Detecting the Earliest Galaxies Through Two New Sources of 21cm Fluctuations

The first galaxies that formed at a redshift ~20-30 emitted continuum photons with energies between the Lyman-alpha and Lyman limit wavelengths of hydrogen, to which the neutral universe was transparent except at the Lyman-series resonances. As these photons redshifted or scattered into the Lyman-alpha resonance they coupled the spin temperature of the 21cm transition of hydrogen to the gas temperature, allowing it to deviate from the microwave background temperature. We show that the fluctuations in the radiation emitted by the first galaxies produced strong fluctuations in the 21cm flux before the Lyman-alpha coupling became saturated. The fluctuations were caused by biased inhomogeneities in the density of galaxies, along with Poisson fluctuations in the number of galaxies. Observing the power-spectra of these two sources would probe the number density of the earliest galaxies and the typical mass of their host dark matter halos. The enhanced amplitude of the 21cm fluctuations from the era of Lyman-alpha coupling improves considerably the practical prospects for their detection.Comment: 11 pages, 7 figures, ApJ, published. Normalization fixed in top panels of Figures 4-

Constraints on Warm Dark Matter from Cosmological Reionization

We study the constraints that high-redshift structure formation in the universe places on warm dark matter (WDM) dominated cosmological models. We modify the extended Press-Schechter formalism to derive the halo mass function in WDM models. We show that our predictions agree with recent numerical simulations at low redshift over the halo masses of interest. Applying our model to galaxy formation at high redshift, we find that the loss of power on small scales, together with the delayed collapse of low-mass objects, results in strong limits on the root-mean-square velocity dispersion v_rms of the WDM particles at z=0. For fermions decoupling while relativistic, these limits are equivalent to constraints on the mass m_X of the particles. The presence of a 4 billion solar mass black hole at z=5.8, believed to power the quasar SDSS 1044-1215, implies m_X > 0.5 keV (or v_rms < 0.10 km/s), assuming that the quasar is unlensed and radiating at or below the Eddington limit. Reionization by z=5.8 also implies a limit on m_X. If high-redshift galaxies produce ionizing photons with an efficiency similar to their z=3 counterparts, we find m_X > 1.2 keV (or v_rms < 0.03 km/s). However, given the uncertainties in current measurements from the proximity effect of the ionizing background at redshift 3, values of m_X as low as 0.75 keV (v_rms = 0.06 km/s) are not ruled out. The limit weakens further if, instead, the ionizing-photon production efficiency is greater at high z, but this limit will tighten considerably if reionization is shown in the future to have occurred at higher redshifts. WDM models with m_X 0.04 km/s) produce a low-luminosity cutoff in the high-redshift galaxy luminosity function which is directly detectable with the Next Generation Space Telescope (abridged).Comment: 38 pages, 10 figures, to appear in ApJ. One figure added, some discussion revise

Profiles of Dark Matter Velocity Anisotropy in Simulated Clusters

We report statistical results for dark matter (DM) velocity anisotropy, \beta, from a sample of some 6000 cluster-size halos (at redshift zero) identified in a \Lambda CDM hydrodynamical adaptive mesh refinement simulation performed with the Enzo code. These include profiles of \beta\ in clusters with different masses, relaxation states, and at several redshifts, modeled both as spherical and triaxial DM configurations. Specifically, although we find a large scatter in the DM velocity anisotropy profiles of different halos (across elliptical shells extending to at least ~$1.5 r_{vir}$), universal patterns are found when these are averaged over halo mass, redshift, and relaxation stage. These are characterized by a very small velocity anisotropy at the halo center, increasing outward to about 0.27 and leveling off at about $0.2 r_{vir}$. Indirect measurements of the DM velocity anisotropy fall on the upper end of the theoretically expected range. Though measured indirectly, the estimations are derived by using two different surrogate measurements - X-ray and galaxy dynamics. Current estimates of the DM velocity anisotropy are based on very small cluster sample. Increasing this sample will allow testing theoretical predictions, including the speculation that the decay of DM particles results in a large velocity boost. We also find, in accord with previous works, that halos are triaxial and likely to be more prolate when unrelaxed, whereas relaxed halos are more likely to be oblate. Our analysis does not indicate that there is significant correlation (found in some previous studies) between the radial density slope, \gamma, and \beta\ at large radii, $0.3 r_{vir} < r < r_{vir}$.Comment: 12 pages, 17 figures, accepted to Ap

