Showing papers by "University of North Texas published in 1995"

Multiple Regression Approach to Analyzing Contingency Tables: Post Hoc and Planned Comparison Procedures.

Abstract: Post hoc and planned comparison procedures for interpreting chi-square contingency-table test results, not currently discussed in most standard textbooks, are presented. A planned comparison procedure that simplifies the tedious process of partitioning a contingency table by creating single-degree-of-freedom contrasts through a regression-based approach is proposed. Importantly, these post hoc methods supplement the analysis of standardized residuals by reporting the percentage contribution for each cell to the overall chi-square statistic (relative contribution) and to the percentage of variance shared by the two factors (absolute contribution). Both methods can be readily incorporated into existing statistical packages such as SAS or SPSS. The equivalence of the percentage contribution method to the more common standardized residual method is also presented along with an example of a typical application.

Synthesis and application of modulated polymer gels.

Abstract: A class of environmentally responsive materials based on the spatial modulation of the chemical nature of gels is proposed and demonstrated here. The modulation was achieved by limiting the interpenetration of part of one gel network with another gel network. The gels so produced have an internally heterogeneous or modulated structure. Three simple applications based on the modulated gels are described here: a bigel strip, a shape memory gel, and a gel "hand." The bigel strip bends almost to a circle in response to a temperature increase or an increase in solvent concentration. The shape memory gel changes its shape from a straight line to a pentagon to a quadrangle as the temperature increases. These transitions from one shape to another are reversible. The gel "hand" in water can grasp or release an object simply by an adjustment of the temperature.

Alternatives for Ground Water Cleanup

Abstract: Aquifer remediation is one of our most difficult environmental challenges; technological limitations and problems arising from the physical and chemical complexities of contaminated subsurface environments thwart our best efforts. A 19-member committee of leaders in environmental engineering, hydrogeology, epidemiology, environmental economics, and environmental policy has written an ambitious book that broadly addresses the groundwater remediation problem. Topics include site characterization, capabilities and limitations of pump-and-treat and alternative technologies, alternative goals for ground water cleanup, and policy implications. One of the book's strengths is its information base, which includes various public and private groups, data from 80 pump-and-treat sites, and an extensive literature review. The text is clearly written and well organized. Specific conclusions are stated at the end of each major chapter, and sound policy recommendations are offered at the end of the final chapter. An appendix summarizes pump-andtreat systems reviewed during the study. Several case studies, diagrams, and photographs effectively illustrate concepts and ideas conveyed in the text.

The influence of CO2 concentration on stomatal density

Abstract: summary A survey of 100 species and 122 observations has shown an average reduction in stomatal density of 14.3% (SE ±2.2 %) with CO2 enrichment, with 74% of the cases exhibiting a reduction in stomatal density. A sign test demonstrated that stomatal density decreases, in response to CO2, significantly more often than expected by chance. Repeated observations on the same species indicated a significant repeatability in the direction of the stomatal response. Analyses which removed the potential effect of taxonomy on this data set showed no significant patterns in the dependency of the degree of stomatal change on growth form (woodiness vs. non-woodiness; trees vs. shrubs), habitat (cool vs. warm) or stomatal distribution on the leaf (amphi- vs. hypostomatous). Forty-three of the observations had been made in controlled environments and under a typical range in CO., enrichment of 350–700 μmol mol−1. For these cases the average stomatal density declined by 9% (SE ± 3.3%) and 60% of the cases showed reductions in stomatal density. When analyses were restricted to these 43 observations, amphistomatous samples more frequently had greater changes in stomatal density than did hypostomatous samples. The degree of reduction in stomatal density with increasing CO2 increases with initial stomatal density, after the influence of taxonomy is removed using analyses of independent contrasts. When the data were examined for patterns that might be due explicitly to the effects of relatedness, the subclasses of the Hamamelidae and the Rosidae showed highly significant reductions in stomatal density with CO2 (87% of the species studied in the Hamamelidae and 80% of the species in the Rosidae showed reduction with CO2 enrichment) and correlations between initial stomatal density and degree of reduction in stomatal density. The species sampled in the Hamamelidae were dominantly trees, whereas herbs dominated the species in the Rosidae. There were insufficient species studied at lower taxonomic levels to warrant further statistical analyses. This problem results from experimental and observational data being most often restricted to one species per taxonomic level, typically up to the level of order, a feature which can severely limit the extraction of taxonomically-related and ecologically-related plant responses.

