229 research outputs found

    New measurement of neutron capture resonances of 209Bi

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    The neutron capture cross section of Bi209 has been measured at the CERN n TOF facility by employing the pulse-height-weighting technique. Improvements over previous measurements are mainly because of an optimized detection system, which led to a practically negligible neutron sensitivity. Additional experimental sources of systematic error, such as the electronic threshold in the detectors, summing of gamma-rays, internal electron conversion, and the isomeric state in bismuth, have been taken into account. Gamma-ray absorption effects inside the sample have been corrected by employing a nonpolynomial weighting function. Because Bi209 is the last stable isotope in the reaction path of the stellar s-process, the Maxwellian averaged capture cross section is important for the recycling of the reaction flow by alpha-decays. In the relevant stellar range of thermal energies between kT=5 and 8 keV our new capture rate is about 16% higher than the presently accepted value used for nucleosynthesis calculations. At this low temperature an important part of the heavy Pb-Bi isotopes are supposed to be synthesized by the s-process in the He shells of low mass, thermally pulsing asymptotic giant branch stars. With the improved set of cross sections we obtain an s-process fraction of 19(3)% of the solar bismuth abundance, resulting in an r-process residual of 81(3)%. The present (n,gamma) cross-section measurement is also of relevance for the design of accelerator driven systems based on a liquid metal Pb/Bi spallation target.Comment: 10 pages, 5figures, recently published in Phys. Rev.

    Inhibition of the platelet-derived growth factor receptor beta (PDGFRB) using gene silencing, crenolanib besylate, or imatinib mesylate hampers the malignant phenotype of mesothelioma cell lines

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    Malignant pleural mesothelioma (MPM) is a cancer of the pleural cavity resistant to chemotherapy. The identification of novel therapeutic targets is needed to improve its poor prognosis. Following a review of literature and a screening of specimens we found that platelet-derived growth factor receptor beta (PDGFRB) is over-expressed, but not somatically mutated, in MPM tissues. We aimed to ascertain whether PDGFRB is a MPM-cancer driver gene. The approaches employed included the use of gene silencing and the administration of small molecules, such as crenolanib and imatinib (PDGFR inhibitors) on MPM cell lines (IstMes2, Mero-14, Mero-25). Met5A cells were used as non-malignant mesothelial cell line. PDGFRB-silencing caused a decrease in the proliferation rate, and a reduced colony formation capacity, as well as an increase of the share of cells in sub-G1 and in G2 phase, and increased apoptotic rate of MPM cell lines. Loss of migration ability was also observed. Similar, or even further enhanced, results were obtained with crenolanib. Imatinib showed the least effective activity on the phenotype. In conclusion, our study highlights PDGFRB as target with a clear role in MPM tumorigenesis and provided a rationale to explore further the efficacy of crenolanib in MPM patients, with promising results

    A Functional Genomics Approach Identifies Candidate Effectors from the Aphid Species Myzus persicae (Green Peach Aphid)

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    Aphids are amongst the most devastating sap-feeding insects of plants. Like most plant parasites, aphids require intimate associations with their host plants to gain access to nutrients. Aphid feeding induces responses such as clogging of phloem sieve elements and callose formation, which are suppressed by unknown molecules, probably proteins, in aphid saliva. Therefore, it is likely that aphids, like plant pathogens, deliver proteins (effectors) inside their hosts to modulate host cell processes, suppress plant defenses, and promote infestation. We exploited publicly available aphid salivary gland expressed sequence tags (ESTs) to apply a functional genomics approach for identification of candidate effectors from Myzus persicae (green peach aphid), based on common features of plant pathogen effectors. A total of 48 effector candidates were identified, cloned, and subjected to transient overexpression in Nicotiana benthamiana to assay for elicitation of a phenotype, suppression of the Pathogen-Associated Molecular Pattern (PAMP)–mediated oxidative burst, and effects on aphid reproductive performance. We identified one candidate effector, Mp10, which specifically induced chlorosis and local cell death in N. benthamiana and conferred avirulence to recombinant Potato virus X (PVX) expressing Mp10, PVX-Mp10, in N. tabacum, indicating that this protein may trigger plant defenses. The ubiquitin-ligase associated protein SGT1 was required for the Mp10-mediated chlorosis response in N. benthamiana. Mp10 also suppressed the oxidative burst induced by flg22, but not by chitin. Aphid fecundity assays revealed that in planta overexpression of Mp10 and Mp42 reduced aphid fecundity, whereas another effector candidate, MpC002, enhanced aphid fecundity. Thus, these results suggest that, although Mp10 suppresses flg22-triggered immunity, it triggers a defense response, resulting in an overall decrease in aphid performance in the fecundity assays. Overall, we identified aphid salivary proteins that share features with plant pathogen effectors and therefore may function as aphid effectors by perturbing host cellular processes

