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Modeling Analyses (modeling + analysis)
Kinds of Modeling Analyses Selected AbstractsUsing the job demands-resources model to predict burnout and performanceHUMAN RESOURCE MANAGEMENT, Issue 1 2004Arnold B. Bakker The job demands-resources (JD-R) model was used to examine the relationship between job characteristics, burnout, and (other-ratings of) performance (N = 146). We hypothesized that job demands (e.g., work pressure and emotional demands) would be the most important antecedents of the exhaustion component of burnout, which, in turn, would predict in-role performance (hypothesis 1). In contrast, job resources (e.g., autonomy and social support) were hypothesized to be the most important predictors of extra-role performance, through their relationship with the disengagement component of burnout (hypothesis 2). In addition, we predicted that job resources would buffer the relationship between job demands and exhaustion (hypothesis 3), and that exhaustion would be positively related to disengagement (hypothesis 4). The results of structural equation modeling analyses provided strong support for hypotheses 1, 2, and 4, but rejected hypothesis 3. These findings support the JD-R model's claim that job demands and job resources initiate two psychological processes, which eventually affect organizational outcomes. © 2004 Wiley Periodicals, Inc. [source] Communicative Correlates of Satisfaction, Family Identity, and Group Salience in Multiracial/Ethnic FamiliesJOURNAL OF MARRIAGE AND FAMILY, Issue 4 2009Jordan Soliz Guided by the Common Ingroup Identity Model (S. L. Gaertner & J. F. Dovidio, 2000) and Communication Accommodation Theory (C. Shepard, H. Giles, & B. A. LePoire, 2001), we examined the role of identity accommodation, supportive communication, and self-disclosure in predicting relational satisfaction, shared family identity, and group salience in multiracial/ethnic families. Additionally, we analyzed the association between group salience and relational outcomes as well as the moderating roles of multiracial/ethnic identity and marital status. Individuals who have parents from different racial/ethnic groups were invited to complete questionnaires on their family experiences. Participants (N = 139) answered questions about relationships with mothers, fathers, and grandparents. The results of the multilevel modeling analyses are discussed in terms of implications for understanding multiracial/ethnic families and family functioning. [source] How changes in job demands and resources predict burnout, work engagement, and sickness absenteeismJOURNAL OF ORGANIZATIONAL BEHAVIOR, Issue 7 2009Wilmar B. Schaufeli The present longitudinal survey among 201 telecom managers supports the Job Demands-Resources (JD-R) model that postulates a health impairment process and a motivational process. As hypothesized, results of structural equation modeling analyses revealed that: (1) increases in job demands (i.e., overload, emotional demands, and work-home interference) and decreases in job resources (i.e., social support, autonomy, opportunities to learn, and feedback) predict burnout, (2) increases in job resources predict work engagement, and (3) burnout (positively) and engagement (negatively) predict registered sickness duration ("involuntary" absence) and frequency ("involuntary" absence), respectively. Finally, consistent with predictions results suggest a positive gain spiral: initial work engagement predicts an increase in job resources, which, in its turn, further increases work engagement. Copyright © 2009 John Wiley & Sons, Ltd. [source] Relationships between psychological climate perceptions and work outcomes: a meta-analytic reviewJOURNAL OF ORGANIZATIONAL BEHAVIOR, Issue 4 2003Christopher P. Parker In this study, meta-analytic procedures were used to examine the relationships between individual-level (psychological) climate perceptions and work outcomes such as employee attitudes, psychological well-being, motivation, and performance. Our review of the literature generated 121 independent samples in which climate perceptions were measured and analyzed at the individual level. These studies document considerable confusion regarding the constructs of psychological climate, organizational climate, and organizational culture and reveal a need for researchers to use terminology that is consistent with their level of measurement, theory, and analysis. Our meta-analytic findings indicate that psychological climate, operationalized as individuals' perceptions of their work environment, does have significant relationships with individuals' work attitudes, motivation, and performance. Structural equation modeling analyses of the meta-analytic correlation matrix