1,101 research outputs found
El ensayo de micronúcleos como medida de inestabilidad genética inducida por agentes genotóxicos
Human genetic integrity is compromised by the intense industrial activity, which emphasizes the importance to determine an "acceptable" genetic damage level and to carry out routine genotoxicity assays in the populations at risk. Micronuclei are cytoplasmatic bodies of nuclear origin which correspond to genetic material that is not correctly incorporated in the daughter cells in the cellular division; they reflect the existence of chromosomal aberrations and are originated by chromosomal breaks, replication errors followed by cellular division of the DNA and/or exposure to genotoxic agents. There are several factors able to modify the number of micronuclei present in a given cell, among them are age, gender, vitamins, medical treatments, daily exposure to genotoxic agents, etc. The cytogenetic assay for the detection of micronuclei (CBMN: cytokinesis-block micronucleus) is based on the use of a chemical agent, cytochalasin-B, which is able to block cytocinesis but allowing the nuclear division, therefore yielding binucleated and monodivided cells. The micronuclei scoring is performed on 1000 binucleated cells and the starting sample may vary, although most studies are performed on peripheral blood lymphocytes. The micronuclei assay is considered a practical, universally validated and technically feasible protocol which is useful to evaluate the genetic instability induced by genotoxic agent
Refining the associations of the Fermi Large Area Telescope Source Catalogs
The Fermi-Large Area Telescope (LAT) First Source Catalog (1FGL) was released
in February 2010 and the Fermi-LAT 2-Year Source Catalog (2FGL) appeared in
April 2012, based on data from 24 months of operation. Since their releases,
many follow up observations of unidentified gamma-ray sources (UGSs) were
performed and new procedures to associate gamma-ray sources with potential
counterparts at other wavelengths were developed. Here we review and
characterize all the associations as published in the 1FGL and 2FGL catalog on
the basis of multifrequency archival observations. In particular we located 177
spectra for the low-energy counterparts that were not listed in the previous
Fermi catalogs, and in addition we present new spectroscopic observations of 8
gamma-ray blazar candidates. Based on our investigations, we introduce a new
counterpart category of "candidate associations" and propose a refined
classification for the candidate low-energy counterparts of the Fermi sources.
We compare the 1FGL-assigned counterparts with those listed in the 2FGL to
determine which unassociated sources became associated in later releases of the
Fermi catalogs. We also search for potential counterparts to all the remaining
unassociated Fermi sources. Finally, we prepare a refined and merged list of
all the associations of the 1FGL plus 2FGL catalogs that includes 2219 unique
Fermi objects. This is the most comprehensive and systematic study of all the
associations collected for the gamma-ray sources available to date. We conclude
that 80% of the Fermi sources have at least one known plausible gamma-ray
emitter within their positional uncertainty regions.Comment: 26 pages, 24 figures, 7 tables, ApJS accepted for publication
(pre-proof version uploaded
Ajitts: adaptive just-in-time transaction scheduling
Lecture Notes in Computer Science 7891, 2013Distributed transaction processing has benefited greatly from optimistic concurrency control protocols thus avoiding costly fine-grained synchronization. However, the performance of these protocols degrades significantly when the workload increases, namely, by leading to a substantial amount of aborted transactions due to concurrency conflicts. Our approach stems from the observation that when the abort rate increases with the load as already executed transactions queue for longer periods of time waiting for their turn to be certified and committed. We thus propose an adaptive algorithm for judiciously scheduling transactions to minimize the time during which these are vulnerable to being aborted by concurrent transactions, thereby reducing the overall abort rate. We do so by throttling transaction execution using an adaptive mechanism based on the locally known state of globally executing transactions, that includes out-of-order execution.
