Showing papers by "University of Memphis published in 2001"

The childhood trauma questionnaire in a community sample: psychometric properties and normative data.

Abstract: Interpretation of research on the prevalence and sequelae of childhood trauma has been hindered by the use of assessment instruments with unknown psychometric properties. Thus, we examined the psychometric properties of a new childhood trauma measure, the Childhood Trauma Questionnaire (CTQ). The CTQ has demonstrated strong psychometric properties in clinical samples; limited information exists on its psychometric properties in community samples. Therefore, we explored the factor structure and reliability of the CTQ in a community sample and calculated normative data. Consistent with previous literature, a 5-factor model best described the CTQ, with a hierarchical model also providing excellent fit. Additionally, the CTQ demonstrated acceptable internal consistency. Overall, our findings suggest that the CTQ is appropriate for use in a community sample.

A meta-analysis of the effects of cigarette smoking on bone mineral density.

Abstract: To determine the magnitude and mediators of the association between cigarette smoking and bone mass in the epidemiologic literature we reviewed articles, published abstracts and conference proceedings, identified through MEDLINE, psychological abstracts, conference proceedings, and article bibliographies. We studied cross-sectional and prospective human studies that provided a quantitative measure of bone mass (X-ray, absorptiometry, or computed tomography) as a function of cigarette smoking exposure. Effects were expressed as pooled standardized mean differences for categorical comparisons (e.g. bone mass in current versus nonsmokers), and as pooled correlation coefficients for continuous comparisons (e.g., correlation of bone mass and pack-years of smoking). Effects were derived for combined bone sites (all bone sites pooled within each study) and four specific sites (hip, lumbar spine, forearm, and os calcis), and were examined overall and as a function of subject and methodologic characteristics (gender, age, body weight, menopausal status, health status). Data were pooled across 86 studies, enrolling 40, 753 subjects. Smokers had significantly reduced bone mass compared with nonsmokers (never and former smokers) at all bone sites, averaging a one-tenth standard deviation (SD) deficit for combined sites. Deficits were especially pronounced at the hip, where the bone mass of current smokers was one-third of a SD less than that of never smokers. Overall, effects were greatest in men and in the elderly, and were dosedependent. In prospective studies, smokers had greater rates of bone loss over time compared with nonsmokers. Bone mass differences remained significant after controlling for age and body weight differences between the two groups. Absolute effect sizes at most bone sites were greatest for current smokers compared with never smokers, intermediate for current smokers compared with former smokers, and lowest for former smokers compared with never smokers, suggesting that smoking cessation may have a positive influence on bone mass. Based on these data, it is estimated that smoking increases the lifetime risk of developing a vertebral fracture by 13% in women and 32% in men. At the hip, smoking is estimated to increase lifetime fracture risk by 31% in women and 40% in men. It appears that smoking has an independent, dose-dependent effect on bone loss, which increases fracture risk, and may be partially reversed by smoking cessation. Given the public health implications of smoking on bone health, it is important that this information be incorporated into smoking prevention and cessation efforts

Algorithms for facility location problems with outliers

Abstract: Facility location problems are traditionally investigated with the assumption that all the clients are to be provided service. A significant shortcoming of this formulation is that a few very distant clients, called outliers, can exert a disproportionately strong influence over the final solution. In this paper we explore a generalization of various facility location problems (K-center, K-median, uncapacitated facility location etc) to the case when only a specified fraction of the customers are to be served. What makes the problems harder is that we have to also select the subset that should get service. We provide generalizations of various approximation algorithms to deal with this added constraint.

ERP implementation issues in advanced and developing countries

Abstract: There is an increasing need to implement a total business solution which supports major functionalities of a business. Enterprise resource planning (ERP) software is designed to meet this need, and has been widely adopted by organizations in developed countries. Meanwhile, ERP is beginning to appear in many organizations of developing countries. Little research has been conducted to compare the implementation practices of ERP in developed vs developing countries. Our research shows that ERP technology faces additional challenges in developing countries related to economic, cultural, and basic infrastructure issues. This article identifies a range of issues concerning ERP implementation by making a comparison of advanced and developing countries.

