bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Social Support on Chronic Illness Self-Management: A Review and Directions for Research
Authors: Gallant Mary P.
Published: April 2003

A review of the empirical literature examining the relationship between social support and chronic illness self-management identified 29 articles, of which 22 were quantitative and 7 were qualitative. The majority of research in this area concerns diabetes self-management, with a few studies examining asthma, heart disease, and epilepsy management. Taken together, these studies provide evidence for a modest positive relationship between social support and chronic illness self-management, especially for diabetes. Dietary behavior appears to be particularly susceptible to social influences. In addition, social network members have potentially important negative influences on self-management. There is a need to elucidate the underlying mechanisms by which support influences self-management and to examine whether this relationship varies by illness, type of support, and behavior. There is also a need to understand how the social environment may influence self-management in ways other than the provision of social support.
Participation in Recreational Physical Activity: Why Do Socioeconomic Groups Differ?
Authors: Burton Nicola W. , Turrell Gavin , Oldenburg Brian
Published: April 2003

This qualitative study explored how influences on recreational physical activity (RPA) were patterned by socioeconomic position. Face-to-face interviews were conducted with 10 males and 10 females in three socioeconomic groups ( N = 60). Influences salient across all groups included previous opportunities, physical health, social assistance, safety, environmental aesthetics and urban design, physical and health benefits, and barriers of self-consciousness, low skill, and weather/time of year. Influences more salient to the high socioeconomic group included social benefits, achieving a balanced lifestyle, and the barrier of an unpredictable lifestyle. Influences more salient to the high and mid socioeconomic groups included efficacy, perceived need, activity demands, affiliation, emotional benefits, and the barrier of competing demands. Influences more salient to the low socioeconomic group included poor health and barriers of inconvenient access and low personal functioning. Data suggest that efforts to increase RPA in the population should include both general and socioeconomically targeted strategies.
Do Government Subsidies To Nonprofits Crowd Out Donations or Donors?
Authors: Brooks Arthur C.
Published: April 2003

The traditional test of the public-goods crowding-out effect may mask important impacts of government subsidies on private giving because it confounds the effects of subsidies on average donation size versus their effects on the number of donors . Using panel data on the U.S. nonprofit sector, the author shows that, although increased public funding has a neutral effect on total donations, it is associated with decreased average donations but a larger pool of donors.
The Monopsony Power of the Median Voter
Authors: Goff Brian L. , Tollison Robert D.
Published: April 2003

This article attempts to establish a link between voting theory and price theory. The median voter is characterized as a monopsonist who sets a price for the winning vote in an election. As such, the median voter can extract rents from the political sector as a function of the price of substitute winning voters, which in turn will depend on the distribution of voter preferences.
Modern Data Analytic Techniques for Multisource Feedback
Authors: Yammarino Francis J.
Published: April 2003

For nearly three decades, the use of multisource ratings of organizational phenomena for developmental feedback to managers has grown. As work on multisource feedback moved from the practitioner to academic realms, scholars have sought to advance theoretical and methodological understanding of multisource ratings. The intent of this feature topic is to develop the use of rigorous analytic methods for the evaluation of the construct validity and psychometric properties of multisource ratings and feedback. In this introductory article, an overview of the four articles and techniques that comprise this feature topic are presented. Common themes and issues of the analytic methods, another technique for the analysis of multisource data, Within and Between Analysis, and directions for future research also are highlighted.
IRT-Based Assessments of Rater Effects in Multiple-Source Feedback Instruments
Authors: Barr Michael A. , Raju Nambury S.
Published: April 2003

This study compares three item response theory–based models of assessing measurement equivalence in 360° feedback: the traditional differential item functioning (DIF) methodology, Muraki’s rater’s effect model, and Patz, Junker, and Johnson’s hierarchical rater model. Using data from 491 managers collected on the Benchmarks instrument, the authors found that the traditional DIF methodology provides the most information about the rater’s conception of the ratee’s ability, whereas the other two models provide explicit estimates of rater leniency/severity. The authors also found that rater source effects of leniency and severity, even though statistically significant, did not substantially affect the observed score at the item and scale levels. The different results and conclusions produced by each model are discussed.
Exploring Differential Item Functioning in a 360-Degree Assessment: Rater Source and Method of Delivery
Authors: Penny James A.
Published: April 2003

