185 research outputs found
Colliding Kaluza-Klein Bubbles
We construct an exact solution describing the collision of two Kaluza-Klein
"bubbles of nothing" in 3+1 dimensions. When the bubbles collide, a curvature
singularity forms which is hidden inside an event horizon. However, unlike the
formation of ordinary black holes, in this case the spacetime resembles the
entire maximally extended Schwarzschild solution. We also point out that there
are inequivalent bubbles that can be constructed from Kerr black holes.Comment: 20 pages, v2: minor error correcte
Uniqueness and non-uniqueness of static vacuum black holes in higher dimensions
We prove the uniqueness theorem for asymptotically flat static vacuum black
hole solutions in higher dimensional space-times. We also construct infinitely
many non-asymptotically flat regular static black holes on the same spacetime
manifold with the same spherical topology.Comment: to appear in Progress of Theoretical Physics Supplement No. 14
Rotating Black Holes which Saturate a Bogomol'nyi Bound
We construct and study the electrically charged, rotating black hole solution
in heterotic string theory compactified on a dimensional torus. This
black hole is characterized by its mass, angular momentum, and a
dimensional electric charge vector. One of the novel features of this solution
is that for , its extremal limit saturates the Bogomol'nyi bound. This is
in contrast with the case where the rotating black hole solution develops
a naked singularity before the Bogomol'nyi bound is reached. The extremal black
holes can be superposed, and by taking a periodic array in , one obtains
effectively four dimensional solutions without naked singularities.Comment: 13 pages, no figure
Uniqueness of (dilatonic) charged black holes and black p-branes in higher dimensions
We prove the uniqueness of higher dimensional (dilatonic) charged black holes
in static and asymptotically flat spacetimes for arbitrary vector-dilaton
coupling constant. An application to the uniqueness of a wide class of black
p-branes is also given.Comment: 6 page
Self-tuning in an Outgoing Brane Wave Model
We introduce a new brane-world model in which the bulk solution consists of
outgoing plane waves. This is an exact solution to string theory with no naked
singularities. The recently discussed self-tuning mechanism to cancel the
cosmological constant on a brane is naturally incorporated. We show that even
if the vacuum energy on the brane changes, e.g. due to a phase transition, the
brane geometry remains insensitive to the local vacuum energy. We also consider
the static self-tuning branes introduced earlier, and find a solution in which
the brane geometry starts to contract when the vacuum energy on the brane
changes.Comment: 20 pages, 3 figures, latex; v2: minor correction and reference adde
The Alberta Heart Failure Etiology and Analysis Research Team (HEART) study
Background Nationally, symptomatic heart failure affects 1.5-2% of Canadians, incurs $3 billion in hospital costs annually and the global burden is expected to double in the next 1–2 decades. The current one-year mortality rate after diagnosis of heart failure remains high at >25%. Consequently, new therapeutic strategies need to be developed for this debilitating condition.
Methods/Design The objective of the Alberta HEART program (http://albertaheartresearch.ca) is to develop novel diagnostic, therapeutic and prognostic approaches to patients with heart failure with preserved ejection fraction. We hypothesize that novel imaging techniques and biomarkers will aid in describing heart failure with preserved ejection fraction. Furthermore, the development of new diagnostic criteria will allow us to: 1) better define risk factors associated with heart failure with preserved ejection fraction; 2) elucidate clinical, cellular and molecular mechanisms involved with the development and progression of heart failure with preserved ejection fraction; 3) design and test new therapeutic strategies for patients with heart failure with preserved ejection fraction. Additionally, Alberta HEART provides training and education for enhancing translational medicine, knowledge translation and clinical practice in heart failure. This is a prospective observational cohort study of patients with, or at risk for, heart failure. Patients will have sequential testing including quality of life and clinical outcomes over 12 months. After that time, study participants will be passively followed via linkage to external administrative databases. Clinical outcomes of interest include death, hospitalization, emergency department visits, physician resource use and/or heart transplant. Patients will be followed for a total of 5 years.
Discussion Alberta HEART has the primary objective to define new diagnostic criteria for patients with heart failure with preserved ejection fraction. New criteria will allow for targeted therapies, diagnostic tests and further understanding of the patients, both at-risk for and with heart failure
Avpr1a variant associated with preschoolers' lower altruistic behavior
10.1371/journal.pone.0025274PLoS ONE69
The Oxytocin Receptor (OXTR) Contributes to Prosocial Fund Allocations in the Dictator Game and the Social Value Orientations Task
Background: Economic games observe social decision making in the laboratory that involves real money payoffs. Previously we have shown that allocation of funds in the Dictator Game (DG), a paradigm that illustrates costly altruistic behavior, is partially determined by promoter-region repeat region variants in the arginine vasopressin 1a receptor gene (AVPR1a). In the current investigation, the gene encoding the related oxytocin receptor (OXTR) was tested for association with the DG and a related paradigm, the Social Values Orientation (SVO) task. Methodology/Principal Findings: Association (101 male and 102 female students) using a robust-family based test between 15 single tagging SNPs (htSNPs) across the OXTR was demonstrated with both the DG and SVO. Three htSNPs across the gene region showed significant association with both of the two games. The most significant association was observed with rs1042778 (p = 0.001). Haplotype analysis also showed significant associations for both DG and SVO. Following permutation test adjustment, significance was observed for 2–5 locus haplotypes (p,0.05). A second sample of 98 female subjects was subsequently and independently recruited to play the dictator game and was genotyped for the three significant SNPs found in the first sample. The rs1042778 SNP was shown to be significant for the second sample as well (p = 0.004, Fisher’s exact test). Conclusions: The demonstration that genetic polymorphisms for the OXTR are associated with human prosocial decisio
Economic Analysis of Knowledge: The History of Thought and the Central Themes
Following the development of knowledge economies, there has been a rapid expansion of economic analysis of knowledge, both in the context of technological knowledge in particular and the decision theory in general. This paper surveys this literature by identifying the main themes and contributions and outlines the future prospects of the discipline. The wide scope of knowledge related questions in terms of applicability and alternative approaches has led to the fragmentation of research. Nevertheless, one can identify a continuing tradition which analyses various aspects of the generation, dissemination and use of knowledge in the economy
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