Unquenching the Quark Model and Screened Potentials

The low-lying spectrum of the quark model is shown to be robust under the effects of `unquenching'. In contrast, the use of screened potentials is shown to be of limited use in models of hadrons. Applications to unquenching the lattice Wilson loop potential and to glueball mixing in the adiabatic hybrid spectrum are also presented.Comment: 6 pages, 3 ps figures, revtex. Version to appear in J. Phys.

The Emergence of the Modern Universe: Tracing the Cosmic Web

This is the report of the Ultraviolet-Optical Working Group (UVOWG) commissioned by NASA to study the scientific rationale for new missions in ultraviolet/optical space astronomy approximately ten years from now, when the Hubble Space Telescope (HST) is de-orbited. The UVOWG focused on a scientific theme, The Emergence of the Modern Universe, the period from redshifts z = 3 to 0, occupying over 80% of cosmic time and beginning after the first galaxies, quasars, and stars emerged into their present form. We considered high-throughput UV spectroscopy (10-50x throughput of HST/COS) and wide-field optical imaging (at least 10 arcmin square). The exciting science to be addressed in the post-HST era includes studies of dark matter and baryons, the origin and evolution of the elements, and the major construction phase of galaxies and quasars. Key unanswered questions include: Where is the rest of the unseen universe? What is the interplay of the dark and luminous universe? How did the IGM collapse to form the galaxies and clusters? When were galaxies, clusters, and stellar populations assembled into their current form? What is the history of star formation and chemical evolution? Are massive black holes a natural part of most galaxies? A large-aperture UV/O telescope in space (ST-2010) will provide a major facility in the 21st century for solving these scientific problems. The UVOWG recommends that the first mission be a 4m aperture, SIRTF-class mission that focuses on UV spectroscopy and wide-field imaging. In the coming decade, NASA should investigate the feasibility of an 8m telescope, by 2010, with deployable optics similar to NGST. No high-throughput UV/Optical mission will be possible without significant NASA investments in technology, including UV detectors, gratings, mirrors, and imagers.Comment: Report of UV/O Working Group to NASA, 72 pages, 13 figures, Full document with postscript figures available at http://casa.colorado.edu/~uvconf/UVOWG.htm

A randomized controlled trial of an online, compassion-based intervention for maternal psychological well-being in the first year postpartum

Objectives New self-help interventions have been called for to promote psychological well-being amongst mothers in the first year postpartum, with compassion-based interventions having potential in this regard. The present study developed and evaluated a low-intensity, online, compassion-based intervention for this population called Kindness for Mums Online (KFMO). Methods UK mothers of infants under one year (N = 206) participated in a pragmatic randomized controlled trial, comparing KFMO with a waitlist control. Results The effect of the intervention on well-being (the primary outcome) was small and was sensitive to the way missing data were treated. However, KFMO robustly increased self-compassion relative to control, from baseline (week 0) to post-intervention (week 6), and from baseline to follow-up (week 12). No effects were observed on other secondary outcomes. Conclusions The findings suggest that self-compassion can be increased in postpartum mothers via an accessible, low-intensity, web-based, self-help program. However, this did not translate into robust improvements in well-being. Study limitations include relatively high attrition rates and limited generalizability to more diverse samples

Far-Ultraviolet Color Gradients in Early-Type Galaxies

We discuss far-UV (1500 A) surface photometry and FUV-B color profiles for 8 E/S0 galaxies from images taken with the Ultraviolet Imaging Telescope, primarily during the Astro-2 mission. In three cases, the FUV radial profiles are more consistent with an exponential than a de Vaucouleurs function, but there is no other evidence for the presence of a disk or of young, massive stars. In all cases except M32 the FUV-B color becomes redder at larger radii. There is a wide range of internal radial FUV-B color gradients. However, we find no correlation between the FUV-B color gradients and internal metallicity gradients based on Mg absorption features. We conclude that metallicity is not the sole parameter controlling the "UV upturn component" in old populations.Comment: 11 pages; tar.gz file includes LaTeX text file, 3 PostScript figures. Paper to be published in ApJ Letter

