131,240 research outputs found
Semi-classical analysis of scattering of deformed heavy-ions below the Coulomb barrier
No full textA semi-classical calculation is performed to predict spin polarisation observables for elastic heavy ion scattering of a quadrupole deformed projectile from a spinless target below the Coulomb barrier. A method introduced by Sukumar and Brink, based on a path integral formalism and a consistent quantum-mechanical treatment of both the relative motion and internal degrees of freedom is used. This method is an improvement on earlier semi-classical calculations based on the Alder and Winther method which, in the absence of excitation, predict cross-sections which are independent of the polarisation of the initial spin state. The expressions developed by Sukumar and Brink are evaluated to first order in the quadrupole moment of the projectile. Polarisation observables are compared to both quatum-mechanical coupled channels calculations and other approximate semi-classical calculations; good agreement is found. For backward angles, simple expressions for polarisation observables valid to first order in the quadrupole moment are given. © 1995
MeSH term explosion and author rank improve expert recommendations
No full textInformation overload is an often-cited phenomenon that reduces the productivity, efficiency and efficacy of scientists. One challenge for scientists is to find appropriate collaborators in their research. The literature describes various solutions to the problem of expertise location, but most current approaches do not appear to be very suitable for expert recommendations in biomedical research. In this study, we present the development and initial evaluation of a vector space model-based algorithm to calculate researcher similarity using four inputs: 1) MeSH terms of publications; 2) MeSH terms and author rank; 3) exploded MeSH terms; and 4) exploded MeSH terms and author rank. We developed and evaluated the algorithm using a data set of 17,525 authors and their 22,542 papers. On average, our algorithms correctly predicted 2.5 of the top 5/10 coauthors of individual scientists. Exploded MeSH and author rank outperformed all other algorithms in accuracy, followed closely by MeSH and author rank. Our results show that the accuracy of MeSH term-based matching can be enhanced with other metadata such as author rank
Regulation of bone quality and calcium absorption in obesity and during caloric restriction in women
No full textWeight loss (WL) is associated with loss of bone loss due to several factors such as decrease in intake of calcium, true fractional calcium absorption (TFCA), serum insulin like growth factor -1 (IGF-1) , reduced weight bearing . The aim in this dissertation was to understand whether a higher intake of dietary protein and vitamin D can attenuate bone loss during caloric restriction (CR), and addresses bone quality and altered hormonal milieu in obesity. In the first trial, our goal was to examine how bone responds to CR during a 1 year randomized trial using 2 levels of protein intake with controlled calcium intake of 1.2 g/d in both groups. Forty seven women were randomized to either a normal (18%) or higher (24%) protein intake for 1 year. Our results showed greater loss of BMD at certain sites and lower IGF-1 in the NP compared to HP diet (p <0.05). The second trial hypothesized that a higher compared to normal vitamin D supplementation will attenuate the decrease in TFCA associated with CR. Eighty four women were supplemented with either 2500 IU/d or 400 IU/d of vitamin D3 for 6 weeks during WL or weight maintenance (WM). TFCA increased with 2500 IU/d D supplementation in the WM-D group by 3.7% (p <0.05) however did not attenuate the decrease in TFCA associated with CR, with the greatest increase in 25 hydroxy vitamin D (25OHD) in the WL-D group. These findings suggest that vitamin D supplementation does not attenuate the decrease in TFCA associated with CR. The cross sectional study in this dissertation aimed at evaluating bone quality in obesity using peripheral quantitative computed tomography (pQCT). Our results in 211 women showed that obesity is associated with higher trabecular bone and lower cortical BMD. A separate case control clinical study in 111 women shows that high serum PTH in obesity is also associated with higher monocyte chemoattractant protein (MCP-1). This unique effect of parathyroid hormone (PTH) on MCP-1 is independent of the level of adiposity. Together these studies evaluate nutrient supplementation in attenuating bone loss during CR and help better understand bone quality and higher serum PTH in obesity.Ph. D.Includes bibliographical referencesIncludes vitaby Deeptha Sukuma
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
ESSAYS ON INSTITUTIONS, FINANCIAL DEVELOPMENT, AND ECONOMIC GROWTH
No full textA number of recent papers using a linear specification have indicated that private property institutions are a fundamental determinant of growth. In my first paper, I use a semi-nonparametric partially linear model to provide evidence against a linear specification and to support nonlinearities in the relationship. The findings indicate that the exogenous component of private property institutions contributes positively to economic growth for countries in the lower and middle stages of private property institutions and have a negative relationship with economic growth of countries having the highest level of private property institutions. These results are confirmed when using an appropriate parametric specification and estimation by GMM. When using different measures of private property institutions as the 'rule of law' and 'political freedom', the results are consistent. The second paper documents a nonlinear relationship between financial development and income inequality across developing and developed countries, and uncovers the empirical root of this phenomenon. The source is in two parts: there is a close relationship between the level of economic development and the level of financial development across countries; and the impact of financial development on income inequality is contingent on the level of economic development. The 1990s saw considerable economic turbulence due to varying degrees of financial crisis in many countries in Asia and Latin America. In the third paper, I document that a combination of external shocks, weak institutional background and excessive bank lending contributed to the differential responses by countries to financial crisis. Using a version of the models of Bernanke and Gertler (1990) and Jensen and Meckling (1976), the paper builds a theoretical model to show that institutional problems, coupled with external shocks, can affect the capital structure of firms and lead to a choice of projects having low net present value, which carries implications for aggregate investment and growth.. In the empirical counterpart, the study shows that proxies for weak institutions of corporate finance, excessive bank lending and terms of trade shocks played a central role in determining the magnitude of growth and investment collapse as observed in these regions
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Scholarly Communication and Publishing Lunch and Learn Talk #11: The ULS Open Access Author Fee Fund
No full textAt the May 2014 talk, you will learn about the ULS Open Access Author Fee Fund--what it is, why we do it, how it works, and how the program is going so far
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