The intrinsic dimensionality of spectro-polarimetric data

The amount of information available in spectro-polarimetric data is estimated. To this end, the intrinsic dimensionality of the data is inferred with the aid of a recently derived estimator based on nearest-neighbor considerations and obtained applying the principle of maximum likelihood. We show in detail that the estimator correctly captures the intrinsic dimension of artificial datasets with known dimension. The effect of noise in the estimated dimension is analyzed thoroughly and we conclude that it introduces a positive bias that needs to be accounted for. Real simultaneous spectro-polarimetric observations in the visible 630 nm and the near-infrared 1.5 microns spectral regions are also investigated in detail, showing that the near-infrared dataset provides more information of the physical conditions in the solar atmosphere than the visible dataset. Finally, we demonstrate that the amount of information present in an observed dataset is a monotonically increasing function of the number of available spectral lines.Comment: 12 pages, 7 figures, accepted for publication in the Astrophysical Journa

Stellar populations of galaxies in the ALHAMBRA survey up to z∼1z \sim 1. I. MUFFIT: A Multi-Filter Fitting code for stellar population diagnostics

We present MUFFIT, a new generic code optimized to retrieve the main stellar population parameters of galaxies in photometric multi-filter surveys, and we check its reliability and feasibility with real galaxy data from the ALHAMBRA survey. Making use of an error-weighted $\chi^2$-test, we compare the multi-filter fluxes of galaxies with the synthetic photometry of mixtures of two single stellar populations at different redshifts and extinctions, to provide through a Monte Carlo method the most likely range of stellar population parameters (mainly ages and metallicities), extinctions, redshifts, and stellar masses. To improve the diagnostic reliability, MUFFIT identifies and removes from the analysis those bands that are significantly affected by emission lines. We highlight that the retrieved age-metallicity locus for a sample of $z \le 0.22$ early-type galaxies in ALHAMBRA at different stellar mass bins are in very good agreement with the ones from SDSS spectroscopic diagnostics. Moreover, a one-to-one comparison between the redshifts, ages, metallicities, and stellar masses derived spectroscopically for SDSS and by MUFFIT for ALHAMBRA reveals good qualitative agreements in all the parameters. In addition, and using as input the results from photometric-redshift codes, MUFFIT improves the photometric-redshift accuracy by $\sim 10$-$20\%$, and it also detects nebular emissions in galaxies, providing physical information about their strengths. Our results show the potential of multi-filter galaxy data to conduct reliable stellar population studies with the appropiate analysis techniques, as MUFFIT.Comment: 31 pages, 18 figures, accepted for publication in A&

Improved constraints on the expansion rate of the Universe up to z~1.1 from the spectroscopic evolution of cosmic chronometers

We present new improved constraints on the Hubble parameter H(z) in the redshift range 0.15 < z < 1.1, obtained from the differential spectroscopic evolution of early-type galaxies as a function of redshift. We extract a large sample of early-type galaxies (\sim11000) from several spectroscopic surveys, spanning almost 8 billion years of cosmic lookback time (0.15 < z < 1.42). We select the most massive, red elliptical galaxies, passively evolving and without signature of ongoing star formation. Those galaxies can be used as standard cosmic chronometers, as firstly proposed by Jimenez & Loeb (2002), whose differential age evolution as a function of cosmic time directly probes H(z). We analyze the 4000 {\AA} break (D4000) as a function of redshift, use stellar population synthesis models to theoretically calibrate the dependence of the differential age evolution on the differential D4000, and estimate the Hubble parameter taking into account both statistical and systematical errors. We provide 8 new measurements of H(z) (see Tab. 4), and determine its change in H(z) to a precision of 5-12% mapping homogeneously the redshift range up to z \sim 1.1; for the first time, we place a constraint on H(z) at z \neq 0 with a precision comparable with the one achieved for the Hubble constant (about 5-6% at z \sim 0.2), and covered a redshift range (0.5 < z < 0.8) which is crucial to distinguish many different quintessence cosmologies. These measurements have been tested to best match a \Lambda CDM model, clearly providing a statistically robust indication that the Universe is undergoing an accelerated expansion. This method shows the potentiality to open a new avenue in constrain a variety of alternative cosmologies, especially when future surveys (e.g. Euclid) will open the possibility to extend it up to z \sim 2.Comment: 34 pages, 15 figures, 6 tables, published in JCAP. It is a companion to Moresco et al. (2012b, http://arxiv.org/abs/1201.6658) and Jimenez et al. (2012, http://arxiv.org/abs/1201.3608). The H(z) data can be downloaded at http://www.physics-astronomy.unibo.it/en/research/areas/astrophysics/cosmology-with-cosmic-chronometer

Stellar populations of bulges at low redshift

This chapter summarizes our current understanding of the stellar population properties of bulges and outlines important future research directions.Comment: Review article to appear in "Galactic Bulges", Editors: Laurikainen E., Peletier R., Gadotti D., Springer Publishing. 34 pages, 12 figure

