV2
The ratio of the electric and magnetic form factors of the proton, GEp/GMp,
was measured at the Thomas Jefferson National Accelerator Facility (JLab) using
the recoil polarization technique. The ratio of the form factors is directly
proportional to the ratio of the transverse to longitudinal components of the
polarization of the recoil proton in the elastic
reaction. The new data presented in this article span the range 3.5 < Q2 < 5.6
GeV2 and are well described by a linear Q2 fit. Also, the ratio QF2p/F1p
reaches a constant value above Q2=2 GeV2.Comment: 6 pages, 4 figures Added two names to the main author lis
Recoil Polarization Measurements for Neutral Pion Electroproduction at Q^2=1 (GeV/c)^2 Near the Delta Resonance
We measured angular distributions of differential cross section, beam
analyzing power, and recoil polarization for neutral pion electroproduction at
Q^2 = 1.0 (GeV/c)^2 in 10 bins of W across the Delta resonance. A total of 16
independent response functions were extracted, of which 12 were observed for
the first time. Comparisons with recent model calculations show that response
functions governed by real parts of interference products are determined
relatively well near 1.232 GeV, but variations among models is large for
response functions governed by imaginary parts and for both increases rapidly
with W. We performed a nearly model-independent multipole analysis that adjusts
complex multipoles with high partial waves constrained by baseline models.
Parabolic fits to the W dependence of the multipole analysis around the Delta
mass gives values for SMR = (-6.61 +/- 0.18)% and EMR = (-2.87 +/- 0.19)% that
are distinctly larger than those from Legendre analysis of the same data.
Similarly, the multipole analysis gives Re(S0+/M1+) = (+7.1 +/- 0.8)% at
W=1.232 GeV, consistent with recent models, while the traditional Legendre
analysis gives the opposite sign because its truncation errors are quite
severe. Finally, using a unitary isobar model (UIM), we find that excitation of
the Roper resonance is dominantly longitudinal with S1/2 = (0.05 +/- 0.01)
GeV^(-1/2) at Q^2=1. The ReS0+ and ReE0+ multipoles favor pseudovector coupling
over pseudoscalar coupling or a recently proposed mixed-coupling scheme, but
the UIM does not reproduce the imaginary parts of 0+ multipoles well.Comment: 60 pages, 54 figure
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