1,232 research outputs found

    High Speed Bearing Wear Rate Measurements for Spacecraft Active Thermal Control Fluid Pumps with a Novel Pin on Disk Apparatus

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    A novel pin on disc tribometer was designed and constructed to generate a high-speed, wear coefficient database for hydrodynamic bearings that are typically used in canned motors found in the active thermal control circuits of robotic and inhabited spacecraft. The primary motivation for this work was the premature failure of the active external thermal control pump on the International Space Station in 2010. During the failure investigation of this incident, the root cause was postulated to be high speed wear of the bearings. Although a detailed forensic analysis gave credibility to this theory, the lack of wear coefficient data at relevant conditions prevented validation of this finding. The database generated from the new Extreme Environment Tribometer (EET) enabled a closure calculation within 5% of the observed wear from inspections of the failed hardware. Testing in anhydrous ammonia and surrogate fluid was performed to provide a means for simplified testing in the future and to populate a preliminary database for the design of future active thermal control systems on spacecraft. The EET and test techniques developed for the measurement of high-speed wear coefficients are available to future system designers

    Chronic hemolytic anemia is associated with a new glucose-6-phosphate dehydrogenase in-frame deletion in an older woman

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    Glucose-6-phosphate dehydrogenase (G6PD) deficiency, an X-linked disorder, is usually observed in hemizygote males and very rarely in females. The G6PD class 1 variants, very uncommon, are associated with chronic hemolytic anemia. Here we report a Portuguese woman who suffered in her sixties from a chronic hemolytic anemia due to G6PD deficiency. Molecular studies revealed heterozygosity for an in-frame 18-bp deletion, mapping to exon 10 leading to a deletion of 6 residues, 362-367 (LNERKA), which is a novel G6PD class 1 variant, G6PD Tondela. Two of her three daughters, asymptomatic, with G6PD activity within the normal range, are heterozygous for the same deletion. The patient's leukocyte and reticulocyte mRNA studies revealed an almost exclusive expression of the mutant allele, explaining the chronic hemolytic anemia. Patient whole blood genomic DNA HUMARA assay showed a balanced pattern of X chromosome inactivation (XCI), but granulocyte DNA showed extensive skewing, harboring the mutated allele, implying that in whole blood, lymphocyte DNA, with a very long lifetime, may cover up the current high XCI skewing. This observation indicates that HUMARA assay in women should be assessed in granulocytes and not in total leukocytes

    Bacterial Colitis Increases Susceptibility to Oral Prion Disease

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    Dietary exposure to prion-contaminated materials has caused kuru and variant Creutzfeldt-Jakob disease in humans and transmissible spongiform encephalopathies (TSEs) in cattle, mink, and felines. The epidemiology of dietary prion infections suggests that host genetic modifiers and possibly exogenous cofactors may play a decisive role in determining disease susceptibility. However, few cofactors influencing susceptibility to prion infection have been identified. In the present study,we investigated whether colitis might represent one such cofactor.Were port that moderate colitis caused by an attenuated Salmonella strain more than doubles the susceptibility of mice to oral prion infection and modestly accelerates the development of disease after prion challenge. The prion protein was up-regulated in intestines and mesenteric lymph nodes of mice with colitis, providing a possible mechanism for the effect of colitis on the pathogenesis of prion disease. Therefore, moderate intestinal inflammation at the time of prion exposure may constitute one of the elusive risk factors underlying the development of TS

    Surfactant Protein D, a Marker of Lung Innate Immunity, Is Positively Associated With Insulin Sensitivity

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    Impaired lung function and innate immunity have both attracted growing interest as a potentially novel risk factor for glucose intolerance, insulin resistance, and type 2 diabetes. We aimed to evaluate whether surfactant protein D (SP-D), a lung-derived innate immune protein, was behind these associations

    Renal structure and hypertension in autosomal dominant polycystic kidney disease

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    Renal structure and hypertension in autosomal dominant polycystic kidney disease. Hypertension has been reported to occur in 50 to 75 percent of subjects with autosomal dominant polycystic kidney disease (ADPKD) prior to the onset of marked renal insufficiency but concurrent with cystic deformation of the renal parenchyma. The present study was undertaken to examine whether the renal structural abnormalities are greater in hypertensive (HBP) versus normotensive (NBP) male and female patients with ADPKD who were matched within gender groups for age, body surface area, serum creatinine concentration (males HBP 1.2 ± 0.02 vs. NBP 1.1 ± 0.03 mg/dl, NS; females HBP 0.9 ± 0.03 vs. NBP 0.9 ± 0.02 mg/dl, NS) and creatinine clearance (males HBP 100 ± 3 vs. NBP 108 ± 3 ml/min/1.73 m2, NS; females HBP 97 ± 3 vs. NBP 96 ± 2 ml/min/1.73 m2, NS). Renal volume was significantly greater in the HBP compared to the NBP group (males HBP 624 ± 47 vs. NBP 390 ± 43 cm3, P < 0.0005; females HBP 466 ± 32 vs. NBP 338 ± 24 cm3, P < 0.002). Since increased renal volume is due to increased cysts, the results indicate that the early high incidence of hypertension in ADPKD correlates with the renal structural abnormalities in this disorder

    Hyper-parameter optimization for latent spaces

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    We present an online optimization method for time-evolving data streams that can automatically adapt the hyper-parameters of an embedding model. More specifically, we employ the Nelder-Mead algorithm, which uses a set of heuristics to produce and exploit several potentially good configurations, from which the best one is selected and deployed. This step is repeated whenever the distribution of the data is changing. We evaluate our approach on streams of real-world as well as synthetic data, wherethe latter is generated in such way that its characteristics change over time (concept drift). Overall, we achieve good performance in terms of accuracy compared to state-of-the-art AutoML techniques.Algorithms and the Foundations of Software technolog
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