635 research outputs found
Interpolated inequalities between exponential and Gaussian, Orlicz hypercontractivity and isoperimetry
We introduce and study a notion of Orlicz hypercontractive semigroups. We
analyze their relations with general -Sobolev inequalities, thus extending
Gross hypercontractivity theory. We provide criteria for these Sobolev type
inequalities and for related properties. In particular, we implement in the
context of probability measures the ideas of Maz'ja's capacity theory, and
present equivalent forms relating the capacity of sets to their measure. Orlicz
hypercontractivity efficiently describes the integrability improving properties
of the Heat semigroup associated to the Boltzmann measures , when . As an application
we derive accurate isoperimetric inequalities for their products. This
completes earlier works by Bobkov-Houdr\'e and Talagrand, and provides a scale
of dimension free isoperimetric inequalities as well as comparison theorems.Comment: 76 pages, 1 figur
Letter to the Editor: 1H, 15N, and 13C chemical shift assignments of the resuscitation promoting factor domain of Rv1009 from Mycobacterium tuberculosis
International audienceNo abstract availabl
Numerical study of tracers transport by a mesoscale convective system over West Africa
A three-dimensional cloud-resolving model is used to investigate the vertical
transport from the lower to the upper troposphere in a mesoscale convective
system (MCS) that occurred over Niger on 15 August 2004. The redistribution
of five passive tracers initially confined in horizontally homogeneous layers
is analyzed. The monsoon layer tracer (0â1.5 km) is the most efficiently
transported in the upper troposphere with concentrations 3 to 4 times higher
than the other tracers in the anvil. On the contrary the African Easterly Jet
tracer (~3 km) has the lowest contribution above 5 km. The vertical
profiles of the mid-troposphere tracers (4.5â10 km) in the MCS exhibit two
peaks: one in their initial layers, and the second one at 13â14 km altitude,
underlying the importance of mid-tropospheric air in feeding the upper
troposphere. Mid-tropospheric tracers also experience efficient transport by
convective downdrafts with a consequent increase of their concentrations at
the surface. The concentration of the upper troposphereâlower stratosphere
tracer exhibits strong gradients at the edge of the cloud, meaning almost no
entrainment of this tracer into the cloud. No downward transport from the
upper troposphere is simulated below 5 km. A proxy for lightning produced
NO<sub>x</sub> is transported preferentially in the forward anvil in the upper
troposphere. Additionally, lateral inflows significantly contribute to the
updraft and downdraft airflows emphasizing the three-dimensional structure of
the West African MCSs
Study of the optimal conditions for NV- center formation in type 1b diamond, using photoluminescence and positron annihilation spectroscopies
We studied the parameters to optimize the production of negatively-charged
nitrogen-vacancy color centers (NV-) in type~1b single crystal diamond using
proton irradiation followed by thermal annealing under vacuum. Several samples
were treated under different irradiation and annealing conditions and
characterized by slow positron beam Doppler-broadening and photoluminescence
(PL) spectroscopies. At high proton fluences another complex vacancy defect
appears limiting the formation of NV-. Concentrations as high as 2.3 x 10^18
cm^-3 of NV- have been estimated from PL measurements. Furthermore, we inferred
the trapping coefficient of positrons by NV-. This study brings insight into
the production of a high concentration of NV- in diamond, which is of utmost
importance in ultra-sensitive magnetometry and quantum hybrid systems
applications
Transference Principles for Log-Sobolev and Spectral-Gap with Applications to Conservative Spin Systems
We obtain new principles for transferring log-Sobolev and Spectral-Gap
inequalities from a source metric-measure space to a target one, when the
curvature of the target space is bounded from below. As our main application,
we obtain explicit estimates for the log-Sobolev and Spectral-Gap constants of
various conservative spin system models, consisting of non-interacting and
weakly-interacting particles, constrained to conserve the mean-spin. When the
self-interaction is a perturbation of a strongly convex potential, this
partially recovers and partially extends previous results of Caputo,
Chafa\"{\i}, Grunewald, Landim, Lu, Menz, Otto, Panizo, Villani, Westdickenberg
and Yau. When the self-interaction is only assumed to be (non-strongly) convex,
as in the case of the two-sided exponential measure, we obtain sharp estimates
on the system's spectral-gap as a function of the mean-spin, independently of
the size of the system.Comment: 57 page
SpecCert: Specifying and Verifying Hardware-based Security Enforcement
Over time, hardware designs have constantly grown in complexity and modern platforms involve multiple interconnected hardware components. During the last decade, several vulnerability disclosures have proven that trust in hardware can be misplaced. In this article, we give a formal definition of Hardware-based Security Enforcement (HSE) mechanisms, a class of security enforcement mechanisms such that a software component relies on the underlying hardware platform to enforce a security policy. We then model a subset of a x86-based hardware platform specifications and we prove the soundness of a realistic HSE mechanism within this model using Coq, a proof assistant system
Isoperimetry and stability of hyperplanes for product probability measures
International audienceWe investigate stationarity and stability of half-spaces as isoperimetric sets for product probability measures, considering the cases of coordinate and non-coordinate half-spaces. Moreover, we present several examples to which our results can be applied, with a particular emphasis on the logistic measure
Strong Coupling of a Spin Ensemble to a Superconducting Resonator
We report the realization of a quantum circuit in which an ensemble of
electronic spins is coupled to a frequency tunable superconducting resonator.
The spins are Nitrogen-Vacancy centers in a diamond crystal. The achievement of
strong coupling is manifested by the appearance of a vacuum Rabi splitting in
the transmission spectrum of the resonator when its frequency is tuned through
the NV center electron spin resonance.Comment: 4 pages, 3 figure
A Pre-expectation Calculus for Probabilistic Sensitivity
Sensitivity properties describe how changes to the input of a program affect the output, typically by upper bounding the distance between the outputs of two runs by a monotone function of the distance between the corresponding inputs. When programs are probabilistic, the distance between outputs is a distance between distributions. The Kantorovich lifting provides a general way of defining a distance between distributions by lifting the distance of the underlying sample space; by choosing an appropriate distance on the base space, one can recover other usual probabilistic distances, such as the Total Variation distance. We develop a relational pre-expectation calculus to upper bound the Kantorovich distance between two executions of a probabilistic program. We illustrate our methods by proving algorithmic stability of a machine learning algorithm, convergence of a reinforcement learning algorithm, and fast mixing for card shuffling algorithms. We also consider some extensions: using our calculus to show convergence of Markov chains to the uniform distribution over states and an asynchronous extension to reason about pairs of program executions with different control flow
PULSED AND CW LASER TREATMENTS OF IMPLANTED POLYSILICON SOLAR CELLS
Conventional ion implantation and unanalyzed ion bombardment have been used to elaborate the rectifying N+ contact of polycrystalline silicon (Wacker, HEM, CGE) solar cells. Two surface laser annealing in the liquid phase (Nd : YAG laser) and in the solid phase (CO2 laser) regimes have been used. The properties of the solar cells so processed have been investigated. For both doping procedures and both annealing techniques, the cells (conversion) efficiencies under AM1 illumination exceeded 11% for the various polysilicon substrates
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