Showing papers by "University of Memphis published in 2007"

Comorbidity of chronic insomnia with medical problems.

Abstract: Study Objectives: Determine the comorbidity of insomnia with medical problems. Design: Cross-sectional and retrospective. Participants: Community-based population of 772 men and women, aged 20 to 98 years old. Measurements: Self-report measures of sleep, health, depression, and anxiety. Results: People with chronic insomnia reported more of the following than did people without insomnia: heart disease (21.9% vs 9.5%), high blood pressure (43.1% vs 18.7%), neurologic disease (7.3% vs 1.2%), breathing problems (24.8% vs 5.7%), urinary problems (19.7% vs 9.5%), chronic pain (50.4% vs 18.2%), and gastrointestinal problems (33.6% vs 9.2%). Conversely, people with the following medical problems reported more chronic insomnia than did those without those medical problems: heart disease (44.1% vs 22.8%), cancer (41.4% vs 24.6%), high blood pressure (44.0% vs 19.3%), neurologic disease (66.7% vs 24.3%), breathing problems (59.6% vs 21.4%), urinary problems (41.5% vs 23.3%), chronic pain (48.6% vs 17.2%), and gastrointestinal problems (55.4% vs 20.0%). When all medical problems were considered together, only patients with high blood pressure, breathing problems, urinary problems, chronic pain, and gastrointestinal problems continued to have statistically higher levels of insomnia than those without these medical disorders. Conclusion: This study demonstrates significant overlap between insomnia and multiple medical problems. Some research has shown it is possible to treat insomnia that is comorbid with select psychiatric (depression) and medical (eg, pain and cancer) disorders, which in turn increases the quality of life and functioning of these patients. The efficacy of treating insomnia in many of the above comorbid disorders has not been tested, indicating a need for future treatment research.

The effects of perceived organizational support and perceived supervisor support on employee turnover.

Abstract: This study examines mediated effects of perceived supervisor support (PSS) and perceived organizational support (POS) on turnover cognitions, and their interactive effects on turnover behavior in a sample of 225 social services workers. In this study, we address a seeming contradiction in current findings regarding support and attachments to managers versus attachments to the organization itself. The POS literature suggests fully mediated causal paths to turnover from POS and PSS, through affective commitment. Whereas, the commitment, LMX, and turnover literatures suggest alternative causal paths that imply broader effects for POS and PSS on turnover. Contrary to earlier POS literature, findings showed that PSS had independent effects on turnover cognitions not mediated through POS. Model tests also indicated that POS had significant effects on turnover mediated through normative commitment, as well as affective organizational commitment. Moreover, a new significant interactive relationship was discovered such that low PSS strengthened the negative relationship between POS and turnover, while high PSS weakened it. Implications for research and practice are discussed. Copyright © 2007 John Wiley & Sons, Ltd.

Testing and refining the direct and inferential mediation model of reading comprehension

Abstract: A significant proportion of American high school students struggle with reading comprehension Theoretical models of reading comprehension might help researchers understand these difficulties, because they can point to variables that make the largest contributions to comprehension On the basis of an extensive review of the literature, we created a new model of reading comprehension, the direct and inferential mediation (DIME) model The model hypothesizes relationships among background knowledge, inferences, reading comprehension strategies, vocabulary, and word reading and addresses the direct and mediated effects of these 5 predictors on comprehension The authors tested the fit of the model and 3 variations of the model to data from 175 students in 9th grade The DIME model explained 66% of the variance in comprehension Vocabulary and background knowledge made the largest contributions to comprehension, followed by inference, word reading, and strategies Analyses of participants scoring below the 30th percentile on comprehension showed these students to have low scores on all of the measures The authors suggest that vocabulary and background knowledge interventions might be the best way to begin improving the academic reading comprehension of students like those in the sample

The Art of Conversation Is Coordination Common Ground and the Coupling of Eye Movements During Dialogue

Abstract: When two people discuss something they can see in front of them, what is the relationship between their eye movements? We recorded the gaze of pairs of subjects engaged in live, spontaneous dialogue. Cross-recurrence analysis revealed a coupling between the eye movements of the two conversants. In the first study, we found their eye movements were coupled across several seconds. In the second, we found that this coupling increased if they both heard the same background information prior to their conversation. These results provide a direct quantification of joint attention during unscripted conversation and show that it is influenced by knowledge in the common ground.

