Orbital assembly and maintenance study

The requirements, conceptual design, tradeoffs, procedures, and techniques for orbital assembly of the support structure of the microwave power transmission system and the radio astronomy telescope are described. Thermal and stress analyses, packaging, alignment, and subsystems requirements are included along with manned vs. automated and transportation tradeoffs. Technical and operational concepts for the manned and automated maintenance of satellites were investigated and further developed results are presented

Orbital assembly and maintenance study. Executive summary

A sound, practical approach for the assembly and maintenance of very large structures in space is presented. The methods and approaches for assembling two large structures are examined. The maintenance objectives include the investigation of methods to maintain five geosynchronous satellites. The two assembly examples are a 200-meter-diameter radio astronomy telescope and a 1,000-meter-diameter microwave power transmission system. The radio astronomy telescope operates at an 8,000-mile altitude and receives RF signals from space. The microwave power transmission system is part of a solar power satellite that will be used to transmit converted solar energy to microwave ground receivers. Illustrations are included

Regression analysis of the results of examinations of students in probability theory

In this paper, is carried a study of the dependence of the results of tests with the help of linear and nonlinear regression analysis. As a result of an earlier statistical analysis with the same data, was found the relationship between them

Species-dependent responses of crop plants to polystyrene microplastics

Abstract: Only recently there has been a strong focus on the impacts of microplastics on terrestrial crop plants. This study aims to examine and compare the effects of microplastics on two monocotyledonous (barley, Hordeum vulgare and wheat, Triticum aestivum), and two dicotyledonous (carrot, Daucus carota and lettuce, Lactuca sativa) plant species through two complimentary experiments. First, we investigated the effects of low, medium, and high (103, 105, 107 particles per mL) concentrations of 500 nm polystyrene microplastics (PS-MPs) on seed germination and early development. We found species-dependent effects on the early development, with microplastics only significantly affecting lettuce and carrot. When acutely exposed during germination, PS-MPs significantly delayed the germination of lettuce by 24%, as well as promoted the shoot growth of carrot by 71% and decreased its biomass by 26%. No effect was recorded on monocot species. Secondly, we performed a chronic (21 d) hydroponic experiment on lettuce and wheat. We observed that PS-MPs significantly reduced the shoot growth of lettuce by up to 35% and increased its biomass by up to 64%, while no record was reported on wheat. In addition, stress level indicators and defence mechanisms were significantly up-regulated in both lettuce and wheat seedlings. Overall, this study shows that PS-MPs affect plant development: impacts were recorded on both germination and growth for dicots, and responses identified by biochemical markers of stress were increased in both lettuce and wheat. This highlights species-dependent effects as the four crops were grown under identical conditions to allow direct comparison. For future research, our study emphasizes the need to focus on crop specific effects, while also working towards knowledge of plastic-induced impacts at environmentally relevant conditions

ACE I/D polymorphism is associated with mortality in a cohort study of patients starting with dialysis

ACE I/D polymorphism is associated with mortality in a cohort study of patients starting with dialysis.BackgroundIn dialysis patients, only a few follow-up studies have addressed the relationship between the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene and mortality, but the available data are contradictory.MethodsA cohort of 453 consecutive patients starting dialysis between January 1999 and January 2002 and participating in a Dutch multicenter prospective study was examined. Patients who died within 3 months after the start of dialysis were excluded. Patients were followed until date of death or censoring in November 2003.ResultsThe ACE II, ID, and DD genotype frequencies were 24.3% (N = 110), 50.1% (N = 227), and 25.6% (N = 116). Besides a slightly higher number of Caucasians in the DD group, all other patient characteristics of the 3 ACE groups were similar at the start of dialysis. After adjustment for age, comorbidity, and ethnic background, patients with the ID and DD genotype showed an increased hazard ratio (HR) for all-cause mortality of 1.55 (95% CI 1.00-2.42) and 2.30 (95% CI 1.41-3.75), compared to patients with the II genotype. Slightly lower HRs were found for cardiovascular mortality. All groups of primary kidney disease showed a 2- to 3-fold increased adjusted HR for DD.ConclusionThe DD genotype identifies dialysis patients at an increased risk for mortality

