1,860 research outputs found

    The effects of a sleep/recovery supplement: 'Night Time Recharge' on sleep parameters in young adults.

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    BACKGROUND: Concentrated cherry juice reportedly contains melatonin which, in turn, has been highlighted as an important regulator in initiating sleep. AIM: The present investigation aims to clarify whether Night Time Recharge (NTR), a marketed sleep aid containing cherry extract, improves key sleep parameters in young, active adults with mildly poor sleep. METHODS: A double-blind, randomized, placebo-controlled, cross-over study design was employed. Twenty participants (nine female) consumed either NTR or a placebo for seven days. Accelerometers were used to assess sleep quality and physical activity levels. Urinary levels of 6-sulphatoxymelatonin (6-SMT), a marker of melatonin synthesis, was assessed via enzyme-linked immunosorbent assay. RESULTS: 6-SMT levels increased following NTR treatment (28.95 ng/ml) compared with placebo (4.0 ng/ml) (p < 0.001). There was also a significant difference (p = 0.047) in dietary tryptophan consumption during the NTR treatment (1236 mg) versus placebo (1149 mg). No trace of melatonin was detected from our analysis of the supplement. NTR had no significant effect on any sleep parameters with the exception of sleep latency (p = 0.001). CONCLUSIONS: As chemical analysis of NTR by liquid-chromatography mass-spectrometry identified no detectable melatonin, the tryptophan content of the supplement is a likely reason for improvement in sleep latency. These results are in contrast to previous studies which have found a positive effect on sleep following cherry supplementation. Future work should focus on sleep latency and investigating whether cherry juice is effective in participants with problems in initiating sleep

    Mass-dependent evolution of the relation between supermassive black hole mass and host spheroid mass since z ~ 1

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    We investigate the evolution of supermassive black hole mass (M_BH) and the host spheroid mass (M_sph) in order to track the history of the M_BH-M_sph relationship. The typical mass increase of M_BH is calculated by a continuity equation and accretion history, which is estimated from the active galactic nucleus (AGN) luminosity function. The increase in M_sph is also calculated by using a continuity equation and a star formation model, which uses observational data for the formation rate and stellar mass function. We find that the black hole to spheroid mass ratio is expected to be substantially unchanged since z~1.2 for high mass objects (M_BH>10^8.5M_SUN and M_sph>10^11.3M_SUN). In the same redshift range, the spheroid mass is found to increase more rapidly than the black hole mass if M_sph>10^11M_SUN. The proposed mass-dependent model is consistent with the current available observational data in the M_BH-M_sph diagram.Comment: 15 pages, 8 figures, accepted to MNRA

    Evolution in the Disks and Bulges of Group Galaxies since z=0.4

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    We present quantitative morphology measurements of a sample of optically selected group galaxies at 0.3 < z < 0.55 using the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) and the GIM2D surface brightness--fitting software package. The group sample is derived from the Canadian Network for Observational Cosmology Field Redshift survey (CNOC2) and follow-up Magellan spectroscopy. We compare these measurements to a similarly selected group sample from the Millennium Galaxy Catalogue (MGC) at 0.05 < z < 0.12. We find that, at both epochs, the group and field fractional bulge luminosity (B/T) distributions differ significantly, with the dominant difference being a deficit of disk--dominated (B/T < 0.2) galaxies in the group samples. At fixed luminosity, z=0.4 groups have ~ 5.5 +/- 2 % fewer disk--dominated galaxies than the field, while by z=0.1 this difference has increased to ~ 19 +/- 6 %. Despite the morphological evolution we see no evidence that the group environment is actively perturbing or otherwise affecting the entire existing disk population. At both redshifts, the disks of group galaxies have similar scaling relations and show similar median asymmetries as the disks of field galaxies. We do find evidence that the fraction of highly asymmetric, bulge--dominated galaxies is 6 +/- 3 % higher in groups than in the field, suggesting there may be enhanced merging in group environments. We replicate our group samples at z=0.4 and z=0 using the semi-analytic galaxy catalogues of Bower et al (2006). This model accurately reproduces the B/T distributions of the group and field at z=0.1. However, the model does not reproduce our finding that the deficit of disks in groups has increased significantly since z=0.4.Comment: Accepted for publication in MNRAS. 20 pages, 17 figure

    E/S0 Galaxies on the Blue Color-Stellar Mass Sequence at z=0: Fading Mergers or Future Spirals?