Non-perturbative Test of the Witten-Veneziano Formula from Lattice QCD

We compute both sides of the Witten-Veneziano formula using lattice techniques. For the one side we perform dedicated quenched simulations and use the spectral projector method to determine the topological susceptibility in the pure Yang-Mills theory. The other side we determine in lattice QCD with $N_f=2+1+1$ dynamical Wilson twisted mass fermions including for the first time also the flavour singlet decay constant. The Witten-Veneziano formula represents a leading order expression in the framework of chiral perturbation theory and we also employ leading order chiral perturbation theory to relate the flavor singlet decay constant to the relevant decay constant parameters in the quark flavor basis and flavor non-singlet decay constants. After taking the continuum and the SU$(2)$ chiral limits we compare both sides and find good agreement within uncertainties.Comment: 30 pages, 7 figures, version accepted for publicatio

Relative sound localisation abilities in human listeners

Spatial acuity varies with sound-source azimuth, signal-to-noise ratio, and the spectral characteristics of the sound source. Here, the spatial localisation abilities of listeners were assessed using a relative localisation task. This task tested localisation ability at fixed angular separations throughout space using a two-alternative forced-choice design across a variety of listening conditions. Subjects were required to determine whether a target sound originated to the left or right of a preceding reference in the presence of a multi-source noise background. Experiment 1 demonstrated that subjects' ability to determine the relative location of two sources declined with less favourable signal-to-noise ratios and at peripheral locations. Experiment 2 assessed performance with both broadband and spectrally restricted stimuli designed to limit localisation cues to predominantly interaural level differences or interaural timing differences (ITDs). Predictions generated from topographic, modified topographic, and two-channel models of sound localisation suggest that for low-pass stimuli, where ITD cues were dominant, the two-channel model provides an adequate description of the experimental data, whereas for broadband and high frequency bandpass stimuli none of the models was able to fully account for performance. Experiment 3 demonstrated that relative localisation performance was uninfluenced by shifts in gaze direction

Quasi-Homogeneous Thermodynamics and Black Holes

We propose a generalized thermodynamics in which quasi-homogeneity of the thermodynamic potentials plays a fundamental role. This thermodynamic formalism arises from a generalization of the approach presented in paper [1], and it is based on the requirement that quasi-homogeneity is a non-trivial symmetry for the Pfaffian form $\delta Q_{rev}$. It is shown that quasi-homogeneous thermodynamics fits the thermodynamic features of at least some self-gravitating systems. We analyze how quasi-homogeneous thermodynamics is suggested by black hole thermodynamics. Then, some existing results involving self-gravitating systems are also shortly discussed in the light of this thermodynamic framework. The consequences of the lack of extensivity are also recalled. We show that generalized Gibbs-Duhem equations arise as a consequence of quasi-homogeneity of the thermodynamic potentials. An heuristic link between this generalized thermodynamic formalism and the thermodynamic limit is also discussed.Comment: 39 pages, uses RevteX. Published version (minor changes w.r.t. the original one

The GALEX UV luminosity function of the cluster of galaxies Abell 1367

We present the GALEX NUV (2310 A) and FUV (1530 A) galaxy luminosity functions of the nearby cluster of galaxies A1367 in the magnitude range -20.3< M_AB < -13.3. The luminosity functions are consistent with previous (~ 2 mag shallower) estimates based on the FOCA and FAUST experiments, but display a steeper faint-end slope than the GALEX luminosity function for local field galaxies. Using spectro-photometric optical data we select out star-forming systems from quiescent galaxies and study their separate contributions to the cluster luminosity function. We find that the UV luminosity function of cluster star-forming galaxies is consistent with the field. The difference between the cluster and field LF is entirely due to the contribution at low luminosities (M_AB >-16 mag) of non star-forming, early-type galaxies that are significantly over dense in clusters.Comment: 4 pages, 4 figures, 1 table. Accepted for publication in Astrophysical Journal Letter

Optical Scattering Lengths in Large Liquid-Scintillator Neutrino Detectors

For liquid-scintillator neutrino detectors of kiloton scale, the transparency of the organic solvent is of central importance. The present paper reports on laboratory measurements of the optical scattering lengths of the organic solvents PXE, LAB, and Dodecane which are under discussion for next-generation experiments like SNO+, Hanohano, or LENA. Results comprise the wavelength range from 415 to 440nm. The contributions from Rayleigh and Mie scattering as well as from absorption/re-emission processes are discussed. Based on the present results, LAB seems to be the preferred solvent for a large-volume detector.Comment: 9 pages, 3 figures, accepted for publication by Rev. Scient. Instr