3,190 research outputs found

    Education, Certification, and the Earnings of Industrial Accountants

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    Utilizing a model of the relationship between skill accumulation and earnings known as human capital theory, we analyzed the incremental earnings associated with various educational and professional credential for a sample of members of the National Association of Accountants (NAA). Data were collected by means of a questionnaire survey of NAA members and were analyzed utilizing a multiple regression technique. Earnings is regressed on various education and certification variables. Employment characteristics and personal characteristics of the respondents are included as control variables. Our analysis documents positive earnings increments for the bachelor’s and MBA degrees and the CPA certificate. For the MBA and CPA, these returns are concentrated in the middle and later stages of accountants’ careers. Also, we examine the variation in these returns across different subgroups of our sample. Individuals in finance positions have more responsibility and are more upwardly mobile than those in traditional accounting jobs. Prior experience in public accounting is found to be a partial substitute for the above credentials. Finally, the credentials generated more consistent returns in smaller firms

    P2P: The Path to Prosperity

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    Destabilization of cortical dendrites and spines by BDNF

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    Particle-mediated gene transfer and two-photon microscopy were used to monitor the behavior of dendrites of individual cortical pyramidal neurons coexpressing green fluorescent protein (GFP) and brain-derived neurotrophic factor (BDNF). While the dendrites and spines of neurons expressing GFP alone grew modestly over 24-48 hr, coexpressing BDNF elicited dramatic sprouting of basal dendrites, accompanied by a regression of dendritic spines. Compared to GFP-transfected controls, the newly formed dendrites and spines were highly unstable. Experiments utilizing Trk receptor bodies, K252a, and overexpression of nerve growth factor (NGF) demonstrated that these effects were mediated by secreted BDNF interacting with extracellular TrkB receptors. Thus, BDNF induces structural instability in dendrites and spines, which, when restricted to particular portions of a dendritic arbor, may help translate activity patterns into specific morphological changes

    Statistical Inference for Exploratory Data Analysis and Model Diagnostics

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    We propose to furnish visual statistical methods with an inferential framework and protocol, modelled on confirmatory statistical testing. In this framework, plots take on the role of test statistics, and human cognition the role of statistical tests. Statistical significance of ‘discoveries’ is measured by having the human viewer compare the plot of the real dataset with collections of plots of simulated datasets. A simple but rigorous protocol that provides inferential validity is modelled after the ‘lineup’ popular from criminal legal procedures. Another protocol modelled after the ‘Rorschach’ inkblot test, well known from (pop-)psychology, will help analysts acclimatize to random variability before being exposed to the plot of the real data. The proposed protocols will be useful for exploratory data analysis, with reference datasets simulated by using a null assumption that structure is absent. The framework is also useful for model diagnostics in which case reference datasets are simulated from the model in question. This latter point follows up on previous proposals. Adopting the protocols will mean an adjustment in working procedures for data analysts, adding more rigour, and teachers might find that incorporating these protocols into the curriculum improves their students’ statistical thinking

    Connectionist natural language parsing

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    The key developments of two decades of connectionist parsing are reviewed. Connectionist parsers are assessed according to their ability to learn to represent syntactic structures from examples automatically, without being presented with symbolic grammar rules. This review also considers the extent to which connectionist parsers offer computational models of human sentence processing and provide plausible accounts of psycholinguistic data. In considering these issues, special attention is paid to the level of realism, the nature of the modularity, and the type of processing that is to be found in a wide range of parsers

    Learning effective amino acid interactions through iterative stochastic techniques

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    The prediction of the three-dimensional structures of the native state of proteins from the sequences of their amino acids is one of the most important challenges in molecular biology. An essential ingredient to solve this problem within coarse-grained models is the task of deducing effective interaction potentials between the amino acids. Over the years several techniques have been developed to extract potentials that are able to discriminate satisfactorily between the native and non-native folds of a pre-assigned protein sequence. In general, when these potentials are used in actual dynamical folding simulations, they lead to a drift of the native structure outside the quasi-native basin. In this study, we present and validate an approach to overcome this difficulty. By exploiting several numerical and analytical tools we set up a rigorous iterative scheme to extract potentials satisfying a pre-requisite of any viable potential: the stabilization of proteins within their native basin (less than 3-4 \AA cRMS). The scheme is flexible and is demonstrated to be applicable to a variety of parametrizations of the energy function and provides, in each case, the optimal potentials.Comment: Revtex 17 pages, 10 eps figures. Proteins: Structure, Function and Genetics (in press
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