204 research outputs found

    Analyticity of Nonsymmetric Ornstein-Uhlenbeck Semigroup with Respect to a Weighted Gaussian Measure

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    In this paper we show that the realization in L p(X, ν∞) of a nonsymmetric Ornstein-Uhlenbeck operator Lp is sectorial for any p∈ (1 , + ∞) and we provide an explicit sector of analyticity. Here, (X, μ∞, H∞) is an abstract Wiener space, i.e., X is a separable Banach space, μ∞ is a centred nondegenerate Gaussian measure on X and H∞ is the associated Cameron-Martin space. Further, ν∞ is a weighted Gaussian measure, that is, ν∞= e−Uμ∞ where U is a convex function which satisfies some minimal conditions. Our results strongly rely on the theory of nonsymmetric Dirichlet forms and on the divergence form of the realization of L2 in L 2(X, ν∞)

    On coupled systems of Kolmogorov equations with applications to stochastic differential games

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    We prove that a family of linear bounded evolution operators (G(t,s))tsI({\bf G}(t,s))_{t\ge s\in I} can be associated, in the space of vector-valued bounded and continuous functions, to a class of systems of elliptic operators A\bm{\mathcal A} with unbounded coefficients defined in I\times \Rd (where II is a right-halfline or I=RI=\R) all having the same principal part. We establish some continuity and representation properties of (G(t,s))tsI({\bf G}(t,s))_{t \ge s\in I} and a sufficient condition for the evolution operator to be compact in C_b(\Rd;\R^m). We prove also a uniform weighted gradient estimate and some of its more relevant consequence

    Domains of elliptic operators on sets in Wiener space

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    Let X be a separable Banach space endowed with a non-degenerate centered Gaussian measure μ. The associated Cameron-Martin space is denoted by H. Consider two sufficiently regular convex functions U: X → R and G: X →R We let ν = e-Uμ and ω = G-1(-∞, 0]. In this paper, we study the domain of the self-adjoint operator associated with the quadratic form {equation presented} and we give sharp embedding results for it. In particular, we obtain a characterization of the domain of the Ornstein-Uhlenbeck operator in Hilbert space with ω = X and on half-spaces, namely if U 0 and G is an affine function, then the domain of the operator defined via (0.1) is the space u {equation presented}, where ρ is the Feyel-de La Pradelle Hausdorff-Gauss surface measure

    Accuracy and replicability in a non-discrete approach to the study of artificial craneal modification

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    El objetivo principal de este trabajo es explorar la precisión y replicabilidad de las técnicas de morfometría geométrica para la descripción del patrón de variación en las modificaciones artificiales del cráneo. Nuestra aproximación exhibe su gran capacidad descriptiva y la posibilidad de transformar la variación morfológica cualitativa en información cuantitativa continua. La variación descripta es continua en el morfoespacio de las modificaciones craneanas, demostrando que los casos estudiados no conforman grupos naturalmente discretos.The main objective of this paper is to explore the accuracy and repeatability of geometric morphometric techniques to describe the pattern of variation in artificial modifications of the skull. Our approach demonstrates a great descriptive capacity and the posibility of transforming quantitative morphological variation into continuous qualitative information. The variation described is continuous in the morpho-space of the cranial modifications, showing that the studied cases don not conform to naturally discrete groups.Fil: Serna, Alejandro. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División Arqueologia; Argentina;Fil: D´Addona, Lucas. Universidad Nacional de la Plata. Facultad de Cs.naturales y Museo. Div. Antropologia;Argentina;Fil: Perez, Sergio Ivan. Comision Nacional de Investigacion Cientifica y Tecnologica;Argentina

    Instabilities in a combustion model with two free interfaces

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    We study in a strip of R2 a combustion model of flame propagation with stepwise temperature kinetics and zero-order reaction, characterized by two free interfaces, respectively the ignition and the trailing fronts. The latter interface presents an additional difficulty because the non-degeneracy condition is not met. We turn the system to a fully nonlinear problem which is thoroughly investigated. When the width ℓ of the strip is sufficiently large, we prove the existence of a critical value Lec of the Lewis number Le, such that the one-dimensional, planar, solution is unstable for

    Rictor Phosphorylation on the THR-1135 Site Does Not Require Mammalian Target of Rapamycin Complex 2