This research used logistic regression to model item responses from a popular 360-degree assessment-for-development survey. The model used method of survey delivery and rater group to identify items exhibiting differential item functioning (DIF). The methods of survey delivery were pencil-and-paper and online by Web page. The rater groups were self, boss, peer, and direct report. The sample consisted of 374 survey families where a survey family was a set of four surveys: self, boss, peer, and direct report. Half the survey families were pencil-and-paper administration; half were online administration. The flagging procedure used effect size from Wald chi-square statistics. Results indicated little evidence that DIF existed due to method of survey delivery, lending additional support for the use of the Internet to deliver 360-degree surveys. Approximately 10% of items exhibited DIF attributable to rater group, though in every instance the magnitude of the DIF was small, suggesting that the impact of DIF on the 360-degree feedback could be slight. There was no evidence of an interaction between method of delivery and rater group. The maximum likelihood parameter estimates indicated DIF resulted from either hierarchical complexity or contingency theory. This research suggested that such forms of DIF could be naturally occurring phenomena in 360- degree assessment because both contingency and complexity can influence the perceptions by raters of a manager’s performance.
The Restriction of Variance Hypothesis and Interrater Reliability and Agreement: Are Ratings from Multiple Sources Really Dissimilar?
Authors: Lebreton James M. , Burgess Jennifer R. D. , Kaiser Robert B. , Atchley E. Kate , James Lawrence R.
Published: April 2003

The fundamental assumption underlying the use of 360-degree assessments is that ratings from different sources provide unique and meaningful information about the target manager’s performance. Extant research appears to support this assumption by demonstrating low correlations between rating sources. This article reexamines the support of this assumption, suggesting that past research has been distorted by a statistical artifact—restriction of variance in job performance. This artifact reduces the amount of between-target variance in ratings and attenuates traditional correlation-based estimates of rating similarity. Results obtained from a Monte Carlo simulation and two field studies support this restriction of variance hypothesis. Noncorrelation-based methods of assessing interrater agreement indicated that agreement between sources was about as high as agreement within sources. Thus, different sources did not appear to be furnishing substantially unique information. The authors conclude by questioning common practices in 360-degree assessments and offering suggestions for future research and application.
Interpreting the Statistical Significance of Observed AD Interrater Agreement Values: Correction to Burke and Dunlap (2002)
Authors: Smith-Crowe Kristin , Burke Michael J.
Published: April 2003

This article presents a clarification of Burke and Dunlap’s (2002) instructions for interpreting the statistical significance of observed average deviation (AD) interrater agreement values. An explanation is offered for how to use Burke and Dunlap’s critical AD values to determine statistical significance of observed AD values. In addition, Burke and Dunlap’s cutoffs for practical significance of observed AD values are discussed.
A Review and Evaluation of Exploratory Factor Analysis Practices in Organizational Research
Authors: Conway James M. , Huffcutt Allen I.
Published: April 2003

The authors surveyed exploratory factor analysis (EFA) practices in three organizational journals from 1985 to 1999 to investigate purposes for conducting EFA and to update and extend Ford, MacCallum, and Tait’s (1986) review. Ford et al. surveyed the same journals from 1975 to 1984, concluding that researchers often applied EFA poorly (e.g., relying too heavily on principal components analysis [PCA], eigenvalues greater than 1 to choose the number of factors, and orthogonal rotations). Fabrigar, Wegener, MacCallum, and Strahan (1999) reached a similar conclusion based on a much smaller sample of studies. This review of 371 studies shows reason for greater optimism. The tendency to use multiple number-of-factors criteria and oblique rotations has increased somewhat. Most important, the authors find that researchers tend to make better decisions when EFA plays a more consequential role in the research. They stress the importance of careful and thoughtful analysis, including decisions about whether and how EFA should be used.
Development of a Learning Style Orientation Measure
Authors: Towler Annette J. , Dipboye Robert L.
Published: April 2003

Trainees differ in their preferences for learning strategies, and these differences can moderate the effectiveness of training programs. Unfortunately, previous attempts to develop learning style preference measures have not yielded reliable measures. The authors conducted two studies as part of an effort to develop and provide an initial validation of a learning style orientation measure. Factor analyses revealed five distinct and reliable learning style orientations. Scores on these factors were related to personality and instructional methods preferences. Findings provided preliminary support of the convergent and discriminant validity of the measure.
Neural Networks as Statistical Tools for Business Researchers
Authors: Detienne Kristen Bell , Detienne David H. , Joshi Shirish A.
Published: April 2003

Artificial neural networks are rapidly gaining popularity in the hard sciences and in social science. This article discusses neural networks as tools business researchers can use to analyze data. After providing a brief history of neural networks, the article describes limitations of multiple regression. Then, the characteristics and organization of neural networks are presented, and the article shows why they are an attractive alternative to regression. Shortcomings and applications of neural networks are reviewed, and neural network software is discussed.
Linking Marketing and Operations
Authors: Evangelist Shane , Godwin Badger , Johnson Joey , Conzola Vincent , Kizer Robert , Young-Helou Stephanie , Metters Richard
Published: April 2003

