204 research outputs found

    Apples to apples A^2 – II. Cluster selection functions for next-generation surveys

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    We present the cluster selection function for three of the largest next-generation stage-IV surveys in the optical and infrared: Euclid-Optimistic, Euclid-Pessimistic and the Large Synoptic Survey Telescope (LSST). To simulate these surveys, we use the realistic mock catalogues introduced in the first paper of this series. We detected galaxy clusters using the Bayesian Cluster Finder in the mock catalogues. We then modelled and calibrated the total cluster stellar mass observable–theoretical mass (M^∗_(CL)—M_h) relation using a power-law model, including a possible redshift evolution term. We find a moderate scatter of σM^∗_(CL)|M_h) of 0.124, 0.135 and 0.136 dex for Euclid-Optimistic, Euclid-Pessimistic and LSST, respectively, comparable to other work over more limited ranges of redshift. Moreover, the three data sets are consistent with negligible evolution with redshift, in agreement with observational and simulation results in the literature. We find that Euclid-Optimistic will be able to detect clusters with >80 per cent completeness and purity down to 8 × 10^(13) h^(−1) M_⊙ up to z < 1. At higher redshifts, the same completeness and purity are obtained with the larger mass threshold of 2 × 10^(14) h^(−1) M_⊙ up to z = 2. The Euclid-Pessimistic selection function has a similar shape with ∼10 per cent higher mass limit. LSST shows ∼5 per cent higher mass limit than Euclid-Optimistic up to z < 0.7 and increases afterwards, reaching a value of 2 × 10^(14) h^(−1) M_⊙ at z = 1.4. Similar selection functions with only 80 per cent completeness threshold have also been computed. The complementarity of these results with selection functions for surveys in other bands is discussed

    Next Generation Cosmology: Constraints from the Euclid Galaxy Cluster Survey

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    We study the characteristics of the galaxy cluster samples expected from the European Space Agency's Euclid satellite and forecast constraints on cosmological parameters describing a variety of cosmological models. The method used in this paper, based on the Fisher Matrix approach, is the same one used to provide the constraints presented in the Euclid Red Book (Laureijs et al.2011). We describe the analytical approach to compute the selection function of the photometric and spectroscopic cluster surveys. Based on the photometric selection function, we forecast the constraints on a number of cosmological parameter sets corresponding to different extensions of the standard LambdaCDM model. The dynamical evolution of dark energy will be constrained to Delta w_0=0.03 and Delta w_a=0.2 with free curvature Omega_k, resulting in a (w_0,w_a) Figure of Merit (FoM) of 291. Including the Planck CMB covariance matrix improves the constraints to Delta w_0=0.02, Delta w_a=0.07 and a FoM=802. The amplitude of primordial non-Gaussianity, parametrised by f_NL, will be constrained to \Delta f_NL ~ 6.6 for the local shape scenario, from Euclid clusters alone. Using only Euclid clusters, the growth factor parameter \gamma, which signals deviations from GR, will be constrained to Delta \gamma=0.02, and the neutrino density parameter to Delta Omega_\nu=0.0013 (or Delta \sum m_\nu=0.01). We emphasise that knowledge of the observable--mass scaling relation will be crucial to constrain cosmological parameters from a cluster catalogue. The Euclid mission will have a clear advantage in this respect, thanks to its imaging and spectroscopic capabilities that will enable internal mass calibration from weak lensing and the dynamics of cluster galaxies. This information will be further complemented by wide-area multi-wavelength external cluster surveys that will already be available when Euclid flies. [Abridged]Comment: submitted to MNRA

    Optical coherence tomography in patients with chronic migraine: Literature review and update