A Theoretical Review of Winne and Hadwin’s Model of Self-Regulated Learning: New Perspectives and Directions

Abstract: This theoretical review of Winne and Hadwin’s model of self-regulated learning (SRL) seeks to highlight how the model sheds new light on current research as well as suggests interesting new directions for future work. The authors assert that the model’s more complex cognitive architecture, inclusion of monitoring and control within each phase of learning, and separation of task definition and goal setting into separate phases are all important contributions to the SRL literature. New research directions are outlined, including more nuanced interpretations of judgments of learning and the potential to more thoroughly assess the influence of interactions among cognitive and task conditions on all phases of learning.

Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau

Abstract: The steep, high-relief eastern margin of the Tibetan Plateau has undergone rapid Cenozoic cooling and denudation yet shows little evidence for large-magnitude shortening or accommodation generation in the foreland basin. We address this paradox by using a variety of geomorphic observations to place constraints on the kinematics and slip rates of several large faults that parallel the plateau margin. The Beichuan and Pengguan faults are active, dominantly dextral-slip structures that can be traced continuously for up to 200 km along the plateau margin. Both faults offset fluvial fill terraces that yield inheritance-corrected, cosmogenic 10Be exposure ages of <15 kyr, indicating latest Pleistocene activity. The Pengguan fault appears to have been active in the Holocene at two sites along strike. Latest Quaternary apparent throw rates on both faults are variable along strike but are typically <1 mm yr−1. Rates of strike-slip displacement are likely to be several times higher, probably ∼1–10 mm yr−1 but remain poorly constrained. Late Quaternary folding and dextral strike-slip has also occurred along the western margin of the Sichuan Basin, particularly associated with the present-day mountain front. These observations support models for the formation and maintenance of the eastern plateau margin that do not involve major upper crustal shortening. They also suggest that activity on the margin-parallel faults in eastern Tibet may represent a significant seismic hazard to the densely populated Sichuan Basin.

Toward an Affect-Sensitive AutoTutor

Abstract: Here, we consider the possibility of enabling AutoTutor, an intelligent tutoring system, to process learners' affective and cognitive states. AutoTutor is a fully automated computer tutor that simulates human tutors and converses with students in natural language.

Profile effects in early bilingual language and literacy

Abstract: Bilingual children’s language and literacy is stronger in some domains than others. Reanalysis of data from a broad-scale study of monolingual English and bilingual Spanish–English learners in Miami provided a clear demonstration of “profile effects,” where bilingual children perform at varying levels compared to monolinguals across different test types. The profile effects were strong and consistent across conditions of socioeconomic status, language in the home, and school setting (two way or English immersion). The profile effects indicated comparable performance of bilingual and monolingual children in basic reading tasks, but lower vocabulary scores for the bilinguals in both languages. Other test types showed intermediate scores in bilinguals, again with substantial consistency across groups. These profiles are interpreted as primarily due to the “distributed characteristic” of bilingual lexical knowledge, the tendency for bilingual individuals to know some words in one language but not the other and vice versa.

Web-based recruitment: effects of information, organizational brand, and attitudes toward a Web site on applicant attraction.

Abstract: Recruitment theory and research show that objective characteristics, subjective considerations, and critical contact send signals to prospective applicants about the organization and available opportunities. In the generating applicants phase of recruitment, critical contact may consist largely of interactions with recruitment sources (e.g., newspaper ads, job fairs, organization Web sites); however, research has yet to fully address how all 3 types of signaling mechanisms influence early job pursuit decisions in the context of organizational recruitment Web sites. Results based on data from 814 student participants searching actual organization Web sites support and extend signaling and brand equity theories by showing that job information (directly) and organization information (indirectly) are related to intentions to pursue employment when a priori perceptions of image are controlled. A priori organization image is related to pursuit intentions when subsequent information search is controlled, but organization familiarity is not, and attitudes about a recruitment source also influence attraction and partially mediate the effects of organization information. Theoretical and practical implications for recruitment are discussed.

The transcription factor Mrr1p controls expression of the MDR1 efflux pump and mediates multidrug resistance in Candida albicans.

