Showing papers by "University of Memphis published in 1996"

Is it an Agent, or Just a Program?: A Taxonomy for Autonomous Agents

Abstract: The advent of software agents gave rise to much discussion of just what such an agent is, and of how they differ from programs in general. Here we propose a formal definition of an autonomous agent which clearly distinguishes a software agent from just any program. We also offer the beginnings of a natural kinds taxonomy of autonomous agents, and discuss possibilities for further classification. Finally, we discuss subagents and multiagent systems.

The Management of Customer-Contact Service Employees: An Empirical Investigation:

Abstract: The authors develop and test a model of service employee management that examines constructs simultaneously across three interfaces of the service delivery process: manager-employee, employee-role,...

Key issues in information systems management: 1994–95 SIM Delphi results

Abstract: Over the past 15 years, the Society for Information Management (SIM) has periodically 1 Sirkka Jarvenpaa was the accepting senior editor for this paper. 2 Dr. Wetherbe is also FedEx Professor of Excellence at the University of Memphis. surveyed its members to determine the most critical issues in IS management. Again in 1994-95, SIM institutional and board members were asked to consider what they felt were the most critical issues facing IS executives over the next three to five years. Signaling an evolutionary shift in IS management, this study shows that business relationship issues have declined in importance compared to technology infrastructure issues. For IS executives and general managers, the key issue framework suggests some general directions for emphasis and provides a coarse measure for benchmarking their own concerns against those of their peers. The results of this study also impact educational missions in teaching and research to the extent that they need to be sensitive to the views of practicing fS executives.

Impact of corporate insider, blockholder, and institutional equity ownership on firm risk taking

Abstract: The nature of a firm's risk-taking behavior can significantly affect corporate performance. In an agency context, we examined the influence of equity ownership structure upon corporate risk taking....

Seismic moment assessment of earthquakes in stable continental regions—III. New Madrid 1811–1812, Charleston 1886 and Lisbon 1755

Abstract: SUMMARY The sizes of three major or great historical earthquakes are reassessed using the isoseismal-area-regression tools developed in Parts I and II of this study of stable continental region (SCR) seismicity. The earthquakes are 1811 New Madrid, central United States, and its following sequence; 1886 Charleston, coastal South Carolina; and 1755 Lisbon, oceanic intraplate off the continental shelf of Portugal. The analysis confirms the large size of these events and for the first time places constraints on the uncertainty of their seismic moment release. Because of the exceptionally low seismic-wave attenuation of eastern North America (ENA), a separate North American regression of seismic moment on isoseismal area was developed. Additionally, the unknown western extents of the New Madrid isoseismal areas were calibrated with the patterns of the M 6.3-6.6 1843 and 1895 earthquakes. Application of Part II analysis procedures with these corrections yields New Madrid size estimates, expressed as moment magnitude, of M 8.1±0.31 for the 1811 December 16, M 7.8±0.33 for the 1812 January 23, and M 8.0±0.33 for the 1812 February 7 principal events. The Charleston earthquake's magnitude decreases from M≳7.4 to M 7.3±0.26 after compensation for the effect of coastal plain sediments on its inner isoseismals. Intensity regressions for Lisbon are calibrated against the isoseismal pattern of the nearly co-located M 7.8 1969 St Vincent earthquake, which in this case increases the predicted size of Lisbon from M 8.4 to M 8.7±0.39. These size estimates are supported by data from independent phenomena: extent and severity of liquefaction, the maximum distance of induced landslides, and for Lisbon, tsunami wave amplitudes. Estimated source parameters are controlled by crustal or lithospheric temperature, which governs the depth extent of brittle faulting. Using estimated continental and oceanic geotherms, viable fault lengths are 30–80 km for Charleston, 120–180 km for 1811 New Madrid, and 180–280 km for Lisbon for average displacements of 2–4 m, 8–11 m, and 10–14 m, respectively, and for average static stress and strain drops. At the estimated seismic moments of this study, the 1811 New Madrid and the 1755 Lisbon events are, respectively, the largest known SCR and oceanic lithosphere earthquakes.

