Showing papers by "University of Connecticut published in 2005"

The integrative review: updated methodology

Abstract: Aim. The aim of this paper is to distinguish the integrative review method from other review methods and to propose methodological strategies specific to the integrative review method to enhance the rigour of the process. Background. Recent evidence-based practice initiatives have increased the need for and the production of all types of reviews of the literature (integrative reviews, systematic reviews, meta-analyses, and qualitative reviews). The integrative review method is the only approach that allows for the combination of diverse methodologies (for example, experimental and non-experimental research), and has the potential to play a greater role in evidence-based practice for nursing. With respect to the integrative review method, strategies to enhance data collection and extraction have been developed; however, methods of analysis, synthesis, and conclusion drawing remain poorly formulated. Discussion. A modified framework for research reviews is presented to address issues specific to the integrative review method. Issues related to specifying the review purpose, searching the literature, evaluating data from primary sources, analysing data, and presenting the results are discussed. Data analysis methods of qualitative research are proposed as strategies that enhance the rigour of combining diverse methodologies as well as empirical and theoretical sources in an integrative review. Conclusion. An updated integrative review method has the potential to allow for diverse primary research methods to become a greater part of evidence-based practice initiatives.

Level set evolution without re-initialization: a new variational formulation

Abstract: In this paper, we present a new variational formulation for geometric active contours that forces the level set function to be close to a signed distance function, and therefore completely eliminates the need of the costly re-initialization procedure. Our variational formulation consists of an internal energy term that penalizes the deviation of the level set function from a signed distance function, and an external energy term that drives the motion of the zero level set toward the desired image features, such as object boundaries. The resulting evolution of the level set function is the gradient flow that minimizes the overall energy functional. The proposed variational level set formulation has three main advantages over the traditional level set formulations. First, a significantly larger time step can be used for numerically solving the evolution partial differential equation, and therefore speeds up the curve evolution. Second, the level set function can be initialized with general functions that are more efficient to construct and easier to use in practice than the widely used signed distance function. Third, the level set evolution in our formulation can be easily implemented by simple finite difference scheme and is computationally more efficient. The proposed algorithm has been applied to both simulated and real images with promising results.

The new higher level classification of eukaryotes with emphasis on the taxonomy of protists

Abstract: This revision of the classification of unicellular eukaryotes updates that of Levine et al. (1980) for the protozoa and expands it to include other protists. Whereas the previous revision was primarily to incorporate the results of ultrastructural studies, this revision incorporates results from both ultrastructural research since 1980 and molecular phylogenetic studies. We propose a scheme that is based on nameless ranked systematics. The vocabulary of the taxonomy is updated, particularly to clarify the naming of groups that have been repositioned. We recognize six clusters of eukaryotes that may represent the basic groupings similar to traditional ''kingdoms.'' The multicellular lineages emerged from within monophyletic protist lineages: animals and fungi from Opisthokonta, plants from Archaeplastida, and brown algae from Stramenopiles.

Prosocial Behavior: Multilevel Perspectives

Abstract: Current research on prosocial behavior covers a broad and diverse range of phenomena. We argue that this large research literature can be best organized and understood from a multilevel perspective. We identify three levels of analysis of prosocial behavior: (a) the “meso” level—the study of helper-recipient dyads in the context of a specific situation; (b) the micro level—the study of the origins of prosocial tendencies and the sources of variation in these tendencies; and (c) the macro level—the study of prosocial actions that occur within the context of groups and large organizations. We present research at each level and discuss similarities and differences across levels. Finally, we consider ways in which theory and research at these three levels of analysis might be combined in future intra- and interdisciplinary research on prosocial behavior.

The Actor–Partner Interdependence Model: A model of bidirectional effects in developmental studies:

Abstract: The actor-partner interdependence model (APIM) is a model of dyadic relationships that integrates a conceptual view of interdependence with the appropriate statistical techniques for measuring and testing it. In this article we present the APIM as a general, longitudinal model for measuring bidirectional effects in interpersonal relationships. We also present three different approaches to testing the model. The statistical analysis of the APIM is illustrated using longitudinal data on relationship specific attachment security from 203 mother-adolescent dyads. The results support the view that interpersonal influence on attachment security is bidirectional. Moreover, consistent with a hypothesis from attachment theory, the degree to which a child's attachment security is influenced by his or her primary caregiver is found to diminish with age.

