1,958 research outputs found

    Nuclear rocket propulsion. NASA plans and progress, FY 1991

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    NASA has initiated planning for a technology development project for nuclear rocket propulsion systems for space explorer initiative (SEI) human and robotic missions to the moon and Mars. An interagency project is underway that includes the Department of Energy National Laboratories for nuclear technology development. The activities of the project planning team in FY 1990 and 1991 are summarized. The progress to date is discussed, and the project plan is reviewed. Critical technology issues were identified and include: (1) nuclear fuel temperature, life, and reliability; (2) nuclear system ground test; (3) safety; (4) autonomous system operation and health monitoring; and (5) minimum mass and high specific impulse

    Changes In Fish Communties Throughout The Buck Creek Watershed In Relation To Land Use

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    Physical alterations of terrestrial habitat surrounding aquatic systems lead to increases in runoff, sedimentation, and nutrient inputs. Tracking changes in fish communities can provide information regarding degradation of water quality and the biotic integrity of freshwater systems. Changes in fish communities, and specifically declines in Buck Darter (Etheostoma nebra) populations, have been observed throughout the Buck Creek watershed since the 1980’s. Thus, goals of this project were to determine if shifts in fish community composition (eg., sensitive to less sensitive families, intolerant to tolerant species, and changes in feeding groups) and extirpation of the Buck Darter in 6 of 8 historically populated sub-watersheds are related to changes in land use/land cover (LULC) proportions from 1983, 2010, and 2020. LULC proportions were determined using GIS at a local and sub-watershed scale to discern (1) changes in fish communities relative to LULC between 1983 and 2012, (2) sub-watersheds for reintroduction of E. nebra based on historic LULC, and (3) streams in need of restoration relative to E. nebra conservation. A detrended correspondence analysis (DCA) was used to determine relationships between LULC and fish communities between years and spatial scales. A principal component analysis (PCA) of 1983 and 2020 LULC proportions was used to identify sub-watersheds for the reintroduction of E. nebra based on the least change from 1983 and stream buffers in need of restoration based on. Agriculture/pasture dominated LULC proportions in 1983, 2010, and 2020 at the watershed level. Intolerant fish species, invertivores, omnivores, herbivores and darter species distributions decreased in sub-watersheds dominated by agriculture/pasture LULC (\u3e50%). Centrarchids occurred in sub-watersheds in 2012 where they were absent in 1983 and increased in abundance in streams that gained proportions of development. LULC proportions at the buffer level demonstrated riparian reforestation efforts occurring throughout the Buck Creek watershed from 1983-2010. With forest proportions higher in Crab Orchard Creek and Gilmore Creek in 2010, intolerant, invertivore, and darter species proportions still decreased. This suggests that changes in fish communities within the Buck Creek watershed are operating at the watershed scale. Results from a PCA demonstrated that Gilmore Creek and Crab Orchard Creek showed the least LULC change, and Brushy Creek remained associated with agriculture/pasture in 2020. With little change in LULC proportions observed between years, disturbance of the Buck Creek watershed occurred prior to 1983, with fish communities exhibiting a delayed response. Further reforestation of riparian buffers will reduce inputs of sediment and reduce inputs of organic and inorganic nutrients into tributaries of the Buck Creek watershed

    Estimation of the Economic Benefit of Air Jamaica to Jamaica between 1995 and 2004

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    In this study, we estimate the economic benefit of Air Jamaica to Jamaica between 1995 and 2004. Specifically, we determine the economic benefit of Air Jamaica by estimating the economic contribution of air transportation for the case where Air Jamaica does not exist and then subtracting this value from the economic contribution of air transportation for the case where Air Jamaica does exist. Thus the value we determine is the incremental contribution of Air Jamaica to the Jamaican economy, i.e. the benefit that can only be attributed to the presence of Air Jamaica. Although there are many different ways in which airlines contribute to socioeconomic growth, only two of these mechanisms are explored in this study: 1) the portion of airline revenues that remain in Jamaica by virtue of the wages that are paid to residents of Jamaica, and the goods and services that are purchased from companies in Jamaica; 2) the expenditures of foreign visitors. Therefore, this study represents a conservative estimate of the benefit of Air Jamaica to the Jamaican economy. The results of our analysis indicate that the economic benefit of Air Jamaica to Jamaica between 1995 and 2004 economy was US5.491 Billion of which US1.830BillionwasadirectincrementalcontributiontotheeconomyandUS1.830 Billion was a direct incremental contribution to the economy and US3.661 Billion is the corresponding indirect incremental contribution

    Nonclassic lipoid congenital adrenal hyperplasia masquerading as familial glucocorticoid deficiency

