567 research outputs found
Galaxy Cosmological Mass Function
We study the galaxy cosmological mass function (GCMF) in a semi-empirical
relativistic approach using observational data provided by galaxy redshift
surveys. Starting from the theory of Ribeiro & Stoeger (2003,
arXiv:astro-ph/0304094) between the mass-to-light ratio, the selection function
obtained from the luminosity function (LF) data and the luminosity density, the
average luminosity and the average galactic mass are
computed in terms of the redshift. is also alternatively
estimated by a method that uses the galaxy stellar mass function (GSMF).
Comparison of these two forms of deriving the average galactic mass allows us
to infer a possible bias introduced by the selection criteria of the survey. We
used the FORS Deep Field galaxy survey sample of 5558 galaxies in the redshift
range and its LF Schechter parameters in the B-band, as well as
this sample's stellar mass-to-light ratio and its GSMF data. Assuming
as the local value of
the average galactic mass, the LF approach results in and .
However, using the GSMF results produces . We chose the latter result as it is less biased. We then obtained
the theoretical quantities of interest, such as the differential number counts,
to calculate the GCMF, which can be fitted by a Schechter function. The derived
GCMF follows theoretical predictions in which the less massive objects form
first, being followed later by more massive ones. In the range
the GCMF has a strong variation that can be interpreted as a higher rate of
galaxy mergers or as a strong evolution in the star formation history of these
galaxies.Comment: In memory of William R. Stoeger (1943-2014). LaTeX, 8 pages, 7
figures. Minor changes to match version sent to publisher. To appear in
"Astronomy and Astrophysics
Composição química e atividade inibidora de acetilcolinesterase de óleos voláteis de Myrceugenia myrcioides(Cambess.) O. Berg and Eugenia riedeliana O. Berg, Myrtaceae
The chemical composition of volatile oils from two Myrtaceae species, Myrceugenia myrcioidesand Eugenia riedeliana, both native from the Brazilian Atlantic Rain Forest, was analyzed by GC-MS. Acetylcholinesterase inhibitory activity was colorimetrically evaluated for these oils. For M. myrcioides, monoterpene hydrocarbons represented the major class in the volatile oil, with α-pinene as the most abundant component and a weak inhibitory activity was observed, whilst for E. riedeliana sesquiterpenes were found in higher amounts, being valerianol the major compound, and this oil presented a strong acetylcholinesterase inhibition.A composição química dos óleos voláteis de duas espécies de Myrtaceae, Myrceugenia myrcioidese Eugenia riedeliana, ambas nativas da Mata Atlântica, foi analisada por CG-EM. A atividade inibidora de acetilcolinesterase foi determinada colorimetricamente para estes óleos. Em M. myrcioides, hidrocarbonetos monoterpênicos representaram a classe majoritária de compostos presentes no óleo volátil, sendo α-pineno o componente mais abundante e a atividade inibidora de acetilcolinesterase foi baixa, enquanto para E. riedelianaos sesquiterpenos foram observados em maiores concentrações, sendo o valerianol o componente majoritário, e este óleo apresentou uma forte atividade inibidora da enzima.BIOTA/FAPESPCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES
A large Venous-Arterial PCO2 Is Associated with Poor Outcomes in Surgical Patients
Background. This study evaluated whether large venous-arterial CO2 gap (PCO2 gap) preoperatively is associated to poor outcome. Method. Prospective study which included adult high-risk surgical patients. The patients were pooled into two groups: wide [P(v-a)CO2] versus narrow [P(v-a)CO2]. In order to determine the best value to discriminate hospital mortality, it was applied a ROC (receiver operating characteristic) curve for the [P(v-a)CO2] values collected preoperatively, and the most accurate value was chosen as cut-off to define the groups. Results. The study included 66 patients. The [P(v-a)CO2] value preoperatively that best discriminated hospital mortality was 5.0 mmHg, area = 0.73. Preoperative patients with [P(v-a)CO2] more than 5.0 mmHg presented a higher hospital mortality (36.4% versus 4.5% P = 0.004), higher prevalence of circulatory shock (56.8% versus 22.7% P = 0.01) and acute renal failure postoperatively (27.3% versus 4.5% P = 0.02), and longer hospital length of stays 20.0 (14.0–30.0) versus 13.5 (9.0–25.0) days P = 0.01. Conclusions. The PCO2 gap values more than 5.0 mmHg preoperatively were associated with worse postoperatively outcome
Systematic analysis of jellyfish galaxy candidates in Fornax, Antlia, and Hydra from the S-PLUS survey: A self-supervised visual identification aid
© 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/We study 51 jellyfish galaxy candidates in the Fornax, Antlia, and Hydra clusters. These candidates are identified using the JClass scheme based on the visual classification of wide-field, twelve-band optical images obtained from the Southern Photometric Local Universe Survey. A comprehensive astrophysical analysis of the jellyfish (JClass > 0), non-jellyfish (JClass = 0), and independently organized control samples is undertaken. We develop a semi-automated pipeline using self-supervised learning and similarity search to detect jellyfish galaxies. The proposed framework is designed to assist visual classifiers by providing more reliable JClasses for galaxies. We find that jellyfish candidates exhibit a lower Gini coefficient, higher entropy, and a lower 2D Sérsic index as the jellyfish features in these galaxies become more pronounced. Jellyfish candidates show elevated star formation rates (including contributions from the main body and tails) by 1.75 dex, suggesting a significant increase in the SFR caused by the ram-pressure stripping phenomenon. Galaxies in the Antlia and Fornax clusters preferentially fall towards the cluster's centre, whereas only a mild preference is observed for Hydra galaxies. Our self-supervised pipeline, applied in visually challenging cases, offers two main advantages: it reduces human visual biases and scales effectively for large data sets. This versatile framework promises substantial enhancements in morphology studies for future galaxy image surveys.Peer reviewe
ASPHER Statement: Facing the Fourth Winter of the COVID-19 Pandemic
From Frontiers via Jisc Publications RouterHistory: collection 2022, received 2022-09-14, accepted 2022-09-20, epub 2022-10-03Peer reviewed: TruePublication status: Publishe
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