Incorporating contextual information in recommender systems using a multidimensional approach

Abstract: The article presents a multidimensional (MD) approach to recommender systems that can provide recommendations based on additional contextual information besides the typical information on users and items used in most of the current recommender systems. This approach supports multiple dimensions, profiling information, and hierarchical aggregation of recommendations. The article also presents a multidimensional rating estimation method capable of selecting two-dimensional segments of ratings pertinent to the recommendation context and applying standard collaborative filtering or other traditional two-dimensional rating estimation techniques to these segments. A comparison of the multidimensional and two-dimensional rating estimation approaches is made, and the tradeoffs between the two are studied. Moreover, the article introduces a combined rating estimation method, which identifies the situations where the MD approach outperforms the standard two-dimensional approach and uses the MD approach in those situations and the standard two-dimensional approach elsewhere. Finally, the article presents a pilot empirical study of the combined approach, using a multidimensional movie recommender system that was developed for implementing this approach and testing its performance.

Tamoxifen for the Prevention of Breast Cancer: Current Status of the National Surgical Adjuvant Breast and Bowel Project P-1 Study

Abstract: Background: Initial fi ndings from the National Surgical Adjuvant Breast and Bowel Project Breast Cancer Prevention Trial (P-1) demonstrated that tamoxifen reduced the risk of estrogen receptor – positive tumors and osteoporotic fractures in women at increased risk for breast cancer. Side effects of varying clinical signifi cance were observed. The trial was unblinded because of the positive results, and follow-up continued. This report updates our initial fi ndings. Methods: Women (n = 13 388) were randomly assigned to receive placebo or tamoxifen for 5 years. Rates of breast cancer and other events were compared by the use of risk ratios (RRs) and 95% confi dence intervals (CIs). Estimates of the net benefi t from 5 years of tamoxifen therapy were compared by age, race, and categories of predicted breast cancer risk. Statistical tests were two-sided. Results: After 7 years of follow-up, the cumulative rate of invasive breast cancer was reduced from 42.5 per 1000 women in the placebo group to 24.8 per 1000 women in the tamoxifen group (RR = 0.57, 95% CI = 0.46 to 0.70) and the cumulative rate of noninvasive breast cancer was reduced from 15.8 per 1000 women in the placebo group to 10.2 per 1000 women in the tamoxifen group (RR = 0.63, 95% CI = 0.45 to 0.89). These reductions were similar to those seen in the initial report. Tamoxifen led to a 32% reduction in osteoporotic fractures (RR = 0.68, 95% CI = 0.51 to 0.92). Relative risks of stroke, deep-vein thrombosis, and cataracts (which increased with tamoxifen) and of ischemic heart disease and death (which were not changed with tamoxifen) were also similar to those initially reported. Risks of pulmonary embolism were approximately 11% lower than in the original report, and risks of endometrial cancer were about 29% higher, but these differences were not statistically signifi cant. The net benefi t achieved with tamoxifen varied according to age, race, and level of breast cancer risk. Conclusions: Despite the potential bias caused by the unblinding of the P-1 trial, the magnitudes of all benefi cial and undesirable treatment effects of tamoxifen were similar to those initially reported, with notable reductions in breast cancer and increased risks of thromboem bolic events and endometrial cancer. Readily identifi able sub sets of individuals comprising 2.5 million women could derive a net benefi t from the drug. [J Natl Cancer Inst 2005;97:1652 – 62]