indicated that the relationships of psychological climate with employee motivation and performance are fully mediated by employees' work attitudes. We also found that the James and James (1989) PCg model could be extended to predict the impact of work environment perceptions on employee attitudes, motivation, and performance. Despite the number of published individual-level climate studies that we found, there is a need for more research using standardized measures so as to enable analyses of the organizational and contextual factors that might moderate the effects of psychological climate perceptions. Finally, we argue for a molar theory of psychological climate that is rooted in the psychological processes by which individuals make meaning or their work experiences. Copyright © 2003 John Wiley & Sons, Ltd. [source] Longitudinal Trajectories of Ethnic Identity During the College YearsJOURNAL OF RESEARCH ON ADOLESCENCE, Issue 4 2009Moin Syed The goals of this study were to examine trajectories of change in ethnic identity during the college years and to explore group-level and individual-level variations. Participants were 175 diverse college students who completed indices of ethnic identity exploration and commitment, self-esteem, and domain-general identity resolution. Multilevel modeling analyses indicated that exploration and commitment continued to increase during the college years. Although there were ethnic differences in initial levels of ethnic identity, the rate of change did not vary by ethnicity. Domain-general identity was positively associated with exploration and commitment and mediated the association between self-esteem and commitment. The findings highlight the ongoing development of ethnic identity beyond adolescence and suggest that ethnic identity is part of the larger identity project. [source] Acculturation and Enculturation Trajectories Among Mexican-American Adolescent OffendersJOURNAL OF RESEARCH ON ADOLESCENCE, Issue 4 2009George P. Knight This study examines changes over time in ethnic affirmation/belonging and ethnic identity achievement, Spanish language use, English language use, Mexican/Mexican-American affiliation/identification and Anglo affiliation/identification in a sample of Mexican-American adolescents participating in a longitudinal study of juvenile offenders. The Multigroup Ethnic Identity Measure and the Acculturation Rating Scale for Mexican Americans-II were completed by the Mexican-American adolescents 7 times over a 3-year period. The findings from longitudinal growth modeling analyses and growth mixture modeling analyses indicate that there is heterogeneity in the initial scores and changes over time on these variables that are related to markers for the cultural qualities of the home environment (i.e., generational status and mother's most frequent language use). In contrast to expectations, marginalized or assimilated acculturation trajectories/types were not overrepresented in this sample of adolescent offenders. Implications for our understanding of the nature of acculturation and enculturation processes and the way these processes are studied are discussed. [source] Linking Changes in Parenting to Parent,Child Relationship Quality and Youth Self-Control: The Strong African American Families ProgramJOURNAL OF RESEARCH ON ADOLESCENCE, Issue 1 2005Gene H. Brody A randomized prevention trial was conducted contrasting families who took part in the Strong African American Families Program (SAAF), a preventive intervention for rural African American mothers and their 11-year-olds, with control families. SAAF is based on a conceptual model positing that changes in intervention-targeted parenting behaviors would enhance responsive-supportive parent,child relationships and youths' self-control, which protect rural African American youths from substance use and early sexual activity. Parenting variables included involvement-vigilance, racial socialization, communication about sex, and clear expectations for alcohol use. Structural equation modeling analyses indicated that intervention-induced changes in parenting were linked with changes in responsive,supportive parent,child relationships and youth self-control. [source] Linking impulsivity to dysfunctional thought control and insomnia: a structural equation modelJOURNAL OF SLEEP RESEARCH, Issue 1-Part-I 2010RALPH E. SCHMIDT Summary According to cognitive models of insomnia, excessive mental activity at bedtime may be viewed as an important impediment to the process of falling asleep. A further assumption of these models is that ,cognitive arousal' may be perpetuated and exacerbated by counterproductive strategies of thought management. As yet, little is known about factors that may predispose people to rely on these