Showing papers by "Wichita State University published in 2008"
TL;DR: The Dartmouth Stellar Evolution Database as mentioned in this paper is a collection of stellar evolution tracks and isochrones that spans a range of [Fe/H] from 2.5 to +0.5, [α/Fe] from 0.245 to 0.40, and initial He mass fractions from Y = 0.1 and 4 M
Abstract: The ever-expanding depth and quality of photometric and spectroscopic observations of stellar populations increase the need for theoretical models in regions of age-composition parameter space that are largely unexplored at present. Stellar evolution models that employ the most advanced physics and cover a wide range of compositions are needed to extract the most information from current observations of both resolved and unresolved stellar populations. The Dartmouth Stellar Evolution Database is a collection of stellar evolution tracks and isochrones that spans a range of [Fe/H] from –2.5 to +0.5, [α/Fe] from –0.2 to +0.8 (for [Fe/H] ≤ 0) or +0.2 (for [Fe/H] > 0), and initial He mass fractions from Y = 0.245 to 0.40. Stellar evolution tracks were computed for masses between 0.1 and 4 M☉, allowing isochrones to be generated for ages as young as 250 Myr. For the range in masses where the core He flash occurs, separate He-burning tracks were computed starting from the zero age horizontal branch. The tracks and isochrones have been transformed to the observational plane in a variety of photometric systems including standard UBV(RI)C, Stromgren uvby, SDSS ugriz, 2MASS JHKs, and HST ACS/WFC and WFPC2. The Dartmouth Stellar Evolution Database is accessible through a Web site at http://stellar.dartmouth.edu/~models/ where all tracks, isochrones, and additional files can be downloaded.
2,014 citations
TL;DR: The main components and architecture of RAVEN are described and recent flight test results are presented illustrating the applications discussed above.
Abstract: To investigate and develop unmanned vehicle systems technologies for autonomous multiagent mission platforms, we are using an indoor multivehicle testbed called real-time indoor autonomous vehicle test environment (RAVEN) to study long-duration multivehicle missions in a controlled environment. Normally, demonstrations of multivehicle coordination and control technologies require that multiple human operators simultaneously manage flight hardware, navigation, control, and vehicle tasking. However, RAVEN simplifies all of these issues to allow researchers to focus, if desired, on the algorithms associated with high-level tasks. Alternatively, RAVEN provides a facility for testing low-level control algorithms on both fixed- and rotary-wing aerial platforms. RAVEN is also being used to analyze and implement techniques for embedding the fleet and vehicle health state (for instance, vehicle failures, refueling, and maintenance) into UAV mission planning. These characteristics facilitate the rapid prototyping of new vehicle configurations and algorithms without requiring a redesign of the vehicle hardware. This article describes the main components and architecture of RAVEN and presents recent flight test results illustrating the applications discussed above.
452 citations
TL;DR: In this article, a cost analysis of grid-connected electric energy storage is presented in terms of the cost added to electricity stored and discharged, in US dollar per kilowatt hour.
Abstract: This paper presents a cost analysis of grid-connected electric energy storage. Various energy storage technologies are considered in the analysis. Life-cycle cost analysis is used. The results are presented in terms of the cost added to electricity stored and discharged, in US dollar per kilowatt hour. Results are compared with wholesale and retail electricity costs and with the cost of conventional pumped hydro storage.
285 citations
TL;DR: The results show that at the post adoption stage, perceived IS usefulness is a good predictor of extended usage and exploratory usage, However, surprisingly IS usefulness was found to explain a much larger variance in exploratory used, and information quality and system integration were found to influence IS usefulness.
280 citations
TL;DR: In this article, a greedy randomised multiobjective adaptive search metaheuristic is used to obtain an approximate pareto front (i.e. an approximate set of nondominated solutions).
