Graviton Emission in the Bulk from a Higher-Dimensional Schwarzschild Black Hole

We consider the evaporation of (4+n)-dimensional non-rotating black holes into gravitons. We calculate the energy emission rate for gravitons in the bulk obtaining analytical solutions of the master equation satisfied by all three types (S,V,T) of gravitational perturbations. Our results, valid in the low-energy regime, show a vector radiation dominance for every value of n, while the relative magnitude of the energy emission rate of the subdominant scalar and tensor radiation depends on n. The low-energy emission rate in the bulk for gravitons is well below that for a scalar field, due to the absence of the dominant l=0,1 modes from the gravitational spectrum. Higher partial waves though may modify this behaviour at higher energies. The calculated low-energy emission rate, for all types of degrees of freedom decreases with n, although the full energy emission rate, integrated over all frequencies, is expected to increase with n, as in the previously studied case of a bulk scalar field.Comment: 17 pages, 2 figures, minor corrections, accepted by Phys. Lett.

Synthesis and Recognition Properties of Higher Order Tetrathiafulvalene (Ttf) Calix N Pyrroles (N=4-6)

Two new benzoTTF-annulated calix[n]pyrroles (n = 5 and 6) were synthesized via a one-step acid catalyzed condensation reaction and fully characterized via single crystallographic analyses. As compared to the known tetra-TTF annulated calix[4]pyrrole, which is also produced under the conditions of the condensation reaction, the expanded calix[n]pyrroles (n = 5 and 6) are characterized by a larger cavity size and a higher number of TTF units (albeit the same empirical formula). Analysis of the binding isotherms obtained from UV-Vis spectroscopic titrations carried out in CHCl3 in the presence of both anionic (Cl-, Br-, I-, CH3COO-, H2PO4-, and HSO4-) and neutral (1,3,5-trinitrobenzene (TNB) and 2,4,6-trinitrotoluene (TNT)) substrates revealed that as a general rule the calix[6]pyrrole derivative proved to be the most efficient molecular receptor for anions, while the calix[4]pyrrole congener proves most effective for the recognition of TNB and TNT. These findings are rationalized in terms of the number of electron rich TTF subunits and NH hydrogen bond donor groups within the series, as well as an ability to adopt conformations suitable for substrate recognition, and are supported by solid state structural analyses.National Science Foundation CHE 1057904, 0741973Robert A. Welch Foundation F-1018Danish Natural Science Research Council (FNU) 272-08-0047, 11-106744WCU (World Class University) program of Korea R32-2010-10217-0Villum FoundationChemistr

Enhanced light harvesting in bulk heterojunction photovoltaic devices with shape-controlled Ag nanomaterials: Ag nanoparticles versus Ag nanoplates

Enhanced power conversion efficiency (PCE(%)) with improved optical path length from two types of shape controlled silver (Ag) materials (Ag nanoplates versus Ag nanoparticles (NPs)) was studied in poly(3-hexylthiophene) (P3HT)/[6,6]-phenyl C 71 butyric acid methyl-ester (PC 71BM) or poly[N-9′′-hepta-decanyl-2,7-carbazole-alt-5,5-(4′, 7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT)/[6,6]-phenyl C 71 butyric acid methyl-ester (PC 71BM) bulk heterojunction (BHJ) devices. The Ag nanoplates and Ag NPs can be synthesized by simple solution polyol chemistry with well defined size and shape. A BHJ with a 0.5 wt% optimized blend ratio of Ag nanoplates shows improved cell performance and photo-current density than a BHJ with Ag NPs owing to the enhanced light absorption with the results of an excitation of localized surface plasmon and efficient light scattering by the Ag nanoplates embedded BHJ film. When the BHJ is combined with the Ag nanoplates at an optimized ratio of 0.5 wt%, the PCE (%) increases from 3.2% to 4.4% in P3HT/PC 71BM, and from 5.9% to 6.6% in PCDTBT/PC 71BM BHJ devices. © 2012 The Royal Society of Chemistry.1

Greybody factors in a rotating black-hole background-II : fermions and gauge bosons

