Wichita State University

About: Wichita State University is a education organization based out in Wichita, Kansas, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 4988 authors who have published 9563 publications receiving 253824 citations. The organization is also known as: WSU & Fairmount College.

Kalman filtering for continuous-time uncertain systems with Markovian jumping parameters

Abstract: Studies the problem of Kalman filtering for a class of uncertain linear continuous-time systems with Markovian jumping parameters. The system under consideration is subjected to time-varying norm-bounded parameter uncertainties in the state and measurement equations. Stochastic quadratic stability of the above system is analyzed. A state estimator is designed such that the covariance of the estimation error is guaranteed to be within a certain bound for all admissible uncertainties, which is in terms of solutions of two sets of coupled algebraic Riccati equations.

The Y2 Isochrones for α-Element Enhanced Mixtures

Abstract: We present a new set of isochrones in which the effect of the α-element enhancement is fully incorporated. These isochrones are an extension of the already published set of Y2 Isochrones (our Paper I), constructed for the scaled-solar mixture. As in Paper I, helium diffusion and convective core overshoot have been taken into account. The range of chemical compositions covered is 0.00001 ≤ Z ≤ 0.08. The models were evolved from the pre-main-sequence stellar birthline to the onset of helium burning in the core. The age range of the full isochrone set is 0.1-20 Gyr, while younger isochrones of age 1-80 Myr are also presented up to the main-sequence turn-off. Combining this set with that of Paper I for scaled-solar mixture isochrones, we provide a consistent set of isochrones that can be used to investigate populations of any value of α-enhancement. We confirm the earlier results of Paper I that inclusion of α-enhancement effects further reduces the age estimates of globular clusters by approximately 8% if [α/Fe]= +0.3. It is important to note the metallicity dependence of the change in age estimates (larger age reductions in lower metallicities). This reduces the age gap between the oldest metal-rich and metal-poor Galactic stellar populations and between the halo and the disk populations. We also investigate whether the effects of α-enhancement can be mimicked by increasing the total metal abundance in the manner proposed by Salaris and collaborators. We find such simple scaling formulae are valid at low metallicities but not at all at high metallicities near and above solar. Thus, it is essential to use the isochrones rigorously computed for α-enhancement when modeling metal-rich populations, such as bright galaxies. The isochrone tables, together with interpolation routines have been made available via internet.

Short-Sale Constraints, Differences of Opinion, and Overvaluation

Abstract: Miller (1977) hypothesizes that dispersion of investor opinion in the presence of short-sale constraints leads to stock price overvaluation. However, previous empirical tests of Miller's hypothesis examine the valuation effects of only one of these two necessary conditions. We examine the valuation effects of the interaction between differences of opinion and short sale constraints. We find robust evidence of significant overvaluation for stocks that are subject to both conditions simultaneously. Stocks are not systematically overvalued when either one of these two conditions is not met.

Model atmospheres of very low mass stars and brown dwarfs

Abstract: ▪ Abstract As progressively cooler stellar and substellar objects are discovered, the presence first of molecules and then of condensed particulates greatly complicates the understanding of their physical properties. Accurate model atmospheres that include these processes are the key to establishing their atmospheric parameters. They play a crucial role in determining structural characteristics by setting the surface conditions of model interiors and providing transformations to the various observational planes. They can reveal the spectroscopic properties of brown dwarfs and help establish their detectability. In this paper, we review the current state-of-the-art theory and modeling of the atmospheres of very low mass stars, including the coolest known M dwarfs, M subdwarfs, and brown dwarfs, i.e. Teff ≤ 4,000 K and −4.0 ≤ [M/H] ≤ +0.0. We discuss ongoing efforts to incorporate molecular and grain opacities in cool stellar spectra, as well as the latest progress in (a) deriving the effective temperature ...

Small-Firm Performance: Modeling the Role of Product and Process Improvements*

Abstract: Entrepreneurial and small and medium-sized enterprises (SMEs) firm performance is a complex, multifaceted construct that should be examined with an eye toward its complexity. Our research study seeks to accomplish this examination by proposing a conceptual model of SME performance with two distinct but related outcome dimensions--growth as one dimension and profitability as another. We propose hypotheses for relationships between four antecedent factor conditions--environmental hostility, firm size, innovation capability, and internationalization--and an SME's likelihood to pursue either product improvement or process improvement as their primary strategic orientation. Furthermore, we propose that an SME product improvement orientation likely has greater influence on growth and profit performance than will a process improvement orientation. The findings of the study suggest that internationalization and innovator position have a positive impact on new product and process improvements, while environmental hostility, internationalization, and product improvement have positive influences on growth as a performance dimension. In addition and as hypothesized, the product improvement orientation is positively associated with growth and in turn profitability, whereas the process improvement orientation showed no statistical relationship to growth and ultimately profitability. Introduction An important subset of the small- and medium-sized enterprise (SME) and entrepreneurship literature is that which examines venture-related performance and the various antecedent factors and conditions thought to affect firm performance. Through this examination, researchers hope to provide SME managers and entrepreneurs some guidance with respect to successful venture performance. Researchers have found solid support for the effects of market attractiveness and resource-based capabilities on performance (Chandler and Hanks 1994). Covin and Covin (1990) found counterintuitive relationships among the level of competitive aggressiveness, environmental context, and the ultimate performance of small firms. Zahra and George (2000) revealed a strong association between commercialization capability, establishment of a reputation for quality, and SME technology firm sales growth. Also, innovation has demonstrated a strong and influential relationship with SME performance (Verhees and Meulenberg 2004; Qian and Li 2003). By their numbers alone, SMEs and entrepreneurial firms are a key segment and driver for most (if not all) national economies. Understanding how SMEs achieve high performance has significant implications for SME owners/managers, SME employees, and the economies in which the SME operates. High levels of performance can facilitate firm growth and subsequent profit performance, which in turn can yield employment gains and contribute to the general economic health of a state, region, or nation. Conversely, low performance may lead to firm stagnation or failure, and the negative economic ramifications commensurate with these outcomes. Given the resource constraints of small firms (Acs 1999) and their susceptibility to distress, hardship, and outright failure with respect to environment change and uncertainty, a better understanding of the contributing factors and mechanisms for high performance is desirable. The goal of this study was to expand our understanding of the factors contributing to firm performance by examining a set of related conditions and actions that we propose are of consequence to high SME performance. Our empirical research paper examines two characteristics of entrepreneurial SMEs--innovator position and the propensity to internationalize--in conjunction with two contextual variables (environmental hostility and firm size). We propose hypotheses for relationships between the four factors mentioned, and an SME's likelihood to pursue either product improvement or process improvement as their primary strategic orientation. …