strategies when confronted with thoughts that keep them awake at night. This study examined the relations between impulsivity, use of different thought-control strategies and insomnia severity. A sample of 391 university students completed the UPPS Impulsive Behavior Scale, the Thought Control Questionnaire Insomnia-Revised and the Insomnia Severity Index. Correlation analyses revealed that two facets of impulsivity (urgency and lack of perseverance), two strategies of thought control (aggressive suppression and worry) and insomnia severity were positively associated. Follow-up structural equation modeling analyses showed that the two mentioned thought-control strategies mediated the effects of the two facets of impulsivity on sleep problems. These findings extend existing cognitive accounts of insomnia by suggesting how predisposing and perpetuating factors may be related: specific personality traits may incline individuals to respond with dysfunctional thought-control strategies to unwanted mental activity at night. [source] Longitudinal linkages between perceived social support and posttraumatic stress symptoms: Sequential roles of social causation and social selectionJOURNAL OF TRAUMATIC STRESS, Issue 3 2008Krzysztof Kaniasty The authors examined social causation and social selection explanations for the association between perceptions of social support and psychological distress. Data came from a sample of 557 victims of natural disaster in Mexico. Structural equation modeling analyses indicated that social causation (more social support leading to less posttraumatic stress disorder [PTSD]) explained the support-to-distress relationship in the earlier postdisaster phase, 6 to 12 months after the impact. Both causal mechanisms emerged as significant paths in the midpoint of the study (12 and 18 months). Only social selection (more PTSD leading to less social support) accounted for the support-to-distress relationship at 18 to 24 months after the event. Interpersonal and social dynamics of disasters may explain why these two contrasting causal mechanisms emerged over time. [source] Resiliency among individuals with childhood sexual abuse and HIV: Perspectives on addressing sexual traumaJOURNAL OF TRAUMATIC STRESS, Issue 4 2006Nalini Tarakeshwar This study examined how resiliency (represented by optimism, social support, religiosity, and finding growth and meaning), within the context of perceived impact of sexual trauma and HIV-related stress, was linked to perspectives on addressing trauma among individuals (N = 266) with HIV and childhood sexual abuse (CSA). Structural equation modeling analyses indicated that lower resiliency and greater HIV-related stress were related to negative feelings about addressing trauma, whereas greater resiliency and higher perceived impact of sexual trauma were associated with positive feelings about addressing trauma. Findings suggest that multiple factors influence perspectives on addressing trauma among individuals with HIV and CSA, and that resiliency might influence these attitudes. [source] Empathic accuracy and accommodative behavior among newly married couplesPERSONAL RELATIONSHIPS, Issue 4 2002Shelley Dean Kilpatrick An established method for assessing empathic accuracy was used to examine the consequences of accurate understanding during the early years of marriage. Structural equation modeling analyses simultaneously examined within,individual and across,partner associations among variables (actor effects and partner effects). During the first year of marriage, actor effects and partner effects were observed for two presumed consequences of empathic accuracy,accommodative behavior and couple well,being. Actor effects, partner effects, or both were observed for three possible determinants of empathic accuracy,commitment level, partner perspective,taking, and psychological femininity. Levels of empathic accuracy reliably declined following the first year of marriage, as did the strength of the above,noted associations with empathic accuracy. [source] Beyond Preadoptive Risk: The Impact of Adoptive Family Environment on Adopted Youth's Psychosocial AdjustmentAMERICAN JOURNAL OF ORTHOPSYCHIATRY, Issue 3 2010Juye Ji Adopted children often are exposed to preadoptive stressors,such as prenatal substance exposure, child maltreatment, and out-of-home placements,that increase their risks for psychosocial maladjustment. Psychosocial adjustment of adopted children emerges as the product of pre- and postadoptive factors. This study builds on previous research, which fails to simultaneously assess the influences of pre- and postadoptive factors, by examining the impact of adoptive family sense of coherence on adoptee's psychosocial adjustment beyond the effects of preadoptive