Low-complexity fuzzy relational clustering algorithms for Web mining

Abstract: This paper presents new algorithms-fuzzy c-medoids (FCMdd) and robust fuzzy c-medoids (RFCMdd)-for fuzzy clustering of relational data. The objective functions are based on selecting c representative objects (medoids) from the data set in such a way that the total fuzzy dissimilarity within each cluster is minimized. A comparison of FCMdd with the well-known relational fuzzy c-means algorithm (RFCM) shows that FCMdd is more efficient. We present several applications of these algorithms to Web mining, including Web document clustering, snippet clustering, and Web access log analysis.

Intelligent tutoring systems with conversational dialogue

Abstract: Many of the intelligent tutoring systems that have been developed during the last 20 years have proven to be quite successful, particularly in the domains of mathematics, science, and technology. They produce significant learning gains beyond classroom environments. They are capable of engaging most students' attention and interest for hours. We have been working on a new generation of intelligent tutoring systems that hold mixed-initiative conversational dialogues with the learner. The tutoring systems present challenging problems and questions to the learner, the learner types in answers in English, and there is a lengthy multiturn dialogue as complete solutions or answers evolve. This article presents the tutoring systems that we have been developing. AutoTutor is a conversational agent, with a talking head, that helps college students learn about computer literacy. andes, atlas, and why2 help adults learn about physics. Instead of being mere information-delivery systems, our systems help students actively construct knowledge through conversations.

Cardiorespiratory events recorded on home monitors: Comparison of healthy infants with those at increased risk for SIDS.

Abstract: ContextHome monitors designed to identify cardiorespiratory events are frequently used in infants at increased risk for sudden infant death syndrome (SIDS), but the efficacy of such devices for this use is unproven.ObjectiveTo test the hypothesis that preterm infants, siblings of infants who died of SIDS, and infants who have experienced an idiopathic, apparent life-threatening event have a greater risk of cardiorespiratory events than healthy term infants.DesignLongitudinal cohort study conducted from May 1994 through February 1998.SettingFive metropolitan medical centers in the United States.ParticipantsA total of 1079 infants (classified as healthy term infants and 6 groups of those at risk for SIDS) who, during the first 6 months after birth, were observed with home cardiorespiratory monitors using respiratory inductance plethysmography to detect apnea and obstructed breathing.Main Outcome MeasuresOccurrence of cardiorespiratory events that exceeded predefined conventional and extreme thresholds as recorded by the monitors.ResultsDuring 718 358 hours of home monitoring, 6993 events exceeding conventional alarm thresholds occurred in 445 infants (41%). Of these, 653 were extreme events in 116 infants (10%), and of those events with apnea, 70% included at least 3 obstructed breaths. The frequency of at least 1 extreme event was similar in term infants in all groups, but preterm infants were at increased risk of extreme events until 43 weeks' postconceptional age.ConclusionsIn this study, conventional events are quite common, even in healthy term infants. Extreme events were common only in preterm infants, and their timing suggests that they are not likely to be immediate precursors to SIDS. The high frequency of obstructed breathing in study participants would likely preclude detection of many events by conventional techniques. These data should be important for designing future monitors and determining if an infant is likely to be at risk for a cardiorespiratory event.

Earthquake triggering by seismic waves following the Landers and Hector Mine earthquakes