Abstract: Constitutive overexpression of the MDR1 (multidrug resistance) gene, which encodes a multidrug efflux pump of the major facilitator superfamily, is a frequent cause of resistance to fluconazole and other toxic compounds in clinical Candida albicans strains, but the mechanism of MDR1 upregulation has not been resolved. By genome-wide gene expression analysis we have identified a zinc cluster transcription factor, designated as MRR1 (multidrug resistance regulator), that was coordinately upregulated with MDR1 in drug-resistant, clinical C. albicans isolates. Inactivation of MRR1 in two such drug-resistant isolates abolished both MDR1 expression and multidrug resistance. Sequence analysis of the MRR1 alleles of two matched drug-sensitive and drug-resistant C. albicans isolate pairs showed that the resistant isolates had become homozygous for MRR1 alleles that contained single nucleotide substitutions, resulting in a P683S exchange in one isolate and a G997V substitution in the other isolate. Introduction of these mutated alleles into a drug-susceptible C. albicans strain resulted in constitutive MDR1 overexpression and multidrug resistance. By comparing the transcriptional profiles of drug-resistant C. albicans isolates and mrr1Δ mutants derived from them and of C. albicans strains carrying wild-type and mutated MRR1 alleles, we defined the target genes that are controlled by Mrr1p. Many of the Mrr1p target genes encode oxidoreductases, whose upregulation in fluconazole-resistant isolates may help to prevent cell damage resulting from the generation of toxic molecules in the presence of fluconazole and thereby contribute to drug resistance. The identification of MRR1 as the central regulator of the MDR1 efflux pump and the elucidation of the mutations that have occurred in fluconazole-resistant, clinical C. albicans isolates and result in constitutive activity of this trancription factor provide detailed insights into the molecular basis of multidrug resistance in this important human fungal pathogen.

Oxytocin: behavioral associations and potential as a salivary biomarker.

Abstract: Oxytocin (OT) is a neuropeptide that is produced primarily in the hypothalamus and is best known for its role in mammalian birth and lactation. Recent evidence also implicates OT in social behaviors, including parental behavior, the formation of social bonds, and the management of stressful experiences. OT is reactive to stressors, and plays a role in the regulation of both the central and autonomic nervous system, including effects on immune and cardiovascular function. Knowledge of patterns of OT release would be of value in many fields of science and medicine. However, measurements of OT concentration in blood are infrequently performed, and previous attempts to measure OT in saliva have been unsuccessful. Using a sensitive enzyme immunoassay (EIA) and concentrated samples we were able to detect reproducible changes in salivary OT as a function of lactation and massage. These results indicate that measurements of biologically relevant changes in salivary OT are possible. These results confirm the biological relevance of changes in salivary OT with stressors and support saliva as a noninvasive source to monitor central neuroendocrine function.

A Linguistic Analysis of Simplified and Authentic Texts

Abstract: The opinions of second language learning (L2) theorists and researchers are divided over whether to use authentic or simplified reading texts as the means of input for beginning- and intermediate-level L2 learners. Advocates of both approaches cite the use of linguistic features, syntax, and discourse structures as important elements in support of their arguments, but there has been no conclusive study that measures these differences and their implications for L2 learning. The purpose of this article is to provide an exploratory study that fills this gap. Using the computational tool Coh-Metrix, this study investigates the differences between the linguistic structures of sampled simplified texts and those of authentic reading texts in order to provide a better understanding of the linguistic features that comprise these text types. The findings demonstrate that these texts differ significantly, but not always in the manner supposed by the authors of relevant scholarship. This research is meant to enable material developers, publishers, and classroom teachers to judge more accurately the value of both authentic and simplified texts.

Design of space trusses using big bang–big crunch optimization

Abstract: A procedure for designing low-weight space trusses based on the innovative Big Bang–Big Crunch (BB–BC) optimization method is developed for both discrete and continuous variable optimization. BB-BC optimization is a population-based heuristic search consisting of two parts: The Big Bang where candidate solutions are randomly distributed over the search space; and a Big Crunch where a contraction operation estimates a weighted average or center of mass for the population. Each sequential Big Bang is then randomly distributed about the center of mass. The objective of the optimization is to minimize the total weight (or cost) of the structure subjected to material and performance constraints in the form of stress and deflection limits. Designs are evaluated for fitness based on their penalized structural weight, which represents the actual truss weight and the degree to which the design constraints are violated. BB-BC optimization has several advantages over other evolutionary methods: Most significantly, a...

What Attracts Foreign Investors? An Examination of Human Rights and Foreign Direct Investment

Abstract: Though the prospective relationship between foreign direct investment (FDI) and human rights has long been a prominent issue within the global political economy, the linkage is empirically underdeveloped. Rather, the conventional wisdom that FDI and respect for human rights are inherently contradictory has persisted. Instead, we posit that respect for human rights may encourage FDI. To examine this issue, we assess the direct effects of human rights upon FDI as well as the extent to which human rights indirectly affects FDI through its impact upon human capital. Using a system of simultaneous equations, we find respect for human rights to have a positive impact upon FDI.

