4,228 research outputs found

    Avionics for a Small Satellite

    Get PDF
    This paper discusses a small. seven and a half (7.5) inch diameter. satellite that NASA-JSC is developing as a technology demonstrator for an astronaut assistant free flyer. The Free Flyer is designed to off load flight crew work load by performing inspections of the exterior of Space Shuttle or International Space Station. The Free Flyer is designed to be operated by the flight crew thereby reducing the number of Extra Vehicle Activities (EVA) or by an astronaut on the ground further reducing crew work load. The paper focuses on the design constraint of a small satellite and the technology approach used to achieve the set of high performance requirements specified for the Free Flyer. Particular attention is paid to the processor card as it is the heart and system integration point of the Free Flyer

    The vicinal difluoro motif : the synthesis and conformation of erythro- and threo-diastereoisomers of 1,2-difluorodiphenylethanes, 2,3-difluorosuccinic acids and their derivatives

    Get PDF
    Background: It is well established that vicinal fluorines (RCHF-CHFR) prefer to adopt a gauche rather than an anti conformation when placed along aliphatic chains. This has been particularly recognised for 1,2-difluoroethane and extends to 2,3-difluorobutane and longer alkyl chains. It follows in these latter cases that if erythro and threo vicinal difluorinated stereoisomers are compared, they will adopt different overall conformations if the fluorines prefer to be gauche in each case. This concept is explored in this paper with erythro- and threo- diastereoisomers of 2,3-difluorosuccinates. Results: A synthetic route to 2,3-difluorosuccinates has been developed through erythro- and threo- 1,2-difluoro-1,2-diphenylethane which involved the oxidation of the aryl rings to generate the corresponding 2,3- difluorosuccinic acids. Ester and amide derivatives of the erythro- and threo- 2,3-difluorosuccinic acids were then prepared. The solid and solution state conformation of these compounds was assessed by X-ray crystallography and NMR. Ab initio calculations were also carried out to model the conformation of erythro- and threo- 1,2-difluoro-1,2-diphenylethane as these differed from the 2,3-difluorosuccinates. Conclusion: In general the overall chain conformations of the 2,3-difluorosuccinates diastereoisomers were found to be influenced by the fluorine gauche effect. The study highlights the prospects of utilising the vicinal difluorine motif (RCHF-CHFR) as a tool for influencing the conformation of performance organic molecules and particularly tuning conformation by selecting specific diastereoisomers (erythro or threo).Publisher PDFPeer reviewe

    Is the Stack Distance Between Test Case and Method Correlated With Test Effectiveness?

    Full text link
    Mutation testing is a means to assess the effectiveness of a test suite and its outcome is considered more meaningful than code coverage metrics. However, despite several optimizations, mutation testing requires a significant computational effort and has not been widely adopted in industry. Therefore, we study in this paper whether test effectiveness can be approximated using a more light-weight approach. We hypothesize that a test case is more likely to detect faults in methods that are close to the test case on the call stack than in methods that the test case accesses indirectly through many other methods. Based on this hypothesis, we propose the minimal stack distance between test case and method as a new test measure, which expresses how close any test case comes to a given method, and study its correlation with test effectiveness. We conducted an empirical study with 21 open-source projects, which comprise in total 1.8 million LOC, and show that a correlation exists between stack distance and test effectiveness. The correlation reaches a strength up to 0.58. We further show that a classifier using the minimal stack distance along with additional easily computable measures can predict the mutation testing result of a method with 92.9% precision and 93.4% recall. Hence, such a classifier can be taken into consideration as a light-weight alternative to mutation testing or as a preceding, less costly step to that.Comment: EASE 201

    Landowner willingness to engage in long-term timber leases in West Virginia, USA

    Get PDF
    As global competition increases for wood-based products, the need for more efficient supply chains becomes increasingly important. In the forest products sector, these supply chains involve individuals and firms ranging from private forestland owners with standing timber to factories producing final finished products. Under the assumption that ‘transparent’ supply chains are beneficial to members within the supply chain, the authors are investigating how this transparency can be increased and what benefits might accrue to private forest owners who are associated with a specific supply chain under a long-term agreement. In recent years, hunting lease agreements between family forest owners and various organized hunt clubs or individuals have become commonplace in the Appalachian mountains of West Virginia. Can long-term timber leases become a new opportunity for landowners, forestry professionals, and wood-based industries? This paper describes a survey of private forestland owners in West Virginia that investigated the perceived concerns, benefits and barriers landowners have with regard to entering long-term timber leases with forestry professionals and timber firms

    Discovering Patient Phenotypes Using Generalized Low Rank Models

    Get PDF
    The practice of medicine is predicated on discovering commonalities or distinguishing characteristics among patients to inform corresponding treatment. Given a patient grouping (hereafter referred to as a p henotype ), clinicians can implement a treatment pathway accounting for the underlying cause of disease in that phenotype. Traditionally, phenotypes have been discovered by intuition, experience in practice, and advancements in basic science, but these approaches are often heuristic, labor intensive, and can take decades to produce actionable knowledge. Although our understanding of disease has progressed substantially in the past century, there are still important domains in which our phenotypes are murky, such as in behavioral health or in hospital settings. To accelerate phenotype discovery, researchers have used machine learning to find patterns in electronic health records, but have often been thwarted by missing data, sparsity, and data heterogeneity. In this study, we use a flexible framework called Generalized Low Rank Modeling (GLRM) to overcome these barriers and discover phenotypes in two sources of patient data. First, we analyze data from the 2010 Healthcare Cost and Utilization Project National Inpatient Sample (NIS), which contains upwards of 8 million hospitalization records consisting of administrative codes and demographic information. Second, we analyze a small (N=1746), local dataset documenting the clinical progression of autism spectrum disorder patients using granular features from the electronic health record, including text from physician notes. We demonstrate that low rank modeling successfully captures known and putative phenotypes in these vastly different datasets

    Inhibition of HIF-1 alpha by PX-478 enhances the anti-tumor effect of gemcitabine by inducing immunogenic cell death in pancreatic ductal adenocarcinoma

    Get PDF
    This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

    Visualizing and Preparing Census Data with Tableau

    Get PDF
    Are you a user of Tableau Public but struggle to integrate Census downloads into your visualizations? If so, this workshop, intended for users just starting to integrate Tableau into their Census Data visualizations, might be right for you. Throughout this experience, you will learn several tips and tricks on how to format and prepare census data for an easier experience in the Tableau Public environment

    Datasets and Tools that Help Measure America

    Get PDF
    This session will provide an overview of datasets and web tools for the most widely used data accessed on census. gov. This session will provide a live demonstration of where to find enhancements to existing tools and new tools that are available on the public access site of census.gov based on data user feedback the Census Bureau receives at an ongoing basis

    Updates to Data Access at the Census Bureau

    Get PDF
    This session will provide an overview of updates and new tools for the most widely used data accessed on census.gov. This session will provide a live demonstration of where to find enhancements to existing tools and new tools that are available on the public access site of census.gov based on data user feedback the Census Bureau receives at an ongoing basis. We will also look at the future of data.census, currently in beta, for users to experience and provide feedback during development

    Demonstration of Census Data Tools: American FactFinder

    Get PDF
    As a Data Dissemination Specialist, US Commerce Department, Bureau of Census, David is one of 26 in a Bureau of 15,000, engaging citizens and connecting them with Census business, economic, trade and demographic data. He teaches workshops and presentations to data users on how to use Census data tools to mine government data. This high quality data supports business plans, grant opportunities and critical discussion making
    corecore