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    Migraine is a chronic disease characterized by unilateral, pulsating, and often moderate-to-severe recurrent episodes of headache with nausea and vomiting. It affects approximately 15% of the general population, yet the underlying pathophysiological mechanisms are not fully understood. Optical coherence tomography (OCT) is a safe and reproducible diagnostic technique that utilizes infrared wavelengths and has a sensitivity of 8-10 µm. It can be used to measure thinning of the retinal nerve fiber layer (RNFL) in some neurological disorders. Although ophthalmologists are often the first specialists to examine patients with migraine, few studies have addressed the involvement of the optic nerve and retino-choroidal structures in this group. We reviewed the literature on the etiological and pathological mechanisms of migraine and the relationship between recurrent constriction of cerebral and retrobulbar vessels and ischemic damage to the optic nerve, retina, and choroid. We also assessed the role of OCT for measuring peripapillary RNFL thickness and macular and choroidal changes in migraine patients. There is considerable evidence of cerebral and retrobulbar vascular involvement in the etiology of migraine. Transitory and recurrent constriction of the retinal and ciliary arteries may cause ischemic damage to the optic nerve, retina, and choroid in patients with migraine. OCT to assess the thickness of the peripapillary RNFL, macula, and choroid might increase our understanding of the pathophysiology of migraine and facilitate diagnosis of retino-choroidal compromise and follow-up of therapy in migraine patients. Future studies should determine the usefulness of OCT findings as a biomarker of migraine

    The response to iron supplementation of pregnant women with the haemoglobin genotype AA or AS

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    The influence of haemoglobin genotype on the response to iron supplementation was studied in a randomized, double blind, placebo-controlled trial involving 497 multigravid pregnant women from a rural area of The Gambia. Women were randomly allocated to receive either oral iron (60mg elemental iron per day) or placebo. At 36 weeks of pregnancy, women who had received oral iron during pregnancy had higher mean haemoglobin, packed cell volume, plasma iron and ferritin levels than did women who received placebo. Iron supplementation of pregnant women with the AA haemoglobin genotype also resulted in increases in the packed cell volume (PCV) and haemoglobin level measured after delivery, and in the birth weight of the infant. However, in AS women PCV and haemoglobin level at delivery were lower in the supplemented group and supplementation was also associated with reduced birth weights. In malaria endemic areas, pregnant women with the haemoglobin genotype AS may not benefit from iron supplementation during pregnanc

    The evolution of Balmer jump selected galaxies in the ALHAMBRA survey

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    We present a new color-selection technique, based on the Bruzual & Charlot models convolved with the bands of the ALHAMBRA survey, and the redshifted position of the Balmer jump to select star-forming galaxies in the redshift range 0.5 < z < 1.5. These galaxies are dubbed Balmer jump Galaxies BJGs. We apply the iSEDfit Bayesian approach to fit each detailed SED and determine star-formation rate (SFR), stellar mass, age and absolute magnitudes. The mass of the haloes where these samples reside are found via a clustering analysis. Five volume-limited BJG sub-samples with different mean redshifts are found to reside in haloes of median masses ∼1012.5±0.2M⊙\sim 10^{12.5 \pm 0.2} M_\odot slightly increasing toward z=0.5. This increment is similar to numerical simulations results which suggests that we are tracing the evolution of an evolving population of haloes as they grow to reach a mass of ∼1012.7±0.1M⊙\sim 10^{12.7 \pm 0.1} M_\odot at z=0.5. The likely progenitors of our samples at z∼\sim3 are Lyman Break Galaxies, which at z∼\sim2 would evolve into star-forming BzK galaxies, and their descendants in the local Universe are elliptical galaxies.Hence, this allows us to follow the putative evolution of the SFR, stellar mass and age of these galaxies. From z∼\sim1.0 to z∼\sim0.5, the stellar mass of the volume limited BJG samples nearly does not change with redshift, suggesting that major mergers play a minor role on the evolution of these galaxies. The SFR evolution accounts for the small variations of stellar mass, suggesting that star formation and possible minor mergers are the main channels of mass assembly.Comment: 14 pages, 10 figures. Submitted to A&A. It includes first referee's comments. Abstract abridged due to arXiv requirement

