On the Dynamics of Light Quarks in QCD

We describe recent results concerning the behavior of lattice QCD with light dynamical Wilson and Staggered quarks. We show that it is possible to reach regions of parameter space with light pions $m_\pi\approx 0.2/a$ using Wilson fermions. If the Hybrid Molecular Dynamics (HMD) algorithm is used with the same parameters it gives incorrect results. We also present preliminary results using a higher-order integration scheme.Comment: 4 pages (all in postscript), proceedings of LAT'9

A polymer coated cicaprost-eluting stent increases neointima formation and impairs vessel function in the rabbit iliac artery

Drug-eluting stents have been successful in reducing in-stent restenosis but are not suitable for all lesion types and have been implicated in causing late stent thrombosis due to incomplete regeneration of the endothelial cell layer. In this study we implanted stents coated with cicaprost, a prostacyclin analogue with a long plasma half-life and antiproliferative effects on vascular smooth muscle cells, into the iliac arteries of rabbits. At 28-day follow-up we compared neointima formation within the stented vessels and vascular function in adjacent vessels, to assess if cicaprost could reduce restenosis without impairing vessel function. Arteries implanted with cicaprost eluting stents had significantly more neointima compared to bare metal stents. In adjacent segments of artery, endothelium-dependent relaxation was impaired by the cicaprost-eluting stent but vasodilation to an endothelium-independent vasodilator was maintained. We conclude that the presence of the polymer and sub-optimal release of cicaprost from the stent may be responsible for the increased neointma and impaired functional recovery of the endothelium observed. Further experiments should be aimed at optimising release of cicaprost and exploring different stent polymer coatings

Characterisation of P2Y2 receptors in human vascular endothelial cells using AR-C118925XX, a competitive and selective P2Y2 antagonist

Background and Purpose: There is a lack of potent, selective antagonists at most subtypes of P2Y receptor. The aims of this study were to characterise the pharmacological properties of the proposed P2Y 2 receptor antagonist, AR-C118925XX, and then to use it to determine the role of P2Y 2 receptors in the action of the P2Y 2 agonist, UTP, in human vascular endothelial cells. Experimental Approach: Cell lines expressing native or recombinant P2Y receptors were superfused constantly, and agonist-induced changes in intracellular Ca 2+ levels monitored using the Ca 2+-sensitive fluorescent indicator, Cal-520. This set-up enabled full agonist concentration–response curves to be constructed on a single population of cells. Key Results: UTP evoked a concentration-dependent rise in intracellular Ca 2+ in 1321N1-hP2Y 2 cells. AR-C118925XX (10 nM to 1 μM) had no effect per se on intracellular Ca 2+ but shifted the UTP concentration–response curve progressively rightwards, with no change in maximum. The inhibition was fully reversible on washout. AR-C118925XX (1 μM) had no effect at native or recombinant hP2Y 1, hP2Y 4, rP2Y 6, or hP2Y 11 receptors. Finally, in EAhy926 immortalised human vascular endothelial cells, AR-C118925XX (30 nM) shifted the UTP concentration–response curve rightwards, with no decrease in maximum. Conclusions and Implications: AR-C118925XX is a potent, selective and reversible, competitive P2Y 2 receptor antagonist, which inhibited responses mediated by endogenous P2Y 2 receptors in human vascular endothelial cells. As the only P2Y 2-selective antagonist currently available, it will greatly enhance our ability to identify the functions of native P2Y 2 receptors and their contribution to disease and dysfunction

Duration and exposure to virtual environments: Sickness curves during and across sessions

Although simulator sickness is known to increase with protracted exposure and to diminish with repeated sessions, limited systematic research has been performed in these areas. This study reviewed the few studies with sufficient information available to determine the effect-that exposure duration and repeated exposure have on motion sickness. This evaluation confirmed that longer exposures produce more symptoms and that total sickness subsides over repeated exposures. Additional evaluation was performed to investigate the precise form of this relationship and to determine whether the same form was generalizable across varied simulator environments. The results indicated that exposure duration and repeated exposures are significantly linearly related to sickness outcomes (duration being positively related and repetition negatively related to total sickness). This was true over diverse systems and large subject pools. This result verified the generalizability of-the relationships among sickness, exposure duration, and repeated exposures. Additional research is indicated to determine the optimal length of a single exposure and the optimal intersession interval to facilitate adaptation

Foliar physiognomic record of climatic conditions during dormancy: Climate Leaf Analysis Multivariate Program (CLAMP) and the cold month mean temperature

The extent to which the leaves of woody dicots encode in their physiognomy the climatic conditions that exist during dormancy was tested by sampling 20 sites along an approximately west-east transect across European Russia, the Crimean Peninsula, Western Siberia, and central Eastern Siberia. This transect encompassed the most extreme mean annual temperature range recorded in the modern world where vegetation exists. Climate Leaf Analysis Multivariate Program (CLAMP) revealed little change in calibration of the warm month mean temperature compared with the PHYSG3AR data set derived from less extreme sites primarily in North America and Japan, but significant change with respect to the cold month mean temperature (CMMT) calibration. Although CLAMP underestimated the CMMT by up to 9°C in the coldest sites, the addition of the transect sites improved CLAMP's performance at low temperatures. This suggests that winter cold is encoded in foliar physiognomy even though the leaves are functional only during the late spring and summer months. This increase in performance was, however, at the cost of decreasing precision. Precipitation predictive capabilities were only slightly affected, but calibration of key climatic variables such as enthalpy, used in determining palaeoaltitude, remained more or less unchanged after the inclusion of the cold transect samples. © 2004 by The University of Chicago. All rights reseved

Toward systematic control of cybersickness

Visually induced motion sickness, or cybersickness, has been well documented in all kinds of vehicular simulators and in many virtual environments. It probably occurs in all virtual environments. Cybersickness has many known determinants, including (a short list) field-of-view, flicker, transport delays, duration of exposure, gender, and susceptibility to motion sickness. Since many of these determinants can be controlled, a major objective in designing virtual environments is to hold cybersickness below a specified level a specified proportion of the time. More than 20 years ago C. W. Simon presented a research strategy based on fractional factorial experiments that was capable in principle of realizing this objective. With one notable exception, however, this strategy was not adopted by the human factors community. The main reason was that implementing Simon\u27s strategy was a major undertaking, very time-consuming, and very costly. In addition, many investigators were not satisfied that Simon had adequately addressed issues of statistical reliability. The present paper proposes a modified Simonian approach to the sate objective (holding cybersickness below specified standards) with some loss in the range of application but a greatly reduced commitment of resources