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    available in PMC 2012 January 1.In animal cells, growth factors coordinate cell proliferation and survival by regulating the phosphoinositide 3-kinase/Akt signaling pathway. Deregulation of this signaling pathway is common in a variety of human cancers. The PI3K-dependent signaling kinase complex defined as mammalian target of rapamycin complex 2 (mTORC2) functions as a regulatory Ser-473 kinase of Akt. We find that activation of mTORC2 by growth factor signaling is linked to the specific phosphorylation of its component rictor on Thr-1135. The phosphorylation of this site is induced by the growth factor stimulation and expression of the oncogenic forms of ras or PI3K. Rictor phosphorylation is sensitive to the inhibition of PI3K, mTOR, or expression of integrin-linked kinase. The substitution of wild-type rictor with its specific phospho-mutants in rictor null mouse embryonic fibroblasts did not alter the growth factor–dependent phosphorylation of Akt, indicating that the rictor Thr-1135 phosphorylation is not critical in the regulation of the mTORC2 kinase activity. We found that this rictor phosphorylation takes place in the mTORC2-deficient cells, suggesting that this modification might play a role in the regulation of not only mTORC2 but also the mTORC2-independent function of rictor. Mol Cancer Res; 8(6); 896–906.University of Texas M.D. Anderson Cancer Center (Fellow Trust fund)American Cancer Society (M.D. Anderson Cancer Center Breast Specialized Programs of Research Excellence (RSG-09-026-01CCG01))National Institutes of Health (U.S.) (NIH grant CA133522)National Institutes of Health (U.S.) (NIH grant AI104389

    Cryogenic Propellant Storage and Transfer Technology Demonstration: Prephase A Government Point-of-Departure Concept Study

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    The primary purpose of this study was to define a point-of-departure prephase A mission concept for the cryogenic propellant storage and transfer technology demonstration mission to be conducted by the NASA Office of the Chief Technologist (OCT). The mission concept includes identification of the cryogenic propellant management technologies to be demonstrated, definition of a representative mission timeline, and definition of a viable flight system design concept. The resulting mission concept will serve as a point of departure for evaluating alternative mission concepts and synthesizing the results of industry- defined mission concepts developed under the OCT contracted studie

    The Location and Nature of General Anesthetic Binding Sites on the Active Conformation of Firefly Luciferase; A Time Resolved Photolabeling Study

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    Firefly luciferase is one of the few soluble proteins that is acted upon by a wide variety of general anesthetics and alcohols; they inhibit the ATP–driven production of light. We have used time–resolved photolabeling to locate the binding sites of alcohols during the initial light output, some 200 ms after adding ATP. The photolabel 3-azioctanol inhibited the initial light output with an IC50 of 200 µM, close to its general anesthetic potency. Photoincorporation of [3H]3-azioctanol into luciferase was saturable but weak. It was enhanced 200 ms after adding ATP but was negligible minutes later. Sequencing of tryptic digests by HPLC–MSMS revealed a similar conformation–dependence for photoincorporation of 3-azioctanol into Glu-313, a residue that lines the bottom of a deep cleft (vestibule) whose outer end binds luciferin. An aromatic diazirine analog of benzyl alcohol with broader side chain reactivity reported two sites. First, it photolabeled two residues in the vestibule, Ser-286 and Ile-288, both of which are implicated with Glu-313 in the conformation change accompanying activation. Second, it photolabeled two residues that contact luciferin, Ser-316 and Ser-349. Thus, time resolved photolabeling supports two mechanisms of action. First, an allosteric one, in which anesthetics bind in the vestibule displacing water molecules that are thought to be involved in light output. Second, a competitive one, in which anesthetics bind isosterically with luciferin. This work provides structural evidence that supports the competitive and allosteric actions previously characterized by kinetic studies

    Aptamer-based multiplexed proteomic technology for biomarker discovery

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    Interrogation of the human proteome in a highly multiplexed and efficient manner remains a coveted and challenging goal in biology. We present a new aptamer-based proteomic technology for biomarker discovery capable of simultaneously measuring thousands of proteins from small sample volumes (15 [mu]L of serum or plasma). Our current assay allows us to measure ~800 proteins with very low limits of detection (1 pM average), 7 logs of overall dynamic range, and 5% average coefficient of variation. This technology is enabled by a new generation of aptamers that contain chemically modified nucleotides, which greatly expand the physicochemical diversity of the large randomized nucleic acid libraries from which the aptamers are selected. Proteins in complex matrices such as plasma are measured with a process that transforms a signature of protein concentrations into a corresponding DNA aptamer concentration signature, which is then quantified with a DNA microarray. In essence, our assay takes advantage of the dual nature of aptamers as both folded binding entities with defined shapes and unique sequences recognizable by specific hybridization probes. To demonstrate the utility of our proteomics biomarker discovery technology, we applied it to a clinical study of chronic kidney disease (CKD). We identified two well known CKD biomarkers as well as an additional 58 potential CKD biomarkers. These results demonstrate the potential utility of our technology to discover unique protein signatures characteristic of various disease states. More generally, we describe a versatile and powerful tool that allows large-scale comparison of proteome profiles among discrete populations. This unbiased and highly multiplexed search engine will enable the discovery of novel biomarkers in a manner that is unencumbered by our incomplete knowledge of biology, thereby helping to advance the next generation of evidence-based medicine
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