In theory, it is a simple proposition: Make customers wait longer, and fewer of them will come back. But actual practice is complicated. Marketing develops a new product, service, affinity plan, and so on. This new marketing initiative causes changes in operational processes that increase customer service times. When waiting lines form, a small increase in service times for each customer magnifies into a significant increase in waiting time for the customer at the end of the line. The increase in waiting times causes a reduction in customer loyalty, which leads to lower customer retention, and hence, repurchases. Consequently, the marketing initiative has costs as well as benefits. Blockbuster, Inc. has developed a model that combines operational process analysis, waiting line simulation, real versus perceived waiting times, a customer loyalty model, and a financial model to find the bottom-line impact from operational changes of new marketing programs.
Does Culture Influence Web Site Quality Expectations?
Authors: Tsikriktsis Nikos
Published: April 2003

This article investigates the link between culture and Web site quality expectations. Web site quality is measured through a recently developed instrument (WEBQUAL), whereas culture is measured through Hofstede’s cultural dimensions. The analysis reveals that two cultural dimensions (masculinity and long-term orientation) are associated with higher Web site quality expectations. The findings have important managerial implications for globalization of e-services.
The Effects of Queue Structure on Attitudes
Authors: Rafaeli Anat , Barron Greg , Haber Keren
Published: April 2003

Waiting is examined here as a psychological experience, through propositions regarding the relationship between the design of a queue and the emotions and attitudes of people waiting. Propositions are tested using a paradigm that both controls features of queue structure and allows collection of real-time data from people waiting. Data collected from 134 participants confirm that people closer to a service agent are more pleased than those further away. But people waiting in a single-queue structure are shown to feel more predictability and arousal than those waiting in a multiple-queue structure. Waiting in a multiple-queue structure is, however, shown to produce a sense of lack of justice, even when no objective inequalities exist. The study suggests a useful paradigm for evaluating alternative queue structures in a laboratory setting and provides insights about psychological aspects of waiting. Both the method and the results suggest an extensive agenda for future research.
Does Customer Knowledge Affect How Loyalty is Formed?
Authors: Chiou Jyh-Shen , Droge Cornelia , Hanvanich Sangphet
Published: April 2003

The authors first propose and test a cognitive-affective-conative baseline model: Perceived service quality (both tangible company-related and employee-related factors) is modeled antecedent to satisfaction and trust, which in turn are antecedents to customer loyalty responses (word of mouth and traditional loyalty). These relationships are then hypothesized to be moderated by high versus low knowledge, a moderation based on central versus peripheral processing. The results show that employee service quality has a greater impact than company service quality on trust and on satisfaction in both knowledge groups. The relationship of trust to word of mouth is both direct and indirect through satisfaction for both knowledge groups, but the relationship of trust to loyalty is both direct and indirect through satisfaction only for the high-knowledge group; for the low-knowledge group, the relationship of trust to loyalty is indirect only, through satisfaction.
Difference Scores versus Direct Effects in Service Quality Measurement
Authors: Page Thomas J. , Spreng Richard A.
Published: April 2003

Difference scores have been widely used in many areas of marketing research. There have been numerous criticisms of difference scores, and the authors add to these criticisms by testing an implicit assumption of difference scores that has not been tested in consumer research. Specifically, difference scores assume that the components have equal and opposite effects on the dependent variable. This assumption is tested in a services setting in which difference scores are still widely used and in a laboratory experiment using a product. An alternative operationalization, the Direct Effects Model, is shown to be superior. In addition, as a result of treating the antecedents as separate predictors, it is shown that performance is the much stronger predictor of satisfaction compared to expectations. Such a finding could not be uncovered using difference scores.
Methods of Investigating Critical Incidents
Authors: Roos Inger
Published: April 2003

The methods used for analyzing customer relationships have traditionally focused exclusively on service encounters. Recently, researchers have presented these service encounters as a flow or process, although without taking time into account. Both of these perspectives on customer relationships have provided the means for developing a process-based method that does take time into account. This makes it possible to analyze and describe a customer relationship in which effects and consequences can be represented and the influenced and influencing factors prioritized. Given that the domain for analyzing the customer relationship is a switch from one service provider to another, the consequence is clear. The switch is identical to the consequence. The consequence, again, defines the criticality. Criticality and context are key concepts in the search for a deeper understanding of customer relationships, and efforts are made to include them in the development of the methods put forward in this article.
The Effect of Teams on Firm Profitability and Customer Satisfaction
Authors: Emery Charles R. , Fredendall Lawrence D.
Published: April 2003

This article examined whether the use self-directed work teams increased profit and customer satisfaction. It also examined whether leadership styles and the compensation system moderated how teams affected performance. All the firms involved in this study were automobile dealer service garages. Service garages using teams had significantly higher profits than service garages that did not use teams. The differences in customer satisfaction levels between service garages using teams and those not using teams were significant at the .10 level.
Customer Efficiency
Authors: Xue Mei , Harker Patrick T.
Published: April 2003

