3,043 research outputs found

    Quenched invariance principles for the random conductance model on a random graph with degenerate ergodic weights

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    We consider a stationary and ergodic random field {ω(e):eEd}\{\omega(e) : e \in E_d\} that is parameterized by the edge set of the Euclidean lattice Zd\mathbb{Z}^d, d2d \geq 2. The random variable ω(e)\omega(e), taking values in [0,)[0, \infty) and satisfying certain moment bounds, is thought of as the conductance of the edge ee. Assuming that the set of edges with positive conductances give rise to a unique infinite cluster C(ω)\mathcal{C}_{\infty}(\omega), we prove a quenched invariance principle for the continuous-time random walk among random conductances under relatively mild conditions on the structure of the infinite cluster. An essential ingredient of our proof is a new anchored relative isoperimetric inequality.Comment: 22 page

    Bayesian Analysis Of Poverty Rates: The Case Of Vietnamese Provinces

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    This paper presents a Bayesian analysis of poverty rates in urban Ho Chi Minh City and rural Nghe An province in Vietnam. Using mixtures of beta distributions as priors for the poverty rates, we find that, when the prior is reasonably informative, our approach yields more accurate estimated poverty rates than a frequentist approach. On the other hand, we find that, in the presence of poor/non-poor misclassification, average probabilities of posterior credible intervals for poverty rates can fall well short of .95 even with sample sizes such as 2000 or 3000 when the width of the interval is for example four percentage points. In general, we suggest reporting prior and posterior means and standard deviations along with traditional frequentist measures. Our results rely on techniques due to Nandram and Sedransk (1993) and Rahme, Joseph and Gyorkos (2000), and make use of the software WINBUGS

    Production of fermentescible sugar from paper-pulp: looking for a dynamic and multiscale integrated models based on physical parameters

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    In order to achieve economic viability, the biorefining of lignocellulosic resources must be operated at very high feedstock dry matter content. The paper pulp product is rather appropriate for modern biorefining, because it displays low lignin content, is free of inhibitory compounds that can perturb fermentations and is devoid of microbial contaminants. Nevertheless the enzyme liquefaction and saccharification of paper-like pulps are subject to the same constraints as other pulps obtained via alternative methods such as steam explosion or dilute acid hydrolysis. Therefore, the better scientific understanding and ultimately the technical mastering of these critical biocatalytic reactions, which involve complex matrices at high solids content, is currently a major challenge that must be met in order to facilitate the intensification of biorefining operations. Our aim is to investigate dynamic of transfer phenomena and limitation of biocatalytic reactions with lignocelluloses resources under high concentration conditions. Our action focuses on the identification of rate limiting steps of the liquefactions mechanisms by physical and biochemical characterization of pre-treated lignocellulosic resources at a macroscopic scale (power consumption, rheology), microscopic scale (particle size, morphology) and molecular scale (chemical analysis). Firstly, based on real and model matrices and using Metzner & Reed concept, non-Newtonian rheological behaviour of fiber suspensions are described by a structured rheological model including parameters such as concentration, size and shape. Secondly, the complex relationships between fibre structure, degradation, chemical composition and rheological behaviour is investigated. To this end, physical and biochemical on line and off-line analyses will be conducted during bioreaction with a specific and fully instrumented bioprocess. Relation between apparent viscosity change and biocatalytic degradation of fiber may then be discussed

    Automatic detection of AutoPEEP during controlled mechanical ventilation.

