834 research outputs found

    An evaluation of the Interactive Software Invocation System (ISIS) for software development applications

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    The Interactive Software Invocation System (ISIS), which allows a user to build, modify, control, and process a total flight software system without direct communications with the host computer, is described. This interactive data management system provides the user with a file manager, text editor, a tool invoker, and an Interactive Programming Language (IPL). The basic file design of ISIS is a five level hierarchical structure. The file manager controls this hierarchical file structure and permits the user to create, to save, to access, and to purge pages of information. The text editor is used to manipulate pages of text to be modified and the tool invoker allows the user to communicate with the host computer through a RUN file created by the user. The IPL is based on PASCAL and contains most of the statements found in a high-level programming language. In order to evaluate the effectiveness of the system as applied to a flight project, the collection of software components required to support the Annular Suspension and Pointing System (ASPS) flight project were integrated using ISIS. The ASPS software system and its integration into ISIS is described

    Interpretive computer simulator for the NASA Standard Spacecraft Computer-2 (NSSC-2)

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    An Interpretive Computer Simulator (ICS) for the NASA Standard Spacecraft Computer-II (NSSC-II) was developed as a code verification and testing tool for the Annular Suspension and Pointing System (ASPS) project. The simulator is written in the higher level language PASCAL and implented on the CDC CYBER series computer system. It is supported by a metal assembler, a linkage loader for the NSSC-II, and a utility library to meet the application requirements. The architectural design of the NSSC-II is that of an IBM System/360 (S/360) and supports all but four instructions of the S/360 standard instruction set. The structural design of the ICS is described with emphasis on the design differences between it and the NSSC-II hardware. The program flow is diagrammed, with the function of each procedure being defined; the instruction implementation is discussed in broad terms; and the instruction timings used in the ICS are listed. An example of the steps required to process an assembly level language program on the ICS is included. The example illustrates the control cards necessary to assemble, load, and execute assembly language code; the sample program to to be executed; the executable load module produced by the loader; and the resulting output produced by the ICS

    Factors related to adolescent drinking in Appalachia

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    Objectives: To examine the relationships among parental monitoring, perceptions of peer drinking, and adolescent alcohol consumption. Methods: Tenth- and 12thgrade students (N=648) in a rural, Appalachian county were surveyed. Results: A binomial logistic regression revealed a composite of those who had perceptions that many peers drank, low parental monitoring, and no biological male guardian in the home were 8.496 times more likely to have ever been drunk. Other characteristics resulted in lower odds. Conclusions: Parental monitoring and perceptions of peer drinking were important predictors of drinking in this rural sample. Prevention efforts in school and at home should address both variables

    Capital Structure Choices and Survival in a Deregulated Environment

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    We examine the impact of capital structure choices for survival in a deregulated industry. Financial leverage in particular has been identified by numerous prior studies as a major determinant of the probability of survival in most industries. In the course of a deregulation, the debt overhang effect stemming from high leverage negatively affects the ability of existing firms to survive when a regulatory shock occurs (Zingales, 1998). Following such a regulatory shock, and consistent with the tradeoff and debt overhang theories of capital structure, firms are more likely to reduce their level of leverage (Ovtchinnikov, 2010). This causes the expected costs of financial distress to rise higher and we can expect a negative association between leverage and survival in a deregulated industry. However, in a highly competitive setting, firms may signal their level of quality by contracting for more debt instead of equity (Ross, 1977). This signaling perspective can therefore induce the existence of a positive association between leverage and survival in a deregulated context. Using a sample of private trucking firms, we test this hypothesis and find a negative association between leverage and survival. In a refined analysis aimed at distinguishing high “quality” versus low “quality” firms, we adopt the “excess capacity” approach of De Vany and Saving (1977). Consistent with our initial findings, we find that the negative association between leverage and survival increases with the level of excess capacity

    Why Are There So Few Female Leaders in Higher Education: A Case of Structure or Agency?

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    A significant gender imbalance remains at executive management level within higher education despite a number of initiatives to increase the number of women in the leadership pipeline and ensure they are better prepared for these roles. This article presents findings from a recent study on the appointment of deputy and pro vice chancellors in pre-1992 English universities that provide fresh insights into why this might be the case. These findings challenge the notion of women’s missing agency - characterised by a lack of confidence or ambition and a tendency to opt out of applying for the top jobs - as an explanation for their continued under-representation. Rather, they highlight the importance of three structural factors associated with the selection process: mobility and external career capital, conservatism, and homosociability. An approach of ‘fixing’ the women is therefore unlikely to be sufficient in redressing the current gender imbalance within university executive management teams

    Low-Intensity Exercise Induces Acute Shifts In Liver And Skeletal Muscle Substrate Metabolism But Not Chronic Adaptations In Tissue Oxidative Capacity