The Impact of Science Knowledge, Reading Skill, and Reading Strategy Knowledge on More Traditional “High-Stakes” Measures of High School Students’ Science Achievement

Abstract: This study examined how well cognitive abilities predict high school students’ science achievement as measured by traditional content-based tests. Students (n = 1,651) from four high schools in three states were assessed on their science knowledge, reading skill, and reading strategy knowledge. The dependent variable, content-based science achievement, was measured in terms of students’ comprehension of a science passage, science course grade, and state science test scores. The cognitive variables reliably predicted all three measures of science achievement, and there were also significant gender differences. Reading skill helped the learner compensate for deficits in science knowledge for most measures of achievement and had a larger effect on achievement scores for higher knowledge than lower knowledge students. Implications for pedagogy and science assessment are discussed.

vocd: A theoretical and empirical evaluation

Abstract: A reliable index of lexical diversity (LD) has remained stubbornly elusive for over 60 years. Meanwhile, researchers in fields as varied as stylistics, neuropathology, language acquisition, and even forensics continue to use flawed LD indices — often ignorant that their results are questionable and in some cases potentially dangerous. Recently, an LD measurement instrument known as vocd has become the virtual tool of the LD trade. In this paper, we report both theoretical and empirical evidence that calls into question the rationale for vocd and also indicates that its reliability is not optimal. Although our evidence shows that vocd's output (D) is a relatively robust indicator of the aggregate probabilities of word occurrences in a text, we show that these probabilities — and thus also D — are affected by text length. Malvern, Richards, Chipere and Duran (2004) acknowledge that D (as calculated by vocd's default method) can be affected by text length, but claim that the effects are not significant for t...

Influences of top management team incentives on firm risk taking

Abstract: In our work, the influences on subsequent firm risk taking of fixed incentives relative to variable incentives as well as the separate effects on subsequent corporate risk taking of variable incentives are examined. Focusing on the top management team members, we find a higher proportion of incentives that are devoted to fixed incentives relative to variable incentives tend to be inversely associated with subsequent firm risk taking. Managerial stock options are directly and uniformly associated with subsequent corporate risk taking. Executive shareholdings, however, display a curvilinear relationship with subsequent enterprise risk taking. Copyright © 2007 John Wiley & Sons, Ltd.

Perceived critical mass and the adoption of a communication technology

Abstract: Computer-based communication technologies are increasingly important to personal and organizational communication One important factor related to the adoption and diffusion of communication innovations is critical mass Critical mass influences the adoption and diffusion of interactive communication innovations, both through network externalities and through sustainability of the innovation Unfortunately, critical mass is difficult to measure and is typically only demonstrable after the critical mass point has been reached Potential adopters’ perceptions of critical mass also may be important to adoption decisions In this paper, we extend this thinking using a synthesis of the Theory of Reasoned Action and Diffusion of Innovation theory by developing a research model The model is empirically tested using survey data that are analyzed using partial least squares The focal innovation is instant messaging Results indicate that perceived critical mass influences use intentions directly and through perceptions of the characteristics of the innovation The perceived innovation characteristics impact attitude toward use, which in turn impacts use intentions The model predicts a sizable and significant portion of both attitudes and use intentions Further, perceived critical mass is able to explain a significant portion of the variance in each perceived innovation characteristic Implications for research and practice are discussed

The solution of nonlinear inverse problems and the Levenberg-Marquardt method

Abstract: Although the Levenberg-Marquardt damped least-squares method is an extremely powerful tool for the iterative solution of nonlinear problems, its theoretical basis has not been described adequately in the literature. This is unfortunate, because Levenberg and Marquardt approached the solution of nonlinear problems in different ways and presented results that go far beyond the simple equation that characterizes the method. The idea of damping the solution was introduced by Levenberg, who also showed that it is possible to do that while at the same time reducing the value of a function that must be minimized iteratively. This result is not obvious, although it is taken for granted. Moreover, Levenberg derived a solution more general than the one currently used. Marquardt started with the current equation and showed that it interpolates between the ordinary least-squares-method and the steepest-descent method. In this tutorial, the two papers are combined into a unified presentation, which will help the reader gain a better understanding of what happens when solving nonlinear problems. Because the damped least-squares and steepest-descent methods are intimately related, the latter is also discussed, in particular in its relation to the gradient. When the inversion parameters have the same dimensions (and units), the direction of steepest descent is equal to the direction of minus the gradient. In other cases, it is necessary to introduce a metric (i.e., a definition of distance) in the parameter space to establish a relation between the two directions. Although neither Levenberg nor Marquardt discussed these matters, their results imply the introduction of a metric. Some of the concepts presented here are illustrated with the inversion of synthetic gravity data corresponding to a buried sphere of unknown radius and depth. Finally, the work done by early researchers that rediscovered the damped least-squares method is put into a historical context.

