1,800 research outputs found
Regular string-like braneworlds
In this work, we propose a new class of smooth thick string-like braneworld
in six dimensions. The brane exhibits a varying brane-tension and an
asymptotic behavior. The brane-core geometry is parametrized by the Bulk
cosmological constant, the brane width and by a geometrical deformation
parameter. The source satisfies the dominant energy condition for the
undeformed solution and has an exotic asymptotic regime for the deformed
solution. This scenario provides a normalized massless Kaluza-Klein mode for
the scalar, gravitational and gauge sectors. The near-brane geometry allows
massive resonant modes at the brane for the state and nearby the brane for
.Comment: 14 pages, 12 figures. Some modifications to match the published
version in EPJ
Relative timing of transcurrent displacements in northern Gondwana: U-Pb laser ablation ICP-MS zircon and monazite geochronology of gneisses and sheared granites from the western Iberia Massif (Portugal)
The Variscan belt of Western and Central Europe was formed by the oblique subduction of the Rheic Ocean and the collision of Laurussia with Gondwana during the Late Palaeozoic. We present field relationships and new U–Pb LA-ICP-MS zircon and monazite ages for Variscan gneisses and granites from a key section of the western Iberian Massif. The Martinchel section records the interplay of two kilometre-scale Variscan transcurrent shear zones active in the Gondwana basement of Pangaea: the Porto–Tomar fault zone (PTFZ) and the Coimbra–Córdoba shear zone (CCSZ). Different kinematic models have been invoked to explain the formation and evolution of these major Variscan structures mainly based on assumptions made in the absence of reliable radiometric ages. We show that: (1) ductile deformation and metamorphism were active in the CCSZ during the Visean–Serpukhovian (c.335–318 Ma) and created conditions for amphibolite facies metamorphism and coeval emplacement of granites; and (2) later ductile–brittle deformation related to dextral movements along the PTFZ overprinted the earlier foliation and folds derived from the CCSZ deformation, and deformed the previously intruded granites. U–Pb dating of zircon and monazites yield c.335 Ma ages for the ductile deformation developed under amphibolite facies metamorphic conditions in the Martinchel gneisses of the CCSZ. The gneisses were intruded by granites at c.335–318 Ma, and both were later deformed under ductile–brittle conditions by dextral motion on the PTFZ. The geometry of the Martinchel gneisses (typical of the CCSZ) changed from one of thrusting to one of normal faulting by refolding of the early foliation, stretching lineation and asymmetric structures related to the later PTFZ dextral shear episode. This pattern of interference is not fully considered in previous models and may lead to incorrect tectonic interpretations. According to our data and recently published ages, we suggest that the PTFZ was active after the Serpukhovian–Kasimovian since the c.318–308 Ma granites are deformed by north–south (170°) dextral shear planes. These data are critical to the interpretation of large-scale Carboniferous transcurrent displacements in northern Gondwana (Iberian Massif), and bear upon global models of crustal deformation that emphasize the importance of long-lived dextral movements during the collision between northern Gondwana and Laurussia following the closure of the Rheic Ocean
. U-Pb detrital zircon ages from the Beiras Group: Implications for the Neoproterozoic evolution of the SW Iberia
U-Pb detrital zircon ages from the Beiras Group greywackes (SW Central Iberian Zone - CIZ) indicate a maximum
depositional age of late Ediacaran (c. 560-578 Ma). Two salient features distinguish the Beiras Group from the Série
Negra greywackes (age equivalent from the Ossa-Morena Zone - OMZ): i) The presence of Tonian and
Mesoproterozoic (<8%) age clusters in the Beiras Group greywackes, that are almost absent in the OMZ, imply either a
distinct or an additional source of detrital zircons from the West African Craton; and 2) The higher content of Cryogenian
zircon ages of the Beiras Group greywackes (mainly at c. 840-750 Ma and c. 685-660 Ma), that contrast with the
dominant Ediacaran zircon ages of the Série Negra greywackes (OMZ). The Cryogenian zircon forming events that are
dominant in the SW CIZ basins are probably related to a different source with early Cadomian juvenile crust (c. 700-635
Ma) and with a possible contribution of the Pan-African suture (c. 850-700 Ma). The Nd isotopic signatures support the
addition of a juvenile source to pre-existent older crust for the Beiras Group metasediments. Although the Beiras Group
(SW CIZ) and Serie Negra (OMZ) late Ediacaran basins have evolved together in the active margin of Gondwana, they
were sufficiently separated to account for the differences in their detrital zircon content and isotopic signatures
Saúde, meio ambiente e condições sanitárias em São José de Ubá, como fatores de sustentabilidade.
