244 research outputs found

    Chemical evolution using SPH cosmological simulations. I: implementation, tests and first results

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    We develop a model to implement metal enrichment in a cosmological context based on the hydrodynamical AP3MSPH code described by Tissera, Lambas and Abadi (1997).The star formation model is based on the Schmidt law and has been modified in order to describe the transformation of gas into stars in more detail. The enrichment of the interstellar medium due to supernovae I and II explosions is taken into account by assuming a Salpeter Initial Mass Function and different nucleosynthesis models.The different chemical elements are mixed within the gaseous medium according to the Smooth Particle Hydrodynamics technique. We present tests of the code that assess the effects of resolution and model parameters on the results. scenario and we present results of the analysis of the star formation and chemical properties of the interstellar medium and stellar population of the simulated galactic objects. We show that these systems reproduce abundance ratios for primary and secondary elements of the interstellar medium, and the correlation between the (O/H) abundance and the gas fraction of galaxies. The numerical simulations performed provide a detailed description of the chemical properties of galactic objects formed in hierarchical clustering scenarios and proved to be useful tools to deepen our understanding of galaxy formation and evolution.Comment: 36 pages, 9 Postscript figures. Final version (few changes),Acepted MNRA

    A systematic approach to the failed plastic surgical reconstruction of the diabetic foot

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    Plastic reconstruction for diabetic foot wounds must be approached carefully and follow sound micro-surgical principles as it relates to the anatomy of the designated flap chosen for coverage. First, the surgeon always needs to evaluate the local and general conditions of the presenting pathology and patient, respectively when considering a flap for reconstruction. The flap that is chosen is based on the vascularity, location, and size of the defect. Salvage of the failed flap and revisional reconstructive procedures are very challenging. Often, adjunctive therapies such as hyperbaric oxygen, negative pressure wound therapy, vasodilators, and/or vascular surgery is required. In certain case scenarios, such as patients with poor general health and compromised local vascularity in which revisional flap coverage cannot be performed, the above mentioned adjunctive therapies could be used as a primary treatment to potentially salvage a failing flap

    Mapping Cosmic Dawn and Reionization: Challenges and Synergies

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    Cosmic dawn and the Epoch of Reionization (EoR) are among the least explored observational eras in cosmology: a time at which the first galaxies and supermassive black holes formed and reionized the cold, neutral Universe of the post-recombination era. With current instruments, only a handful of the brightest galaxies and quasars from that time are detectable as individual objects, due to their extreme distances. Fortunately, a multitude of multi-wavelength intensity mapping measurements, ranging from the redshifted 21 cm background in the radio to the unresolved X-ray background, contain a plethora of synergistic information about this elusive era. The coming decade will likely see direct detections of inhomogenous reionization with CMB and 21 cm observations, and a slew of other probes covering overlapping areas and complementary physical processes will provide crucial additional information and cross-validation. To maximize scientific discovery and return on investment, coordinated survey planning and joint data analysis should be a high priority, closely coupled to computational models and theoretical predictions.Comment: 5 pages, 1 figure, submitted to the Astro2020 Decadal Survey Science White Paper cal

    Cosmology with the Highly Redshifted 21cm Line

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    In addition to being a probe of Cosmic Dawn and Epoch of Reionization astrophysics, the 21cm line at z>6z>6 is also a powerful way to constrain cosmology. Its power derives from several unique capabilities. First, the 21cm line is sensitive to energy injections into the intergalactic medium at high redshifts. It also increases the number of measurable modes compared to existing cosmological probes by orders of magnitude. Many of these modes are on smaller scales than are accessible via the CMB, and moreover have the advantage of being firmly in the linear regime (making them easy to model theoretically). Finally, the 21cm line provides access to redshifts prior to the formation of luminous objects. Together, these features of 21cm cosmology at z>6z>6 provide multiple pathways toward precise cosmological constraints. These include the "marginalizing out" of astrophysical effects, the utilization of redshift space distortions, the breaking of CMB degeneracies, the identification of signatures of relative velocities between baryons and dark matter, and the discovery of unexpected signs of physics beyond the Λ\LambdaCDM paradigm at high redshifts.Comment: Science white paper submitted to Decadal 2020 surve

