Theory of a Continuous Hc2_{c2} Normal-to-Superconducting Transition

I study the $H_{c2}$ transition within the Ginzburg-Landau model, with $m$-component order parameter $\psi_i$. I find a renormalized fixed point free energy, exact in $m\rightarrow\infty$ limit, suggestive of a $2$nd-order transition in contrast to a general belief of a $1$st-order transition. The thermal fluctuations for $H\neq 0$ force one to consider an infinite set of marginally relevant operators for $d<d_{uc}=6$. I find $d_{lc}=4$, predicting that the ODLRO does not survive thermal fluctuations in $d=2,3$. The result is a solution to a critical fixed point that was found to be inaccessible within $\epsilon=6-d$-expansion, previously considered in E.Brezin, D.R.Nelson, A.Thiaville, Phys.Rev.B {\bf 31}, 7124 (1985), and was interpreted as a $1$st-order transition.Comment: 4 pages, self-unpacking uuencoded compressed postscript file with a figure already inside text; to appear in Phys. Rev. Lett

High temperature color conductivity at next-to-leading log order

The non-Abelian analog of electrical conductivity at high temperature has previously been known only at leading logarithmic order: that is, neglecting effects suppressed only by an inverse logarithm of the gauge coupling. We calculate the first sub-leading correction. This has immediate application to improving, to next-to-leading log order, both effective theories of non-perturbative color dynamics, and calculations of the hot electroweak baryon number violation rate.Comment: 47 pages, 6+2 figure

Self-Aligned Carbon Nanotube Yarns for Multifunctional Optoelectronic Applications

In this work, the morphology and electrocatalytic features of carbon nanotube yarns at the structural level allow for enhanced photoconversion efficiency. The energy conversion of electronhole pairs within the carbon nanotube yarn (CNY) due to the functionalization with nanostructured photoactive TiO₂ phases is remarkable. A well oriented anatase TiO₂ thin layer (approximately 100 nm) forms at the interfaces of CNY and TiO₂ mesoporous film when the sample is precoated and annealed at 350ºC. Field Emission Scanning Electron Microscopy (FESEM) images show the integrity and homogeneity of the TiO₂ surface, which is indicative of the overall durability of the CNY-based dye sensitized solar cell (DSSC); Coating TiO₂ on self-aligned carbon nanotube yarns provides several benefits from their high chemical stability, excellent functionality, nontoxicity and relatively low cost. The maximum photon to current conversion efficiency (ηAM1.5) achieved with prolonged-time stability was 3.1%

Non-perturbative dynamics of hot non-Abelian gauge fields: beyond leading log approximation

Many aspects of high-temperature gauge theories, such as the electroweak baryon number violation rate, color conductivity, and the hard gluon damping rate, have previously been understood only at leading logarithmic order (that is, neglecting effects suppressed only by an inverse logarithm of the gauge coupling). We discuss how to systematically go beyond leading logarithmic order in the analysis of physical quantities. Specifically, we extend to next-to-leading-log order (NLLO) the simple leading-log effective theory due to Bodeker that describes non-perturbative color physics in hot non-Abelian plasmas. A suitable scaling analysis is used to show that no new operators enter the effective theory at next-to-leading-log order. However, a NLLO calculation of the color conductivity is required, and we report the resulting value. Our NLLO result for the color conductivity can be trivially combined with previous numerical work by G. Moore to yield a NLLO result for the hot electroweak baryon number violation rate.Comment: 20 pages, 1 figur

Three-dimensional carbon nanotube yarn based solid state solar cells with multiple sensitizers exhibit high energy conversion efficiency

