315 research outputs found

    Analysis of paternal lineages in Brazilian and African populations

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    The present-day Brazilian population is a consequence of the admixture of various peoples of very different origins, namely, Amerindians, Europeans and Africans. The proportion of each genetic contribution is known to be very heterogeneous throughout the country. The aim of the present study was to compare the male lineages present in two distinct Brazilian populations, as well as to evaluate the African contribution to their male genetic substrate. Thus, two Brazilian population samples from Manaus (State of Amazon) and Ribeirão Preto (State of São Paulo) and three African samples from Guinea Bissau, Angola and Mozambique were typed for a set of nine Y chromosome specific STRs. The data were compared with those from African, Amerindian and European populations. By using Y-STR haplotype information, low genetic distances were found between the Manaus and Ribeirão Preto populations, as well as between these and others from Iberia. Likewise, no significant distances were observed between any of the African samples from Angola, Mozambique and Guinea Bissau. Highly significant Rst values were found between both Brazilian samples and all the African and Amerindian populations. The absence of a significant Sub-Saharan African male component resulting from the slave trade, and the low frequency in Amerindian ancestry Y-lineages in the Manaus and Ribeirão Preto population samples are in accordance with the accentuated gender asymmetry in admixture processes that has been systematically reported in colonial South American populations

    Spatial distribution of arthropods on Acacia mangium (Fabales: Fabaceae) trees as windbreaks in the cerrado

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    Acacia mangium (Fabales: Fabaceae) is broadly used in restoration process of degraded lands in tropical and subtropical regions. Thus, our aim was to assess the spatial distribution of arthropods on tree crown (vertical- upper, median and lower canopy and horizontal north, south, east and west) and leaf surfaces (adaxial and abaxial) of A. mangium trees. Phytophagous arthropods and natural enemies were quantified biweekly in 20 trees during three years. The Shannon index (H’) of phytophagous insects were higher on the abaxial surface of leaves on branches facing the west side and basal thirds, while the lowest index was found on the adaxial surface of leaves on branches facing north and on trunk of A. mangium. The natural enemies and pollinators presented the highest H’ indexes on the abaxial surface of leaves on branches facing north on basal thirds of A. mangium, while the lowest index values were found on the adaxial surface of leaves on branches facing the other sides. Trigona spinipes Fabricius (Hymenoptera: Apidae, Meliponinae), Aethalion reticulatum (Hemiptera: Aetalionidae) and Pentatomidae sp.1 (Hemiptera) were the most abundant and with the lowest k-dominance on different parts of A. mangium trees. Camponotus sp.2 (Hymenoptera: Formicidae), Tetragonisca angustula (Latreille) (Hymenoptera: Apidae) and Polistes sp. (Hymenoptera: Vespidae) had higher abundance and lower k-dominance. These results may be a support for programs of pest control and maintenance of natural enemies and pollinators in future plantations of A. mangium. For instance, application of biopesticides may reach better results if aimed directly to the preferred sites of target organisms, beyond minimizing possible negative effects on non-target ones.Acacia mangium (Fabales: Fabaceae) es ampliamente utilizado en el proceso de restauración de las tierras degradadas en las regiones tropicales y subtropicales. Por lo tanto, nuestro objetivo fue evaluar la distribución espacial de los artrópodos en la copa del árbol (verticaldosel superior, medio e inferior y horizontal - norte, sur, este y oeste) y las superficies de las hojas (adaxial y abaxial) de A. mangium. Artrópodos fitófagos y enemigos naturales fueron cuantificados quincenalmente en 20 árboles durante tres años. El índice de Shannon (H’) de los insectos fitófagos fueron más altos en la superficie abaxial de las hojas en las ramas que se enfrenta el lado oeste y tercios basales, mientras que se encontró el índice más bajo en la superficie adaxial de las hojas en las ramas que dan al norte y en el tronco de A. mangium. Los enemigos naturales y polinizadores presentan los más altos índices H’ en la superficie abaxial de las hojas en las ramas que dan al norte en tercios basales de A. mangium, mientras que se encontraron los valores de los índices más bajos en la superficie adaxial de las ho- jas en las ramas que se enfrentan los otros lados. Trigona spinipes Fabricius (Hymenoptera: Apidae), Aethalion reticulatum (Hemiptera: Aetalionidae) y Pentatomidae sp.1 (Hemiptera) fueron las más abundantes y con el más bajo k-dominación en diferentes partes de A. mangium. Camponotus sp. 2 (Hymenoptera: Formicidae) , Tetragonisca angustula (Latreille) (Hymenoptera: Apidae) y Polistes sp. (Hymenoptera: Vespidae) presentó mayor abundancia y más bajo k-dominación. Estos resultados pueden ser un apoyo para los programas de con- trol de plagas y el mantenimiento de los enemigos naturales y polinizadores en las futuras plantaciones de A. mangium. Por ejemplo, la aplicación de biopesticidas puede alcanzar mejores resultados si dirigido directamente a los sitios preferidos de los organismos objetivo, más allá de minimizar los posibles efectos negativos en los que no va destinado