Abstract: A great amount of energy is wasted in industry by machines that remain idle due to underutilisation. A way to avoid wasting energy and thus reducing the carbon print of an industrial plant is to consider minimisation of energy consumption objective while making scheduling decisions. To minimise energy consumption, the decision maker has to decide the timing and length of turn off/turn on operation (a setup) and also provide a sequence of jobs that minimises the scheduling objective, assuming that all jobs are not available at the same time. In this paper, a framework to solve a multiobjective optimisation problem that minimises total energy consumption and total tardiness is proposed. Since total tardiness problem with release dates is an NP‐hard problem, a new greedy randomised multiobjective adaptive search metaheuristic is utilised to obtain an approximate pareto front (i.e. an approximate set of non‐dominated solutions). Analytical Hierarchy Process is utilised to determine the ‘best’ alternative amon...
276 citations
TL;DR: The authors investigated the degree to which children's inference generation ability generalises across different media and predicts narrative comprehension over and above basic language skills and vocabulary and found that children's inferences had a significant contribution to children's narrative comprehension.
Abstract: In the present study, we investigated the degree to which children's inference generation ability generalises across different media and predicts narrative comprehension over and above basic language skills and vocabulary. To address both aims, we followed two cohorts of children aged 4 and 6 as they turned 6 and 8 years old, respectively. At each time point we assessed their inference and narrative comprehension skills using aural, televised and written stories. We also assessed their basic language skills and vocabulary. The findings demonstrated that children's inference generation skills were highly inter-related across different media for both cohorts and at both time points. Also, children's inference generation had a significant contribution to children's narrative comprehension over and above basic language skills, vocabulary and media factors. The current set of findings has important theoretical and practical implications for early diagnosis and intervention in young children's high-order comprehension skills.
257 citations
TL;DR: In this article, the authors investigated the links among organizational structure (formalization and integration), supply chain process variability, and performance as moderated by environmental uncertainty, and found that in a predictable demand environment, only formal control affects SPC variability, leading to improved financial results.
249 citations
TL;DR: Results show that most employers are not very proactive in hiring PWDs and thatmost employers hold stereotypical beliefs not supported by research evidence.
Abstract: The retirement of baby boomers along with a smaller cohort group of young people replacing them poses a challenge for employers in the future—where will they find the workers they need? One largely untapped source of human resources is people with disabilities (PWDs). Why have employers mostly ignored this large labor pool? This research used a semistructured interview approach with 38 executives across a broad array of industries and geographic regions to examine why employers don't hire PWDs and what they believe can be done to change this situation. Results show that most employers are not very proactive in hiring PWDs and that most employers hold stereotypical beliefs not supported by research evidence. © 2008 Wiley Periodicals, Inc.
224 citations
TL;DR: The findings suggest the value of a methodical assessment when developing a systematic plan for implementing an institutional culture of evidence-based practice.
Abstract: Title. Nurses’ perceptions of evidence-based nursing practice.
Aim. This paper is a report of a study to investigate Registered Nurses’ perceptions, attitudes and knowledge/skills associated with evidence-based practice.
Background. Evidence-based practice has emerged as a marker for healthcare quality. Previous studies have primarily used researcher-developed descriptive surveys to examine nurses’ perceptions, as well as facilitators and barriers, related to evidence-based practice. Research suggests the value of understanding the organizational context prior to taking steps to implement evidence-based practice.
Methods. This study, conducted in 2006, had a descriptive, cross-sectional survey design using a psychometrically-validated measure of evidence-based practice. All Registered Nurses (n = 1031) employed by a large medical centre in the United States of America were asked to complete the questionnaires. The final response rate was 40·9% (n = 422).
Findings. Participants had moderate scores on practice and attitudes towards evidence-based practice. The knowledge/skills mean scores were somewhat lower. Statistically significant differences were found for attitudes between those with baccalaureate and higher education compared to those with associate and diploma education. The two most cited barriers to implementing evidence-based practice were time and knowledge.
Conclusion. The findings suggest the value of a methodical assessment when developing a systematic plan for implementing an institutional culture of evidence-based practice.
211 citations
09 Jun 2008
TL;DR: This work has used the techniques described in this work to significantly reduce the provenance storage costs associated with constructing MiMI, a warehouse of data regarding protein interactions, as well as two provenance stores, Karma and PReServ, produced through workflow execution.
