Showing papers by "University of North Carolina at Charlotte published in 2000"

A correlational test of the relationship between posttraumatic growth, religion, and cognitive processing.

Abstract: The present study examined the degree to which event related rumination, a quest orientation to religion, and religious involvement is related to posttraumatic growth. Fifty-four young adults, selected based on prescreening for experience of a traumatic event, completed a measure of event related ruminations, the Quest Scale, an index of religious participation, and the Posttraumatic Growth Inventory. The three subscales of the Quest Scale, the two groups of rumination items (soon after event/within past two weeks), and the index of religious participation were entered in a standard multiple regression with the total score of the Posttraumatic Growth Inventory as the dependent variable. The degree of rumination soon after the event and the degree of openness to religious change were significantly related to Posttraumatic Growth. Congruent with theoretical predictions, more rumination soon after the event, and greater openness to religious change were related to more posttraumatic growth. Present findings offer some confirmation of theoretical predictions, and also offer clear direction for further research on the relationships of religion, rumination, and posttraumatic growth.

Functional-Coefficient Regression Models for Nonlinear Time Series

Abstract: The local linear regression technique is applied to estimation of functional-coefficient regression models for time series data. The models include threshold autoregressive models and functional-coefficient autoregressive models as special cases but with the added advantages such as depicting finer structure of the underlying dynamics and better postsample forecasting performance. Also proposed are a new bootstrap test for the goodness of fit of models and a bandwidth selector based on newly defined cross-validatory estimation for the expected forecasting errors. The proposed methodology is data-analytic and of sufficient flexibility to analyze complex and multivariate nonlinear structures without suffering from the “curse of dimensionality.” The asymptotic properties of the proposed estimators are investigated under the α-mixing condition. Both simulated and real data examples are used for illustration.

Role-based authorization constraints specification

Abstract: Constraints are an important aspect of role-based access control (RBAC) and are often regarded as one of the principal motivations behind RBAC. Although the importance of contraints in RBAC has been recogni zed for a long time, they have not recieved much attention. In this article, we introduce an intuitive formal language for specifying role-based authorization constraints named RCL 2000 including its basic elements, syntax, and semantics. We give soundness and completeness proofs for RCL 2000 relative to a restricted form of first-order predicate logic. Also, we show how previously identified role-based authorization constraints such as separtation of duty (SOD) can be expressed in our language. Moreover, we show there are other significant SOD properties that have not been previously identified in the literature. Our work shows that there are many alternate formulations of even the simplest SOD properties, with varying degree of flexibility and assurance. Our language provides us a rigorous foundation for systematic study of role-based authorization constraints.

Efficient Estimation and Inferences for Varying-Coefficient Models

Abstract: This article deals with statistical inferences based on the varying-coefficient models proposed by Hastie and Tibshirani. Local polynomial regression techniques are used to estimate coefficient functions, and the asymptotic normality of the resulting estimators is established. The standard error formulas for estimated coefficients are derived and are empirically tested. A goodness-of-fit test technique, based on a nonparametric maximum likelihood ratio type of test, is also proposed to detect whether certain coefficient functions in a varying-coefficient model are constant or whether any covariates are statistically significant in the model. The null distribution of the test is estimated by a conditional bootstrap method. Our estimation techniques involve solving hundreds of local likelihood equations. To reduce the computational burden, a one-step Newton-Raphson estimator is proposed and implemented. The resulting one-step procedure is shown to save computational cost on an order of tens with no...

Onset age, persistence, and offending versatility: comparisons across gender*

Abstract: Offending specialization has received considerable attention in past research on criminal careers. Relatively little attention has been given to examining the relationships between various sub-group differences and the extent to which individuals tend toward specialization or versatility in their criminal careers. In the present analysis, we examine hypotheses derived from Moffitt's recent developmental theory that bear directly on offending specialization. Our analysis examines direct relationships between gender, onset age, persistence and offending specialization as well as the interaction of these influences and offending specialization. Our findings reveal results that are both consistent and inconsistent with Moffitt's dual taxonomy of offending behavior.

