3,597 research outputs found

    A dynamical and observational study of an unstable TNO: 59358 (1999CL158)

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    Context: The physical surface properties of a trans-Neptunian Object is believed to be mainly produced as a result of interplay between irradiation from different kinds of cosmic rays and collisions. Objects recently resurfaced by collisions are likely to have very different physical properties from those of the bulk population. In particular, pristine ices from the interior are expected to be present on the surface. A possible way to identify a trans-Neptunian object that has suffered a major collision is by investigating the lifetime of the orbit near its present location. If the lifetime is very short, a physical encounter is a possible way by which the TNO has evolved into such a short lived orbit. Aims: The goal of this investigation is to search for tracers of a young surface on objects with very short orbital lifetimes in the trans-Neptunian Belt. We are looking for any evidence that indicates that they reached their current unstable orbits through collisions. In particular, we have studied the case of 59358 (1999CL{158}), a trans-Neptunian object that currently has the most chaotic orbit in the Classical Belt. Methods: By numerically integration its orbit, we estimate that 59358 (1999CL{158}) has resided near its location for about 10 Myr. We have also obtained a near-infrared spectrum of 59358 (1999CL{158}) in the region between 1.43-1.96 microns using the near infrared imager and spectrograph, NIRI, at Gemini North 8-m telescope. These NIR observations are of the faintest and smallest TNO so far observed. Results: We present the results of the search of ice-bands, such as CH4 and H2O, having found evidence of the presence of the first mentioned molecule. Conclusions: The detection of methane implies that it must be an abundant component of this object. Methane is also evidence of a young surface, therefore we conclude that it is likely that 59358 (1999CL{158}) has experienced a recent collision or collisions. Based on observations obtained at the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., under a cooperative agreement with the NSF on behalf of the Gemini partnership: the National Science Foundation (United States), the Particle Physics and Astronomy Research Council (UK), the National Research Council (Canada), CONICYT (Chile), the Australian Research Council (Australia), CNPq (Brazil) and CONICET (Argentina).Fil: Alvarez Candal, A.. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Jones, D.. University Of London; Reino UnidoFil: Lazzaro, D.. Ministério de Ciencia, Tecnologia e Innovacao. Observatorio Nacional; BrasilFil: Williams, I. P.. University Of London; Reino UnidoFil: Melita, Mario Daniel. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin

    Anti-Hepatitis C Virus Serology in Immune Thrombocytopenia: A Retrospective Analysis in 101 Patients.

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    Hepatitis C virus (HCV), an RNA virus, is known to be the major cause of post-transfusion non-A, non-B hepatitis. HCV can induce several expressions of autoimmunity, including both serological abnormalities and clinical disorders. The relationship between the HCV infection and anti-platelet autoimmunity has been occasionally described, but is still far from well-defined. We retrospectively analysed 101 serum specimens, collected between 1988 and 1994, from patients with immune thrombocytopenia (ITP) for the presence of anti-HCV antibodies. Eighty-seven patients were classified as having idiopathic, and 14 secondary ITP (4 systemic lupus erythematosus, 9 non-Hodgkin's lymphoma and 1 Evan's syndrome). Anti-HCV antibodies were determined by second generation tests (ELISA + RIBA). A specimen was considered positive for HCV antibodies in the presence of ELISA reactivity (sample optical density/cut-off > 1.00) accompanied by RIBA reactivity to at least one HCV specific antigen. 20 sera (20%) were positive, with a prevalence higher in secondary than in idiopathic ITP (43% vs. 16%, p < 0.05). No differences were found between anti-HCV positive and negative patients regarding gender, platelet count, platelet associated immunoglobulins, hepatitis B virus serology and liver enzyme profile. On the contrary, mean age was higher in the HCV positive vs HCV negative ones (58±18SD vs. 44±20yrs, p < 0.01), in keeping with the increasing prevalence of HCV infection with ageing. HCV positive patients, showed a poor response to treatment (platelet count lower than 50,000/μl after conventional medical therapy for immune thrombocytopenia) compared to anti-HCV negative ones, (50% versus 7.3%, p < 0.001). When we excluded patients who were exposed to risk factors for HCV infection after ITP diagnosis and before the serum collection, the prevalence of anti-HCV antibodies was not very different (17.6%) from that found in the series as a whole (19.8%). Our results seem to indicate that HCV infection may play a role in triggering several cases ITP, and moreover might constitute a negative prognostic factor for therapy response

    Ligation of the intersphincteric fistula tract (LIFT) to treat anal fistula: early results from a prospective observational study

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    Ligation of the intersphincteric tract (LIFT), a novel sphincter-saving technique, has been recently described with promising results. Literature data are still scant. In this prospective observational study, we present our experience with this technique

