Swift J164449.3+573451 event: generation in the collapsing star cluster?

We discuss the multiband energy release in a model of a collapsing galactic nucleus, and we try to interpret the unique super-long cosmic gamma-ray event Swift J164449.3+573451 (GRB 110328A by early classification) in this scenario. Neutron stars and stellar-mass black holes can form evolutionary a compact self-gravitating subsystem in the galactic center. Collisions and merges of these stellar remnants during an avalanche contraction and collapse of the cluster core can produce powerful events in different bands due to several mechanisms. Collisions of neutron stars and stellar-mass black holes can generate gamma-ray bursts (GRBs) similar to the ordinary models of short GRB origin. The bright peaks during the first two days may also be a consequence of multiple matter supply (due to matter release in the collisions) and accretion onto the forming supermassive black hole. Numerous smaller peaks and later quasi-steady radiation can arise from gravitational lensing, late accretion of gas onto the supermassive black hole, and from particle acceleration by shock waves. Even if this model will not reproduce exactly all the Swift J164449.3+573451 properties in future observations, such collapses of galactic nuclei can be available for detection in other events.Comment: 7 pages, replaced by the final versio

THERMAL AND MECHANICAL RESPONSES OF FIBER REINFORCED POLYMER COMPOSITES UNDER ONE-SIDED FIRE EXPOSURE

This research investigated the thermal and mechanical responses of fiber reinforced polymer (FRP) composites in fire. The research focused on thermal decomposition and heat transfer, deformation, delamination, and structural integrity of FRP composites. The research was undertaken by thermal and fire testing, and fire dynamics and finite element modeling. To simplify the modeling of the decomposition of FRP composites, an infinite-rate pyrolysis model was incorporated into heat transfer modeling to predict the thermal response of the composite panels under one sided heating. The thermal prediction by the infinite-rate model was compared to the finite-rate model, in which the decomposition was described by Arrhenius equation, and was validated with both bench and intermediate scale fire tests. A concept of shift temperature was introduced into the heat transfer to account for the effect of heating rate on the decomposition temperature. With temperature results given by the heat transfer model, a simplified plane strain model was proposed to predict the mechanical response of FRP composites. Based on a bilinear traction-separation law, cohesive elements in commercial finite element software ABAQUS were incorporated in the mechanical model to consider the effect of delamination for sandwich panels. In order to evaluate the effect of heat flux of a composite's own flame on its thermal response and fire properties, two-layer flame geometry was proposed to predict the effect of flame heat flux on the thermal response of char-forming materials. The total flame heat flux in a typical cone test was estimated based on general turbulent flame temperature and combustible gas temperature. All prediction results were validated with experimental data. It was demonstrated that (1) the modeling of decomposition reaction using the infinite-rate model required less input parameters, (2) a material's own flame had significant influent on its fire reaction properties at the beginning of flaming combustion, (3) the plane-strain model was capable of predicting deformation and time-to-failure with a good accuracy, and (4) cohesive elements can be used to model the delamination of sandwich FRP panels in fire

Cross-shopping and shopping orientation : consumer perceived value in today's dynamic retail environment

"The purpose of this research was to explore and understand better how consumers perceive the value of their shopping experiences in two key retail outlets--mass merchandisers and department stores--as well as how consumers' shopping orientations, recreational or functional, relate to consumer perceived value (CPV). An initial qualitative approach was used, i.e., in-depth, lightly structured interviews, to explore the perceptions consumers have of the value they gain during their shopping experiences in retail stores. Findings from the qualitative study were combined with an in-depth literature review to develop a survey to measure consumers' perceptions of transaction value, acquisition value, efficiency value, choice value, esthetic value, curiosity value, social interaction value, social status value, and self-gratification value when shopping in mass merchandisers and department stores. 800 surveys were disseminated, which resulted in 372 usable questionnaires for analysis, a 46.5% response rate. The findings indicated that consumers do have different levels of perception on some of the value dimensions tested when they shop at mass merchandisers versus department stores. Specifically, consumers perceived higher levels of acquisition value and efficiency value at mass merchandisers than at department stores, and they perceived higher levels of transaction value, esthetic value, curiosity value, social interaction value, social status value, and self-gratification value at department stores than at mass merchandisers. Choice value was not perceived as different when consumers shopped at the two different retail outlets. It was also found that shopping orientation, a recreational or functional shopping approach, significantly affected consumers' value perceptions when they shopped. Recreational shoppers perceived significantly higher levels of all the value dimensions investigated than functional shoppers at both department stores and mass merchandisers. The study results suggest that retailers may first want to target the perceived values most salient to consumers in order to increase their profitability, and, second, they may want to focus on the less salient values identified in the study to gain a better understanding of why consumers rated these values much lower when shopping in their establishments."--Abstract from author supplied metadata