Adaptive Varying-Coefficient Linear Models

Abstract: Varying-coefficient linear models arise from multivariate nonparametric regression, nonlinear time series modelling and forecasting, functional data analysis, longitudinal data analysis, and others. It has been a common practice to assume that the vary-coefficients are functions of a given variable which is often called an index. A frequently asked question is which variable should be used as the index. In this paper, we explore the class of the varying-coefficient linear models in which the index is unknown and is estimated as a linear combination of regression and/or other variables. This will enlarge the modelling capacity substantially. We search for the index such that the derived varying-coefficient model provides the best approximation to the underlying unknown multi-dimensional regression function in the least square sense. The search is implemented through the newly proposed hybrid backfitting algorithm. The core of the algorithm is the alternative iteration between estimating the index through a one-step scheme and estimating coefficient functions through a one-dimensional local linear smoothing. The generalised cross-validation method for choosing bandwidth is efficiently incorporated into the algorithm. The locally significant variables are selected in terms of the combined use of t-statistic and Akaike information criterion. We further extend the algorithm for the models with two indices. Simulation shows that the proposed methodology has appreciable flexibility to model complex multivariate nonlinear structure and is practically feasible with average modern computers. The methods are further illustrated through the Canadian mink-muskrat data in 1925-1994 and the pound/dollar exchange rates in 1974-1983.

The long-range scanning stage: a novel platform for scanned-probe microscopy

Abstract: This paper describes a magnetically suspended six degree-of-freedom precision motion control stage with a horizontal positioning noise of less than 0.6 nm three sigma. The vertical positioning noise is less than 2.2 nm three sigma. The stage utilizes four levitation linear motors to suspend and servo the moving element (platen) throughout its 25 mm × 25 mm × 0.1 mm range of travel. Position feedback is provided by three plane mirror interferometers and three capacitance probes. The suspended platen (12 kg mass) is floated in oil to enhance the stage’s disturbance rejection and to reduce power dissipation in the actuators. The stage has been designed to achieve a positioning accuracy of 10 nm and is used to position samples beneath a scanned probe microscope. The ultimate purpose of this measuring machine is to provide a means of measuring submicron-scale features with nanometer-scale accuracy. The technology can easily be scaled to larger travels, with accuracy limited primarily by the wavelength instability of the HeNe light source. This article gives an overview of the LORS project, emphasizing the system error terms, tolerancing, and experimental results.

Action-Rules: How to Increase Profit of a Company

Abstract: Decision tables classifying customers into groups of different profitability are used for mining rules classifying customers. Attributes are divided into two groups: stable and flexible. By stable attributes we mean attributes which values can not be changed by a bank (age, marital status, number of children are the examples). On the other hand attributes (like percentage rate or loan approval to buy a house in certain area) which values can be changed or influenced by a bank are called flexible. Rules are extracted from a decision table given preference to flexible attributes. This new class of rules forms a special repository of rules from which new rules called actionrules are constructed. They show what actions should be taken to improve the profitability of customers.

An empirical study of stalking victimization.

Abstract: This article empirically studies the phenomenon of stalking and its victims by utilizing a random sample of college students at a large public University. The study found that 25% of the women and 11% of the men had been stalked at some point in their lives and that six percent were currently being stalked. Additionally, the study found that the majority of stalking victims are women who are stalked by male offenders. The sample reported being stalked for an average of 347 days and having engaged in a variety of actions in response. A substantial number of victims reported being threatened by their stalkers. This threat was associated with higher levels of fear among the victims and a greater chance of physical attack by the stalkers, particularly for the female victims.

Enhanced biocompatible implants and alloys

Abstract: The invention provides improved biocompatible implant alloys and methods of constructing artificial implants having improved long term wear properties. Cobalt-base biocompatible implant alloys provided according to the invention are essentially free of carbide, nitride and sigma second phase particles, and can have hardness and strength properties equivalent to or greater than the standard CoCrMo alloy with significantly improved fatigue life and superior frictional contact properties with UHMWPE. Artificial implant constructions and methods provided according to another aspect of the invention are capable of eliminating latent defects that can promote long term failure of joint implants.

