652 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
Relational reasoning via probabilistic coupling
Probabilistic coupling is a powerful tool for analyzing pairs of
probabilistic processes. Roughly, coupling two processes requires finding an
appropriate witness process that models both processes in the same probability
space. Couplings are powerful tools proving properties about the relation
between two processes, include reasoning about convergence of distributions and
stochastic dominance---a probabilistic version of a monotonicity property.
While the mathematical definition of coupling looks rather complex and
cumbersome to manipulate, we show that the relational program logic pRHL---the
logic underlying the EasyCrypt cryptographic proof assistant---already
internalizes a generalization of probabilistic coupling. With this insight,
constructing couplings is no harder than constructing logical proofs. We
demonstrate how to express and verify classic examples of couplings in pRHL,
and we mechanically verify several couplings in EasyCrypt
Computer-aided verification in mechanism design
In mechanism design, the gold standard solution concepts are dominant
strategy incentive compatibility and Bayesian incentive compatibility. These
solution concepts relieve the (possibly unsophisticated) bidders from the need
to engage in complicated strategizing. While incentive properties are simple to
state, their proofs are specific to the mechanism and can be quite complex.
This raises two concerns. From a practical perspective, checking a complex
proof can be a tedious process, often requiring experts knowledgeable in
mechanism design. Furthermore, from a modeling perspective, if unsophisticated
agents are unconvinced of incentive properties, they may strategize in
unpredictable ways.
To address both concerns, we explore techniques from computer-aided
verification to construct formal proofs of incentive properties. Because formal
proofs can be automatically checked, agents do not need to manually check the
properties, or even understand the proof. To demonstrate, we present the
verification of a sophisticated mechanism: the generic reduction from Bayesian
incentive compatible mechanism design to algorithm design given by Hartline,
Kleinberg, and Malekian. This mechanism presents new challenges for formal
verification, including essential use of randomness from both the execution of
the mechanism and from the prior type distributions. As an immediate
consequence, our work also formalizes Bayesian incentive compatibility for the
entire family of mechanisms derived via this reduction. Finally, as an
intermediate step in our formalization, we provide the first formal
verification of incentive compatibility for the celebrated
Vickrey-Clarke-Groves mechanism
A lightning climatology of the South-West Indian Ocean
The World Wide Lightning Location Network (WWLLN) data have been used to perform a lightning climatology in the South-West Indian Ocean (SWIO) region from 2005 to 2011. Maxima of lightning activity were found in the Maritime Continent and southwest of Sri Lanka (>50 fl km<sup>−2</sup> yr<sup>−1</sup>) but also over Madagascar and above the Great Lakes of East Africa (>10–20 fl km<sup>−2</sup> yr<sup>−1</sup>). Lightning flashes within tropical storms and tropical cyclones represent 50 % to 100 % of the total lightning activity in some oceanic areas of the SWIO (between 10° S and 20° S). <br><br> The SWIO is characterized by a wet season (November to April) and a dry season (May to October). As one could expect, lightning activity is more intense during the wet season as the Inter Tropical Convergence Zone (ITCZ) is present over all the basin. Flash density is higher over land in November–December–January with values reaching 3–4 fl km<sup>−2</sup> yr<sup>−1</sup> over Madagascar. During the dry season, lightning activity is quite rare between 10° S and 25° S. The Mascarene anticyclone has more influence on the SWIO resulting in shallower convection. Lightning activity is concentrated over ocean, east of South Africa and Madagascar. <br><br> A statistical analysis has shown that El Niño–Southern Oscillation mainly modulates the lightning activity up to 56.8% in the SWIO. The Indian Ocean Dipole has a significant contribution since ~49% of the variability is explained by this forcing in some regions. The Madden–Julian Oscillation did not show significative impact on the lightning activity in our study
Closure properties of solutions to heat inequalities
We prove that if are
sufficiently well-behaved solutions to certain heat inequalities on then
the function given by
also satisfies a heat inequality of a
similar type provided . On
iterating, this result leads to an analogous statement concerning -fold
convolutions. As a corollary, we give a direct heat-flow proof of the sharp
-fold Young convolution inequality and its reverse form.Comment: 12 page
Machine Assisted Proof of ARMv7 Instruction Level Isolation Properties
In this paper, we formally verify security properties of the ARMv7 Instruction Set Architecture (ISA) for user mode executions.
