74 research outputs found
A semi-analytical perspective on massive galaxies at
The most massive and luminous galaxies in the Universe serve as powerful
probes to study the formation of structure, the assembly of mass, and
cosmology. However, their detailed formation and evolution is still barely
understood. Here we extract a sample of massive mock galaxies from the
semi-analytical model of galaxy formation (SAM) GALACTICUS from the
MultiDark-Galaxies, by replicating the CMASS photometric selection from the
SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS). The comparison of the
GALACTICUS CMASS-mock with BOSS-CMASS data allows us to explore different
aspects of the massive galaxy population at , including the
galaxy-halo connection and the galaxy clustering. We find good agreement
between our modelled galaxies and observations regarding the galaxy-halo
connection, but our CMASS-mock over-estimates the clustering amplitude of the
2-point correlation function, due to a smaller number density compared to BOSS,
a lack of blue objects, and a small intrinsic scatter in stellar mass at fixed
halo mass of dex. To alleviate this problem, we construct an alternative
mock catalogue mimicking the CMASS colour-magnitude distribution by randomly
down-sampling the SAM catalogue. This CMASS-mock reproduces the clustering of
CMASS galaxies within 1 and shows some environmental dependency of star
formation properties that could be connected to the quenching of star formation
and the assembly bias.Comment: 15 pages, 10 figures, 2 tables, submitted to MNRA
The Cosmic Web from Perturbation Theory
Context: Analyzing the large-scale structure (LSS) with galaxy surveys
demands accurate structure formation models. Such models should ideally be fast
and have a clear theoretical framework to rapidly scan a variety of
cosmological parameter spaces without requiring large training data sets. Aims:
This study aims to extend Lagrangian perturbation theory (LPT), including
viscosity and vorticity, to reproduce the cosmic evolution from dark matter
N-body calculations at the field level. Methods: We extend LPT to an Eulerian
framework, dubbed eALPT. An ultraviolet regularisation through the spherical
collapse model provided by Augmented LPT, turns out to be crucial at low
redshifts. This enables modelling the stress tensor, with this introducing
vorticity. The model has two free parameters apart from the choice of
cosmology, redshift snapshots, cosmic volume, and the number of
particles-cells. Results: We find that the cross-correlation of the dark matter
distribution as compared to N-body solvers increases at Mpc
and from 55\% with the Zel'dovich approximation (70\% with
ALPT), to 95\% with three timesteps eALPT, and power spectra within
percentage accuracy up to Mpc.Comment: 6 pages, 3 figure
MHC class I-related antigen-processing machinery component defects in feline mammary carcinoma.
Defects in HLA class I antigen-processing machinery (APM) component expression and/or function are frequent in human tumors. These defects may provide tumor cells with a mechanism to escape from recognition and destruction by HLA class I antigen-restricted, tumor antigen-specific cytotoxic T cells. However, expression and functional properties of MHC class I antigens and APM components in malignant cells in other animal species have been investigated to a limited extent. However, this information can contribute to our understanding of the mechanisms underlying the association of MHC class I antigen and APM component defects with malignant transformation of cells and to identify animal models to validate targeted therapies to correct these defects. To overcome this limitation in the present study, we have investigated the expression of the catalytic subunits of proteasome (Y, X, and Z) and of immunoproteasome (LMP2, LMP7, and LMP10) as well as of MHC class I heavy chain (HC) in 25 primary feline mammary carcinomas (FMCs) and in 23 matched healthy mammary tissues. We found a reduced expression of MHC class I HC and of LMP2 and LMP7 in tumors compared with normal tissues. Concordantly, proteasomal cleavage specificities in extracts from FMCs were different from those in healthy tissues. In addition, correlation analysis showed that LMP2 and LMP7 were concordantly expressed in FMCs, and their expression was significantly correlated with that of MHC class I HC. The abnormalities we have found in the APM in FMCs may cause a defective processing of some tumor antigens
Viral load, tissue distribution and histopathological lesions in goats naturally and experimentally infected with the Small Ruminant Lentivirus Genotype E (subtype E1 Roccaverano strain)
Small Ruminant Lentivirus (SRLV) subtype E1, also known as Roccaverano strain, is considered a low pathogenic virus on the basis of natural genetic deletions, in vitro properties and on-farm observations. In order to gain more knowledge on this atypical lentivirus we investigated the in vivo tropism of Roccaverano strain in both, experimentally and naturally infected goats. Antibody responses were monitored as well as tissue distribution and viral load, evaluated by real time PCR on single spliced (gag/env) and multiple spliced (rev) RNA targets respectively, that were compared to histopathological lesions. Lymph nodes, spleen, alveolar macrophages and mammary gland turned out to be the main tissue reservoirs of genotype E1-provirus. Moreover, mammary gland and/or mammary lymph nodes acted as active replication sites in dairy goats, supporting the lactogenic transmission of this virus. Notably, a direct association between viral load and concomitant infection or inflammatory processes was evident within organs such as spleen, lung and testis.