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    We identify a population of morphologically defined E/S0 galaxies lying on the blue sequence at the present epoch. Using three samples, we analyze blue-sequence E/S0s with stellar masses >10^8 Msun, arguing that individual objects may be evolving either up toward the red sequence or down into the blue sequence. Blue-sequence E/S0 galaxies become more common with decreasing stellar mass, comprising <2% of E/S0s near the "shutdown mass" M_s ~ 1-2 x 10^11 Msun, increasing to >5% near the "bimodality mass" M_b ~ 3 x 10^10 Msun, and sharply rising to >20-30% below the "threshold mass" M_t ~ 4-6 x 10^9 Msun. The strong emergence of blue-sequence E/S0s below M_t coincides with a previously reported global increase in mean atomic gas fractions below M_t for galaxies of all types on both sequences, suggesting that the availability of cold gas may be basic to blue-sequence E/S0s' existence. Environmental analysis reveals that many sub-M_b blue-sequence E/S0s reside in low to intermediate density environments. In mass-radius and mass-sigma scaling relations, blue-sequence E/S0s are more similar to red-sequence E/S0s than to late-type galaxies, but they represent a transitional class. While some of them, especially in the high-mass range from M_b to M_s, resemble major-merger remnants that will likely fade onto the red sequence, most blue-sequence E/S0s below M_b show signs of disk and/or pseudobulge building, which may be enhanced by companion interactions. We argue that sub-M_b blue-sequence E/S0s occupy a "sweet spot" in stellar mass and concentration, with both abundant gas and optimally efficient star formation, which may enable the formation of large spiral disks. [abridged]Comment: AJ, submitted, revised, 21 pages with 15 figures (one in two parts, one color); full resolution version available at http://www.physics.unc.edu/~sheila/kgb.pd

    The Rise of Massive Red Galaxies: the color-magnitude and color-stellar mass diagrams for z < ~2 from the MUltiwavelength Survey by Yale-Chile (MUSYC)

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    We present the color-magnitude and color-stellar mass diagrams for galaxies with z_phot < ~2, based on a K < 22 (AB) catalog of the Extended Chandra Deep Field South (ECDFS) from the MUltiwavelength Survey by Yale-Chile (MUSYC). Our main sample of 7840 galaxies contains 1297 M_* > 10^11 M_Sol galaxies in the range 0.2 < z_phot < 1.8. We show empirically that this catalog is approximately complete for M_* > 10^11 M_Sol galaxies for z_phot < 1.8. For this mass-limited sample, we show that the locus of the red sequence color-stellar mass relation evolves as Del(u-r) ~ (-0.44+/-0.02) z_phot for z_phot ~1.3, however, we are no longer able to reliably distinguish red and blue subpopulations from the observed color distribution; we show that this would require much deeper near infrared data. At 1.5 < z_phot 10^11 M_Sol galaxies is ~50% of the local value, with a red fraction of ~33%. Making a parametric fit to the observed evolution, we find n_tot(z) ~ (1+z_phot)^(-0.52+/-0.12(+/-0.20)). We find stronger evolution in the red fraction: f_red(z) ~ (1+z_phot)^(-1.17+/-0.18(+/-0.21)). Through a series of sensitivity analyses, we show that the most important sources of systematic error are: 1. systematic differences in the analysis of the z~0 and z>>0 samples; 2. systematic effects associated with details of the photometric redshift calculation; and 3. uncertainties in the photometric calibration. With this in mind, we show that our results based on photometric redshifts are consistent with a completely independent analysis which does not require redshift information for individual galaxies. Our results suggest that, at most, 1/5 of local red sequence galaxies with M_* >10^11 M_Sol were already in place at z ~ 2.Comment: Accepted for publication in ApJ. 31 pages in emulateapj format; 18 figues (14 in main text). Additional online data available through http://www.strw.leidenuniv.nl/~ent

    f(R)f(R) gravity theories in the Palatini Formalism constrained from strong lensing