To obtain guarantees that arbitrary (and unknown) user processes are able to run isolated from privileged software and other user processes, instruction level noninterference and integrity properties are provided, along with proofs that transitions to privileged modes can only occur in a controlled manner.
This work establishes a main requirement for operating system and hypervisor verification, as demonstrated for the PROSPER separation kernel. The proof is performed in the HOL4 theorem prover, taking the Cambridge model of ARM as basis.
To this end, a proof tool has been developed, which assists the verification of relational state predicates semi-automatically
Sulfadimethoxine residues in rabbit muscle after extended oral treatment at therapeutic dosage
[EN] Sulfadimethoxine is extensively used in rabbit breeding for preventive and curative purpose and residues are sometimes observed in carcasses at slaughter. It has been suggested this is due to dosage and/or duration of treatment not being in compliance with the manufacturer's recommendations, which probably induces residue levels in the meat above the maximum residue limit (MRL) value of 100 ¿g/kg. In order to test this hypothesis, a study was carried out on gravid rabbits and their progeny. The animals were subjected to an extended treatment with sulfadimethoxine at therapeutic level in the feed. The feed was supplemented before pelleting with a commercial veterinary product containing 20 g of trimethoprim and 93 g of sulfadimethoxine per kg. On the basis of the dosage indicated for this commercial veterinary product, the incorporation level in the feed was 5 kg/ton (i.e. 465 g of sulfadimethoxine/ton), providing oral daily therapeutic treatment of the animals of ca. 12.5 to 50 mg of sulfadimethoxine per kg bodyweight. The mothers were treated during the last 21 d of pregnancy and during the whole period of lactation (35 d). The animals were sacrificed after a wash-out period of 12 d with blank feed. The young rabbits received the supplemented feed after weaning during the first 40 d of the fattening period. These animals were also sacrifi ced after a wash-out period of 8, 12, 15 or 20 d, respectively, with a blank feed. A sample of the leg muscle was taken for analysis. An HPLC analytical method was used to determine the sulfadimethoxine concentrations in tissue, with a LLOQ (Lower Limit Of Quantification) of 50 ¿g/kg of muscle (trimethoprim was not considered in this study). Sulfadimethoxine concentrations above the MRL value of 100 ¿g/kg were registered only in muscle from 1 out of 8 mothers and in 2 out of 8 young rabbits sacrificed 12 d after cessation of the treatment. For other young rabbits sacrificed on the 8th, 15th or 20th d after cessation of treatment, Sulphonamide concentrations in muscle always remained below the MRL value (8 animals per slaughtering time). These results show that oral treatment of rabbits with veterinary products containing sulfadimethoxine administered for a long period at the daily therapeutic level of 12.5 to 50 mg/kg does not seem to induce the accumulation of this molecule in muscle.Barthe, C.; Guicherd, A.; Quillon, J. (2009). Sulfadimethoxine residues in rabbit muscle after extended oral treatment at therapeutic dosage. World Rabbit Science. 17(3):137-144. doi:10.4995/wrs.2009.65313714417
Choix de localisation et mobilisation des ressources dans la création d'entreprises innovantes.
International audienceLa création d'entreprises innovantes est censée constituer un des moteurs du développement des systèmes locaux d'innovation, mais elle a rarement été étudiée sous l'angle spatial. Les entreprises innovantes tendent-elles à se regrouper dans l'espace ? Comment les fondateurs choisissent-ils leurs lieux d'implantations ? Comment se déploient dans l'espace les ressources mobilisées par les fondateurs ? Cet article fait le point sur ces questions à partir d'un corpus d'histoires de créations d'entreprises constituées sur la base d'entretiens croisés et d'analyse documentaire. L'accent sera en particulier mis sur les choix de localisation et les logiques de mobilisation de ressources dans leur dimension spatiale
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
07091 Abstracts Collection -- Mobility, Ubiquity and Security
From 25.02.2007 to 02.03.2007, the Dagstuhl Seminar 07091 ``Mobility,
Ubiquity and Security\u27\u27 was held in the International Conference and
Research Center (IBFI), Schloss Dagstuhl. During the seminar,
several participants presented their current research, and ongoing work and
open problems were discussed. Abstracts of the presentations given during
the seminar as well as abstracts of seminar results and ideas are put together
in this paper. The first section describes the seminar topics and goals
in general. Links to extended abstracts or full papers are provided,
if available
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