483 research outputs found
How do galaxies populate haloes in high-density environments? An analysis of the Halo Occupation Distribution in future virialized structures
There are hints suggesting that properties of galaxy populations in dark
matter haloes may depend on their large-scale environment. Recent works point
out that very low-density environments influence halo occupation distribution
(HOD), however there is not a similar analysis focused on high-density
environments. Here we use a simulated set of future virialized superstructures
(FVS) to analyse the occupation of galaxies in haloes within these high
globally dense regions.
We use a publicly available simulated galaxy set constructed with a
semi-analytical model to identify FVS in the simulation. Then, we computed the
HOD within these superstructures for different absolute magnitude thresholds
and make several analysis including the comparison to the global HOD results.
We study the dependence on the results on properties of the FVS such as density
and volume as well as consider the morphology of galaxies. We also analysed the
properties of the stellar content of galaxies and the formation time of the
haloes inside FVS.
We find a significant increase in the HOD inside FVS. This result is present
for all absolute magnitude thresholds explored. The effect is larger in the
densest regions of FVS, but does not depend on the volume of the
superstructure. We also find that the stellar-mass content of galaxies
considerably differs inside the superstructures. Low mass haloes have their
central and satellite galaxies with a higher stellar mass content (50%), and
exhibit mean star ages (20%) older than average. For massive haloes in FVS we
find that only the stellar mass of satellite galaxies varies considerably
corresponding to a decrease of 50%. We find a significant statistical
difference between the formation times of haloes in FVS and the average
population. Haloes residing in superstructures formed earlier, a fact that
leads to several changes in the HOD and their member galaxy properties.Comment: 12 pages, 14 figures, the paper has been accepted to be published by
the A&
Calibration of semi-analytic models of galaxy formation using Particle Swarm Optimization
We present a fast and accurate method to select an optimal set of parameters
in semi-analytic models of galaxy formation and evolution (SAMs). Our approach
compares the results of a model against a set of observables applying a
stochastic technique called Particle Swarm Optimization (PSO), a self-learning
algorithm for localizing regions of maximum likelihood in multidimensional
spaces that outperforms traditional sampling methods in terms of computational
cost. We apply the PSO technique to the SAG semi-analytic model combined with
merger trees extracted from a standard CDM N-body simulation. The
calibration is performed using a combination of observed galaxy properties as
constraints, including the local stellar mass function and the black hole to
bulge mass relation. We test the ability of the PSO algorithm to find the best
set of free parameters of the model by comparing the results with those
obtained using a MCMC exploration. Both methods find the same maximum
likelihood region, however the PSO method requires one order of magnitude less
evaluations. This new approach allows a fast estimation of the best-fitting
parameter set in multidimensional spaces, providing a practical tool to test
the consequences of including other astrophysical processes in SAMs.Comment: 11 pages, 4 figures, 1 table. Accepted for publication in ApJ.
Comments are welcom
Immunization with a tumor-associated CTL epitope plus a tumor-related or unrelated Th1 helper peptide elicits protective CTL immunity
Immunization with cytotoxic T cell epitope SPSYVYHQF (AH1), derived from MuLV gp70 envelope protein expressed by CT26 tumor cells, does not protect BALB/c mice against challenge with CT26 tumor cells. By contrast, immunization with AH1 plus T helper peptides OVA(323-337) or SWM(106-118) eliciting Th1 and Th0 profiles, protected 83% and 33% of mice, respectively. Interestingly, immunization with AH1 plus both helper peptides reverted the efficacy to 33%. We identified the endogenous T helper peptide p(320-333) from gp70 which elicits a Th1 profile and is naturally processed. As for OVA(323-337), immunization with p(320-333) alone did not protect against tumor challenge. However, p(320-333) plus AH1 protected 89% of mice at day 10 after vaccination. Only 20% of mice vaccinated with AH1 + OVA(323-337) or AH1 + p(320-333) were protected when challenged 80 days after immunization. Treatment with OVA(323-337) or with p(320-333) around established tumors delayed tumor growth. Our results show that tumor-related as well as tumor-unrelated but strong Th1 peptides may be useful for inducing CTL responses in tumor immunotherapy
A novel ammoniation treatment of barley as a strategy to optimize rumen pH, feed degradability and microbial protein synthesis in sheep
Background:
Meeting the energy and nitrogen requirements of high‐performing ruminants while avoiding digestive disturbances (i.e. rumen acidosis) is a key priority in ruminant nutrition. This study evaluated the effect of a cereal ammoniation treatment, in which barley grains are combined with urea and enzymes that catalyze the conversion of urea to ammonia to optimize rumen function. Twelve rumen cannulated sheep were randomly divided in two groups and fed a diet containing 60% of ammoniated barley (AMM), or untreated barley supplemented with urea (CTL) to study the impact on rumen fermentation and feed utilization.
