Showing papers by "University of Texas at Austin published in 1999"

Data Envelopment Analysis: A Comprehensive Text with Models, Applications, References and DEA-Solver Software

Abstract: List of Tables. List of Figures. Preface. 1. General Discussion. 2. The Basic CCR Model. 3. The CCR Model and Production Correspondence. 4. Alternative DEA Models. 5. Returns to Scale. 6. Models with Restricted Multipliers. 7. Discretionary, Non-Discretionary and Categorical Variables. 8. Allocation Models. 9. Data Variations. Appendices. Index.

4-manifolds and Kirby calculus

Abstract: 4-manifolds: Introduction Surfaces in 4-manifolds Complex surfaces Kirby calculus: Handelbodies and Kirby diagrams Kirby calculus More examples Applications: Branched covers and resolutions Elliptic and Lefschetz fibrations Cobordisms, $h$-cobordisms and exotic ${\mathbb{R}}^{4,}$s Symplectic 4-manifolds Stein surfaces Appendices: Solutions Notation, important figures Bibliography Index.

Forming a story: The health benefits of narrative

Abstract: Writing about important personal experiences in an emotional way for as little as 15 minutes over the course of three days brings about improvements in mental and physical health. This finding has been replicated across age, gender, culture, social class, and personality type. Using a text-analysis computer program, it was discovered that those who benefit maximally from writing tend to use a high number of positive-emotion words, a moderate amount of negative-emotion words, and increase their use of cognitive words over the days of writing. These findings suggest that the formation of a narrative is critical and is an indicator of good mental and physical health. Ongoing studies suggest that writing serves the function of organizing complex emotional experiences. Implications for these findings for psychotherapy are briefly discussed. © 1999 John Wiley & Sons, Inc. J Clin Psychol 55: 1243–1254, 1999.

Content-Based Book Recommending Using Learning for Text Categorization

Abstract: Recommender systems improve access to relevant products and information by making personalized suggestions based on previous examples of a user's likes and dislikes. Most existing recommender systems use social filtering methods that base recommendations on other users' preferences. By contrast, content-based methods use information about an item itself to make suggestions. This approach has the advantage of being able to recommended previously unrated items to users with unique interests and to provide explanations for its recommendations. We describe a content-based book recommending system that utilizes information extraction and a machine-learning algorithm for text categorization. Initial experimental results demonstrate that this approach can produce accurate recommendations.

Scheduling multithreaded computations by work stealing

Abstract: This paper studies the problem of efficiently schedulling fully strict (i.e., well-structured) multithreaded computations on parallel computers. A popular and practical method of scheduling this kind of dynamic MIMD-style computation is “work stealing,” in which processors needing work steal computational threads from other processors. In this paper, we give the first provably good work-stealing scheduler for multithreaded computations with dependencies.Specifically, our analysis shows that the expected time to execute a fully strict computation on P processors using our work-stealing scheduler is T1/P + O(T ∞ , where T1 is the minimum serial execution time of the multithreaded computation and (T ∞ is the minimum execution time with an infinite number of processors. Moreover, the space required by the execution is at most S1P, where S1 is the minimum serial space requirement. We also show that the expected total communication of the algorithm is at most O(PT ∞( 1 + nd)Smax), where Smax is the size of the largest activation record of any thread and nd is the maximum number of times that any thread synchronizes with its parent. This communication bound justifies the folk wisdom that work-stealing schedulers are more communication efficient than their work-sharing counterparts. All three of these bounds are existentially optimal to within a constant factor.

