8,194 research outputs found

    Curbing Tax Expenditures

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    Reviews trends in tax expenditures and their effects and examines three options for raising tax revenue by applying limits to large and widely utilized tax preferences: a fixed percentage credit, a cap based on income, and a constant percentage reduction

    Prognostic Launch Vehicle Probability of Failure Assessment Methodology for Conceptual Systems Predicated on Human Causal Factors

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    Lessons learned from past failures of launch vehicle developments and operations were used to create a new method to predict the probability of failure of conceptual systems. Existing methods such as Probabilistic Risk Assessments and Human Risk Assessments were considered but found to be too cumbersome for this type of system-wide application for yet-to-be-flown vehicles. The basis for this methodology were historic databases of past failures, where it was determined that various faulty human-interactions were the predominant root causes of failure rather than deficient component reliabilities evaluated through statistical analysis. This methodology contains an expert scoring part which can be used in either a qualitative or a quantitative mode. The method produces two products: a numerical score of the probability of failure or guidance to program management on critical areas in need of increased focus to improve the probability of success. In order to evaluate the effectiveness of this new method, data from a concluded vehicle program (USAF's Titan IV with the Centaur G-Prime upper stage) was used as a test case. Although the theoretical vs. actual probability of failure was found to be in reasonable agreement (4.46% vs. 6.67% respectively) the underlying sub-root cause scoring had significant disparities attributable to significant organizational changes and acquisitions. Recommendations are made for future applications of this method to ongoing launch vehicle development programs

    Sea anemone model has a single Toll-like receptor that can function in pathogen detection, NF-κB signal transduction, and development

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    In organisms from insects to vertebrates, Toll-like receptors (TLRs) are primary pathogen detectors that activate downstream pathways, specifically those that direct expression of innate immune effector genes. TLRs also have roles in development in many species. The sea anemone Nematostella vectensis is a useful cnidarian model to study the origins of TLR signaling because its genome encodes a single TLR and homologs of many downstream signaling components, including the NF-κB pathway. We have characterized the single N. vectensis TLR (Nv-TLR) and demonstrated that it can activate canonical NF-κB signaling in human cells. Furthermore, we show that the intracellular Toll/IL-1 receptor (TIR) domain of Nv-TLR can interact with the human TLR adapter proteins MAL and MYD88. We demonstrate that the coral pathogen Vibrio coralliilyticus causes a rapidly lethal disease in N. vectensis and that heat-inactivated V. coralliilyticus and bacterial flagellin can activate a reconstituted Nv-TLR–to–NF-κB pathway in human cells. By immunostaining of anemones, we show that Nv-TLR is expressed in a subset of cnidocytes and that many of these Nv-TLR–expressing cells also express Nv-NF-κB. Additionally, the nematosome, which is a Nematostella-specific multicellular structure, expresses Nv-TLR and many innate immune pathway homologs and can engulf V. coralliilyticus. Morpholino knockdown indicates that Nv-TLR also has an essential role during early embryonic development. Our characterization of this primitive TLR and identification of a bacterial pathogen for N. vectensis reveal ancient TLR functions and provide a model for studying the molecular basis of cnidarian disease and immunity.IOS-1354935 - National Science Foundation (NSF); GRFP - National Science Foundation (NSF); GRFP - National Science Foundation (NSF); 1262934 - National Science Foundation (NSF); 2014-BSP - Arnold and Mabel Beckman Foundatio

    Exploratory study of several advanced nuclear-MHD power plant systems

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    Issued as Semiannual status report, and Final status report,. School of Mechanical Engineering Project no. E-25-624Final status report has title: Exploratory study of several advanced nuclear MHD power plant systemsContinued as school of Nuclear Engineering Project no. E-26-606 and School of Mechanical Engineering Project no. E-25-63

    LATERALITY AND ITS EFFECT ON LOWER EXTREMITY MUSCULOSKELETAL STIFFNESS IN MALE SOCCER PLAYERS AND TRACK RUNNERS

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    The purpose of this study was to determine the influence of laterality on lower extremity stiffness in healthy soccer players and track runners. Eight soccer players aged 15 to 17 years, and eight track runners, aged from 18 to 25 years performed a battery of tests (Single and double legged continuous straight and bent-legged jumping, and running) to determine lower extremity musculoskeletal stiffness. All participants were injury free at the time of testing. Statistical tests of the various all kinetic measures revealed that the track runners were asymmetrical in their musculoskeletal performance qualities, whereas, the soccer players displayed symmetry. Future research should examine lower extremity symmetry in an older group of soccer players, and the development of a training program to alter lower extremity stiffness into a typical range

    EVALUATING STRENGTH QUALITIES OF ATHLETES USING RELATIONSHIPS BETWEEN JUMP PROTOCOLS

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    Understanding the relationships between jump assessments may provide information of an athlete’s strength qualities. Elastic Utilisation Ratio (EUR) is calculated between countermovement jump (CMJ) and squat jump (SQJ) height, and is suggested to describe the stretch-shortening cycle ability of an athlete. Yet, knowledge of what constitutes a typical EUR range for an athlete remains unclear. The purpose of this study was to assess jump performance and the EUR of athletes from two sports (soccer and distance runners) using a portable forceplate. SQJ and CMJ heights were highly correlated (r>.90). Linear regression and standard error of estimate statistics were then used to estimate CMJ height and derive an expected EUR range. It was concluded, those athletes outside this predicted EUR range would benefit from specific training

    Optical Tweezers as an Effective Tool for Spermatozoa Isolation from Mixed Forensic Samples

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    A single focus optical tweezer is formed when a laser beam is launched through a high numerical aperture immersion objective. This objective focuses the beam down to a diffraction-limited spot, which creates an optical trap where cells suspended in aqueous solutions can be held fixed. Spermatozoa, an often probative cell type in forensic investigations, can be captured inside this optical trap and dragged one by one across millimeter-length distances in order to create a cluster of cells which can be subsequently drawn up into a capillary for collection. Sperm cells are then ejected onto a sterile cover slip, counted, and transferred to a tube for DNA analysis workflow. The objective of this research was to optimize sperm cell collection for maximum DNA yield, and to determine the number of trapped sperm cells necessary to produce a full STR profile. A varying number of sperm cells from both a single-source semen sample and a mock sexual assault sample were isolated utilizing optical tweezers and processed using conventional STR analysis methods. Results demonstrated that approximately 50 trapped spermatozoa were required to obtain a consistently full DNA profile. A complete, single-source DNA profile was also achieved by isolating sperm cells via optical trapping from a mixture of sperm and vaginal epithelial cells. Based on these results, optical tweezers are a viable option for forensic applications such as separation of mixed populations of cells in forensic evidence
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