    The ALHAMBRA survey: evolution of galaxy spectral segregation

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    We study the clustering of galaxies as a function of spectral type and redshift in the range 0.35<z<1.10.35 < z < 1.1 using data from the Advanced Large Homogeneous Area Medium Band Redshift Astronomical (ALHAMBRA) survey. The data cover 2.381 deg2^2 in 7 fields, after applying a detailed angular selection mask, with accurate photometric redshifts [σz<0.014(1+z)\sigma_z < 0.014(1+z)] down to IAB<24I_{AB} < 24. From this catalog we draw five fixed number density, redshift-limited bins. We estimate the clustering evolution for two different spectral populations selected using the ALHAMBRA-based photometric templates: quiescent and star-forming galaxies. For each sample, we measure the real-space clustering using the projected correlation function. Our calculations are performed over the range [0.03,10.0]h−1[0.03,10.0] h^{-1} Mpc, allowing us to find a steeper trend for rp≲0.2h−1r_p \lesssim 0.2 h^{-1} Mpc, which is especially clear for star-forming galaxies. Our analysis also shows a clear early differentiation in the clustering properties of both populations: star-forming galaxies show weaker clustering with evolution in the correlation length over the analysed redshift range, while quiescent galaxies show stronger clustering already at high redshifts, and no appreciable evolution. We also perform the bias calculation where similar segregation is found, but now it is among the quiescent galaxies where a growing evolution with redshift is clearer. These findings clearly corroborate the well known colour-density relation, confirming that quiescent galaxies are mainly located in dark matter halos that are more massive than those typically populated by star-forming galaxies.Comment: 14 pages, 9 figures, accepted by Ap

    An innovative quick solidifying technique for the forensic investigation of brain circulation using addition silicones

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    Post-mortem study of the brain is extremely relevant to medico-legal autopsies. However, it can be difficult to handle due to its fragility. This article presents a study on the development of an arterial solidifying technique that can be applied to analyze arterial circulation, consequently easing the handling and later diagnosis of diseases in this anatomical site. Vinylpolysiloxane silicone is introduced into the internal carotid arteries until it completely fills the arterial tree, creating a detailed model of the arterial's internal anatomy. This technique is fast, easy to apply and requires no previous tissue fixation. In addition, it allows for further toxicological and pathological tests. In conclusion, this technique represents a simple, sensitive and efficient method to employ in conventional autopsies, which can help in the diagnosis of death

    Gender differences in adaptation to heat in Spain (1983-2018)

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    In Spain the average temperature has increased by 1.7 °C since pre-industrial times. There has been an increase in heat waves both in terms of frequency and intensity, with a clear impact in terms of population health. The effect of heat waves on daily mortality presents important territorial differences. Gender also affects these impacts, as a determinant that conditions social inequalities in health. There is evidence that women may be more susceptible to extreme heat than men, although there are relatively few studies that analyze differences in the vulnerability and adaptation to heat by sex. This could be related to physiological causes. On the other hand, one of the indicators used to measure vulnerability to heat in a population and its adaptation is the minimum mortality temperature (MMT) and its temporal evolution. The aim of this study was to analyze the values of MMT in men and women and its temporal evolution during the 1983-2018 period in Spain's provinces. An ecological, longitudinal retrospective study was carried out of time series data, based on maximum daily temperature and daily mortality data corresponding to the study period. Using cubic and quadratic fits between daily mortality rates and the temperature, the minimum values of these functions were determined, which allowed for determining MMT values. Furthermore, we used an improved methodology that provided for the estimation of missing MMT values when polynomial fits were inexistent. This analysis was carried out for each year. Later, based on the annual values of MMT, a linear fit was carried out to determine the rate of evolution of MMT for men and for women at the province level. Average MMT for all of Spain's provinces was 29.4 °C in the case of men and 28.7 °C in the case of women. The MMT for men was greater than that of women in 86 percent of the total provinces analyzed, which indicates greater vulnerability among women. In terms of the rate of variation in MMT during the period analyzed, that of men was 0.39 °C/decade, compared to 0.53 °C/decade for women, indicating greater adaptation to heat among women, compared to men. The differences found between men and women were statistically significant. At the province level, the results show great heterogeneity. Studies carried out at the local level are needed to provide knowledge about those factors that can explain these differences at the province level, and to allow for incorporating a gender perspective in the implementation of measures for adaptation to high temperatures.The authors wish to thank the funding provided by the ENPY 304/20, ENPY 376/18 and ENPY 107/18 projects of the Carlos III Health Institute III (ISCIII). They also wish to thank the UNED for funding this publication in open access.S
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