Hormonal Responses and Adaptations to Resistance Exercise and Training

Abstract: Resistance exercise has been shown to elicit a significant acute hormonal response. It appears that this acute response is more critical to tissue growth and remodelling than chronic changes in resting hormonal concentrations, as many studies have not shown a significant change during resistance training despite increases in muscle strength and hypertrophy. Anabolic hormones such as testosterone and the superfamily of growth hormones (GH) have been shown to be elevated during 15-30 minutes of post-resistance exercise providing an adequate stimulus is present. Protocols high in volume, moderate to high in intensity, using short rest intervals and stressing a large muscle mass, tend to produce the greatest acute hormonal elevations (e.g. testosterone, GH and the catabolic hormone cortisol) compared with low-volume, high-intensity protocols using long rest intervals. Other anabolic hormones such as insulin and insulin-like growth factor-1 (IGF-1) are critical to skeletal muscle growth. Insulin is regulated by blood glucose and amino acid levels. However, circulating IGF-1 elevations have been reported following resistance exercise presumably in response to GH-stimulated hepatic secretion. Recent evidence indicates that muscle isoforms of IGF-1 may play a substantial role in tissue remodelling via up-regulation by mechanical signalling (i.e. increased gene expression resulting from stretch and tension to the muscle cytoskeleton leading to greater protein synthesis rates). Acute elevations in catecholamines are critical to optimal force production and energy liberation during resistance exercise. More recent research has shown the importance of acute hormonal elevations and mechanical stimuli for subsequent up- and down-regulation of cytoplasmic steroid receptors needed to mediate the hormonal effects. Other factors such as nutrition, overtraining, detraining and circadian patterns of hormone secretion are critical to examining the hormonal responses and adaptations to resistance training.

Quality Indicators for Group Experimental and Quasi-Experimental Research in Special Education:

Abstract: This article presents quality indicators for experimental and quasi-experimental studies for special education. These indicators are intended not only to evaluate the merits of a completed research report or article but also to serve as an organizer of critical issues for consideration in research. We believe these indicators can be used widely, from assisting in the development of research plans to evaluating proposals. In this article, the framework and rationale is explained by providing brief descriptions of each indicator. Finally, we suggest a standard for determining whether a practice may be considered evidence-based. It is our intent that this standard for evidenced-based practice and the indicators be reviewed, revised as needed, and adopted by the field of special education.

Horizontal gene transfer, genome innovation and evolution

Abstract: To what extent is the tree of life the best representation of the evolutionary history of microorganisms? Recent work has shown that, among sets of prokaryotic genomes in which most homologous genes show extremely low sequence divergence, gene content can vary enormously, implying that those genes that are variably present or absent are frequently horizontally transferred. Traditionally, successful horizontal gene transfer was assumed to provide a selective advantage to either the host or the gene itself, but could horizontally transferred genes be neutral or nearly neutral? We suggest that for many prokaryotes, the boundaries between species are fuzzy, and therefore the principles of population genetics must be broadened so that they can be applied to higher taxonomic categories.

To Empower or Not to Empower Your Sales Force? An Empirical Examination of the Influence of Leadership Empowerment Behavior on Customer Satisfaction and Performance

Abstract: This research focuses on the impact of leadership empowerment behavior (LEB) on customer service satisfaction and sales performance, as mediated by salespeople’s self-efficacy and adapt ability. Moreover, the authors propose an interactive relationship whereby LEB will be differentially effective as a function of employees’ empowerment readiness. The authors’ hypotheses are tested using survey data from a sample of 231 salespeople in the pharmaceutical field, along with external ratings of satisfaction from 864 customers and archival sales performance information. Results indicated that contrary to popular belief, employees with low levels of product/industry knowledge and low experience benefit the most from leadership behaviors that are empowering, whereas high-knowledge and experienced employees reap no clear benefit. The authors conclude with directions for future research and application.

Religion as a Meaning‐Making Framework in Coping with Life Stress

Abstract: This article explores how religion, as a meaning system, influences coping with adversity. First, a model emphasizing the role of meaning making in coping is presented. Next, religion as a meaning system is defined, and theory and research on the role of religion in the coping process are summarized. Results from the author's study of 169 bereaved college students are then presented to illustrate some of the pathways through which religious meaning can influence the coping process in making meaning following loss. Findings indicate that associations between religion and adjustment vary across time since loss, and that these associations are mediated by meaning-making coping. Finally, implications for individual and societal well-being and suggestions for future research are discussed.