Results:
Ammoniated barley had higher total N content and effective rumen degradable N than untreated barely. AMM sheep had a consistently higher rumen pH throughout the day (6.31 vs 6.03) and tended to have a lower post‐prandial ammonia peak and higher acetate molar proportion (+5.1%) than CTL sheep. The rumen environment in AMM sheep favored the colonization and utilization of agro‐industrial by‐products (i.e. orange pulp) by the rumen microbes leading to a higher feed degradability. AMM sheep also had higher total tract apparent N digestibility (+21.7%) and urinary excretion of purine derivatives (+34%) suggesting higher N uptake and microbial protein synthesis than CTL sheep.
Conclusions:
The inclusion of ammoniated barley in ruminants’ diet represents a valid strategy to maintain rumen pH within a physiological range and to improve N utilization by the rumen microbes which could have positive effects on animal's health and productivity in intensive production systems. These findings warrant further studies under conventional farm conditions
Realistic spectral function model for charged-current quasielastic-like neutrino and antineutrino scattering cross sections on 12C
A detailed study of charged current quasielastic neutrino and antineutrino scattering cross sections on a 12C
target with no pions in the final state is presented. The initial nucleus is described by means of a realistic spectral
function S(p, E) in which nucleon-nucleon correlations are implemented by using natural orbitals through
the Jastrow method. The roles played by these correlations and by final-state interactions are analyzed and
discussed. The model also includes the contribution of weak two-body currents in the two-particle two-hole
sector, evaluated within a fully relativistic Fermi gas. The theoretical predictions are compared with a large
set of experimental data for double-differential, single-differential, and total integrated cross sections measured
by the MiniBooNE, MINERνA, and T2K experiments. Good agreement with experimental data is found over
the whole range of neutrino energies. The results are also in global good agreement with the predictions of
the superscaling approach, which is based on the analysis of electron-nucleus scattering data, with only a few
differences seen at specific kinematics.This work was partially supported by the Bulgarian National
Science Fund under Contracts No. DFNI-T02/19,
No. DFNI-E02/6, and No. DNTS/Russia 01/3; by the Russian
Foundation for Basic Research Grant No. 17-52-18057-bolga;
by the Spanish Ministerio de Economia y Competitividad
and ERDF (European Regional Development Fund) under
Contracts No. FIS2014-59386-P, No. FIS2014-53448-C2-
1, No. FIS2017-88410-P, No. FIS2017-85053-C2-1-P, and
No. FPA2015-65035-P; by the Junta de Andalucia (Grants
No. FQM-225, FQM160); by the INFN under project MANYBODY;
by the University of Turin under Contract No. BARMRILO-
17; and partly (T.W.D.) by the U.S. Department of
Energy under cooperative agreement DE-FC02-94ER40818.
G.D.M. acknowledges support from a Junta de Andalucia fellowship
(FQM7632, Proyectos de Excelencia 2011). M.B.B.
acknowledges support from the “Emilie du Châtelet” programme
of the P2IO LabEx (ANR-10-LABX-0038)
New 1-aryl-3-substituted propanol derivatives as antimalarial agents
This paper describes the synthesis and in vitro antimalarial activity against a P.