Molecular mechanistic origin of the toughness of natural adhesives, fibres and composites

Abstract: Natural materials are renowned for their strength and toughness1,2,3,4,5. Spider dragline silk has a breakage energy per unit weight two orders of magnitude greater than high tensile steel1,6, and is representative of many other strong natural fibres3,7,8. The abalone shell, a composite of calcium carbonate plates sandwiched between organic material, is 3,000 times more fracture resistant than a single crystal of the pure mineral4,5. The organic component, comprising just a few per cent of the composite by weight9, is thought to hold the key to nacre's fracture toughness10,11. Ceramics laminated with organic material are more fracture resistant than non-laminated ceramics11,12, but synthetic materials made of interlocking ceramic tablets bound by a few weight per cent of ordinary adhesives do not have a toughness comparable to nacre13. We believe that the key to nacre's fracture resistance resides in the polymer adhesive, and here we reveal the properties of this adhesive by using the atomic force microscope14 to stretch the organic molecules exposed on the surface of freshly cleaved nacre. The adhesive fibres elongate in a stepwise manner as folded domains or loops are pulled open. The elongation events occur for forces of a few hundred piconewtons, which are smaller than the forces of over a nanonewton required to break the polymer backbone in the threads. We suggest that this ‘modular’ elongation mechanism might prove to be quite general for conveying toughness to natural fibres and adhesives, and we predict that it might be found also in dragline silk.

Marketing, Business Processes, and Shareholder Value: An Organizationally Embedded View of Marketing Activities and the Discipline of Marketing

Abstract: The authors develop a framework for understanding the integration of marketing with business processes and shareholder value. The framework redefines marketing phenomena as embedded in three core b...

Statistical inference in nonparametric frontier models: the state of the art

Abstract: Efficiency scores of firms are measured by their distance to an estimated production frontier. The economic literature proposes several nonparametric frontier estimators based on the idea of enveloping the data (FDH and DEA-type estimators). Many have claimed that FDH and DEA techniques are non-statistical, as opposed to econometric approaches where particular parametric expressions are posited to model the frontier. We can now define a statistical model allowing determination of the statistical properties of the nonparametric estimators in the multi-output and multi-input case. New results provide the asymptotic sampling distribution of the FDH estimator in a multivariate setting and of the DEA estimator in the bivariate case. Sampling distributions may also be approximated by bootstrap distributions in very general situations. Consequently, statistical inference based on DEA/FDH-type estimators is now possible. These techniques allow correction for the bias of the efficiency estimators and estimation of confidence intervals for the efficiency measures. This paper summarizes the results which are now available, and provides a brief guide to the existing literature. Emphasizing the role of hypotheses and inference, we show how the results can be used or adapted for practical purposes.

Collaboration in the Boardroom: Behavioral and Performance Consequences of CEO-Board Social Ties

Abstract: Empirical research has typically rested on the assumption that board independence from management enhances board effectiveness in administering firms The present study shows how and when a lack of social independence can increase board involvement and firm performance by raising the frequency of advice and counsel interactions between CEOs and outside directors Hypotheses were tested with original survey data from 243 CEOs and 564 outside directors on behavioral processes and dynamics in management-board relationships

Drift waves and transport

Abstract: Drift waves occur universally in magnetized plasmas producing the dominant mechanism for the transport of particles, energy and momentum across magnetic field lines. A wealth of information obtained from quasistationary laboratory experiments for plasma confinement is reviewed for drift waves driven unstable by density gradients, temperature gradients and trapped particle effects. The modern understanding of Bohm transport and the role of sheared flows and magnetic shear in reducing the transport to the gyro-Bohm rate are explained and illustrated with large scale computer simulations. The types of mixed wave and vortex turbulence spontaneously generated in nonuniform plasmas are derived with reduced magnetized fluid descriptions. The types of theoretical descriptions reviewed include weak turbulence theory, Kolmogorov anisotropic spectral indices, and the mixing length. A number of standard turbulent diffusivity formulas are given for the various space-time scales of the drift-wave turbulent mixing.

The evolution of Crew Resource Management training in commercial aviation.

Abstract: In this study, we describe changes in the nature of Crew Resource Management (CRM) training in commercial aviation, including its shift from cockpit to crew resource management. Validation of the impact of CRM is discussed. Limitations of CRM, including lack of cross-cultural generality are considered. An overarching framework that stresses error management to increase acceptance of CRM concepts is presented. The error management approach defines behavioral strategies taught in CRM as error countermeasures that are employed to avoid error, to trap errors committed, and to mitigate the consequences of error.

