5,914 research outputs found

    Giant Effective G -factor In Pbx Eu1-x Te Epitaxial Films

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    We investigated Pbx Eu1-x Te films with x≀0.2 by magneto-optical measurements. For x∌0.01, the optical emission is similar to high quality EuTe films with two narrow lines attributed to excitonic recombinations associated with magnetic polarons. For increasing x, the emission becomes dominated by a broader lower energy band, which is very efficient as compared to the binary emission. The magneto-optical properties of the ternary films show various similarities with EuTe results, such as quenchings at similar temperatures and magnetic fields. Most remarkably, they also present a giant effective g -factor that makes this material a strong candidate for spintronic applications. © 2008 American Institute of Physics.933Mauger, A., Godart, C., (1986) Phys. Rep., 141, p. 51Masset, F., (1971) Phys. Rev. B, 3, p. 2364Akimoto, R., Kobayashi, M., Suzuki, T., (1994) J. Phys. Soc. Jpn., 63, p. 4616Heiss, W., Kirchschlager, R., Springholz, G., Chen, Z., Debnath, M., Oka, Y., (2004) Phys. Rev. B, 70, p. 035209Heiss, W., Prechtl, G., Springholz, G., (2001) Phys. Rev. B, 63, p. 165323Heiss, W., Prechtl, G., Springholz, G., (2001) Appl. Phys. Lett., 78, p. 3484Krenn, H., Herbst, W., Pascher, H., Ueta, Y., Springholz, G., Bauer, G., (1999) Phys. Rev. B, 60, p. 8117Springholz, G., Schwarzi, T., Aigle, M., Pascher, H., Heiss, W., (2000) Appl. Phys. Lett., 76, p. 1807Nolting, W., Mathi Jaya, S., Rex, S., (1996) Phys. Rev. B, 54, p. 14455Umehara, M., (2003) Phys. Rev. B, 68, p. 19320

    Agricultura familiar e agroindĂșstria canavieira: impasses sociais.

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    A PolĂ­tica AgroenergĂ©tica para produção de biocombustĂ­veis Ă© apresentada sob os pressupostos do desenvolvimento sustentĂĄvel. O ĂĄlcool, produzido a partir da cana-de-açĂșcar, aparece como a alternativa mais viĂĄvel, o que estimula a expansĂŁo e redistribuição espacial da produção canavieira. O estado de GoiĂĄs estĂĄ entre as principais rotas de ampliação da cana. O objetivo do artigo Ă© compreender o debate das questĂ”es sociais no plano dos discursos oficiais em torno do Plano Nacional de Agroenergia, bem como as contradiçÔes sociais associadas Ă  expansĂŁo da monocultura canavieira em regiĂ”es de predomĂ­nio da agricultura familiar. O desenvolvimento do tema baseou-se num estudo de caso, realizado no municĂ­pio de Itapuranga (GO), valendo-se de uma abordagem qualitativa e da combinação das tĂ©cnicas de pesquisa bibliogrĂĄfica, observação e, principalmente, entrevistas. Constatou-se que a expansĂŁo do cultivo da cana-de-açĂșcar contribuiu para transformar o contexto social de Itapuranga e provocar alteraçÔes considerĂĄveis na dinĂąmica produtiva e organizacional dos agricultores familiares

    Hypoxia and adipose tissue function and dysfunction in obesity

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    The rise in the incidence of obesity has led to a major interest in the biology of white adipose tissue. The tissue is a major endocrine and signalling organ, with adipocytes, the characteristic cell type, secreting a multiplicity of protein factors – the adipokines. Increases in the secretion of a number of adipokines occurs in obesity, underpinning inflammation in white adipose tissue and the development of obesity-associated diseases. There is substantial evidence, particularly from animal studies, that hypoxia develops in adipose tissue as the tissue mass expands, and the reduction in pO2 is considered to underlie the inflammatory response. Exposure of white adipocytes to hypoxic conditions in culture induces changes in the expression of >1,000 genes. The secretion of inflammation-related adipokines is up-regulated by hypoxia, and there is a switch from oxidative metabolism to anaerobic glycolysis. Glucose utilisation is increased in hypoxic adipocytes with corresponding increases in lactate production. Importantly, hypoxia induces insulin resistance in fat cells and leads to the development of adipose tissue fibrosis. Many of the responses of adipocytes to hypoxia are initiated at pO2 levels above the normal physiological range for adipose tissue. The other cell types within the tissue also respond to hypoxia, with the differentiation of preadipocytes to adipocytes being inhibited and preadipocytes being transformed into leptin-secreting cells. Overall, hypoxia has pervasive effects on the function of adipocytes and appears to be a key factor in adipose tissue dysfunction in obesity

    Unrelated Cord Blood Transplantation for Acute Leukemia Diagnosed in the First Year of Life: Outcomes and Risk Factor Analysis