falciparum 3D7 strain of some new 1-aryl-3-substituted propanol derivatives. Twelve of
the tested compounds showed an IC50 lower than 1 μM. These compounds were also tested
for cytotoxicity in murine J774 macrophages. The most active compounds were evaluated
for in vivo activity against P. berghei in a 4-day suppressive test. Compound 12 inhibited
more than 50% of parasite growth at a dose of 50 mg/kg/day. In addition, an FBIT test was
performed to measure the ability to inhibit ferriprotoporphyrin biocrystallization. This data
indicates that 1-aryl-3-substituted propanol derivatives hold promise as a new therapeutic
option for the treatment of malaria
Reflexiones universitarias. San Pedro Valencia: renovación urbana, saneamiento ambiental y emprendimientos turísticos. Otoño 2015
Los trabajos que aquí se presentan se elaboraron por las y los estudiantes como parte de las actividades del Proyecto de Aplicación Profesional (PAP) “San Pedro Valencia: renovación urbana, saneamiento ambiental y emprendimientos turísticos”, durante el periodo de Otoño de 2015. A lo largo del periodo los autores compartieron sus reflexiones en torno a su percepción sobre el contexto en el que actúa el PAP; sobre las alternativas posibles a la problemática detectada y lo que significa pensar una alternativa; sobre los sujetos con los que se ha interactuado a lo largo de la experiencia de trabajo y sobre el papel del profesionista y del ciudadano en un mundo como el que nos tocó vivir. La obra está compuesta por reflexiones personales de las y los estudiantes que, explorando estas temáticas, comparten sus aprendizajes y observaciones de forma vívida.ITESO, A.C
Genomic characterization of individuals presenting extreme phenotypes of high and low risk to develop tobacco-induced lung cancer
Single nucleotide polymorphisms (SNPs) may modulate individual susceptibility to carcinogens. We designed a genome-wide association study to characterize individuals presenting extreme phenotypes of high and low risk to develop tobacco-induced non-small cell lung cancer (NSCLC), and we validated our results. We hypothesized that this strategy would enrich the frequencies of the alleles that contribute to the observed traits. We genotyped 2.37 million SNPs in 95 extreme phenotype individuals, that is: heavy smokers that either developed NSCLC at an early age (extreme cases); or did not present NSCLC at an advanced age (extreme controls), selected from a discovery set (n=3631). We validated significant SNPs in 133 additional subjects with extreme phenotypes selected from databases including >39,000 individuals. Two SNPs were validated: rs12660420 (p(combined)=5.66x10(-5); ORcombined=2.80), mapping to a noncoding transcript exon of PDE10A; and rs6835978 (p(combined)=1.02x10(-4); ORcombined=2.57), an intronic variant in ATP10D. We assessed the relevance of both proteins in early-stage NSCLC. PDE10A and ATP10D mRNA expressions correlated with survival in 821 stage I-II NSCLC patients (p=0.01 and p<0.0001). PDE10A protein expression correlated with survival in 149 patients with stage I-II NSCLC (p=0.002). In conclusion, we validated two variants associated with extreme phenotypes of high and low risk of developing tobacco-induced NSCLC. Our findings may allow to identify individuals presenting high and low risk to develop tobacco-induced NSCLC and to characterize molecular mechanisms of carcinogenesis and resistance to develop NSCLC
Development Refractoriness of MLL-Rearranged Human B Cell Acute Leukemias to Reprogramming into Pluripotency
Induced pluripotent stem cells (iPSCs) are a powerful tool for disease modeling. They are routinely generated from healthy donors and patients from multiple cell types at different developmental stages. However, reprogramming leukemias is an extremely inefficient process. Few studies generated iPSCs from primary chronic myeloid leukemias, but iPSC generation from acute myeloid or lymphoid leukemias (ALL) has not been achieved. We attempted to generate iPSCs from different subtypes of B-ALL to address the developmental impact of leukemic fusion genes. OKSM(L)-expressing mono/polycistronic-, retroviral/lentiviral/episomal-, and Sendai virus vector-based reprogramming strategies failed to render iPSCs in vitro and in vivo. Addition of transcriptomic-epigenetic reprogramming ‘‘boosters’’ also failed to generate iPSCs from B cell blasts and B-ALL lines, and when iPSCs emerged they lacked leukemic fusion genes, demonstrating non-leukemic myeloid origin. Conversely, MLL-AF4-overexpressing hematopoietic stem cells/B progenitors were successfully reprogrammed, indicating that B cell origin and leukemic fusion gene were not reprogramming barriers. Global transcriptome/DNA methylome profiling suggested a developmental/differentiation refractoriness of MLL-rearranged B-ALL to reprogramming into pluripotency
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