Coordinatively Saturated Tris(oxazolinyl)borato Zinc Hydride-Catalyzed Cross Dehydrocoupling of Silanes and Alcohols

The four-coordinate zinc compound ToMZnH (1, ToM = tris(4,4-dimethyl-2-oxazolinyl)phenylborate) catalyzes selective alcoholysis of substituted hydrosilanes. The catalytic reaction of PhMeSiH2 and aliphatic alcohols favors the monodehydrocoupled product PhMeHSi–OR. With the aryl alcohol 3,5-C6H3Me2OH, the selectivity for mono(aryloxy)hydrosilane PhMeHSiOC6H3Me2 and bis(aryloxy)silane PhMeSi(OC6H3Me2)2 is controlled by relative reagent concentrations. Reactions of secondary organosilanes and diols provide cyclic bis(oxo)silacycloalkanes in high yield. The empirical rate law for the ToMZnH-catalyzed reaction of 3,5-dimethylphenol and PhMeSiH2 is −d[PhMeSiH2]/dt = k′obs[ToMZnH]1[3,5-C6H3Me2OH]0[PhMeSiH2]1 (determined at 96 °C) which indicates that Si–O bond formation is turnover-limiting in the presence of excess phenol

"Come Together!": Interactions of Language Networks and Multilingual Communities on Twitter

Emerging tools and methodologies are providing insight into the factors that promote the propagation of information in online social networks following significant activities, such as high-profile international social or societal events. This paper presents an extensible approach for analysing how different language communities engage and interact on the social networking platform Twitter via an analysis of the Eurovision Song Contest held in Stockholm, Sweden, in May 2016. By utilising language information from user profiles (N=1,226,959) and status updates (N=7,926,746) to identify and categorise communities, our approach is able to categorise these interactions, as well as construct network graphs to provide further insight on these multilingual communities. The results show that multilingualism is positively correlated with activity whilst negatively correlated with posting in the user’s own language

Globotriaosylsphingosine Accumulation and Not Alpha-Galactosidase-A Deficiency Causes Endothelial Dysfunction in Fabry Disease

BACKGROUND: Fabry disease (FD) is caused by a deficiency of the lysosomal enzyme alpha-galactosidase A (GLA) resulting in the accumulation of globotriaosylsphingosine (Gb3) in a variety of tissues. While GLA deficiency was always considered as the fulcrum of the disease, recent attention shifted towards studying the mechanisms through which Gb3 accumulation in vascular cells leads to endothelial dysfunction and eventually multiorgan failure. In addition to the well-described macrovascular disease, FD is also characterized by abnormalities of microvascular function, which have been demonstrated by measurements of myocardial blood flow and coronary flow reserve. To date, the relative importance of Gb3 accumulation versus GLA deficiency in causing endothelial dysfunction is not fully understood; furthermore, its differential effects on cardiac micro- and macrovascular endothelial cells are not known. METHODS AND RESULTS: In order to assess the effects of Gb3 accumulation versus GLA deficiency, human macro- and microvascular cardiac endothelial cells (ECs) were incubated with Gb3 or silenced by siRNA to GLA. Gb3 loading caused deregulation of several key endothelial pathways such as eNOS, iNOS, COX-1 and COX-2, while GLA silencing showed no effects. Cardiac microvascular ECs showed a greater susceptibility to Gb3 loading as compared to macrovascular ECs. CONCLUSIONS: Deregulation of key endothelial pathways as observed in FD vasculopathy is likely caused by intracellular Gb3 accumulation rather than deficiency of GLA. Human microvascular ECs, as opposed to macrovascular ECs, seem to be affected earlier and more severely by Gb3 accumulation and this notion may prove fundamental for future progresses in early diagnosis and management of FD patients