775 research outputs found

    Domestication and Dispersal of Native Crops in Amazonia

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    Recent decades have witnessed the rapid expansion of interest in and research on the domestication of crop plants worldwide. These species are the basis of the rise to dominance of Homo sapiens over the last 10,000 years. New techniques in archaeology and the expansion of molecular genetics are uncovering abundant evidence to support or refute old hypotheses about human domestication of crops and creation of food production systems that fueled population expansions and linguistic diasporas, and to raise new hypotheses. In Amazonia and elsewhere in lowland South America, archaeologists are starting to examine these hypotheses in earnest, and geneticists are starting to generate data to identify crop origins and dispersals. Archaeologists now generally agree that Amazonia was inhabited by numerous advanced societies before European conquest, especially along the major white water rivers and in other favorable locations for food production, and that these societies had domesticated significant areas of numerous landscapes. This special section of Tipití summarizes a set of presentations given during the recent 2nd International Meeting on Amazonian Archaeology, held in Manaus, Amazonas, in September 2010. An overview of plant domestication opens the sequence, followed by new archaeobotanical evidence from the southeastern Colombian and central Brazilian Amazonia and from the southern savannas of Brazil, and new molecular genetic evidence about the origins of peach palm (Bactris gasipaes) and the dispersal of manioc (Manihot esculenta), maize (Zea mays), and peach palm in lowland South America

    RHETT2/EPDM Hall Thruster Propulsion System Electromagnetic Compatibility Evaluation

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    Electromagnetic compatibility measurements were obtained as part of the Electric Propulsion Demonstration Module (EPDM) flight qualification program. Tests were conducted on a Hall thruster system operating at a nominal 66O W discharge power. Measurements of conducted and radiated susceptibility and emissions were obtained and referenced to MEL-STD-461 C. The power processor showed some conducted susceptibility below 4 kHz for the magnet current and discharge voltage. Radiated susceptibility testing yielded a null result. Conducted emissions showed slight violations of the specified limit for MIL-461C CE03. Radiated emissions exceeded the RE02 standard at low frequencies, below 300 MHz, by up to 40 dB RV/m/MHz

    Modelando a distribuição espacial da endêmica e ameaçada palmeira Syagrus glaucescens (Arecaceae)

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    This study tests the use of accessible geoprocessing techniques to identify and describe the distribution of Syagrus glaucescens, a threatened palm shrub endemic to rupestrian fields (high-altitude grasslands) of the southern Espinhaço Range, in Minas Gerais, Brazil. A hundred and ninety five occurrence points and 24 absence points of S. glaucescens were recorded on a GPS device during field trips. Free databases of eight abiotic variables for the surveyed area were also used. Ninety-eight of the occurrence points were used to generate a spectral signature in ArcView to identify variables best characterizing S. glaucescens’ distribution area and produce a probability map. The species’ distribution was strongly associated to rocky outcrops whose geological composition is Quartzite Filite and Conglomerates, above 1.000 m of altitude, with declivities of 5-30%. When the accuracy of the probability map was tested, 87.63% of the 97 occurrence points used fitted areas of very high occurrence probability on the map, while 100% of the 24 non-occurrence points matched areas of null probability; therefore confirming the high accuracy of the model in predicting the occurrence of S. glaucescens. Although the altitudinal grasslands of Espinhaço are areas of great biodiversity and high degree of plant species endemism, they remain poorly studied. Thus, this model can be a helpful tool in designing management and conservation strategies not only for S. glaucescens but also for other species associated to rocky outcrops of such environment.Key words: rupestrian fields, rocky outcrops, habitat modeling.O presente estudo testou a utilização de ferramentas acessíveis de geoprocessamento na identificação e caracterização das áreas de ocorrência da palmeira Syagrus glaucescens, uma espécie de palmeira ameaçada de extinção e endêmica dos campos rupestres da Cadeia do Espinhaço de Minas Gerais, Brasil. Cento e noventa e cinco pontos de ocorrência e 24 pontos de ausência de S. glaucescens foram registrados com um GPS. Bases gratuitas de oito variáveis abióticas da área estudada também foram usadas. Noventa e oito dos pontos de ocorrência foram utilizados para gerar uma assinatura espectral no ArcView para identificar as variáveis que melhor caracterizassem a área de distribuição de S. glaucescens e produzir um mapa de probabilidades. Observou-se uma maior distribuição da espécie em áreas de afloramentos rochosos com composição geológica Quartzito Filito Metaconglomerados, acima de 1000 m de altitude e com declividade entre 5 e 30%. Quando testado o potencial preditivo do mapa de probabilidades, obteve-se 87,63% dos 97 pontos de ocorrência encontrados em áreas de altíssima probabilidade, enquanto que 100% dos 24 pontos de não ocorrência enquadrou-se em áreas de probabilidade nula, confirmando assim a alta eficácia do modelo em predizer as áreas de ocorrência da espécie. Embora os campos rupestres da Cadeia do Espinhaço sejam áreas de grande biodiversidade e alto grau endemismo de espécies de plantas, permanecem pouco estudados. Este modelo pode ser uma ferramenta útil para o delineamento de estratégias de manejo e conservação não apenas para S. glaucescens como também para outras espécies associadas a afloramentos rochosos de tal ambiente.Palavras-chave: campos rupestres, afloramentos rochosos, modelagem de hábitat