Abstract: The proximity and similarity of the 1992, magnitude 7.3 Landers and 1999, magnitude 7.1 Hector Mine earthquakes in California permit testing of earthquake triggering hypotheses not previously possible. The Hector Mine earthquake confirmed inferences that transient, oscillatory ‘dynamic’ deformations radiated as seismic waves can trigger seismicity rate increases, as proposed for the Landers earthquake1,2,3,4,5,6. Here we quantify the spatial and temporal patterns of the seismicity rate changes7. The seismicity rate increase was to the north for the Landers earthquake and primarily to the south for the Hector Mine earthquake. We suggest that rupture directivity results in elevated dynamic deformations north and south of the Landers and Hector Mine faults, respectively, as evident in the asymmetry of the recorded seismic velocity fields. Both dynamic and static stress changes seem important for triggering in the near field with dynamic stress changes dominating at greater distances. Peak seismic velocities recorded for each earthquake suggest the existence of, and place bounds on, dynamic triggering thresholds. These thresholds vary from a few tenths to a few MPa in most places, depend on local conditions, and exceed inferred static thresholds by more than an order of magnitude. At some sites, the onset of triggering was delayed until after the dynamic deformations subsided. Physical mechanisms consistent with all these observations may be similar to those that give rise to liquefaction or cyclic fatigue.

A blow-up result for a nonlinear wave equation with damping: The critical case

Abstract: Using a different and much shorter approach, we prove a blow-up result which is more general than the interesting blow-up result of G Todorova and B Yordanov concerning a nonlinear wave equation with a damping term We also show that the critical exponent belongs to the blow-up case This problem had been left open by these authors

Brand equity: is it more important in services?

Abstract: While the brand equity associated with tangible goods has received a great deal of attention in the literature, a basic understanding of the nature of brand equity for services has yet to emerge. Most of what is known about brand equity for services is based on theoretical or anecdotal evidence. In addition, the presumed differences in brand equity associated with search‐dominant, experience‐dominant, and credence‐dominant services has yet to be empirically examined. The objectives of this study are threefold: to empirically test whether brand equity is more important for services than for tangible goods, to test whether the presumed differences in brand equity for search‐, experience‐, and credence‐dominant services can be confirmed in an empirical examination, and to assess whether consumer knowledge of a product category has an effect on the importance of brand equity across product types. Contrary to suppositions in the literature, the results indicate that brand equity is more important for tangible ...

Supporting program comprehension using semantic and structural information

Abstract: Focuses on investigating the combined use of semantic and structural information of programs to support the comprehension tasks involved in the maintenance and reengineering of software systems. "Semantic information" refers to the domain-specific issues (both the problem and the development domains) of a software system. The other dimension, structural information, refers to issues such as the actual syntactic structure of the program, along with the control and data flow that it represents. An advanced information retrieval method, latent semantic indexing, is used to define a semantic similarity measure between software components. Components within a software system are then clustered together using this similarity measure. Simple structural information (i.e. the file organization) of the software system is then used to assess the semantic cohesion of the clusters and files with respect to each other. The measures are formally defined for general application. A set of experiments is presented which demonstrates how these measures can assist in the understanding of a nontrivial software system, namely a version of NCSA Mosaic.

Teaching Tactics and Dialog in AutoTutor

Abstract: The Tutoring Research Group at the University of Memphis has developed a computer tutor (called AutoTutor) that simulates the discourse patterns and pedagogical strategies of a typical human tutor. The dialog tactics were based on a previous project that dissected 100 hours of naturalistic tutoring sessions. AutoTutor is currently targeted for college students in introductory computer literacy courses, who learn the fundamentals of hardware, operating systems, and the Internet. Instead of merely being an information delivery system, AutoTutor serves as a discourse prosthesis (or collaborative scaffold) that assists the student in actively constructing knowledge. A dialog manager coordinates the conversation that occurs between a learner and a pedagogical agent, whereas lesson content and world knowledge are represented in a curriculum script and latent semantic analysis. The agent is a talking head with discourse- sensitive facial expressions and synthesized speech. Evaluations of AutoTutor have shown that the tutoring system improves learning and memory of the lessons by .5 to .6 standard deviation units. This article describes the components of AutoTutor and contrasts two versions that follow somewhat different teaching tactics.

