751 research outputs found
Affine convex body semigroups
In this paper we present a new kind of semigroups called convex body
semigroups which are generated by convex bodies of R^k. They generalize to
arbitrary dimension the concept of proportionally modular numerical semigroup
of [7]. Several properties of these semigroups are proven. Affine convex body
semigroups obtained from circles and polygons of R^2 are characterized. The
algorithms for computing minimal system of generators of these semigroups are
given. We provide the implementation of some of them
Overview of adverse events related to invasive procedures in the intensive care unit
BackgroundThis study was conducted to determine the frequency, predictors, and clinical impact of adverse events (AEs) related to invasive procedures in the intensive care unit (ICU). Methods This was a prospective observational study of ICUs in a university hospital. Results A total of 893 patients requiring invasive procedures were admitted over a 1-year period. Among these, 310 patients (34.7%) experienced a total of 505 AEs. The mean number of AEs per patient was 1.6 ± 1.1 (range, 1-7). Infectious AEs were significantly more frequent than mechanical AEs (60.4% vs 39.6%; P = .01). Factors independently associated with AE occurrence were isolation of multidrug-resistant bacteria at ICU admission, >5 invasive procedures, and ICU length of stay >8 days. Thirty-three AEs (6.5%) resulted in severe clinical impact, including 24 deaths. Ventilator-associated pneumonia (VAP) accounted for 62.5% of the deaths related to AEs. Conclusions One-third of critically ill patients experienced AEs related to invasive procedures. Severe AEs were associated with 11% of all ICU deaths. VAP was the most frequent AE related to death. An improved assessment of the risk–benefit balance before each invasive procedure and increased efforts to decrease VAP prevalence are needed to reduce AE-related mortality
A certifying frontend for (sub)polyhedral abstract domains
Convex polyhedra provide a relational abstraction of numerical properties for static analysis of programs by abstract interpretation. We describe a lightweight certification of polyhedral abstract domains using the Coq proof assistant. Our approach consists in delegating most computations to an untrusted backend and in checking its outputs with a certified frontend. The backend is free to implement relaxations of domain operators in order to trade some precision for more efficiency, but must produce hints about the soundness of its results. Experiments with a full-precision backend show that the certification overhead is small and that the certified abstract domain has comparable performance to non-certifying state-of-the-art implementations
INVOLVEMENT OF RESPIRATORY CHAIN IN BIOFILM FORMATION IN PORPHYROMONAS GINGIVALIS
Oral Communication presented at the ";Forum des Jeunes Chercheurs";, Brest (France) 2011
A linear nonequilibrium thermodynamics approach to optimization of thermoelectric devices
Improvement of thermoelectric systems in terms of performance and range of
applications relies on progress in materials science and optimization of device
operation. In this chapter, we focuse on optimization by taking into account
the interaction of the system with its environment. For this purpose, we
consider the illustrative case of a thermoelectric generator coupled to two
temperature baths via heat exchangers characterized by a thermal resistance,
and we analyze its working conditions. Our main message is that both electrical
and thermal impedance matching conditions must be met for optimal device
performance. Our analysis is fundamentally based on linear nonequilibrium
thermodynamics using the force-flux formalism. An outlook on mesoscopic systems
is also given.Comment: Chapter 14 in "Thermoelectric Nanomaterials", Editors Kunihito
Koumoto and Takao Mori, Springer Series in Materials Science Volume 182
(2013
Accumulation of Self-Reactive Naive and Memory B Cell Reveals Sequential Defects in B Cell Tolerance Checkpoints in Sjogren's Syndrome
This work was funded by grants number 18237 and 20089 from Arthritis Research UK (http://www.arthritisresearchuk.org) to MB and the William Harvey Research Foundation. EC was recipient of short-term travel fellowships from EMBO (ASTF 318-2010) and EFIS-IL
Increased insolation threshold for runaway greenhouse processes on Earth like planets
Because the solar luminosity increases over geological timescales, Earth
climate is expected to warm, increasing water evaporation which, in turn,
enhances the atmospheric greenhouse effect. Above a certain critical
insolation, this destabilizing greenhouse feedback can "runaway" until all the
oceans are evaporated. Through increases in stratospheric humidity, warming may
also cause oceans to escape to space before the runaway greenhouse occurs. The
critical insolation thresholds for these processes, however, remain uncertain
because they have so far been evaluated with unidimensional models that cannot
account for the dynamical and cloud feedback effects that are key stabilizing
features of Earth's climate. Here we use a 3D global climate model to show that
the threshold for the runaway greenhouse is about 375 W/m, significantly
higher than previously thought. Our model is specifically developed to quantify
the climate response of Earth-like planets to increased insolation in hot and
extremely moist atmospheres. In contrast with previous studies, we find that
clouds have a destabilizing feedback on the long term warming. However,
subsident, unsaturated regions created by the Hadley circulation have a
stabilizing effect that is strong enough to defer the runaway greenhouse limit
to higher insolation than inferred from 1D models. Furthermore, because of
wavelength-dependent radiative effects, the stratosphere remains cold and dry
enough to hamper atmospheric water escape, even at large fluxes. This has
strong implications for Venus early water history and extends the size of the
habitable zone around other stars.Comment: Published in Nature. Online publication date: December 12, 2013.
Accepted version before journal editing and with Supplementary Informatio
New ELISA for B Cell-Activating Factor
Item does not contain fulltextWorkshop Theory and Methodology - 26th ISAGA Conference, 18 juli 1995Valencia, Spain : [S.n.]24 p
Chronic Erythropoietin Treatment Decreases Post-Infarct Myocardial Damage in Rats without Venous Thrombogenic Effect
Objectives: Whereas administration of erythropoietin (EPO) acutely after myocardial infarction (MI) reduces infarct size and chronic EPO therapy attenuates post-MI remodeling, the safety of chronic EPO therapy following MI is unknown. Therefore, we examined the thrombogenic effects of a chronic EPO therapy after MI.Methods: Rats underwent coronary occlusion followed by reperfusion. They were assigned to one of the following groups: EPO-A, single injection of EPO 5,000 U/kg at the time of reperfusion; EPO-C, injection of EPO 5,000 U/kg at the time of reperfusion followed by 300 U/kg/week; PBS-C, injection of vehicle only. After eight weeks of treatment they were exposed to a validated prethrombotic test based on partial stenosis of the inferior vena cava. Results: As compared to the rats receiving vehicle only, the rats treated with EPO exhibited a significant reduction in MI size (28.7 ± 2.1% and 25.8 ± 1.9 vs. 39.8 ± 3.0% in EPO-A, EPO-C and PBS-C, respectively; p < 0.05). Whereas the hematocrit was significantly increased in EPO-C (59.7 ± 2.0% vs. 44.7 ± 0.9% in EPO-A, p < 0.001), the proportion of rats in which a thrombus occurred was similar in all groups (p = 0.52). Conclusion: Chronic EPO therapy added to the single high dose of EPO injected acutely did not induce venous pro-thrombotic effect in rats
The use of indigenous knowledge in development: problems and challenges
The use of indigenous knowledge has been seen by many as an alternative way of promoting development in poor rural communities in many parts of the world. By reviewing much of the recent work on indigenous knowledge, the paper suggests that a number of problems and tensions has resulted in indigenous knowledge not being as useful as hoped for or supposed. These include problems emanating from a focus on the (arte)factual; binary tensions between western science and indigenous knowledge systems; the problem of differentiation and power relations; the romanticization of indigenous knowledge; and the all too frequent decontextualization of indigenous knowledge
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