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    Infant acute leukemia still has a poor prognosis, and allogeneic hematopoietic stem cell transplantation is indicated in selected patients. Umbilical cord blood (UCB) is an attractive cell source for this population because of the low risk of chronic graft-versus-host disease (GVHD), the strong graft-versus-leukemia effect, and prompt donor availability. This retrospective, registry-based study reported UCB transplantation (UCBT) outcomes in 252 children with acute lymphoblastic leukemia (ALL; n = 157) or acute myelogenous leukemia (AML; n = 95) diagnosed before 1 year of age who received a single-unit UCBT after myeloablative conditioning between 1996 and 2012 in European Society for Blood and Marrow Transplantation centers. Median age at UCBT was 1.1 years, and median follow-up was 42 months. Most patients (57%) received a graft with 1 HLA disparity and were transplanted in first complete remission (CR; 55%). Cumulative incidence function (CIF) of day 100 acute GVHD (grades II to IV) was 40% ± 3% and of 4-year chronic GVHD was 13% ± 2%. CIF of 1-year transplant-related mortality was 23% ± 3% and of 4-year relapse was 27% ± 3%. Leukemia-free-survival (LFS) at 4 years was 50% ± 3%; it was 40% and 66% for those transplanted for ALL and AML, respectively (P = .001). LFS was better for patients transplanted in first CR, regardless of diagnosis. In multivariate model, diagnosis of ALL (P = .001), advanced disease status at UCBT (<.001), age at diagnosis younger than 3 months (P = .012), and date of transplant before 2004 were independently associated with worse LFS. UCBT is a suitable option for patients diagnosed with infant acute leukemia who achieve CR. In this cohort, patients with AML had better survival than those with ALL

    New lithostratigraphy for the Cantabrian Mountains: A common tectono-stratigraphic evolution for the onset of the Alpine cycle in the W Pyrenean realm, N Spain

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    The Pyrenean-Cantabrian Orogen arose through the collision of the Iberian and Eurasian plates, mostly in Cenozoic times. This orogen comprises two main mountain ranges, the Pyrenees to the east, and the Cantabrian Mountains to the west. To date, the early Alpine tectono-sedimentary phases preserved in the Cantabrian Mountains, of Permian and Triassic age, have been considered independently from the same phases in neighbouring basins of SW Europe, and even from the eastern part of the same orogeny (the Pyrenean orogeny). In consequence, the beginning of the Alpine cycle in the Cantabrian Mountains has been interpreted within a specific geodynamic context, far from the general evolutionary phases of the western Peri-Tethys basins. Through detailed field work, including geological mapping, sedimentology, lithostratigraphy and petrology of volcanic rocks, and new palaeontological data, here we define several new lithostratigraphical formations and five new tectono-sedimentary cycles (TS I-V) for the initial phases of evolution of the Mesozoic Basque-Cantabrian Basin, interrupted by periods of tectonic stability. To complete this information, we include data from an onshore borehole (Villabona Mine) and two offshore boreholes constrained by 2D reflection seismic profiles acquired in the North Iberian continental platform. The main tectono-sedimentary cycles, related to the deposition of five major identified lithostratigraphic units, can be described as follows: TS I (late Gzelian-early Asselian), relating to the late Variscan deformation and preserved in a single outcrop in all the Cantabrian Mountains (San Tirso Formation). This formation is constituted by medium-distal alluvial fan deposits in which humid intervals predominate, forming some thin coal beds. TS II (Asselian-Sakmarian), a post-Variscan extensional phase with associated calc-alkaline magmatism, represented by profuse volcanic and volcanosedimentary intercalations in the early Permian sedimentary basins (Acebal Formation) and small plutons in surrounding areas. TS III (Kungurian), or reactivation of the post-Variscan extension leading to alluvial and lacustrine carbonate sedimentation in arid climate conditions, which do not change during the rest of the Permian and Triassic periods (Sotres Formation). A generalized karstification in the basin represents the end of Permian deposition, followed by an interruption in sedimentation longer than 30 Myr. The Permian tectono-sedimentary cycles (TS II and TS III) are contemporary with Variscan belt collapse and the basins are controlled by extensional reactivation of NE-SW and E-W Variscan structures, and NW-SE late Variscan structures. TS IV (late Anisian–middle Carnian), renewed sedimentation in more extensive basins, precursors of the great Mesozoic Basque-Cantabrian Basin. This cycle is represented by fluvial deposits (Cicera Formation, or Buntsandstein facies), which are interrupted by the first Mesozoic marine ingression (Rueda Formation, or Muschelkalk facies). TS V (Norian-Rhaetian), or shallow marine carbonate deposits (Transición Formation) related to increasingly compartmentalized sub-basins, controlled by normal faults. This final TS is broadly connected with different basins of the western Peri-Tethys domain. The identification of units TS I-V in the Cantabrian Mountains along with the volcanic character of TS II, all indicate the development of a common post-Variscan to early Alpine tectono-sedimentary evolution for the whole Pyrenean-Cantabrian realm

    Taxing the Informal Economy: The Current State of Knowledge and Agendas for Future Research

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    This paper reviews the literature on taxation of the informal economy, taking stock of key debates and drawing attention to recent innovations. Conventionally, the debate on whether to tax has frequently focused on the limited revenue potential, high cost of collection, and potentially adverse impact on small firms. Recent arguments have increasingly emphasised the more indirect benefits of informal taxation in relation to economic growth, broader tax compliance, and governance. More research is needed, we argue, into the relevant costs and benefits for all, including quasi-voluntary compliance, political and administrative incentives for reform, and citizen-state bargaining over taxation
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