    A lean six sigma framework for continuous and incremental improvement in the oil and gas sector

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    This article aims to explore synergies between Lean Production (LP) and Six Sigma principles in order to propose a Lean Six Sigma (LSS) framework for continuous and incremental improvement in the oil and gas sector. The Three-Dimensional LSS Framework seeks to provide various combinations about the integration between LP principles, DMAIC cycle and PDCA cycle to support operations management needs. Design/methodology/approach - The research method is composed of two main steps: (i) diagnostic of current problems and proposition of a conceptual framework that qualitatively integrates synergistic aspects of LP and Six Sigma; and (ii) analysis of the application of the construct through semi-structured interviews with leaders from oil and gas companies to assess and validate the proposed framework. Findings - As a result, a conceptual framework of LSS is developed contemplating the integration of LP and Six Sigma and providing a systemic and holistic approach to problemsolving through continuous and incremental improvement in the oil and gas sector. Originality/value - This research is different from previous studies because it integrates LP principles, DMAIC and PDCA cycles into a unique framework that fulfils a specific need of oil and gas sector. It presents a customized LSS framework that guides wastes and costs reduction, while enhances quality and reduces process variability to elevate efficiency in operations management of this sector. The paper type is an original research that present new and original scientific findings.N/

    Reconstructing the Indian Origin and Dispersal of the European Roma: A Maternal Genetic Perspective

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    Previous genetic, anthropological and linguistic studies have shown that Roma (Gypsies) constitute a founder population dispersed throughout Europe whose origins might be traced to the Indian subcontinent. Linguistic and anthropological evidence point to Indo-Aryan ethnic groups from North-western India as the ancestral parental population of Roma. Recently, a strong genetic hint supporting this theory came from a study of a private mutation causing primary congenital glaucoma. In the present study, complete mitochondrial control sequences of Iberian Roma and previously published maternal lineages of other European Roma were analyzed in order to establish the genetic affinities among Roma groups, determine the degree of admixture with neighbouring populations, infer the migration routes followed since the first arrival to Europe, and survey the origin of Roma within the Indian subcontinent. Our results show that the maternal lineage composition in the Roma groups follows a pattern of different migration routes, with several founder effects, and low effective population sizes along their dispersal. Our data allowed the confirmation of a North/West migration route shared by Polish, Lithuanian and Iberian Roma. Additionally, eleven Roma founder lineages were identified and degrees of admixture with host populations were estimated. Finally, the comparison with an extensive database of Indian sequences allowed us to identify the Punjab state, in North-western India, as the putative ancestral homeland of the European Roma, in agreement with previous linguistic and anthropological studies

