Fossil groups in the Millennium simulation. From the brightest to the faintest galaxies during the past 8 Gyr

We investigate the evolution of bright and faint galaxies in fossil and non-fossil groups. We used mock galaxies constructed based on the Millennium run simulation II. We identified fossil groups at redshift zero according to two different selection criteria, and then built reliable control samples of non-fossil groups that reproduce the fossil virial mass and assembly time distributions. The faint galaxies were defined as having r-band absolute magnitudes in the range [-16,-11]. We analysed the properties of the bright and faint galaxies in fossil and non-fossil groups during the past 8 Gyr. We observed that the brightest galaxy in fossil groups is typically brighter and more massive than their counterparts in control groups. Fossil groups developed their large magnitude gap between the brightest galaxies around 3.5 Gyr ago. The brightest galaxy stellar masses of all groups show a notorious increment at that time. By analysing the behaviour of the magnitude gap between the first and the second, third, and fourth ranked galaxies, we found that at earlier times, fossil groups comprised two large brightest galaxies with similar magnitudes surrounded by much fainter galaxies, while in control groups these magnitude gaps were never as large as in fossils. At early times, fossil groups in the faint population were denser than non-fossil groups, then this trend reversed, and finally they became similar at the present day. The mean number of faint galaxies in non-fossil systems increases in an almost constant rate towards later times, while this number in fossil groups reaches a plateau at $z\sim0.6$ that lasts $\sim 2$ Gyr, and then starts growing again more rapidly. The formation of fossil groups is defined at the very beginning of the groups according to their galaxy luminosity sampling, which could be determined by their merging rate at early times.Comment: 10 pages, 6 figures, 1 table. Accepted for publication in Astronomy & Astrophysic

On the properties of compact groups identified in different photometric bands

Historically, compact group catalogues vary not only in their identification algorithms and selection functions, but also in their photometric bands. Differences between compact group catalogues have been reported. However, it is difficult to assess the impact of the photometric band in these differences given the variety of identification algorithms. We used the mock lightcone built by Henriques et al. (2012) to identify and compare compact groups in three different photometric bands: $K$, $r$, and $u$. We applied the same selection functions in the three bands, and found that compact groups in the u-band look the smallest in projection, the difference between the two brightest galaxies is the largest in the K-band, while compact groups in the r-band present the lowest compactness. We also investigated the differences between samples when galaxies are selected only in one particular band (pure compact groups) and those that exist regardless the band in which galaxies were observed (common compact groups). We found that the differences between the total samples are magnified, but also some others arise: pure-r compact groups are the largest in projection; pure-u compact groups have the brightest first ranked galaxies, and the most similar two first ranked galaxies; pure-K compact groups have the highest compactness and the most different two first ranked galaxies; and common compact groups show the largest percentage of physically dense groups. Therefore, without a careful selection and identification of the samples, the characteristic features of group properties in a particular photometric band could be overshadowed.Comment: 9 pages, 3 figures, 5 tables. Accepted for publication in MNRA

Percolation on patchwise heterogeneous surfaces under equilibrium conditions

The site percolation problem on square lattices whose sites are grouped in two types of energetically different patches is studied. Several lattices formed by collections of either randomly or orderly localized and no overlapped patches of different sizes are generated. The system is characterized by two parameters, namely, the size of each patch, l, and the energy difference between the two kind of sites, E. Particles are adsorbed at equilibrium on the lattice. The critical coverage is determined by means of Monte Carlo simulations and finite-size scaling analysis. The percolative behavior of the system as a function of the parameters characterizing the heterogeneity of the energetic surface topography is presented and discussed.Fil: Gimenez, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Física Enrique Gaviola. Universidad Nacional de Córdoba. Instituto de Física Enrique Gaviola; ArgentinaFil: Ramirez Pastor, Antonio Jose. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Nieto Quintas, Felix Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; Argentin

Coronavirus disease 2019 in chronic kidney disease

The clinical spectrum of coronavirus disease 2019 (COVID-19) infection ranges from asymptomatic infection to severe pneumonia with respiratory failure and even death. More severe cases with higher mortality have been reported in older patients and in those with chronic illness such as hypertension, diabetes or cardiovascular diseases. In this regard, patients with chronic kidney disease (CKD) have a higher rate of all-type infections and cardiovascular disease than the general population. A markedly altered immune system and immunosuppressed state may predispose CKD patients to infectious complications. Likewise, they have a state of chronic systemic inflammation that may increase their morbidity and mortality. In this review we discuss the chronic immunologic changes observed in CKD patients, the risk of COVID-19 infections and the clinical implications for and specific COVID-19 therapy in CKD patients. Indeed, the risk for severe COVID-19 is 3-fold higher in CKD than in non-CKD patients; CKD is 12-fold more frequent in intensive care unit than in non-hospitalized COVID-19 patients, and this ratio is higher than for diabetes or cardiovascular disease; and acute COVID19 mortality is 15-25% for haemodialysis patients even when not developing pneumonia