The Impact of Security Analysts' Monitoring and Marketing Functions on the Market Value of Firms

Abstract: In this study, we examine the impact of security analysts' monitoring and marketing functions on firms' market value. We postulate that security analysts' monitoring of corporate performance helps motivate managers, thus reducing the agency costs associated with the separation of ownership and control. We also argue that the information intermediary function provided by security analysts helps expand the breadth of investor cognizance. Consistent with these conjectures, this study finds that analyst following exerts a significant and positive impact on firms' market value. We also find evidence that security analysts have a stronger incentive to follow stocks of high quality companies, since such stocks arc easier to market. Hence, the security analysis activities appear to be determined, in part, by the marketing considerations of brokerage companies.

Seismic moment assessment of earthquakes in stable continental regions?I. Instrumental seismicity

Abstract: SUMMARY This Part I study, in conjunction with Part 11, develops a method to determine, within specified uncertainty bounds, the seismic moment, and thus moment magnitude, of all earthquakes of stable continental regions (SCR) for which instrumental or intensity data exist. Its basis is polynomial regression analysis using a database of SCR earthquakes with direct seismic moment determination. The independent variables include modern teleseismic magnitudes and regional magnitudes (Part I), and isoseismal areas or number of recording stations (Part 11). Part I11 is an application of the methodology of Parts I and I1 to several major historical earthquakes. All data used in the regressions are assigned individual uncertainties estimated from the literature or from experience; formal confidence limits (68 per cent or 95 per cent) on both the regression formulas and the predicted seismic moment values are then possible via error propagation analysis. The most complete development is for the teleseismic magnitudes M, and mb. For both, the final regression for log(M,) is a quadratic formula that closely emulates the relationship between amplitude magnitudes and log(M,) expected from dislocation theory and source-scaling arguments. Regressions are also derived for the regional magnitudes mLg and M,, because there are many SCR events, mainly pre- 1964, that have no teleseismic magnitudes. Prediction uncertainties from teleseismic magnitudes in moment magnitude units are in the AO.18-0.28 range, and from regional magnitudes in the kO.23-0.38 range over a wide magnitude band. Finally, the methodology developed here is generic, even though the database is specific. Application to plate-boundary, oceanic intraplate, or active continental intraplate regions should be straightforward.

How Civil Wars End A Rational Choice Approach

Abstract: What conditions determine whether a civil war ends in a negotiated settlement or a military victory? The authors address this question by developing an expected utility model of the choice between ...

Morphometry of the human pulmonary vasculature

Abstract: Huang, W., R. T. Yen, M. McLaurine, and G. Bledsoe.Morphometry of the human pulmonary vasculature.J. Appl. Physiol. 81(5): 2123–2133, 1996.—The morphometric data on the branching pattern and vascul...

Volume tracking of interfaces having surface tension in two and three dimensions

Abstract: Solution algorithms are presented for tracking interfaces with piecewise linear (PLIC) volume-of-fluid (VOF) methods on fixed (Eulerian) two-dimensional (2-D) structured and three-dimensional (3-D) structured and unstructured grids. We review the theory of volume tracking methods, derive appropriate volume evolution equations, identify and present solutions to the basic geometric functions needed for interface reconstruction and volume fluxing, and provide detailed algorithm templates for modern 2-D and 3-D PLIC VOF interface tracking methods. We discuss some key outstanding issues for PLIC VOF methods, namely the method used for time integration of fluid volumes (operator splitting, unsplit, Runge-Kutta, etc.) and the estimation of interface normals. We also present our latest developments in the continuum surface force (CSF) model for surface tension, namely extension to 3-D and variable surface tension effects. We identify and focus on key outstanding CSF model issues that become especially critical on fine meshes with high density ratio interfacial flows, namely the surface delta function approximation, the estimation of interfacial curvature, and the continuum surface force scaling and/or smoothing model. Numerical results in two and three dimensions are used to illustrate the properties of these methods.