    CONCERTO: Simulating the CO, [CII], and [CI] line emission of galaxies in a 117 deg2 field and the impact of field-to-field variance

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    In the submillimeter regime, spectral line scans and line intensity mapping (LIM) are new promising probes for the cold gas content and star formation rate of galaxies across cosmic time. However, both of these two measurements suffer from field-to-field variance. We study the effect of field-to-field variance on the predicted CO and [CII] power spectra from future LIM experiments such as CONCERTO, as well as on the line luminosity functions (LFs) and the cosmic molecular gas mass density that are currently derived from spectral line scans. We combined a 117 deg2 dark matter lightcone from the Uchuu cosmological simulation with the simulated infrared dusty extragalactic sky (SIDES) approach. The clustering of the dusty galaxies in the SIDES-Uchuu product is validated by reproducing the cosmic infrared background anisotropies measured by Herschel and Planck. We find that in order to constrain the CO LF with an uncertainty below 20%, we need survey sizes of at least 0.1 deg2. Furthermore, accounting for the field-to-field variance using only the Poisson variance can underestimate the total variance by up to 80%. The lower the luminosity is and the larger the survey size is, the higher the level of underestimate. At z < 3, the impact of field-to-field variance on the cosmic molecular gas density can be as high as 40% for the 4.6 arcmin2 field, but drops below 10% for areas larger than 0.2 deg2. However, at z > 3 the variance decreases more slowly with survey size and for example drops below 10% for 1 deg2 fields. Finally, we find that the CO and [CII] LIM power spectra can vary by up to 50% in 1 deg2 fields. This limits the accuracy of the constraints provided by the first 1 deg2 surveys. In addition the level of the shot noise power is always dominated by the sources that are just below the detection thresholds, which limits its potential for deriving number densities of faint [CII] emitters. We provide an analytical formula to estimate the field-to-field variance of current or future LIM experiments given their observed frequency and survey size. The underlying code to derive the field-to-field variance and the full SIDES-Uchuu products (catalogs, cubes, and maps) are publicly available

    QTLs of factors of the metabolic syndrome and echocardiographic phenotypes: the hypertension genetic epidemiology network study

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    <p>Abstract</p> <p>Background</p> <p>In a previous study of the Hypertension Genetic Epidemiology Network (HyperGEN) we have shown that metabolic syndrome (MetS) risk factors were moderately and significantly associated with echocardiographic (ECHO) left ventricular (LV) phenotypes.</p> <p>Methods</p> <p>The study included 1,393 African Americans and 1,133 whites, stratified by type 2 diabetes mellitus (DM) status. Heritabilities of seven factor scores based on the analysis of 15 traits were sufficiently high to pursue QTL discovery in this follow-up study.</p> <p>Results</p> <p>Three of the QTLs discovered relate to combined MetS-ECHO factors of "blood pressure (BP)-LV wall thickness" on chromosome 3 at 225 cM with a 2.8 LOD score, on chromosome 20 at 2.1 cM with a 2.6 LOD score; and for "LV wall thickness" factor on chromosome 16 at 113.5 with a 2.6 LOD score in whites. The remaining QTLs include one for a "body mass index-insulin (BMI-INS)" factor with a LOD score of 3.9 on chromosome 2 located at 64.8 cM; one for the same factor on chromosome 12 at 91.4 cM with a 3.3 LOD score; one for a "BP" factor on chromosome 19 located at 67.8 cM with a 3.0 LOD score. A suggestive linkage was also found for "Lipids-INS" with a 2.7 LOD score located on chromosome 11 at 113.1 cM in African Americans. Of the above QTLs, the one on chromosome 12 for "BMI-INS" is replicated in both ethnicities, (with highest LOD scores in African Americans). In addition, the QTL for "LV wall thickness" on chromosome 16q24.2-q24.3 reached its local maximum LOD score at marker D16S402, which is positioned within the 5th intron of the <it>cadherin 13 </it>gene, implicated in heart and vascular remodeling.</p> <p>Conclusion</p> <p>Our previous study and this follow-up suggest gene loci for some crucial MetS and cardiac geometry risk factors that contribute to the risk of developing heart disease.</p
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