O levantamento socioeconômico previsto no projeto Gestão Participativa da Microbacia Hidrográfica do Rio São Domingos - GEPAR-MBH utilizou uma abordagem participativa, de forma a engajar as comunidades locais na pesquisa de sua realidade, e possibilitar uma efetiva ação para a melhoria de seus problemas. Nesta abordagem, o desenvolvimento comunitário é um dos pilares do desenvolvimento sustentável. Considera-se que uma comunidade consciente e organizada estará capacitada a utilizar, de forma igualmente organizada, seus recursos naturais, minimizando a pressão sobre o meio. Nesse sentido, aplicou-se um questionário abrangente, e foi possível verificar o quanto as questões de saúde, meio ambiente e condições sanitárias eram relevantes, tanto para as questões práticas da vida quotidiana das comunidades, quanto para a compreensão técnico-científica dos processos sociais rurais que afetam a microbacia em questão. Com o tratamento estatístico dos dados e a discussão de seus resultados, observou-se diversas necessidades, as quais puderam ser incorporadas à caracterização socioeconômica. Em coerência com o enfoque participativo, os resultados foram transmitidos às lideranças das vilas trabalhadas, onde, nesse e em outros pontos, observa-se um incremento de seu protagonismo, na busca de melhores condições de vida, em sintonia com a preservação do meio ambiente.bitstream/CNPS-2010/14912/1/bpd-77-saude-sao-jose-uba.pd
Frequência do gênero de Stylosanthes e atributos físicos do solo no Semiárido baiano-Ba.
O objetivo deste trabalho foi avaliar a frequência de ocorrência do gênero de Stylosanthes e os atributos físicos do solo na mircrorregião de Juazeiro (Mrg-Jz) e no Território do Sisal (Tr-Ss) no Estado da Bahia - BA, em 30 municípios nestas duas regiões supracitadas, aonde foram realizados o levantamento florístico dos acessos do gênero de Stylosanthes nativo, seguido por coleta de solo na profundidade 0-20 em, apenas nos locais de coleta com presença de acessos. Foram verificados a ocorrência do gênero em 77,34% (Mrg-Jz) e 89,00% (Tr-Ss) dos pontos georeferenciados e, destes, com a predominância.de um ou dois acessos por ponto de coleta, numa altitude entre 300 a 499m, em ambas a regiões. Quanto aos atributos do solo, a textura predominante o tipo de solos arenoso, com a densidade do solo (Ds) classificado como crítico e com baixa porosidade total (PT) e teor de matéria orgânica (MO), aquém do ideal, indicando características de solos degradados. Já para densidade de partícula (Dp), em ambas as regiões de estudo, estão dentro do esperado para solos arenosos. A vegetação predominante no local de coleta dos acessos do Stylosanthes foi a Caatinga. Constatou-se uma elevada presença do gênero Stylosanthes na região Semiárida da Bahia vegetando em solos com atributos físicos com elevada, limitação e/ou já degradados
Microspatial Distributional Patterns of Vectors of Cutaneous Leishmaniasis in Pernambuco, Northeastern Brazil
This is the publisher's version, also available electronically from http://www.hindawi.com/journals/jtm/2012/642910/abs/The purpose of this study is to analyze the spatial distribution and population trends through time of Lutzomyia species in a long-term focus of cutaneous leishmaniasis transmission in an Atlantic Forest area, northeastern Brazil. Sand fly populations of different ecological niches were monitored spatiotemporally in 2009. To summarize vegetation characteristics and phenology, we calculated the Normalized Difference Vegetation Index from Landsat images. Using niche modeling approaches, we assessed suites of environmental factors to identify areas of transmission risk. Although 12 species were detected, L. whitmani was the most abundant and broadly distributed across the area, particularly in peridomiciliary locations, and associated negatively with denser vegetation areas. On the other hand, L. complexa, L. sordelli, and L. tupynambai were found almost exclusively in forested areas ( < 0 . 0 5 ), and associated positively with denser vegetation. Lutzomyia species' occurrences are related to specific environmental combinations (with contrast among species) in the region
IL18 gene polymorphism and its influence on CD4+ T-cell recovery in HIV-positive patients receiving antiretroviral therapy
Background: Pyroptosis has been reported to be critical in human immunodeficiency virus type 1 (HIV-1) pathogenesis and acquired immunodeficiency syndrome (AIDS) progression. Even after achieving viral suppression to undetectable levels during antiretroviral therapy (ART), exacerbated CD4+ T-cell death by pyroptosis has been suggested as one of the main causes of immunological non-response. Thus, variants in genes of pyroptosis pathway were studied in individuals with poor CD4+ T-cell reconstitution under antiretroviral therapy against HIV-1. Methods: 248 virologically suppressed ART-treated patients, 126 immunological non-responders (INR) and 122 immunological responders (IR) were recruited. Genotyping was performed using TaqMan probe-based realtime PCR platform. Genotype-guided flow cytometry analysis with general and recent thymic emigrant (RTE) CD4+ T-cells in pyroptosis was performed based on associated polymorphisms. Results: Both IL18 rs187238 G allele and GG genotype were associated as protection factors against poor CD4+ T-cell recovery (OR = 0.22; 95%CI = 0.50\u20130.77; P =.010 and OR = 0.58; 95%CI = 0.36\u20130.93; P =.022, respectively). It was demonstrated a statistical association between IL18 rs187238 genotypes of ART-treated patients and death by Caspase-1 levels (P =.020). The GG genotype showed lower pyroptotic RTE CD4+ T-lymphocytes levels in the ART-treated groups comparing with CC (P =.029) and CG (P =.018) genotypes, suggesting that the G allele presence may be related to a lower IL-18 production and thus reduced dead CD4+ T-cells levels by Caspase-1. Conclusion: We observed that IL18 G variant allele and genotype were associated with a better immunological response, which may influence on immunological recovery of HIV-positive patients receiving antiretroviral therapy, and low Caspase-1 activity levels was observed on GG genotype when compared CC genotypes
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