risks. Using a sample of adoptive families (n = 385) taking part in the California Long Range Adoption Study, structural equation modeling analyses were performed. Results indicate a significant impact of family sense of coherence on adoptees' psychosocial adjustment and a considerably less significant role of preadoptive risks. The findings suggest the importance of assessing adoptive family's ability to respond to stress and of helping families to build and maintain their capacity to cope with stress despite the sometimes fractious pressures of adoption. [source] Hypersensitivity to Social Rejection and Perceived Stress as Mediators between Attachment Anxiety and Future Burnout: A Prospective AnalysisAPPLIED PSYCHOLOGY, Issue 3 2010Sigalit Ronen Drawing on Sociometer Theory, the current study examined whether the tendency to focus on and worry about social rejection at the workplace can predict stress and burnout. Data were collected at two time points from 231 hotel employees. Prospective-longitudinal design, structural equation modeling analyses revealed that participants' hypersensitivity to social rejection at the workplace predicted an increase in stress and in burnout across the 1 month of participation. Furthermore, the findings revealed that hypersensitivity to social rejection fully mediated the link between attachment anxiety and future stress and that hypersensitivity to social rejection and stress fully mediated the link between attachment anxiety and future burnout. Approximately 64 per cent of the variance in future burnout was explained by these variables. The results demonstrate the significant role social evaluative stressors play in the development of stress responses at the workplace. S'appuyant sur la sociometer theory, la présente étude examine si la tendance à se préoccuper et s'inquiéter du rejet social sur le lieu de travail peut prédire le stress et l'épuisement. Les données ont été collectées par deux fois auprès de 231 employés d'hôtellerie. Le traitement des études longitudinales par des analyses de modélisation par équations structurelles révèle que l'hypersensibilité des sujets au rejet sur le lieu de travail contribue à une augmentation du stress et de l'épuisement au cours du mois de participation. Les conclusions soulignent que l'hypersensibilité au rejet social est totalement influencée par le lien entre anxiété, attachement et stress futur et que l'hypersensibilité au rejet social et au stress est totalement influencée par le lien entre anxiété, attachement et épuisement à venir. Approximativement 64% de la variance de l'épuisement à venir est expliqué par ces variables. Les résultats montrent le rôle significatif joué par des sources de stress liées au jugement social d'autrui dans le développement des réponses de stress sur le lieu de travail. [source] HRM Practices and Organizational Commitment: Test of a Mediation ModelCANADIAN JOURNAL OF ADMINISTRATIVE SCIENCES, Issue 4 2000John P. Meyer This study was conducted to examine the mechanisms involved in observed relations between human resource management (HRM) practices and employee commitment. Employees (N = 281) from several organizations completed a survey that included measures of (a) the quality of HRM practices pertaining to performance appraisal, benefits, training, and career development used in their organizations, (b) procedural justice and organizational support, and (c) affective, continuance, and normative commitment to the organization. Structural equation modeling analyses revealed that relations between employees' evaluations of HRM practices and their affective and normative commitment were largely mediated by perceptions of organizational support and procedural justice. These findings support previous claims that, although HRM practices can be valuable tools in the establishment and maintenance of employee commitment, their effects are neither direct nor unconditional. Résumé Cette étude avait pour but d'examiner certains mécan-ismes intervenant dans le lien entre les pratiques de ges-tion des ressources humaines et l'engagement des employés. Des employés (N=281) de plusieurs organisations ont rempli un questionnaire incluant des mesures de: (a) qualité des pratiques de gestion des ressources humaines en matière d'évaluation du rendement, de compensation, deformation et de développement profes-sionnel, (b) justice en matiere de procedure et soutien organisationnel, et (c) engagement organisationnel affectif, continuation, et normatif. Des analyses basées sur la modélisation d'équations structurelles ont révélé que les liens entre l'évaluation par les employés des pratiques de gestion des ressources humaines et leur engagement affectif et normatif étaient en grande partie médiatisés par leur perception