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    Adaptations in hepatic and skeletal muscle substrate metabolism following acute and chronic (6 wk; 5 days/wk; 1 h/day) low-intensity treadmill exercise were tested in healthy male C57BL/6J mice. Low-intensity exercise maximizes lipid utilization; therefore, we hypothesized pathways involved in lipid metabolism would be most robustly affected. Acute exercise nearly depleted liver glycogen immediately postexercise (0 h), whereas hepatic triglyceride (TAG) stores increased in the early stages after exercise (0-3 h). Also, hepatic peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1 alpha) gene expression and fat oxidation (mitochondrial and peroxisomal) increased immediately postexercise (0 h), whereas carbohydrate and amino acid oxidation in liver peaked 24-48 h later. Alternatively, skeletal muscle exhibited a less robust response to acute exercise as stored substrates (glycogen and TAG) remained unchanged, induction of PGC-1 alpha gene expression was delayed (up at 3 h), and mitochondrial substrate oxidation pathways (carbohydrate, amino acid, and lipid) were largely unaltered. Peroxisomal lipid oxidation exhibited the most dynamic changes in skeletal muscle substrate metabolism after acute exercise; however, this response was also delayed (peaked 3-24 h postexercise), and expression of peroxisomal genes remained unaffected. Interestingly, 6 wk of training at a similar intensity limited weight gain, increased muscle glycogen, and reduced TAG accrual in liver and muscle; however, substrate oxidation pathways remained unaltered in both tissues. Collectively, these results suggest changes in substrate metabolism induced by an acute low-intensity exercise bout in healthy mice are more rapid and robust in liver than in skeletal muscle; however, training at a similar intensity for 6 wk is insufficient to induce remodeling of substrate metabolism pathways in either tissue. NEW & NOTEWORTHY Effects of low-intensity exercise on substrate metabolism pathways were tested in liver and skeletal muscle of healthy mice. This is the first study to describe exercise-induced adaptations in peroxisomal lipid metabolism and also reports comprehensive adaptations in mitochondrial substrate metabolism pathways (carbohydrate, lipid, and amino acid). Acute low-intensity exercise induced shifts in mitochondrial and peroxisomal metabolism in both tissues, but training at this intensity did not induce adaptive remodeling of metabolic pathways in healthy mice

    Db / db Mice Exhibit Features of Human Type 2 Diabetes That Are Not Present in Weight-Matched C57BL/6J Mice Fed a Western Diet

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    © 2017 Susan J. Burke et al. To understand features of human obesity and type 2 diabetes mellitus (T2D) that can be recapitulated in the mouse, we compared C57BL/6J mice fed a Western-style diet (WD) to weight-matched genetically obese leptin receptor-deficient mice (db/db). All mice were monitored for changes in body composition, glycemia, and total body mass. To objectively compare diet-induced and genetic models of obesity, tissue analyses were conducted using mice with similar body mass. We found that adipose tissue inflammation was present in both models of obesity. In addition, distinct alterations in metabolic flexibility were evident between WD-fed mice and db/db mice. Circulating insulin levels are elevated in each model of obesity, while glucagon was increased only in the db/db mice. Although both WD-fed and db/db mice exhibited adaptive increases in islet size, the db/db mice also displayed augmented islet expression of the dedifferentiation marker Aldh1a3 and reduced nuclear presence of the transcription factor Nkx6.1. Based on the collective results put forth herein, we conclude that db/db mice capture key features of human T2D that do not occur in WD-fed C57BL/6J mice of comparable body mass

    Evaluation of the public health impacts of traffic congestion: a health risk assessment

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    Background: Traffic congestion is a significant issue in urban areas in the United States and around the world. Previous analyses have estimated the economic costs of congestion, related to fuel and time wasted, but few have quantified the public health impacts or determined how these impacts compare in magnitude to the economic costs. Moreover, the relative magnitudes of economic and public health impacts of congestion would be expected to vary significantly across urban areas, as a function of road infrastructure, population density, and atmospheric conditions influencing pollutant formation, but this variability has not been explored. Methods: In this study, we evaluate the public health impacts of ambient exposures to fine particulate matter (PM2.5) concentrations associated with a business-as-usual scenario of predicted traffic congestion. We evaluate 83 individual urban areas using traffic demand models to estimate the degree of congestion in each area from 2000 to 2030. We link traffic volume and speed data with the MOBILE6 model to characterize emissions of PM2.5 and particle precursors attributable to congestion, and we use a source-receptor matrix to evaluate the impact of these emissions on ambient PM2.5 concentrations. Marginal concentration changes are related to a concentration-response function for mortality, with a value of statistical life approach used to monetize the impacts. Results: We estimate that the monetized value of PM2.5-related mortality attributable to congestion in these 83 cities in 2000 was approximately 31billion(2007dollars),ascomparedwithavalueoftimeandfuelwastedof31 billion (2007 dollars), as compared with a value of time and fuel wasted of 60 billion. In future years, the economic impacts grow (to over 100billionin2030)whilethepublichealthimpactsdecreaseto100 billion in 2030) while the public health impacts decrease to 13 billion in 2020 before increasing to $17 billion in 2030, given increasing population and congestion but lower emissions per vehicle. Across cities and years, the public health impacts range from more than an order of magnitude less to in excess of the economic impacts. Conclusions: Our analyses indicate that the public health impacts of congestion may be significant enough in magnitude, at least in some urban areas, to be considered in future evaluations of the benefits of policies to mitigate congestion
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