The Public Health Significance of Viable but Nonculturable Bacteria

Abstract: A bacterium in the viable but nonculturable (VBNC) state is defined here as a cell which fails to grow on the routine bacteriological media on which it would normally grow and develop into a colony, but which is in fact alive and capable of metabolic activity. The term “nonculturable” seems to be a misnomer as, under the proper conditions, it appears that these cells are able to “resuscitate” to the metabolically active and culturable state (this point, along with a brief discussion on why cells enter this state of dormancy, is presented later in this chapter). In this review, the discussion of cells entering the VBNC state is limited to those cells which respond to a natural environmental stress (e.g., a temperature downshift) in such a manner. Thus, this review does not include a discussion of the detrimental effects of such agents as antibiotics, chlorine, heavy metals, or other chemicals to which cells may be exposed and which may result in cell injury or death (this area is reviewed in chapter 15). Similarly, this review does not describe cells that are most correctly termed “nonculturable,” e.g., those animal symbionts which have never been cultured in the laboratory. Such cells are described in chapter 5. Instead, this chapter is limited to a discussion of human bacterial pathogens which are known to enter the VBNC state. Finally, I have for the most part selected to review only those studies which have employed such methods as the “direct viable count” originally described by Kogure et al. (38), p-iodonitrotetrazolium violet (INT) reduction (86), or 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) hydrolysis (64) to demonstrate viability in cells no longer culturable. These methods have been described in an earlier review on the VBNC state (49), as well as in other chapters of this monograph. Despite these restrictions, bacterial cells from at least 16 different genera, mostly but not exclusively gram negative, comprising over 30 different species, have now been reported to enter the VBNC state (50).

Content analysis of Fortune 100 company Web sites

Abstract: Discusses the results of content analysis of the Web sites of Fortune 100 companies, carried out to identify the mix of promotional activities on their Web sites. Specifically, we performed a content analysis of Web sites utilizing categories representing a range of marketing communications, including: communicating product, pricing and dealer/retail location information, related and unrelated advertisements, sales promotion, direct marketing, basic company information and public relations. We also identified differences between and among industries based on standard industrial classification (SIC) codes. We found considerable variability in how members of the Fortune 100 used their Web sites. The Web sites ranged from very simple ones that focused on basic company information, such as company history, to quite complex Web sites that incorporated a mix of promotional elements, such as press releases, advertisements, games, free gifts and pricing information.

State Definitions for the Gifted and Talented Revisited

Abstract: Definitions of gifted and talented students have been in a state of evolution for some time. Many states rely on the federal interpretation as a guideline for establishing their definitions relating to gifted education. However, the federal definition has gone through a series of metamorphoses with the addition and deletion of various terms and components. This article presents a brief history of the transition of the federal definition for students who are gifted and talented, as well as a description of other definitions that have impacted state definitions. An overview of state definitions in 1990 and 1998 is also presented and analyzed.

Relations between Deprivation and Immigrant Groups in Large Canadian Cities

Abstract: With the co-existence of social polarisation and unprecedented immigration during recent years in major Canadian cities, this paper examines relationships between urban deprivation and the immigrant population in 1991, compared with 1971, the end of the era of the 'old' migration. Census tracts in Toronto, Montreal and Vancouver that experienced multiple deprivation are identified. Only two tracts in all three cities displayed the full set of indicators in 1991, and none in 1971. Indicators neither overlap, nor are as spatially contained, nor are as stable over time as has been true for cities in the US. Like northern Europe, there is evidence of a suburbanisation of deprivation, linked in particular to the diffusion of state-subsidised housing, especially in Toronto. In addition, and also like Europe, there are positive relationships with immigrant populations. But these relations are modest, and affect primarily recent arrivals and non-English-speaking groups. The implications of immigration are complex...

Neurocognitive Functioning and Magnetic Resonance Imaging in Children With Sickle Cell Disease

Abstract: Objective: To examine neurocognitive functioning in children classified with overt cerebral vascular accidents (CVAs), silent infarcts, or without central nervous system (CNS) pathology on magnetic resonance imaging. Methods: Participants were 63 children and adolescents with sickle cell disease (SCD). Results: Children with overt CVAs and silent infarcts differed from their peers without CNSpathology on measures of attention and executive functioning. Conclusions: We consider these deficits the result of the high frequency of frontal lobe deficits incurred by children with SCD. Recommendations include the use of tests designed to measure attention and executive functioning as a way of screening children with SCD for possible CNS pathology. We also suggest that future research examine the mechanism underlying frontal lobe involvement for individuals with SCD.

Effect of starvation and the viable-but-nonculturable state on green fluorescent protein (GFP) fluorescence in GFP-tagged Pseudomonas fluorescens A506.