The continued development of e-business models has triggered a dramatic transition of customers’roles in a variety of service production and delivery processes. In the coproduction of service, the scale and scope of customers’ participation have been significantly transformed and enhanced by newe-business models and technology. This transition calls for a newunderstanding of customers’ roles in service delivery systems. The concept of customer efficiency is crucial for the successful management of systems where customers are actively engaged in service production and delivery processes. This article presents the concept of customer efficiency management (CEM), studies its relationship with other key customer characteristics, and explores its potential impact on e-business management.
The Role of Emotions in Service Encounters
Authors: Mattila Anna S. , Enz Cathy A.
Published: April 2003

This article advances our understanding of the influence of affect in consumers’ responses to brief, nonpersonal service encounters. This study contributes to the services marketing literature by examining for mundane service transactions the impact of customer-displayed emotion and affect on assessments of the service encounter and the overall experience. Observational and perceptual data from customers were matched with frontline employees in 200 transaction-specific encounters. The results of this study suggest that consumers’ evaluations of the service encounter correlate highly with their displayed emotions during the interaction and postencounter mood states. Finally, the findings indicate that frontline employees’perceptions of the encounter are not aligned with those of their customers. The managerial implications of these findings are briefly discussed.
Service Locus of Control
Authors: Bradley Graham L. , Sparks Beverley A.
Published: April 2003

This article reports on the conceptualization of the construct of service locus of control, a dispositional variable with implications for consumer behavior in a range of service settings. The development of a self-administered scale to measure this construct is described. In its final form, the 14-item measure contains three subscales—Internal, Powerful Others, and Luck—which are shown through exploratory and confirmatory factor analyses to be robust and relatively independent of each other. Three studies are reported that provide evidence of the scale’s reliability and validity. Further tests of, and applications for, the instrument are discussed.
Customer Equity Management
Authors: Hogan John E. , Lemon Katherine N. , Rust Roland T.
Published: April 2003

The authors present an overview of a new approach to marketing—one that seeks to maximize customer equity by managing the customer asset. Using a resource-based view, the article provides a framework for approaching marketing through the lens of the customer asset. The authors propose that the ability to acquire, manage, and model customer information is a key asset of the firm that can be a source of sustained advantage. Challenges to the implementation of this approach and the changes that the approach necessitates in marketing strategy are discussed. The authors propose several areas for future research in the area of customer equity and management of the customer asset.
Linking Customer Assets to Financial Performance
Authors: Hogan John E. , Lehmann Donald R. , Merino Maria , Srivastava Rajendra K. , Thomas Jacquelyn S. , Verhoef Peter C.
Published: April 2003

As more firms adopt a customer asset management approach to their business, it has become increasingly important to understand how customer management efforts relate to the financial performance of the firm. Of specific interest to shareholders is the relationship between traditional financial measures and customer-centric measures. The customer-centric measure that has received the most attention is customer lifetime value (CLV). In this article, the authors argue that the basic CLV model represents a useful foundation from which to begin to fill the gap between marketing actions and shareholder value. However, much work remains to be done before appropriate models can be developed that reflect the true value of a customer to the firm. Specifically, this article elaborates on how factors such as risk associated with customer behavior dynamics, social and competitive effects, and the effect of the product life cycle can be incorporated into the basic CLV model.
Marketing Actions and the Value of Customer Assets
Authors: Berger Paul D. , Bolton Ruth N. , Bowman Douglas , Briggs Elten , Kumar V. , Parasuraman A. , Terry Creed
Published: April 2003

This article develops a framework for assessing how marketing actions affect customers’lifetime value to the firm. The framework is organized around four critical actions that firms must take to effectively manage the asset value of the customer base: database creation, market segmentation, forecasting customer purchase behavior, and resource allocation. In this framework, customer lifetime value is treated as a dynamic construct, that is, it influences the eventual allocation of marketing resources but is also influenced by that allocation. By viewing customers as assets and systematically managing these assets, a firm can identify the most appropriate marketing actions to acquire, maintain, and enhance customer assets and thereby maximize financial returns. The article discusses in detail how to assess customer lifetime value and manage customers as assets. Then, it identifies key research challenges in studying customer asset management and the managerial challenges associated with implementing effective customer asset management practices.
Toward an Individual Customer Profitability Model
Authors: Libai Barak , Narayandas Das , Humby Clive
Published: April 2003

