96 research outputs found
An X-ray characterization of the central region of the SNR G332.5-5.6
We present an X-ray analysis of the central region of supernova remnant (SNR)
G332.5-5.6 through an exhaustive analysis of XMM-Netwon observations with
complementary infrared observations. We characterize and discuss the origin of
the observed X-ray morphology, which presents a peculiar plane edge over the
west side of the central region. The morphology and spectral properties of the
X-ray supernova remnant were studied using a single full frame XMM-Newton
observation in the 0.3 to 10.0 keV energy band. Archival infrared WISE
observations at 8, 12 and 24 \mu m were also used to investigate the properties
of the source and its surroundings at different wavelengths. The results show
that the extended X-ray emission is predominantly soft (0.3-1.2 keV) and peaks
around 0.5 keV, which shows that it is an extremely soft SNR. X-ray emission
correlates very well with central regions of bright radio emission. On the west
side the radio/X-ray emission displays a plane-like feature with a terminal
wall where strong infrared emission is detected. Our spatially resolved X-ray
spectral analysis confirms that the emission is dominated by weak atomic
emission lines of N, O, Ne, and Fe, all of them undetected in previous X-ray
studies. These characteristics suggest that the X-ray emission is originated in
an optically thin thermal plasma, whose radiation is well fitted by a
non-equilibrium ionization collisional plasma (VNEI) X-ray emission model. Our
study favors a scenario where G332.5-5.6 is expanding in a medium with an
abrupt density change (the wall), likely a dense infrared emitting region of
dust on the western side of the source.Comment: 7 pages, 5 figures and 2 tables. Accepted for publication in A&
Detailed study of SNR G306.3-0.9 using XMM-Newton and Chandra observations
We used combined data from XMM-Newton and Chandra observatories to study the
X-ray morphology of SNR G306.3-0.9. A spatially-resolved spectral analysis was
used to obtain physical and geometrical parameters of different regions of the
remnant. Spitzer infrared observations were also used to constrain the
progenitor supernova and study the environment in which the SNR evolved. The
X-ray morphology of the remnant displays a non-uniform structure of
semi-circular appearance, with a bright southwest region and very weak or
almost negligible X-ray emission in its northern part. These results indicate
that the remnant is propagating in a non-uniform environment as the shock
fronts are encountering a high-density medium, where enhanced infrared emission
is detected. The X-ray spectral analysis of the selected regions shows distinct
emission-line features of several metal elements, confirming the thermal origin
of the emission. The X-ray spectra are well represented by a combination of two
absorbed thermal plasma models: one in equilibrium ionization with a mean
temperature of ~0.19 keV, and another out of equilibrium ionization at a higher
temperature of ~1.1 or 1.6-1.9 keV. For regions located in the northeast,
central, and southwest part of the SNR, we found elevated abundances of Si, S,
Ar, Ca, and Fe, typical of ejecta material. The outer regions located northwest
and south show values of the abundances above solar but lower than to those
found in the central regions. This suggests that the composition of the
emitting outer parts of the SNR is a combination of ejecta and shocked material
of the interstellar medium. The comparison between the S/Si, Ar/Si, and Ca/Si
abundances ratios (1.75, 1.27, and 2.72 in the central region, respectively),
favor a Type Ia progenitor for this SNR, a result that is also supported by an
independent morphological analysis using X-ray and IR data.Comment: 8 pages, 7 figures. Accepted by Astronomy and Astrophysic
Resposta de Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae) a diferentes densidades de ovos do hospedeiro natural, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae).
Avaliou-se em laboratorio (25oC), 70% UR e fotofase de 12 horas) a resposta de diferentes densidades de Trichogramma atopovirilia Oatman & Platner ao aumento da densidade de ovos do hospedeiro Helicoverpa zea (Boddie). Uma, tres, cinco e 10 femeas do parasitoide, receberam, por um periodo de 24 h, 15, 30, 60, 90, 120 e 150 ovos do hospedeiro. Os resultados indicaram uma interferencia mutua tanto do hospedeiro quanto do parasitoide, em tratamento com tres ou mais femeas confinadas nos tubos, e em baixas densidades de ovos do hospedeiro , resultando mum menor numero de ovos parasitados por femea. Numa densidade de 120 ovos do hospedeiro ou acima (no minimo 12 ovos disponiveis/femea) nao ocorreu inerferencia mutua. Respostas funcionais quadraticas foram verificadas para o numero de ovos parasitados com o aumento de densidade de ovos, para uma densidade de cinco ou mais parasitoides por recipiente
Efeito de genótipos de milho no parasitismo por Trichogramma spp. em ovos de Helicoverpa zea (Boddie).
