2,773 research outputs found

    Resource shifts and adjustments in three counties of Tennessee\u27s central basin from 1860-1960

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    The purpose of this study was to explore the events, places, and people involved in the development of vocational education in agri-culture in Tennessee from its beginning in 1917 to 1955. There does not seem to be a comprehensive history of the develop-ment of vocational education in agriculture in Tennessee, should be made while those connected with its early infancy are living. Such a document should be compiled so that those interested in Such a study vocational education in agriculture in Tennessee could know and under-stand something of its beginning and growth. Such a document would be valuable in evaluating the growth, underlying causes and effects, and impact of vocational education in agriculture from its beginning on the people and the agricultural in-dustry in Tennessee. It was further hoped that this study might preserve some of the historical facts that were available which might otherwise become destroyed or lost. It should be pointed out that this study will pave the way for future studies and investigations that might be in historical areas of vocational agriculture. Finally, it was hoped that this study might provide enjoyment, fond memories for those who have participated in its past, and a sense of pride and achievement for those who have contributed to the growth and development of vocational education in agriculture in Tennessee

    An alternate method for achieving temperature control in the -130 C to 75 C range

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    Thermal vacuum testing often requires temperature control of chamber shrouds and heat exchangers within the -130 C to 75 C range. There are two conventional methods which are normally employed to achieve control through this intermediate temperature range: (1) single-pass flow where control is achieved by alternately pulsing hot gaseous nitrogen (GN2) and cold LN2 into the feed line to yield the setpoint temperature; and (2) closed-loop circulation where control is achieved by either electrically heating or LN2 cooling the circulating GN2 to yield the setpoint temperature. A third method, using a mass flow ratio controller along with modulating control valves on GN2 and LN2 lines, provides excellent control but equipment for this method is expensive and cost-prohibitive for all but long-term continuous processes. The single-pass method provides marginal control and can result in unexpected overcooling of the test article from even a short pulse of LN2. The closed-loop circulation method provides excellent control but requires an expensive blower capable of operating at elevated pressures and cryogenic temperatures. Where precise control is needed (plus or minus 2 C), single-pass flow systems typically have not provided the precision required, primarily because of overcooling temperature excursions. Where several individual circuits are to be controlled at different temperatures, the use of expensive cryogenic blowers for each circuit is also cost-prohibitive, especially for short duration of one-of-a-kind tests. At JPL, a variant of the single-pass method was developed that was shown to provide precise temperature control in the -130 C to 75 C range while exhibiting minimal setpoint overshoot during temperature transitions. This alternate method uses a commercially available temperature controller along with a GN2/LN2 mixer to dampen the amplitude of cold temperature spikes caused by LN2 pulsing. The design of the GN2/LN2 mixer, the overall control system configuration, the operational procedure, and the prototype system test results are described

    Predicting U.S. Jet Fighter Aircraft Introductions from 1944 to 1982: A Dogfight Between Regression and TFDEA

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    Since its inception in 2001, technology forecasting using data envelopment analysis (TFDEA) has been used with a number of applications. This paper presents a formal comparison of TFDEA to a previously published application from Technological Forecasting and Social Change by Joseph Martino. Using the data and Martino’s multiple regression model, we compare results obtained from TFDEA to those previously published. Both techniques predict the first flights of fighter jets introduced between 1960 and 1982 by using the first flights of aircraft introduced between 1944 and 1960. TFDEA was found to better predict the first flight dates than the forecast using multiple regression. These results indicate that TFDEA may be a powerful new technique for predicting complex technological trends and time to market for new products

    Improving Time to Market Forecasts: A Comparison of Two Technology Forecasting Techniques for Predicting U.S. Fighter Jet Introductions From 1944 to 1982

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    Since its origin in 2001, technology forecasting using data envelopment analysis (TFDEA) has been tested with a number of applications. This paper uses a previously published technology forecast comparison of U.S. fighter jets between the years 1944 and 1982 to compare TFDEA to basic regression. Both techniques use aircraft introduced between 1944 and 1960 to predict the first flights of those fighters introduced between 1960 and 1982. TFDEA was found to better predict the first flight dates than the forecast using regression. These results indicate that TFDEA may be a powerful new technique for predicting complex technological trends and time to market for new product

    A new approach for performing contamination control bakeouts in JPL thermal vacuum test chambers