Although most published customer lifetime value models focus on strategic-level marketing decisions, managers also need models that enable them to make resource allocation decisions for individual customers. A common misperception among scholars and managers is that it is necessary to use individual-level customer profitability models to make such decisions. This article argues that a segment-based approach to customer profitability analysis can be a reasonable alternative to an individual model. The proposed stochastic segment-based approach retains the actionable information associated with individual-level analysis while also maintaining the simplicity of the more aggregate-level models. In this article, the authors develop such a segment-based assessment of customer profitability and then briefly describe an example of a major European retailer that successfully uses the approach to manage its customer base. Directions for future research in the area of stochastic customer equity modeling are also discussed.
Seven Barriers to Customer Equity Management
Authors: Bell David , Deighton John , Reinartz Werner J. , Rust Roland T. , Swartz Gordon
Published: April 2003

The article reviews the evolution from brand-centered marketing to customer-centered marketing and the beginnings of a focus on viewing the customer as an asset. It illustrates the practice by describing the use of a loyalty program to identify and respond to high-potential customers in the market for business-class hotels. Next, it considers seven challenges that impede wider adoption of customer equity management and concludes with a schematic model of customer-centered marketing management.
“The Worms Are Weak”
Authors: Inhorn Marcia C.
Published: April 2003

Male infertility is a major global reproductive health problem, contributing to more than half of all cases of infertility worldwide. Yet women typically bear the social burden of childlessness when their husbands are infertile. This article explores the four major patriarchal paradoxes surrounding male infertility in the Muslim Middle Eastern country of Egypt. There, women in childless marriages typically experience procreative blame, even when male infertility (glossed as “weak worms”) is socially acknowledged. In addition, Egyptian women married to infertile men experience diminished gender identity and threats of male-initiated divorce. Ironically, the introduction of new reproductive technologies to overcome male infertility has only served to increase this divorce potential. Although male infertility also presents a crisis of masculinity for Egyptian men, this crisis often redounds in multiple ways on the lives of women, who ultimately pay the price for male infertility under conditions of Middle Eastern patriarchy.
Mullahs, Martyrs, and Men
Authors: Gerami Shahin
Published: April 2003

A core component of the Islamic Revolution’s ideology was reformulation of gender discourse wrapped around an Islamic hypermasculinity. Attention has been focused on women’s roles and rights in the Islamic Republic, and men are assumed to universally have benefited from the regime’s policies. This hypermasculinity of the Republic has revised prerevolutionary ideals promoting new ideals of manhood. Mullahs are the sage interpreters of the Qur’an and Shari‘at. The young men who bide the dictates of the mullahs and sacrifice themselves for the Republic are martyrs. Then there are the ordinary men. The Shari‘at favors them at the family and civil society, but such a blanket vision ignores the costs paid by all men depending on their social class. High unemployment, inflation, oppression, and rampant drug abuse assail all men. They all pay for gender discrimination against all women in general and women of their social group in particular.
Gender (and) Imperialism
Authors: Hassan Waïl S.
Published: April 2003

The seamless continuity between colonialism, racism, and patriarchy makes it imperative for postcolonial criticism to question the foundational category of gender. As Judith Butler argues, gender postulates a normative masculinity poised against a femininity construed as lack or deviation. This normative masculinity asserts itself in colonial discourse, which, as Edward Said observes, represents a masculine Europe dominating a feminized Orient. At the same time, racial discourse represents African men as hypermasculine, as Frantz Fanon and Cornel West, among others, have observed. Thus, the African man occupies at once masculine and feminine subject positions and, likewise, the European women figures ambivalently as both masculine and feminine. Tayeb Salih’s Season of Migration to the North depicts such ambivalent spaces that enable a critique of colonial and patriarchal notions of gender.
Angry Aggression Among Police Officers
Authors: Griffin Sean P. , Bernard Thomas J.
Published: April 2003

This article uses angry aggression theory to explain police use of extralegal force. As applied to police behavior, angry aggression theory argues that the chronic stress of police work along with the inability to respond to the actual sources of that stress increase both the perception of threats and the aggressiveness of responses to perceived threats. In addition, social isolation of police officers increases their tendency to displace aggression onto visible and vulnerable targets in the immediate environment. The theory does not assert that these tendencies are necessarily actualized. Indeed, cognitive structuring techniques and stress-reduction policies can prevent such actualization.
A Comparison Of Police Field Training Officers’ And Nontraining Officers’ Conflict Resolution Styles: Controlling Versus Supportive Strategies
Authors: Sun Ivan Y.
Published: April 2003

This article examines the behavioral differences between police field-training officers (FTOs) and their comparable colleagues in handling interpersonal conflicts. Data used were collected from two metropolitan police departments. Actions taken by officers are grouped into two major categories, control and supportive, and are then examined along two dimensions, diversity and aggressiveness. Findings show that FTOs perform a greater number of supportive actions than do non-FTOs throughout their encounters with citizens. FTOs and non-FTOs, however, display no differences in the level of force involved in their control actions toward citizens. Implications for policy and future research are provided.
Police Use Of Force And Suspect Resistance: The Micro Process Of The Police-Suspect Encounter
Authors: Terrill William
Published: April 2003

