Uniform approximation of homeomorphisms by diffeomorphisms

We prove that a compactly supported homeomorphism of a smooth manifold of dimension greater or equal to 5 can be approximated uniformly by compactly supported diffeomorphisms if and only if it is isotopic to a diffeomorphism. If the given homeomorphism is in addition volume preserving, then it can be approximated uniformly by volume preserving diffeomorphisms.Comment: v4: 5 pages; long overdue revision; clarified and improved statements, notation, and proofs. The main theorem may already be known, but I have not been able to find a precise reference. After talking to a number of topologists without getting a satisfactory answer, I decided to write up the proof myself. Comments and references welcom

Charmonium - Pion Cross Section from QCD Sum Rules

The $J/\psi \pi\to \bar{D} D^*, \bar{D} D$, ${\bar D}^* D^*$ and ${\bar D} D^*$ cross sections as a function of $\sqrt{s}$ are evaluated in a QCD sum rule calculation. We study the Borel sum rule for the four point function involving pseudoscalar and vector meson currents, up to dimension four in the operator product expansion. We find that our results are smaller than the $J/\psi \pi\to {charmed mesons}$ cross sections obtained with models based on meson exchange, but are close to those obtained with quark exchange models.Comment: revised version accepted for publication in Phys. Lett.

Investigating the evolution of the dual AGN system ESO~509-IG066

We analyze the evolution of the dual AGN in ESO 509-IG066, a galaxy pair located at z=0.034 whose nuclei are separated by 11 kpc. Previous observations with XMM-Newton on this dual AGN found evidence for two moderately obscured ($N_H\sim10^{22}$ cm$^{-2}$) X-ray luminous ($L_X\sim10^{43}$ erg/s) nuclear sources. We present an analysis of subsequent Chandra, NuSTAR and Swift/XRT observations that show one source has dropped in flux by a factor of 10 between 2004 and 2011, which could be explained by either an increase in the absorbing column or an intrinsic fading of the central engine possibly due to a decrease in mass accretion. Both of these scenarios are predicted by galaxy merger simulations. The source which has dropped in flux is not detected by NuSTAR, which argues against absorption, unless it is extreme. However, new Keck/LRIS optical spectroscopy reveals a previously unreported broad H-alpha line which is highly unlikely to be visible under the extreme absorption scenario. We therefore conclude that the black hole in this nucleus has undergone a dramatic drop in accretion rate. From AO-assisted near-infrared integral-field spectroscopy of the other nucleus, we find evidence that the galaxy merger is having a direct effect on the kinematics of the gas close to the nucleus of the galaxy, providing a direct observational link between the galaxy merger and the mass accretion rate on to the black hole.Comment: Accepted for publication in Ap

An ATP-binding cassette-type cysteine transporter in Campylobacter jejuni inferred from the structure of an extracytoplasmic solute receptor protein

Campylobacter jejuni is a Gram-negative food-borne pathogen associated with gastroenteritis in humans as well as cases of the autoimmune disease Guillain Barre syndrome. C. jejuni is asaccharolytic because it lacks an active glycolytic pathway for the use of sugars as a carbon source. This suggests an increased reliance on amino acids as nutrients and indeed the genome sequence of this organism indicates the presence of a number of amino acid uptake systems. Cj0982, also known as CjaA, is a putative extracytoplasmic solute receptor for one such uptake system as well as a major surface antigen and vaccine candidate. The crystal structure of Cj0982 reveals a two-domain protein with density in the enclosed cavity between the domains that clearly defines the presence of a bound cysteine ligand. Fluorescence titration experiments were used to demonstrate that Cj0982 binds cysteine tightly and specifically with a K-d of similar to 10(-7) M consistent with a role as a receptor for a high- affinity transporter. These data imply that Cj0982 is the binding protein component of an ABC-type cysteine transporter system and that cysteine uptake is important in the physiology of C. jejuni

A false-discovery-rate-based loss framework for selection of interactions

Interaction effects have been consistently found important in explaining the variation in outcomes in many scientific research fields. Yet, in practice, variable selection including interactions is complicated due to the limited sample size, conflicting philosophies regarding model interpretability, and accompanying amplified multiple-testing problems. The lack of statistically sound algorithms for automatic variable selection with interactions has discouraged activities in exploring important interaction effects. In this article, we investigated issues of selecting interactions from three aspects: (1) What is the model space to be searched? (2) How is the hypothesis-testing performed? (3) How to address the multiple-testing issue? We propose loss functions and corresponding decision rules that control FDR in a Bayesian context. Properties of the decision rules are discussed and their performance in terms of power and FDR is compared through simulations. Methods are illustrated on data from a colorectal cancer study assessing the chemotherapy treatments and data from a diffuse large-B-cell lymphoma study assessing the prognostic effect of gene expressions. Copyright © 2007 John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58564/1/3118_ftp.pd

The subconvexity problem for \GL_{2}

Generalizing and unifying prior results, we solve the subconvexity problem for the $L$-functions of \GL_{1} and \GL_{2} automorphic representations over a fixed number field, uniformly in all aspects. A novel feature of the present method is the softness of our arguments; this is largely due to a consistent use of canonically normalized period relations, such as those supplied by the work of Waldspurger and Ichino--Ikeda.Comment: Almost final version to appear in Publ. Math IHES. References updated

Flow boiling heat transfer of R134a and low GWP refrigerants in a horizontal micro-scale channel

The present paper presents an investigation of the effects of the refrigerant type on the heat transfer coefficient during flow boiling inside micro-scale channels. Experimental results for R134a, R1234ze(E), R1234yf and R600a for flow boiling in a circular channel with internal diameter of 1.1 mm are presented. The experimental database comprises 3409 data points covering mass velocities ranging from 200 to 800 kg/m²s, heat fluxes from 15 to 145 kW/m², saturation temperatures of 31 and 41°C, and vapor qualities from 0.05 to 0.95. The experimental data were parametrically analysed and the effects of the experimental parameters (heat flux, mass velocity, saturation temperature and working fluid) identified. Subsequently, the experimental data were compared against the most quoted predictive methods from literature, including macro and micro-scale methods. Based on the broad database obtained in the present study, an updated version of the predictive method of Kanizawa et al. [1] was proposed. The updated version provided accurate predictions of the present experimental database, predicting more than 97% and 86% of the results within error bands of ±30 and ±20%, respectively.The authors gratefully acknowledge FAPESP (The State of São Paulo Research Foundation, Brazil) for the financial support under contract numbers 2010/17605-4 and 2011/50176-2 and CNPq (The National Council for Scientific and Technological Development, Brazil) for the financial support under Contract Numbers nº476763/2013-4 and 303852/2013-5. The technical support given to this investigation by Mr. José Roberto Bogni is also appreciated and deeply recognized. The authors are also grateful to Honeywell for supplying the low GWP refrigerants R1234ze(E) and R1234yf

Introduction to Quantum Algorithms for Physics and Chemistry

In this introductory review, we focus on applications of quantum computation to problems of interest in physics and chemistry. We describe quantum simulation algorithms that have been developed for electronic-structure problems, thermal-state preparation, simulation of time dynamics, adiabatic quantum simulation, and density functional theory.Comment: 44 pages, 5 figures; comments or suggestions for improvement are welcom