ICAR: endoscopic skull‐base surgery

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The Nice Musical Chairs model : exploring the role of competition and cooperation between farming and herding in the formation of land use patterns in arid Afro-Eurasia [+ erratum]

Following a strictly theory-building approach, we developed an agent-based simulation model, the Nice Musical Chairs model, to represent the competition between groups of stakeholders of farming and herding activities in the arid Afro-Eurasia. The model deepens the questions raised by the results of our former model, the Musical Chairs model, and further introduces three socio-economic mechanisms, which modulate the behavior and performance of stakeholders and their groups. First, we define land use pairing as the awarding, regarding productivity, of any direct cooperation between farming and herding within a group. Second, group management is modeled as the prerogative of a group leadership to manage stakeholders to pursue a particular proportion between farming and herding. Third, we introduce restricted access to pasture as the engagement in territorial control of rangelands in opposition to an open access regime. An exhaustive exploration of scenarios and parameters placed the control over rangelands as the most significant factor in the formation of land use patterns, followed by land use management. While the effect of land use pairing is mild in comparison, it is still a significant factor in group selection and thus in the persistence of particular land use patterns in the long run

Inherited human ezrin deficiency impairs adaptive immunity

Inborn errors of immunity (IEI) are a group of monogenic diseases that confer susceptibility to infection, autoimmunity, and cancer. Despite the life-threatening consequences of some IEI, their genetic cause remains unknown in many patients. Objective: We investigated a patient with an IEI of unknown genetic etiology. Whole-exome sequencing identified a homozygous missense mutation of the gene encoding ezrin (EZR), substituting a threonine for an alanine at position 129. Ezrin is one of the subunits of the ezrin, radixin, and moesin (ERM) complex. The ERM complex links the plasma membrane to the cytoskeleton and is crucial for the assembly of an efficient immune response. The A129T mutation abolishes basal phosphorylation and decreases calcium signaling, leading to complete loss of function. Consistent with the pleiotropic function of ezrin in myriad immune cells, multidimensional immunophenotyping by mass and flow cytometry revealed that in addition to hypogammaglobulinemia, the patient had low frequencies of switched memory B cells, CD4 + and CD8 + T cells, MAIT, γδ T cells, and central naive CD4 + cells. Autosomal-recessive human ezrin deficiency is a newly recognized genetic cause of B-cell deficiency affecting cellular and humoral immunity

Multi-institutional expert update on the use of laparoscopic bile duct exploration in the management of choledocholithiasis: lesson learned from 3950 procedures

Background: Recently there has been a growing interest in the laparoscopic management of common bile duct stones with gallbladder in situ (LBDE), which is favoring the expansion of this technique. Our study identified the standardization factors of LBDE and its implementation in the single-stage management of choledocholithiasis. Methods: A retrospective multi-institutional study among 17 centers with proven experience in LBDE was performed. A cross-sectional survey consisting of a semi-structured pretested questionnaire was distributed covering the main aspects on the use of LBDE in the management of choledocholithiasis. Results: A total of 3950 LBDEs were analyzed. The most frequent indication was jaundice (58.8%). LBDEs were performed after failed ERCP in 15.2%. The most common approach used was the transcystic (63.11%). The overall series failure rate of LBDE was 4% and the median rate for each center was 6% (IQR, 4.5-12.5). Median operative time ranged between 60-120&nbsp;min (70.6%). Overall morbidity rate was 14.6%, with a postoperative bile leak and complications ≥3a rate of 4.5% and 2.5%, respectively. The operative time decreased with experience (P&nbsp;=.03) and length of hospital stay was longer in the presence of a biliary leak (P&nbsp;=.04). Current training of LBDE was defined as poor or very poor by 82.4%. Conclusion: Based on this multicenter survey, LBDE is a safe and effective approach when performed by experienced teams. The generalization of LBDE will be based on developing training programs

The legacy of Columbus in American horse populations assessed by microsatellite markers

Criollo horse populations descend from horses brought from the Iberian Peninsula over the period of colonization (15th to 17th century). They are spread throughout the Americas and have potentially undergone genetic hybridization with other breeds in the recent past. In this study, 25 autosomal microsatellites were genotyped in 50 horse breeds representing Criollo populations from 12 American countries (27 breeds), breeds from the Iberian Peninsula (19), one breed each from France and Morocco and two cosmopolitan horse breeds (Thoroughbred and Arabian). The genetic relationships among breeds identified five clusters: Celtic; Iberian; North American with Thoroughbred influence; most Colombian breeds; and nearly all other Criollo breeds. The group of “all other Criollo breeds” had the closest genetic relationship with breeds originating from the Iberian Peninsula, specifically with the Celtic group. For the whole set of Criollo breeds analysed, the estimated genetic contribution from other breeds was approximately 50%, 30% and 20% for the Celtic, Iberian and Arab-Thoroughbred groups, respectively. The spatial distribution of genetic diversity indicates that hotspots of genetic diversity are observed in populations from Colombia, Ecuador, Brazil, Paraguay and western United States, possibly indicating points of arrival and dispersion of Criollo horses in the American continent. These results indicate that Criollo breeds share a common ancestry, but that each breed has its own identity