Our evaluation using traces from the industry standard TPC-E workload shows that the amount of aborted transactions can be kept bounded as system load increases, while at the same time fully utilizing system resources and thus scaling transaction processing throughput.(undefined
Pasado, presente y futuro del búfalo en Argentina
El búfalo comenzó a ser introducido al país a comienzo el siglo XX, mediante la importación razas Mediterránea, Murrah y Jafarabadi. En la actualidad la población bubalina alcanzó las de 87.711 cabezas y se encuentran distribuidas en 20 de las 23 provincias que componen el territorio nacional. El 80 % de la población de búfalos se encuentran en el nordeste argentino. Siendo las provincias de Formosa y Corrientes las que cuentan con la mayores poblaciones bubalinas. Existen en el país 8 millones de hectáreas aptas para soportar una carga de 4 millones de búfalos.The buffalo began to be introduced to the country in the early twentieth century, by importing Mediterranean, Murrah and Jafarabadi breeds. Today buffalo population reached 87.711 heads, which are distributed in 20 out of the 23 provinces that conforms the country. The 80% of the population of buffaloes is found in northeastern region, being the provinces of Formosa and Corrientes those with the largest buffalo population. The country has 8 million hectares suitable to withstand a load of 4 million buffaloes.Fil: Crudeli, G. A.. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias; ArgentinaFil: Patiño, E. M.. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias; ArgentinaFil: Maldonado Vargas, P.. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias; ArgentinaFil: Konrad, José Luis. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Nordeste. Facultad de Cs.veterinarias; Argentin
Flare-like Variability of the Mg~II 2798 \AA\ Emission Line and UV Fe~II band in the Blazar CTA~102
We report on the detection of a statistically significant flare-like event in
the Mg~II~ 2798~\AA\ emission line and the UV~Fe~II band of CTA~102
during the outburst of autumn 2017. The ratio between the maximum and minimum
of 3000~\AA\ continuum flux for the observation period ()
is 17915. Respectively, the max/min ratios 8.110.5 and 34.045.5
confirmed the variability of the Mg~II emission line and of the Fe~II band. The
highest levels of emission lines fluxes recorded coincide with a superluminal
jet component traversing through a stationary component located at 0.1
mas from the 43 GHz core. Additionally, comparing the Mg~II line profile in the
minimum of activity against the one in the maximum, we found that the latter is
broader and blue-shifted. As a result of these findings, we can conclude that
the non-thermal continuum emission produced by material in the jet moving at
relativistic speeds is related to the broad emission line fluctuations. In
consequence, these fluctuations are also linked to the presence of broad-line
region (BLR) clouds located at 25 pc from the central engine, outside
from the inner parsec, where the canonical BLR is located. Our results suggest
that during strong activity in CTA~102, the source of non-thermal emission and
broad-line clouds outside the inner parsec introduces uncertainties in the
estimates of black hole (BH) mass. Therefore, it is important to estimate the
BH mass, using single-epoch or reverberation mapping techniques, only with
spectra where the continuum luminosity is dominated by the accretion disk.Comment: 15 pages, 6 figures, 2 tables, accepted for publication in Ap
CONTRIBUTIONS TO RICKETTSIOSES RESEARCH IN COLOMBIA (1917-1943), LUIS B. PATIÑO CAMARGO
Optical archival spectra of blazar candidates of uncertain type in the 3 Fermi Large Area Telescope Catalog
Despite the fact that blazars constitute the rarest class among active
galactic nuclei (AGNs) they are the largest known population of associated
-ray sources. Many of the -ray objects listed in the
Fermi-Large Area Telescope Third Source catalog (3FGL) are classified as blazar
candidates of uncertain type (BCUs), either because they show multifrequency
behaviour similar to blazars but lacking optical spectra in the literature, or
because the quality of such spectra is too low to confirm their nature. Here we
select, out of 585 BCUs in the 3FGL, 42 BCUs which we identify as probable
blazars by their WISE infrared colors and which also have optical spectra that
are available in the Sloan Digital Sky Survey (SDSS) and/or Six-Degree Field
Galaxy Survey Database (6dFGS). We confirm the blazar nature of all of the
sources. We furthermore conclude that 28 of them are BL Lacs, 8 are radio-loud
quasars with flat radio spectrum and 6 are BL Lac whose emission is dominated
by their host galaxy
Early Science with the Large Millimeter Telescope: an energy-driven wind revealed by massive molecular and fast X-ray outflows in the Seyfert Galaxy IRAS 17020+4544
We report on the coexistence of powerful gas outflows observed in millimeter
and X-ray data of the Radio-Loud Narrow Line Seyfert 1 Galaxy IRAS 17020+4544.