Abstract: As the world is increasingly networked and digitized, the data we store has more and more frequently been chopped, baked, diced and stewed. In consequence, there is an increasing need to store and manage provenance for each data item stored in a database, describing exactly where it came from, and what manipulations have been applied to it. Storage of the complete provenance of each data item can become prohibitively expensive. In this paper, we identify important properties of provenance that can be used to considerably reduce the amount of storage required.We identify three different techniques: a family of factorization processes and two methods based on inheritance, to decrease the amount of storage required for provenance. We have used the techniques described in this work to significantly reduce the provenance storage costs associated with constructing MiMI [22], a warehouse of data regarding protein interactions, as well as two provenance stores, Karma [31] and PReServ [20], produced through workflow execution. In these real provenance sets, we were able to reduce the size of the provenance by up to a factor of 20. Additionally, we show that this reduced store can be queried efficiently and further that incremental changes can be made inexpensively.
200 citations
TL;DR: Korte et al. as mentioned in this paper evaluated the isotopic record of climate change and carbon sequestration in the Late Paleozoic, using more than 2000 brachiopod shells from Carboniferous through Middle Permian (359-260 ǫ) strata.
TL;DR: This review discusses the diagnosis and both operative and nonoperative management of this shoulder condition that causes significant morbidity.
Abstract: Adhesive capsulitis is a musculoskeletal condition that has a disabling capability. This review discusses the diagnosis and both operative and nonoperative management of this shoulder condition that causes significant morbidity. Issues related to medications, rehabilitation, and post surgical considerations are discussed.
TL;DR: Careful analysis of the kinetic and thermodynamic data using the Marcus approach revealed that this novel feature is due to appropriately positioning the energy level of the charge-separated state below the triplet states of either of the donor and acceptor entities in both polar and nonpolar solvents, a feature that was not evident in donor-acceptor dyads constructed using symmetric tetrapyrroles as electron donors.
Abstract: The first example of covalently linked free-base corrole−fullerene dyads is reported. In the newly synthesized dyads, the free-energy calculations performed by employing the redox and singlet excited-state energy in both polar and nonpolar solvents suggested the possibility of electron transfer from the excited singlet state of corrole to the fullerene entity. Accordingly, steady-state and time-resolved emission studies revealed efficient fluorescence quenching of the corrole entity in the dyads. Further studies involving femtosecond laser flash photolysis and nanosecond transient absorption studies confirmed electron transfer to be the quenching mechanism, in which the electron-transfer product, the fullerene anion radical, was able to be spectrally characterized. The rate of charge separation, kCS, was found to be on the order of 1010−1011 s−1, suggesting an efficient photoinduced electron-transfer process. Interestingly, the rate of charge recombination, kCR, was slower by 5 orders of magnitude in nonp...
TL;DR: This article presents a polynomial-time centralized approximation algorithm that provably delivers a solution whose benefit is at least 1/4 (1/2 for uniform-size data items) of the optimal benefit of the cache placement problem of minimizing total data access cost in ad hoc networks with multiple data items and nodes with limited memory capacity.
Abstract: Data caching can significantly improve the efficiency of information access in a wireless ad hoc network by reducing the access latency and bandwidth usage. However, designing efficient distributed caching algorithms is nontrivial when network nodes have limited memory. In this article, we consider the cache placement problem of minimizing total data access cost in ad hoc networks with multiple data items and nodes with limited memory capacity. The above optimization problem is known to be NP-hard. Defining benefit as the reduction in total access cost, we present a polynomial-time centralized approximation algorithm that provably delivers a solution whose benefit is at least 1/4 (1/2 for uniform-size data items) of the optimal benefit. The approximation algorithm is amenable to localized distributed implementation, which is shown via simulations to perform close to the approximation algorithm. Our distributed algorithm naturally extends to networks with mobile nodes. We simulate our distributed algorithm using a network simulator (ns2) and demonstrate that it significantly outperforms another existing caching technique (by Yin and Cao [33]) in all important performance metrics. The performance differential is particularly large in more challenging scenarios such as higher access frequency and smaller memory.
TL;DR: Findings indicate that whether or not individuals are recruited from a community or tertiary sample, ME/CFS imposes substantial economic costs.
