10,551 research outputs found

    Atomically thin dilute magnetism in Co-doped phosphorene

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    Two-dimensional dilute magnetic semiconductors can provide fundamental insights in the very nature of magnetic orders and their manipulation through electron and hole doping. Despite the fundamental physics, due to the large charge density control capability in these materials, they can be extremely important in spintronics applications such as spin valve and spin-based transistors. In this article, we studied a two-dimensional dilute magnetic semiconductors consisting of phosphorene monolayer doped with cobalt atoms in substitutional and interstitial defects. We show that these defects can be stabilized and are electrically active. Furthermore, by including holes or electrons by a potential gate, the exchange interaction and magnetic order can be engineered, and may even induce a ferromagnetic-to-antiferromagnetic phase transition in p-doped phosphorene.Comment: 7 pages, 4 colorful figure

    From ‘creative cities’ to ‘urban creativity’? Space, creativity and governance in the contemporary city

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    DINÂMIA, Dezembro de 2009This paper derives from a broader research program studying the forms of governance associated with creative dynamics in cities (the “Creatcity” project) and draws on the first empirical results generated by the study following analysis of a set of exploratory interviews involving actors central to thinking and acting on the contemporary city (political decision makers, official structures and civil society) in the three metropolitan areas selected for the project: Lisbon (Portugal), São Paulo (Brazil) and Barcelona (Spain). Analysis of the responses sought to identify the different perspectives on the concepts of urban creativity and creative city and the relationship between creativity, vitality and competitivity within urban contexts while seeking to understand interviewee perspectives on the structural conditions necessary for the development of creativity in the city in terms of spatial/geographic configurations and the associated cultural ambiances and economic activities. In parallel, we aim to debate the means of fostering and supporting creativity in urban environments and discuss just which strategic policies and governance processes best achieve this.FC

    Dileptons from the nonequilibrium Quark-Gluon Plasma

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    According to the dynamical quasiparticle model (DQPM) -- matched to reproduce lattice QCD results in thermodynamic limit, -- the constituents of the strongly interacting quark-gluon plasma (sQGP) are massive and off-shell quasi-particles (quarks and gluons) with broad spectral functions. In order to address the electromagnetic radiation of the sQGP, we derive off-shell cross sections of qqˉγq\bar q\to\gamma^*, qqˉγ+gq\bar q\to\gamma^*+g and qgγqqg\to\gamma^*q(qˉgγqˉ\bar q g\to\gamma^* \bar q) reactions taking into account the effective propagators for quarks and gluons from the DQPM. Dilepton production in In+In collisions at 158 AGeV is studied by implementing these processes into the parton-hadron-string dynamics (PHSD) transport approach. The microscopic PHSD transport approach describes the full evolution of the heavy-ion collision: from the dynamics of quasi-particles in the sQGP phase (when the local energy density is above 1\sim 1 GeV/fm3^3) through hadronization and to the following hadron interactions and off-shell propagation after the hadronization. A comparison to the data of the NA60 Collaboration shows that the low mass dilepton spectra are well described by including a collisional broadening of vector mesons, while the spectra in the intermediate mass range are dominated by off-shell quark-antiquark annihilation, quark Bremsstrahlung and gluon-Compton scattering in the nonperturbative QGP. In particular, the observed softening of the mTm_T spectra at intermediate masses (1 GeV M\le M \le 3 GeV) is approximately reproduced.Comment: 8 pages, 8 figures, to be published in the Proceedings of the 26th Winter Workshop on `Nuclear Dynamics', Ochto Rios, Jamaica, 2-9 January, 201

    Relação treinador-atleta no atletismo: da teoria à prática

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    Neste trabalho propomo-nos a analisar a relação treinador-atleta no contexto da modalidade desportiva do atletismo. Faremos uma análise teórica e uma análise prática das implicações existentes para um melhor exercício da liderança por parte dos treinadores. Do ponto de vista teórico, pedimos, desde já, desculpa ao leitor por não efetuarmos uma análise dos modelos teóricos existentes a nível internacional e por optarmos por nos cingirmos apenas a um modelo centrado no estudo da eficácia dos treinadores. Esta opção deve-se, sobretudo, à significativa quantidade de informação a expor sobre o modelo em causa, não restando muito mais espaço para nos dedicarmos a outras abordagens teóricas. Seja como for, estas estão amplamente difundidas na literatura e o leitor poderá facilmente inteirar-se destes contributos (ver, por exemplo, Bass & Riggio, 2006; Chelladurai, 2012; Horn, 2008; Jowett et al., 2005; Smith & Smoll, 2007). Por outro lado, ao cingirmo-nos a um único modelo podemos debater com maior pormenor as implicações específicas para a ação dos treinadores. Com isto, conseguimos propor ao leitor interessado neste tema, um trabalho mais uniforme e congruente acerca da compreensão da relação complexa estabelecida entre treinador e atletas.info:eu-repo/semantics/publishedVersio

