2,083 research outputs found

    The Origin of the [C II] Deficit in a Simulated Dwarf Galaxy Merger-driven Starburst

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    We present [C II] synthetic observations of smoothed particle hydrodynamics (SPH) simulations of a dwarf galaxy merger. The merging process varies the star formation rate (SFR) by more than three orders of magnitude. Several star clusters are formed, the feedback of which disperses and unbinds the dense gas through expanding H II regions and supernova (SN) explosions. For galaxies with properties similar to the modeled ones, we find that the [C II] emission remains optically thin throughout the merging process. We identify the warm neutral medium (3 2 chi(H2)) to be the primary source of [C II] emission (similar to 58% contribution), although at stages when the H II regions are young and dense (during star cluster formation or SNe in the form of ionized bubbles), they can contribute greater than or similar to 50% to the total [C II] emission. We find that the [C II]/far-IR (FIR) ratio decreases owing to thermal saturation of the [C II] emission caused by strong far-UV radiation fields emitted by the massive star clusters, leading to a [C II] deficit medium. We investigate the [C II]-SFR relation and find an approximately linear correlation that agrees well with observations, particularly those from the Dwarf Galaxy Survey. Our simulation reproduces the observed trends of [C II]/FIR versus Sigma(S)(FR) and Sigma(FIR), and it agrees well with the Kennicutt relation of SFR-FIR luminosity. We propose that local peaks of [C II] resolved observations may provide evidence for ongoing massive cluster formation.Peer reviewe

    Heredabilidades para características de crecimiento a través de los años en la raza Blanco Orejinegro

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    The aim of this study was to estimate the values of direct and maternal heritability and the variances due to the permanent environment from 1990 to 2012 in the Colombian Creole Blanco Orejinegro breed. In total, 10 698 data on growth variables were analyzed for birth weight (BW), adjusted weight at 240 days (PAJ240) and adjusted weight at 480 days (PAJ480). The derivative-free restricted maximum likelihood methodology (DFREML) was used, adjusting an animal model that included direct genetic effects, maternal and variations due to the permanent environment, assuming as fixed effects the year, time of birth, the sex of the calf and as covariate the mother's age at delivery. The heritability for BW were h²d = 0.31, h²m = 0.03 and σ²c = 0.07. the heritability values for PAJ240 were moderate and low (h²d = 0.18, h²m = 0.05, σ²c = 0.04) while for PAJ480 they were h²d = 0.17, h²m = 0.04, σ²c = 0.06, without presenting significant values and the proportion of the variances presented negative and decreasing values on the line. The genetic trends were increasing and decreasing, indicating that the environmental variance negatively affects the maternal component and the permanent environment for the weight at 240 and 480 days, respectively.El objetivo del estudio fue estimar los valores de heredabilidad directa, materna y las varianzas debidas al ambiente permanente desde año 1990 hasta 2012 en la raza criolla colombiana Blanco Orejinegro. Se analizaron 10 698 datos sobre las variables de crecimiento para peso al nacimiento (PN), peso ajustado a los 240 días (PAJ240) y peso ajustado a los 480 días (PAJ480). Se utilizó la metodología de máxima verosimilitud restringida libre de derivadas (DFREML), ajustando un modelo animal que incluyó efectos genéticos directos, maternos y variaciones debidas al ambiente permanente, asumiendo como efectos fijos el año, época de nacimiento, el sexo del ternero y como covariable la edad de la madre al parto. Las heredabilidades para PN fueron de h²d = 0.31, h²m = 0.03 y σ²c = 0.07. los valores de heredabilidad para PAJ240 fueron moderados y bajos (h²d = 0.18, h²m = 0.05, σ²c = 0.04) en tanto que para PAJ480 fueron de h²d = 0.17, h²m = 0.04, σ²c = 0.06, sin presentar valores significativos, y la proporción de las varianzas presentaron valores negativos y decreciente en la recta. Las tendencias genéticas fueron creciente y decreciente, indicando que la varianza ambiental afecta negativamente el componente materno y del ambiente permanente para el peso a los 240 y 480 días respectivamente

