A systematic review of neuroprotective strategies after cardiac arrest: from bench to bedside (Part I - Protection via specific pathways).

Neurocognitive deficits are a major source of morbidity in survivors of cardiac arrest. Treatment options that could be implemented either during cardiopulmonary resuscitation or after return of spontaneous circulation to improve these neurological deficits are limited. We conducted a literature review of treatment protocols designed to evaluate neurologic outcome and survival following cardiac arrest with associated global cerebral ischemia. The search was limited to investigational therapies that were utilized to treat global cerebral ischemia associated with cardiac arrest. In this review we discuss potential mechanisms of neurologic protection following cardiac arrest including actions of several medical gases such as xenon, argon, and nitric oxide. The 3 included mechanisms are: 1. Modulation of neuronal cell death; 2. Alteration of oxygen free radicals; and 3. Improving cerebral hemodynamics. Only a few approaches have been evaluated in limited fashion in cardiac arrest patients and results show inconclusive neuroprotective effects. Future research focusing on combined neuroprotective strategies that target multiple pathways are compelling in the setting of global brain ischemia resulting from cardiac arrest

Diffusive behavior of a greedy traveling salesman

Using Monte Carlo simulations we examine the diffusive properties of the greedy algorithm in the d-dimensional traveling salesman problem. Our results show that for d=3 and 4 the average squared distance from the origin is proportional to the number of steps t. In the d=2 case such a scaling is modified with some logarithmic corrections, which might suggest that d=2 is the critical dimension of the problem. The distribution of lengths also shows marked differences between d=2 and d>2 versions. A simple strategy adopted by the salesman might resemble strategies chosen by some foraging and hunting animals, for which anomalous diffusive behavior has recently been reported and interpreted in terms of Levy flights. Our results suggest that broad and Levy-like distributions in such systems might appear due to dimension-dependent properties of a search space.Comment: accepted in Phys. Rev.

Timing of the 2008 Outburst of SAX J1808.4-3658 with XMM-Newton: A Stable Orbital Period Derivative over Ten Years

We report on a timing analysis performed on a 62-ks long XMM-Newton observation of the accreting millisecond pulsar SAX J1808.4-3658 during the latest X-ray outburst that started on September 21, 2008. By connecting the time of arrivals of the pulses observed during the XMM observation, we derived the best-fit orbital solution and a best-fit value of the spin period for the 2008 outburst. Comparing this new set of orbital parameters and, in particular, the value of the time of ascending-node passage with the orbital parameters derived for the previous four X-ray outbursts of SAX J1808.4-3658 observed by the PCA on board RXTE, we find an updated value of the orbital period derivative, which turns out to be $\dot P_{\rm orb} = (3.89 \pm 0.15) \times 10^{-12}$ s/s. This new value of the orbital period derivative agrees with the previously reported value, demonstrating that the orbital period derivative in this source has remained stable over the past ten years. Although this timespan is not sufficient yet for confirming the secular evolution of the system, we again propose an explanation of this behavior in terms of a highly non-conservative mass transfer in this system, where the accreted mass (as derived from the X-ray luminosity during outbursts) accounts for a mere 1% of the mass lost by the companion.Comment: 4 pages, 3 figures. Final version, including editing corrections, to appear on A&A Letter

Relationships among food label use, motivation, and dietary quality.

Nutrition information on packaged foods supplies information that aids consumers in meeting the recommendations put forth in the US Dietary Guidelines for Americans such as reducing intake of solid fats and added sugars. It is important to understand how food label use is related to dietary intake. However, prior work is based only on self-reported use of food labels, making it unclear if subjective assessments are biased toward motivational influences. We assessed food label use using both self-reported and objective measures, the stage of change, and dietary quality in a sample of 392 stratified by income. Self-reported food label use was assessed using a questionnaire. Objective use was assessed using a mock shopping task in which participants viewed food labels and decided which foods to purchase. Eye movements were monitored to assess attention to nutrition information on the food labels. Individuals paid attention to nutrition information when selecting foods to buy. Self-reported and objective measures of label use showed some overlap with each other (r=0.29, p<0.001), and both predicted dietary quality (p<0.001 for both). The stage of change diminished the predictive power of subjective (p<0.09), but not objective (p<0.01), food label use. These data show both self-reported and objective measures of food label use are positively associated with dietary quality. However, self-reported measures appear to capture a greater motivational component of food label use than do more objective measures

Misunderstanding of Front-Of-Package Nutrition Information on US Food Products.