Abstract: The green fluorescent protein (GFP) gene, gfp, of the jellyfish Aequorea victoria is being used as a reporter system for gene expression and as a marker for tracking prokaryotes and eukaryotes. Cells that have been genetically altered with the gfp gene produce a protein that fluoresces when it is excited by UV light. This unique phenotype allows gfp-tagged cells to be specifically monitored by nondestructive means. In this study we determined whether a gfp-tagged strain of Pseudomonas fluorescens continued to fluoresce under conditions under which the cells were starved, viable but nonculturable (VBNC), or dead. Epifluorescent microscopy, flow cytometry, and spectrofluorometry were used to measure fluorescence intensity in starved, VBNC, and dead or dying cells. Results obtained by using flow cytometry indicated that microcosms containing VBNC cells, which were obtained by incubation under stress conditions (starvation at 37.5°C), fluoresced at an intensity that was at least 80% of the intensity of nonstressed cultures. Similarly, microcosms containing starved cells incubated at 5 and 30°C had fluorescence intensities that were 90 to 110% of the intensity of nonstressed cells. VBNC cells remained fluorescent during the entire 6-month incubation period. In addition, cells starved at 5 or 30°C remained fluorescent for at least 11 months. Treatment of the cells with UV light or incubation at 39 or 50°C resulted in a loss of GFP from the cells. There was a strong correlation between cell death and leakage of GFP from the cells, although the extent of leakage varied depending on the treatment. Most dead cells were not GFP fluorescent, but a small proportion of the dead cells retained some GFP at a lower concentration than the concentration in live cells. Our results suggest that gfp-tagged cells remain fluorescent following starvation and entry into the VBNC state but that fluorescence is lost when the cells die, presumably because membrane integrity is lost.

The Therapeutic Factors Inventory: Development of a scale.

Abstract: Although Yalom’s (1995) framework of the “therapeutic factors” facilitating outcome in group has been accepted by group specialists, no empirically based instrument assesses all of these factors The Therapeutic Factors Inventory (TFI), with 11 scales based on the therapeutic factors, has been designed to fill this gap This article summarizes the development and preliminary reliability testing of the TFI Each scale of the instrument demonstrated high internal consistency; however, one scale obtained unacceptably low test-retest reliability Further validity testing is needed Implications of these findings are discussed

Methane oxidation and microbial exopolymer production in landfill cover soil.

Abstract: In laboratory simulations of methane oxidation in landfill cover soil, methane consumption consistently increased to a peak value and then declined to a lower steady-state value. It was hypothesized that a gradual accumulation of exopolymeric substances (EPS) contributed to decreased methane uptake by clogging soil pores or limiting gas diffusion. This study was conducted to detect and quantify EPS in soil from columns sparged with synthetic landfill gas and from fresh landfill cover cores. Polysaccharide accumulations were detected with alcian blue stain. EPS was observed adhering to soil particles and as strands associated with, but separate from soil grains. Glucose concentrations in laboratory soil columns averaged 426 mg kg−1 dry soil, while in a column sparged with air the average glucose concentration in a horizon was 3.2 mg glucose kg−1 dry soil. Average glucose concentrations in two of four cores sampled from a closed landfill ranged from 600–1100 mg kg−1 dry soil, while control cores averaged 38 mg glucose kg−1 dry soil. Viscosity due to EPS was measured by comparing filtration rates of soil suspensions. Soil extracts from the upper horizons of laboratory columns sparged with landfill gas filtered at about one-third the rate of extracts from the lower horizons, and the landfill core with the highest glucose content also produced highly viscous extracts. Breakthrough curves measured in columns before and after methane exposure were similar, so that short-circuiting due to clogging was not occurring. The data support the hypothesis that EPS impeded oxygen diffusion to an active biofilm and limited the extent of methane oxidation.

The Role of Uncertainty in Investment: An Examination of Competing Investment Models Using Commercial Real Estate Data

Abstract: Neoclassical investment decision criteria suggest that only the systematic component of total risk affects the rate of investment, as channeled through the built-asset price. Alternatively, option-based investment models suggest a direct role for total uncertainty in investment decisionmaking. To sort out uncertainty's role in investment, we specify and empirically estimate a structural model of asset-market equilibrium. Commercial real estate time-series data with two distinct measures of asset price and uncertainty are used to assess the competing investment models. Empirical results generally favor predictions of the option-based model and hence suggest that irreversibility and delay are important considerations to investors. Our findings also have implications for macroeconomic policy and for forecasts of cyclical investment activity.

