363 research outputs found

    A study of real-time computer graphic display technology for aeronautical applications

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    Hardware, algorithms and software for real-time raster graphics were designed and implemented

    Calculus and heat flow in metric measure spaces and applications to spaces with Ricci bounds from below

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    This paper is devoted to a deeper understanding of the heat flow and to the refinement of calculus tools on metric measure spaces (X,d,m). Our main results are: - A general study of the relations between the Hopf-Lax semigroup and Hamilton-Jacobi equation in metric spaces (X,d). - The equivalence of the heat flow in L^2(X,m) generated by a suitable Dirichlet energy and the Wasserstein gradient flow of the relative entropy functional in the space of probability measures P(X). - The proof of density in energy of Lipschitz functions in the Sobolev space W^{1,2}(X,d,m). - A fine and very general analysis of the differentiability properties of a large class of Kantorovich potentials, in connection with the optimal transport problem. Our results apply in particular to spaces satisfying Ricci curvature bounds in the sense of Lott & Villani [30] and Sturm [39,40], and require neither the doubling property nor the validity of the local Poincar\'e inequality.Comment: Minor typos corrected and many small improvements added. Lemma 2.4, Lemma 2.10, Prop. 5.7, Rem. 5.8, Thm. 6.3 added. Rem. 4.7, Prop. 4.8, Prop. 4.15 and Thm 4.16 augmented/reenforced. Proof of Thm. 4.16 and Lemma 9.6 simplified. Thm. 8.6 corrected. A simpler axiomatization of weak gradients, still equivalent to all other ones, has been propose

    The in vitro effects of resistin on the innate immune signaling pathway in isolated human subcutaneous adipocytes

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    Context: Obesity-associated inflammation is a contributory factor in the pathogenesis of type 2 diabetes mellitus (T2DM); the mechanisms underlying the progression to T2DM are unclear. The adipokine resistin has demonstrated pro-inflammatory properties in relation to obesity and T2DM. Objective: To characterize resistin expression in human obesity and address the role of resistin in the innate immune pathway. Furthermore, examine the influence of lipopolysaccharide, recombinant human resistin (rhResistin), insulin and rosiglitazone in human adipocytes. Finally, analyze the effect of rhResistin on the expression of components of the NF-ÎșB pathway and insulin signaling cascade. Methods: Abdominal subcutaneous adipose tissue was obtained from patients undergoing elective liposuction surgery (n = 35, aged: 36-49 yr; BMI: 26.5 ± 5.9 kg/m2). Isolated adipocytes were cultured with rhResistin (10-50 ng/ml). The level of cytokine secretion from isolated adipocytes was examined by ELISA. The effect of rhResistin on protein expression of components of the innate immune pathway was examined by Western blot. Results: In-vitro studies demonstrated that antigenic stimuli increase resistin secretion (P < 0.001) from isolated adipocytes. Pro-inflammatory cytokine levels were increased in response to rhResistin (P < 0.001); this was attenuated by rosiglitazone (P < 0.01). When examining components of the innate immune pathway, rhResistin stimulated Toll-like receptor-2 protein expression. Similarly, mediators of the insulin signaling pathway, phosphospecific JNK1 and JNK2, were upregulated in response to rhResistin. Conclusion: Resistin may participate in more than one mechanism to influence pro-inflammatory cytokine release from human adipocytes; potentially via the integration of NF-ÎșB and JNK signaling pathways

    Blood pressure, lipids, and obesity are associated with reteinopathy - The Hoorn study

