337 research outputs found

    Coral Gardens Reef, Belize: A Refugium in the Face of Caribbean-Wide \u3ci\u3eAcropora\u3c/i\u3e Spp. Coral Decline

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    Caribbean Acropora spp. corals have undergone a decline in cover since the second half of the twentieth century. Loss of these architecturally complex and fast-growing corals has resulted in significant, cascading changes to the character, diversity, and available eco spaces of Caribbean reefs. Few thriving Acropora spp. populations exist today in the Caribbean and western North Atlantic seas, and our limited ability to access data from reefs assessed via long-term monitoring efforts means that reef scientists are challenged to determine resilience and longevity of existing Acropora spp. reefs. Here we used multiple dating methods to measure reef longevity and determine whether Coral Gardens Reef, Belize, is a refuge for Acropora cervicornis against the backdrop of wider Caribbean decline. We used a new genetic-aging technique to identify sample sites, and radiocarbon and high-precision uranium-thorium (U-Th) dating techniques to test whether one of the largest populations of extant A. cervicornis in the western Caribbean is newly established after the 1980s, or represents a longer-lived, stable population. We did so with respect for ethical sampling of a threatened species. Our data show corals ranging in age from 1910 (14C) or 1915 (230Th) to at least November 2019. While we cannot exclude the possibility of short gaps in the residence of A. cervicornis earlier in the record, the data show consistent and sustained living coral throughout the 1980s and up to at least 2019. We suggest that Coral Gardens has served as a refuge for A. cervicornis and that identifying other, similar sites may be critical to efforts to grow, preserve, conserve, and seed besieged Caribbean reefs

    Improved Photometric Redshifts with Surface Luminosity Priors

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    We apply Bayesian statistics with prior probabilities of galaxy surface luminosity (SL) to improve photometric redshifts. We apply the method to a sample of 1266 galaxies with spectroscopic redshifts in the GOODS North and South fields at 0.1 < z < 2.0. We start with spectrophotometric redshifts (SPZs) based on Probing Evolution and Reionization Spectroscopically grism spectra, which cover a wavelength range of 6000-9000A, combined with (U)BViz(JHK) broadband photometry in the GOODS fields. The accuracy of SPZ redshifts is estimated to be \sigma (\Delta(z))=0.035 with an systematic offset of -0.026, where \Delta(z)=\Delta z / (1+z), for galaxies in redshift range of 0.5 < z < 1.25. The addition of the SL prior probability helps break the degeneracy of SPZ redshifts between low redshift 4000 A break galaxies and high-redshift Lyman break galaxies which are mostly catastrophic outliers. For the 1138 galaxies at z < 1.6, the fraction of galaxies with redshift deviation \Delta (z) > 0.2 is reduced from 15.0% to 10.4%, while the rms scatter of the fractional redshift error does not change much.Comment: 7 pages, 7 figures, published in A

    The potential of food fortification to add micronutrients in young children and women of reproductive age - findings from a cross-sectional survey in Abidjan, Côte d'Ivoire

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    Poor micronutrient intakes are a major contributing factor to the high burden of micronutrient deficiencies in Côte d'Ivoire. Large-scale food fortification is considered a cost-effective approach to deliver micronutrients, and fortification of salt (iodine), wheat flour (iron and folic acid), and vegetable oil (vitamin A) is mandatory in Côte d'Ivoire. A cross-sectional survey on households with at least one child 6-23 months was conducted to update coverage figures with adequately fortified food vehicles in Abidjan, the capital of and largest urban community in Côte d'Ivoire, and to evaluate whether additional iron and vitamin A intake is sufficient to bear the potential to reduce micronutrient malnutrition. Information on demographics and food consumption was collected, along with samples of salt and oil. Wheat flour was sampled from bakeries and retailers residing in the selected clusters. In Abidjan, 86% and 97% of salt and vegetable oil samples, respectively, were adequately fortified, while only 32% of wheat flour samples were adequately fortified, but all samples contained some added iron. There were no major differences in additional vitamin A and iron intake between poor and non-poor households. For vitamin A in oil, the additional percentage of the recommended nutrient intake was 27% and 40% for children 6-23 months and women of reproductive age, respectively, while for iron from wheat flour, only 13% and 19% could be covered. Compared to previous estimates, coverage has remained stable for salt and wheat flour, but improved for vegetable oil. Fortification of vegetable oil clearly provides a meaningful additional amount of vitamin A. This is not currently the case for iron, due to the low fortification levels. Iron levels in wheat flour should be increased and monitored, and additional vehicles should be explored to add iron to the Ivorian diet

    National Prevalence of Micronutrient Deficiencies, Anaemia, Genetic Blood Disorders and Over- and Undernutrition in Omani Women of Reproductive Age and Preschool Children

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    A national cross-sectional survey was conducted to estimate the prevalence of anaemia, micronutrient deficiencies, haemoglobin disorders and over- and undernutrition in children and women of reproductive age in Oman. Wasting and stunting were found in 9.3% and 11.4% of children aged 0–59 months, respectively, while 4.2% were overweight or obese. In addition, 23.8% were anaemic and 10.2%, 9.5% and 10.6% had iron, vitamin A and vitamin D deficiencies, respectively. Sickle cell and β-thalassaemia genetic traits were present in 5.3% and 4.2% of children and 4.7% and 2.8% of women, respectively. Overall, 9.1% of Omani women were underweight and 59.2% were overweight or obese. The prevalence of anaemia was 27.8%, while iron, folate, vitamin B12 and vitamin D deficiencies affected 24.8%, 11.6%, 8.9% and 16.2%, respectively. Anaemia among both children and women and the prevalence of overweight and obesity in women are the most concerning nutritional problems in Oman.Keywords: Nutrition Disorders; Malnutrition; Micronutrients; Iron-Deficiency Anemia; Avitaminosis; Vitamin D Deficiency; Vitamin B 12 Deficiency; Oman