Abstract: ME/CFS is characterized by debilitating fatigue in addition to other physical and cognitive symptoms. It is estimated to affect over 800,000 adults in the U.S. ME/CFS often results in diminished functionality and increased economic impact. The economic impact of an illness is generally divided into two categories: direct and indirect costs. Despite high prevalence rates and the disabling nature of the illness, few studies have examined the costs of ME/CFS at the individual and societal level. In fact, of the four studies examining the economic impact of ME/ME/CFS only two used a U. S. sample. The current study used community and tertiary samples to examine the direct costs of ME/CFS. Using archival data, Study 1 examined the direct cost of ME/CFS in a community-based sample in Chicago. Study 2 estimated the direct cost of ME/CFS in a tertiary sample in Chicago. Both Study1 and Study 2 assessed direct costs using office visit costs, medical test costs, and medication costs. For Study 1, the annual direct total cost per ME/CFS patient was estimated to be $2,342, with the total annual direct cost of ME/CFS to society being approximately $2 billion. In Study 2, the annual direct was estimated to be $8,675 per ME/CFS patient, with the total annual direct cost of ME/CFS to society being approximately $7 billion. Using ME/CFS prevalence data of 0.42 and indirect costs estimates from Reynolds et al. (2004), the direct and indirect cost of ME/CFS to society was estimated to be $18,677,912,000 for the community sample and $23,972,300,000 for the tertiary sample. These findings indicate that whether or not individuals are recruited from a community or tertiary sample, ME/CFS imposes substantial economic costs.
TL;DR: In this article, the authors highlight the recent progress made in the design and study of self-assembled supramolecular architectures based on tetrapyrrole macrocycles as donors, and fullerene and carbon nanotubes as acceptors for electron and energy transfer applications in solution.
Abstract: This review article highlights the recent progress made in the design and study of self-assembled supramolecular architectures based on tetrapyrrole macrocycles as donors, and fullerene and carbon nanotubes as electron acceptors for electron and energy transfer applications in solution. The remarkable features of the utilized biomimetic organization principles viz., hydrogen bonding, π–π stacking, metal-mediated complexation, and electrostatic attraction in governing the stability and geometry of the nanohybrids, and their significance in controlling the structure and electron transfer properties are discussed.
TL;DR: Evaluating websites designed for older adults in terms of how well they adhere to ‘senior-friendly’ guidelines and overall ease of use and satisfaction indicates that the website most compliant with the ‘Seniors’ Guidelines resulted in higher task success, but did not result in significantly better efficiency, satisfaction, or preference.
Abstract: Older adults in the US are the fastest-growing demographic, and also the largest-growing group of internet users. The aim of this research was to evaluate websites designed for older adults in terms of (i) how well they adhere to 'senior-friendly' guidelines and (ii) overall ease of use and satisfaction. In Experiment I, 40 websites designed for older adults were heuristically evaluated based on their adherence to usability guidelines derived by the National Institute on Aging and the National Library of Medicine. In Experiment II, three websites with varying levels of guideline compliance were evaluated by older adults in a usability test. Results from this study indicate that the website most compliant with the 'senior-friendly' guidelines resulted in higher task success, but did not result in significantly better efficiency, satisfaction, or preference. These findings demonstrate the importance of using both guidelines and usability testing when designing websites for older adults.
TL;DR: Person with MR without DS exhibit similar age-related changes in VO2peak and peak HR as individuals without disabilities, but relative VO2 peak did not decline with age in persons with DS, suggesting that aerobic capacity exhibits a different age- related response in individuals with DS.
Abstract: Introduction: Persons with mental retardation (MR), particularly individuals with Down syndrome (DS), have been found to have attenuated peak exercise responses in previous research. However, it is unknown if the pattern of age-associated changes in HR or aerobic capacity (V[spacing dot above]O2peak) is similar to individuals without disabilities.
Purpose: To investigate age-related changes in aerobic capacity in persons withMR, with and without DS, using a retrospective analysis.
Methods: Data were collected in university research laboratories, using 180 persons with MR without DS, 133 persons with MR with DS, and 322 persons without disabilities in four age categories: 9-15, 16-21, 22-29, and 30-45 yr. Subjects underwent treadmill testing with peak HR and V[spacing dot above]O2peak measurements.