Front-of-package nutrition symbols (FOPs) are presumably readily noticeable and require minimal prior nutrition knowledge to use. Although there is evidence to support this notion, few studies have focused on Facts Up Front type symbols which are used in the US. Participants with varying levels of prior knowledge were asked to view two products and decide which was more healthful. FOPs on packages were manipulated so that one product was more healthful, allowing us to assess accuracy. Attention to nutrition information was assessed via eye tracking to determine what if any FOP information was used to make their decisions. Results showed that accuracy was below chance on half of the comparisons despite consulting FOPs. Negative correlations between attention to calories, fat, and sodium and accuracy indicated that consumers over-relied on these nutrients. Although relatively little attention was allocated to fiber and sugar, associations between attention and accuracy were positive. Attention to vitamin D showed no association to accuracy, indicating confusion surrounding what constitutes a meaningful change across products. Greater nutrition knowledge was associated with greater accuracy, even when less attention was paid. Individuals, particularly those with less knowledge, are misled by calorie, sodium, and fat information on FOPs

Large Scale Inhomogeneities from the QCD Phase Transition

We examine the first-order cosmological QCD phase transition for a large class of parameter values, previously considered unlikely. We find that the hadron bubbles can nucleate at very large distance scales, they can grow as detonations as well as deflagrations, and that the phase transition may be completed without reheating to the critical temperature. For a subset of the parameter values studied, the inhomogeneities generated at the QCD phase transition might have a noticeable effect on nucleosynthesis.Comment: 15 LaTeX pages + 6 PostScript figures appended at the end of the file, HU-TFT-94-1

Electroweak baryogenesis induced by a scalar field

A cosmological pseudoscalar field coupled to hypercharge topological number density can exponentially amplify hyperelectric and hypermagnetic fields while coherently rolling or oscillating, leading to the formation of a time-dependent condensate of topological number density. The topological condensate can be converted, under certain conditions, into baryons in sufficient quantity to explain the observed baryon asymmetry in the universe. The amplified hypermagnetic field can perhaps sufficiently strengthen the electroweak phase transition, and by doing so, save any pre-existing baryon number asymmetry from extinction.Comment: 8 pages, 4 figure

Star-Forming Brightest Cluster Galaxies at 0.25 < z < 1.25: A Transitioning Fuel Supply

We present a multi-wavelength study of 90 brightest cluster galaxies (BCGs) in a sample of galaxy clusters selected via the Sunyaev Zel'dovich effect by the South Pole Telescope, utilizing data from various ground- and space-based facilities. We infer the star formation rate (SFR) for the BCG in each cluster, based on the UV and IR continuum luminosity, as well as the [O II] emission line luminosity in cases where spectroscopy is available, finding 7 systems with SFR > 100 Msun/yr. We find that the BCG SFR exceeds 10 Msun/yr in 31 of 90 (34%) cases at 0.25 < z < 1.25, compared to ~1-5% at z ~ 0 from the literature. At z > 1, this fraction increases to 92(+6)(-31)%, implying a steady decrease in the BCG SFR over the past ~9 Gyr. At low-z, we find that the specific star formation rate in BCGs is declining more slowly with time than for field or cluster galaxies, most likely due to the replenishing fuel from the cooling ICM in relaxed, cool core clusters. At z > 0.6, the correlation between cluster central entropy and BCG star formation - which is well established at z ~ 0 - is not present. Instead, we find that the most star-forming BCGs at high-z are found in the cores of dynamically unrelaxed clusters. We investigate the rest-frame near-UV morphology of a subsample of the most star-forming BCGs using data from the Hubble Space Telescope, finding complex, highly asymmetric UV morphologies on scales as large as ~50-60 kpc. The high fraction of star-forming BCGs hosted in unrelaxed, non-cool core clusters at early times suggests that the dominant mode of fueling star formation in BCGs may have recently transitioned from galaxy-galaxy interactions to ICM cooling.Comment: 20 pages, 10 figures. Submitted for publication in ApJ. Comments welcom

Peaks above the Harrison-Zel'dovich spectrum due to the Quark-Gluon to Hadron Transition

The quark-gluon to hadron transition affects the evolution of cosmological perturbations. If the phase transition is first order, the sound speed vanishes during the transition, and density perturbations fall freely. This distorts the primordial Harrison-Zel'dovich spectrum of density fluctuations below the Hubble scale at the transition. Peaks are produced, which grow at most linearly in wavenumber, both for the hadron-photon-lepton fluid and for cold dark matter. For cold dark matter which is kinetically decoupled well before the QCD transition clumps of masses below $10^{-10} M_\odot$ are produced.Comment: Extended version, including evolution of density perturbations for a bag model and for a lattice QCD fit (3 new figures). Spectrum for bag model (old figure) is available in astro-ph/9611186. 9 pages RevTeX, uses epsf.sty, 3 PS figure

Effect of pre-existing baryon inhomogeneities on the dynamics of quark-hadron transition

Baryon number inhomogeneities may be generated during the epoch when the baryon asymmetry of the universe is produced, e.g. at the electroweak phase transition. The regions with excess baryon number will have a lower temperature than the background temperature of the universe. Also the value of the quark hadron transition temperature $T_c$ will be different in these regions as compared to the background region. Since a first-order quark hadron transition is very susceptible to small changes in temperature, we investigate the effect of the presence of such baryonic lumps on the dynamics of quark-hadron transition. We find that the phase transition is delayed in these lumps for significant overdensities. Consequently, we argue that baryon concentration in these regions grows by the end of the transition. We briefly discuss some models which may give rise to such high overdensities at the onset of the quark-hadron transition.Comment: 16 pages, no figures, minor changes, version to appear in Phys. Rev.