Avaliou-se o parasitismo de ovos de Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) por Trichogramma spp, em tres genotipos de milho (Zea mays L.); BR 205 (endosperma amarelo normal), BR 451 (endosperma branco, com alta qualidade proteica e BR 400 (endosperma amarelo e doce). Os genotipos foram semeados de duas maneiras; plantio dos tres genotipos ao mesmo tempo (1o ensaio) e plantio escalonado com intervalo de uma semana, para coincidir o florescimento, a saber; BR 205, BR 451 e BR 400. Em ambos os plantios nao houve efeito dos genotipos na infestacao de ovos de H. zea e no parasitismo desses por Trichogramma spp. (media de 8,0 no 1o e de 1,8 ovos/estilo-estigma, no 2o plantio). O parasitismo dos ovos significativamente de acordo com a cultivar, sendo de 62,4% para BR 451, 47,0% para BR 205 e 34,1% para BR 400
Cosmic rays in the surroundings of SNR G35.6-0.4
HESS J1858+020 is a TeV gamma-ray source that was reported not to have any
clear cataloged counterpart at any wavelength. However, it has been recently
proposed that this source is indirectly associated with the radio source,
re-identified as a supernova remnant (SNR), G35.6-0.4. The latter is found to
be middle-aged ( kyr) and to have nearby molecular clouds (MCs). HESS
J1858+020 was proposed to be the result of the interaction of protons
accelerated in the SNR shell with target ions residing in the clouds. The Fermi
Large Area Telescope (LAT) First Source Catalog does not list any source
coincident with the position of HESS J1858+020, but some lie close. Here, we
analyse more than 2 years of data obtained with the Fermi-LAT for the region of
interest, and consider whether it is indeed possible that the closest LAT
source, 1FGL J1857.1+0212c, is related to HESS J1858+020. We conclude it is
not, and we impose upper limits on the GeV emission originating from HESS
J1858+020. Using a simplified 3D model for the cosmic-ray propagation out from
the shell of the SNR, we consider whether the interaction between SNR G35.6-0.4
and the MCs nearby could give rise to the TeV emission of HESS J1858+020
without producing a GeV counterpart. If so, the pair of SNR/TeV source with no
GeV detection would be reminiscent of other similarly-aged SNRs, such as some
of the TeV hotspots near W28, for which cosmic-ray diffusion may be used to
explain their multi-frequency phenomenology. However, for HESS J1858+020, we
found that although the phase space in principle allows for such GeV--TeV
non-correlation to appear, usual and/or observationally constrained values of
the parameters (e.g., diffusion coefficients and cloud-SNR likely distances)
would disfavor it.Comment: In press in MNRA
Understanding hadronic gamma-ray emission from supernova remnants
We aim to test the plausibility of a theoretical framework in which the
gamma-ray emission detected from supernova remnants may be of hadronic origin,
i.e., due to the decay of neutral pions produced in nuclear collisions
involving relativistic nuclei. In particular, we investigate the effects
induced by magnetic field amplification on the expected particle spectra,
outlining a phenomenological scenario consistent with both the underlying
Physics and the larger and larger amount of observational data provided by the
present generation of gamma experiments, which seem to indicate rather steep
spectra for the accelerated particles. In addition, in order to study to study
how pre-supernova winds might affect the expected emission in this class of
sources, the time-dependent gamma-ray luminosity of a remnant with a massive
progenitor is worked out. Solid points and limitations of the proposed scenario
are finally discussed in a critical way.Comment: 30 pages, 5 figures; Several comments, references and a figure added.