    Choice from Non-Choice: Predicting Consumer Preferences from Blood Oxygenation Level-Dependent Signals Obtained during Passive Viewing

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    Decision-making is often viewed as a two-stage process, where subjective values are first assigned to each option and then the option of the highest value is selected. Converging evidence suggests that these subjective values are represented in the striatum and medial prefrontal cortex (MPFC). A separate line of evidence suggests that activation in the same areas represents the values of rewards even when choice is not required, as in classical conditioning tasks. However, it is unclear whether the same neural mechanism is engaged in both cases. To address this question we measured brain activation with functional magnetic resonance imaging while human subjects passively viewed individual consumer goods. We then sampled activation from predefined regions of interest and used it to predict subsequent choices between the same items made outside of the scanner. Our results show that activation in the striatum and MPFC in the absence of choice predicts subsequent choices, suggesting that these brain areas represent value in a similar manner whether or not choice is required

    Neural Random Utility: Relating Cardinal Neural Observables to Stochastic Choice Behavior

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    We assess whether a cardinal model can be used to relate neural observables to stochastic choice behavior. We develop a general empirical framework for relating any neural observable to choice prediction and propose a means of benchmarking their predictive power. In a previous study, measurements of neural activity were made while subjects considered consumer goods. Here, we find that neural activity predicts choice behavior with the degree of stochasticity in choice related to the cardinality of the measurement. However, we also find that current methods have a significant degree of measurement error which severely limits their inferential and predictive performance

    Stroke Severity Predicted by Aortic Atheroma Detected by Ultra-Fast and Cardiac-Gated Chest Tomography†

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    Background and Purpose: The presence of aortic atherosclerosis is an independent risk factor for secondary stroke. The present study was designed to have an initial exploration of the correlation between the load and extent of aortic atheroma (AA) and initial stroke severity or clinical outcome 3 months after stroke. Methods: Cardiac-gated chest tomography (CGCT) was used to detect and measure AA in patients with acute ischemic stroke as shown by our group in prior prospective studies and this is part four sub-exploratory study of the same cohort. The National Institute of Health Stroke Scale (NIHSS) was used to assess the initial stroke severity, and the modified Rankin Scale (mRS) was used to assess 3-month outcome. Results: Thirty-two patients underwent CGCT for evaluation of AA, and 21 were found to have AA. AA was more prevalent in patient with NIHSS >6 (14/17 versus 7/15, p-value 0.03). Applying the multiple logistic regression and propensity score adjustment (using the propensity of having AA given the baseline features as covariates) showed a non-significant trend that AA is three times more likely to be associated with NIHSS >6 (p = 0.08, OR 3.08, 95% CI 0.94–13.52). There was no evidence of association of AA with 3-month functional outcome (mRS): 11/14 (78.6%) mRS >1 had AA, and 10/18 (55.5%) of those with mRS ≤1 had AA (p = 0.27). Conclusion: In our current study with limited sample number and exploratory nature, the presence of AA on CGCT with acute ischemic stroke patients may be associated with worse neurological deficit at presentation. There was no evidence of association with 3-month functional outcome using the mRS

    Study of Oxidation and Combustion Characteristics of Iron Nanoparticles under Idealized and Enginelike Conditions

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    This document is the Accepted Manuscript version of a Published Work that appeared in final form in Energy Fuels, copyright © American Chemical Society after peer review and technical editing by the publisher.[EN] The present work includes findings from proof-of-principle feasibility studies on iron nanopowder combustion under idealized, enginelike, and real engine conditions. The study was conducted under the scope of recent interest in metallic nanoparticles as alternative fuels for internal combustion engines. More specifically, Fe nanoparticles with different morphologies and average primary particle sizes ranging from 25 to 85 nm were studied with respect to their oxidation characteristics via thermogravimetric analysis as well as in customized shock tube, constant-volume vessel, and compression-ignition (CI) engine configurations. Combusted powder samples were in all cases examined via in situ and ex situ techniques for the identification of combustion products and their morphologies. The findings facilitated the determination of the main phenomena involved during oxidation. The results verified that combustion of Fe nanoparticles in a slightly modified CI engine is feasible, albeit with various technological challenges related to ignition and scavenging that inhibit combustion quality.The authors thank the European Commission for partial funding of this work through the Project “COMETNANO” (FP7-NMP4-SL-2009-229063).Mandilas, C.; Karagiannakis, G.; Konstandopoulos, AG.; Beatrice, C.; Lazzaro, M.; Di Blasio, G.; Molina, S.... (2016). Study of Oxidation and Combustion Characteristics of Iron Nanoparticles under Idealized and Enginelike Conditions. Energy and Fuels. 30(5):4318-4330. https://doi.org/10.1021/acs.energyfuels.6b00121S4318433030
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