574 research outputs found
Where does the gas fueling star formation in BCGs originate?
We investigate the relationship between X-ray cooling and star formation in
brightest cluster galaxies (BCGs). We present an X-ray spectral analysis of the
inner regions, 10-40 kpc, of six nearby cool core clusters (z<0.35) observed
with Chandra ACIS. This sample is selected on the basis of the high star
formation rate (SFR) observed in the BCGs. We restrict our search for cooling
gas to regions that are roughly cospatial with the starburst. We fit single-
and multi-temperature mkcflow models to constrain the amount of isobarically
cooling intracluster medium (ICM). We find that in all clusters, below a
threshold temperature ranging between 0.9 and 3 keV, only upper limits can be
obtained. In four out of six objects, the upper limits are significantly below
the SFR and in two, namely A1835 and A1068, they are less than a tenth of the
SFR. Our results suggests that a number of mechanisms conspire to hide the
cooling signature in our spectra. In a few systems the lack of a cooling
signature may be attributed to a relatively long delay time between the X-ray
cooling and the star burst. However, for A1835 and A1068, where the X-ray
cooling time is shorter than the timescale of the starburst, a possible
explanation is that the region where gas cools out of the X-ray phase extends
to very large radii, likely beyond the core of these systems.Comment: to appear in A&
A textbook example of ram-pressure stripping in the Hydra A/A780 cluster
In the current epoch, one of the main mechanisms driving the growth of galaxy clusters is the continuous accretion of group-scale halos. In this process, the ram pressure applied by the hot intracluster medium on the gas content of the infalling group is responsible for stripping the gas from its dark-matter halo, which gradually leads to the virialization of the infalling gas in the potential well of the main cluster. Using deep wide-field observations of the poor cluster Hydra A/A780 with XMM-Newton and Suzaku, we report the discovery of an infalling galaxy group 1.1 Mpc south of the cluster core. The presence of a substructure is confirmed by a dynamical study of the galaxies in this region. A wake of stripped gas is trailing behind the group over a projected scale of 760 kpc. The temperature of the gas along the wake is constant at kT ~ 1.3 keV, which is about a factor of two less than the temperature of the surrounding plasma. We observe a cold front pointing westwards compared to the peak of the group, which indicates that the group is currently not moving in the direction of the main cluster, but is moving along an almost circular orbit. The overall morphology of the group bears remarkable similarities with high-resolution numerical simulations of such structures, which greatly strengthens our understanding of the ram-pressure stripping process
Expressão gênica diferencial em fruto de Coffea arabica L. em diferentes estádios de desenvolvimento e maturação.
O cafeeiro arábica apresenta além da florada principal outras sucessivas floradas, o que resulta em uma maturação desuniforme dos frutos. A diferença de maturação entre e dentro de floradas, traz inconvenientes à colheita, tornando-a onerosa e prejudicando a qualidade final da bebida. Durante o processo de desenvolvimento e maturação dos frutos de café vários genes são ativados. O objetivo desse trabalho é então avaliar como os genes ?galactosidase e ?mannanase relacionados ao desenvolvimento e aturação dos frutos se comportam nas diferentes fases de maturação dos frutos. O datamining foi realizado utilizando-se seqüências dos genes ?galactosidase e ?mannanase de Coffea presentes no GenBank. Oligos gene específicos foram desenhados a partir das seqüências identificadas no Banco do Genoma Café. Análises do padrão de expressão demonstraram que transcritos correspondentes à galactosidase são observados a partir da fase de frutos em expansão e se mantém presentes até o estágio de fruto cereja. Já a expressão da ?mannanase é observada ao longo de todo o desenvolvimento do fruto, com um maior acúmulo na fase de frutos verdes. Estes resultados, apesar de representarem uma caracterização inicial do padrão de expressão em frutos, são essenciais para estabelecimento de parâmetros agronômicos e da metodologia para análise molecular em frutos de cultivares comerciais do IA
Caracterização de genes expressos durante o crescimento e maturação de frutos de café.
