Avaliação de clones de cupuaçuzeiro em ambiente de pesquisa participativa.

A elevada variabilidade fenotípica observada nos plantios comerciais do Estado do Pará, proporciona uma excelente oportunidade para seleção de materiais superiores. Há necessidade de identificar as matrizes potencialmente promissoras nos pomares comerciais, multiplica-las e avalia-las em delineamento experimental, para definir as que verdadeiramente apresentam características genotípicas para serem aproveitadas nos programas de melhoramento do cupuaçuzeiro. O objetivo desta pesquisa foi avaliar matrizes de cupuaçuzeiro, multiplicadas vegetativamente, em um ambiente de pesquisa participativa, visando identificar materiais promissores e adaptados às condições do Estado do Pará. Foram testados 25 clones originários de matrizes identificadas em pomares comerciais do município de Tomé Açu. O experimento foi instalado no delineamento experimental de blocos casualizados, com 25 tratamentos e cinco repetições com três plantas na parcela. Foram coletados dados de desenvolvimento vegetativo inicial, número de frutos produzidos por planta em quatro safras, bem como, plantas afetadas pela vassoura de bruxa. Os resultados revelaram grande variabilidade entre os clones, tanto para desenvolvimento vegetativo quanto para a produção de frutos. Alguns materiais tiveram comportamento destacado como o clone 7, seguido pelos clones 4, 3, 6, 15, 24, 25, 9, 14 e 17. Ficaram também evidenciadas as vantagens da parceria com o setor produtivo, em pesquisas dessa natureza.PIBIC-2011

Modification of cluster radio halo appearance by the thermal Sunyaev-Zeldovich effect

We discuss the consequences of the spectral and morphological modification of galaxy cluster radio halos due to the Sunyaev-Zeldovich (SZ) effect for the interpretation of existing and upcoming high frequency radio observations. Likely these modifications have affected the interpretation of the existing Coma cluster radio data. The radio halo emission visible at low (< 5 GHz) frequencies is at higher (> 10 GHz) frequencies completely over-compensated by the thermal SZ decrement. Thus, the total radio emission of a galaxy cluster goes through zero (in comparison to the constant cosmic microwave background (CMB) emission) at a frequency of several GHz. Since the radio halo brightness has a narrow radial profile compared to the SZ decrement, a central emission region is surrounded by a decrement within the intermediate frequency range of several GHz. The size of this emission regions shrinks with increasing frequency until the decrement dominates everywhere in the cluster.Comment: accepted by A&A Letters, 4 pages, 3 figurs, typo correcte

Genotipagem de plantas de cupuaçuzeiro, obtidas de uma população contrastante para resistência a Moniliophthora perniciosa, para a identificação de QRL's.

O mapeamento molecular visando à identificação de locos quantitativos associados à resistência a patógenos é uma ferramenta que poderá ser muito útil ao programa de melhoramento do cupuaçuzeiro. O objetivo desta pesquisa foi realizar a primeira etapa para identificar locus controladores de resistência à vassoura de bruxa, efetuando a genotipagem de uma família cujos pais apresentavam resistência contrastante àquela enfermidade. Para a obtenção da progênie foram realizadas polinizações controladas entre os clones 174 (resistente) e 1074 (susceptível). Obtida a família com 200 indivíduos, foi feita a extração do DNA de tecido foliar, e o teste dos primers. Foram testados 31 primers microssatélites de cacaueiro e 42 de cupuaçuzeiro. Dos quais foram selecionados 16 primers, sendo 10 de cacau e 6 cupuaçuzeiro, que demonstraram boa amplificação e polimorfismo. Foi obtido um total de 36 alelos, com média de 2,25 alelos/loco, sendo 3 o máximo de alelos por loco. O fingerprint de cada indivíduo será utilizado para a elaboração dos mapas de ligação.PIBIC-2011

Nonthermal Bremsstrahlung and Hard X-ray Emission from Clusters of Galaxies

We have calculated nonthermal bremsstrahlung (NTB) models for the hard X-ray (HXR) tails recently observed by BeppoSAX in clusters of galaxies. In these models, the HXR emission is due to suprathermal electrons with energies of about 10-200 keV. Under the assumption that the suprathermal electrons form part of a continuous spectrum of electrons including highly relativistic particles, we have calculated the inverse Compton (IC) extreme ultraviolet (EUV), HXR, and radio synchrotron emission by the extensions of the same populations. For accelerating electron models with power-law momentum spectra (N[p] propto p^{- mu}) with mu <~ 2.7, which are those expected from strong shock acceleration, the IC HXR emission exceeds that due to NTB. Thus, these models are only of interest if the electron population is cut-off at some upper energy <~1 GeV. Similarly, flat spectrum accelerating electron models produce more radio synchrotron emission than is observed from clusters if the ICM magnetic field is B >~ 1 muG. The cooling electron model produces vastly too much EUV emission as compared to the observations of clusters. We have compared these NTB models to the observed HXR tails in Coma and Abell 2199. The NTB models require a nonthermal electron population which contains about 3% of the number of electrons in the thermal ICM. If the suprathermal electron population is cut-off at some energy above 100 keV, then the models can easily fit the observed HXR fluxes and spectral indices in both clusters. For accelerating electron models without a cutoff, the electron spectrum must be rather steep >~ 2.9.Comment: Accepted for publication in the Astrophysical Journal. 10 pages with 5 embedded Postscript figures in emulateapj.sty. An abbreviated abstract follow