Determination of mercury in airborne particulate matter collected on glass fiber filters using high-resolution continuum source graphite furnace atomic absorption spectrometry and direct solid sampling

A study has been undertaken to assess the capability of high-resolution continuum source graphite furnace atomic absorption spectrometry for the determination of mercury in airborne particulate matter (APM) collected on glass fiber filters using direct solid sampling. The main Hg absorption line at 253.652 nm was used for all determinations. The certified reference material NIST SRM 1648 (Urban Particulate Matter) was used to check the accuracy of the method, and good agreement was obtained between published and determined values. The characteristic mass was 22 pg Hg. The limit of detection (3σ), based on ten atomizations of an unexposed filter, was 40 ng g- 1, corresponding to 0.12 ng m- 3 in the air for a typical air volume of 1440 m3 collected within 24 h. The limit of quantification was 150 ng g-1, equivalent to 0.41 ng m-3 in the air. The repeatability of measurements was better than 17% RSD (n = 5). Mercury concentrations found in filter samples loaded with APM collected in Buenos Aires, Argentina, were between < 40 ng g-1 and 381 ± 24 ng g-1. These values correspond to a mercury concentration in the air between < 0.12 ng m-3 and 1.47 ± 0.09 ng m-3. The proposed procedure was found to be simple, fast and reliable, and suitable as a screening procedure for the determination of mercury in APM samples.Fil: Araujo, Rennan G. O.. Universidade Federal de Santa Catarina; BrasilFil: Vignola, Fabíola. Universidade Federal de Santa Catarina; BrasilFil: Castilho, Ivan N. B.. Universidade Federal de Santa Catarina; BrasilFil: Borges, Daniel L. G.. Universidade Federal de Santa Catarina; Brasil. Universidade Federal da Bahia; BrasilFil: Welz, Bernhard. Universidade Federal de Santa Catarina; Brasil. Universidade Federal da Bahia; BrasilFil: Vale, Maria Goreti R.. Universidade Federal do Rio Grande do Sul; Brasil. Universidade Federal da Bahia; BrasilFil: Smichowski, Patricia Nora. Comisión Nacional de Energía Atómica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ferreira, Sérgio L. C.. Universidade Federal da Bahia; BrasilFil: Becker Ross, Helmut. Leibniz-Institut für Analytische Wissenschaften; Alemani

PERMEABILITY TO RESIDUAL WATER SATURATION IN OIL SATURATED PLUGS

ABSTRACT A series of laboratory experiments have been conducted to determine the permeability of brine close to irreducible water saturations with varying rock types, capillary pressures, saturations and permeabilities. X-ray tomography (CT) was used in one experiment as a quality assurance measure, visualizing the distribution of the flow of S wi phase in the sample. Water-saturated plugs attached to a water-wet ceramic membrane were drained by oil to S wi . Oil was then substituted by water at the inlet keeping both the water-and the oilsaturations in the plug constant. This was done in order to allow for water to flow through the plug and the membrane. A subsurface analogue to this laboratory experiment is a hydrocarbon-filled reservoir that is leaking water through a cap rock or a fault -keeping the hydrocarbons in place. The CT scan images showed that, although the overall flow rate was very low, the injected water moved quickly through the S wi -phase. Only a small fraction of the S wi volume contributed to this flow. The CT experiment also revealed some experimental artefacts such as spontaneous imbibition and gravity effects, which warrants further investigation. The result of the experiments verified that water could flow through different core plugs with varying S wi -phase permeability without forcing the oil through the membrane or changing the water saturation. The residual water permeability was dependent on the water saturation (S wi ) and the core plug permeability. Lowering the absolute permeability does not give a similar reduction in water permeability at S wi . The water permeability at S wi ranged from 0.02 µD to 1 µD. The absolute permeability for the different plugs ranged from approximately

Health- and oral health-related quality of life among preschool children with cerebral palsy