With Malice toward Some: How People Make Civil Liberties Judgments

Abstract: Preface: Political tolerance and democratic life Part I. Theoretical Background and Overview: 1. Political tolerance and democratic practice 2. Antecedent considerations and contemporary information 3. Thinking and mood Part II. Contemporary Information and Political Tolerance Judgments: 4. Tolerance judgments and contemporary information - the basic studies Appendix 4A. The basic experiments - manipulation checks Part III. Refining the Model - The Role of Antecedent Conserations as Individual Differences: 5. Threat and political tolerance 6. Democratic values as standing decisions and contemporary information 7. Source credibility, political knowledge and animus in making tolerance judgments - the Texas experiment 8. Individual differences: The influence of personality Part IV. Implications and Conclusions: 9. Intensity, motivations, and behavioral intentions 10. Human nature and political tolerance Appendices Bibliography.

An examination of beliefs about older workers: Do stereotypes still exist?

Abstract: This study examined individuals' beliefs about older workers. Of particular interest was the relationship between those beliefs and individuals' (a) interactions with older workers, (b) supervisory status, and (c) demographic variables. Findings indicated that although older workers hold more positive beliefs about older workers than younger workers hold, even younger workers tended to have generally positive beliefs. Chronological age was found to moderate two relationships. First, the number of younger workers' interactions with older workers significantly, positively affected younger workers' beliefs about older workers. Second, an examination of the interaction between supervisory status and age found that older supervisors hold more negative beliefs about older workers than younger supervisors.

Effective emergency management: reconsidering the bureaucratic approach.

Abstract: The command and control approach is compared with the Emergent Human Resources Model (EHRM) approach to emergency management. Four decades of systematic research shows that a rigid, bureaucratic command and control approach to emergency management generally leads to an ineffective emergency response. Previous studies and our own research suggest that flexible, malleable, loosely coupled, organizational configurations can create a more effective disaster response.

Distress and symptoms of posttraumatic stress disorder in abused women

Abstract: Emotional distress and symptoms of posttraumatic stress disorder (PTSD) were examined among women in psychologically abusive relationships. Women (N = 93) were divided into three groups (none, moderate, severe) according to scores on the violence subscale of the Severity of Violence Against Women Scales (Marshall, 1992). All groups reported serious emotional distress on the Symptom Checklist 90-Revised (Derogatis, 1983) dimensions (e.g. more so than 93% of the nonclinical norm for global distress). Psychoticism was the highest subscale for all groups. Most women (56%) suffered PTSD according to a subscale of the SCL90 (Saunders, Arata, & Kilpatrick, 1990). Difficulties with perception, memory, and motor functions (cognitive failure) more consistently predicted intrusive thoughts. PTSD scores, and attempted suicide than did women's attention to their inner thoughts and feelings (private self-consciousness), which was important for the sample and the subgroup that had sustained severe violence. Limitations and contributions are discussed as are different uses for conservative and inclusive measures of PTSD.

Analysis of Establishing Operations for Self-Injury Maintained by Escape.

Abstract: Self-injurious behavior (SIB) can be maintained through negative reinforcement when, in the context of training or task requirements, it produces escape as a consequence. Several studies have demonstrated methods for identifying and treating SIB maintained by negative reinforcement; however, few analyses of the establishing operations associated with demand situations have been conducted. The current series of studies illustrates a method for identifying some establishing operations for escape by systematically altering certain dimensions of the demand context while maintaining an escape contingency for SIB. Dimensions assessed in these studies included task novelty, duration of instructional sessions, and rate of task presentation. Data indicate that these variables can have establishing properties for behavior maintained by escape. Implications of the results are discussed, as are potential refinements and extensions of the assessment procedures.

Uncertainty and foreign direct investment: the role of moderators

Abstract: The strength of the relationship between uncertainty and the firm′s decision to engage in foreign direct investment (FDI) is moderated by factors such as capital intensity and firm size. Recognizes two types of uncertainty, internal and external. Develops specific hypotheses about how the influence of external uncertainty on FDI is conditioned by certain moderators. Not enough is known about how internal uncertainty affects the FDI to develop specific predictions about moderators. However, these effects are empirically determined. Uses data on US international service firms to test the various effects using logistic regression. Results suggest that the moderators affect both the strength and the direction of the impact that internal and external uncertainty have on foreign direct investment.