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    International audienceABSTRACT: BACKGROUND: Dynamic hyperinflation, hereafter called AutoPEEP (auto-positive end expiratory pressure)with some slight language abuse, is a frequent deleterious phenomenon in patients undergoingmechanical ventilation. Although not readily quantifiable, AutoPEEP can be recognized onthe expiratory portion of the flow waveform. If expiratory flow does not return to zero beforethe next inspiration, AutoPEEP is present. This simple detection however requires the eye ofan expert clinician at the patient's bedside. An automatic detection of AutoPEEP should behelpful to optimize care. METHODS: In this paper, a platform for automatic detection of AutoPEEP based on the flow signalavailable on most of recent mechanical ventilators is introduced. The detection algorithms aredeveloped on the basis of robust non-parametric hypothesis testings that require no priorinformation on the signal distribution. In particular, two detectors are proposed: one is basedon SNT (Signal Norm Testing) and the other is an extension of SNT in the sequentialframework. The performance assessment was carried out on a respiratory system analog andex-vivo on various retrospectively acquired patient curves. RESULTS: The experiment results have shown that the proposed algorithm provides relevant AutoPEEPdetection on both simulated and real data. The analysis of clinical data has shown that theproposed detectors can be used to automatically detect AutoPEEP with an accuracy of 93%and a recall (sensitivity) of 90%. CONCLUSIONS: The proposed platform provides an automatic early detection of AutoPEEP. Such functionalitycan be integrated in the currently used mechanical ventilator for continuous monitoring of thepatient-ventilator interface and, therefore, alleviate the clinician task

    Epsilon-covering is NP-complete

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    International audienceConsider the dilation and erosion of a shape S by a ball of radius ε. We call ε-covering of S any collection of balls whose union lies between the dilation and erosion of S. We prove that finding an ε-covering of minimum cardinality is NP-complete, using a reduction from vertex cover

    Fully automated compound screening in Arabidopsis thaliana seedlings

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    High-throughput small molecule screenings in model plants are of great value to identify compounds that interfere with plant developmental processes. In academic research, the plant Arabidopsis thaliana is the most commonly used model organism for this purpose. However, compared to plant cellular systems, A. thaliana plants are less amenable to develop high-throughput screening assays. In this chapter, we describe a screening procedure that is compatible with liquid handling systems and increases the throughput of compound screenings in A. thaliana seedlings

    3D super-resolved in vitro multiphoton microscopy by saturation of excitation

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    We demonstrate a significant resolution enhancement beyond the conventional limit in multiphoton microscopy (MPM) using saturated excitation of fluorescence. Our technique achieves super-resolved imaging by temporally modulating the excitation laser-intensity and demodulating the higher harmonics from the saturated fluorescence signal. The improvement of the lateral and axial resolutions is measured on a sample of fluorescent microspheres. While the third harmonic already provides an enhanced resolution, we show that a further improvement can be obtained with an appropriate linear combination of the demodulated harmonics. Finally, we present in vitro imaging of fluorescent microspheres incorporated in HeLa cells to show that this technique performs well in biological samples

    A 3D quantitative method for analyzing bone mineral densities : a case study on skeletal deformities in the gilthead sea bream, Sparus aurata (Linnaeus, 1758)

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    Skeletal deformities, one of the major threats for aquaculture, have been studied extensively. These include opercular malformations in gilthead sea bream (Sparus aurata), a key fish species for Mediterranean aquaculture. What is causing it and at what morphogenetic level it arises, however, is still unclear. Here we focus on bone formation, at the level of bone mineralization. Several methods have been used to study bone mineralization density (BMD), however, these are frequently limited when targeting a high-resolution, three-dimensional mapping of BMD. We used micro-computed tomography (micro-CT) data to perform such a 3D quantification of BMD levels in gilthead sea bream that showed different levels of opercular bone deformations. This approach has the advantage of not having to rely on calibration phantoms, as long as relative BMD values are needed. The results show an increased BMD in deformed opercles compared to normal ones, especially in a bilaterally-deformed specimen. Furthermore, we show that opercular deformations are not necessarily associated with similar mineralization patterns in other mineralized cranial elements, except for the otoliths. Also, mineralization seems to occur left-right independently, matching earlier observations of such an independency of the opercular phenotype as a whole. This study confirms that a quantitative characterization of BMD patterns in 3D is feasible, even in smaller specimens, and that it has several advantages over other commonly used approaches
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