3,190 research outputs found
Education, Certification, and the Earnings of Industrial Accountants
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
Destabilization of cortical dendrites and spines by BDNF
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
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
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Plug-In Hybrid Electric Vehicle Value Proposition Study: Phase 1, Task 2: Select Value Propositions/Business Model for Further Study
The Plug-In Hybrid Electric Vehicle (PHEV) Value Propositions Workshop held in Washington, D.C. in December 2007 served as the Task 1 Milestone for this study. Feedback from all five Workshop breakout sessions has been documented in a Workshop Summary Report, which can be found at www.sentech.org/phev. In this report, the project team compiled and presented a comprehensive list of potential value propositions that would later serve as a 'grab bag' of business model components in Task 2. After convening with the Guidance and Evaluation Committee and other PHEV stakeholders during the Workshop, several improvements to the technical approach were identified and incorporated into the project plan to present a more realistic and accurate case study and evaluation. The assumptions and modifications that will have the greatest impact on the case study selection process in Task 2 are described in more detail in this deliverable. The objective of Task 2 is to identify the combination of value propositions that is believed to be achievable by 2030 and collectively hold promise for a sustainable PHEV market by 2030. This deliverable outlines what the project team (with input from the Committee) has defined as its primary scenario to be tested in depth for the remainder of Phase 1. Plans for the second and third highest priority/probability business scenarios are also described in this deliverable as proposed follow up case studies in Phase 2. As part of each case study description, the proposed utility system (or subsystem), PHEV market segment, and facilities/buildings are defined
Connectionist natural language parsing
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
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Plug-In Hybrid Electric Vehicle Value Proposition Study: Interim Report: Phase I Scenario Evaluation
Plug-in hybrid electric vehicles (PHEVs) offer significant improvements in fuel economy, convenient low-cost recharging capabilities, potential environmental benefits, and decreased reliance on imported petroleum. However, the cost associated with new components (e.g., advanced batteries) to be introduced in these vehicles will likely result in a price premium to the consumer. This study aims to overcome this market barrier by identifying and evaluating value propositions that will increase the qualitative value and/or decrease the overall cost of ownership relative to the competing conventional vehicles and hybrid electric vehicles (HEVs) of 2030 During this initial phase of this study, business scenarios were developed based on economic advantages that either increase the consumer value or reduce the consumer cost of PHEVs to assure a sustainable market that can thrive without the aid of state and Federal incentives or subsidies. Once the characteristics of a thriving PHEV market have been defined for this timeframe, market introduction steps, such as supportive policies, regulations and temporary incentives, needed to reach this level of sustainability will be determined. PHEVs have gained interest over the past decade for several reasons, including their high fuel economy, convenient low-cost recharging capabilities, potential environmental benefits and reduced use of imported petroleum, potentially contributing to President Bush's goal of a 20% reduction in gasoline use in ten years, or 'Twenty in Ten'. PHEVs and energy storage from advanced batteries have also been suggested as enabling technologies to improve the reliability and efficiency of the electric power grid. However, PHEVs will likely cost significantly more to purchase than conventional or other hybrid electric vehicles (HEVs), in large part because of the cost of batteries. Despite the potential long-term savings to consumers and value to stakeholders, the initial cost of PHEVs presents a major market barrier to their widespread commercialization. The purpose of this project is to identify and evaluate value-added propositions for PHEVs that will help overcome this market barrier. Candidate value propositions for the initial case study were chosen to enhance consumer acceptance of PHEVs and/or compatibility with the grid. Potential benefits of such grid-connected vehicles include the ability to supply peak load or emergency power requirements of the grid, enabling utilities to size their generation capacity and contingency resources at levels below peak. Different models for vehicle/battery ownership, leasing, financing and operation, as well as the grid, communications, and vehicle infrastructure needed to support the proposed value-added functions were explored during Phase 1. Rigorous power system, vehicle, financial and emissions modeling were utilized to help identify the most promising value propositions and market niches to focus PHEV deployment initiatives
Learning effective amino acid interactions through iterative stochastic techniques
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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