Attachment Theory, Counseling Process, and Supervision

Abstract: This article is designed to stimulate interest in the clinical utility of attachment theory and examine how its constructs are relevant to counseling and counseling supervision. The initial section illustrates attachment constructs in action and demonstrates how the theory and its related research can be used to conceptualize clients' experience in their emotionally important relationships. The authors then discuss counseling process focusing on the ways attachment theory can contribute to understanding the client-counselor relationship and change strategies. The implications of the central constructs are also explored in relation to counseling supervision. In concluding, the authors discuss research and clinical extensions of attachment theory, alluding briefly to areas that are also extensions of traditional counseling psychology. Throughout, the article's intent is to help the reader appreciate the complexity of attachment theory as well as its science-practice links and its potential contribution to c...

Clenbuterol: A substitute for anabolic steroids?

Abstract: Clenbuterol is a recently popular drug used by athletes in many sports for its purported anabolic effects and reduction of subcutaneous fat. It is a beta-2 (beta 2) agonist prescribed overseas as a bronchodilator, but not approved for use in this country. It is on the banned substance list of the United States Olympic Committee. To avoid any erosion of confidence, physicians caring for athletes need accurate information regarding clenbuterol. Such information is unavailable within the routine medical environs. A review of the literature of animal husbandry reveals that this drug, when administered in doses far greater than those required for bronchodilation, does indeed increase the deposition rate of lean mass and retard adipose gain. There are no human studies available. Animal studies were conducted on laboratory and slaughter stock. No investigation into long-term cardiovascular side effects has been undertaken. The rate of extrapolation from animal studies to unsupervised human usage is alarming. If this category of drugs does preserve lean mass in humans, there are legitimate medical applications. Trials of efficacy and safety are needed.

US Military Aid in the 1980s: A Global Analysis

Abstract: Although researchers have recently made some progress in explaining the outputs of the US economic aid decision-making process, their efforts to explain the allocation of US military aid have been rather disappointing. In this article, we follow previous studies that have assumed a two-stage process leading up to the allocation of military aid, while making three significant improvements over those efforts. First we employ a better model, including a variety of political, strategic, economic, and humanitarian variables we hypothesize to be related to the allocation of military aid. Second, we solve the 'low n' difficulty that plagued previous research, by employing an extensive dataset that covers a global sample of countries covering the 1983-8 period. And third, unlike previous research where a two-stage process has been assumed, we employ a methodology that solves the difficulties associated with selection bias, which arises when two interrelated decisions are modeled separately. As a result of these improvements our results are much stronger than those of previous studies. We find that strategic, political, and economic interests, as well as human rights concerns and economic development, have been considered in the US military aid decision-making process.

International Realism and the Science of Politics: Thucydides, Machiavelli, and Neorealism

Abstract: Contemporary structural realism, or “neorealism,” has become immensely influential in the contemporary study of international relations, due in part to its claims to be more scientific than its predecessors. The realist tradition, however, has always laid claim to a species of scientific rigor. The arguments of the classical realists Thucydides and Machiavelli are used to assess the claims of contemporary realism to be an advance over classical realism, and to investigate the relation between the science of politics and the ethical issues raised by realism in general.

Measuring user involvement: a diffusion of innovation perspective

Abstract: User involvement is a need-based motivational attitude toward information systems and their development. As such, it has important implications for the successful creation and deployment of information systems in organizations. This paper reports on the development and validation of an instrument to determine if the distinction between a user's involvement in the process of information system diffusion can be measured independently of that user's involvement with the information system innovation itself. Utilizing previously-validated instruments from consumer behavior research, these two object-based categories of user involvement were operationalized.A longitudinal field study was conducted of users in a large financial institution during the implementation phase, in particular the later activities of the adaptation stage, of the information system diffusion process. During adaptation, the information system product becomes available for use in the organization. Late adaptation stage activities include hardware installation, system conversion, and training. The instruments were pre-tested and assessed as to their content validity, internal consistency, convergent validity, unidimensionality, temporal stability, discriminant validity, predictive validity, and factorial validity. The evidence indicates that the measurement scales are reliable and valid. The primary question of scale independence was examined by discriminant validity. The empirical evidence supports the theoretical distinction between user process involvement and user system involvement. The implications of these findings to research and practice are discussed.

