University of Kentucky

About: University of Kentucky is a education organization based out in Lexington, Kentucky, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 43933 authors who have published 92195 publications receiving 3256087 citations. The organization is also known as: UK.

Evolution of Stellar Bars in Live Axisymmetric Halos: Recurrent Buckling and Secular Growth

Abstract: Evolution of stellar bars in disk galaxies is accompanied by dynamical instabilities and secular changes. Following the vertical buckling instability, the bars are known to weaken dramatically and develop a pronounced boxy/peanut shape when observed edge-on. Using high-resolution N-body simulations of stellar disks embedded in live axisymmetric dark matter halos, we have investigated the long-term changes in the bar morphology, specifically the evolution of the bar size, its vertical structure, and the exchange of angular momentum. We find that following the initial buckling, the bar resumes its growth from deep inside the corotation radius and follows the ultraharmonic resonance thereafter. We also find that this secular bar growth triggers a spectacular secondary vertical buckling instability that leads to the appearance of characteristic boxy/peanut/X-shaped bulges. The secular bar growth is crucial for the recurrent buckling to develop. Furthermore, the secondary buckling is milder, persists over a substantial period of time, ~3 Gyr, and can have observational counterparts. Overall, the stellar bars show recurrent behavior in their properties and evolve by increasing their linear and vertical extents, both dynamically and secularly. We also demonstrate explicitly that the prolonged growth of the bar is mediated by continuous angular momentum transfer from the disk to the surrounding halo and that this angular momentum redistribution is resonant in nature: a large number of lower resonances trap disk and halo particles, and this trapping is robust, in broad agreement with the earlier results in the literature.

A collaborative approach to ontology design

Abstract: Creating a general ontology characterizing the conduct of knowledge management.

Impact of Symptom Prevalence and Symptom Burden on Quality of Life in Patients with Heart Failure

Abstract: Background: Heart failure is an escalating health problem around the world. Despite significant scientific advances, heart failure patients experience multiple physical and psychological symptoms that can impact the quality of life.Aims: To determine the (1) symptom prevalence, severity, distress and symptom burden in patients with heart failure; (2) impact of age and gender on symptom prevalence, severity, distress and symptom burden; and (3) impact of symptom prevalence and symptom burden on health-related quality of life (HRQOL) in patients with heart failure.Methods: A convenience sample of 53 heart failure patients participated in this descriptive, cross-sectional design. Symptoms and HRQOL were measured using the Memorial Symptom Assessment Scale—Heart Failure and the Minnesota Living with Heart Failure Questionnaire.Results: Patients experienced a mean of 15.1 ± 8.0 symptoms. Shortness of breath and lack of energy were the most prevalent. Difficulty sleeping was the most burdensome symptom. Lower a...

Genome-wide analysis of the interaction between the endosymbiotic bacterium Wolbachia and its Drosophila host

Abstract: Intracellular Wolbachia bacteria are obligate, maternally-inherited, endosymbionts found frequently in insects and other invertebrates. The success of Wolbachia can be attributed in part to an ability to alter host reproduction via mechanisms including cytoplasmic incompatibility (CI), parthenogenesis, feminization and male killing. Despite substantial scientific effort, the molecular mechanisms underlying the Wolbachia/host interaction are unknown. Here, an in vitro Wolbachia infection was generated in the Drosophila S2 cell line, and transcription profiles of infected and uninfected cells were compared by microarray. Differentially-expressed patterns related to reproduction, immune response and heat stress response are observed, including multiple genes that have been previously reported to be involved in the Wolbachia/host interaction. Subsequent in vivo characterization of differentially-expressed products in gonads demonstrates that Angiotensin Converting Enzyme (Ance) varies between Wolbachia infected and uninfected flies and that the variation occurs in a sex-specific manner. Consistent with expectations for the conserved CI mechanism, the observed Ance expression pattern is repeatable in different Drosophila species and with different Wolbachia types. To examine Ance involvement in the CI phenotype, compatible and incompatible crosses of Ance mutant flies were conducted. Significant differences are observed in the egg hatch rate resulting from incompatible crosses, providing support for additional experiments examining for an interaction of Ance with the CI mechanism. Wolbachia infection is shown to affect the expression of multiple host genes, including Ance. Evidence for potential Ance involvement in the CI mechanism is described, including the prior report of Ance in spermatid differentiation, Wolbachia-induced sex-specific effects on Ance expression and an Ance mutation effect on CI levels. The results support the use of Wolbachia infected cell cultures as an appropriate model for predicting in vivo host/Wolbachia interactions.