du soutien organisationnel et de justice en matière de procedure. Ces résultats corroborent le fait que malgré l'importance des pratiques de gestion des ressources humaines dans l'étab-lissement et le maintien de l'engagement des employés, leurs effets ne sont ni directs ni inconditionnels. [source] Race and Gender Influences on Adjustment in Early Adolescence: Investigation of an Integrative ModelCHILD DEVELOPMENT, Issue 5 2002David L. DuBois This research investigated an integrative model of race, and gender,related influences on adjustment during early adolescence using a sample of 350 Black and White youth. In the proposed model, prejudice/discrimination events, as well as race and gender daily hassles, contribute to a general stress context. The stress context, in turn, influences levels of emotional and behavioral problems in adjustment, with these associations mediated (in part) by intervening effects on self,esteem. Racial and gender identity similarly have positive effects on adjustment via their intermediary linkages with self,esteem. Structural equation modeling analyses provided support for all of these aspects of the model. Findings also revealed theoretically predicted differences in model parameters across race by gender subgroups. These include a direct effect of prejudice/discrimination events on emotional problems specific to Black youth and an effect of gender identity on self,esteem specific to girls. Black girls appeared to be most vulnerable to exhibiting significant adjustment difficulties as a result of the processes under investigation. [source] Environmental conflict resolution: Evaluating performance outcomes and contributing factorsCONFLICT RESOLUTION QUARTERLY, Issue 1 2009Kirk Emerson This empirical study of fifty-two environmental conflict resolution (ECR) processes is based on an evaluation framework that specifies key conditions and factors that contribute to ECR outcomes. Data were collected on a range of ECR processes and applications. This article reports on findings from a multilevel modeling analysis that focuses on three primary outcomes: reaching agreement, the quality of agreement, and improved working relationships among parties. Effective engagement of parties is identified as a major contributor to all three outcomes. Other key factors that operate directly and indirectly through effective engagement are involvement of appropriate parties, the skills and practices of ECR mediators and facilitators, and incorporation of relevant and high-quality information. Findings generally support the ECR evaluation framework. [source] A molecular modeling analysis of polycyclic aromatic hydrocarbon biodegradation by naphthalene dioxygenaseENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 4 2006Kristine H. Wammer Abstract A theoretical analysis was performed to examine the role of naphthalene dioxygenase(NDO) enzymes in determining differences in biodegradability and biodegradation rates of two- to four-ring polycyclic aromatic hydrocarbons (PAHs) via oxygenation and desaturation reactions. Investigation of the thermodynamics of PAH biodegradation reactions catalyzed by NDO revealed that enthalpies of reaction can explain reaction patterns or regioselectivity of the enzyme in limited cases. Molecular modeling analysis of the size and shape constraints of PAH-enzyme interactions suggests that PAHs bigger than approximately four rings and compounds with , substituents or other structural features contributing to increased width at the end of the substrate near the active site are expected to have binding difficulties. This explains some regioselectivity observations, in that thermody-namically favorable sites on some PAH molecules cannot be positioned correctly to be oxidized at the active site. The enzyme fit analysis also suggests that slower biodegradation rates are expected for compounds with larger widths because of the unique positioning that is required for reaction to occur. An inverse relationship between a molecular descriptor of compound width and previously obtained biodegradation rates suggests that this descriptor may be valuable for predicting relative biodegradation rates of PAHs with dioxygenases other than NDO. [source] Lagged effects of experimental warming and doubled precipitation on annual and seasonal aboveground biomass production in a tallgrass prairieGLOBAL CHANGE BIOLOGY, Issue 12 2008REBECCA A. SHERRY Abstract Global climate change is expected to result in a greater frequency of extreme weather, which can cause lag effects on aboveground net primary production (ANPP). However, our understanding of lag effects is limited. To explore lag effects following extreme weather, we applied four treatments (control, doubled precipitation, 4 °C warming, and