788 research outputs found

    Emission mechanism of GeV-quiet soft gamma-ray pulsars: a case for peculiar geometry?

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    High-energy emission of the first millisecond pulsar

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    HIGH-ENERGY EMISSIONS FROM THE GAMMA-RAY BINARY LS 5039

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    The role of transesophageal echocardiography in the diagnosis and management of children and young adults with valvar diseases of the left heart

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    Summary The role of transesophageal echocardiography in the diagnosis and management of left-sided cardiac valvar disease in children and young adults was assessed in terms of whether additional information (over transthoracic echocardiography) could be obtained, and whether the added information contributed to the better management of the patients. Between January 1991 to August 1992, 27 consecutive patients were studied. Their age ranged from 2.5 to 20 years (mean 12.7), with body weights ranging between 12 and 60 kg (mean 35.6). Twelve of the children suffered from atrioventricular valvar disease, 13 had predominant aortic valvar lesions and two had mixed valvar pathologies. Additional information was obtained by transesophageal over that of transthoracic echocardiography in 18 children (67%). Transesophageal echocardiography clarified the etiologies or mechanism of valvar regurgitation in eight and seven children with atrioventricular and aortic pathologies, respectively. The technique correctly diagnosed severe mitral regurgitation underestimated by conventional technique, detected a missed eccentric aortic regurgitant jet and convincingly excluded bacterial vegetations in one case each. The investigation contributed to the better management of three children (11%) by providing information that allowed the appropriate choice of therapy. Transesophageal echocardiography, therefore, is a useful technique for the diagnosis and management of valvar disease of the left heart in children and young adults.published_or_final_versio

    Fermi-lat Detection Of Pulsed Gamma-rays Above 50 Gev From The Vela Pulsar

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    Three-Dimensional Spectral-Domain Optical Coherence Tomography Data Analysis for Glaucoma Detection

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    Purpose: To develop a new three-dimensional (3D) spectral-domain optical coherence tomography (SD-OCT) data analysis method using a machine learning technique based on variable-size super pixel segmentation that efficiently utilizes full 3D dataset to improve the discrimination between early glaucomatous and healthy eyes. Methods: 192 eyes of 96 subjects (44 healthy, 59 glaucoma suspect and 89 glaucomatous eyes) were scanned with SD-OCT. Each SD-OCT cube dataset was first converted into 2D feature map based on retinal nerve fiber layer (RNFL) segmentation and then divided into various number of super pixels. Unlike the conventional super pixel having a fixed number of points, this newly developed variable-size super pixel is defined as a cluster of homogeneous adjacent pixels with variable size, shape and number. Features of super pixel map were extracted and used as inputs to machine classifier (LogitBoost adaptive boosting) to automatically identify diseased eyes. For discriminating performance assessment, area under the curve (AUC) of the receiver operating characteristics of the machine classifier outputs were compared with the conventional circumpapillary RNFL (cpRNFL) thickness measurements. Results: The super pixel analysis showed statistically significantly higher AUC than the cpRNFL (0.855 vs. 0.707, respectively, p = 0.031, Jackknife test) when glaucoma suspects were discriminated from healthy, while no significant difference was found when confirmed glaucoma eyes were discriminated from healthy eyes. Conclusions: A novel 3D OCT analysis technique performed at least as well as the cpRNFL in glaucoma discrimination and even better at glaucoma suspect discrimination. This new method has the potential to improve early detection of glaucomatous damage. © 2013 Xu et al

    Large sulfur isotope fractionations in Martian sediments at Gale crater

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    Variability in the sulfur isotopic composition in sediments can reflect atmospheric, geologic and biological processes. Evidence for ancient fluvio-lacustrine environments at Gale crater on Mars and a lack of efficient crustal recycling mechanisms on the planet suggests a surface environment that was once warm enough to allow the presence of liquid water, at least for discrete periods of time, and implies a greenhouse effect that may have been influenced by sulfur-bearing volcanic gases. Here we report in situ analyses of the sulfur isotopic compositions of SO2 volatilized from ten sediment samples acquired by NASA’s Curiosity rover along a 13 km traverse of Gale crater. We find large variations in sulfur isotopic composition that exceed those measured for Martian meteorites and show both depletion and enrichment in 34S. Measured values of δ34S range from −47 ± 14‰ to 28 ± 7‰, similar to the range typical of terrestrial environments. Although limited geochronological constraints on the stratigraphy traversed by Curiosity are available, we propose that the observed sulfur isotopic signatures at Gale crater can be explained by equilibrium fractionation between sulfate and sulfide in an impact-driven hydrothermal system and atmospheric processing of sulfur-bearing gases during transient warm periods

    HLA alleles associated with asparaginase hypersensitivity in Chinese children

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    Asparaginase is an important drug to treat childhood haematological malignancies. Data on the association between human leukocyte antigens (HLA) and asparaginase hypersensitivity among Chinese are lacking. We conducted a retrospective study to identify HLA alleles associated with asparaginase hypersensitivity among Chinese children with acute lymphoblastic leukaemia (ALL), mixed phenotype leukaemia and non-Hodgkin lymphoma (NHL), who received asparaginases with HLA typing performed between 2009 and 2019. 107 Chinese patients were analysed. 66.3% (71/107) developed hypersensitivity to at least one of the asparaginases. HLA-B*46:01 (OR 3.8, 95% CI 1.4-10.1, p < 0.01) and DRB1*09:01 (OR 4.3, 95% CI 1.6-11.4, p < 0.01) were significantly associated with L-asparaginase hypersensitivities, which remained significant after adjustment for age, gender and B cell ALL [HLA-B*46:01 (adjusted OR 3.5, 95% 1.3-10.5, p = 0.02) and DRB1*09:01 (OR 4.4, 95% CI 1.6-13.3, p < 0.01)]
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