Exotic Spaces in Quantum Gravity I: Euclidean Quantum Gravity in Seven Dimensions

It is well known that in four or more dimensions, there exist exotic manifolds; manifolds that are homeomorphic but not diffeomorphic to each other. More precisely, exotic manifolds are the same topological manifold but have inequivalent differentiable structures. This situation is in contrast to the uniqueness of the differentiable structure on topological manifolds in one, two and three dimensions. As exotic manifolds are not diffeomorphic, one can argue that quantum amplitudes for gravity formulated as functional integrals should include a sum over not only physically distinct geometries and topologies but also inequivalent differentiable structures. But can the inclusion of exotic manifolds in such sums make a significant contribution to these quantum amplitudes? This paper will demonstrate that it will. Simply connected exotic Einstein manifolds with positive curvature exist in seven dimensions. Their metrics are found numerically; they are shown to have volumes of the same order of magnitude. Their contribution to the semiclassical evaluation of the partition function for Euclidean quantum gravity in seven dimensions is evaluated and found to be nontrivial. Consequently, inequivalent differentiable structures should be included in the formulation of sums over histories for quantum gravity.Comment: AmsTex, 23 pages 5 eps figures; replaced figures with ones which are hopefully viewable in pdf forma

Manifolds with almost nonnegative curvature operator and principal bundles

We study manifolds with almost nonnegative curvature operator (ANCO) and provide first examples of closed simply connected ANCO mannifolds that do not admit nonnegative curvature operator

A tissue-specific landscape of sense/antisense transcription in the mouse intestine

<p>Abstract</p> <p>Background</p> <p>The intestinal mucosa is characterized by complex metabolic and immunological processes driven highly dynamic gene expression programs. With the advent of next generation sequencing and its utilization for the analysis of the RNA sequence space, the level of detail on the global architecture of the transcriptome reached a new order of magnitude compared to microarrays.</p> <p>Results</p> <p>We report the ultra-deep characterization of the polyadenylated transcriptome in two closely related, yet distinct regions of the mouse intestinal tract (small intestine and colon). We assessed tissue-specific transcriptomal architecture and the presence of novel transcriptionally active regions (nTARs). In the first step, signatures of 20,541 NCBI RefSeq transcripts could be identified in the intestine (74.1% of annotated genes), thereof 16,742 are common in both tissues. Although the majority of reads could be linked to annotated genes, 27,543 nTARs not consistent with current gene annotations in RefSeq or ENSEMBL were identified. By use of a second independent strand-specific RNA-Seq protocol, 20,966 of these nTARs were confirmed, most of them in vicinity of known genes. We further categorized our findings by their relative adjacency to described exonic elements and investigated regional differences of novel transcribed elements in small intestine and colon.</p> <p>Conclusions</p> <p>The current study demonstrates the complexity of an archetypal mammalian intestinal mRNA transcriptome in high resolution and identifies novel transcriptionally active regions at strand-specific, single base resolution. Our analysis for the first time shows a strand-specific comparative picture of nTARs in two tissues and represents a resource for further investigating the transcriptional processes that contribute to tissue identity.</p

Reactive oxygen species in phagocytic leukocytes

Phagocytic leukocytes consume oxygen and generate reactive oxygen species in response to appropriate stimuli. The phagocyte NADPH oxidase, a multiprotein complex, existing in the dissociated state in resting cells becomes assembled into the functional oxidase complex upon stimulation and then generates superoxide anions. Biochemical aspects of the NADPH oxidase are briefly discussed in this review; however, the major focus relates to the contributions of various modes of microscopy to our understanding of the NADPH oxidase and the cell biology of phagocytic leukocytes

A de Rham isomorphism in singular cohomology and Stokes theorem for stratifolds

We study the de Rham cohomology of a class of spaces with singularities which are called stratifolds. Such spaces occur in mathematical and theoretical physics. We generalize two classical results from the analysis of smooth manifolds, with outstanding applications in physics, to the class of stratifolds. The first one is Stokes theorem, the second one is the de Rham theorem which states that the de Rham cohomology of a stratifold is isomorphic to its singular cohomology with coefficients in ℝ. In fact, we give an explicit geometric construction of this isomorphism, given by integrating forms over stratifol

Cost effectiveness of ibandronate for the prevention of fractures in inflammatory bowel disease-related osteoporosis: Cost-utility analysis using a Markov model.

Osteoporosis is a frequent complication in patients with inflammatory bowel disease. Recent studies have shown bisphosphonates to considerably reduce fracture risk in patients with osteoporosis, and preventing fractures with bisphosphonates has been reported to be cost effective in older populations. However, no studies of the cost effectiveness of these agents in preventing fractures in patients with inflammatory bowel disease are available. OBJECTIVE: To investigate the cost effectiveness of the bisphosphonate ibandronate combined with calcium/colecalciferol (&#39;ibandronate&#39;) in patients with osteopenia or osteoporosis due to inflammatory bowel disease in Germany. Treatment strategies used for comparison were sodium fluoride combined with calcium/colecalciferol (&#39;fluoride&#39;) and calcium/colecalciferol (&#39;calcium&#39;) alone. STUDY DESIGN AND METHODS: A cost-utility analysis was conducted using data from a randomized controlled trial (RCT). Changes in bone mineral density (BMD) were adjusted and predicted for a standardized population receiving each respective treatment. A Markov model was developed, with probabilities of transition to fracture states consisting of BMD-dependent and -independent components. The BMD-dependent component was assessed using predicted change in BMD from the RCT. The independent component captured differences in bone quality and micro-architecture resulting from prevalent fractures or treatment with anti-resorptive drugs.The analysis was conducted for a population with a mean age of the RCT patients (women aged 36 years, men aged 38 years) with osteopenia (T-score about -2.0 at baseline), a population of the same age with osteoporosis (T-score of -3.0 at baseline) and for an older population (both sexes aged 65 years) with osteoporosis (T-score of -3.0). Outcomes were measured as costs per QALY gained from a societal perspective. The treatment duration in the RCT was 42 months. A 5-year period was assumed to follow, during which the treatment effects linearly declined to 0. The simulation time was 10 years.Prices for medication and treatment were presented as year 2004 values; costs and effects were discounted at 5%. To test the robustness of the results, univariate and probabilistic sensitivity analyses (Monte Carlo simulation) were conducted. RESULTS: The calcium strategy dominated the fluoride strategy. When the ibandronate strategy was compared with the calcium strategy, the base-case cost-effectiveness ratios (costs per QALY gained) were between euro 407 375 for an older female population with osteoporosis and euro 6 516 345 for a younger female population with osteopenia. Univariate sensitivity analyses resulted in variations between 4% of base-case results and dominance of calcium. In Monte Carlo simulations, conducted for the various populations, the probability of an ICER of ibandronate below euro 50 000 per QALY was never greater than 20.2%. CONCLUSION: The ibandronate strategy is unlikely to be considered cost effective by decision makers in men or women with characteristics of those in the target population of the RCT, or in older populations with osteoporosis