Development of a Functional Basis for Design

Abstract: Functional models represent a form independent blueprint of a product. As with any blueprint or schematic, a consistent language or coding system is required to ensure others can read it. This paper introduces such a design language, called a functional basis, where product function is characterized in a verb-object (function-flow) format. The set of functions and flows is intended to comprehensively describe the mechanical design space, Clear definitions are provided for each function and flow. The functional basis is compared to previous functional representations and is shown to subsume these attempts as well as offer a more consistent classification scheme. Applications to the areas of product architecture development, function structure generation, and design information archival and transmittal are discussed.

Elastography: ultrasonic estimation and imaging of the elastic properties of tissues.

Abstract: The basic principles of using sonographic techniques for imaging the elastic properties of tissues are described, with particular emphasis on elastography. After some preliminaries that describe some basic tissue stiffness measurements and some contrast transfer limitations of strain images are presented, four types of elastograms are described, which include axial strain, lateral strain, modulus and Poisson's ratio elastograms. The strain filter formalism and its utility in understanding the noise performance of the elastographic process is then given, as well as its use for various image improvements. After discussing some main classes of elastographic artefacts, the paper concludes with recent results of tissue elastography in vitro and in vivo.

Pml Is Critical for Nd10 Formation and Recruits the Pml-Interacting Protein Daxx to This Nuclear Structure When Modified by Sumo-1

Abstract: Nuclear domain 10 (ND10), also referred to as nuclear bodies, are discrete interchromosomal accumulations of several proteins including promyelocytic leukemia protein (PML) and Sp100. In this study, we investigated the mechanism of ND10 assembly by identifying proteins that are essential for this process using cells lines that lack individual ND10-associated proteins. We identified the adapter protein Daxx and BML, the RecQ helicase missing in Bloom syndrome, as new ND10-associated proteins. PML, but not BLM or Sp100, was found to be responsible for the proper localization of all other ND10-associated proteins since they are dispersed in PML−/− cells. Introducing PML into this cell line by transient expression or fusion with PML-producing cells recruited ND10-associated proteins into de novo formed ND10 attesting to PMLs essential nature in ND10 formation. In the absence of PML, Daxx is highly enriched in condensed chromatin. Its recruitment to ND10 from condensed chromatin requires a small ubiquitin-related modifier (SUMO-1) modification of PML and reflects the interaction between the COOH-terminal domain of Daxx and PML. The segregation of Daxx from condensed chromatin in the absence of PML to ND10 by increased accumulation of SUMO-1–modified PML suggests the presence of a variable equilibrium between these two nuclear sites. Our findings identify the basic requirements for ND10 formation and suggest a dynamic mechanism for protein recruitment to these nuclear domains controlled by the SUMO-1 modification state of PML.

Variability of apatite fission-track annealing kinetics: III. Extrapolation to geological time scales

Abstract: A new model for examining fission-track data from natural specimens has been developed on the basis of new laboratory data describing fission-track annealing in a wide variety of apatites and the empirical correction for fission-track length anisotropy presented in earlier papers. Using revised and simplified statistical methods, we examine how well various empirical equations are able to fit the laboratory data and reproduce expected behavior on geological time scales. Based on the latter criterion, we find that so-called "fanning Arrhenius" models of mean track length are not the best-suited for our data. Instead, we find that fitting c-axis projected lengths with a model that incorporates some curvature on an Arrhenius plot produces results that are in better agreement with the available geological benchmarks. In examining the relative annealing behavior of apatites with different resistance to annealing, we find that the laboratory-time-scale behavior of any two apatites can be reproduced well by a simple one- or two-parameter equation. This function is used to convert the reduced fission-track length of one apatite that has undergone a certain time-temperature history into the length that would be measured in a second, less-resistant apatite that has undergone the same history. Using this conversion, we create a single model that encompasses the annealing behavior of all of the apatites we studied. The predictions made by this model match closely those made by fits to data for individual apatites. We therefore infer that, although the conversion equation is imperfect, it presents an excellent practical solution to characterizing the range of kinetic variability for annealing of fission tracks in apatite.