warming plus doubled precipitation) for 1 year in a randomized block design and monitored changes in ecosystem processes for 3 years in an old-field tallgrass prairie in central Oklahoma. Biomass was estimated twice in the pretreatment year, and three times during the treatment and posttreatment years. Total plant biomass was increased by warming in spring of the treatment year and by doubled precipitation in summer. However, double precipitation suppressed fall production. During the following spring, biomass production was significantly suppressed in the formerly warmed plots 2 months after treatments ceased. Nine months after the end of treatments, fall production remained suppressed in double precipitation and warming plus double precipitation treatments. Also, the formerly warmed plots still had a significantly greater proportion of C4 plants, while the warmed plus double precipitation plots retained a high proportion of C3 plants. The lag effects of warming on biomass did not match the temporal patterns of soil nitrogen availability determined by plant root simulator probes, but coincided with warming-induced decreases in available soil moisture in the deepest layers of soil which recovered to the pretreatment pattern approximately 10 months after the treatments ceased. Analyzing the data with an ecosystem model showed that the lagged temporal patterns of effects of warming and precipitation on biomass can be fully explained by warming-induced differences in soil moisture. Thus, both the experimental results and modeling analysis indicate that water availability regulates lag effects of warming on biomass production. [source] Modeled interactive effects of precipitation, temperature, and [CO2] on ecosystem carbon and water dynamics in different climatic zonesGLOBAL CHANGE BIOLOGY, Issue 9 2008YIQI LUO Abstract Interactive effects of multiple global change factors on ecosystem processes are complex. It is relatively expensive to explore those interactions in manipulative experiments. We conducted a modeling analysis to identify potentially important interactions and to stimulate hypothesis formulation for experimental research. Four models were used to quantify interactive effects of climate warming (T), altered precipitation amounts [doubled (DP) and halved (HP)] and seasonality (SP, moving precipitation in July and August to January and February to create summer drought), and elevated [CO2] (C) on net primary production (NPP), heterotrophic respiration (Rh), net ecosystem production (NEP), transpiration, and runoff. We examined those responses in seven ecosystems, including forests, grasslands, and heathlands in different climate zones. The modeling analysis showed that none of the three-way interactions among T, C, and altered precipitation was substantial for either carbon or water processes, nor consistent among the seven ecosystems. However, two-way interactive effects on NPP, Rh, and NEP were generally positive (i.e. amplification of one factor's effect by the other factor) between T and C or between T and DP. A negative interaction (i.e. depression of one factor's effect by the other factor) occurred for simulated NPP between T and HP. The interactive effects on runoff were positive between T and HP. Four pairs of two-way interactive effects on plant transpiration were positive and two pairs negative. In addition, wet sites generally had smaller relative changes in NPP, Rh, runoff, and transpiration but larger absolute changes in NEP than dry sites in response to the treatments. The modeling results suggest new hypotheses to be tested in multifactor global change experiments. Likewise, more experimental evidence is needed for the further improvement of ecosystem models in order to adequately simulate complex interactive processes. [source] Natural Attenuation Reactions at a Uranium Mill Tailings Site, Western U.S.A.GROUND WATER, Issue 1 2002Chen Zhu This paper presents a modeling analysis of the geochemical evolution of a contaminated sandy aquifer at a uranium mill tailings site in the western United States. The tailings pond contains fluids having a pH of 1.5 to 3.5 and high levels of As, Be, Cd, Cr, Pb, Mo, Ni, Se, 226Ra, 228Ra, 230Th, 238U, and 234U. Seepage of tailings fluids into the aquifer has formed a low-pH ground water plume. The reclamation plan is to install a low-permeability cover on the tailings pond to stop the seepage and allow the plume to be attenuated by reactions with the aquifer matrix and flushed by uncontaminated upgradient ground water. To evaluate this reclamation scenario, ground water and sediment core samples were analyzed along one flowpath. Speciation-solubility and mass-transfer modeling revealed two sets of chemical reactions for acid seepage and flushing, respectively. The