The distribution of two-dimensional eccentricity of Sunyaev-Zeldovich Effect and X-ray surface brightness profiles

With the triaxial density profile of dark matter halos and the corresponding equilibrium gas distribution, we derive two-dimensional Sunyaev-Zeldovich (SZ) effect and X-ray surface brightness profiles for clusters of galaxies. It is found that the contour map of these observables can be well approximated by a series of concentric ellipses with scale-dependent eccentricities. The statistical distribution of their eccentricities (or equivalently axial ratios) is analyzed by taking into account the orientation of clusters with respect to the line of sight and the distribution of the axial ratios and the concentration parameters of dark matter halos. For clusters of mass $10^{13}h^{-1}{M}_{\odot}$ at redshift $z=0$, the axial ratio is peaked at $\eta \sim 0.9$ for both SZ and X-ray profiles. For larger clusters, the deviation from circular distributions is more apparent, with $\eta$ peaked at $\eta \sim 0.85$ for $M=10^{15}h^{-1}{M}_{\odot}$. To be more close to observations, we further study the axial-ratio distribution for mass-limited cluster samples with the number distribution of clusters at different redshifts described by a modified Press-Schechter model. For a mass limit of value $M_{lim}=10^{14}h^{-1}{M}_{\odot}$, the average axial ratio is $\sim 0.84$ with a tail extended to $\eta \sim 0.6$. With fast advance of high quality imaging observations of both SZ effect and X-ray emissions, our analyses provide a useful way to probe cluster halo profiles and therefore to test theoretical halo-formation models.Comment: 28 pages, 6 figures. Accepted for publication in the Astrophysical Journa

Simulation of primordial object formation

We have included the chemical rate network responsible for the formation of molecular Hydrogen in the N-body hydrodynamic code, Hydra, in order to study the formation of the first cosmological at redshifts between 10 and 50. We have tested our implementation of the chemical and cooling processes by comparing N-body top hat simulations with theoretical predictions from a semi-analytic model and found them to be in good agreement. We find that post-virialization properties are insensitive to the initial abundance of molecular hydrogen. Our main objective was to determine the minimum mass ($M_{SG}(z)$) of perturbations that could become self gravitating (a prerequisite for star formation), and the redshift at which this occurred. We have developed a robust indicator for detecting the presence of a self-gravitating cloud in our simulations and find that we can do so with a baryonic particle mass-resolution of 40 solar masses. We have performed cosmological simulations of primordial objects and find that the object's mass and redshift at which they become self gravitating agree well with the $M_{SG}(z)$ results from the top hat simulations. Once a critical molecular hydrogen fractional abundance of about 0.0005 has formed in an object, the cooling time drops below the dynamical time at the centre of the cloud and the gas free falls in the dark matter potential wells, becoming self gravitating a dynamical time later.Comment: 45 pages, 17 figures, submitted to Ap

Pro-oxidant effect of ALA is implicated in mitochondrial dysfunction of HepG2 cells

Heme biosynthesis begins in the mitochondrion with the formation of delta-aminolevulinic acid (ALA). In acute intermittent porphyria, hereditary tyrosinemia type I and lead poisoning patients, ALA is accumulated in plasma and in organs, especially the liver. These diseases are also associated with neuromuscular dysfunction and increased incidence of hepatocellular carcinoma. Many studies suggest that this damage may originate from ALA-induced oxidative stress following its accumulation. Using the MnSOD as an oxidative stress marker, we showed here that ALA treatment of cultured cells induced ROS production, increasing with ALA concentration. The mitochondrial energetic function of ALA-treated HepG2 cells was further explored. Mitochondrial respiration and ATP content were reduced compared to control cells. For the 300 μM treatment, ALA induced a mitochondrial mass decrease and a mitochondrial network imbalance although neither necrosis nor apoptosis were observed. The up regulation of PGC-1, Tfam and ND5 genes was also found; these genes encode mitochondrial proteins involved in mitochondrial biogenesis activation and OXPHOS function. We propose that ALA may constitute an internal bioenergetic signal, which initiates a coordinated upregulation of respiratory genes, which ultimately drives mitochondrial metabolic adaptation within cells. The addition of an antioxidant, Manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), resulted in improvement of maximal respiratory chain capacity with 300 μM ALA. Our results suggest that mitochondria, an ALA-production site, are more sensitive to pro-oxidant effect of ALA, and may be directly involved in pathophysiology of patients with inherited or acquired porphyria

Las estructuras resistentes en la configuración de espacios habitables

Buscando aportar a superar la escisión entre conocimientos científico-técnicos y conocimientos proyectuales, muy generalizada en la formación de los arquitectos, desarrollamos sintéticamente los fundamentos conceptuales del enfoque integrador de arquitectura/estructura con el que llevamos adelante la formación en la materia Estructuras Resistentes 1, 2 y 3, a partir de entender el diseño estructural como problema de proyecto arquitectónico.Área Docencia - Eje 1 Innovación en sistemas constructivos/estructuralesFacultad de Arquitectura y Urbanism

The Impact of HD Cooling on the Formation of the First Stars

We use numerical simulations to investigate the importance of HD formation and cooling on the first generation of metal-free stars in a LCDM cosmology. We have implemented and tested non-equilibrium HD chemistry in an adaptive mesh refinement simulation code and applied it to two situations. (1) It is first applied to the formation of 10^5 - 10^6 Msun halos which form in the absence of any ionizing source. We show, in agreement with previous work, that HD cooling is of only marginal importance for most halos; however, we find that for the lowest mass halos, HD cooling can equal or surpass the H2 cooling rate. This leads to a population of stars formed in halos with effective HD cooling that are less massive by a factor of ~6 compared to halos dominated by H2 cooling. (2) In the second part of the paper, we ionize the halos in order to explore the impact of HD cooling in the presence of an ample population of free electrons. This leads to cooler temperatures (due to the electron- catalyzed production of H2) and somewhat lower resulting proto-stellar mass. Adding HD chemistry lowers the temperature further, to the level of the CMB. We find that HD cooling dominates over H2 cooling in the density range 10^2 cm^-3 to 10^6 cm^-3, but above this density, the temperature rises and H2 cooling dominates again. Because of this, the accretion rate on to the protostar is almost the same as in the H2 case (at least for accreted masses below 50-100 Msun), therefore we argue that HD cooling in ionized halos will probably not result in a population of significantly lower mass stars.Comment: 13 pages, 11 figures, with referee suggestions; ApJ accepte

Las estructuras resistentes en la configuración de espacios habitables

Buscando aportar a superar la escisión entre conocimientos científico-técnicos y conocimientos proyectuales, muy generalizada en la formación de los arquitectos, desarrollamos sintéticamente los fundamentos conceptuales del enfoque integrador de arquitectura/estructura con el que llevamos adelante la formación en la materia Estructuras Resistentes 1, 2 y 3, a partir de entender el diseño estructural como problema de proyecto arquitectónico.Área Docencia - Eje 1 Innovación en sistemas constructivos/estructuralesFacultad de Arquitectura y Urbanism

Las estructuras resistentes en la configuración de espacios habitables

Buscando aportar a superar la escisión entre conocimientos científico-técnicos y conocimientos proyectuales, muy generalizada en la formación de los arquitectos, desarrollamos sintéticamente los fundamentos conceptuales del enfoque integrador de arquitectura/estructura con el que llevamos adelante la formación en la materia Estructuras Resistentes 1, 2 y 3, a partir de entender el diseño estructural como problema de proyecto arquitectónico.Área Docencia - Eje 1 Innovación en sistemas constructivos/estructuralesFacultad de Arquitectura y Urbanism