Our results validate the low pathogenicity designation of SRLV genotype E1 in vivo, and confirm the monocyte-macrophage cell lineage as the main virus reservoir of this genotype. Accordingly, SRLV genotype E displays a tropism towards all tissues characterized by an abundant presence of these cells, either for their own anatomical structure or for an occasional infectious/inflammatory status.This work was co-funded by the Italian Ministry of Instruction, University and Research PRIN 2008 (no. 20084CSFLT), by Piedmont Region, “Ricerca Sanitaria Finalizzata” 2008 and 2009, and by University of Turin, “Fondi ricerca locale (ex-60%)” 2009. The Authors acknowledge Mr. R. Maritano, CISRA for his valuable contribution in animal management, and Mr. D. Arnulfo and R. Vanni for their competent work and assistance during animal autopsies.
R. Reina was supported by Spanish Ministry of Science and Innovation ‘Ramón y Cajal’ contract (AGL2013-49137-C3-1R).Peer reviewe
SkyPy: A package for modelling the Universe
SkyPy is an open-source Python package for simulating the astrophysical sky. It comprises
a library of physical and empirical models across a range of observables and a command line
script to run end-to-end simulations. The library provides functions that sample realisations
of sources and their associated properties from probability distributions. Simulation pipelines
are constructed from these models using a YAML-based configuration syntax, while task
scheduling and data dependencies are handled internally and the modular design allows users
to interface with external software. SkyPy is developed and maintained by a diverse community
of domain experts with a focus on software sustainability and interoperability. By fostering
co-development, it provides a framework for correlated simulations of a range of cosmological
probes including galaxy populations, large scale structure, the cosmic microwave background,
supernovae and gravitational waves.
Version 0.4 implements functions that model various properties of galaxies including luminosity functions, redshift distributions and optical photometry from spectral energy distribution
templates. Future releases will provide additional modules, for example to simulate populations of dark matter halos and model the galaxy-halo connection, making use of existing
software packages from the astrophysics community where appropriate
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: modelling the clustering and halo occupation distribution of BOSS CMASS galaxies in the Final Data Release
Citation: Rodriguez-Torres, S. A., Chuang, C. H., Prada, F., Guo, H., Klypin, A., Behroozi, P., . . . Thomas, D. (2016). The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: modelling the clustering and halo occupation distribution of BOSS CMASS galaxies in the Final Data Release. Monthly Notices of the Royal Astronomical Society, 460(2), 1173-1187. doi:10.1093/mnras/stw1014We present a study of the clustering and halo occupation distribution of Baryon Oscillation Spectroscopic Survey (BOSS) CMASS galaxies in the redshift range 0.43 cold dark matter Planck cosmology. We compare the observational data with the simulated ones on a light cone constructed from 20 subsequent outputs of the simulation. Observational effects such as incompleteness, geometry, veto masks and fibre collisions are included in the model, which reproduces within 1 sigma errors the observed monopole of the two-point correlation function at all relevant scales: from the smallest scales, 0.5 h(-1) Mpc, up to scales beyond the baryon acoustic oscillation feature. This model also agrees remarkably well with the BOSS galaxy power spectrum (up to k similar to 1 h Mpc(-1)), and the three-point correlation function. The quadrupole of the correlation function presents some tensions with observations. We discuss possible causes that can explain this disagreement, including target selection effects. Overall, the standard HAM model describes remarkably well the clustering statistics of the CMASS sample. We compare the stellar-to-halo mass relation for the CMASS sample measured using weak lensing in the Canada-France-Hawaii Telescope Stripe 82 Survey with the prediction of our clustering model, and find a good agreement within 1 sigma. The BigMD-BOSS light cone including properties of BOSS galaxies and halo properties is made publicly available
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