Depression and Parentification among Adults as Related to Parental Workaholism and Alcoholism.

Abstract: Investigators examined relationships among levels of depression and parentification in undergraduate university students. Instrument scores were used to identify participants as (a) adult children with alcoholic parents, (b) adult children with workaholic parents, (c) adult children with at least one parent who was both alcoholic and workaholic, and (d) a comparison group composed of adult children who met none of the other group criteria. Children of workaholics scored significantly higher on measures of depression and parentification, and they reported parents worked more hours than did parents of children of alcoholics and the comparison group. Children of alcoholics scored significantly higher than the comparison group on the measure of parentification. Children with parents who met both descriptions scored significantly higher than children of alcoholics and the comparison group on the three dimensions described and on combined number of hours both parents worked.

WHEN DO IDEAS MATTER? Explaining the Successes and Failures of Thatcherite Ideas

Abstract: The field of comparative politics has begun to take seriously the role of ideas in politics, but to date this interest has not clearly specified the conditions under which ideas influence public pol- icy. The author develops an integrated framework that shows ideas about policy goals and instru- ments are most influential when they do not attract substantial opposition from voters and inter- est groups and when political institutions concentrate decision-making authority. The author tests this framework by examining the fates of three ideas, facing different degrees of societal opposition and concentrated authority, adopted by the first Thatcher government in Britain.

Test-case generator for nonlinear continuous parameter optimization techniques

Abstract: The experimental results reported in many papers suggest that making an appropriate a priori choice of an evolutionary method for a nonlinear parameter optimization problem remains an open question. It seems that the most promising approach at this stage of research is experimental, involving the design of a scalable test suite of constrained optimization problems, in which many features could be tuned easily. It would then be possible to evaluate the merits and drawbacks of the available methods, as well as to test new methods efficiently. In this paper, we propose such a test-case generator for constrained parameter optimization techniques. This generator is capable of creating various test problems with different characteristics including: 1) problems with different relative sizes of the feasible region in the search space; 2) problems with different numbers and types of constraints; 3) problems with convex or nonconvex evaluation functions, possibly with multiple optima; and 4) problems with highly nonconvex constraints consisting of (possibly) disjoint regions. Such a test-case generator is very useful for analyzing and comparing different constraint-handling techniques.

Intracellular Staphylococcus aureus induces apoptosis in mouse osteoblasts.

Abstract: Staphylococcus aureus invades osteoblasts and is the primary cause of osteomyelitis. This study examined the ability of S. aureus to induce apoptosis in a mouse osteoblast cell line. The presence of intracellular S. aureus was demonstrated by transmission electron microscopy. Light microscopy was utilized to examine morphological changes in the osteoblasts following killing of extracellular bacteria. Cell rounding was observed, and dark centers due to condensation of chromatin were noted in cells in infected osteoblast cultures. DNA was isolated from infected osteoblast cultures, and electrophoresis revealed the laddering effect characteristic of cells undergoing apoptosis. Additionally, an in situ cell death detection assay was utilized to label apoptosis-induced DNA strand breaks. Apoptotic nuclei were present, providing further evidence that S. aureus induces apoptosis in osteoblasts.

A frequency domain method for the measurement of nonlinearity in heterodyne interferometry

Abstract: This paper presents a method for the measurement of nonlinearity in heterodyne interferometry which utilizes the frequency spectrum of the output of the photodetector for the direct measurement of the magnitudes of the first and second harmonic nonlinearities. The underlying theory and the experimental technique are discussed. Results showing the application of this technique for the determination of the influence of the azimuthal alignments of the polarization beamsplitter, the analyzer and measurement retroreflector are presented. The applicability of the technique to the in situ optimization of an interferometer system is demonstrated. It is shown that using this technique an interferometer system can be optimized to reduce the first-harmonic nonlinearity to below 0.5 nm p-p and the second harmonic nonlinearity to 2 nm p-p. This method is contrasted with other methods and the advantages conferred by the elimination of an external reference and the phase measuring electronics are highlighted.