1,550 research outputs found

    Numerical simulation of dark lanes in post-flare supra-arcade

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    We integrate the MHD ideal equations to simulate dark void sunwardly moving structures in post--flare supra--arcades. We study the onset and evolution of the internal plasma instability to compare with observations and to gain insight into physical processes and characteristic parameters of these phenomena. The numerical approach uses a finite-volume Harten-Yee TVD scheme to integrate the 1D1/2 MHD equations specially designed to capture supersonic flow discontinuities. The integration is performed in both directions, the sunward radial one and the transverse to the magnetic field. For the first time, we numerically reproduce observational dark voids described in Verwichte et al. (2005). We show that the dark tracks are plasma vacuums generated by the bouncing and interfering of shocks and expansion waves, upstream an initial slow magnetoacoustic shock produced by a localized deposition of energy modeled with a pressure perturbation. The same pressure perturbation produces a transverse to the field or perpendicular magnetic shock giving rise to nonlinear waves that compose the kink--like plasma void structures, with the same functional sunward decreasing phase speed and constancy with height of the period, as those determined by the observations.Comment: Accepted MNRAS, 6 pages, 7 figure

    Estudy the Effect of Breast Cancer on Tlr2 Expression in Nb4 Cell

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    Background: Breast cancer is the most common neoplasm in women and the most frequent cause of death in those between 35 and 55 years of age. All multicellular organisms have an innate immune system, whereas the adaptive or 'acquired' immune system is restricted to vertebrates. This study focused on the effect of conditioned medium isolated from cultured breast cancer cells on NB4 neutrophil-like cells. Materials and Methods: In the current study neutrophil-like NB4 cells were incubated with MCF-7 cell-conditioned medium. After 6 h incubation the intracellular receptor TLR2, was analyzed. Results: The results revealed that MCF-7 cell-conditioned medium elicited expression of TLR2 in NB4 cells. Conclusions: This treatment would result in the production of particular stimulants (i.e. soluble cytokines), eliciting the expression of immune system receptors. Furthermore, the flow cytometry results demonstrated that MCF-7 cell-conditioned medium elicited an effect on TLR2 intracellular receptors

    Social and clinical predictors of short- and long-term readmission after a severe exacerbation of copd

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    INTRODUCTION AND OBJECTIVES: The aim of this study was to evaluate the predictive ability of multiple social, and clinical factors for readmission after a severe acute exacerbation of COPD (AECOPD) during various time periods. METHODS: We performed a prospective cohort study in which recruited patients with AECOPD. We systematically collected numerous clinical (symptoms, pulmonary function, comorbidities, and treatment) and social (financial situation, housing situation, family support, caregiver overload, ability to perform activities, and risk of social exclusion) variables using several questionnaires and indices. The patients were followed closely for one year and readmissions at 30, 60, and 365 days were analysed. RESULTS: 253 patients were included, aged 68.9+/-9.8years, FEV1 = 42.1%+/-14.2%, and a Charlson's index = 1.8+/-0.9. Of these patients, 20.2%, 39.6%, and 63.7% were readmitted within the first 30, 90, and 365 days after discharge, respectively. In the multivariate model applied, the variables that were independently associated with readmission over all three periods of the analysis were dependence to perform basic activities of daily living (BADLs) (odds ratio [OR] = 2.10-4.10) and a history of two or more admissions within the previous year (OR = 2.78-3.78). At 90 days, a history of bacterial isolates in a previous sputum culture (OR = 2.39) and at 365 days, a high grade of dyspnoea (OR = 2.51) and obesity (OR = 2.38) were also identified as predictors of hospital readmission. CONCLUSIONS: The patients' limitation to perform BADLs and their history of admissions for AECOPD were the best predictive variables for the likelihood of readmission when adjusted for many other social and clinical variables, regardless of the time period considered for such prediction

    Physicochemical characterization of two cassava (Manihot esculenta Crantz)

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    P?ginas 19-25El almid?n y la harina de yuca fueron obtenidos de ra?ces cultivadas en Colombia en dos condiciones ambientales espec?ficas. Se evaluaron propiedades fisicoqu?micas como tama?o y morfolog?a del grano, contenido de amilosa, cristalinidad, propiedades t?rmicas y comportamiento al empastamiento. Las propiedades del almid?n de yuca fueron altamente influenciadas por las condiciones ambientales durante el periodo de crecimiento de las ra?ces de yuca. El almid?n extra?do de las ra?ces de yuca cultivadas en una zona con temperatura promedio m?s alta present? un tama?o de granulo m?s peque?o, mayor contenido de amilosa y mayor temperatura y entalpia de gelatinizaci?n, lo que est? relacionado con una mayor temperatura de empastamiento y menor viscosidad. Las harinas de yuca presentaron diferencias con los almidones estudiados como una menor entalpia de gelatinizaci?n medida por calorimetr?a diferencial de barrido (DSC), mayor temperatura de empastamiento y menor desarrollo de viscosidad m?xima. Este comportamiento posiblemente esta influenciado por la presencia de otros componentes diferentes al almid?n en la ra?z de yuca fresca.ABSTRACT. Starch and flour were produced from cassava roots grown in two specific environmental conditions in Colombia. The physicochemical properties evaluated were granule size and morphology, amylose content, crystal form, thermal properties and pasting behavior. The properties of cassava starch were highly influenced by the environmental conditions during the growth of the roots. Starch extracted from roots cultivated in a warmer zone showed smaller granule size, higher amylose content and higher temperature and enthalpy of gelatinization. This starch also showed higher pasting temperature and lower peak viscosity. Cassava flours presented differences with their corresponding starch such as lower enthalpy of gelatinization measured by DSC, higher pasting temperature and lower peak viscosity on pasting. It is possible that this behavior is influenced by the presence of non-starch components from the fresh root