To Empower or Not to Empower Your Sales Force? An Empirical Examination of the Influence of Leadership Empowerment Behavior on Customer Satisfaction and Performance.

Abstract: This research focuses on the impact of leadership empowerment behavior (LEB) on customer service satisfaction and sales performance, as mediated by salespeople's self-efficacy and adaptability. Moreover, the authors propose an interactive relationship whereby LEB will be differentially effective as a function of employees' empowerment readiness. The authors' hypotheses are tested using survey data from a sample of 231 salespeople in the pharmaceutical field, along with external ratings of satisfaction from 864 customers and archival sales performance information. Results indicated that contrary to popular belief, employees with low levels of product/industry knowledge and low experience benefit the most from leadership behaviors that are empowering, whereas high-knowledge and experienced employees reap no clear benefit. The authors conclude with directions for future research and application.

Balancing Acquisition and Retention Resources to Maximize Customer Profitability

Abstract: In this research, the authors present a modeling framework for balancing resources between customer acquisition efforts and customer retention efforts. The key question that the framework addresses is, “What is the customer profitability maximizing balance?” In addition, they answer questions about how much marketing spending to allocate to customer acquisition and retention and how to distribute those allocations across communication channels.

Attitudes Toward Younger and Older Adults: An Updated Meta‐Analytic Review

Abstract: This meta-analytic review of 232 effect sizes showed that, across five categories, attitudes were more negative toward older than younger adults. Perceived age differences were largest for age stereotypes and smallest for evaluations. As predicted by social role theory (Eagly, 1987), effect sizes were reduced when detailed information was provided about the person being rated. The double standard of aging emerged for evaluations and behavior/behavioral intentions, but was reversed for the competence category. Perceptions depended on respondent age also. Results demonstrated both the multi-dimensionality and the complexity of attitudes toward older adults (Hummert, 1999; Kite & Wagner, 2002).

Bayesian Survival Analysis

Abstract: Great strides in the analysis of survival data using Bayesian methods have been made in the past ten years due to advances in Bayesian computation and the feasibility of such methods. In this chapter, we review Bayesian advances in survival analysis and discuss the various semiparametric modeling techniques that are now commonly used. We review parametric and semiparametric approaches to Bayesian survival analysis, with a focus on proportional hazards models. Reference to other types of models are also given. Keywords: beta process; Cox model; Dirichlet process; gamma process; Gibbs sampling; piecewise exponential model; Weibull model

Adverse events associated with testosterone replacement in middle-aged and older men: a meta-analysis of randomized, placebo-controlled trials

Abstract: Background. We performed a meta-analysis of randomized clinical trials to determine the risks of adverse events associated with testosterone replacement in older men. Methods. The MEDLINE database was searched from 1966 to April 2004, using testosterone as the indexing term; limits included human, male, � 45 years old, and randomized controlled trial. Of the 417 studies thus identified, 19 met the inclusion criteria: testosterone replacement for at least 90 days, men � 45 years old with low or low-normal testosterone level, randomized controlled trial, and medically stable men. Odds ratios (ORs) were pooled using a random effects model, assuming heterogeneous results across studies, and were weighted for sample size. Results. In the 19 studies that met eligibility criteria, 651 men were treated with testosterone and 433 with placebo. The combined rate of all prostate events was significantly greater in testosterone-treated men than in placebo-treated men (OR ¼1.78, 95% confidence interval [CI], 1.07‐2.95). Rates of prostate cancer, prostate-specific antigen (PSA) .4 ng/ml, and prostate biopsies were numerically higher in the testosterone group than in the placebo group, although differences between the groups were not individually statistically significant. Testosterone-treated men were nearly four times as likely to have hematocrit .50% as placebo-treated men (OR ¼3.69, 95% CI, 1.82‐7.51). The frequency of cardiovascular events, sleep apnea or death was not significantly different between the two groups. Conclusions. Testosterone replacement in older men was associated with a significantly higher risk of detection of prostate events and of hematocrit .50% than was placebo; hematocrit increase was the most frequent adverse event associated with testosterone replacement. These data reaffirm the need to monitor hematocrit, PSA, and digital examination of the prostate during testosterone replacement in older men.