    Measurements in two bases are sufficient for certifying high-dimensional entanglement

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    High-dimensional encoding of quantum information provides a promising method of transcending current limitations in quantum communication. One of the central challenges in the pursuit of such an approach is the certification of high-dimensional entanglement. In particular, it is desirable to do so without resorting to inefficient full state tomography. Here, we show how carefully constructed measurements in two bases (one of which is not orthonormal) can be used to faithfully and efficiently certify bipartite high-dimensional states and their entanglement for any physical platform. To showcase the practicality of this approach under realistic conditions, we put it to the test for photons entangled in their orbital angular momentum. In our experimental setup, we are able to verify 9-dimensional entanglement for a pair of photons on a 11-dimensional subspace each, at present the highest amount certified without any assumptions on the state.Comment: 11+14 pages, 2+7 figure

    Geobiology of Andean Microbial Ecosystems Discovered in Salar de Atacama, Chile

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    The Salar de Atacama in the Chilean Central Andes harbors unique microbial ecosystems due to extreme environmental conditions, such as high altitude, low oxygen pressure, high solar radiation, and high salinity. Combining X-ray diffraction analyses, scanning electron microscopy and molecular diversity studies, we have characterized twenty previously unexplored Andean microbial ecosystems in eight different lakes and wetlands from the middle-east and south-east regions of this salt flat. The mats and microbialites studied are mainly formed by calcium carbonate (aragonite and calcite) and halite, whereas the endoevaporites are composed predominantly of gypsum and halite. The carbonate-rich mats and microbialites are dominated by Bacteroidetes and Proteobacteria phyla. Within the phylum Proteobacteria, the most abundant classes are Alphaproteobacteria, Gammaproteobacteria and Deltaproteobacteria. While in the phylum Bacteroidetes, the most abundant classes are Bacteroidia and Rhodothermia. Cyanobacteria, Chloroflexi, Planctomycetes, and Verrucomicrobia phyla are also wellrepresented in the majority of these systems. Gypsum endoevaporites, on the contrary, are dominated by Proteobacteria, Bacteroidetes, and Euryarchaeota phyla. The Cyanobacteria phylum is also abundant in these systems, but it is less represented in comparison to mats and microbialites. Regarding the eukaryotic taxa, diatoms are key structural components in most of the microbial ecosystems studied. The genera of diatoms identified were Achnanthes, Fallacia, Halamphora, Mastogloia, Navicula, Nitzschia, and Surirella. Normally, in the mats and microbialites, diatoms form nano-globular carbonate aggregates with filamentous cyanobacteria and other prokaryotic cells, suggesting their participation in the mineral precipitation process. This work expands our knowledge of the microbial ecosystems inhabiting the extreme environments from the Central Andes region, which is important to ensure their protection and conservation.Centro de Investigaciones Geológica

    Melancholic versus non-melancholic depression: differences on cognitive function. A longitudinal study protocol

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    <p>Abstract</p> <p>Background</p> <p>Cognitive dysfunction is common among depressed patients. However, the pattern and magnitude of impairment during episodes of major depressive disorder (MDD) through to clinical remission remains unclear. Heterogeneity of depressive patients and the lack of longitudinal studies may account for contradictory results in previous research.</p> <p>Methods/Design</p> <p>This longitudinal study will analyze cognitive differences between CORE-defined melancholic depressed patients (n = 60) and non-melancholic depressed patients (n = 60). A comprehensive clinical and cognitive assessment will be performed at admission and after 6 months. Cognitive dysfunction in both groups will be longitudinally compared, and the persistence of cognitive impairment after clinical remission will be determined.</p> <p>Discussion</p> <p>The study of neuropsychological dysfunction and the cognitive changes through the different phases of depression arise a wide variety of difficulties. Several confounding variables must be controlled to determine if the presence of depression could be considered the only factor accounting for group differences.</p

