2,404 research outputs found

    Statistical Reporting of American Library Developments by the Federal Government

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    Letter From Anne Schick Hall to Eleanor Snell, April 13, 1970

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    This letter from Anne Schick, Ursinus College Class of 1957, congratulates Eleanor Snell on the occasion of her retirement from Ursinus College.https://digitalcommons.ursinus.edu/snell_docs/1065/thumbnail.jp

    Retention and performance during COVID-19: Prosociality perception, social isolation, and online engagement

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    The experiences of university students impacted by COVID-19 and circumstances surrounding their experiences, help inform the future of higher education in the United States. In the uncertain and rapidly evolving higher education system, understanding retention patterns of students has become increasingly complex. This study examined how self-perceived prosociality and self-perceived social isolation among university students in an online education environment relate to the intention to re-enroll in university and their academic achievement (Grade Point Average; GPA). Ninety-seven university and community college students completed an online survey. Based on previous literature, we expected women to report higher prosociality perceptions than men (e.g., Mavroveli & Sánchez-Ruiz, 2011; Ruckmani & Balachandra, 2015). We also expected online engagement to mediate the relationships between prosociality perceptions and GPA and retention intention, and between social isolation and GPA and retention intention, respectively. Except for the gender differences hypothesis, all other study hypotheses were not supported. Areas for future research include additional changes in higher education and student stressors. This study adds to the literature bridging educational and psychological research and highlights areas of potential growth for college students’ academic performance

    Measurement of Protein in Nearshore Marine Sediments

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    Proteinaceous material in marine sediments which is available to proteolytic hydrolysis has been measured using a new method. This technique utilizes Coomassie Blue dye binding, which has the advantage of being sensitive only to larger polypeptides. Substantial interferences from other sedmentary organic substances are overcome by using a standard additions approach in conjunction with enzymatic digestion of the protein. Although tedious, the technique provides acceptable precision and accuracy. Measurements of protein in surficial nearshore sediments of the Gulf of Maine and St. Croix yield values ranging from 0.1 to 2.2 mg g-1, which account for a minor fraction of total nitrogen or acid-hydrolyzable amino acids. Protein decreases downcore at a faster rate than either of these 2 indicators of nitrogenous material, indicating the greater lability of the truly proteinaceous material. Biomass comprises a minor portion of the measured protein

    Line tensions, correlation lengths, and critical exponents in lipid membranes near critical points

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    Membranes containing a wide variety of ternary mixtures of high chain-melting temperature lipids, low chain-melting temperature lipids, and cholesterol undergo lateral phase separartion into coexisting liquid phases at a miscibility transition. When membranes are prepared from a ternary lipid mixture at a critical composition, they pass through a miscibility critical point at the transition temperature. Since the critical temperature is typically on the order of room temperature, membranes provide an unusual opportunity in which to perform a quantitative study of biophysical systems that exhibit critical phenomena in the two-dimensional Ising universality class. As a critical point is approached from either high or low temperature, the scale of fluctuations in lipid composition, set by the correlation length, diverges. In addition, as a critical point is approached from low temperature, the line tension between coexisting phases decreases to zero. Here we quantitatively evaluate the temperature dependence of line tension between liquid domains and of fluctuation correlation lengths in lipid membranes in order to extract a critical exponent, nu. We obtain nu=1.2 plus or minus 0.2, consistent with the Ising model prediction nu=1. We also evaluate the probability distributions of pixel intensities in fluoresence images of membranes. From the temperature dependence of these distributions above the critical temperature, we extract an independent critical exponent beta=0.124 plus or minus 0.03 which is consistent with the Ising prediction of beta=1/8.Comment: 22 pages, 7 figure

    The transfer principle: A tool for complete case analysis

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    This paper gives a general method for deriving limiting distributions of complete case statistics for missing data models from corresponding results for the model where all data are observed. This provides a convenient tool for obtaining the asymptotic behavior of complete case versions of established full data methods without lengthy proofs. The methodology is illustrated by analyzing three inference procedures for partially linear regression models with responses missing at random. We first show that complete case versions of asymptotically efficient estimators of the slope parameter for the full model are efficient, thereby solving the problem of constructing efficient estimators of the slope parameter for this model. Second, we derive an asymptotically distribution free test for fitting a normal distribution to the errors. Finally, we obtain an asymptotically distribution free test for linearity, that is, for testing that the nonparametric component of these models is a constant. This test is new both when data are fully observed and when data are missing at random.Comment: Published in at http://dx.doi.org/10.1214/12-AOS1061 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org
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