Results: Relative V[spacing dot above]O2peak was lowest for persons with DS across all age groups. V[spacing dot above]O2peak did not change after 16 yr in the individuals with DS, whereas the other groups exhibited a slight decline (~10 mL[middle dot]kg-1[middle dot]min-1) with age. Peak HR was overall different between all three groups (P < 0.001), and the youngest age group had the highest peak HR versus the other three age groups (P < 0.0001).
Conclusions: Persons with MR without DS exhibit similar age-related changes in V[spacing dot above]O2peak and peak HR as individuals without disabilities. Similar age-related changes were also observed for peak HR in individuals with DS, despite overall lower levels. However, relative V[spacing dot above]O2peak did not decline with age in persons with DS, suggesting that aerobic capacity exhibits a different age-related response in individuals with DS.
TL;DR: Peer deviancy training occurs in early childhood and may serve as an independent risk mechanism in addition to peer coercion for early-onset, persisting conduct problems.
Abstract: The prospective relationships of conduct problems and peer coercion and deviancy training during kindergarten (mean age = 5.3 years) to overt and covert conduct problems in third–fourth grade were examined in a sample of 267 boys and girls. Coercion and deviancy training were distinct peer processes. Both were associated with earlier child conduct problems but were differentially associated with child impulsivity, verbal ability, anxiety, peer rejection, and deviant peer affiliation. Coercion by peers predicted overt conduct problems and peer deviancy training and the interaction of deviancy training and coercion predicted covert conduct problems in third–fourth grade. Peer deviancy training occurs in early childhood and may serve as an independent risk mechanism in addition to peer coercion for early-onset, persisting conduct problems.
TL;DR: The Dartmouth Stellar Evolution Database as discussed by the authors is a collection of stellar evolution tracks and isochrones that spans a range of [Fe/H] from -2.5 to +0.5, [alpha/Fe] from −0.2 to + 0.8, and initial He mass fractions from Y=0.245 to 0.40.
Abstract: The ever-expanding depth and quality of photometric and spectroscopic observations of stellar populations increase the need for theoretical models in regions of age-composition parameter space that are largely unexplored at present. Stellar evolution models that employ the most advanced physics and cover a wide range of compositions are needed to extract the most information from current observations of both resolved and unresolved stellar populations. The Dartmouth Stellar Evolution Database is a collection of stellar evolution tracks and isochrones that spans a range of [Fe/H] from -2.5 to +0.5, [alpha/Fe] from -0.2 to +0.8 (for [Fe/H] 0), and initial He mass fractions from Y=0.245 to 0.40. Stellar evolution tracks were computed for masses between 0.1 and 4 Msun, allowing isochrones to be generated for ages as young as 250 Myr. For the range in masses where the core He flash occurs, separate He-burning tracks were computed starting from the zero age horizontal branch. The tracks and isochrones have been transformed to the observational plane in a variety of photometric systems including standard UBV(RI)c, Stromgren uvby, SDSS ugriz, 2MASS JHKs, and HST ACS-WFC and WFPC2. The Dartmouth Stellar Evolution Database is accessible through a website at this http URL where all tracks, isochrones, and additional files can be downloaded.
TL;DR: In this paper, the authors present a framework for analyzing the security needs of women passengers on public transport, focusing on women's reported victimization, issues related to calculating the risk of being a crime victim, the rationality of women's fear of crime and disorder, and the need for effective and comprehensive crime prevention measures to address these security related issues.
Abstract: Managers of public transport systems seeking to maintain or increase ridership need to be aware of the security needs of passengers on their systems. A recent review, edited by Smith and Cornish (2006), of five different types of crime and disorder on public transport looked at situational crime prevention measures currently used, or proposed for use, against these offenses. The present analysis draws on this work to present a framework for analyzing the security needs of women passengers. The discussion reviews previous research in four key areas: (1) women's reported victimization, (2) issues related to calculating the risk of being a crime victim, (3) the rationality of women's fear of crime and disorder, and (4) the need for effective and comprehensive crime prevention measures to address these security-related issues. The “whole journey” approach is used to highlight aspects of the transit journey for women passengers that require special attention among transport providers, local governmental authorities (including police departments), policy makers, and researchers.
