25,062 research outputs found

    Principal Turnover in Illinois Public Schools, 2001-2008

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    Analyzes trends in turnover among public school principals in 2001-08 compared with 1987-2001, school-based and personal reasons for the moves, characteristics of their new positions, and the role of school accountability pressures. Examines implications

    Informed Consent and Dual Purpose Research

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    The ethical treatment of human participants in psychological research is regulated by both federal guidelines and the ethical standards of the American Psychological Association (APA). Under certain circumstances, however, both APA standards and federal regulations allow for exceptions for informed consent. In spite of the possibility of exception, a number of factors have made it difficult to conduct and publish research that does not incorporate informed consent. The authors consider these factors and propose 2 approaches that may reduce reluctance to consider exceptions to informed consent under appropriate circumstances. First, journals should not rely on informed consent as the only method of screening research for the ethical treatment of human participants. Second, efforts must be made to work with institutional review boards and other units that review psychological research to ensure that their members are aware of the conditions under which informed consent is considered reasonable. Failure to consider ethical research without informed consent may have serious ethical consequences for research

    An Examination of the Relationship Between Overall Efficiency and Farm Experience

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    This paper examines the relationship between overall efficiency and years of farm experience for a sample of Kansas farms. In addition to years of experience, overall efficiency is significantly related to farm size, percent of time devoted to farming, and percent acres owned.Farm Management,

    Vector and Axial Nucleon Form Factors:A Duality Constrained Parameterization

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    We present new parameterizations of vector and axial nucleon form factors. We maintain an excellent descriptions of the form factors at low momentum transfers, where the spatial structure of the nucleon is important, and use the Nachtman scaling variable xi to relate elastic and inelastic form factors and impose quark-hadron duality constraints at high momentum transfers where the quark structure dominates. We use the new vector form factors to re-extract updated values of the axial form factor from neutrino experiments on deuterium. We obtain an updated world average value from neutrino-d and pion electroproduction experiments of M_A = 1.014 +- 0.014 GeV/c2. Our parameterizations are useful in modeling neutrino interactions at low energies (e.g. for neutrino oscillations experiments). The predictions for high momentum transfers can be tested in the next generation electron and neutrino scattering experiments.Comment: 5 pages, 3 figures, to be published in EPJ

    How Do Analyst Recommendations Respond to Major News?

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    We examine how analysts respond to public information when setting stock recommendations. We model the determinants of analysts’ recommendation changes following large stock price movements. We find evidence of an asymmetry following large positive and negative returns. Following large stock price increases, analysts are equally likely to upgrade or downgrade. Following large stock price declines, analysts are more likely to downgrade. This asymmetry exists after accounting for investment banking relationships and herding behavior. This result suggests recommendation changes are “sticky” in one direction, with analysts reluctant to downgrade. Moreover, this result implies that analysts’ optimistic bias may vary through time

    A Study in Blue: The Baryon Content of Isolated Low Mass Galaxies

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    We study the baryon content of low mass galaxies selected from the Sloan Digital Sky Survey (SDSS DR8), focusing on galaxies in isolated environments where the complicating physics of galaxy-galaxy interactions are minimized. We measure neutral hydrogen (HI) gas masses and line-widths for 148 isolated galaxies with stellar mass between 10710^7 and 109.5M10^{9.5} M_{\odot}. We compare isolated low mass galaxies to more massive galaxies and galaxies in denser environments by remeasuring HI emission lines from the Arecibo Legacy Fast ALFA (ALFALFA) survey 40% data release. All isolated low mass galaxies either have large atomic gas fractions or large atomic gas fractions cannot be ruled out via their upper limits. We measure a median atomic gas fraction of fgas=0.82±0.13f_{\rm gas} = 0.82 \pm 0.13 for our isolated low mass sample with no systems below 0.30. At all stellar masses, the correlations between galaxy radius, baryonic mass and velocity width are not significantly affected by environment. Finally, we estimate a median baryon to total dynamical mass fraction of fbaryon,disk=0.15±0.18f_{\rm baryon, disk} = 0.15 \pm 0.18. We also estimate two different median baryon to halo mass fractions using the results of semi-analytic models (fbaryon,halo=0.04±0.06)(f_{\rm baryon, halo} = 0.04 \pm 0.06) and abundance matching (fbaryon,halo=0.04±0.02)(f_{\rm baryon, halo} = 0.04 \pm 0.02). Baryon fractions estimated directly using HI observations appear independent of environment and maximum circular velocity, while baryon fractions estimated using abundance matching show a significant depletion of baryons at low maximum circular velocities.Comment: Re-submitted to ApJ. Updated with referee's comments. 20 pages. Figure 4 and 5 illustrate our key results. Table 1 presents a small sample of isolated galaxies. Table 3 presents scaling relation fit

    LAND MARKET LIBERALIZATION AND WEALTH DIFFERENTIATED LAND ACCESS: PANEL EVIDENCE FROM HONDURAS AND PERU

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    We evaluate the impact of agricultural land market liberalization policies in Latin America by empirically examining the degree to which the reforms have broken down the dependence of operational area on owned area. We use panel data sets from Honduras and Peru to estimate the relationship between operational and owned land holdings for pre and post reform periods.Land Economics/Use,

    Advanced technology applications for second and third general coal gasification systems

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    The historical background of coal conversion is reviewed and the programmatic status (operational, construction, design, proposed) of coal gasification processes is tabulated for both commercial and demonstration projects as well as for large and small pilot plants. Both second and third generation processes typically operate at higher temperatures and pressures than first generation methods. Much of the equipment that has been tested has failed. The most difficult problems are in process control. The mechanics of three-phase flow are not fully understood. Companies participating in coal conversion projects are ordering duplicates of failure prone units. No real solutions to any of the significant problems in technology development have been developed in recent years
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