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    OBJECTIVE - To study potential risk factors for retinopathy in diabetic and nondiabetic individuals. RESEARCH DESIGN AND METHODS - The Hoorn Study is a population-based study including 2,484 50- to 74-year-old Caucasians. A subsample of 626 individuals stratified by age, sex, and glucose tolerance underwent extensive measurements during 1989-1992, including ophthalmologic examination and two-field 45-degree fundus photography. The prevalence of (diabetic) retinopathy was assessed among individuals with normal glucose metabolism (NGM) and impaired glucose metabolism (IGM) and individuals with newly diagnosed diabetes mellitus (NDM) and known diabetes mellitus (KDM) (new World Health Organization 1999 criteria). RESULTS - The prevalence of retinopathy was 9% in NGM, 11% in IGM, 13% in NDM, and 34% in KDM. Retinopathy worse than minimal nonproliferative diabetic retinopathy was present in 8% in KDM and 0-2% in other glucose categories. The prevalence of retinopathy was positively associated with elevated blood pressure, BMI, cholesterol, and triglyceride serum levels in all glucose categories. The age-, sex-, and glucose metabolism category-adjusted odds ratios were 1.5 (95% CI 1.2-1.9), 1.3 (1.0-1.7), and 1.3 (1.0-1.6) per SD increase of systolic blood pressure, BMI, and total cholesterol concentration, respectively, and 1.2 (1.0-1.5) per 50% increase of triglyceride level. Elevated blood pressure and plasma total and LDL cholesterol levels showed associations with retinal hard exudates. CONCLUSIONS - Retinopathy is a multifactorial microvascular complication, which, apart from hyperglycemia, is associated with blood pressure, lipid concentrations, and BMI

    Dissolving the digital divide : Creating coherence in young people's social ecologies of learning and identity building

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    This chapter discusses current research on educational efforts to connect school learning with young people’s digital practices in- and out-of-school. Instead of focusing on divides between in-school and out-of-school learning or between the “digital generation” and other age groups, in this chapter we discuss what recent research says about the ways in which school can become a space in which young people’s digital practices can transformatively converge with schooling, and how this convergence is related to their learning and identity building. We begin our narrative reflection of current research by focusing on the myth of digital natives. Next, we will conceptualize recent efforts to researching and understanding young people’s engagement, learning and identity building across sites and contexts. We will then turn to illuminating some key rationales of current educational research on creating convergence in young people’s social ecologies via the use of digital technologies and media. We conclude our reflections by pointing out that although there are some promising findings on how digital technologies and media can create convergence in young people’s engagement and learning across sites and contexts, less research attention is given to young people’s personal sense-making and self-making mediated by their digital practices, and how formal education could build on those practices for academic, vocational and/or civic ends.Peer reviewe

    Observational and Physical Classification of Supernovae

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    This chapter describes the current classification scheme of supernovae (SNe). This scheme has evolved over many decades and now includes numerous SN Types and sub-types. Many of these are universally recognized, while there are controversies regarding the definitions, membership and even the names of some sub-classes; we will try to review here the commonly-used nomenclature, noting the main variants when possible. SN Types are defined according to observational properties; mostly visible-light spectra near maximum light, as well as according to their photometric properties. However, a long-term goal of SN classification is to associate observationally-defined classes with specific physical explosive phenomena. We show here that this aspiration is now finally coming to fruition, and we establish the SN classification scheme upon direct observational evidence connecting SN groups with specific progenitor stars. Observationally, the broad class of Type II SNe contains objects showing strong spectroscopic signatures of hydrogen, while objects lacking such signatures are of Type I, which is further divided to numerous subclasses. Recently a class of super-luminous SNe (SLSNe, typically 10 times more luminous than standard events) has been identified, and it is discussed. We end this chapter by briefly describing a proposed alternative classification scheme that is inspired by the stellar classification system. This system presents our emerging physical understanding of SN explosions, while clearly separating robust observational properties from physical inferences that can be debated. This new system is quantitative, and naturally deals with events distributed along a continuum, rather than being strictly divided into discrete classes. Thus, it may be more suitable to the coming era where SN numbers will quickly expand from a few thousands to millions of events.Comment: Extended final draft of a chapter in the "SN Handbook". Comments most welcom

    Human Adenovirus Type 36 Enhances Glucose Uptake in Diabetic and Nondiabetic Human Skeletal Muscle Cells Independent of Insulin Signaling

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    OBJECTIVE—Human adenovirus type 36 (Ad-36) increases adiposity but improves insulin sensitivity in experimentally infected animals. We determined the ability of Ad-36 to increase glucose uptake by human primary skeletal muscle (HSKM) cells
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