Abstract visualization of large-scale time-varying data

The explosion of large-scale time-varying datasets has created critical challenges for scientists to study and digest. One core problem for visualization is to develop effective approaches that can be used to study various data features and temporal relationships among large-scale time-varying datasets. In this dissertation, we first present two abstract visualization approaches to visualizing and analyzing time-varying datasets. The first approach visualizes time-varying datasets with succinct lines to represent temporal relationships of the datasets. A time line visualizes time steps as points and temporal sequence as a line. They are generated by sampling the distributions of virtual words across time to study temporal features. The key idea of time line is to encode various data properties with virtual words. We apply virtual words to characterize feature points and use their distribution statistics to measure temporal relationships. The second approach is ensemble visualization, which provides a highly abstract platform for visualizing an ensemble of datasets. Both approaches can be used for exploration, analysis, and demonstration purposes. The second component of this dissertation is an animated visualization approach to study dramatic temporal changes. Animation has been widely used to show trends, dynamic features and transitions in scientific simulations, while animated visualization is new. We present an automatic animation generation approach that simulates the composition and transition of storytelling techniques and synthesizes animations to describe various event features. We also extend the concept of animated visualization to non-traditional time-varying datasets--network protocols--for visualizing key information in abstract sequences. We have evaluated the effectiveness of our animated visualization with a formal user study and demonstrated the advantages of animated visualization for studying time-varying datasets

Exploring the Dose-Response Relationship between Acute Resistance Exercise Intensity and Cognitive Function

The primary purpose of the present research was to explore the dose-response relationship between acute resistance exercise intensity and cognitive performance. A secondary purpose of this study was to use directly statistical techniques to explore the role of exercise-induced arousal as a mediator of the relationship. Sixty-eight participants were recruited and randomly assigned into rest, 40%, 70% or 100% of 10 repetition maximal (10-RM) groups. One-way ANOVA was computed for demographic variables and baseline measures, and regression analyses were computed to examine the effect of exercise intensity as well as exercise-induced arousal on cognitive performance. In addition, mediation analysis was applied to examine exercise-induced arousal as a mediator of this relationship. The results indicated that a 30-minute bout of resistance exercise has a positive impact on both information processing speed and executive function. Specifically, there is a significant linear relationship between exercise intensity and information processing speed. On the other hand, a significant quadratic trend for both exercise intensity and exercise-induced arousal was observed for executive function measures that assess inhibition, selective attention, working memory and attentional flexibility. Exercise-induced arousal was a significant mediator when tested using one of the heart-rate indexes and for one measure of executive function performance. Thus, an acute bout of resistance exercise benefits cognitive performance and there is a dose-response effect of both exercise intensity and exercise-induced arousal on cognitive performance. Future research should explore other potential mediators of the relationship to further our understanding of mechanisms

Adapting and testing a vulnerability model for Latino/a sexual and gender minorities in a new settlement state