The Development of Occupational Aspirations and Expectations among Inner‐City Boys

Abstract: The occupational aspirations and expectations of two populations of boys in grades 2, 4, 6, and 8 were examined in order (1) to describe what is unique about the development of job preferences among urban ghetto children who live in settings where many adult males are not well attached to the labor force and (2) to examine 6 reasons for any age- and population-dependent patterns there might be in job aspirations and job expectations. Findings show that boys tend to be more realistic about occupational aspirations and expectations the older they are; that from second grade on the occupational expectations of inner-city boys mirror existing race and class differences in adult job holdings; that the gap between occupational aspirations and expectations is greater for the ghetto boys and remains roughly constant in size across the grades examined; and that the lower occupational expectations of the inner-city boys are strongly related to their lower educational expectations, with these educational expectations being associated with fewer poor boys having a biological father at home and with more of these boys seeing obstacles to success in the local social setting. But, the lower occupational expectations of the ghetto boys are not due to having fewer positive role models or believing that schooling will not pay off for them in the future as it does for others.

The suitability of montane ecotones as indicators of global climatic change

Abstract: Because of the difficulties involved with separating natural fluctuations in climatic variables from possible directional changes related to human activities (e.g., heightened atmospheric CO2 concentrations related to fossil fuel consumption), some researchers have focused on developing alternative indicators to detect hypothesized climate changes. It has, for example, been suggested that the locations of ecotones, transitions between adjacent ecosystems or biomes, should be monitored. It is assumed that changes in climate, especially increases in atmospheric temperature, will result in shifts in the location (altitude or latitude) of ecotones as plants respond to the newly imposed climatic conditions. In this article, we address the use of two montane ecotones, the alpine tree-line ecotone and the deciduous/Boreal forest ecotone, in monitoring global climatic change. In so doing, we 1) outline the factors that create and maintain each ecotone's position at a given location; 2) assess the projected respon...

Changes in bone mineral content in male athletes. Mechanisms of action and intervention effects.

Abstract: Objectives. —To determine changes in bone mineral content (BMC) in male athletes, to examine the mechanisms of changes, and to evaluate the effects of intervention. Design. —Dual-energy x-ray absorptiometry (DEXA) tests were administered over a 2-year period, and calcium loss during training was determined by analysis of sweat and urine. Calcium supplementation was administered during year 2. Setting. —A midsouth university. Participants. —Eleven members of a college Division l-A basketball team. Intervention. —Based on observed calcium loss, athletes received differential levels of calcium supplementation. Intervention commenced the week prior to the fall training season and continued through postseason play. Main Outcome Measure. —Changes in BMC. Results. —Total body BMC decreased 3.8% from preseason to midseason of year 1 (meandecrease, 133.4g, P =.02), increasednonsignificantlyby 1.1%(mean increase, 35.3 g, P =.22) during the offseason, but decreased an additional 3.3% during summer months when practices resumed (mean decrease, 113.1 g, P =.01). Dermal calcium loss averaged 422 mg per training session. From preseason to late summer, there was an overall decrease of 6.1% in total BMC and a 10.5% decrease in BMC of the legs. Calcium supplementation was associated with significant increases in BMC and lean body mass. Conclusions. —Bone loss is calcium related and exercise is positively related to BMC provided that calcium intake is sufficient to offset dermal loss.

Sex differentiation of channel catfish gonads : normal development and effects of temperature

Abstract: Channel catfish have an XX female-XY male sex determination system. Although genetic males of this species are readily feminized with exogenous steroid, the pattern of gonadal sex differentiation and the effect of temperature on genetic sex determination are unknown. To document the pattern of gonadal sex differentiation, catfish from a mixed-sex progeny (XX female-XY made cross), known XY males (XX female-YY male cross), and steroid sex-reversed (XY) females were reared at 28°C and collected for histological analysis from Day 7 to Day 90 postfertilization. No signs of gonadal sex differentiation were detected from Day 7 to Day 16. On Day 19, about half the fish from the mixed-sex population as well as the sex-reversed females had gonads with proximal and distal tissue outgrowths. These outgrowths eventually fused to form an ovarian cavity. Germ cell meiosis in these gonads was first detected on Day 22 and growing ovarian follicles were seen at later stages. Thus, ovarian differentiation began about Day 19. Although presumptive testes lose their sensitivity to feminizing steroids about Day 19, the gonads of known males and of putative males from the mixed-sex population showed no clear signs of sex differentiation up to Day 90. Thus, the prolonged temporal dissociation between testicular commitment and differentiation indicates that these two events may be mediated by separate stimuli. To determine the effects of temperature on sex determination, fish of a mixed-sex population were reared at 27°C until Day 10; at 20°, 27°, or 34°C from Day 10 to Day 24; and then at 27°C until Day 102 when sex ratios and gonadal histology were determined. The sex ratio was significantly skewed toward females in fish treated at 34°C (1 male:1.68 female; P < 0.01) but no effects were seen at 20° or 27°C. This observation suggests that genetic and temperature-dependent mechanisms of sex determination are both functional in channel catfish and that this phenomenon is more widespread in fishes than previously believed. The testes of the Day 102 males examined had developed positive histological signs of sex differentiation, suggesting that testicular formation in channel catfish normally starts between Day 90 and 102. © 1996 Wiley-Liss, Inc.