Using data collected as part of an observational study of the police in Indianapolis, Indiana, and St. Petersburg, Florida, this research examines 3,544 police-suspect encounters in an attempt to better understand the application of nonlethal force and the relationship between officer use of force and suspect resistance. More specifically, it examines the extent of and variation in force and resistance and the interplay between the two. Results show that when both verbal and physical forms of coercion are considered, force occurs quite frequently—in more than half of all encounters. Conversely, suspects displayed some form of resistance in 12% of all encounters. When multiple uses of force and resistance within individual encounters are considered, the frequency of both behaviors increases substantially. In addition, a majority of both forceful and resistant behaviors fall on the lower end of continuum (e.g., verbal commands as opposed to striking with a baton). Encounters that began with some form of force resulted in a greater frequency of subsequent suspect resistance and an increased use of additional force at some later point in the encounters—calling into question the utility of a “take charge” approach to maintaining control within police-suspect encounters.
Saying One Thing, Meaning Another: The Role Of Parables In Police Training
Authors: Ford Robert E.
Published: April 2003

Research suggests that police recruits come to policing with high ideals and positive ethical standards. Yet as early as the police academy, subtle shifts in recruit attitudes and values occur. By the end of the rookie year, this ethical value shift is almost complete, and it has negative ethical implications. This ethical value shift places many officers in conflict with a number of legal standards and core societal values. Although research has identified these outcomes, there is only limited understanding of the processes that fuel these ethical value shifts. This article presents exploratory research in police socialization processes and identifies process mechanisms that trigger a number of these value shifts. Structural elements in policing training that sustain these mechanisms are analyzed.
The Fracture Behavior of Aluminum Foam Sandwich Structures Based on Fiber Reinforced Thermoplastics
Authors: Kiratisaevee H. , Cantwell W. J.
Published: April 2003

The fracture properties of a range of novel sandwich structures based on an aluminum foam core and fiber reinforced thermoplastic skins have been investigated. Initially, the mixed-mode interlaminar fracture properties of the thermoplastic-matrix composites were investigated using the mixed-mode flexure test geometry. Here, values of GI/IIc ranged from 2400 J/m2 for the glass fiber/nylon composite to 3300 J/m2 for a glass fiber/polypropylene composite. The fracture properties of the thermoplastic interlayer materials used to bond the skin and core materials were also investigated and found to vary between approximately 1200 J/m2 for a PP-based system to 6800 J/m2 for a neat PEEK interlayer.

Tests using the single cantilever beam sandwich (SCB) specimen showed that the degree of adhesion between the composite skins and the foam core was good at both quasi-static and dynamic rates of loading. An optical examination of the PP and PEEK-based SCB samples indicated that the primary crack propagated through the core material whereas failure in the nylon-based system occurred through the interlayer material at the skin-core interface. The fracture energies associated with both types of failure were found to be significantly lower than those of the plain composite and modified samples containing the thermoplastic interlayer.

The impact response of three types of sandwich structure was investigated by conducting low velocity impact tests on simply supported beams. Here, damage in the form of fiber fracture and splitting in the composite skins and localized crushing in the composite core were observed at intermediate and high incident energies. Flexure tests to characterize the residual load-bearing properties of the sandwich structures highlighted the superior mechanical properties of the carbon fiber/PEEK-based system.
Influences of Foam Density and Core Thickness on Debond Toughness of Sandwich Specimens with PVC Foam Core
Authors: Viana G. M. , Carlsson L. A.
Published: April 2003

Face/core debond toughness, expressed as the critical strain energy release rate (Gc), was determined for sandwich specimens with composite and aluminum face sheets over various cross-linked PVC foam cores. Crack propagation occurred in the core, near the face/core interface for specimens with adequate face/core adhesion. Only for the highest density foam it was possible to propagate the crack in the immediate vicinity of the actual core/resin interface. The face/core debond toughness increased with increased foam density and reduced core thickness. For thick cores, the face/core toughness was independent of the core thickness.
The Static Mechanical Performance of Repaired Composite Sandwich Beams: Part I - Experimental Characterisation
Authors: Mahdi S. , Kinloch A. J. , Matthews F. L. , Crisfield M. A.
Published: April 2003

The behaviour of undamaged and repaired CFRP sandwich beams loaded in four-point bending is described. Three repair configurations (one overlap and two scarf) were tested in tension and compression, and two repair systems (based upon either a relatively high- and or low-temperature cure) were employed. It was found that the repair schemes tested recovered a very high fraction of the undamaged strength, although the ranking order of the configurations depended on the loading mode (i.e., tension or compression). The choice of the repair system did not have a major effect on the strength of the repaired CFRP beams.
Equipment for Impact Testing of Sandwich Panels
Authors: Kepler J.
Published: April 2003