    Exploring New Physics in the C7-C7' plane

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    The Wilson coefficient C7 governing the radiative electromagnetic decays of B meson has been calculated to a very high accuracy in the Standard Model, but experimental bounds on either the magnitude or the sign of C7 are often model-dependent. In the present paper, we attempt at constraining both the magnitude and sign of C7 using a systematic approach. We consider already measured observables like the branching ratios of B \rightarrow Xs mu+ mu- and B \rightarrow Xs gamma, the isospin and CP asymmetries in B \rightarrow K* gamma, as well as AFB and FL in B \rightarrow K*l+l-. We also discuss the transverse observable AT2 which, once measured, may help to disentangle some of the scenarios considered. We explore the constraints on C7, C9, C10 as well as their chirality-flipped counterparts. Within our framework, we find that we need to extend the constraints up to 1.6 sigma to allow for the "flipped-sign solution" of C7. The SM solution for C7 exhibits a very mild tension if New Physics is allowed in dipole operators only. We provide semi-numerical expressions for all these observables as functions of the relevant Wilson coefficients at the low scale.Comment: 54 pages, 16 figures, 15 tables. Normalization factor introduced for the integrated AFB and FL in Sec.2.5 (Eq.2.35-2.38). Conclusions unchanged. Not updated in JHE

    Abnormal thyroid hormone status differentially affects bone mass accrual and bone strength in C3H/HeJ mice: a mouse model of type I deiodinase deficiency

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    C3H/HeJ (C3H) mice are deficient of type I deiodinase (D1), an enzyme that activates thyroid hormone (TH), converting thyroxine (T4) to triiodothyronine (T3). Nevertheless, C3H mice present normal serum T3 and a gross euthyroid phenotype. To investigate if a global D1 deficiency interferes in the TH effects on bone, we compared bone growth, bone mass accrual and bone strength of C3H and C57BL/6J (B6) mice under abnormal TH status. Four-week-old female mice of both strains were grouped as Euthyroid, Hypothyroid (pharmacologically-induced), 1xT4 and 10xT4 (hypothyroid animals receiving 1- or 10-fold the physiological dose of T4 /day/16 weeks). Hypothyroidism and TH excess similarly impaired body weight (BW) gain and body growth in both mice strains. In contrast, whereas hypothyroidism only slightly impaired bone mineral density (BMD) accrual in B6 mice, it severely impaired BMD accrual in C3H mice. No differences were observed in serum and bone concentrations of T3 between hypothyroid animals of both strains. Interestingly, treatment with 10xT4 was less deleterious to BMD accrual in C3H than in B6 mice and resulted in less elevated T3 serum levels in B6 than in C3H mice, which is probably explained by the lower D1 activity in C3H mice. In addition, hypothyroidism decreased bone strength only in C3H but not in B6 mice, while TH excess decreased this parameter in both strains. These findings indicate that D1 deficiency contributes to the TH excess-induced differences in bone mass accrual in C3H vs. B6 mice and suggest that deiodinase-unrelated genetic factors might account for the different skeleton responses to hypothyroidism between strains