    Resistindo ao desenvolvimento neocolonial: a luta do povo de Andalgalá contra projetos megamineiros

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    A América Latina vem experimentando uma nova era de declarada fé dos governos no mito do desenvolvimento, em articulação com a expansão de políticas extrativistas exportadoras em um contexto de renovada dependência. A face mais dramática do extrativismo na região tem sido a crescente presença de corporações mineiras transnacionais apoiadas por governos nacionais e regionais e por instituições internacionais financeiras e de apoio ao desenvolvimento, e intensamente resistidas por movimentos sociais populares. Neste artigo apresentamos o caso de Andalgalá (uma pequena cidade na Província de Catamarca, na Argentina) e as lutas do povo contra corporações mineiras transnacionais e seus aliados. Na tradição da Filosofia da Libertação e do método ana-dialético de Dussel, nos engajamos com o que tem sido denominado "comunidades argentinas do NÃO", expressando sua oposição a formas neocoloniais de desenvolvimento e gestão. Neste artigo estamos especificamente interessados em compreender como dois dispositivos gerencialistas usados pelas corporações mineiras, responsabilidade social corporativa (RSC) e pactos de governança, impactam a luta do povo. Acima de tudo, este artigo oferece instantâneos de batalhas na linha de frente do extrativismo. Esperamos ter dado voz àquelas pessoas que normalmente não são ouvidas, criando um espaço para suas visões sobre um tipo diferente de desenvolvimento.</jats:p

    The (n, gamma) campaigns at EXILL

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    At the PF1B cold neutron beam line at the Institut Laue Langevin, the EXILL array consisting of EXOGAM, GASP and ILL-Clover detectors was used to perform (n, gamma) measurements at very high coincidence rates. About ten different reactions were measured in autumn 2012 using a highly collimated cold neutron beam. In spring 2013, the EXOGAM array was combined with 16 LaBr3(Ce) scintillators in the EXILL&FATIMA campaign for the measurement of lifetimes using the generalised centroid difference method. We report on the properties of the set-ups and present first results from both campaigns

    Determination of the neutron fluence, the beam characteristics and the backgrounds at the CERN-PS TOF facility

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    Honey Bee PTEN – Description, Developmental Knockdown, and Tissue-Specific Expression of Splice-Variants Correlated with Alternative Social Phenotypes

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    Phosphatase and TENsin (PTEN) homolog is a negative regulator that takes part in IIS (insulin/insulin-like signaling) and Egfr (epidermal growth factor receptor) activation in Drosophila melanogaster. IIS and Egfr signaling events are also involved in the developmental process of queen and worker differentiation in honey bees (Apis mellifera). Here, we characterized the bee PTEN gene homologue for the first time and begin to explore its potential function during bee development and adult life.Honey bee PTEN is alternatively spliced, resulting in three splice variants. Next, we show that the expression of PTEN can be down-regulated by RNA interference (RNAi) in the larval stage, when female caste fate is determined. Relative to controls, we observed that RNAi efficacy is dependent on the amount of PTEN dsRNA that is delivered to larvae. For larvae fed queen or worker diets containing a high amount of PTEN dsRNA, PTEN knockdown was significant at a whole-body level but lethal. A lower dosage did not result in a significant gene down-regulation. Finally, we compared same-aged adult workers with different behavior: nursing vs. foraging. We show that between nurses and foragers, PTEN isoforms were differentially expressed within brain, ovary and fat body tissues. All isoforms were expressed at higher levels in the brain and ovaries of the foragers. In fat body, isoform B was expressed at higher level in the nurse bees.Our results suggest that PTEN plays a central role during growth and development in queen- and worker-destined honey bees. In adult workers, moreover, tissue-specific patterns of PTEN isoform expression are correlated with differences in complex division of labor between same-aged individuals. Therefore, we propose that knowledge on the roles of IIS and Egfr activity in developmental and behavioral control may increase through studies of how PTEN functions can impact bee social phenotypes
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