    On the unification of dwarf and giant elliptical galaxies

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    The near orthogonal distributions of dwarf elliptical (dE) and giant elliptical (E) galaxies in the mu_e-Mag and mu_e-log(R_e) diagrams have been interpreted as evidence for two distinct galaxy formation processes. However, continuous, linear relationships across the alleged dE/E boundary at M_B = -18 mag - such as those between central surface brightness (mu_0) and (i) galaxy magnitude and (ii) light-profile shape (n) - suggest a similar, governing formation mechanism. Here we explain how these latter two linear trends necessitate a different behavior for dE and E galaxies, exactly as observed, in diagrams involving mu_e (and also _e). A natural consequence is that the distribution of dEs and Es in Fundamental Plane type analyses that use the associated intensity I_e, or _e, are expected to appear different. Together with other linear trends across the alleged dE/E boundary, such as those between luminosity and color, metallicity, and velocity dispersion, it appears that the dEs form a continuous extension to the E galaxies. The presence of partially depleted cores in luminous (M_B < -20.5 mag) Es does however signify the action of a different physical process at the centers (< ~300 pc) of these galaxies.Comment: 5 pages from the proceedings of the 2004 conference "Penetrating bars through masks of cosmic dust: the Hubble tuning fork strikes a new note". Edited by D. L. Block, I. Puerari, K. C. Freeman, R. Groess, and E. K. Bloc

    Molecular Gas in the z=1.2 Ultraluminous Merger GOODS J123634.53+621241.3

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    We report the detection of CO(2-1) emission from the z=1.2 ultraluminous infrared galaxy (ULIRG) GOODS J123634.53+621241.3 (also known as the sub-millimeter galaxy GN26). These observations represent the first discovery of high-redshift CO emission using the new Combined Array for Research in Millimeter-Wave Astronomy (CARMA). Of all high-redshift (z>1) galaxies within the GOODS-North field, this source has the largest far-infrared (FIR) flux observed in the Spitzer 70um and 160um bands. The CO redshift confirms the optical identification of the source, and the bright CO(2-1) line suggests the presence of a large molecular gas reservoir of about 7x10^10 M(sun). The infrared-to-CO luminosity ratio of L(IR)/L'(CO) = 80+/-30 L(sun) (K Km/s pc^2)^-1 is slightly smaller than the average ratio found in local ULIRGs and high-redshift sub-millimeter galaxies. The short star-formation time scale of about 70 Myr is consistent with a starburst associated with the merger event and is much shorter than the time scales for spiral galaxies and estimates made for high-redshift galaxies selected on the basis of their B-z and z-K colors.Comment: Accepted for publication in ApJ Letter

    Early-type galaxies in the PEARS survey: Probing the stellar populations at moderate redshift

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    Using HST/ACS slitless grism spectra from the PEARS program, we study the stellar populations of morphologically selected early-type galaxies in the GOODS North and South fields. The sample - extracted from a visual classification of the (v2.0) HST/ACS images and restricted to redshifts z>0.4 - comprises 228 galaxies (F775W<24 ABmag) out to z~1.3 over 320 arcmin2, with a median redshift zM=0.75. This work significantly increases our previous sample from the GRAPES survey in the HUDF (18 galaxies over ~11 arcmin2; Pasquali et al. 2006b). The grism data allow us to separate the sample into `red' and `blue' spectra, with the latter comprising 15% of the total. Three different grids of models parameterising the star formation history are used to fit the low-resolution spectra. Over the redshift range of the sample - corresponding to a cosmic age between 5 and 10 Gyr - we find a strong correlation between stellar mass and average age, whereas the **spread** of ages (defined by the RMS of the distribution) is roughly ~1 Gyr and independent of stellar mass. The best-fit parameters suggest it is formation epoch and not formation timescale, that best correlates with mass in early-type galaxies. This result - along with the recently observed lack of evolution of the number density of massive galaxies - motivates the need for a channel of (massive) galaxy formation bypassing any phase in the blue cloud, as suggested by the simulations of Dekel et al. (2009).Comment: 12 pages, 12 figures, 3 tables. Submitted for publication in Ap

    The host metabolite D-serine contributes to bacterial niche specificity through gene selection

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    Escherichia coli comprise a diverse array of both commensals and niche-specific pathotypes. The ability to cause disease results from both carriage of specific virulence factors and regulatory control of these via environmental stimuli. Moreover, host metabolites further refine the response of bacteria to their environment and can dramatically affect the outcome of the host–pathogen interaction. Here, we demonstrate that the host metabolite, D-serine, selectively affects gene expression in E. coli O157:H7. Transcriptomic profiling showed exposure to D-serine results in activation of the SOS response and suppresses expression of the Type 3 Secretion System (T3SS) used to attach to host cells. We also show that concurrent carriage of both the D-serine tolerance locus (dsdCXA) and the locus of enterocyte effacement pathogenicity island encoding a T3SS is extremely rare, a genotype that we attribute to an ‘evolutionary incompatibility’ between the two loci. This study demonstrates the importance of co-operation between both core and pathogenic genetic elements in defining niche specificity
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