Wave-packet dynamics in slowly perturbed crystals: Gradient corrections and Berry-phase effects

Abstract: We present a unified theory for wave-packet dynamics of electrons in crystals subject to perturbations varying slowly in space and time. We derive the wave-packet energy up to the first-order gradient correction and obtain all kinds of Berry phase terms for the semiclassical dynamics and the quantization rule. For electromagnetic perturbations, we recover the orbital magnetization energy and the anomalous velocity purely within a single-band picture without invoking interband couplings. For deformations in crystals, besides a deformation potential, we obtain a Berry-phase term in the Lagrangian due to lattice tracking, which gives rise to new terms in the expressions for the wave-packet velocity and the semiclassical force. For multiple-valued displacement fields surrounding dislocations, this term manifests as a Berry phase, which we show to be proportional to the Burgers vector around each dislocation.

Religious involvement and U.S. adult mortality

Abstract: We use recently released, nationally representative data from the National Health Interview Survey—Multiple Cause of Death linked file to model the association of religious attendance and sociodemographic, health, and behavioral correlates with overall and cause-specific mortality Religious attendance is associated with US adult mortality in a graded fashion: People who never attend exhibit 187 times the risk of death in the follow-up period compared with people who attend more than once a week This translates into a seven-year difference in life expectancy at age 20 between those who never attend and those who attend more than once a week Health selectivity is responsible for a portion of the religious attendance effect: People who do not attend church or religious services are also more likely to be unhealthy and, conse-quently, to die However, religious attendance also works through increased social ties and behavioral factors to decrease the risks of death And although the magnitude of the association between religious attendance and mortality varies by cause of death, the direction of the association is consistent across causes

Efficient folding of proteins with multiple disulfide bonds in the Escherichia coli cytoplasm

Abstract: Under physiological conditions, the Escherichia coli cytoplasm is maintained in a reduced state that strongly disfavors the formation of stable disulfide bonds in proteins. However, mutants in which the reduction of both thioredoxins and glutathione is impaired (trxB gor mutants) accumulate oxidized, enzymatically active alkaline phosphatase in the cytoplasm. These mutants grow very poorly in the absence of an exogenous reductant and accumulate extragenic suppressors at a high frequency. One such suppressor strain, FA113, grows almost as rapidly as the wild type in the absence of reductant, exhibits slightly faster kinetics of disulfide bond formation, and has fully induced activity of the transcriptional activator, OxyR. FA113 gave substantially higher yields of properly oxidized proteins compared with wild-type or trxB mutant strains. For polypeptides with very complex patterns of disulfide bonds, such as vtPA and the full-length tPA, the amount of active protein was further enhanced up to 15-fold by co-expression of TrxA (thioredoxin 1) mutants with different redox potentials, or 20-fold by the protein disulfide isomerase, DsbC. Remarkably, higher yields of oxidized, biologically active proteins were obtained by expression in the cytoplasm of E. coli FA113 compared with what could be achieved via secretion into the periplasm of a wild-type strain, even under optimized conditions. These results demonstrate that the cytoplasm can be rendered sufficiently oxidizing to allow efficient formation of native disulfide bonds without compromising cell viability.

Economic Preferences or Attitude Expressions?: An Analysis of Dollar Responses to Public Issues

Abstract: Participants in contingent valuation surveys and jurors setting punitive damages in civil trials provide answers denominated in dollars. These answers are better understood as expressions of attitudes than as indications of economic preferences. Well-established characteristics of attitudes and of the core process of affective valuation explain several robust features of dollar responses: high correlations with other measures of attractiveness or aversiveness, insensitivity to scope, preference reversals, and the high variability of dollar responses relative to other measures of the same attitude.

