Showing papers by "University of Texas at Arlington published in 1994"

The influence of store environment on quality inferences and store image

Abstract: The study reported here examines how combinations of specific elements in the retail store environment influence consumers’ inferences about merchandise and service quality and discusses the extent to which these inferences mediate the influence of the store environment on store image. Results show that ambient and social elements in the store environment provide cues that consumers use for their quality inferences. In addition, store environment, merchandise quality, and service quality were posited to be antecedents of store image—with the latter two serving as mediators—rather than components of store image (as they are typically treated in the store image literature). Theoretical and managerial implications of the findings are discussed, and future research directions are proposed.

Bactericidal Activity of TiO2 Photocatalyst in Aqueous Media: Toward a Solar-Assisted Water Disinfection System.

Abstract: Irradiation of suspensions of Escherichia coli ([approximately] 10[sup 6] cells/mL) and TiO[sub 2] (anatase) with UV-visible light of wave-lengths longer than 380 nm resulted in the killing of the bacteria within minutes. Oxygen was found to be a prerequisite for the bactericidal properties of the photocatalyst. Bacterial killing was found to adhere to first-order kinetics. The rate constant was proportional to the square root of the concentration of TiO[sub 2] and proportional to the incident light intensity in the range [approximately] 180- [approximately] 1660 [mu]E s[sup [minus]1] m[sup [minus]2]. The trends in these simulated laboratory experiments were mimicked by outdoor tests conducted under the summer noonday sun in Texas. The implications of these results as well as those of previous investigations in terms of practical applicability to solar-assisted water treatment and disinfection at remote sites are discussed relative to water technologies currently considered as viable as alternatives to chlorination. 24 refs., 8 figs.

Electrochemistry and the environment

Abstract: Advances in electrochemical methods for pollutant remediation, recycling and sensing are reviewed. Additionally, applications of these methods in the drinking water industry, and for disinfection scenarios are discussed. Lastly, new electrode materials for environmental applications are described. In a companion review, photoelectrochemical methods will be discussed.

Substructure discovery in the SUBDUE system

Abstract: Because many databases contain or can be embellished with structural information, a method for identifying interesting and repetitive substructures is an essential component to discovering knowledge in such databases. This paper describes the SUBDUE system, which uses the minimum description length (MDL) principle to discover substructures that compress the database and represent structural concepts in the data. By replacing previously-discovered substructures in the data, multiple passes of SUBDUE produce a hierarchical description of the structural regularities in the data. Inclusion of background knowledge guides SUBDUE toward appropriate substructures for a particular domain or discovery goal, and the use of an inexact graph match allows a controlled amount of deviations in the instance of a substructure concept. We describe the application of SUBDUE to a variety of domains. We also discuss approaches to combining SUBDUE with non-structural discovery systems.

Variation of Geometric Invariant Theory Quotients

Abstract: Geometric Invariant Theory gives a method for constructing quotients for group actions on algebraic varieties which in many cases appear as moduli spaces parametrizing isomorphism classes of geometric objects (vector bundles, polarized varieties, etc.). The quotient depends on a choice of an ample linearized line bundle. Two choices are equivalent if they give rise to identical quotients. A priori, there are infinitely many choices since there are infinitely many isomorphism classes of linearized ample line bundles. Hence several fundamental questions naturally arise. Is the set of equivalence classes, and hence the set of non-isomorphic quotients, finite? How does the quotient vary under change of the equivalence class? In this paper we give partial answers to these questions in the case of actions of reductive algebraic groups on nonsingular projective algebraic varieties. We shall show that among ample line bundles which give projective geometric quotients there are only finitely many equivalence classes. These classes span certain convex subsets (chambers) in a certain convex cone in Euclidean space; and when we cross a wall separating one chamber from another, the corresponding quotient undergoes a birational transformation which is similar to a Mori flip.

The DØ detector

Abstract: The DO detector is a large general purpose detector for the study of short-distance phenomena in high energy antiproton-proton collisions, now in operation at the Fermilab Tevatron collider. The detector focusses upon the detection of electrons, muons, jets and missing transverse momentum. We describe the design and performance of the major elements of the detector, including the tracking chambers, transition radiation detector, liquid argon calorimetry and muon detection. The associated electronics, triggering systems and data acquisition systems are presented. The global mechanical, high voltage, and experiment monitoring and control systems which support the detector are described. We also discuss the design and implementation of software and software support systems that are specific to DO.

Design of waveguide-grating filters with symmetrical line shapes and low sidebands.

