131,601 research outputs found
Did Socrates Die? : a Note on the Moment of Change
No full textWhen an event occurs which involves a change from a state to a state not-, when does the change occur? This is known in the philosophical literature as the problem of the moment of change. I discuss a puzzle based on this problem raised by Sextus Empiricus in Against the Physicists. I compare two lines of solution, one provided by Hans Kamp’s work on the logic of change and the other inspired by Aristotle’s claim that change cannot happen at an instant. I end with a discussion of these solutions vis-à-vis the account of cessation implicatures proposed by Altshuler and Schwarzschild
Introducing Aggregate Return on Investment as a solution to the contradiction between some PME metrics and IRR
No full textThe Index Comparison Method (ICM) is a well-known approach for measuring a Private Equity Investment’s (PEI) performance. It is based on the construction of a benchmark portfolio that, each period, earns the index return. This generates a time series of interim net asset values that leads to a terminal NAV, from which an Internal Rate of Return is computed. However, the IRR is itself necessarily associated with its own time series of built-in NAVs, to which the IRR is applied. And, unfortunately, this series of values will be different from the aforementioned benchmark portfolio’s NAVs. As a result, the ICM approach rests on two contradictory sets of values, thereby rendering it illegitimate. Furthermore, the ICM approach does not preserve additivity of the rates of return, and, in principle, might even generate multiple IRRs. This paper presents the Aggregate Return on Investment (AROI), a metric which (i) uses one consistent time series of NAVs (the benchmark portfolio’s true values) (ii) preserves additivity, and (iii) does not incur the problem of multiple solutions
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
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
Effect of Chronic Obstructive Pulmonary Disease on Rate of Deposition of Aerosols in the Lung During Breath Holding
No full text"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.
DHCR7 mutations linked to higher vitamin D status allowed early human migration to Northern latitudes
No full textVitamin D is essential for a wide range of physiological processes including immune function and calcium homeostasis. Recent investigations have identified candidate genes which are strongly linked to concentrations of 25-hydroxyvitamin D. Since there is insufficient UVB radiation to induce year-round cutaneous synthesis of vitamin D at latitudes distant from the equator it is likely that these genes were subject to forces of natural selection. We used the fixation index (FST) to measure differences in allele frequencies in 993 individuals from ten populations to identify the presence of evolutionary selection in genes in the vitamin D pathway. We then explored the length of haplotypes in chromosomes to confirm recent positive selection
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
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