WHO cross-cultural applicability research on diagnosis and assessment of substance use disorders: an overview of methods and selected results.

Abstract: The cross-cultural applicability of criteria for the diagnosis of substance use disorders and of instruments used for their assessment were studied in nine cultures. The qualitative and quantitative methods used in the study are described. Equivalents for English terms and concepts were found for all instrument items, diagnostic criteria, diagnoses and concepts, although often there was no single term equivalent to the English in the languages studied. Items assuming self-consciousness about feelings, and imputing causal relations, posed difficulties in several cultures. Single equivalent terms were lacking for some diagnostic criteria, and criteria were sometimes not readily differentiated from one another. Several criteria--narrowing of the drinking repertoire, time spent obtaining and using the drug, and tolerance for the drug--were less easy to use in cultures other than the United States. Thresholds for diagnosis used by clinicians often differed. In most cultures, clinicians were more likely to make a diagnosis of drug dependence than of alcohol dependence although behavioural signs were equivalent. The attitudes of societies to alcohol and drug use affects the use of criteria and the making of diagnoses.

Executive ownership, corporate value, and executive compensation: A unifying framework

Abstract: This study presents an integrated investigation into the factors affecting executive ownership, the market value of the firm, and executive compensation by explicitly incorporating the simultaneity of the process determining these variables into the empirical estimation. Overall, the results of the study support the notion that a firm's market value, executive stock ownership, and executive compensation are jointly determined. Further, the findings suggest that executive stock ownership and executive compensation may serve as a type of bond by which top executives are induced to act in the best interests of shareholders. The study also finds that a firm's q ratio and an executive's job-specific experience (as well as firm size) are important determinants of executive compensation. This result is generally consistent with the view that the firm optimally establishes its managerial compensation plan in response to both its operating environment and the specific personal characteristics of its chief executive(s).

Leaf gas exchange and growth of flood-tolerant and flood-sensitive tree species under low soil redox conditions

Abstract: Seedlings of Taxodium distichum L., Quercus lyrata Walt. and Q. falcata var. pagodaefolia Ell. were grown for 22 days in a rhizotron system providing two soil redox potential regimes, +170 mV (low Eh) and +560 mV (high Eh). Leaf chlorophyll concentration and gas exchange, root alcohol dehydrogenase (ADH) activity, root and leaf ethylene production, and growth and biomass partitioning were measured. In response to the low Eh soil treatment, stomatal conductance was reduced in Q. falcata and Q. lyrata but not in T. distichum, whereas net photosynthesis was reduced significantly in all species; however, net photosynthesis in T. distichum began to recover within 2 weeks of treatment initiation. Within each treatment, mean stomatal conductance and net photosynthesis were significantly greater in T. distichum than in the oak species. Leaf chlorophyll concentration was not affected by the soil treatments. All species showed significant reductions in root and leaf dry weights in response to the low Eh soil condition. The low Eh soil treatment resulted in increased root ADH activity and ethylene production in T. distichum, but had no effect on root ADH activity and ethylene production in the oak species.

Experimental Verification of the Importance of The Nonlinear Curvature in the Response of a Cantilever Beam

Abstract: An experimental and theoretical investigation into the first- and second-mode responses of a parametrically excited slender cantilever beam is presented. Inclusion of quadratic damping in the analytical model significantly improves the agreement between the experimental and theoretical results. In addition, the experimental results verify that the often ignored nonlinear curvature terms play a dominant role in the response of the first mode and that the nonlinear inertia terms play a dominant role in the response of the second mode.

An evaluation of empirical measures of source identification.