An unlikely radio halo in the low X-ray luminosity galaxy cluster RXC J1514.9-1523

We report the discovery of a giant radio halo in the galaxy cluster RXC J1514.9-1523 at z=0.22 with a relatively low X-ray luminosity, $L_{X \, [0.1-2.4 \rm \, kev]} \sim 7 \times 10^{44}$ erg s$^{-1}$. This faint, diffuse radio source is detected with the Giant Metrewave Radio Telescope at 327 MHz. The source is barely detected at 1.4 GHz in a NVSS pointing that we have reanalyzed. The integrated radio spectrum of the halo is quite steep, with a slope \alpha = 1.6 between 327 MHz and 1.4 GHz. While giant radio halos are common in more X-ray luminous cluster mergers, there is a less than 10% probability to detect a halo in systems with L_X \ltsim 8 \times 10^{44} erg s$^{-1}$. The detection of a new giant halo in this borderline luminosity regime can be particularly useful for discriminating between the competing theories for the origin of ultrarelativistic electrons in clusters. Furthermore, if our steep radio spectral index is confirmed by future deeper radio observations, this cluster would provide another example of the recently discovered population of ultra-steep spectrum radio halos, predicted by the model in which the cluster cosmic ray electrons are produced by turbulent reacceleration.Comment: 4 pages, 2 figures - Accepted for publication on A&A Research Note

Three-Dimensional Doppler Tomography of the RS Vulpeculae Interacting Binary

Three-dimensional Doppler tomography has been used to study the H$\alpha$ emission sources in the RS Vulpeculae interacting binary. The 2D tomogram of this binary suggested that most of the emission arose from the cool mass losing star with additional evidence of gas flowing close to the predicted trajectory. However, the 3D tomogram revealed surprising evidence of a more pronounced gas stream flow at high $V_z$ velocities from -240 to -360 km s{$^{-1}$}. This behavior is most likely caused by magnetic activity on the cool star since the central velocity plane, defined by $V_z$ = 0 km s{$^{-1}$}, should be coincident with the orbital plane of the binary if the flow is dominated by gravitational forces only. RS Vul has been detected as both an X-ray and a radio source, and it is possible that the RS Vul gas stream may have been deflected by magnetic field lines. This flow is distinctly different from that found in the streamlike state of U CrB, in which the gas flow was confined mostly to the central velocity plane.Comment: 12 pages, 7 figures, submitted to Ap

Chandra measurements of non-thermal-like X-ray emission from massive, merging, radio-halo clusters

We report the discovery of spatially-extended, non-thermal-like emission components in Chandra X-ray spectra for five of a sample of seven massive, merging galaxy clusters with powerful radio halos. The emission components can be fitted by power-law models with mean photon indices in the range 1.5 < Gamma < 2.0. A control sample of regular, dynamically relaxed clusters, without radio halos but with comparable mean thermal temperatures and luminosities, shows no compelling evidence for similar components. Detailed X-ray spectral mapping reveals the complex thermodynamic states of the radio halo clusters. Our deepest observations, of the Bullet Cluster 1E 0657-56, demonstrate a spatial correlation between the strongest power-law X-ray emission, highest thermal pressure, and brightest 1.34GHz radio halo emission in this cluster. We confirm the presence of a shock front in the 1E 0657-56 and report the discovery of a new, large-scale shock front in Abell 2219. We explore possible origins for the power-law X-ray components. These include inverse Compton scattering of cosmic microwave background photons by relativistic electrons in the clusters; bremsstrahlung from supra-thermal electrons energized by Coulomb collisions with an energetic, nonthermal proton population; and synchrotron emission associated with ultra-relativistic electrons. Interestingly, we show that the power-law signatures may also be due to complex temperature and/or metallicity structure in clusters particularly in the presence of metallicity gradients. In this case, an important distinguishing characteristic between the radio halo clusters and control sample of predominantly cool-core clusters is the relatively low central X-ray surface brightness of the former.Comment: Accepted for publication in MNRAS (24 pages, 13 figures). Improved discussion includes a new, possible explanation for `soft excess' X-ray emission from clusters as an artifact of metallicity/temperature structure and projection effects. Other physical explanations for the observed non-thermal-like X-ray emission also remai