5,515 research outputs found
A mid-IR study of Hickson Compact Groups II. Multi-wavelength analysis of the complete GALEX-Spitzer Sample
We present a comprehensive study on the impact of the environment of compact
galaxy groups on the evolution of their members using a multi-wavelength
analysis, from the UV to the infrared, for a sample of 32 Hickson compact
groups (HCGs) containing 135 galaxies. Fitting the SEDs of all galaxies with
the state-of-the-art model of da Cunha (2008) we can accurately calculate their
mass, SFR, and extinction, as well as estimate their infrared luminosity and
dust content. We compare our findings with samples of field galaxies,
early-stage interacting pairs, and cluster galaxies with similar data. We find
that classifying the groups as dynamically "old" or "young", depending on
whether or not at least one quarter of their members are early-type systems, is
physical and consistent with past classifications of HCGs based on their atomic
gas content. [...ABRIDGED...] We also examine their SF properties, UV-optical
and mid-IR colors, and we conclude that all the evidence point to an
evolutionary scenario in which the effects of the group environment and the
properties of the galaxy members are not instantaneous. Early on, the influence
of close companions to group galaxies is similar to the one of galaxy pairs in
the field. However, as the time progresses, the effects of tidal torques and
minor merging, shape the morphology and star formation history of the group
galaxies, leading to an increase of the fraction of early-type members and a
rapid built up of the stellar mass in the remaining late-type galaxies.Comment: Accepted for publication in A&A. Figure resolution degraded for arXiv
limits, full resolution paper available at
http://www.physics.uoc.gr/~bitsakis/paperII_bitsakis.pd
Spin-polarized transport in ferromagnetic multilayered semiconductor nanostructures
The occurrence of inhomogeneous spin-density distribution in multilayered
ferromagnetic diluted magnetic semiconductor nanostructures leads to strong
dependence of the spin-polarized transport properties on these systems. The
spin-dependent mobility, conductivity and resistivity in
(Ga,Mn)As/GaAs,(Ga,Mn)N/GaN, and (Si,Mn)/Si multilayers are calculated as a
function of temperature, scaled by the average magnetization of the diluted
magnetic semiconductor layers. An increase of the resistivity near the
transition temperature is obtained. We observed that the spin-polarized
transport properties changes strongly among the three materials.Comment: 3 pages, 4 figure
Nitrogênio e herbicidas no feijoeiro irrigado cultivado sobre palhadas de Brachiaria decumbens.
Este trabalho teve por objetivo avaliar o efeito de palhadas de Brachiaria decumbens na resposta do feijoeiro à aplicação de doses de N em cobertura, com e sem aplicação de herbicidas para o manejo químico de plantas daninhas em pós-emergência.CONAFE
Electron transfer driven decomposition of adenine and selected analogs as probed by experimental and theoretical methods
We report on a combined experimental and theoretical study of electron transfer induced decomposition of adenine and a selection of analogue molecules in collisions with potassium atoms (K). Time-of-flight negative ion mass spectra have been obtained in a wide collision energy range (6–68 eV in the centre-of-mass frame), providing a comprehensive investigation of the fragmentation patterns of purine, adenine, 9-methyl adenine, 6-dimethyl adenine and 2-D adenine. Following our recent communication about selective hydrogen loss from the transient negative ions (TNI) produced in these collisions [T. Dunha et al. J. Chem. Phys. 148, 021101 (2018)], this work focuses on the production of smaller fragment anions. In the low-energy part of the present range, several dissociation channels that are accessible in free electron attachment experiments are absent from the present mass spectra, notably NH2 loss from adenine and 9-methyl adenine. This can be understood in terms of a relatively long transit time of the K+ cation in the vicinity of the TNI tending to enhance the likelihood of intramolecular electron transfer. In this case, the excess energy can be redistributed through the available degrees of freedom inhibiting fragmentation pathways. Ab initio theoretical calculations were performed for 9-methyl adenine (9-mAd) and adenine (Ad) in the presence of a potassium atom and provided a strong basis for the assignment the lowest unoccupied molecular orbitals accessed in the collision process
Zoneamento de riscos climáticos para a cultura de milho no estado do Rio Grande do Sul: períodos favoráveis de semeadura por município, safra 2004-2005.
bitstream/CNPT-2010/40294/1/p-bp21.pd
Uso do dendrograma de manejo de densidade: uma aplicação prática com Hovenia dulcis Thunberg.
O objetivo principal deste trabalho é fazer uma aplicação prática dos dendrogramas de manejo de densidade em uma população de Hovenía dulcís localizada na região central do estado do Rio Grande do Sul. Para tanto, foram utilizados dados de um povoamento de Hovenia dutcis de aproximadamente 1,3 hectares com 25 anos de idade, localizado em área da Fundação de Pesquisa Agropecuária (FEPAGRO). O dendrograma de densidade utilizado para a simulação das intervenções foi elaborado por Selle (2009), para o local e espécie. Estabeleceu-se que a melhor forma de conduzir o povoamento é com a aplicação de duas intervenções silviculturais, sendo uma aplicada imediatamente e outra, quando o diâmetro da árvore de área basal média atingir 27 em. No primeiro desbaste devem ser retiradas 36,6% e no segundo 33,3% das árvores, correspondendo a 33,6 e 45,6% da área basal, respectivamente
Épocas de aplicação e fontes nitrogenadas no desenvolvimento do feijoeiro.
O objetivo deste trabalho foi avaliar o efeito da época de aplicação e de fontes nitrogenadas em cobertura no crescimento do feijoeiro cultivado em sistema plantio direto.CONAFE
Resíduos comuns na Embrapa Clima Temperado: coleta seletiva.
bitstream/item/165307/1/Documentos-422.pd
Quantificação indireta do crescimento celular de aspergillus niger em meio contendo bagaço de cana-de-açúcar visando fermentação em biorreator do tipo airlift.
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