A new interpretation of dielectric data in molecular glass formers

Literature dielectric data of glycerol, propylene carbonate and ortho-terphenyl (OTP) show that the measured dielectric relaxation is a decade faster than the Debye expectation, but still a decade slower than the breakdown of the shear modulus. From a comparison of time scales, the dielectric relaxation seems to be due to a process which relaxes not only the molecular orientation, but the entropy, the short-range order and the density as well. On the basis of this finding, we propose an alternative to the Gemant-DiMarzio-Bishop extension of the Debye picture.Comment: 7 pages, 4 figures, 68 references; 3. version extended following referee advic

Crystal structure, incommensurate magnetic order and ferroelectricity in mn1−x_{1-x}cux_{x}wo4{_4} (x=0-0.19)

We have carried out a systematic study on the effect of Cu doping on nuclear, magnetic, and dielectric properties in Mn$_{1-x}$Cu$_{x}$WO$_4$ for ${0}\leq{x}\leq{0.19}$ by a synergic use of different techniques, viz, heat capacity, magnetization, dielectric, and neutron powder diffraction measurements. Via heat capacity and magnetization measurements we show that with increasing Cu concentration magnetic frustration decreases, which leads to the stabilization of commensurate magnetic ordering. This was further verified by temperature-dependent unit cell volume changes derived from neutron diffraction measurements which was modeled by the Gr\"{u}neisen approximation. Dielectric measurements show a low temperature phase transition below about 9-10 K. Further more, magnetic refinements reveal no changes below this transition indicating a possible spin-flop transition which is unique to the Cu doped system. From these combined studies we have constructed a magnetoelectric phase diagram of this compound.Comment: 9 pages, 9 figures, accepted for publication in PR

Minimal Gauge Invariant Classes of Tree Diagrams in Gauge Theories

We describe the explicit construction of groves, the smallest gauge invariant classes of tree Feynman diagrams in gauge theories. The construction is valid for gauge theories with any number of group factors which may be mixed. It requires no summation over a complete gauge group multiplet of external matter fields. The method is therefore suitable for defining gauge invariant classes of Feynman diagrams for processes with many observed final state particles in the standard model and its extensions.Comment: 13 pages, RevTeX (EPS figures

D-Meson Mixing in Broken SU(3)

A fit of amplitudes to the experimental branching ratios to two mesons is used to construct a new estimate of neutral $D$ mixing which includes $SU(3)$ breaking. The result is dominated by the experimental uncertainties. This suggests that the charm sector may not be as sensitive to new physics as previously thought and that long-distance calculations may not be useful.Comment: 12 pages, LaTeX, no figure

Birth and growth of cavitation bubbles within water under tension confined in a simple synthetic tree

Water under tension, as can be found in several systems including tree vessels, is metastable. Cavitation can spontaneously occur, nucleating a bubble. We investigate the dynamics of spon- taneous or triggered cavitation inside water filled microcavities of a hydrogel. Results show that a stable bubble is created in only a microsecond timescale, after transient oscillations. Then, a diffusion driven expansion leads to filling of the cavity. Analysis reveals that the nucleation of a bubble releases a tension of several tens of MPa, and a simple model captures the different time scales of the expansion process