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    f(R)f(R) gravity, capable of driving the late-time acceleration of the universe, is emerging as a promising alternative to dark energy. Various f(R)f(R) gravity models have been intensively tested against probes of the expansion history, including type Ia supernovae (SNIa), the cosmic microwave background (CMB) and baryon acoustic oscillations (BAO). In this paper we propose to use the statistical lens sample from Sloan Digital Sky Survey Quasar Lens Search Data Release 3 (SQLS DR3) to constrain f(R)f(R) gravity models. This sample can probe the expansion history up to z2.2z\sim2.2, higher than what probed by current SNIa and BAO data. We adopt a typical parameterization of the form f(R)=RαH02(RH02)βf(R)=R-\alpha H^2_0(-\frac{R}{H^2_0})^\beta with α\alpha and β\beta constants. For β=0\beta=0 (Λ\LambdaCDM), we obtain the best-fit value of the parameter α=4.193\alpha=-4.193, for which the 95% confidence interval that is [-4.633, -3.754]. This best-fit value of α\alpha corresponds to the matter density parameter Ωm0=0.301\Omega_{m0}=0.301, consistent with constraints from other probes. Allowing β\beta to be free, the best-fit parameters are (α,β)=(3.777,0.06195)(\alpha, \beta)=(-3.777, 0.06195). Consequently, we give Ωm0=0.285\Omega_{m0}=0.285 and the deceleration parameter q0=0.544q_0=-0.544. At the 95% confidence level, α\alpha and β\beta are constrained to [-4.67, -2.89] and [-0.078, 0.202] respectively. Clearly, given the currently limited sample size, we can only constrain β\beta within the accuracy of Δβ0.1\Delta\beta\sim 0.1 and thus can not distinguish between Λ\LambdaCDM and f(R)f(R) gravity with high significance, and actually, the former lies in the 68% confidence contour. We expect that the extension of the SQLS DR3 lens sample to the SDSS DR5 and SDSS-II will make constraints on the model more stringent.Comment: 10 pages, 7 figures. Accepted for publication in MNRA

    The morphologies and masses of extremely red galaxies in the Groth Strip survey

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    We present a new cataloge of EROs from the Groth strip and study the relation between their morphology and mass. We find 102 EROs (F814W-K=>4, K<=21.0), over a survey area of 155 arcmin^2. The photometric data include U,B,F606W,F814W,J,K bands. Morphologies are based on a by eye classification and we distinguish between 3 basic classes: compact objects, targets with a disc and/or a bulge component and irregular or merger candidates. The majority of our targets has either a very compact morphology (33+-6%), or show more or less distinct disc components (41+-6%). 14+-4% are merger or irregulars and 7 objects could not be classified. We also study the dependence of structural parameters on morphological appearance. EROs that are either compact or show a distinct bulge component have smaller median effective radii (1.22+-0.14 kpc and 3.31+-0.53 kpc) than disc dominated (5.50+-0.51 kpc) or possible irregular galaxies or merger candidates (4.92+-0.14 kpc). The Sersic index changes from 2.30+-0.34 and 3.24+-0.55, to 1.03+-0.24 and 1.54+-0.40 respectively. Most the EROs in our sample have redshifts between z=1 and z=2; however, compact EROs in our sample are found at redshifts as low as z=0.4 and as high as z=2.8; the latter qualify as well as DRGs. Disc-like EROs are also found up to z=2.8; however those with a bulge-disc structure are only seen at z<1.5. For each of these EROs we determined the stellar mass and mean population age by fitting synthetic Bruzual (2007) spectra to the SED. Mass estimates were obtained by assuming an exponentially declining star formation rate. Total stellar masses are in the range 9.1<log(M/M_sun)<11.6. We cannot detect significant differences between the stellar mass distribution of the morphological classes. EROs with masses of log(M/M_sun)>11.0 dominantly show compact morphologies, but also include a significant number of sources with a disc morphology.Comment: 21 pages, 17 figures, accepted for publication in MNRA