Gender, sexual orientation, and disordered eating

Abstract: While most patients with bulimia nervosa are heterosexual women, a significant number of men with bulimia nervosa are gay males, suggesting that gay men, more than heterosexual men, may be at risk for developing eating disorders. This study compared the food-related attitudes and behaviors of heterosexual men and women in contrast with those of lesbians and gay men, attempting to find whether one's sexual orientation may contribute to differential risk. Two thousand employees were randomly selected from a large health care corporation, of whom 805 returned a completed questionnaire including Stunkard and Messick's (1985) Dietary Restraint and Disinhibition Scales. A stratified random sample was drawn to include demographically comparable groups of 25 lesbians, 50 gay men, 75 heterosexual women, and 75 heterosexual men. Women were less satisfied with their appearance at their present weight and expressed more restraint and more negative feelings after bingeing than did men. Heterosexual women were...

Economic Evaluations, Prime Ministerial Approval and Governing Party Support: Rival Models Reconsidered

Abstract: The argument that personal economic expectations drive support for British governing parties has received wide attention. This article employs aggregate data for the 1979–92 period to assess the effects of personal expectations, other subjective economic variables and evaluations of prime ministerial performance in rival party-support models. Analyses of competing models, including error correction specifications that take into account nonstationarity in the time series of interest, indicate that the personal expectations variants generally do very well, although they do not outperform one or more alternatives incorporating other types of economic evaluations. The error correction models show that the prime minister's approval ratings have significant short-term and long-term effects on governing party popularity.

Parenting stress in parents of children with attention-deficit hyperactivity disorder and parents of children with learning disabilities

Abstract: Parenting a child with ADHD can challenge parenting resources and coping. Increasingly, researchers are examining the relationship between the behavior of the child with ADHD and family functioning. While studies have shown inceased parenting stress in parents of children with ADHD, these studies have compared children with ADHD to non-disabled children. This study compares reports of parenting stress among mothers of children with ADHD, mothers of children with learning disabilities and mothers of non-referred children. Results showed that parenting stress was highest for mothers of children with ADHD. Increased parenting stress was associated with child characteristics and, in particular, with externalizing behavior problems.

The hazards of small firms in Southern Africa

Abstract: Small enterprises are a ubiquitous feature of the economies of many developing countries. This study is the first to examine the duration of their survival using economic theory and modern econometric techniques. Using data sets from surveys conducted in four southern African countries, I estimate a proportional hazards model describing the closure rates of a sample of approximately 21,000 firms. There is an inverse relationship between enterprise growth rates and the closure hazard. The sector where it operates influences the hazard, as does its location. In some countries female‐headed firms are at a survival disadvantage compared to their male counterparts.

Dynamical model for DNA sequences

Abstract: We address the problem of DNA sequences, developing a ``dynamical'' method based on the assumption that the statistical properties of DNA paths are determined by the joint action of two processes, one deterministic with long-range correlations, and the other random and \ensuremath{\delta}-function correlated. The generator of the deterministic evolution is a nonlinear map, belonging to a class of maps recently tailored to mimic the processes of weak chaos that are responsible for the birth of anomalous diffusion. It is assumed that the deterministic process corresponds to unknown biological rules that determine the DNA path, whereas the noise mimics the influence of an infinite-dimensional environment on the biological process under study. We prove that the resulting diffusion process, if the effect of the random process is neglected, is an \ensuremath{\alpha}-stable L\'evy process with 12. We also show that, if the diffusion process is determined by the joint action of the deterministic and the random process, the correlation effects of the ``deterministic dynamics'' are cancelled on the short-range scale, but show up in the long-range one. We denote our prescription to generate statistical sequences as the copying mistake map (CMM). We carry out our analysis of several DNA sequences and their CMM realizations with a variety of techniques, and we especially focus on a method of regression to equilibrium, which we call the Onsager analysis. With these techniques we establish the statistical equivalence of the real DNA sequences with their CMM realizations. We show that long-range correlations are present in exons as well as in introns, but are difficult to detect, since the exon ``dynamics'' is shown to be determined by the entanglement of three distinct and independent CMM's.