    17q21 variant increases the risk of exacerbations in asthmatic children despite inhaled corticosteroids use

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    _To the Editor,_ Approximately 25% of the asthmatic children suffer from uncontrolled asthma despite regular use of inhaled corticosteroids (ICS). Variation within the 17q21 locus is the strongest genetic determinant for childhood‐onset asthma. Recently, the influence of this locus on treatment outcomes has been shown in several studies. The Pharmacogenomics in Childhood Asthma (PiCA) consortium is a multiethnic consortium that brings together data from ≥14 000 asthmatic children/young adults from 12 different countries to study the pharmacogenomics of uncontrolled asthma despite treatment. In 14 PiCA populations (with over 4000 asthmatic patients), we studied the association between variation in the 17q21 locus, and asthma exacerbations despite ICS use. We specifically focused on rs7216389, a single nucleotide polymorphism (SNP) in the 17q21 locus strongly associated with childhood asthma and initially identified by Moffatt et al. [...

    Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

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    BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London

    LTA4H rs2660845 association with montelukast response in early and late-onset asthma

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    Leukotrienes play a central pathophysiological role in both paediatric and adult asthma. However, 35% to 78% of asthmatics do not respond to leukotriene inhibitors. In this study we tested the role of the LTA4H regulatory variant rs2660845 and age of asthma onset in response to montelukast in ethnically diverse populations. We identified and genotyped 3,594 asthma patients treated with montelukast (2,514 late-onset and 1,080 early-onset) from seven cohorts (UKBiobank, GoSHARE, BREATHE, Tayside RCT, PAGES, GALA II and SAGE). Individuals under montelukast treatment experiencing at least one exacerbation in a 12-month period were compared against individuals with no exacerbation, using logistic regression for each cohort and meta-analysis. While no significant association was found with European late-onset subjects, a meta-analysis of 523 early-onset individuals from European ancestry demonstrated the odds of experiencing asthma exacerbations by carriers of at least one G allele, despite montelukast treatment, were increased (odds-ratio = 2.92, 95%confidence interval (CI): 1.04–8.18, I2 = 62%, p = 0.0412) compared to those in the AA group. When meta-analysing with other ethnic groups, no significant increased risk of asthma exacerbations was found (OR = 1.60, 95% CI: 0.61–4.19, I2 = 85%, p = 0.342). Our study demonstrates that genetic variation in LTA4H, together with timing of asthma onset, may contribute to variability in montelukast response. European individuals with early-onset (≤18y) carrying at least one copy of rs2660845 have increased odd of exacerbation under montelukast treatment, presumably due to the up-regulation of LTA4H activity. These findings support a precision medicine approach for the treatment of asthma with montelukast

    Identification of a novel locus on chromosome 2q13, which predisposes to clinical vertebral fractures independently of bone density.

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    OBJECTIVES: To identify genetic determinants of susceptibility to clinical vertebral fractures, which is an important complication of osteoporosis. METHODS: Here we conduct a genome-wide association study in 1553 postmenopausal women with clinical vertebral fractures and 4340 controls, with a two-stage replication involving 1028 cases and 3762 controls. Potentially causal variants were identified using expression quantitative trait loci (eQTL) data from transiliac bone biopsies and bioinformatic studies. RESULTS: A locus tagged by rs10190845 was identified on chromosome 2q13, which was significantly associated with clinical vertebral fracture (P=1.04×10-9) with a large effect size (OR 1.74, 95% CI 1.06 to 2.6). Bioinformatic analysis of this locus identified several potentially functional SNPs that are associated with expression of the positional candidate genes TTL (tubulin tyrosine ligase) and SLC20A1 (solute carrier family 20 member 1). Three other suggestive loci were identified on chromosomes 1p31, 11q12 and 15q11. All these loci were novel and had not previously been associated with bone mineral density or clinical fractures. CONCLUSION: We have identified a novel genetic variant that is associated with clinical vertebral fractures by mechanisms that are independent of BMD. Further studies are now in progress to validate this association and evaluate the underlying mechanism
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