The scaling window of the 2-SAT transition

Abstract: We consider the random 2-satisfiability (2-SAT) problem, in which each instance is a formula that is the conjunction of m clauses of the form x∨y, chosen uniformly at random from among all 2-clauses on n Boolean variables and their negations. As m and n tend to infinity in the ratio m/nα, the problem is known to have a phase transition at αc=1, below which the probability that the formula is satisfiable tends to one and above which it tends to zero. We determine the finite-size scaling about this transition, namely the scaling of the maximal window W(n, δ)=(α−(n,δ), α+(n,δ)) such that the probability of satisfiability is greater than 1−δ for α α+. We show that W(n,δ)=(1−Θ(n−1/3), 1+Θ(n−1/3)), where the constants implicit in Θ depend on δ. We also determine the rates at which the probability of satisfiability approaches one and zero at the boundaries of the window. Namely, for m=(1+e)n, where e may depend on n as long as |e| is sufficiently small and |e|n1/3 is sufficiently large, we show that the probability of satisfiability decays like exp(−Θ(ne3)) above the window, and goes to one like 1−Θ(n−1|e|−3 below the window. We prove these results by defining an order parameter for the transition and establishing its scaling behavior in n both inside and outside the window. Using this order parameter, we prove that the 2-SAT phase transition is continuous with an order parameter critical exponent of 1. We also determine the values of two other critical exponents, showing that the exponents of 2-SAT are identical to those of the random graph. © 2001 John Wiley & Sons, Inc. Random Struct. Alg., 18: 201–256 2001

Age and Sex Differences in the Cerebellum and the Ventral Pons: A Prospective MR Study of Healthy Adults

Abstract: BACKGROUND AND PURPOSE: The human brain exhibits a complex pattern of differential aging. The purpose of this study was to examine whether age differences in the volume of cerebellar regions and the ventral pons are differential or generalized, whether the age-related shrinkage is linear or exponential, and whether there are sex differences in the size of the cerebellum and pons. METHODS: The volumes of the cerebellar hemispheres (excluding the vermis and the peduncles), the vermis, and the ventral pons were estimated from the prospectively acquired MR scans of 190 healthy volunteers (aged 18–81 years). The relation between regional volumes, age, and sex was assessed while taking into account differences in body size (height). RESULTS: We found a moderate age-related reduction in the volume of the cerebellar hemispheres and the cerebellar vermis. In contrast to previous findings that suggested differential vulnerability of the posterior vermis, the age-related shrinkage of the vermian lobules was uniform—about 2% per decade. In accord with all reports in the literature, the size of the ventral pons was unrelated to age. The volume of the cerebellar hemispheres, the vermis, and the ventral pons were larger in men, even after adjustment for height. The magnitude of the sex difference was the largest in the hemispheres and the anterior vermis, and the smallest in the lobules VI–VII (declive-folium-tuber). CONCLUSION: Moderate age-related shrinkage of the cerebellum and lack of age-related differences in the ventral pons are robust phenomena. However, in all likelihood, the effects of age on the cerebellum are not differential but uniform. The cerebellum and the pons are larger in men than in women and the difference is especially pronounced in the cerebellar hemispheres and the anterior vermis.

The Utility of the Ces-D as a Depression Screening Measure among Low-Income Women Attending Primary Care Clinics

Abstract: Objective:Depressive disorders are among the most common medical disorders seen in primary care practice. The Center for Epidemiologic Studies-Depression (CES-D) scale is one of the measures commonly suggested for detecting depression in these clinics. However, to our knowledge, there have been no previous studies examining the validity of the CES-D among low-income women attending primary care clinics.Method:Low-income women attending public primary care clinics (n = 179, ages 20–77) completed the CES-D and the Diagnostic Interview Schedule for the DSM-IV (DIS-IV).Results:The results supported the validity of the CES-D. The standard cut-score of 16 and above yielded a sensitivity of .95 and specificity of .70 in predicting Major Depressive Disorder (MDD). However, over two-thirds of those who screened positive did not meet criteria for MDD (positive predictive value = .28). The standard cut-score appears valid, but inefficient for depression screening in this population. An elevated cut-score of 34 yield...