TL;DR: This article applied a Markov-switching model to U.S. home prices, and compared the performance with autoregressive-moving average (ARMA) and generalized auto-regressive conditional heteroscedastic (GARCH) models.
Abstract: The tremendous rise in house prices over the last decade has been both a national and a global phenomenon. The growth of secondary mortgage holdings and the increased impact of house prices on consumption and other components of economic activity imply ever-greater importance for accurate forecasts of home price changes. Given the boom–bust nature of housing markets, nonlinear techniques seem intuitively very well suited to forecasting prices, and better, for volatile markets, than linear models which impose symmetry of adjustment in both rising and falling price periods. Accordingly, Crawford and Fratantoni (Real Estate Economics 31:223–243, 2003) apply a Markov-switching model to U.S. home prices, and compare the performance with autoregressive-moving average (ARMA) and generalized autoregressive conditional heteroscedastic (GARCH) models. While the switching model shows great promise with excellent in-sample fit, its out-of-sample forecasts are generally inferior to more standard forecasting techniques. Since these results were published, some researchers have discovered that the Markov-switching model is particularly ill-suited for forecasting. We thus consider other non-linear models besides the Markov switching, and after evaluating alternatives, employ the generalized autoregressive (GAR) model. We find the GAR does a better job at out-of-sample forecasting than ARMA and GARCH models in many cases, especially in those markets traditionally associated with high home-price volatility.
TL;DR: In this article, a computational methodology for dynamic description of rigid multibody systems with translational clearance joints is presented and discussed, and the proposed methodology takes into account these four different situations.
Abstract: A computational methodology for dynamic description of rigid multibody systems with translational clearance joints is presented and discussed in this work. Over the past years, extensive work has been done to study the dynamic effect of the revolute joints with clearance in multibody systems, in contrast with the little work devoted to model translational joints with clearance. In a joint with translation clearance, there are many possible ways to set the physical configuration between the slider and guide, namely: (i) no contact between the two elements, (ii) one corner of the slider in contact with the guide surface, (iii) two adjacent slider corners in contact with the guide surface, and (iv) two opposite slider corners in contact with the guide surfaces. The proposed methodology takes into account these four different situations. The conditions for switching from one case to another depend on the system dynamics configuration. The existence of a clearance in a translational joint removes two kinematic constraints from a planar system and introduces two extra degrees of freedom in the system. Thus, a translational clearance joint does not constrain any degree of freedom of the mechanical system but it imposes some restrictions on the slider motion inside the guide limits. When the slider reaches the guide surfaces, an impact occurs and the dynamic response of the joint is modeled by contact-impact forces. These forces are evaluated here with continuous contact force law together with a dissipative friction force model. The contact-impact forces are introduced into the system's equations of motion as external generalized forces. The proposed methodology is applied to a planar multibody mechanical system with a translational clearance joint in order to demonstrate its features.
TL;DR: In this article, the authors investigate the equity market timing hypothesis of capital structure in major industrialized (G-7) countries and find that leverage of firms is negatively related to the historical market-to-book ratio in all G-7 countries.
Abstract: We investigate the equity market timing hypothesis of capital structure in major industrialized (G-7) countries. As claimed by its proponents, we find that leverage of firms is negatively related to the historical market-to-book ratio in all G-7 countries. However, this negative relationship cannot be attributed to equity market timing. We find no association between equity issues and market-to-book ratios at the time of equity financing decisions by Japanese firms. Firms in all G-7 countries, except Japan, undo the effect of equity issuance and the impact of equity market timing attempts on leverage is short lived. This is inconsistent with the prediction of the equity market timing hypothesis and more in line with dynamic trade-off model.
TL;DR: The thresholds of lower extremity muscle strength below which assistance is required to perform ADL in community-dwelling older adults were identified and results indicate that the muscular strength of hip extensors is more important in performing ADL than other muscles of the lower extremities.