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    Contamination control requirements for the Wide Field/Planetary Camera II (WF/PC II) are necessarily stringent to protect against post-launch contamination of the sensitive optical surfaces, particularly the cold charge coupled device (CCD) imaging surfaces. Typically, thermal vacuum test chambers have employed a liquid nitrogen (LN2) cold trap to collect outgassed contaminants. This approach has the disadvantage of risking recontamination of the test article from shroud offgassing during post-test warmup of the chamber or from any shroud warming of even a few degrees during the bakeout process. By using an enclave, essentially a chamber within a chamber, configured concentrically and internally within an LN2 shroud, a method was developed, based on a design concept by Taylor, for preventing recontamination of test articles during bakeouts and subsequent post-test warmup of the vacuum chamber. Enclaves for testing WF/PC II components were designed and fabricated, then installed in three of JPL's Environmental Test Lab chambers. The design concepts, operating procedures, and test results of this development are discussed

    Induced CNS expression of CXCL1 augments neurologic disease in a murine model of multiple sclerosis via enhanced neutrophil recruitment.

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    Increasing evidence points to an important role for neutrophils in participating in the pathogenesis of the human demyelinating disease MS and the animal model EAE. Therefore, a better understanding of the signals controlling migration of neutrophils as well as evaluating the role of these cells in demyelination is important to define cellular components that contribute to disease in MS patients. In this study, we examined the functional role of the chemokine CXCL1 in contributing to neuroinflammation and demyelination in EAE. Using transgenic mice in which expression of CXCL1 is under the control of a tetracycline-inducible promoter active within glial fibrillary acidic protein-positive cells, we have shown that sustained CXCL1 expression within the CNS increased the severity of clinical and histologic disease that was independent of an increase in the frequency of encephalitogenic Th1 and Th17 cells. Rather, disease was associated with enhanced recruitment of CD11b+ Ly6G+ neutrophils into the spinal cord. Targeting neutrophils resulted in a reduction in demyelination arguing for a role for these cells in myelin damage. Collectively, these findings emphasize that CXCL1-mediated attraction of neutrophils into the CNS augments demyelination suggesting that this signaling pathway may offer new targets for therapeutic intervention

    A Statement on the Appropriate Role for Research and Development in Climate Policy

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    This statement is issued by a group of economists and scientists which met at Stanford University on October 18, 2008 to discuss the role of research and development (R&D) in developing effective policies for addressing the adverse potential consequences of climate change. We believe that climate change is a serious issue that governments need to address. We also believe that research and development needs to be a central part of governments’ strategies for responding to this challenge. Solutions to manage long-term risks will require the development and global deployment of a range of technologies for energy supply and end-use, land-use, agriculture and adaptation that are not currently commercial. A key potential benefit of focused scientific and technological research and development investment is that it could dramatically reduce the cost of restricting greenhouse gas emissions by encouraging the development of more affordable, better performing technologies.

    Interferometric Observations of Explosive Variables: V838 Mon, Nova Aql 2005, and RS Oph

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    During the last two years we have used the Palomar Testbed Interferometer to observe several explosive variable stars, including V838 Monocerotis, V1663 Aquilae and recently RS Ophiuchi. We observed V838 Monocerotis approximately 34 months after its eruption, and were able to resolve the ejecta. Observations of V1663 Aql were obtained starting 9 days after peak brightness and continued for 10 days. We were able to resolve the milliarcsecond-scale emission and follow the expansion of the nova photosphere. When combined with radial-velocity information, these observations can be used to infer the distance to the nova. Finally we have resolved the recurrent nova RS Oph and can draw some preliminary conclusions regarding the emission morphology.Comment: 8 Pages, SPIE Astronomical Telescopes and Instrumentation 2006, Advances in Stellar Interferometery, 6268-16

    Clinical relevance of findings in trials of CBT for depression

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    Cognitive behavioural therapy (CBT) is beneficial in depression. Symptom scores can be translated into Clinical Global Impression (CGI) scale scores to indicate clinical relevance. We aimed to assess the clinical relevance of findings of randomised controlled trials (RCTs) of CBT in depression. We identified RCTs of CBT that used the Hamilton Rating Scale for Depression (HAMD). HAMD scores were translated into Clinical Global Impression – Change scale (CGI-I) scores to measure clinical relevance. One hundred and seventy datasets from 82 studies were included. The mean percentage HAMD change for treatment arms was 53.66%, and 29.81% for control arms, a statistically significant difference. Combined active therapies showed the biggest improvement on CGI-I score, followed by CBT alone. All active treatments had better than expected HAMD percentage reduction and CGI-I scores. CBT has a clinically relevant effect in depression, with a notional CGI-I score of 2.2, indicating a significant clinical response. The non-specific or placebo effect of being in a psychotherapy trial was a 29% reduction of HAMD
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