The Phenomenon of Substantive Conflict in the Family Firm: A Cross‐Generational Study

Abstract: This study investigates the influence that family members exert on the extent and frequency of substantive conflict within family firms across generations as a result of their familial relationship...

Children's attitudes and behavioral intentions toward a peer with autistic behaviors: does a brief educational intervention have an effect?

Abstract: This study examined children's ratings of attitudes and behavioral intentions toward a peer presented with or without autistic behaviors. The impact of information about autism on these ratings was investigated as well as age and gender effects. Third- and sixth-grade children (N = 233) were randomly assigned to view a video of the same boy in one of three conditions: No Autism, Autism, or Autism/Information. Children at both grade levels showed less positive attitudes toward the child in the two autism conditions. In rating their own behavioral intentions, children showed no differences between conditions. However, in attributing intentions to their classmates, older children and girls gave lower ratings to the child in the autism conditions. Information about autism did not affect ratings of either attitudes or behavioral intentions as ascribed to self or others.

Extending the Construct of Consumer Ethnocentrism: When Foreign Products Are Preferred

Abstract: Purpose – This research has the purpose of exploring whether the construct of consumer ethnocentrism extends to contexts in which foreign products are preferred to domestic products.Design/methodology/approach – The study evaluates the psychometric properties of the consumer ethnocentrism scale (CETSCALE) in the transition economies of China and Russia using both student and non‐student samples. A valid and reliable six‐item version of the CETSCALE is developed based on these samples. The refined six‐item scale is then validated through a re‐analysis of Netemeyer et al.'s data collected in four developed countries.Findings – Findings show that the scale can be used effectively in these transitional economies. A consistent pattern of support is found for the six‐item CETSCALE across eight samples from six countries.Originality/value – The research provides practicing marketers as well as international researchers with a parsimonious six‐item CETSCALE that can be used in both developed and transition economies.

The Impact of Midpoint Responses and Reverse Coding on Survey Data

Abstract: Counselors conducting survey research have many item format options to contemplate This study examined midpoint selection and the effect on reliability of (a) including or excluding midpoint optio

An index structure for efficient reverse nearest neighbor queries

Abstract: The Reverse Nearest Neighbor (RNN) problem is to find all points in a given data set whose nearest neighbor is a given query point. Just like the Nearest Neighbor (NN) queries, the RNN queries appear in many practical situations such as marketing and resource management. Thus, efficient methods for the RNN queries in databases are required. The paper introduces a new index structure, the Rdnn-tree, that answers both RNN and NN queries efficiently. A single index structure is employed for a dynamic database, in contrast to the use of multiple indexes in previous work. This leads to significant savings in dynamically maintaining the index structure. The Rdnn-tree outperforms existing methods in various aspects. Experiments on both synthetic and real world data show that our index structure outperforms previous methods by a significant margin (more than 90% in terms of number of leaf nodes accessed) in RNN queries. It also shows improvement in NN queries over standard techniques. Furthermore, performance in insertion and deletion is significantly enhanced by the ability to combine multiple queries (NN and RNN) in one traversal of the tree. These facts make our index structure extremely preferable in both static and dynamic cases.

TQM as a management strategy for the next millennia

Abstract: Total quality management (TQM) has been acclaimed as an organizational philosophy to enhance global competitiveness. Will TQM continue to be a management philosophy of the future in same shape, size, and design? This paper, through literature search and using field experts, identifies the future role of TQM in businesses facing global markets.

A reexamination of agency theory assumptions: extensions and extrapolations

Abstract: In this paper, we discuss agency theory in the context of the individual principal and agent, and also in the context of the organization and its groups. Agency theory is examined in the context of goal orientation, obligation and reciprocity, risk, and self-interest. We offer propositions given agency theory’s assumptions. We also extend agency theory and offer alternative propositions based on a relaxing of agency theory’s assumptions. In relaxing the assumptions of agency theory, insights from outside the agency literature, specifically from behavioral theories are used. Implications of agency theory and the extension of this theory are also discussed in relation to outcomes associated with economic exchanges.