DNA-based therapeutics and DNA delivery systems: a comprehensive review.

Abstract: The past several years have witnessed the evolution of gene medicine from an experimental technology into a viable strategy for developing therapeutics for a wide range of human disorders. Numerous prototype DNA-based biopharmaceuticals can now control disease progression by induction and/or inhibition of genes. These potent therapeutics include plasmids containing transgenes, oligonucleotides, aptamers, ribozymes, DNAzymes, and small interfering RNAs. Although only 2 DNA-based pharmaceuticals (an antisense oligonucleotide formulation, Vitravene, (USA, 1998), and an adenoviral gene therapy treatment, Gendicine (China, 2003), have received approval from regulatory agencies; numerous candidates are in advanced stages of human clinical trials. Selection of drugs on the basis of DNA sequence and structure has a reduced potential for toxicity, should result in fewer side effects, and therefore should eventually yield safer drugs than those currently available. These predictions are based on the high selectivity and specificity of such molecules for recognition of their molecular targets. However, poor cellular uptake and rapid in vivo degradation of DNA-based therapeutics necessitate the use of delivery systems to facilitate cellular internalization and preserve their activity. This review discusses the basis of structural design, mode of action, and applications of DNA-based therapeutics. The mechanisms of cellular uptake and intracellular trafficking of DNA-based therapeutics are examined, and the constraints these transport processes impose on the choice of delivery systems are summarized. Finally, the development of some of the most promising currently available DNA delivery platforms is discussed, and the merits and drawbacks of each approach are evaluated.

Bacterial Swimming and Oxygen Transport Near Contact Lines

Abstract: Aerobic bacteria often live in thin fluid layers near solid–air–water contact lines, in which the biology of chemotaxis, metabolism, and cell–cell signaling is intimately connected to the physics of buoyancy, diffusion, and mixing. Using the geometry of a sessile drop, we demonstrate in suspensions of Bacillus subtilis the self-organized generation of a persistent hydrodynamic vortex that traps cells near the contact line. Arising from upward oxygentaxis and downward gravitational forcing, these dynamics are related to the Boycott effect in sedimentation and are explained quantitatively by a mathematical model consisting of oxygen diffusion and consumption, chemotaxis, and viscous fluid dynamics. The vortex is shown to advectively enhance uptake of oxygen into the suspension, and the wedge geometry leads to a singularity in the chemotactic dynamics near the contact line.

The effects of parental altruism on the governance of family-managed firms

Abstract: We draw on the economic, corporate governance, and family business literatures to explain why the effects of family on family firms makes this governance form theoretically distinct from those of public and private non-family firms. Our thesis is that parental altruism, when combined with private ownership and owner-management, influences the ability of the firm's owner-manager to exercise self-control, which, in turn, can expose some family firms to conflicts rooted in the agency threats of moral hazard, hold-up, and adverse selection. We then discuss why some other family firms are able to minimize these dark side threats and thereby attain altruism's brighter side. Finally, we discuss how altruism's influence changes over time as ownership becomes dispersed among family members and across generations. Copyright © 2005 John Wiley & Sons, Ltd.

Queuing with adaptive modulation and coding over wireless links: cross-Layer analysis and design

Abstract: Assuming there are always sufficient data waiting to be transmitted, adaptive modulation and coding (AMC) schemes at the physical layer have been traditionally designed separately from higher layers. However, this assumption is not always valid when queuing effects are taken into account at the data link layer. In this paper, we analyze the joint effects of finite-length queuing and AMC for transmissions over wireless links. We present a general analytical procedure, and derive the packet loss rate, the average throughput, and the average spectral efficiency (ASE) of AMC. Guided by our performance analysis, we introduce a cross-layer design, which optimizes the target packet error rate of AMC at the physical layer, to minimize thpacket loss rate and maximize the average throughput, when combined with a finite-length queue at the data link layer. Numerical results illustrate the dependence of system performance on various parameters, and quantify the performance gain due to cross-layer optimization. Our focus is on the single user case, but we also discuss briefly possible applications to multiuser scenarios.