Sexual health vulnerability among Latino/a sexual and gender minorities is poorly understood, despite high rates of HIV and STDs among Latino/as, particularly in new settlement states in the southern US. The lack of a model specific to Latino/a sexual and gender minorities complicates the study of vulnerability. To move vulnerability research forward with this population, key constructs must be defined and processes for model development described. Clarity in the operationalization of vulnerability, as well as in the approach for adapting a vulnerability model to Latino/a sexual and gender minorities, can improve replicability to other similar populations and standardize a method toward model development. This study tests a new theoretical model of vulnerability for Latino/a sexual and gender minorities by adapting the General Model of Vulnerability. A community-based participatory research partnership recruited Latino/a sexual and gender minorities (i.e., men who have sex with men and transgender women; N=186) in North Carolina to participate in the HOLA intervention. Using baseline data collected in 2012, I performed latent class analysis to operationalize vulnerability across three domains (i.e., socioeconomic stability, health care, and social) using eight indicators (i.e., educational attainment, employment status, routine check-up, social support, acculturation, racial/ethnic and sexual discrimination, and internalized homonegativity) to identify underlying classes of vulnerability, then tested the association between class membership and three sexual health behaviors (i.e., HIV testing, STD testing, and condom use). In this sample, I identified three latent classes of vulnerability: High Education and Employment (18.8% of the sample; characterized by high educational attainment and employment status), Low Education and High Social Support (63.4%), and High Education and Discrimination (17.7%; high educational attainment and racial/ethnic and sexual discrimination). Membership in the Low Education and High Social Support class and the High Education and Discrimination class was significantly associated with more condomless anal or vaginal intercourse, whereas membership in the High Education and Employment class was associated with less condomless anal or vaginal intercourse (p < 0.05). I found no significant associations between vulnerability and HIV testing nor STD testing. Overall, the results from this study found that the identification of latent classes of vulnerability differentially predicted a sexual health behavior among Latino/a sexual and gender minorities in NC. These findings highlight the utility of identifying typologies of vulnerability to predict patterns of sexual health behavior. This information can be used to tailor future efforts to specific groups of Latino/a sexual and gender minorities, as well as other vulnerable populations living in other parts of the US. Developing intervention components that harness facilitators (e.g., social support) and address barriers (e.g., discrimination) to health, focusing specifically on those uniquely vulnerable, is critical to increasing the reach and effectiveness of tailored health promotion and HIV/STD prevention programming

The moderating effects of job and personal life involvement on the relationship between work/personal life conflict and intention to quit.

This study expands research on work–personal life conflict and intention to quit by exploring the moderating effects of job involvement and personal life involvement on the relationship between work–personal life conflict and an employee's intention to quit. The sample consisted of 295 hotel managers. Personal life involvement was found to have a moderating effect on the relationship between work interference with personal life and intention to quit. The relationship between work interference with personal life and intention to quit was strongest among respondents with the highest levels of personal life involvement. However, employees' job involvement did not moderate the relationship between work–personal life conflict and intention to quit. Recommendations are offered to monitor impacts of work on personal life and to address the retention challenges facing the industry

Spillover between work and personal life balance for lodging managers.

The hospitality and tourism industry is characterized by long and erratic work hours. Many jobs are unsuitable for working at home. The unique features of the lodging industry and the demands of lodging managers' jobs often have interfered with the personal lives and marital relationships of these managers. The situation may even lead to a decision to leave the specific occupation or the industry permanently. The primary goal of this research was to investigate the perspectives of Taiwan hotel managers' regarding work-personal life balance and its relationship to various demographic variables, such as gender, marital status, etc. Results indicate that very few of Taiwanese managers had difficulty balancing work and personal lives. Indeed, the majority of these managers reported their perception of success in balancing work and personal life as from neutral to very successful. No statistically significant differences were found between female and male managers in terms of perceived difficulty or success in work and personal life balance. Neither was there a significant difference among married or single female/male managers. Results also suggested that work interfered with personal life more frequently than personal lif

The Ideal Qualities and Tasks of Library Leaders: Perspectives of Academic, Public, School, and Special Library Administrators

Our study examines the results of 114 interviews with academic, public, school media, and special library administrators collected over a one-year period in North Carolina. Preliminary results suggest that there is a core set of traits shared by administrators across libraries although some variation occurs depending on library environment. Implications center on the ability to inform degree preparation programs and practice by identifying primary qualities of library administration in general and specific to academic, public, school library, and special libraries