Language Anxiety: Differentiating Writing and Speaking Components

Abstract: This study investigated the links between second language classroom anxiety and second language writing anxiety as well as their associations with second language speaking and writing achievement. The results indicate that second language classroom anxiety, operationalized by Horwitz, Horwitz, and Cope's Foreign Language Classroom Anxiety Scale, and second language writing anxiety, measured by a modified second language version of Daly and Miller's Writing Apprehension Test, are two related but independent constructs. The findings suggest that second language classroom anxiety is a more general type of anxietyabout learning a second language with a strong speaking anxiety element, whereas second language writing anxiety is a language-skill-specific anxiety. Nevertheless, low self-confidence seems to be an important component of both anxiety constructs.

Recent developments and current controversies in the sociology of religion

Abstract: The sociology of religion is experiencing a period of substantial organizational and intellectual growth. Recent theoretical and empirical papers on the sociology of religion appearing in top journals in sociology have generated both interest and controversy. We begin with a selective overview of research on religious beliefs and commitments. Second, we investigate the influence of religion on politics, the family, health and well-being, and on free space and social capital. Finally, we review rational choice theories in the sociology of religion and the controversies surrounding applications of these perspectives.

Foreign Language Reading Anxiety

Abstract: Whereas most discussions of foreign language (FL) anxiety have centered on the difficulties caused by anxiety with respect to oral performance, this article discusses the possibility of anxiety in response to foreign or second language reading. It introduces the construct of FL reading anxiety, offers a scale for its measurement, and reports on a preliminary study of reading anxiety in 30 intact first-semester classes of Spanish, Russian, and Japanese. The study found that contrary to previous teacher intuitions, reading in a FL can be anxiety provoking to some students. Whereas general FL anxiety has been found to be independent of target language, levels of reading anxiety were found to vary by target language and seem to be related to the specific writing systems. In addition, students’ reading anxiety levels increased with their perceptions of the difficulty of reading in their FL, and their grades decreased in conjunction with their levels of reading anxiety and general FL anxiety.

Step and flash imprint lithography: a new approach to high-resolution patterning

Abstract: An alternative approach to lithography is being developed based on a dual-layer imprint scheme. This process has the potential to become a high-throughput means of producing high aspect ratio, high-resolution patterns without projection optics. In this process, a template is created on a standard mask blank by using the patterned chromium as an etch mask to produce high-resolution relief images in the quartz. The etched template and a substrate that has been coated with an organic planarization layer are brought into close proximity. A low-viscosity, photopolymerizable formulation containing organosilicon precursors is introduced into the gap between the two surfaces. The template is then brought into contact with the substrate. The solution that is trapped in the relief structures of the template is photopolymerized by exposure through the backside of the quartz template. The template is separated from the substrate, leaving a UV-curved replica of the relief structure on the planarization layer. Features smaller than 60 nm in size have been reliably produced using this imprinting process. The resolution silicon polymer images are transferred through the planarization layer by anisotropic oxygen reactive ion etching. This paper provides a progress report on our efforts to evaluate the potential of this process.

RAM: A Range Adjusted Measure of Inefficiency for Use with Additive Models, and Relations to Other Models and Measures in DEA

Abstract: Generalized Efficiency Measures (GEMS) for use in DEA are developed and analyzed in a context of differing models where they might be employed. The additive model of DEA is accorded a central role and developed in association with a new measure of efficiency referred to as RAM (Range Adjusted Measure). The need for separately treating input oriented and output oriented approaches to efficient measurement is eliminated because additive models effect their evaluations by maximizing distance from the efficient frontier (in l1, or weighted l1, measure) and thereby simultaneously maximize outputs and minimize inputs. Contacts with other models and approaches are maintained with theorems and accompanying proofs to ensure the validity of the thus identified relations. New criteria are supplied, both managerial and mathematical, for evaluating proposed measures. The concept of “approximating models” is used to further extend these possibilities. The focus of the paper is on the “physical” aspects of performance involved in “technical” and “mix” inefficiencies. However, an Appendix shows how “overall,” “allocative” and “technical” inefficiencies may be incorporated in additive models.