current concentrations and distribution of ground water constituents can be interpreted as being controlled by stepwise pH-buffer reactions with calcite, amorphous aluminum hydroxide, and amorphous iron hydroxides. These buffer reactions divide the aquifer into zones of near-constant pH, separated by interface zones. For the flushing stage, it is predicted that reactions with surface-bound species will dominate the reaction paths, and more pore volumes are required to neutralize the plume than predicted by models that do not consider surface reactions. Direct mineralogical and surface analysis is needed to substantiate this assertion. [source] Fusion core structure of the severe acute respiratory syndrome coronavirus (SARS-CoV): In search of potent SARS-CoV entry inhibitorsJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 6 2008Ling-Hon Matthew Chu Abstract Severe acute respiratory coronavirus (SARS-CoV) spike (S) glycoprotein fusion core consists of a six-helix bundle with the three C-terminal heptad repeat (HR2) helices packed against a central coiled-coil of the other three N-terminal heptad repeat (HR1) helices. Each of the three peripheral HR2 helices shows prominent contacts with the hydrophobic surface of the central HR1 coiled-coil. The concerted protein,protein interactions among the HR helices are responsible for the fusion event that leads to the release of the SARS-CoV nucleocapsid into the target host-cell. In this investigation, we applied recombinant protein and synthetic peptide-based biophysical assays to characterize the biological activities of the HR helices. In a parallel experiment, we employed a HIV-luc/SARS pseudotyped virus entry inhibition assay to screen for potent inhibitory activities on HR peptides derived from the SARS-CoV S protein HR regions and a series of other small-molecule drugs. Three HR peptides and five small-molecule drugs were identified as potential inhibitors. ADS-J1, which has been used to interfere with the fusogenesis of HIV-1 onto CD4+ cells, demonstrated the highest HIV-luc/SARS pseudotyped virus-entry inhibition activity among the other small-molecule drugs. Molecular modeling analysis suggested that ADS-J1 may bind to the deep pocket of the hydrophobic groove on the surface of the central coiled-coil of SARS-CoV S HR protein and prevent the entrance of the SARS-CoV into the host cells. J. Cell. Biochem. 104: 2335,2347, 2008. © 2008 Wiley-Liss, Inc. [source] Experimental and modeling analysis of diffusive release from single-shell microcapsulesAICHE JOURNAL, Issue 11 2009Enrique Muñoz Tavera Abstract There is much experimental and mathematical work that describes chemical transport from multilayered films of planar geometries. There is less so, however, for chemical transport from multilayered spheres, a common structure for controlled-release materials. Based on the Sturm,Liouville approach of Ramkrishna and Amundson (1974), explicit analytical solutions for the concentration profiles and release kinetics from spherical capsules are presented. Fluorescent dye-release studies using single-shelled microspheres called nanoparticle-assembled capsules were performed to validate the model for uniformly and nonuniformly sized capsules. The combined experiment-modeling approach allows optical microscopy images and release measurements to be readily analyzed for estimating diffusion coefficients in capsule core and shell walls. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Nonprofit competition in the grants marketplaceNONPROFIT MANAGEMENT & LEADERSHIP, Issue 1 2010Exploring the relationship between nonprofit financial ratios, grant amount In this study, we test the impact of nonprofit financial health and financial efficiency ratios on the grant amount awarded by foundations using the Georgia grants marketplace as a case. Using hierarchical linear modeling analysis, we can understand the effects of these ratios both within and across foundation grant portfolios. We found statistically significant evidence that grantees with higher debt ratios and higher fundraising ratios receive lower grant amounts. We did not find statistically significant impacts for administrative ratios, revenue diversification, and surplus margin. [source] Women's Perspective on Men's Control and Aggression in Intimate RelationshipsAMERICAN JOURNAL OF ORTHOPSYCHIATRY, Issue 2 2009Zeev Winstok PhD The relationship of men's self-control capability; their need to control their wives; and their use of verbal aggression, threats, and physical forms of aggression against their partners, as reported by women, were examined. Data were obtained from a stratified probability sample of 2,544 women drawn from the general population in Israel. Initially, structural equation modeling