Are There Topological Black Hole Solitons in String Theory?

We point out that the celebrated Hawking effect of quantum instability of black holes seems to be related to a nonperturbative effect in string theory. Studying quantum dynamics of strings in the gravitational background of black holes we find classical instability due to emission of massless string excitations. The topology of a black hole seems to play a fundamental role in developing the string theory classical instability due to the effect of sigma model instantons. We argue that string theory allows for a qualitative description of black holes with very small masses and it predicts topological solitons with quantized spectrum of masses. These solitons would not decay into string massless excitations but could be pair created and may annihilate also. Semiclassical mass quantization of topological solitons in string theory is based on the argument showing existence of nontrivial zeros of beta function of the renormalization group.Comment: 12 pages, TeX, requires phyzzx.tex, published in Gen. Rel. Grav. 19 (1987) 1173; comment added on December 18, 199

Normalized power priors always discount historical data

Power priors are used for incorporating historical data in Bayesian analyses by taking the likelihood of the historical data raised to the power α as the prior distribution for the model parameters. The power parameter α is typically unknown and assigned a prior distribution, most commonly a beta distribution. Here, we give a novel theoretical result on the resulting marginal posterior distribution of α in case of the normal and binomial model. Counterintuitively, when the current data perfectly mirror the historical data and the sample sizes from both data sets become arbitrarily large, the marginal posterior of α does not converge to a point mass at α=1 but approaches a distribution that hardly differs from the prior. The result implies that a complete pooling of historical and current data is impossible if a power prior with beta prior for α is used

CR Structures and Asymptotically Flat Space-Times

We discuss the unique existence, arising by analogy to that in algebraically special space-times, of a CR structure realized on null infinity for any asymptotically flat Einstein or Einstein-Maxwell space-time.Comment: 6 page

Dust Migration and Morphology in Optically Thin Circumstellar Gas Disks

We analyze the dynamics of gas-dust coupling in the presence of stellar radiation pressure in circumstellar gas disks, which are in a transitional stage between the gas-dominated, optically thick, primordial nebulae, and the dust-dominated, optically thin Vega-type disks. Dust undergo radial migration, seeking a stable equilibrium orbit in corotation with gas. The migration of dust gives rise to radial fractionation of dust and creates a variety of possible observed disk morphologies, which we compute by considering the equilibrium between the dust production and the dust-dust collisions removing particles from their equilibrium orbits. Sand-sized and larger grains are distributed throughout most of the gas disk, with concentration near the gas pressure maximum in the inner disk. Smaller grains (typically in the range of 10 to 200 micron) concentrate in a prominent ring structure in the outer region of the gas disk (presumably at radius 100 AU), where gas density is rapidly declining with radius. The width and density, as well as density contrast of the dust ring with respect to the inner dust disk depend on the distribution of gas. Our results open the prospect for deducing the distribution of gas in circumstellar disks by observing their dust. We have qualitatively compared our models with two observed transitional disks around HR 4796A and HD 141569A. Dust migration can result in observation of a ring or a bimodal radial dust distribution, possibly very similar to the ones produced by gap-opening planet(s) embedded in the disk, or shepherding it from inside or outside. We conclude that a convincing planet detection via dust imaging should include specific non-axisymmetric structure following from the dynamical simulations of perturbed disks.Comment: 27 pages, 16 figures, submitted to Ap

Computational Aeroelastic Analysis of the Ares Launch Vehicle During Ascent

This paper presents the static and dynamic computational aeroelastic (CAE) analyses of the Ares crew launch vehicle (CLV) during atmospheric ascent. The influence of launch vehicle flexibility on the static aerodynamic loading and integrated aerodynamic force and moment coefficients is discussed. The ultimate purpose of this analysis is to assess the aeroelastic stability of the launch vehicle along the ascent trajectory. A comparison of analysis results for several versions of the Ares CLV will be made. Flexible static and dynamic analyses based on rigid computational fluid dynamic (CFD) data are compared with a fully coupled aeroelastic time marching CFD analysis of the launch vehicle

Zirconium metal-water oxidation kinetics. I. Thermometry

A description is given of the thermometry techniques used in the Zirconium Metal--Water Oxidation Kinetics Program. Temperature measurements in the range 900 to 1500$sup 0$C are made in three experimental systems: two oxidation apparatuses and the annealing furnace used in a corollary study of the diffusion of oxygen in $beta$-Zircaloy. Carefully calibrated Pt vs Pt--10 percent Rh thermocouples are employed in all three apparatuses, while a Pt--6 percent Rh vs Pt-- 30 percent Rh thermocouple and an optical pyrometer are used in addition in the annealing furnace. Features of the experimental systems pertaining to thermocouple installation, temperature control, emf measurements, etc. are described, and potential temperature-measurement error sources are discussed in detail. The accuracy of the temperature measurements is analyzed

Conformal Invariance and Cosmic Background Radiation

The spectrum and statistics of the cosmic microwave background radiation (CMBR) are investigated under the hypothesis that scale invariance of the primordial density fluctuations should be promoted to full conformal invariance. As in the theory of critical phenomena, this hypothesis leads in general to deviations from naive scaling. The spectral index of the two-point function of density fluctuations is given in terms of the quantum trace anomaly and is greater than one, leading to less power at large distance scales than a strict Harrison-Zel'dovich spectrum. Conformal invariance also implies non-gaussian statistics for the higher point correlations and in particular, it completely determines the large angular dependence of the three-point correlations of the CMBR.Comment: 4 pages, Revtex file, uuencoded with one figur

