Acute effects of elevated NEFA on vascular function: a comparison of SFA and MUFA

There is emerging evidence to show that high levels of NEFA contribute to endothelial dysfunction and impaired insulin sensitivity. However, the impact of NEFA composition remains unclear. A total of ten healthy men consumed test drinks containing 50 g of palm stearin (rich in SFA) or high-oleic sunflower oil (rich in MUFA) on separate occasions; a third day included no fat as a control. The fats were emulsified into chocolate drinks and given as a bolus (approximately 10 g fat) at baseline followed by smaller amounts (approximately 3 g fat) every 30 min throughout the 6 h study day. An intravenous heparin infusion was initiated 2 h after the bolus, which resulted in a three- to fourfold increase in circulating NEFA level from baseline. Mean arterial stiffness as measured by digital volume pulse was higher during the consumption of SFA (P,0·001) but not MUFA (P¼0·089) compared with the control. Overall insulin and gastric inhibitory peptide response was greater during the consumption of both fats compared with the control (P,0·001); there was a second insulin peak in response to MUFA unlike SFA. Consumption of SFA resulted in higher levels of soluble intercellular adhesion molecule-1 (sI-CAM) at 330 min than that of MUFA or control (P#0·048). There was no effect of the test drinks on glucose, total nitrite, plasminogen activator inhibitor-1 or endothelin-1 concentrations. The present study indicates a potential negative impact of elevated NEFA derived from the consumption of SFA on arterial stiffness and sI-CAM levels. More studies are needed to fully investigate the impact of NEFA composition on risk factors for CVD

The Fundamental Surface of Quad Lenses

In a quadruply imaged lens system the angular distribution of images around the lens center is completely described by three relative angles. We show empirically that in the 3D space of these angles, spanning 180 x 180 x 90 degrees, quads from simple two-fold symmetric lenses of arbitrary radial density profile and arbitrary radially dependent ellipticity or external shear define a nearly invariant 2D surface. We give a fitting formula for the surface using SIS+elliptical lensing potential. Various circularly symmetric mass distributions with shear up to 0.4 deviate from it by typically, rms~0.1 deg, while elliptical mass distributions with ellipticity of up 0.4 deviate from it by rms~1.5 deg. The existence of a near invariant surface gives a new insight into the lensing theory and provides a framework for studying quads. It also allows one to gain information about the lens mass distribution from the image positions alone, without any recourse to mass modeling. As an illustration, we show that about 3/4 of observed galaxy-lens quads do not belong to this surface within observational error, and so require additional external shear or substructure to be modeled adequately.Comment: 24 pages, 9 figures, accepted to MNRA

Linear stability of planar premixed flames: reactive Navier-Stokes equations with finite activation energy and arbitrary Lewis number

A numerical shooting method for performing linear stability analyses of travelling waves is described and applied to the problem of freely propagating planar premixed flames. Previous linear stability analyses of premixed flames either employ high activation temperature asymptotics or have been performed numerically with finite activation temperature, but either for unit Lewis numbers (which ignores thermal-diffusive effects) or in the limit of small heat release (which ignores hydrodynamic effects). In this paper the full reactive Navier-Stokes equations are used with arbitrary values of the parameters (activation temperature, Lewis number, heat of reaction, Prandtl number), for which both thermal-diffusive and hydrodynamic effects on the instability, and their interactions, are taken into account. Comparisons are made with previous asymptotic and numerical results. For Lewis numbers very close to or above unity, for which hydrodynamic effects caused by thermal expansion are the dominant destablizing mechanism, it is shown that slowly varying flame analyses give qualitatively good but quantitatively poor predictions, and also that the stability is insensitive to the activation temperature. However, for Lewis numbers sufficiently below unity for which thermal-diffusive effects play a major role, the stability of the flame becomes very sensitive to the activation temperature. Indeed, unphysically high activation temperatures are required for the high activation temperature analysis to give quantitatively good predictions at such low Lewis numbers. It is also shown that state-insensitive viscosity has a small destabilizing effect on the cellular instability at low Lewis numbers

The Impact of NLO-Corrections on the Determination of the $\bar{u},\bar{d} Content of Nucleons from Drell-Yan Production

The interpretation of Drell-Yan production in terms of the antiquark densities depends on NLO corrections. Besides the NLO corrections to the familiar annihilation $q\bar{q}\to \gamma^* \to l^+ l^-$, there is a substantial contribution from the QCD Compton subprocesses $gq \to q\gamma^* \to q l^+ l^-$ and $g\bar{q} \to q\gamma^* \to q l^+ l^-$. The beam and target dependence of the two classes of corrections is different. We discuss the impact of this difference on the determination of the $\bar{d}-\bar{u}$ asymmetry in the proton from the comparison of the $pp$ and $pn$ Drell-Yan production.Comment: 4 pages, 1 eps-figure. To be published in Proceedings of DIS'9

