1,899 research outputs found

    Received optical power calculations for optical communications link performance analysis

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    The factors affecting optical communication link performance differ substantially from those at microwave frequencies, due to the drastically differing technologies, modulation formats, and effects of quantum noise in optical communications. In addition detailed design control table calculations for optical systems are less well developed than corresponding microwave system techniques, reflecting the relatively less mature state of development of optical communications. Described below are detailed calculations of received optical signal and background power in optical communication systems, with emphasis on analytic models for accurately predicting transmitter and receiver system losses

    Enhancement of the CAVE computer code

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    The computer code CAVE (Conduction Analysis via Eigenvalues) is a convenient and efficient computer code for predicting two dimensional temperature histories within thermal protection systems for hypersonic vehicles. The capabilities of CAVE were enhanced by incorporation of the following features into the code: real gas effects in the aerodynamic heating predictions, geometry and aerodynamic heating package for analyses of cone shaped bodies, input option to change from laminar to turbulent heating predictions on leading edges, modification to account for reduction in adiabatic wall temperature with increase in leading sweep, geometry package for two dimensional scramjet engine sidewall, with an option for heat transfer to external and internal surfaces, print out modification to provide tables of select temperatures for plotting and storage, and modifications to the radiation calculation procedure to eliminate temperature oscillations induced by high heating rates. These new features are described

    Building Bridges Between Communication Studies and Community: A Praxis-Approach

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    In an effort to demonstrate the field’s usefulness and essentiality to our world, communication studies’ praxis orientation needs to be clearly pursued and publicized. Implementing service-learning into the communication studies classroom could achieve this goal. Through extending the scholarship of Britt (2012) and Pollack (1999), this article proposes that communication educators ground and articulate their service-learning pedagogy from three different paradigmatic lenses; the experiential paradigm, the social change paradigm, and the citizenship paradigm. Moreover, communication administrators ought to understand the different paradigmatic foundations, which drive service-learning enactment, in an effort to not privilege one perspective over another. The service-learning literature is vast and discusses service-learning’s history, definitional ground, and benefits. This article responds to one criticism of service-learning and provides a way in which communication educators and administrators could respond. By implementing service learning from a clearly articulated paradigmatic foundation, the pedagogy’s praxis orientation is strengthened, opening up the opportunity for more bridges to be built between academy and community

    The Selection Process and Characteristics of Judges Appointed to the US Courts of Appeal: From Carter to Clinton

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    Judges who are appointment to serve on the US Courts of Appeal have the power to change government policy and influence our daily lives. Each President has the opportunity to make an impact on the United States with the types of judges that he chooses to appoint. This study examines the process of nominating and selecting judges, as well as the characteristics of those who have been appointment to serve on the bench. Using data from previous studies conducted by Sheldon Goldman, as well as data gathered from Senate Judiciary Clinton, during his first term in office, to those judges appointed by Presidents Bush, Reagan, and Carter. President Clintong has surpassed President Carter in appointing well qualified women and minority judges to the bench

    Financial Education Program Evaluation

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    This study illustrates the process of program evaluation using a logic model. Guided by the Transtheoretical Model of Change and a logic model, this study evaluated the effectiveness of a Retirement and Savings Seminar by measuring participant (n = 54) satisfaction, financial knowledge, financial confidence, and financial behavior change compared to a similar group of 134 non-participants. Participants were very satisfied with the seminar. Their financial knowledge and confidence scores significantly increased from pretest to posttest. Financial knowledge and confidence scores improved more than the comparison group while controlling for group differences in age, income, and pretest scores. Two months later, participants were more likely than the comparison group to have adopted positive financial behaviors as measured by the Financial Preparedness for Retirement Scale. Financial educators can use this study as a model for planning, conducting, and evaluating their program

    The Labour Government, the Treasury and the £6 pay policy of July 1975

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    The 1974-79 Labour Government was elected in a climate of opinion that was fiercely opposed to government intervention in the wage determination process, and was committed to the principles of free collective bargaining in its manifestoes. However, by December 1974 the Treasury was advocating a formal incomes policy, and by July 1975 the government had introduced a £6 flat rate pay norm. With reference to archival sources, the paper demonstrates that TUC and Labour Party opposition to incomes policy was reconciled with the Treasury's advocacy by limiting the Bank of England‟s intervention in the foreign exchange market when sterling came under pressure. This both helped to achieve the Treasury's objective of improving the competitiveness of British industry, and acted as a catalyst for the introduction of incomes policy because the slide could be attributed to a lack of market confidence in British counter-inflation policy

    Effects of mesenchymal stromal cells versus serum on tendon healing in a controlled experimental trial in an equine model

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    Abstract Background Mesenchymal stromal cells (MSC) have shown promising results in the treatment of tendinopathy in equine medicine, making this therapeutic approach seem favorable for translation to human medicine. Having demonstrated that MSC engraft within the tendon lesions after local injection in an equine model, we hypothesized that they would improve tendon healing superior to serum injection alone. Methods Quadrilateral tendon lesions were induced in six horses by mechanical tissue disruption combined with collagenase application 3 weeks before treatment. Adipose-derived MSC suspended in serum or serum alone were then injected intralesionally. Clinical examinations, ultrasound and magnetic resonance imaging were performed over 24 weeks. Tendon biopsies for histological assessment were taken from the hindlimbs 3 weeks after treatment. Horses were sacrificed after 24 weeks and forelimb tendons were subjected to macroscopic and histological examination as well as analysis of musculoskeletal marker expression. Results Tendons injected with MSC showed a transient increase in inflammation and lesion size, as indicated by clinical and imaging parameters between week 3 and 6 (p < 0.05). Thereafter, symptoms decreased in both groups and, except that in MSC-treated tendons, mean lesion signal intensity as seen in T2w magnetic resonance imaging and cellularity as seen in the histology (p < 0.05) were lower, no major differences could be found at week 24. Conclusions These data suggest that MSC have influenced the inflammatory reaction in a way not described in tendinopathy studies before. However, at the endpoint of the current study, 24 weeks after treatment, no distinct improvement was observed in MSC-treated tendons compared to the serum-injected controls. Future studies are necessary to elucidate whether and under which conditions MSC are beneficial for tendon healing before translation into human medicine

    Regional Consumer Price Comparisons--With Specific Applications to Minnesota

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    Supported by the Northwest Area Foundation and the Minnesota Agricultural Experiment Station. State and Regional Research Center Working Paper 89-03

    Coupling to haloform molecules in intercalated C60?

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    For field-effect-doped fullerenes it was reported that the superconducting transition temperature Tc is markedly larger for C60.2CHX_3 (X=Cl, Br) crystals, than for pure C60. Initially this was explained by the expansion of the volume per C60-molecule and the corresponding increase in the density of states at the Fermi level in the intercalated crystals. On closer examination it has, however, turned out to be unlikely that this is the mechanism behind the increase in Tc. An alternative explanation of the enhanced transition temperatures assumes that the conduction electrons not only couple to the vibrational modes of the C60-molecule, but also to the modes of the intercalated molecules. We investigate the possibility of such a coupling. We find that, assuming the ideal bulk structure of the intercalated crystal, both a coupling due to hybridization of the molecular levels, and a coupling via dipole moments should be very small. This suggests that the presence of the gate-oxide in the field-effect-devices strongly affects the structure of the fullerene crystal at the interface.Comment: 4 pages, 1 figure, to be published in PRB (rapid communication
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