    Co‐existing monophasic teratoma and uterine adenocarcinoma in a female dog

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    Ovarian teratomas are occasionally reported in dogs; the rarest type is the monophasic teratoma,composed of tissues originating from only one germ layer. Canine endometrial adenocarcinomas are also rare in dogs and mainly affect geriatric females. This report describes case of co-existing ovarian teratoma and uterine adenocarcinoma in a 10-year old nulliparous female Boxer presented with lethargy, anorexia and purulent vaginal discharge. Abdominal ultrasonography evidenced pyometra and a mass in the left ovary. This was composed of a uniform whitish tissue with multiple cystic structures. The histology revealed an atrophy of the ovarian parenchyma, compressed by a proliferation of well-differentiated nervous tissue staining positively to vimentin, S100 and neuronal specific enolase (NSE), and negatively to keratin and inhibin. The left uterine horn, whose diameter was markedly increased, showed foci of endometrial cellular atypia, evident nucleoli and mitoses, at light microscopy. To our best knowledge, this is the first report of a coexisting ovarian monophasic teratoma and endometrial adenocarcinoma, two rare reproductive neoplasia in dogs

    A Receiver System for the TileCal Muon Signals

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    During the detector commissioning period, the TileCal muon signals have been used to trigger cosmic rays, as this signal, currently, is not being used by ATLAS level 1 muon trigger. Studies showed that the signal-to-noise ratio at the level 1 muon trigger is increased if both muon signals seeing the same D cell are summed. Thus, a system has been developed to receive TileCal muon signals and to aid ATLAS level 1 muon trigger. This article describes the receiver system and its main features, as well as circuit simulations

    Evolutionary Constraints in the b-Globin Cluster: The Signature of Purifying Selection at the d-Globin (HBD) Locus and Its Role in Developmental Gene Regulation

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    Human hemoglobins, the oxygen carriers in the blood, are composed by two α-like and two β-like globin monomers. The β-globin gene cluster located at 11p15.5 comprises one pseudogene and five genes whose expression undergoes two critical switches: the embryonic-to-fetal and fetal-to-adult transition. HBD encodes the δ-globin chain of the minor adult hemoglobin (HbA2), which is assumed to be physiologically irrelevant. Paradoxically, reduced diversity levels have been reported for this gene. In this study, we sought a detailed portrait of the genetic variation within the β-globin cluster in a large human population panel from different geographic backgrounds. We resequenced the coding and noncoding regions of the two adult β-globin genes (HBD and HBB) in European and African populations, and analyzed the data from the β-globin cluster (HBE, HBG2, HBG1, HBBP1, HBD, and HBB) in 1,092 individuals representing 14 populations sequenced as part of the 1000 Genomes Project. Additionally, we assessed the diversity levels in nonhuman primates using chimpanzee sequence data provided by the PanMap Project. Comprehensive analyses, based on classic neutrality tests, empirical and haplotype-based studies, revealed that HBD and its neighbor pseudogene HBBP1 have mainly evolved under purifying selection, suggesting that their roles are essential and nonredundant. Moreover, in the light of recent studies on the chromatin conformation of the β-globin cluster, we present evidence sustaining that the strong functional constraints underlying the decreased contemporary diversity at these two regions were not driven by protein function but instead are likely due to a regulatory role in ontogenic switches of gene expression

    Exciton binding energies and luminescence of phosphorene under pressure

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    The optical response of phosphorene can be gradually changed by application of moderate uniaxial compression, as the material undergoes the transition into an indirect gap semiconductor and eventually into a semimetal. Strain tunes not only the gap between the valence band and conduction band local extrema, but also the effective masses, and in consequence, the exciton anisotropy and binding strength. In this article, we consider from a theoretical point of view how the exciton stability and the resulting luminescence energy evolves under uniaxial strain. We find that the exciton binding energy can be as large as 0.87 eV in vacuum for 5% transverse strain, placing it amongst the highest for 2D materials. Further, the large shift of the luminescence peak and its linear dependence on strain suggest that it can be used to probe directly the strain state of single-layers.Comment: 6 pages, 5 figure
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