This article describes test equipment for testing localized, penetrating impact on sandwich panels. The sandwich panels in question are 500 500 mm2 with a typical thickness of 40-55 mm. The impact velocities are in the region 50-130 m/s, with an impactor mass between 0.5 and 1 kg, and an impactor diameter of 50 mm. The above parameters correspond to localized impact on train fronts, airplanes at take-off and landing, cars and similar. A series of 7 impact tests on identical sandwich panels at varying velocities is described.
Numerical and Experimental Analysis of the Influence of Edge Conditions on the Deflection of a Clamped-Clamped Asymmetric Sandwich Strip
Authors: Karczmarzyk S. , Meyer-Piening H. -R. , Caviezel M.
Published: April 2003

Influence of different edge boundary conditions for the core and for the faces on deflections of the asymmetric sandwich strip and beam, with ends enabling carrying the bending moment are investigated in the paper. Two kinds of asymmetry of the clamped-clamped (C-C) sandwich structure are taken into account namely, asymmetry of faces and asymmetry of fastening of the faces to edge inserts. Numerical results which are presented to demonstrate the influence of the core conditions have been obtained according to a new analytical 2D model and by FEM. In order to make the analysis more valuable some experimental results have been compared. Influence of different edge conditions for the core, edge in-plane displacements of faces as well as asymmetry of faces and their fastening to inserts on the strip and beam deflection is examined. The usefulness of the new 2D model for validation of the FEM models is shown. All considerations and results refer to the sandwich structures composed of isotropic layers.
Physiologic Factors Contributing to a Transition in Oral Immunity among Mechanically Ventilated Adults
Authors: O’Neal Pamela V. , Brown Nicole , Munro Cindy
Published: April 2003

Ventilator-associated pneumonia (VAP), a specific type of nosocomial pneumonia, occurs in approximately 21% of patients in intensive care, and the mortality can be as high as 71%. VAP causes considerable mortality and morbidity, and it exponentially increases health care costs. The incidence of VAP is associated with oropharyngeal colonization of gram-negative bacteria. Within 48 h of hospital admission, the composition of the oropharyngeal flora of critically ill patients undergoes a change fromthe usual gram-positive streptococci and dental pathogens to a predominant gram-negative flora that includes more virulent organisms, which predispose patients to VAP. Identification and understanding of this oral transition from gram-positive to predominantly gram-negative flora may assist health care professionals in differentiating among oral immune markers that suggest compromised immunity. The purpose of this article is to provide a review of the literature that promotes an understanding of current knowledge about the transition of oral immunity in mechanically ventilated patients.
Preterm Infant Temperature Circadian Rhythm: Possible Effect of Parental Cosleeping
Authors: Thomas Karen A. , Burr Robert
Published: April 2003

The purpose of this study was to describe the circadian rhythm of abdominal skin temperature and explore factors related to the timing of circadian rhythmacr ophase. Thirty-four preterminfants (gestational age 26 to 33 weeks) were studied in the home environment at 44 to 46 weeks postconceptional age. Insulated abdominal skin was monitored continuously, and parents recorded sleep/wake activity over a 24-h period. Circadian rhythmwas analyzed using cosinor analysis. Using MANCOVA, the effects of cosleeping, feeding method, night feeding, hospital stay, time home, and illness on acrophase were determined. Infants demonstrated evidence of developing circadian rhythmof temperature. Cosleeping and length of hospital stay were significantly related to acrophase. The mean acrophase for cosleeping infants was 07:44 (95% confidence interval = 05:12, 11:08), whereas that for non-cosleeping infants was 22.05 (95% confidence interval = 17:31, 01:42). Proximity with parents during nighttime hours may serve to entrain preterminfant circadian rhythm.
Role of Nitric Oxide in Wound Healing
Authors: Childress Beverly B. , Stechmiller Joyce K.
Published: April 2003

Chronic wounds mainly affect elderly individuals and persons with comorbid diseases due to a compromised immune status. An age-related decline in immune function deters proper healing of wounds in an orderly and timely manner. Thus, older adults with 1 or more concomitant illnesses are more likely to experience and suffer from a nonhealing wound, which may drastically decrease their quality of life and financial resources. Novel therapies in wound care management rely heavily on our current knowledge of wound healing physiology. It is well established that normal wound healing occurs sequentially and is strictly regulated by pro-inflammatory cytokines and growth factors. A multitude of commercial products such as growth factors are available; however, their effectiveness in healing chronic wounds has yet to be proven. Recently, investigators have implicated nitric oxide (NO) in the exertion of regulatory forces on various cellular activities of the inflammatory and proliferative phases of wound healing. Gene therapy in animal studies has shown promising results and is furthering our understanding of impaired wound healing. The purpose of this article is to review the literature on NO and its role in wound healing. A discussion of the physiology of normal healing and the pathophysiology of chronic wounds is provided.
Impaired Vasodilation and Nitric Oxide Synthase Activity in Glucocorticoid-Induced Hypertension
Authors: Mitchell Brett M. , Webb R. Clinton
Published: April 2003