    Data standardization of plant-pollinator interactions

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    Background: Animal pollination is an important ecosystem function and service, ensuring both the integrity of natural systems and human well-being. Although many knowledge shortfalls remain, some high-quality data sets on biological interactions are now available. The development and adoption of standards for biodiversity data and metadata has promoted great advances in biological data sharing and aggregation, supporting large-scale studies and science-based public policies. However, these standards are currently not suitable to fully support interaction data sharing. Results: Here we present a vocabulary of terms and a data model for sharing plant–pollinator interactions data based on the Darwin Core standard. The vocabulary introduces 48 new terms targeting several aspects of plant–pollinator interactions and can be used to capture information from different approaches and scales. Additionally, we provide solutions for data serialization using RDF, XML, and DwC-Archives and recommendations of existing controlled vocabularies for some of the terms. Our contribution supports open access to standardized data on plant–pollinator interactions. Conclusions: The adoption of the vocabulary would facilitate data sharing to support studies ranging from the spatial and temporal distribution of interactions to the taxonomic, phenological, functional, and phylogenetic aspects of plant–pollinator interactions. We expect to fill data and knowledge gaps, thus further enabling scientific research on the ecology and evolution of plant–pollinator communities, biodiversity conservation, ecosystem services, and the development of public policies. The proposed data model is flexible and can be adapted for sharing other types of interactions data by developing discipline-specific vocabularies of terms.Fil: Salim, José A. Universidade de Sao Paulo; BrasilFil: Saraiva, Antonio M.. Universidade de Sao Paulo; BrasilFil: Zermoglio, Paula Florencia. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Patagonia Norte. Instituto de Investigaciones En Recursos Naturales, Agroecologia y Desarrollo Rural. - Universidad Nacional de Rio Negro. Instituto de Investigaciones En Recursos Naturales, Agroecologia y Desarrollo Rural.; ArgentinaFil: Agostini, Kayna. Universidade Federal do São Carlos; BrasilFil: Wolowski, Marina. Universidade Federal de Alfenas; BrasilFil: Drucker, Debora P.. Empresa Brasileira de Pesquisa Agropecuaria (embrapa);Fil: Soares, Filipi M.. Universidade de Sao Paulo; BrasilFil: Bergamo, Pedro J.. Jardim Botânico do Rio de Janeiro; BrasilFil: Varassin, Isabela G.. Universidade Federal do Paraná; BrasilFil: Freitas, Leandro. Jardim Botânico do Rio de Janeiro; BrasilFil: Maués, Márcia M.. Empresa Brasileira de Pesquisa Agropecuaria (embrapa);Fil: Rech, Andre R.. Universidade Federal dos Vales do Jequitinhonha e Mucuri; BrasilFil: Veiga, Allan K.. Universidade de Sao Paulo; BrasilFil: Acosta, Andre L.. Instituto Tecnológico Vale; BrasilFil: Araujo, Andréa C. Universidade Federal do Mato Grosso do Sul; BrasilFil: Nogueira, Anselmo. Universidad Federal do Abc; BrasilFil: Blochtein, Betina. Pontificia Universidade Católica do Rio Grande do Sul; BrasilFil: Freitas, Breno M.. Universidade Estadual do Ceará; BrasilFil: Albertini, Bruno C.. Universidade de Sao Paulo; BrasilFil: Maia Silva, Camila. Universidade Federal Rural Do Semi Arido; BrasilFil: Nunes, Carlos E. P.. University of Stirling; BrasilFil: Pires, Carmen S. S.. Empresa Brasileira de Pesquisa Agropecuaria (embrapa);Fil: Dos Santos, Charles F.. Pontificia Universidade Católica do Rio Grande do Sul; BrasilFil: Queiroz, Elisa P.. Universidade de Sao Paulo; BrasilFil: Cartolano, Etienne A.. Universidade de Sao Paulo; BrasilFil: de Oliveira, Favízia F. Universidade Federal da Bahia; BrasilFil: Amorim, Felipe W.. Universidade Estadual Paulista Julio de Mesquita Filho; BrasilFil: Fontúrbel, Francisco E.. Pontificia Universidad Católica de Valparaíso; ChileFil: da Silva, Gleycon V.. Ministério da Ciência, Tecnologia, Inovações. Instituto Nacional de Pesquisas da Amazônia; BrasilFil: Consolaro, Hélder. Universidade Federal de Catalão; Brasi
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