Abstract: We show that ideal reflection filters can be designed by combining guided-mode resonance effects in waveguide gratings with antireflection effects of thin-film structures. Since the guided-mode resonance effect overrides the antireflection effect this filter provides a symmetrical line shape with near-zero reflectivity over appreciable wavelength bands adjacent to the resonance wavelength. In the single-layer filter the same layer functions as the waveguide grating supporting the resonance and as the antireflection layer suppressing reflection around the resonance. A multilayer design allows the filter resonance peak to have a wide surrounding region of low reflectance. The central resonance wavelength, the filter linewidth, the range of the low sidebands, and the resonance line shape are all under the control of the designer.

A cognitive interpretation of transactional and transformational leadership theories

Abstract: Cognitive processes constructs provide a framework for analysis of transformational leadership and transactional leadership behaviors. Working memory, attribution, expectation, schema, script, and strategy processes are viewed as mediators in the relationships between feedback and environmental inputs and leadership behaviors. While these processes are the bases for both transformational and transactional leadership behaviors, the specific cognitive content differs between them. Whether an individual leads by developing a vision and enlisting subordinates' ego involvement in it or by setting goals and structuring tasks, depends upon the content of relevant schemata and scripts. This content is developed through experiences in similar situations or through vicarious learning. Literature relevant to the leadership and cognitive processes areas is reviewed, propositions are presented, and implications for research and practice are discussed.

Feedback linearization using neural networks

Abstract: For a class of single-input, single-output (SISO), continuous-time nonlinear systems, a neural network-based controller is presented that feedback linearizes the system. Control action is used to achieve tracking performance for a state-feedback linearizable, but unknown nonlinear system. A global stability proof is given in the sense of Lyapunov. It is shown that all the signals in the closed-loop system and the control action are GUUB. No learning phase requirement is needed and initialisation of the network is straightforward. >

Effect of Foreclosure Status on Residential Selling Price

Abstract: Real estate professionals believe that foreclosed houses sell at a discount. This article empirically investigates whether foreclosed houses sell at a discount. A sample of 2,482 residential transa...

Comparative examinations of self-reports and perceived absenteeism norms: Wading through Lake Wobegon.

Abstract: The properties of self-reports and perceived norms of absenteeism were examined and compared in 7 progressive studies. Regardless of attendance context, time interval, type of estimate, or administration condition, individuals reported (on average) having roughly half the absenteeism of the perceived norm among their peers; 85% to 95% of respondents reported being above average in their attendance record. This «Lake Wobegon effect» was traced to a small negative bias (underreporting) in self-reports and a large positive bias (overreporting) in perceived norms. Self-presentation and availability processes were proposed as explanations for these biases. In a study in which direct observations of past and future absenteeism were collected, self-reports correlated.69 (p <.01) with the direct observations. Perceived norms explained unique variation (ΔR 2 =.10, p <.01) in future absenteeism

Flexible-link robot arm control by a feedback linearization/singular perturbation approach

Abstract: A nonlinear tracking controller for the link-tip positions and velocities of a multi-link flexible robot arm is designed that gives guaranteed performance. The controller has three parts: a model-based trajectory generator, an inner loop based on input-output feedback linearization, and an outer loop that stabilizes the internal dynamics (e.g., the flexible modes) using a singular perturbation design. We show how to stabilize the internal dynamics by selecting a physically meaningful modified performance output for tracking; this output is the slow portion of the link-tip motions. That is, the tracking requirement is relaxed so that the internal dynamics are stabilizable through a boundary layer correction that attenuates the flexible mode vibrations. © 1994 John Wiley & Sons, Inc.

Valuation effects of international stock exchange listings

Abstract: A comprehensive data set consisting of 346 U.S. firm stock listings on ten different stock exchanges is examined in order to determine the valuation consequences of listing on a foreign stock exchange. For the sample of U.S. firms listing abroad, abnormal returns in U.S. trading were: (1) positive around the date of acceptance on the foreign exchange; (2) negative on the first trading day; and (3) negative in the post-listing period for firms listing on the Tokyo and Basel exchanges. Tests for the equality of stock return variances between event periods and market model estimation periods failed to reveal a definitive impact.

Exploring strategic judgment: Methods for testing the assumptions of prescriptive contingency theories

Abstract: Several generally untested assumptions about strategic judgment and choice exist in strategic management theories. Direct examination of these assumptions is necessary for sound theory building, and for sound prescription based on current theory. This paper presents techniques for eliciting and analyzing the strategic judgments of strategy makers, and discusses the potential of these techniques for increasing the internal validity and practical relevance of strategy research. We argue that incorporating managerial judgment more directly into the mainstream of strategy research will lead to both new theory and the extension of existing theory.