Abstract: Source identification refers to memory for the origin of information. A consistent nomenclature is introduced for empirical measures of source identification which are then mathematically analyzed and evaluated. The ability of the measures to assess source identification independently of identification of an item as old or new depends on assumptions made about how inconsistencies between the item and source components of a source-monitoring task may be resolved. In most circumstances, the empirical measure that is used most often when source identification is measured by collapsing across pairs of sources (sometimes called “the identification-of-origin score”) confounds item identification with source identification. Alternative empirical measures are identified that do not confound item and source identification in specified circumstances. None of the empirical measures examined provides a valid measure of source identification in all circumstances.

Clinical value of proton magnetic resonance spectroscopy for differentiating recurrent or residual brain tumor from delayed cerebral necrosis

Abstract: Purpose: Delayed cerebral necrosis (DN) is a significant risk for brain tumor patients treated with high-dose irradiation. Although differentiating DN from tumor progression is an important clinical question, the distinction cannot be made reliably by conventional imaging techniques. We undertook a pilot study to assess the ability of proton magnetic resonance spectroscopy ( 1 H MRS) to differentiate prospectively between DN or recurrent/residual tumor in a series of children treated for primary brain tumors with high-dose irradiation. Methods and Materials: Twelve children (ages 3–16 years), who had clinical and MR imaging (MRI) changes that suggested a diagnosis of either DN or progressive/recurrent brain tumor, underwent localized 1 H MRS prior to planned biopsy, resection, or other confirmatory histological procedure. Prospective 1 H MRS interpretations were based on comparison of spectral peak patterns and quantitative peak area values from normalized spectra: a marked depression of the intracellular metabolite peaks from choline, creatine, and N-acetyl compounds was hypothesized to indicate DN, and median-to-high choline with easily visible creatine metabolite peaks was labeled progressive/recurrent tumor. Subsequent histological studies identified the brain lesion as DN or recurrent/residual tumor. Results: The patient series included five cases of DN and seven recurrent/residual tumor cases, based on histology, The MRS criteria prospectively identified five out of seven patients with active tumor, and four out of five patients with histologically proven DN correctly. Discriminant analysis suggested that the primary diagnostic information for differentiating DN from tumor lay in the normalized MRS peak areas for choline and creatine compounds. Conclusions: Magnetic resonance spectroscopy shows promising sensitivity and selectivity for differentiating DN from recurrent/progressive brain tumor. A novel diagnostic index based on peak areas for choline and creatine compounds may provide a simple discriminant for differentiating DN from recurrent or residual primary brain tumors.

Environmental, cognitive, and metacognitive influences on text revision: Assessing the evidence

Abstract: To assess progress in understanding text revision, we review research reported since 1980, when process analyses of writing were beginning (Fitzgerald, 1987). A modernized version of the revision model by Flower, Hayes, Carey, Schriver, and Stratman (1986) was used to organize findings about how revision is influenced by environmentally posed rhetorical problems and actual text variables; by cognitive knowledge, strategies, and representations of the text being revised; by metacognitive understanding, monitoring, and control of knowledge and strategies; by interactions among these environmental, cognitive, and metacognitive influences; and by how working memory limits those interactive influences. These influences have been studied with a rich diversity of research approaches, and even though no part of the modernized model has been studied fully, and even though interactions of the model's parts have been examined minimally, clearly interpretable results have been reported about all of the model's parts. Substantial and encouraging progress has been made toward understanding text revision, and the stage has been set for more progress. We suggest investigations to increase understanding of revision and to promote integration of research and theory about reading and writing.

A survey of automatic teller machine usage across the adult life span.

Abstract: The purpose of this study was to analyze automatic teller machine (ATM) usage across the adult life span. We conducted an extensive survey of 9000 people in the Memphis and Atlanta metropolitan areas. Approximately 17% of those people responded. The survey assessed detailed demographic information, experience with technology in general, experience specifically related to ATMs, problems and dislikes with ATMs, and reasons that people do not use ATMs. The survey provided a valuable set of data. First, we have detailed information about the demographics and individual characteristics of ATM users and nonusers; importantly, these data are stratified across the adult life span. In addition, we know the likes and dislikes of ATM users and the types of problems they typically have using ATMs. Moreover, we have a detailed analysis of why adults of all ages may choose not to use ATMs. Training and design implications of these data are discussed.