Objectives: To assess the health- and oral health-related quality of life of preschool children with cerebral palsy (CP) and to determine their inter-relationship between the two quality of life measures. Methods: A total of 144 preschool children with and without CP were invited to participate in the case-control study. Health-related quality of life was assessed by the Pediatric Quality of Life Inventory Version 4.0 (PedsQL™ 4.0) and oral health-related quality of life by the Early Childhood Oral Health Impact Scale (ECOHIS). Differences in PedsQL™ 4.0 and ECOHIS scores were determined between the groups, and correlation between PedsQL and ECOHIS were explored. Results: Significant differences in overall scores of PedsQL™ 4.0 (P < 0.001) and in overall scores of ECOHIS (P < 0.05) were apparent between the two groups. In terms of health- and oral health-related quality of life, preschool children with CP fared worse than the age-gender-matched control group. There was a positive albeit weak correlation (r = 0.203, P < 0.05) between PedsQL™ 4.0 and ECOHIS scores. Conclusions: Differences in health- and oral health-related quality of life exist among preschool children with CP. Correlation between health- and oral health-related quality of life could at best be described as weak. © 2010 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201

Limits on a Stochastic Background of Gravitational Waves from Gravitational Lensing

We compute the effects of a stochastic background of gravitational waves on multiply imaged systems or on weak lensing. There are two possible observable effects, a static relative deflection of images or shear, and an induced time dependent shift or proper motion. We evaluate the rms magnitude of these effects for a COBE normalized, scale-invariant spectrum, which is an upper limit on spectra produced by inflation. Previous work has shown that large-scale structure may cause a relative deflection large enough to affect observations, but we find that the corresponding effect of gravity waves is smaller by $\sim 10^4$ and so cannot be observed. This results from the oscillation in time as well as the redshifting of the amplitude of gravity waves. We estimate the magnitude of the proper motion induced by deflection of light due to large-scale structure, and find it to be $\sim 10^{-8}$ arcsec per year. This corresponds to $\sim 50$ km/s at cosmological distances, which is quite small compared to typical peculiar velocities. The COBE normalized gravity wave spectrum produces motions smaller still by $\sim 10^2$. We conclude that light deflection due to these cosmological perturbations cannot produce observable proper motions of lensed images. On the other hand, there are only a few known observational limits on a stochastic background of gravity waves at shorter, astrophysical wavelengths. We calculate the expected magnitudes of the effects of lensing by gravity waves of such wavelengths, and find that they are too small to yield interesting limits on the energy density of gravity waves.Comment: 14 pages, LaTex + 1 PS Figure, accepted version to be published in Phys. Rev. D15, Dec. 1996. An incorrect assumption was removed, also various other minor change

Mangiferin Decreases Plasma Free Fatty Acids through Promoting Its Catabolism in Liver by Activation of AMPK

Mangiferin has been shown to have the effect of improving dyslipidemia. Plasma free fatty acids (FFA) are closely associated with blood lipid metabolism as well as many diseases including metabolic syndrome. This study is to investigate whether mangiferin has effects on FFA metabolism in hyperlipidemic rats. Wistar rats were fed a high-fat diet and administered mangiferin simultaneously for 6 weeks. Mangiferin (50, 100, 150 mg/kg BW) decreased dose-dependently FFA and triglycerides (TG) levels in plasma, and their accumulations in liver, but increased the β-hydroxybutyrate levels in both plasma and liver of hyperlipidemic rats. HepG2 cells were treated with oleic acid (OA, 0.2 mmol/L) to simulate the condition of high level of plasma FFA in vitro, and were treated with different concentrations of mangiferin simultaneously for 24 h. We found that mangiferin significantly increased FFA uptake, significantly decreased intracellular FFA and TG accumulations in HepG2 cells. Mangiferin significantly increased AMP-activated protein kinase (AMPK) phosphorylation and its downstream proteins involved in fatty acid translocase (CD36) and carnitine palmitoyltransferase 1 (CPT1), but significantly decreased acyl-CoA: diacylgycerol acyltransferase 2 (DGAT2) expression and acetyl-CoA carboxylase (ACC) activity by increasing its phosphorylation level in both in vivo and in vitro studies. Furthermore, these effects were reversed by Compound C, an AMPK inhibitor in HepG2 cells. For upstream of AMPK, mangiferin increased AMP/ATP ratio, but had no effect on LKB1 phosphorylation. In conclusion, mangiferin decreased plasma FFA levels through promoting FFA uptake and oxidation, inhibiting FFA and TG accumulations by regulating the key enzymes expression in liver through AMPK pathway. Therefore, mangiferin is a possible beneficial natural compound for metabolic syndrome by improving FFA metabolism