Ethnicity and age as factors in sildenafil treatment of erectile dysfunction

IntroductionSildenafil has been evaluated in >16 000 men with erectile dysfunction (ED) in doubleâ blind, placeboâ controlled trials.AimTo assess efficacy and safety of sildenafil in ED by ethnicity (white, black Asian) and age (â ¤45, 46â 60, â ¥61 years).MethodsData were pooled from 38 doubleâ blind, placeboâ controlled, flexibleâ dose trials. Most had starting sildenafil doses of 50 mg once daily, ~1 hour before sexual activity, with adjustment to 100 or 25 mg as needed.Main Outcome MeasuresChange from baseline in International Index of Erectile Function erectile function (IIEFâ EF) domain score assessed with analysis of covariance and a Global Assessment Question (GAQ; â Did the treatment improve your erections?â ) at endpoint assessed with logistic regression analysis.Results4120 and 3714 men received sildenafil and placebo, respectively (2740 and 2671 White; 407 and 385 Black; 973 and 658 Asian). For sildenafil vs. placebo groups, overall treatment differences for IIEFâ EF domain and GAQ were significant for each ethnic and age group (P<.0001); significant treatmentâ byâ ethnicity and treatmentâ byâ age interactions were also observed for change in IIEFâ EF domain scores (P<.05), with differences significantly greater for White vs. Black (P<.0001), White vs. Asian (P=.0163), and Asian vs. Black (P=.0036) men. A significant treatmentâ byâ ethnicity interaction was observed for GAQ (P=.0004). The OR comparison for GAQ was significantly greater (P=.0001) with sildenafil vs. placebo in White (OR=11.2) or Asian (OR=12.4) men vs. Black men (OR=5.1). Adverseâ event rates were generally similar, with some age variations.ConclusionsSildenafil is effective and wellâ tolerated regardless of ethnicity or age; however, treatment effects can vary.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/137386/1/ijcp12945_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/137386/2/ijcp12945.pd

A Completely Invariant SUSY Transform of Supersymmetric QED

We study the SUSY breaking of the covariant gauge-fixing term in SUSY QED and observe that this corresponds to a breaking of the Lorentz gauge condition by SUSY. Reasoning by analogy with SUSY's violation of the Wess-Zumino gauge, we argue that the SUSY transformation, already modified to preserve Wess-Zumino gauge, should be further modified by another gauge transformation which restores the Lorentz gauge condition. We derive this modification and use the resulting transformation to derive a Ward identitiy relating the photon and photino propagators without using ghost fields. Our transformation also fulfills the SUSY algebra, modulo terms that vanish in Lorentz gauge

Spacetime Noncommutativity in Models with Warped Extradimensions

We construct consistent noncommutative (NC) deformations of the Randall-Sundrum spacetime that solve the NC Einstein equations with a non-trivial Poisson tensor depending on the fifth coordinate. In a class of these deformations where the Poisson tensor is exponentially localized on one of the branes (the NC-brane), we study the effects on bulk particles in terms of Lorentz-violating operators induced by NC-brane interactions. We sketch two models in which massive bulk particles mediate NC effects to an almost-commutative SM-brane, such that observables at high energy colliders are enhanced with respect to low energy and astrophysical observables.Comment: 15 pages, LaTeX, pdf figures included, to appear in JHE

Pupil Alignment Considerations for Large, Deployable Space Telescopes

For many optical systems the properties and alignment of the internal apertures and pupils are not critical or controlled with high precision during optical system design, fabrication or assembly. In wide angle imaging systems, for instance, the entrance pupil position and orientation is typically unconstrained and varies over the system s field of view in order to optimize image quality. Aperture tolerances usually do not receive the same amount of scrutiny as optical surface aberrations or throughput characteristics because performance degradation is typically graceful with misalignment, generally only causing a slight reduction in system sensitivity due to vignetting. But for a large deployable space-based observatory like the James Webb Space Telescope (JWST), we have found that pupil alignment is a key parameter. For in addition to vignetting, JWST pupil errors cause uncertainty in the wavefront sensing process that is used to construct the observatory on-orbit. Furthermore they also open stray light paths that degrade the science return from some of the telescope s instrument channels. In response to these consequences, we have developed several pupil measurement techniques for the cryogenic vacuum test where JWST science instrument pupil alignment is verified. These approaches use pupil alignment references within the JWST science instruments; pupil imaging lenses in three science instrument channels; and unique pupil characterization features in the optical test equipment. This will allow us to verify and crosscheck the lateral pupil alignment of the JWST science instruments to approximately 1-2% of their pupil diameters