Association Between Residential Greenness and Cardiovascular Disease Risk

Background Exposure to green vegetation has been linked to positive health, but the pathophysiological processes affected by exposure to vegetation remain unclear. To study the relationship between greenness and cardiovascular disease, we examined the association between residential greenness and biomarkers of cardiovascular injury and disease risk in susceptible individuals. Methods and Results In this cross-sectional study of 408 individuals recruited from a preventive cardiology clinic, we measured biomarkers of cardiovascular injury and risk in participant blood and urine. We estimated greenness from satellite-derived normalized difference vegetation index ( NDVI ) in zones with radii of 250 m and 1 km surrounding the participants' residences. We used generalized estimating equations to examine associations between greenness and cardiovascular disease biomarkers. We adjusted for residential clustering, demographic, clinical, and environmental variables. In fully adjusted models, contemporaneous NDVI within 250 m of participant residence was inversely associated with urinary levels of epinephrine (-6.9%; 95% confidence interval, -11.5, -2.0/0.1 NDVI ) and F2-isoprostane (-9.0%; 95% confidence interval, -15.1, -2.5/0.1 NDVI ). We found stronger associations between NDVI and urinary epinephrine in women, those not on β-blockers, and those who had not previously experienced a myocardial infarction. Of the 15 subtypes of circulating angiogenic cells examined, 11 were inversely associated (8.0-15.6% decrease/0.1 NDVI ), whereas 2 were positively associated (37.6-45.8% increase/0.1 NDVI ) with contemporaneous NDVI . Conclusions Independent of age, sex, race, smoking status, neighborhood deprivation, statin use, and roadway exposure, residential greenness is associated with lower levels of sympathetic activation, reduced oxidative stress, and higher angiogenic capacity

Epidemiology of arterial hypertension in patients scheduled for elective hip replacement

Background: Assessment of blood pressure values and early diagnosis of hypertension are especially important in high-risk group, including patients in preoperative and postoperative period. The aim of the current study was the assessment of blood pressure values and prevalence of hypertension in patients undergoing elective hip replacement surgery — an orthopedic procedure associated with one of the highest cardiovascular complication rate. Material and methods: Two hundred and eighty-four consecutive patients admitted for elective hip replacement surgery were screened for arterial hypertension. All patients had their medical records reviewed for prior diagnosis and had their blood pressure measured on admission by a qualified physician prior to the procedure, according to the current guidelines. Results: The mean age of the study population was 62.2 ± 13.9 years and 42.7% of the patients were male. The body mass index (BMI) in the study population was 27.0 ± 4.2 kg/m2. Fifty-eight point two percent of patients were diagnosed with arterial hypertension previously. Mean blood pressure values on admission for systolic blood pressure (SBP) and diastolic blood pressure (DBP) were 134.5 ± 20.4 and 78.6 ± 13.1 mm Hg, respectively. In 43.2% of patients, the on admission blood pressure values exceeded the threshold of ≥ 140 and/or 90 mm Hg. Arterial hypertension was diagnosed de novo in 33 (15.0%) patients. Patients with the disease were older (67.5 ± 12.3 vs. 54.4 ± 13.9 years; p < 0.0001), and had higher BMI (27.6 ± 4.3 vs. 26.2 ± 3.8 kg/m2; p = 0.05) than patients without the diagnosed disease. Diabetes mellitus was more often found in hypertensive patients (13.3% vs. 3.3%; p = 0.02), they also more often had history of myocardial infarction (p = 0.02), stable coronary artery disease (p = 0.001) and heart failure (p = 0.006) compared to patients without the diagnosis. Conclusions: The majority of patients scheduled for elective hip replacement surgery is diagnosed with arterial hypertension. The disease is also diagnosed de novo in 15% of these patients. Screening for arterial hypertension is important in this group of patients and can potentially reduce the complication rates of the hip replacement surgery.Background: Assessment of blood pressure values and early diagnosis of hypertension are especially important in high-risk group, including patients in preoperative and postoperative period. The aim of the current study was the assessment of blood pressure values and prevalence of hypertension in patients undergoing elective hip replacement surgery — an orthopedic procedure associated with one of the highest cardiovascular complication rate. Material and methods: Two hundred and eighty-four consecutive patients admitted for elective hip replacement surgery were screened for arterial hypertension. All patients had their medical records reviewed for prior diagnosis and had their blood pressure measured on admission by a qualified physician prior to the procedure, according to the current guidelines. Results: The mean age of the study population was 62.2 ± 13.9 years and 42.7% of the patients were male. The body mass index (BMI) in the study population was 27.0 ± 4.2 kg/m2. Fifty-eight point two percent of patients were diagnosed with arterial hypertension previously. Mean blood pressure values on admission for systolic blood pressure (SBP) and diastolic blood pressure (DBP) were 134.5 ± 20.4 and 78.6 ± 13.1 mm Hg, respectively. In 43.2% of patients, the on admission blood pressure values exceeded the threshold of ≥ 140 and/or 90 mm Hg. Arterial hypertension was diagnosed de novo in 33 (15.0%) patients. Patients with the disease were older (67.5 ± 12.3 vs. 54.4 ± 13.9 years; p < 0.0001), and had higher BMI (27.6 ± 4.3 vs. 26.2 ± 3.8 kg/m2; p = 0.05) than patients without the diagnosed disease. Diabetes mellitus was more often found in hypertensive patients (13.3% vs. 3.3%; p = 0.02), they also more often had history of myocardial infarction (p = 0.02), stable coronary artery disease (p = 0.001) and heart failure (p = 0.006) compared to patients without the diagnosis. Conclusions: The majority of patients scheduled for elective hip replacement surgery is diagnosed with arterial hypertension. The disease is also diagnosed de novo in 15% of these patients. Screening for arterial hypertension is important in this group of patients and can potentially reduce the complication rates of the hip replacement surgery