Thanks to the large collecting power of the Large Millimeter Telescope, a
prominent line arising from the 12CO(1-0) transition was revealed in recent
observations of this source. The complex profile is composed by a narrow
double-peak line and a broad wing. While the double-peak structure may be
arising in a disk of molecular material, the broad wing is interpreted as the
signature of a massive outflow of molecular gas with an approximate bulk
velocity of -660 km/s. This molecular wind is likely associated to a
multi-component X-ray Ultra-Fast Outflow with velocities reaching up to ~0.1c
and column densities in the range 10^{21-23.9} cm^-2 that was reported in the
source prior to the LMT observations. The momentum load estimated in the two
gas phases indicates that within the observational uncertainties the outflow is
consistent with being propagating through the galaxy and sweeping up the gas
while conserving its energy. This scenario, which has been often postulated as
a viable mechanism of how AGN feedback takes place, has so far been observed
only in ULIRGs sources. IRAS 17020+4544 with bolometric and infrared luminosity
respectively of 5X10^{44} erg/s and 1.05X10^{11} L_sun appears to be an example
of AGN feedback in a NLSy1 Galaxy (a low power AGN). New proprietary
multi-wavelength data recently obtained on this source will allow us to
corroborate the proposed hypothesis.Comment: Accepted for publication on ApJ Letters, 9 pages, 4 figure
Methotrexate in Pediatric Osteosarcoma: Response and Toxicity in Relation to Genetic Polymorphisms and Dihydrofolate Reductase and Reduced Folate Carrier 1 Expression
To determine the influence of the genotype and the level of expression of different enzymes involved in folate metabolism on the response to and toxicity of high-dose methotrexate treatment in pediatric osteosarcomas.
STUDY DESIGN: DHFR and Reduced folate carrier 1 (RFC1) semiquantitative expression was analyzed in 34 primary and metastatic osteosarcoma tissues by real-time polymerase chain reaction. The following polymorphisms were also analyzed in peripheral blood from 96 children with osteosarcoma and 110 control subjects: C677T, A1298C (MTHFR), G80A (RFC1), A2756G (MTR), C1420T (SHMT), the 28bp-repeat polymorphism, and 1494del6 of the TYMS gene. Treatment toxicity was scored after each cycle according to criteria from the World Health Organization.
RESULTS: DHFR and RFC1 expression was lower in initial osteosarcoma biopsy specimens than in metastases (P = .024 and P = .041, respectively). RFC1 expression was moderately decreased in samples with poor histologic response to preoperative treatment (P = .053). Patients with osteosarcoma with G3/G4 hematologic toxicity were more frequently TT than CT/CC for C677T/MTHFR (P = .023) and GG for A2756G/MTR (P = .048 and P = .057 for gastrointestinal and hematologic toxicity, respectively).
CONCLUSIONS: The role of C677T/MTHFR and A2756G/MTR on chemotherapy-induced toxicity should be further investigated in pediatric osteosarcomas receiving high-dose methotrexate. Altered expression of DHFR and RFC1 is a feasible mechanism by which osteosarcoma cells become resistant to methotrexate
The Gamma-ray Blazar Quest: new optical spectra, state of art and future perspectives
We recently developed a procedure to recognize gamma-ray blazar candidates
within the positional uncertainty regions of the unidentified/unassociated
gamma-ray sources (UGSs). Such procedure was based on the discovery that Fermi
blazars show peculiar infrared colors. However, to confirm the real nature of
the selected candidates, optical spectroscopic data are necessary. Thus, we
performed an extensive archival search for spectra available in the literature
in parallel with an optical spectroscopic campaign aimed to reveal and confirm
the nature of the selected gamma-ray blazar candidates. Here, we first search
for optical spectra of a selected sample of gamma-ray blazar candidates that
can be potential counterparts of UGSs using the Sloan Digital Sky Survey (SDSS
DR12). This search enables us to update the archival search carried out to
date. We also describe the state-of-art and the future perspectives of our
campaign to discover previously unknown gamma-ray blazars.Comment: 11 pages, 2 figures, 5 tables, pre-proof version, accepted for
publication of Astrophysics and Space Scienc
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