We study the emission of fermion and gauge boson degrees of freedom on the brane by a rotating higher-dimensional black hole. Using matching techniques, for the near-horizon and far-field regime solutions, we solve analytically the corresponding field equations of motion. From this, we derive analytical results for the absorption probabilities and Hawking radiation emission rates, in the low-energy and low-rotation case, for both species of fields. We produce plots of these, comparing them to existing exact numerical results with very good agreement. We also study the total absorption cross-section and demonstrate that, as in the non-rotating case, it has a different behaviour for fermions and gauge bosons in the low-energy limit, while it follows a universal behaviour -- reaching a constant, spin-independent, asymptotic value -- in the high-energy regime.Comment: 22 pages, 8 figures, added reference

Greybody Factors for Brane Scalar Fields in a Rotating Black-Hole Background

We study the evaporation of (4+n)-dimensional rotating black holes into scalar degrees of freedom on the brane. We calculate the corresponding absorption probabilities and cross-sections obtaining analytic solutions in the low-energy regime, and compare the derived analytic expressions to numerical results, with very good agreement. We then consider the high-energy regime, construct an analytic high-energy solution to the scalar-field equation by employing a new method, and calculate the absorption probability and cross-section for this energy regime, finding again a very good agreement with the exact numerical results. We also determine the high-energy asymptotic value of the total cross-section, and compare it to the analytic results derived from the application of the geometrical optics limit.Comment: Latex file, 30 pages, 5 figures, typos corrected, version published in Phys. Rev.

Lung function, coronary artery calcification, and metabolic syndrome in 4905 Korean males

SummaryBackgroundImpaired lung function is an independent predictor of cardiovascular mortality. We assessed the relationships of lung function with insulin resistance (IR), metabolic syndrome (MetS), systemic inflammation and coronary artery calcification score (CACS) measured by computed tomography (CT) scan an indicator of coronary atherosclerosis.MethodsWe identified 4905 adult male patients of the Health Promotion Center in Samsung Medical Center between March 2005 and February 2008 and retrospectively reviewed the following data for these patients: pulmonary function, CT-measured CACS, anthropometric measurement, fasting glucose, insulin, lipid profiles, serum C-reactive protein (CRP) and homeostatic model assessment (HOMA-IR). MetS was defined according to the AHA/NHLBI criteria.ResultsWhen the subjects were divided into four groups according to quartiles of FVC or FEV1 (% pred), serum CRP level, HOMA-IR, prevalence of MetS and CACS significantly increased as the FVC or FEV1 (% pred) decreased. The odds ratios (ORs) for MetS in the lowest quartiles of FVC and FEV1 (% pred) were 1.85 (95% CI, 1.49–2.30; p<0.001) and 1.47 (95% CI, 1.20–1.81; p<0.001) respectively. The ORs for the presence of coronary artery calcification in the lowest quartiles of FVC and FEV1 (% pred) were 1.31 (95% CI, 1.09–1.58; p=0.004) and 1.22 (95% CI, 1.02–1.46; p=0.029) respectively. Obesity, CRP, HOMA-IR, and the presence of coronary artery calcium were independent risk predictors for impaired lung function.ConclusionMetabolic syndrome, insulin resistance, coronary atherosclerosis, and systemic inflammation are closely related to the impaired lung function

Control of Anchoring of Nematic Fluids at Polymer Surfaces Created by in Situ Photopolymerization

In situ photopolymerization of alkyl acrylate monomers in the presence of a nematic fluid provides a cellular matrix of liquid crystalline droplets in which the chemical structure of the encapsulating polymer exerts control over the alignment (anchoring) of the liquid crystalline molecules. Control is obtained by variation of the alkyl side chains and through copolymerization of two dissimilar monofunctional acrylates. For example, among a series of poly(methylheptyl acrylate)s, the 1-methylheptyl analogue prefers planar anchoring of a nematic (TL205) over the temperature range studied. However, the polymers of other methylheptyl side chains display a homeotropic-to-planar anchoring thermal transition temperature similar to that of the n-heptyl analogue. Copolymerization of two monofunctional acrylates with opposing tendencies of aligning liquid crystal leads to tunability of anchoring behavior over a wide temperature range. The broad anchoring transitions we observed provide a way of achieving highly tilted anchoring