analysis showed that (a) men's need to control their partners and their ability to control themselves were negatively related, and were 2 aspects of personal control; (b) men's verbal aggression, threats of physical aggression and actual physical aggression toward their partners were closely related, and were 3 aspects of aggressive behavior; (c) personal control and aggressive behavior were closely related. Next, a revised model that fitted the data better, demonstrated that verbal aggression was more closely related to personal control than to aggressive behavior. Finally, a model representing co-occurrence of control and violent expressions was tested. This model yielded the best fit to the data. We concluded that control and aggression are two conceptualizations of the same phenomenon, rather than 2 distinct, yet interrelated, concepts. [source] Skin Testing in Predicting Response to Nasal Provocation with Alternaria,THE LARYNGOSCOPE, Issue 8 2004John H. Krouse MD Abstract Objective: Examine the efficacy of epicutaneous and intradermal testing in predicting response to nasal provocation with Alternaria antigen. Study Design and Setting: Prospective study. Subjects were tested with the Multi-Test II (MT) epicutaneous testing device. Subjects with negative wheals were then tested with a 1:500 weight:volume intradermal injection of Alternaria. They had baseline assessment of nasal cross-sectional area (CSA) using acoustic rhinometry and underwent nasal provocation with increasing Alternaria concentrations. CSA was assessed at each concentration. A nasal allergen provocation score (NAP) of nasal symptoms as well as a nasal visual analogue scale (VAS) were also completed with each concentration. Results: Sensitivity and specificity of MT in predicting nasal response to Alternaria were poor at 42% and 44%, respectively. The addition of intradermal testing increased sensitivity only modestly to 58%. hierarchical linear modeling analysis demonstrated that subjects positive to Alternaria on skin testing did not show a significant reduction in nasal CSA on acoustic rhinometry or significant elevations in two nasal symptom scores with direct nasal provocation. Conclusion and Significance: Skin testing with either epicutaneous or intradermal testing may not be an accurate or sufficient technique in the assessment of Alternaria reactivity. These results suggest that mold allergies may involve more complex immune mechanisms than simply an immunoglobulin (Ig)E mediated type I immediate hypersensitivity response alone. An alternate model for mold sensitivity, as well as modifications in testing methods, may be required in the evaluation of mold allergy. [source] Magnesium Sulfate versus Placebo for Paroxysmal Atrial Fibrillation: A Randomized Clinical TrialACADEMIC EMERGENCY MEDICINE, Issue 4 2009Kevin Chu MBBS Abstract Objectives:, The objective was to investigate the efficacy of magnesium sulfate (MgSO4) in decreasing the ventricular rate in emergency department (ED) patients presenting with new-onset, rapid atrial fibrillation (AF). Methods:, A double-blinded, placebo-controlled randomized clinical trial was conducted in an adult university hospital. Patients aged ,18 years with AF onset of less than 48 hours and a sustained ventricular rate of >100 beats/min were randomized to either intravenous (IV) MgSO4 10 mmol or normal saline (NSal). Rhythm and instantaneous heart rate as measured by the monitor were recorded at baseline and every 15 minutes for 2 hours after starting the trial drug. Heart rate and rhythm were compared at 2 hours. A multilevel modeling analysis was performed to adjust for differences in baseline heart rate and any additional treatment and to examine changes in heart rate over time. Results:, Twenty-four patients were randomized to MgSO4 and 24 to NSal. Baseline heart rate was lower in the MgSO4 group (mean ± standard deviation [±SD] = 125 ± 24 vs. 140 ± 21 beats/min]. One and 3 patients in the MgSO4 and NSal groups, respectively, were given another antiarrhythmic or were electrically cardioverted within 2 hours after starting the trial drug. Heart rate (mean ± SD) at 2 hours in both MgSO4 (116 ± 30 beats/min) and NSal groups (114 ± 31 beats/min) decreased below their respective baseline levels. However, the rate of heart rate decrease across time did not differ between groups (p = 0.124). The proportion of patients who converted to sinus rhythm 2 hours post,trial drug did not differ (MgSO4 8.7% vs. NSal 25.0%, p = 0.25). Conclusions:, This study was unable to demonstrate a difference between IV MgSO4 10 mmol and saline placebo for reducing heart rate or conversion to sinus rhythm at 2 hours posttreatment in ED patients with AF of less than 48 hours duration. [source] | ||||||||||||||||||||||