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    Context: Familial glucocorticoid deficiency (FGD) is an autosomal recessive disorder resulting from resistance to the action of ACTH on the adrenal cortex. Affected individuals are deficient in cortisol and, if untreated, are likely to succumb to hypoglycemia and/or overwhelming infection. Mutations of the ACTH receptor (MC2R) and the melanocortin 2 receptor accessory protein (MRAP), FGD types 1 and 2 respectively, account for approximately 45% of cases. Objective: A locus on chromosome 8 has previously been linked to the disease in three families, but no underlying gene defect has to date been identified. Design: The study design comprised single-nucleotide polymorphism genotyping and mutation detection. Setting: The study was conducted at secondary and tertiary referral centers. Patients: Eighty probands from families referred for investigation of the genetic cause of FGD participated in the study. Interventions: There were no interventions. Results: Analysis by single-nucleotide polymorphism array of the genotype of one individual with FGD previously linked to chromosome 8 revealed a large region of homozygosity encompassing the steroidogenic acute regulatory protein gene, STAR. We identified homozygous STAR mutations in this patient and his affected siblings. Screening of our total FGD patient cohort revealed homozygous STAR mutations in a further nine individuals from four other families. Conclusions: Mutations in STAR usually cause lipoid congenital adrenal hyperplasia, a disorder characterized by both gonadal and adrenal steroid deficiency. Our results demonstrate that certain mutations in STAR (R192C and the previously reported R188C) can present with a phenotype indistinguishable from that seen in FGD

    Ballroom Music Spillover into a Beluga Whale Aquarium Exhibit

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    It is not uncommon for modern aquaria to be built with special entertainment areas. There are no known measurements of sound spillover from such entertainment areas into underwater animal exhibits. Entertainment organizations typically prefer to play music for events at 95 and 100 dBA in a ballroom at Georgia Aquarium. Concern over the potential effects of the music and noise on animals in adjacent exhibits inspired an initial project to monitor and compare sound levels in the adjacent underwater exhibits against the typical in-air sound levels of the ballroom. Measured underwater noise levels were compared to modeled levels based on finite element analysis and plane wave transmission loss calculations through the acrylic viewing window. Results were compared with the model to determine how, if at all, the ambient noise level in the Cold Water Quest exhibit changed as a result of music played in the ballroom

    Lessons learned from 104 years of mobile observatories [poster]

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    Poster session IN13B-1211 presented 10 December 2007 at the AGU Fall Meeting, 10–14 December 2007, San Francisco, CA, USAAs the oceanographic community ventures into a new era of integrated observatories, it may be helpful to look back on the era of "mobile observatories" to see what Cyberinfrastructure lessons might be learned. For example, SIO has been operating research vessels for 104 years, supporting a wide range of disciplines: marine geology and geophysics, physical oceanography, geochemistry, biology, seismology, ecology, fisheries, and acoustics. In the last 6 years progress has been made with diverse data types, formats and media, resulting in a fully-searchable online SIOExplorer Digital Library of more than 800 cruises (http://SIOExplorer.ucsd.edu). Public access to SIOExplorer is considerable, with 795,351 files (206 GB) downloaded last year. During the last 3 years the efforts have been extended to WHOI, with a "Multi-Institution Testbed for Scalable Digital Archiving" funded by the Library of Congress and NSF (IIS 0455998). The project has created a prototype digital library of data from both institutions, including cruises, Alvin submersible dives, and ROVs. In the process, the team encountered technical and cultural issues that will be facing the observatory community in the near future. Technological Lessons Learned: Shipboard data from multiple institutions are extraordinarily diverse, and provide a good training ground for observatories. Data are gathered from a wide range of authorities, laboratories, servers and media, with little documentation. Conflicting versions exist, generated by alternative processes. Domain- and institution-specific issues were addressed during initial staging. Data files were categorized and metadata harvested with automated procedures. With our second-generation approach to staging, we achieve higher levels of automation with greater use of controlled vocabularies. Database and XML- based procedures deal with the diversity of raw metadata values and map them to agreed-upon standard values, in collaboration with the Marine Metadata Interoperability (MMI) community. All objects are tagged with an expert level, thus serving an educational audience, as well as research users. After staging, publication into the digital library is completely automated. The technical challenges have been largely overcome, thanks to a scalable, federated digital library architecture from the San Diego Supercomputer Center, implemented at SIO, WHOI and other sites. The metadata design is flexible, supporting modular blocks of metadata tailored to the needs of instruments, samples, documents, derived products, cruises or dives, as appropriate. Controlled metadata vocabularies, with content and definitions negotiated by all parties, are critical. Metadata may be mapped to required external standards and formats, as needed. Cultural Lessons Learned: The cultural challenges have been more formidable than expected. They became most apparent during attempts to categorize and stage digital data objects across two institutions, each with their own naming conventions and practices, generally undocumented, and evolving across decades. Whether the questions concerned data ownership, collection techniques, data diversity or institutional practices, the solution involved a joint discussion with scientists, data managers, technicians and archivists, working together. Because metadata discussions go on endlessly, significant benefit comes from dictionaries with definitions of all community-authorized metadata values.Funding provided by the Library of Congress and NSF (IIS 0455998