Quantification and qualification of dead wood in a forest of Semiarid Chaco

Las evaluaciones cualitativas y cuantitativas del material biológico muerto son utilizadas en los inventarios forestales, dado que juegan un papel clave en el ciclo de nutrientes y agua, constituyendo un verdadero indicador de biodiversidad, reserva de carbono y sustrato. El objetivo del trabajo fue cuantificar, calificar y evaluar el volumen y grado de deterioro de la madera muerta en un bosque bajo clausura de 20 años del Chaco Semiárido. El estudio se realizó en Quimilí Paso, Departamento Salavina, Santiago del Estero, Argentina. Sobre la base de un inventario forestal estratificado, se determinó las existencias del sitio mediante parcelas rectangulares de 10x100m. Se estudió la madera muerta en base a: calificación según posición en el terreno (árboles muertos en pie, troncos caídos y tocones) y diámetro del leño (grueso diámetro>2,5cm; fino diámetro2.5 cm, slim when diameter <2.5 cm, standing dead trees diameter and stump diameter); and quantification from the volume of firewood, and determination of the deterioration extent based on 5 states (I, bark keeps fixed; II, bark peels and remains 50%; III, bark peels but remains less than 50%; IV, without bark the trunk breaks easily; V, most of the trunk is sawdust). The estimated deadwood volume is 7 m3 /ha. Of the total quantified volume, 66% corresponds to standing dead trees. The Acacia praecox and Prosopis ruscifolia are the most representative species that comprise 49% and 24% of that volume. This study lays the foundation for further research on the importance of dead wood in the Semiarid Chaco.Fil: Diaz Zirpolo, Jose Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Santiago del Estero. Facultad de Ciencias Forestales; ArgentinaFil: Gimenez, Ana Maria Isabel. Universidad Nacional de Santiago del Estero. Facultad de Ciencias Forestales; Argentin

Comparative wood anatomy of tree native species of Schinopsis (Anacardiaceae)

Schinopsis, género endémico de Sudamérica, incluye ocho especies que habitan en los bosques xerófilos chaqueños de Argentina, Bolivia, Paraguay y Brasil. Son cuatro las especies nativas de Argentina, dos de gran importancia económica. El objetivo del trabajo es comparar anatómicamente el xilema de: S. lorentzii (Griseb.) Engl., S. balansae Engl. y Schinopsis marginata Engl. Se trabajó con 5 árboles por especie. Se usó la terminología del Comité de Nomenclatura de IAWA y Tortorelli en las descripciones. Se utilizaron los índices de vulnerabilidad y mesomorfía propuestos por Carlquist para determinar el tipo de comportamiento. Se analizó comparativamente los rasgos anatómicos relevantes. Se analizaron estadísticamente cinco variables cuantitativas: frecuencia de poros/mm2 (Fv); diámetro tangencial (Vd) y longitud de los elementos vasculares (VI); altura del radio (Rh). El leño homogéneo, presenta diferencias en las variables cuantitativas como frecuencia, diámetro y longitud de vaso. El rasgo anatómico predominante es la presencia de canales secretores de tanino radiales y vasos del duramen ocluidos por tilosis. Los leños de S. lorentzii y S. marginata mostraron gran afinidad y rasgos mesofiticos con tendencia a xerofíticos; mientras que S. balansae presenta signos mesofíticos.Schinopsis, endemic genus of South America, includes eight species that inhabit the Chaco dry forests of Argentina, Bolivia, Paraguay and Brazil. Four species are native to Argentina; two of great economic importance. The aim of this work is to perform comparative wood anatomy of S. lorentzii, S. balansae and S. marginata. It worked with 5 trees of each species. The terminology of IAWA Committee on Nomenclature and Tortorelli were used in wood descriptions. Vulnerability and mesomorphy index proposed by Carlquist, to determine the type of behavior, were used. Relevant anatomical features were comparatively analyzed. Five variables were statistically analyzed: vessel frequency/ mm2 (Fv); tangential vessel diameter (Vd); length of vascular elements (VI) and ray height (Rh). The anatomy of wood is homogeneous, with significant differences in the variables: frequency, diameter and vessel length. Secretory radial tannin channels and tilosis occluding vessel, are predominant anatomical features. Wood anatomy of S. lorentzii and S. marginata showed high affinity and mesophitic to xeric trait; while S. balansae presents mesophitic signs.Fil: Gimenez, Ana Maria Isabel. Universidad Nacional de Santiago del Estero. Facultad de Ciencias Forestales. Instituto de Silvicultura y Manejo de Bosques; ArgentinaFil: Calatayu, Federico. Universidad Nacional de Santiago del Estero. Facultad de Ciencias Forestales; ArgentinaFil: Diaz Zirpolo, Jose Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Figueroa, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gonzalez, Damian. Fondo para la Investigación Científica y Tecnológica; Argentin

Novel Ideal Nonimaging Designs by Multichanneling the Phase-Space Flow

New ultra-thin optical designs are presented. They are formed by optical sections (called channels) working in parallel (multichanneling) to provide the desired optical function. The phase-space representation of the bundle of rays going from the source to the target is discontinuous between channels. This phase-space ray-bundle flow is divided in as many branches as channels there are but it is a single trunk at the source and at the target. Typically, these multichannel devices are at least formed by three optical surfaces: two of them have discontinuities (in the shape or in the shape derivative) while the last one is smooth. The discontinuities of the optical surfaces are causing the separation of the flow in branches (in the phase space). The number of discontinuities is the same in the two first surfaces: Each channel is defined by the smooth surfaces in between discontinuities, so the surfaces forming each separate channel are all smooth. No diffractive analysis is don

Overview of the SMS design method applied to imaging optics

The Simultaneous Multiple Surfaces (SMS) was developed as a design method in Nonimaging Optics during the 90s. Later, the method was extended for designing Imaging Optics. We present an overview of the method applied to imaging optics in planar (2D) geometry and compare the results with more classical designs based on achieving aplanatism of different orders. These classical designs are also viewed as particular cases of SMS designs. Systems with up to 4 aspheric surfaces are shown. The SMS design strategy is shown to perform always better than the classical design (in terms of image quality). Moreover, the SMS method is a direct method, i.e., it is not based in multi-parametric optimization techniques. This gives the SMS method an additional interest since it can be used for exploring solutions where the multiparameter techniques can get lost because of the multiple local minim