    Electronic and phononic states of the Holstein-Hubbard dimer of variable length

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    We consider a model Hamiltonian for a dimer including all the electronic one- and two-body terms consistent with a single orbital per site, a free Einstein phonon term, and an electron-phonon coupling of the Holstein type. The bare electronic interaction parameters were evaluated in terms of Wannier functions built from Gaussian atomic orbitals. An effective polaronic Hamiltonian was obtained by an unrestricted displaced-oscillator transformation, followed by evaluation of the phononic terms over a squeezed-phonon variational wave function. For the cases of quarter-filled and half-filled orbital, and over a range of dimer length values, the ground state was identified by simultaneously and independently optimizing the orbital shape, the phonon displacement and the squeezing effect strength. As the dimer length varies, we generally find discontinuous changes of both electronic and phononic states, accompanied by an appreciable renormalization of the effective electronic interactions across the transitions, due to the equilibrium shape of the wave functions strongly depending on the phononic regime and on the type of ground state.Comment: 11 pages, RevTeX, 10 PostScript figures; to appear in Phys. Rev.

    Two-dimensional SIR epidemics with long range infection

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    We extend a recent study of susceptible-infected-removed epidemic processes with long range infection (referred to as I in the following) from 1-dimensional lattices to lattices in two dimensions. As in I we use hashing to simulate very large lattices for which finite size effects can be neglected, in spite of the assumed power law p(x)xσ2p({\bf x})\sim |{\bf x}|^{-\sigma-2} for the probability that a site can infect another site a distance vector x{\bf x} apart. As in I we present detailed results for the critical case, for the supercritical case with σ=2\sigma = 2, and for the supercritical case with 0<σ<20< \sigma < 2. For the latter we verify the stretched exponential growth of the infected cluster with time predicted by M. Biskup. For σ=2\sigma=2 we find generic power laws with σ\sigma-dependent exponents in the supercritical phase, but no Kosterlitz-Thouless (KT) like critical point as in 1-d. Instead of diverging exponentially with the distance from the critical point, the correlation length increases with an inverse power, as in an ordinary critical point. Finally we study the dependence of the critical exponents on σ\sigma in the regime 0<σ<20<\sigma <2, and compare with field theoretic predictions. In particular we discuss in detail whether the critical behavior for σ\sigma slightly less than 2 is in the short range universality class, as conjectured recently by F. Linder {\it et al.}. As in I we also consider a modified version of the model where only some of the contacts are long range, the others being between nearest neighbors. If the number of the latter reaches the percolation threshold, the critical behavior is changed but the supercritical behavior stays qualitatively the same.Comment: 14 pages, including 29 figure

    Reconstructing Roma History from Genome-Wide Data

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    The Roma people, living throughout Europe and West Asia, are a diverse population linked by the Romani language and culture. Previous linguistic and genetic studies have suggested that the Roma migrated into Europe from South Asia about 1,000–1,500 years ago. Genetic inferences about Roma history have mostly focused on the Y chromosome and mitochondrial DNA. To explore what additional information can be learned from genome-wide data, we analyzed data from six Roma groups that we genotyped at hundreds of thousands of single nucleotide polymorphisms (SNPs). We estimate that the Roma harbor about 80% West Eurasian ancestry–derived from a combination of European and South Asian sources–and that the date of admixture of South Asian and European ancestry was about 850 years before present. We provide evidence for Eastern Europe being a major source of European ancestry, and North-west India being a major source of the South Asian ancestry in the Roma. By computing allele sharing as a measure of linkage disequilibrium, we estimate that the migration of Roma out of the Indian subcontinent was accompanied by a severe founder event, which appears to have been followed by a major demographic expansion after the arrival in Europe.Országos Tudományos Kutatási Alapprogramok (OTKA K 103983)Országos Tudományos Kutatási Alapprogramok (OTKA 73430)National Science Foundation (U.S.) (HOMINID grant 1032255)National Institutes of Health (U.S.) (grant GM100233

    A integração de cultivos, criações e extrativismo pela família Cordeiro: São José dos Mouras, Lima Campos, MA.

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