    Proposed Lunar Measurements of rr-Process Radioisotopes to Distinguish Origin of Deep-sea 244Pu

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    244Pu has recently been discovered in deep-sea deposits spanning the past 10 Myr, a period that includes two 60Fe pulses from nearby supernovae. 244Pu is among the heaviest rr-process products, and we consider whether it was created in the supernovae, which is disfavored by nucleosynthesis simulations, or in an earlier kilonova event that seeded 244Pu in the nearby interstellar medium that was subsequently swept up by the supernova debris. We discuss how these possibilities can be probed by measuring 244Pu and other rr-process radioisotopes such as 129I and 182Hf, both in lunar regolith samples returned to Earth by missions such as Chang'e and Artemis, and in deep-sea deposits.Comment: Extensive rewrite of v1 with added emphasis of lunar sample return missions, including Artemis and Chang'e. 11 pages, 4 figures, 2 tabl

    David Quentin Bowen: A memorial

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    The Quaternary community lost a giant and a leader on October 5, 2020, when David Quentin Bowen, known to many as “DQ” and founding editor of Quaternary Science Reviews, passed away in Cardiff. Born on February 14, 1938 in Llanelli, SouthWales, he received his PhD at University College London. David’s 50 years of contributions to our science cannot be adequately summarized in a brief memorial but past, present, and future generations of Quaternary scientists will long remember his landmark achievements in publishing, his scientific contributions, and his personal and professional class in all his endeavors

    Use of Coronary Computed Tomographic Angiography to guide management of patients with coronary disease

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    Background In a prospective, multicenter, randomized controlled trial, 4,146 patients were randomized to receive standard care or standard care plus coronary computed tomography angiography (CCTA). Objectives The purpose of this study was to explore the consequences of CCTA-assisted diagnosis on invasive coronary angiography, preventive treatments, and clinical outcomes. Methods In post hoc analyses, we assessed changes in invasive coronary angiography, preventive treatments, and clinical outcomes using national electronic health records. Results Despite similar overall rates (409 vs. 401; p = 0.451), invasive angiography was less likely to demonstrate normal coronary arteries (20 vs. 56; hazard ratios [HRs]: 0.39 [95% confidence interval (CI): 0.23 to 0.68]; p < 0.001) but more likely to show obstructive coronary artery disease (283 vs. 230; HR: 1.29 [95% CI: 1.08 to 1.55]; p = 0.005) in those allocated to CCTA. More preventive therapies (283 vs. 74; HR: 4.03 [95% CI: 3.12 to 5.20]; p < 0.001) were initiated after CCTA, with each drug commencing at a median of 48 to 52 days after clinic attendance. From the median time for preventive therapy initiation (50 days), fatal and nonfatal myocardial infarction was halved in patients allocated to CCTA compared with those assigned to standard care (17 vs. 34; HR: 0.50 [95% CI: 0.28 to 0.88]; p = 0.020). Cumulative 6-month costs were slightly higher with CCTA: difference 462(95462 (95% CI: 303 to $621). Conclusions In patients with suspected angina due to coronary heart disease, CCTA leads to more appropriate use of invasive angiography and alterations in preventive therapies that were associated with a halving of fatal and non-fatal myocardial infarction. (Scottish COmputed Tomography of the HEART Trial [SCOT-HEART]; NCT01149590

    Development of the Jackson Heart Study Coordinating Center

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    The public health burden caused by cardiovascular disease (CVD) continues to adversely affect individuals in terms of cost, life expectancy, medical, pharmaceutical and hospital care. This burden has been excessive in the case of African Americans. The objective of this paper is to chronicle the procedures and processes that were implemented in the development of the Jackson Heart Study Coordinating Center. The Jackson Heart Study (JHS) is a population-based investigation of traditional and emerging risk factors that predict progression to CVD among African Americans. In response to the struggle against CVD, the Jackson Heart Study has convened a professional, technical, and administrative staff with specific competence in the operation of a coordinating center to handle the wide variety of areas related to CVD studies. The Jackson Heart Study Coordinating Center (JHSCC) was created to assure validity of the JHS findings and provide the resources necessary to meet comprehensive statistical needs (planning, implementing and monitoring data analysis); data management (designing, implementing and managing data collection and quality control), and administrative support. The JHSCC began with a commitment to support study functions in order to increase participant recruitment, retention and safety, meet regulatory requirements, prepare progress reports, and facilitate effective communication with the community and between all JHS centers. The JHSCC facilitates the efforts of the JHS scientists through the development and implementation of the study protocol. The efforts of the JHSCC have resulted in the successful preparation of scientific reports and manuscripts for publication and presentation of study findings and results. In summary, the JHSCC has emerged as an effective research mechanism that serves as the driving force behind the Jackson Heart Study activities
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