O objetivo do estudo foi caracterizar funcionalmente genes-chave expressos durante o crescimento e a maturação de frutos de cultivares de Coffea arabica L, pois a planta apresenta várias floradas, fato que resulta na maturação desigual de frutos, inclusive na mesma florada. Para o estudo foram utilizadas frutos em desenvolvimento das cultivares: Mundo Novo IAC 388-17, Catuaí Vermelho IAC 144, Icatu Vermelho IAC 4045, Obatã IAC 1669-20 e Icatu Precoce IAC 3282. Os genes escolhidos para análise foram: o fator de transcrição Leafy Cotyledon (LEC1) e as enzimas álcool acyl transferase e ácido 1-carboxílico 1-aminociclopropano (ACC) oxidase, os quais estão relacionados com os processos de desenvolvimento do embrião, composição química da semente e maturação do fruto, respectivamente. A expressão dos genes foi avaliada através da metodologia de RT-PCR, utilizando RNA total extraído dos frutos. Os resultados apresentados evidenciam que o padrão de expressão dos genes ACC oxidase, LEC1 e álcool acyl transferase são compatíveis com o esperado em frutos climatéricos e, as variações na expressão dos genes observada entre as cultivares sugerem que a composição química e a maturação dos frutos podem diferir ao longo do desenvolvimento dos frutos
Produção de anticorpos monoclonais anti-cisticercos de Taenia crassiceps com reatividade cruzada com antígenos de Taenia solium
We describe the production of the potential monoclonal antibodies (MoAbs) using BALB/c mice immunized with vesicular fluid (VF)-Tcra (T. crassiceps) antigen. Immune sera presented anti-VF-Tcra (É descrita a produção de potenciais anticorpos monoclonais (MoAbs) usando camundongos BALB/c imunizados com antígenos de líquido vesicular de T. crassiceps (VF-Tcra). O soro imune apresentou anticorpos IgM e IgG anti-VF-Tcra para os peptídeo
Expressão gênica em grãos de café submetidos a diferentes tratamentos pós-colheita-uma análise preliminar.
O conhecimento sobre como os tipos de processamento pós-colheita interferem na qualidade final de bebida é essencial para que cafés com qualidades especiais possam ser desenvolvidos. Dentre as características que podem ser diretamente influenciadas pelo processamento, a composição química do grão é a de maior interesse. Fatores como a regulação da expressão de genes e a atividade de enzimas específicas são determinantes para esta composição. Neste contexto, o objetivo deste estudo preliminar foi avaliar como os processamentos por via seca e úmida afetam o padrão de expressão dos genes isocitrato liase (ICL), ?-mananase (MAN) e ?-galactosidase (GAL). Frutos cereja foram submetidos a condições de secagem natural, despolpamento e desmucilamento. A expressão dos genes foi quantificada pela metodologia de RT-PCR em tempo real. A análise comparativa da expressão dos 3 genes indicou que no processamento via seca a expressão de ICL e MAN nas sementes foi maior do que em sementes de frutos processados por via úmida. Para o gene GAL, não foram observadas diferenças expressivas no perfil de expressão em sementes dos frutos submetidos aos diferentes tratamentos. Esses resultados diferiram dos obtidos em outros estudos já descritos na literatura, em que, apesar de ter sido avaliada a expressão de genes, foram utilizadas etapas de processamento distintas das utilizadas neste trabalho. Esses resultados revelaram, portanto, que há necessidade de se padronizarem os processamentos experimentais em pesquisas visando avaliar efeitos dos tratamentos pós-colheita sobre a qualidade do café
Influence of the Ion Coordination Number on Cation Exchange Reactions with Copper Telluride Nanocrystals
Cu2-xTe nanocubes were used as starting seeds to access metal telluride
nanocrystals by cation exchanges at room temperature. The coordination number
of the entering cations was found to play an important role in dictating the
reaction pathways. The exchanges with tetrahedrally coordinated cations (i.e.
with coordination number 4), such as Cd2+ or Hg2+, yielded monocrystalline CdTe
or HgTe nanocrystals with Cu2-xTe/CdTe or Cu2-xTe/HgTe Janus-like
heterostructures as intermediates. The formation of Janus-like architectures
was attributed to the high diffusion rate of the relatively small tetrahedrally
coordinated cations, which could rapidly diffuse in the Cu2-xTe NCs and
nucleate the CdTe (or HgTe) phase in a preferred region of the host structure.