Some typos correcte
G0.57-0.018: A young supernova remnant? INTEGRAL and VLA observations
We report INTEGRAL/IBIS gamma-ray and VLA radio observations of G0.570-0.018,
a diffuse X-ray source recently discovered by ASCA and Chandra in the Galactic
center region. Based on its spectrum and morphology, G0.570-0.018 has been
proposed to be a very young supernova remnant. In this scenario, the presence
of gamma-ray lines coming from the short-lived radioactive nucleus 44Ti as well
as synchrotron radio continuum emission are expected. The first could provide
informations on nucleosynthesis environments in the interior of exploding
stars, the latter could probe the interaction between the supernova blast wave
and the circumstellar/interstellar matter. We have not detected 44Ti lines nor
any conspicuous radio feature associated with this source down to the achieved
sensitivities. From the derived upper limits we set constraints on the nature
of G0.570-0.018.Comment: 17 pages, 4 figures, accepted for publication in Ap
The Impact II, a Very High-Resolution Quadrupole Time-of-Flight Instrument (QTOF) for Deep Shotgun Proteomics
Hybrid quadrupole time-of-flight (QTOF) mass spectrometry is one of the two major principles used in proteomics. Although based on simple fundamentals, it has over the last decades greatly evolved in terms of achievable resolution, mass accuracy, and dynamic range. The Bruker impact platform of QTOF instruments takes advantage of these developments and here we develop and evaluate the impact II for shotgun proteomics applications. Adaption of our heated liquid chromatography system achieved very narrow peptide elution peaks. The impact II is equipped with a new collision cell with both axial and radial ion ejection, more than doubling ion extraction at high tandem MS frequencies. The new reflectron and detector improve resolving power compared with the previous model up to 80%, i.e. to 40,000 at m/z 1222. We analyzed the ion current from the inlet capillary and found very high transmission (>80%) up to the collision cell. Simulation and measurement indicated 60% transfer into the flight tube. We adapted MaxQuant for QTOF data, improving absolute average mass deviations to better than 1.45 ppm. More than 4800 proteins can be identified in a single run of HeLa digest in a 90 min gradient. The workflow achieved high technical reproducibility (R2 > 0.99) and accurate fold change determination in spike-in experiments in complex mixtures. Using label-free quantification we rapidly quantified haploid against diploid yeast and characterized overall proteome differences in mouse cell lines originating from different tissues. Finally, after high pH reversed-phase fractionation we identified 9515 proteins in a triplicate measurement of HeLa peptide mixture and 11,257 proteins in single measurements of cerebellum-the highest proteome coverage reported with a QTOF instrument so far
Ocorrência de Trichospilus diatraeae (Hym.: Eulophidae) em broca-das-cucurbitáceas, no Brasil
Este trabalho tem como objetivo registrar a primeira ocorrência, no Brasil, do parasitóide de pupas Trichospilus diatraeae (Cherian & Margabandhu, 1942) (Hymenoptera: Eulophidae) na broca-das-cucurbitáceas, Diaphania hyalinata (L.) (Lepidoptera: Pyralidae). A espécie T. diatraeae já foi relatada no Brasil em pragas da gravioleira no Distrito Federal e eucalipto nos estados de Minas Gerais e São Paulo. No sistema produtivo da abóbora D. hyalinata é reconhecidamente uma praga importante por causar sérios prejuízos em função das injúrias provocadas em diferentes partes da planta. A ocorrência do parasitóide foi registrada em pupas coletadas no campo, localizado no campus experimental do Centro de Ciências Agrárias da Universidade Federal do Espírito Santo, no município de Alegre-ES.This study aims to record the first occurrence in Brazil of the parasitoid pupae Trichospilus diatraeae (Cherian & Margabandhu, 1942) (Hymenoptera: Eulophidae) on the melonworm, Diaphania hyalinata (L.) (Lepidoptera: Pyralidae). The specie T. diatraeae has been reported in pests of the soursop in the Distrito Federal, Brazil and eucalyptus in the Brazilian States of Minas Gerais and São Paulo. In the production system of pumpkin D. hyalinata is recognized as a significant pest which causes serious losses as a result of injuries caused in different parts of the plant. The occurrence of the parasitoid was recorded in pupae collected in the field, located on the campus of the Center of Agrarian Sciences, Federal University of Espirito Santo, Alegre Espirito Santo State, Brazil
Tenascin-C Enhances Pancreatic Cancer Cell Growth and Motility and Affects Cell Adhesion through Activation of the Integrin Pathway
Background: Pancreatic cancer (PDAC) is characterized by an abundant fibrous tissue rich in Tenascin-C (TNC), a large ECM glycoprotein mainly synthesized by pancreatic stellate cells (PSCs). In human pancreatic tissues, TNC expression increases in the progression from low-grade precursor lesions to invasive cancer. Aim of this study was the functional characterization of the effects of TNC on biologic relevant properties of pancreatic cancer cells. Methods: Proliferation, migration and adhesion assays were performed on pancreatic cancer cell lines treated with TNC or grown on a TNC-rich matrix. Stable transfectants expressing the large TNC splice variant were generated to test the effects of endogenous TNC. TNC-dependent integrin signaling was investigated by immunoblotting, immunofluorescence and pharmacological inhibition. Results: Endogenous TNC promoted pancreatic cancer cell growth and migration. A TNC-rich matrix also enhanced migration as well as the adhesion to the uncoated growth surface of poorly differentiated cell lines. In contrast, adhesion to fibronectin was significantly decreased in the presence of TNC. The effects of TNC on cell adhesion were paralleled by changes in the activation state of paxillin and Akt. Conclusion: TNC affects proliferation, migration and adhesion of poorly differentiated pancreatic cancer cell lines and migh
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