    Automated Morphological Classification of SDSS Red Sequence Galaxies

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    (abridged) In the last decade, the advent of enormous galaxy surveys has motivated the development of automated morphological classification schemes to deal with large data volumes. Existing automated schemes can successfully distinguish between early and late type galaxies and identify merger candidates, but are inadequate for studying detailed morphologies of red sequence galaxies. To fill this need, we present a new automated classification scheme that focuses on making finer distinctions between early types roughly corresponding to Hubble types E, S0, and Sa. We visually classify a sample of 984 non-starforming SDSS galaxies with apparent sizes >14". We then develop an automated method to closely reproduce the visual classifications, which both provides a check on the visual results and makes it possible to extend morphological analysis to much larger samples. We visually classify the galaxies into three bulge classes (BC) by the shape of the light profile in the outer regions: discs have sharp edges and bulges do not, while some galaxies are intermediate. We separately identify galaxies with features: spiral arms, bars, clumps, rings, and dust. We find general agreement between BC and the bulge fraction B/T measured by the galaxy modeling package GIM2D, but many visual discs have B/T>0.5. Three additional automated parameters -- smoothness, axis ratio, and concentration -- can identify many of these high-B/T discs to yield automated classifications that agree ~70% with the visual classifications (>90% within one BC). Both methods are used to study the bulge vs. disc frequency as a function of four measures of galaxy 'size': luminosity, stellar mass, velocity dispersion, and radius. All size indicators show a fall in disc fraction and a rise in bulge fraction among larger galaxies.Comment: 24 pages, 20 figures, MNRAS accepte

    Mapping dusty star formation in and around a cluster at z=0.81 by wide-field imaging with AKARI

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    We present environmental dependence of dusty star forming activity in and around the cluster RXJ1716.4+6708 at z=0.81 based on wide-field and multi-wavelength observations with Suprime-Cam on the Subaru telescope and IRC onboard the AKARI satellite. Our optical data shows that the optical colour distribution of galaxies starts to dramatically change from blue to red at the medium-density environment such as cluster outskirts, groups and filaments. By combining with infrared data, we find that 15 micron galaxies tend to have optical colours between the red sequence and the blue cloud with a tail into the red sequence. The spatial distribution of the 15 micron galaxies over ~200 arcmin^2 around the cluster reveals that few 15 micron galaxies are detected in the cluster central region. This is probably due to the low star forming activity in the cluster core. However, interestingly, the fraction of 15 micron galaxies in the medium-density environments is as high as in the low-density field, despite the fact that the optical colours start to change in the medium-density environments. Furthermore, we find that 15 micron galaxies which have optically red colours (candidates for dusty red galaxies) and galaxies with high specific star formation rates are also concentrated in the medium-density environment. These results imply that the star forming activity in galaxies in groups and filaments is enhanced due to some environmental effects specific to the medium-density environment, and such a phenomenon is probably directly connected to the truncation of star forming activity in galaxies seen as the dramatic change in optical colours in such environments.Comment: 15 pages, 14 figures, accepted for publication in MNRA

    Molecular characterisation of protist parasites in human-habituated mountain gorillas (Gorilla beringei beringei), humans and livestock, from Bwindi impenetrable National Park, Uganda

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    Over 60 % of human emerging infectious diseases are zoonotic, and there is growing evidence of the zooanthroponotic transmission of diseases from humans to livestock and wildlife species, with major implications for public health, economics, and conservation. Zooanthroponoses are of relevance to critically endangered species; amongst these is the mountain gorilla (Gorilla beringei beringei) of Uganda. Here, we assess the occurrence of Cryptosporidium, Cyclospora, Giardia, and Entamoeba infecting mountain gorillas in the Bwindi Impenetrable National Park (BINP), Uganda, using molecular methods. We also assess the occurrence of these parasites in humans and livestock species living in overlapping/adjacent geographical regions
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