On object state testing

Abstract: The importance of object state testing is illustrated through a simple example. We show that certain errors in the implementation of object state behavior cannot be readily detected by conventional structural testing, functional testing, and state testing. We describe an object state test model and outline a reverse engineering method for extracting object state behaviors from C++ source code. The object state test model is a hierarchical, concurrent, communicating state machine. It resembles the concepts of inheritance and aggregation in the object-oriented paradigm rather than the concept of state decomposition as in some existing models. The reverse engineering method is based on symbolic execution to extract the states and effects of the member functions. The symbolic execution results are used to construct the state machines. The usefulness of the model and of the method is discussed in the context of object state testing in the detection of a state behavior error. >

Towards an infrastructure for temporal databases: report of an invitational ARPA/NSF workshop

Abstract: the discussion. Specifically, an initial glossary of temporal database concepts and a. test suite of temporal queries were distributed before the workshop. Both of these document*s were amended based on the analysis and critique of the workshop. A language design committee was constituted after the workshop to develop a consensus temporal query la,nguage extension to SQL-92; this design also benefited from the discussion at the workshop. This report documents the discussions and consensus reached at the workshop. The report. reflects the conclusions rea.ched at the workshop in June, 1993 and further discussions amongst the group participants through electronic mail. In preparing this report, each group coordinator assembled ideas and prepared an initial draft, which was then reviewed by a.11 the workshop participants. The record of the deliberations of these four groups, in the following four sections, forms t.he bulk of this report. Each of these sections begins with the group’s charter and a brief snapshot of the status of the field and ends with a list of follow-on efforts. The last, section identifies the workshop pa.rticipants. The full report’ provides more discussion and many additional references t,o the literature.

Attachment of two electrons to C60F48: Coulomb barriers in doubly charged anions.

Abstract: The highly fluorinated chiral [ital C][sub 3[ital h]] molecule C[sub 60]F[sub 48] was observed to sequentially attach two electrons in the gas phase to produce C[sub 60]F[sub 48][sup 2[minus]] and C[sub 60]F[sub 46][sup 2[minus]]+F[sub 2]. The first electron affinity (EA) of C[sub 60]F[sub 48] was measured to be 4.06[plus minus]0.3 eV. The first and second EA were calculated to be EA[sub 1]=5.07 eV and EA[sub 2]=2.27 eV for the more symmetric [ital D][sub 3[ital d]] isomer. The dianion was found to be [ital more] [ital stable] with respect to electron detachment than the singly-charged anion. This remarkable stability of the dianion is attributed to a potential barrier resulting from the long range Coulomb repulsion and short range electron-molecule binding.

A dynamic learning neural network for remote sensing applications

Abstract: The neural network learning process is to adjust the network weights to adapt the selected training data. Based on the polynomial basis function (PBF) modeled neural network that is a modified multilayer perceptrons (MLP) network, a dynamic learning algorithm (DL) is proposed. The presented learning algorithm makes use of the Kalman filtering technique to update the network weights, in the sense that the stochastic characteristics of incoming data sets are implicitly incorporated into the network. The Kalman gains which represent the learning rates of the network weights updating are calculated by using the U-D factorization. By concatenating all of the network weights at each layer to form a long vector such that it can be updated without propagating back, the proposed algorithm improves the performance of convergence to which the backpropagation (BP) learning algorithm often suffers. Numerical illustrations are carried out using two categories of problems: multispectral imagery classification and surface parameters inversion. Results indicates the use of Kalman filtering algorithm not only substantially increases the convergence rate in the learning stage, but also enhances the separability for highly nonlinear boundaries problems, as compared to BP algorithm, suggesting that the proposed DL neural network provides a practical and potential tool for remote sensing applications. >

Unfastening the Electoral Connection: The Behavior of U.S. Representatives when Reelection Is No Longer a Factor

Abstract: While elections are essential to a democracy, it is commonly believed that the desire to secure reelection causes legislators to engage in many undesirable activities. In this note, by comparing the behavior of U.S. representatives who have chosen to run for reelection with those representatives who have decided not to do so, we provide evidence of the precise activities induced by electoral concerns. We find that elections cause members to go back to the district more often, to employ more staff assistants, to attend to roll-call voting more fastidiously, and to be more legislatively active. While these activities are no doubt consistent with the wishes of most constituents, the desire for reelection also encourage members to introduce what is apparently frivolous legislation on topics of little familiarity to the member. Those members who are not running for reelection, on the other hand, are more likely to have a successful and tightly focused legislative agenda.

Comparison of optical scattering experiments and the quasi-crystalline approximation for dense media

Abstract: The fractional volume dependence of the extinction rate in dense media is studied. Results from optical scattering experiments are compared with the theoretical extinction rate calculated by independent-scattering theory and the quasi-crystalline approximation (QCA). QCA takes into account the coherent interaction among scatterers in the vicinity of each other, as weighted by a pair distribution function. QCA is shown to be in good agreement with experimental data.