Fiber-type dye sensitized solar cells that are non-metallic, flexible, and thread-like in structure have many potential military and functional textile applications. With the use of quantum dots (QD), exciton transfer facilitators (Phenyl-C61-butyric acid methyl ester-PCBM) and Poly(3-hexylthiophene-2,5-diyl-P3HT), and careful preparation of the TiO2 oxide layer deposited on the carbon fiber working electrode, an optimized efficiency of 7.6% was obtained. Carbon nanotube yarn (CNTY) was used to prepare both the working and counter electrodes of the fabricated cells. TiCl4 annealing of the TiO2 layer was carried out and the resulting oxide layer morphology was found to be very uniform. The quantum dots, cadmium sulfide (CdS) and cadmium selenide (CdSe), were deposited directly onto the surface of the nanoporous oxide layer using chemical bath deposition (CBD). Also, the P3HT and PCBM were applied and deposited via CBD on the working electrode as a bulk heterojunction material. Potentiometric characterization of the prepared cells performed at different cell lengths and showed that the maximum efficiency was obtained for cells approximately 3.5 cm in length. Photovoltaic performance of these solid state three dimensional cells was also carried out for different cell configurations

The Impact of a 3-Year After-School Obesity Prevention Program in Elementary School Children

Children tend to be sedentary during the after-school hours, and this has deleterious effects on their health. The objective of the present study was to determine the effects of a 3-year after-school physical activity (PA) program, without restriction of dietary energy intake, on percent body fat (%BF), cardiorespiratory fitness (CRF), and cardiometabolic markers in children

Advanced cotton fibers exhibit efficient photocatalytic self-cleaning and antimicrobial activity

Functional cotton fibers have a wide range of applications in domestic, commercial, and military settings, and so enhancing the properties of these materials can yield substantial benefits. Herein, we report the creation of functional fibers that are self-cleaning, anti-microbial, and protective against UV radiation. A uniform, and high surface area films of TiO2 were deposited on cotton fibers and gold/silver nanoparticles were directly incorporated on the nanostructured TiO2 surface. The synthetic method is simple and the produced TiO2 film is homogenous and the nanoparticles were shown to be effectively distributed on the surface using a simple photocatalytic reduction method. The Ag/Au-TiO2 coated fibers was morphologically characterized using atomic force microscopy (AFM) and scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), and the self-cleaning properties of noble metal nanoparticle/TiO2 coated fibers were demonstrated by repeated staining followed by exposure to simulated solar light. The 1 mM Ag-TiO2 coated fabric was observed to have the largest improvement in rate of stain extinction compared to the untreated fibers with a methylene blue stain, and the 1 mM Au-TiO2 coated fibers were observed to have the largest improvement versus untreated fibers when stained with Congo red. The fibers maintained consistent photocatalytic activity over multiple cycles, and the resistance of the Ag/Au-TiO2 coated cotton to degradation was verified using Fourier transform infrared spectroscopy (FTIR). An efficient anti-microbial activity of the fibers was confirmed by exposure of the fibers to bacterial culture (Escherichia Coli) and direct observation of antimicrobial activity

Deformations of flows from type IIB supergravity

We consider supersymmetric SL(3,R) deformations of various type IIB supergravity backgrounds which exhibit flows away from an asymptotically locally AdS_5 x S^5 fixed point. This includes the gravity dual of the Coulomb branch of N=1 super Yang Mills theory, for which the deformed superpotential is known. We also consider the gravity duals of field theories which live on various curved backgrounds, such as Minkowski_2 x H^2, AdS_3 x S^1 and R x S^3. Some of the deformed theories flow from a four-dimensional N=1 superconformal UV fixed point to a two-dimensional (2,2) superconformal IR fixed point. We study nonsupersymmetric generalizations of the deformations of the above Coulomb branch flows.Comment: 29 pages, additional references and comment

Infra-Red Stable Supersymmetry in Chern-Simons Theories with Matter and Quenched Disorder

We study Abelian Chern-Simons field theories with matter fields and global SU(N) symmetry in the presence of random weak quenched disorder. In the absence of disorder these theories possess N=2 supersymmetric fixed points and N=1 supersymmetric fixed lines in the infra-red limit. We show that although the presence of disorder forbids any supersymmetry of the bare action, infra-red stable supersymmetric fixed points and fixed lines are realized in the disorder-averaged effective theories.Comment: 8 pp., LaTeX. Explanatory remarks and references added. Version to appear in Phys. Rev. Let