Also, with both Cd2+ and Hg2+ ions the exchange led to wurtzite CdTe and HgTe
phases rather than the more stable zinc-blende ones, indicating that the anion
framework of the starting Cu2- xTe particles could be more easily deformed to
match the anion framework of the metastable wurtzite structures. As hexagonal
HgTe had never been reported to date, this represents another case of
metastable new phases that can only be accessed by cation exchange. On the
other hand, the exchanges involving octahedrally coordinated ions (i.e. with
coordination number 6), such as Pb2+ or Sn2+, yielded rock-salt polycrystalline
PbTe or SnTe nanocrystals with Cu2-xTe@PbTe or Cu2-xTe@SnTe core@shell
architectures at the early stages of the exchange process. In this case, the
octahedrally coordinated ions are probably too large to diffuse easily through
the Cu2-xTe structure: their limited diffusion rate restricts their initial
reaction to the surface of the nanocrystals, where cation exchange is initiated
unselectively, leading to core@shell architectures.Comment: 11 pages, 7 figures in J. Am. Chem. Soc, 13 May 201
The evolving cluster cores: Putting together the pieces of the puzzle
In this work we address the issue of whether the division of clusters in cool
cores (CCs) and non-cool cores (NCCs) is due to a primordial difference or to
how clusters evolve across cosmic time. Our first goal is to establish if
spectra from the central regions of a subclass of NCCs known as cool core
remnants (CCRs) are consistent with having a small but significant amount of
short cooling time gas, thereby allowing a transformation to CC systems on a
timescale of a giga year. Our second goal is to determine if low ionization Fe
lines emitted from this residual cool gas will be detectable by the
calorimeters that will fly on board XRISM and ATHENA. We performed a spectral
analysis of CCR systems with a multi temperature model and, assuming the
different components to be in pressure equilibrium with one another, derived
entropy and cooling time distributions for the X-ray emitting gas. We find that
in most of our systems, the spectral model allows for a fraction of low
entropy, short cooling time gas with a mass that is comparable to the one in CC
systems. Moreover, simulations show that future spectrometers on board XRISM
and ATHENA will have the power to directly resolve emission lines from the low
temperature gas, thereby providing incontrovertible evidence for its presence.
Within the scenario that we have explored, the constant fraction of CCs
measured across cosmic time emerges from a dynamical equilibrium where CCs
transformed in NCCs through mergers are balanced by NCCs that revert to CCs.
Furthermore, CCs and NCCs should not be viewed as distinct sub classes, but as
``states" between which clusters can move.Comment: To appear in Astronomy & Astrophysic
Metodologia para avaliação do comportamento fenológico de cultivares de Coffea arabica.
O estudo foi realizado com o objetivo de observar, no momento da colheita, o comportamento fenológico de cultivares de Coffea arabica, para identificar diferenças de uniformidade na maturação e definir ciclos: precoces, médios e tardios em duas safras consecutivas, 2004/2005 e 2005/2006. Os dois anos agrícolas foram bastante distintos climaticamente, fazendo com que as cultivares tivessem comportamentos diferentes, inclusive quanto ao número de floradas significativas, o que proporcionou aumento de desuniformidade na colheita. Com os resultados obtidos, observou que o desenvolvimento fenológico é uma característica altamente influenciada pelo ambiente e, para avaliação de ciclos e uniformidade as cultivares, devem ser avaliadas por mais de duas safras consecutivas
Etanercept Improves Lipid Profile and Oxidative Stress Measures in Patients with Juvenile Idiopathic Arthritis
Objective.To investigate the effect of 1-year treatment with the anti-tumor necrosis factor-α (TNF-α) drug etanercept on lipid profile and oxidative stress in children and adolescents with juvenile idiopathic arthritis (JIA).Methods.Thirty children with JIA (22 females; mean age 12.3 ± SD 5.7 yrs), all eligible for anti-TNF-α treatment, were assessed at baseline and after 6- and 12-month treatment with etanercept. Disease activity was determined using the Juvenile Arthritis Disease Activity Score (JADAS). Blood samples were drawn to measure the acute-phase reactants C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR), lipids, and the proinflammatory cytokines TNF-α, interleukin-1β (IL-1β), IL-6 and interferon-γ. To measure the oxidative stress marker 8-iso-prostaglandin F2α, 24-h urine samples were collected.Results.Inflammatory indicators (CRP and ESR) and JADAS scores improved significantly after 1 year of etanercept treatment (all p < 0.001). Proinflammatory cytokines showed significant reduction during the study period (all p < 0.001). Similar reductions were detected in total cholesterol (p < 0.001), low-density lipoprotein cholesterol (p = 0.04), and triglycerides (p < 0.001), whereas no significant change was found in high-density lipoprotein cholesterol. No side effects were observed during the treatment period.Conclusion.This study shows for the first time that anti-TNF-α therapy for JIA is associated not only with a beneficial effect on clinical disease activity and inflammatory indexes, but also with improved lipid profile and oxidative stress. These findings suggest that TNF-α blockers might reduce atherosclerotic risk in children with JIA
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