    Deconstructing the Subject Condition in terms of cumulative constraint violation

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    Chomsky (1973) attributes the island status of nominal subjects to the Subject Condition, a constraint specific to subjects. English and Spanish are interesting languages for the comparative study of extraction from subjects, because subjects in English are predominantly preverbal, whereas in Spanish they can be either preverbal or postverbal. In this paper we argue that the islandhood of subject DPs in both English and Spanish is not categorical. The degradation associated with extraction from subjects must be attributed to the interplay of a range of more general constraints which are not specific to subjects. We argue that the interaction of these constraints has a cumulative effect whereby the more constraints that are violated, the higher the degree of degradation that results. We also argue that some speakers have a greater tolerance for constraint violations than others, which would account for widespread inter-speaker judgment variability

    Comparison of Bisulfite Pyrosequencing and Methylation-Specific qPCR for Methylation Assessment

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    Different methodological approaches are available to assess DNA methylation biomarkers. In this study, we evaluated two sodium bisulfite conversion-dependent methods, namely pyrosequencing and methylation-specific qPCR (MS-qPCR), with the aim of measuring the closeness of agreement of methylation values between these two methods and its effect when setting a cut-off. Methylation of tumor suppressor gene p16/INK4A was evaluated in 80 lung cancer patients from which cytological lymph node samples were obtained. Cluster analyses were used to establish methylated and unmethylated groups for each method. Agreement and concordance between pyrosequencing and MS-qPCR was evaluated with Pearson's correlation, Bland-Altman, Cohen's kappa index and ROC curve analyses. Based on these analyses, cut-offs were derived for MS-qPCR. An acceptable correlation (Pearson's R2 = 0.738) was found between pyrosequencing (PYRmean) and MS-qPCR (NMP; normalized methylation percentage), providing similar clinical results when categorizing data as binary using cluster analysis. Compared to pyrosequencing, MS-qPCR tended to underestimate methylation for values between 0 and 15%, while for methylation >30% overestimation was observed. The estimated cut-off for MS-qPCR data based on cluster analysis, kappa-index agreement and ROC curve analysis were much lower than that derived from pyrosequencing. In conclusion, our results indicate that independently of the approach used for estimating the cut-off, the methylation percentage obtained through MS-qPCR is lower than that calculated for pyrosequencing. These differences in data and therefore in the cut-off should be examined when using methylation biomarkers in the clinical practice

    Drug Delivery to the Posterior Segment of the Eye: Biopharmaceutic and Pharmacokinetic Considerations

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    The treatment of the posterior-segment ocular diseases, such as age-related eye diseases (AMD) or diabetic retinopathy (DR), present a challenge for ophthalmologists due to the complex anatomy and physiology of the eye. This specialized organ is composed of various static and dynamic barriers that restrict drug delivery into the target site of action. Despite numerous efforts, effective intraocular drug delivery remains unresolved and, therefore, it is highly desirable to improve the current treatments of diseases affecting the posterior cavity. This review article gives an overview of pharmacokinetic and biopharmaceutics aspects for the most commonly-used ocular administration routes (intravitreal, topical, systemic, and periocular), including information of the absorption, distribution, and elimination, as well as the benefits and limitations of each one. This article also encompasses different conventional and novel drug delivery systems designed and developed to improve drug pharmacokinetics intended for the posterior ocular segment treatment

    Classes of behavior of small-world networks

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    Small-world networks are the focus of recent interest because they appear to circumvent many of the limitations of either random networks or regular lattices as frameworks for the study of interaction networks of complex systems. Here, we report an empirical study of the statistical properties of a variety of diverse real-world networks. We present evidence of the occurrence of three classes of small-world networks: (a) scale-free networks, characterized by a vertex connectivity distribution that decays as a power law; (b) broad-scale networks, characterized by a connectivity distribution that has a power-law regime followed by a sharp cut-off; (c) single-scale networks, characterized by a connectivity distribution with a fast decaying tail. Moreover, we note for the classes of broad-scale and single-scale networks that there are constraints limiting the addition of new links. Our results suggest that the nature of such constraints may be the controlling factor for the emergence of different classes of networks
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