Revisiting Negative Selection Algorithms

Abstract: This paper reviews the progress of negative selection algorithms, an anomaly/change detection approach in Artificial Immune Systems (AIS). Following its initial model, we try to identify the fundamental characteristics of this family of algorithms and summarize their diversities. There exist various elements in this method, including data representation, coverage estimate, affinity measure, and matching rules, which are discussed for different variations. The various negative selection algorithms are categorized by different criteria as well. The relationship and possible combinations with other AIS or other machine learning methods are discussed. Prospective development and applicability of negative selection algorithms and their influence on related areas are then speculated based on the discussion.

The empirical relationship between ownership characteristics and audit fees

Abstract: The present study examines the empirical relationship between ownership characteristics and audit fees. The basic premise is that the level of ownership sophistication and the extent to which ownership is large and substantial impact the effectiveness of stockholder monitoring on corporate affairs including the financial reporting process. Furthermore, high managerial ownership firms may experience a decline in agency problems in financial reporting due to a decrease in managerial propensity to misreport financial results. By employing a cross-sectional least squares regression analysis for a sample of 358 New York Stock Exchange-listed firms audited by the Big Five auditors, we find evidence of a significantly positive relationship between diffused institutional stock ownership (i.e., having less than 5% individual shareholding) and audit fees, and a significantly negative relationship between institutional blockholder ownership (i.e., having 5% or more individual shareholding) and audit fees. Finally, we document that managerial stock ownership is negatively associated with audit fees. We do not, however, find evidence of any relationship between noninstitutional blockholder ownership (with at least 5% individual stock ownership) and audit fees. The study's main results hold in various specification tests including when the effects of board-related and audit committee variables are factored in the analysis. Based on the observed relationship between the ownership variables and audit fees, we suggest that the ownership characteristics of a firm as a part of its governance mechanism constitute an important determinant of audit fees.

The Effects of Perceived Management Concern for Frontline Employees and Customers on Turnover Intentions: Moderating Role of Employment Status

Abstract: This study develops and tests a turnover intentions model, which examines the effects of frontline employees' perceptions of management concern for employees and customers on turnover intentions, m...

The effectiveness of bereavement interventions with children: a meta-analytic review of controlled outcome research.

Abstract: Grief therapies with children are becoming increasingly popular in the mental health community. Nonetheless, questions persist about how well these treatments actually help with children's adjustment to the death of a loved one. This study used meta-analytic techniques to evaluate the general effectiveness of bereavement interventions with children. A thorough quantitative review of the existing controlled outcome literature (n = 13) yielded a conclusion akin to earlier reviews of grief therapy with adults, namely that the child grief interventions do not appear to generate the positive outcomes of other professional psychotherapeutic interventions. However, studies that intervened in a time-sensitive manner and those that implemented specific selection criteria produced better outcomes than investigations that did not attend to these factors.

Expanding the Obesity Research Paradigm to Reach African American Communities

Abstract: Obesity is more prevalent among African Americans and other racial and ethnic minority populations than among whites. The behaviors that determine weight status are embedded in the core social and cultural processes and environments of day-to-day life in these populations. Therefore, identifying effective, sustainable solutions to obesity requires an ecological model that is inclusive of relevant contextual variables. Race and ethnicity are potent stratification variables in U.S. society and strongly influence life contexts, including many aspects that relate to eating and physical activity behaviors. This article describes a synthesis initiated by the African American Collaborative Obesity Research Network (AACORN) to build and broaden the obesity research paradigm. The focus is on African Americans, but the expanded paradigm has broader implications and may apply to other populations of color. The synthesis involves both community and researcher perspectives, drawing on and integrating insights from an expanded set of knowledge domains to promote a deeper understanding of relevant contexts. To augment the traditional, biomedical focus on energy balance, the expanded paradigm includes insights from family sociology, literature, philosophy, transcultural psychology, marketing, economics, and studies of the built environment. We also emphasize the need for more attention to tensions that may affect African American or other researchers who identify or are identified as members of the communities they study. This expanded paradigm, for which development is ongoing, poses new challenges for researchers who focus on obesity and obesity-related health disparities but also promises discovery of new directions that can lead to new solutions.