Genetic Diversity in a Threatened Wetland Species, Helonias bullata (Liliaceae)

Abstract: Genetic variation was examined in Helonias bullata, a threatened perennial plant species that occurs in isolated wetland habitats. Fifteen populations representing the species’ geographic range were sampled. Genetic diversity was low for the species (Hes = 0.053) as well as within populations (Hep = 0.029). Of the 33 allozyme loci examined, 11 (33%) were polymorphic, while on average only 12.8% (4) of the loci were polymorphic within populations. The number of alleles per polymorphic locus was 2.36 for the species and averaged 2.09 across populations. For every genetic parameter calculated, variation in H. bullata was lower than that typically found for narrowly distributed plant species. The lowest levels of genetic diversity were found in northern areas that were colonized following the last glacial epoch. The number of genotypes detected per population ranged from three to 21, with a mean of 13 for this clonally reproducing species. We found a relatively high proportion of total genetic diversity (30.6%) among populations and a significant correlation (p < 0.002) between genetic distance and geographic distance. Genetic drift phenomena appear to play a major role in the population genetics of this species. Anomalously, several populations that appeared most limited in size and vigor were genetically most variable, perhaps because they represent older, relictual populations. Life-history characteristics of H. bullata coupled with low levels of genetic diversity and the degradation and disappearance of wetlands threaten the existence of this species. Se examino la variabilidad genetica de Helonias bullata, una especie de planta perenne que se da en habitats de humedales aislados. Se muestrearon quince poblaciones que representan el area de distribucion geografica de la especie. La diversidad genetica fue baja tanto para la especie en su totalidad (Hes = 0.053) como para cada poblacion (Hep = 0.029). De los 33 locus de aloenzimas examinados, 11 (33%) fueron polimorficos, mientras que en promedio solo 12.8% (4) de los locus fueron polimorficos dentro de las poblaciones. El numero de alelos por locus polimorfico fue 2.36 para la especie y promedio 2.09 a lo largo de las poblaciones. Para cada parametro genetico calculado, la variacion en H. bullata fue menor que aquella tipica de especies vegetales con una distribucion reducida. Los niveles de diversidad genetica menores fueron encontrados en las areas del norte que fueron colonizadas luego de la era glacial. El numero de genotipos detectados por poblacion vario entre 3 y 21, con una media de 13 para esta especie que se reproduce clonalmente. Una proporcion alta de la diversidad genetica total (30.6%) se debio a la variabilidad entre poblaciones y se encontro una correlacion significativa (P < 0.002) entre la distancia genetica y la distancia geografica. El fenomeno de deriva genetica parece jugar un rol importante en la genetica poblacional de esta especie. En forma inesperada, varias poblaciones que parecian mas limitadas en tamano y vigor fueron las mas variables geneticamente, posiblemente porque ellas representan poblaciones relictas mas antiguas. Las caracteristicas de la historia natural de H. bullata juntamente con los bajos niveles de diversidad genetica y la degradacion y desaparicion de humedales ponen en peligro la existencia de esta especie.

Informed trading risk and bid‐ask spread changes around open market stock repurchases in the nasdaq market

Abstract: Microstructure theory contends that dealers' bid-ask spreads should vary intertemporally with changes in the asymmetric information component of the spread. Corporate theory suggests that stock repurchase announcements signal management's private information to the securities markets. An examination of dealers' spread behavior around firms' open market repurchases in the NASDAQ market reveals a decline in spreads adjusted for dealers' inventory-holding and order-processing costs. This decline is attributed to a reduction in informed trading risk associated with the open market repurchase announcements.

“Et in Amygdala Ego”?: UG, (S)LA, and Neurobiology

Abstract: John Schumann and colleagues (Jacobs, 1988; Jacobs & Schumann, 1992; Pulvermuller & Schumann, 1994; Schumann, 1990a, 1990b) have argued for a neurobiological perspective on language acquisition, one that denies a role for a specifically linguistic mental module of the sort proposed by, for example, Chomsky (eg, 1986) In this paper, we challenge this perspective by offering evidence that such a mental module must be involved in the acquisition of grammatical competence