Abstract: Objective: To determine the thresholds of lower extremity muscle strength below which performing activities of daily living (ADL) is impaired in older adults.Design: Cross-sectional.Setting: Community.Subjects: Forty-nine older adults (81—89 years) were divided into an independent group (n = 25) who needed no assistance and a dependent group (n = 24) who needed assistance to perform ADL.Interventions: Not applicable.Main measures: Functional independence measures to determine level of disability and muscular strength of hip flexors, hip extensors, knee flexors, knee extensors and ankle dorsiflexors assessed by a hand-held dynamometer (HHD). Muscle groups were tested separately for each leg and values were averaged for the two legs. A ratio of maximal muscular strength to body weight was calculated by dividing the muscular strength (N) by body weight (kg).Results: Muscular strength thresholds to perform ADL independently were 2.3 N/kg for hip flexors, 1.7 N/kg for hip extensors, 0.7 N/kg for knee flexors, ...
TL;DR: In this paper, generalized autoregressive conditional heteroscedasticity (GARCH) effects imply the probability of large losses is greater than standard mean-variance analysis suggests.
Abstract: Generalized autoregressive conditional heteroscedasticity (GARCH) effects imply the probability of large losses is greater than standard mean-variance analysis suggests. Accurately capturing GARCH ...
TL;DR: In this article, the authors theoretically and empirically investigate the role of information on the cross section of stock returns and firms' cost of capital when investors face estimation risk and learn from noisy signals of uncertain quality.
Abstract: We theoretically and empirically investigate the role of information on the cross section of stock returns and firms' cost of capital when investors face estimation risk and learn from noisy signals of uncertain quality. The resultant equilibrium is an information-dependent conditional CAPM. We find strong empirical support for the model. Innovations in market volatility, oil prices, exchange rates, and dispersion of analysts' forecasts not only help explain the cross section of stock returns, but their influence depends on the stock's systematic estimation risk. Moreover, dividend and share repurchase initiations have significant downward announcement effects on estimated betas and their standard errors. (JEL D83, D92, E22) How investors process new return-related information and how this information affects equilibrium asset prices is a central issue in finance; it is of substantial interest not only to financial economists seeking to understand the informational efficiency of security prices, but also to investment practitioners who must make investment decisions in the face of continually arriving information. In the textbook capital asset pricing model (CAPM), which assumes that the investment opportunity set is common knowledge, prices simply adjust to new information so as to fall along the new security pricing line. However, this model of information absorption (in security markets) is not satisfactory from
TL;DR: In this article, the damage resistance and tolerance of flat [(0/45),/core/(45/0), ] sandwich plates with honeycomb core subjected to low-velocity impacts using hemispherical steel impactors has been investigated experimentally.
Abstract: The damage resistance and tolerance of flat [(0/45),/core/(45/0), ] sandwich plates with honeycomb core subjected to low-velocity impacts using hemispherical steel impactors has been investigated experimentally. The effects of impactor diameter on the impact behavior, resulting impact damage states, and residual strength under in-plane compressive loading was of particular interest. The impact responses characterized in terms of peak impact force was observed to be dependent on the facesheet type, core thickness, and impactor size, but was found to be independent of the boundary support conditions. The smaller impactor produced damage states characterized by residual dent depths that were comparable to the core thickness, accompanied by visible facesheet fractures. The larger diameter impactor produced damage states with large core damage regions but with dent depths less than the facesheet thickness. Under in-plane compressive loading, depending on the impact damage state, contrasting failure mechanisms ...
TL;DR: This paper examined outside director compensation for a sample of 237 Fortune 500 firms over the 1998-2004 period and found a trend towards fixed-value equity compensation and away from cash only and fixed-number equity compensation.
TL;DR: This paper examined the relation between a firm's campaign contributions and lobbying expenditures and its Tobin's q and found little relation between q and political contributions, suggesting that campaign contributions may not have long term effects on political markets.
Abstract: We examine the relation between a firm’s campaign contributions and lobbying expenditures and its Tobin’s q. We follow other studies that use q to measure the value of the firm’s intangible capital (e.g., the value of advertising, R&D, or environmental performance). Researchers have found a positive and significant relation between intangible assets and q. If political capital exists, it is an intangible asset. However, we find little relation between q and political contributions, suggesting that campaign contributions may not have long term effects on political markets. This is consistent with the view that contributions are done by firms as a response to a short term opportunity not as a way of building long-term political capital.