Time-Domain Measurement of Broadband Coherent Cherenkov Radiation

We report on further analysis of coherent microwave Cherenkov impulses emitted via the Askaryan mechanism from high-energy electromagnetic showers produced at the Stanford Linear Accelerator Center (SLAC). In this report, the time-domain based analysis of the measurements made with a broadband (nominally 1-18 GHz) log periodic dipole array antenna is described. The theory of a transmit-receive antenna system based on time-dependent effective height operator is summarized and applied to fully characterize the measurement antenna system and to reconstruct the electric field induced via the Askaryan process. The observed radiation intensity and phase as functions of frequency were found to agree with expectations from 0.75-11.5 GHz within experimental errors on the normalized electric field magnitude and the relative phase; 0.039 microV/MHz/TeV and 17 deg, respectively. This is the first time this agreement has been observed over such a broad bandwidth, and the first measurement of the relative phase variation of an Askaryan pulse. The importance of validation of the Askaryan mechanism is significant since it is viewed as the most promising way to detect cosmogenic neutrino fluxes at E > 10^15 eV.Comment: 10 pages, 9 figures, accepted by Phys. Rev.

Experimental Research of the Diffraction and Vavilov-Cherenkov Radiation Generation in a Teflon Target

Geometry of Vavilov-Cherekov (VChR) radiation when an electron moves close to a dielectric target is in analogy to diffraction radiation (DR) geometry. In this case we may expect DR generation from the upstream face of the target besides that VChR. The joint observation of these booth types of radiation is very interesting from the pseudo-photon viewpoint, which is applicable for relativistic electrons. Unexpected results obtained in our experiment insist on reflection about nature both DR and VChR. The experiment was performed on the relativistic electron beam of the microtron of Tomsk Polytechnic University.Comment: This article will be published in Journal of Physic

Life stress and mental disorders in the South African stress and health study

Background. Although stressful life events (SLEs) are associated with psychopathology, the contribution from distal and proximal events and the specificity of their association with common mental disorders require further exploration. We examined the association of recent life events and past adversities to mood, anxiety, substance use and impulse control disorders in South Africa. Methods. Data were analysed from the South African Stress and Health study, a population-based study of mental disorders in a nationally representative sample of 4 351 adults. Psychiatric disorders were assessed with the Composite International Diagnostic Interview (CIDI). This included questions covering early and later SLEs (negative life events, relationship stress, partner violence, social strain and adverse events during childhood) and various sociodemographic variables. Logistic regression models were constructed for 3 957 respondents (2 371 female, 1 586 male) with no missing covariate data, to assess life stress and sociodemographic predictors of 12-month and lifetime disorder. Results. Recent negative life events and relationship problems were significant predictors of any 12-month disorder and any lifetime disorder. Physical partner violence predicted any lifetime disorder. There was evidence of specificity for the prediction of mood versus anxiety disorders, with childhood adversity specifically associated with mood disorders but not anxiety disorders. Single marital status was the strongest socio-demographic predictor of any 12-month and any lifetime disorder. Conclusions. Stressful life events, distal and proximal, contribute significantly and independently to the prediction of major psychiatric disorders among South Africans, underscoring the importance of screening adversities in adults with common mental disorders, and of providing appropriate adjunctive interventions

Life stress and mental disorders in the South African stress and health study

Background. Although stressful life events (SLEs) are associated with psychopathology, the contribution from distal and proximal events and the specificity of their association with common mental disorders require further exploration. We examined the association of recent life events and past adversities to mood, anxiety, substance use and impulse control disorders in South Africa. Methods. Data were analysed from the South African Stress and Health study, a population-based study of mental disorders in a nationally representative sample of 4 351 adults. Psychiatric disorders were assessed with the Composite International Diagnostic Interview (CIDI). This included questions covering early and later SLEs (negative life events, relationship stress, partner violence, social strain and adverse events during childhood) and various sociodemographic variables. Logistic regression models were constructed for 3 957 respondents (2 371 female, 1 586 male) with no missing covariate data, to assess life stress and sociodemographic predictors of 12-month and lifetime disorder. Results. Recent negative life events and relationship problems were significant predictors of any 12-month disorder and any lifetime disorder. Physical partner violence predicted any lifetime disorder. There was evidence of specificity for the prediction of mood versus anxiety disorders, with childhood adversity specifically associated with mood disorders but not anxiety disorders. Single marital status was the strongest socio-demographic predictor of any 12-month and any lifetime disorder. Conclusions. Stressful life events, distal and proximal, contribute significantly and independently to the prediction of major psychiatric disorders among South Africans, underscoring the importance of screening adversities in adults with common mental disorders, and of providing appropriate adjunctive interventions

Finite-temperature simulations of the scissors mode in Bose-Einstein condensed gases

The dynamics of a trapped Bose-condensed gas at finite temperatures is described by a generalized Gross-Pitaevskii equation for the condensate order parameter and a semi-classical kinetic equation for the thermal cloud, solved using $N$-body simulations. The two components are coupled by mean fields as well as collisional processes that transfer atoms between the two. We use this scheme to investigate scissors modes in anisotropic traps as a function of temperature. Frequency shifts and damping rates of the condensate mode are extracted, and are found to be in good agreement with recent experiments.Comment: 4 pages, 3 figure