Synthetic glucocorticoids are among the most widely prescribed medications by physicians. Although they have a vast array of beneficial effects such as immunosuppression and anti-inflammation, excess glucocorticoids can lead to iatrogenic Cushing’s syndrome, which includes hypertension and cardiovascular disease. The exact mechanism by which glucocorticoids elevate blood pressure is not completely understood, but it appears to be a complex pathology that involves increased responsiveness to vasoconstrictors and decreased vasodilator production. Nitric oxide is a vasodilator that plays a key role in blood pressure regulation, and previous studies have shown that a reduction in nitric oxide production or bioavailability contributes to hypertension. Tetrahydrobiopterin, a necessary cofactor for nitric oxide synthase activity, can affect nitric oxide production and bioavailability, with low levels causing decreased nitric oxide production. However, little is known about the interaction between glucocorticoids and tetrahydrobiopterin levels. In this review, the roles of nitric oxide and tetrahydrobiopterin in the pathogenesis of glucocorticoid hypertension will be discussed. Furthermore, the authors propose that glucocorticoids exert a genomic effect to decrease guanosine triphosphate cyclohydrolase I, the rate-limiting enzyme in the production of tetrahydrobiopterin. In the future, tetrahydrobiopterin supplementation in patients with iatrogenic Cushing’s syndrome may prove to be beneficial and decrease mortality attributed to cardiovascular disease.
Presence and Predictors of Hepatitis C Virus RNA in the Semen of Homeless Men
Authors: Nyamathi Adeline , Robbins Wendie A. , Fahey John L. , Wiley Dorothy , Pekler Vyacheslav A. , Longshore Douglas , Robins Terry A. , Singh Jan , Saab Sammy
Published: April 2003

Although the possibility of sexual transmission of the hepatitis C virus (HCV) remains controversial, little is known of the associations of positive semen specimens with potential demographic and behavioral risk factors. Knowledge of these predictors may suggest factors that increase risk of HCV RNA in the semen. Semen and blood from 80 HCV-infected homeless men were evaluated for the presence ofHCVRNA by means of branch DNA and transcription-mediated amplification analyses. Associations of selected demographic and behavioral characteristics of the participants with presence or absence of HCV in their semen were also assessed. HCV RNA was detected in the semen of 36% of the sample. Associations were found with HCV RNA in semen and older age, higher viral loads of HCV in blood, current alcohol and lifetime methamphetamine use, and having been vaccinated for the hepatitis B virus. Findings suggest that sexual transmission of HCV is plausible and shed light on the need to conduct more in-depth investigations.
Natural Killer Cell Function and Psychological Distress in Women with and without Irritable Bowel Syndrome
Authors: Motzer Sandra Adams , Jarrett Monica , Heitkemper Margaret M. , Tsuji Joyce
Published: April 2003

The primary purpose of this exploratory study was to compare percentages of natural killer (NK) cells and activated NK and T cells, and both cytotoxic and in vitro cytokine production activity in women with and without symptomatic irritable bowel syndrome (IBS). A secondary purpose was to examine the relationships of psychological distress and low sense of coherence with immune function indicators and stress hormones. NK cell percentage and activity have been shown to vary in response to many psychological and physiological stressors. The authors compared 2 groups of women: symptomatic IBS (n = 12) and control (n = 12). Between-subject variability for all immune measures was large. The percentage of activated NK and T cells was significantly lower in the IBS group compared to control (Mann-Whitney U = 30, P = 0.05). Relationships were significant between activated NK and T cell percentage and depression, anxiety, and overall distress (r = –0.54, –0.49, and –0.47, respectively, P < 0.03) and between interferon-gamma production and anxiety (r = –0.45, P < 0.03). There was a trend toward a positive relationship between sense of coherence and NK cytotoxicity (r = 0.39, P = 0.11). These findings are important because they suggest that nursing interventions targeting ongoing physical and psychological distress might also be helpful in improving immune function.
The Case for an Immunologic Cause of Obesity
Authors: Rogge Mary Madeline
Published: April 2003

The most pressing public health problem at the start of the century is the mounting prevalence of obesity. Acknowledging an interplay between genetics and the environment in the development of obesity, most experts still attribute the rising trend toward obesity to the ready availability of food and an increasingly sedentary lifestyle. With a growing body of evidence demonstrating strong links between adipose tissue and the immune system, there is good reason to ask whether the cause of the current obesity epidemic might be a less obvious disorder of immune function, perhaps even the consequence of infection. The interplay between preadipocytes and adipocytes and the immune system is examined, and recommendations for further research are offered.