7,052 research outputs found

    The MSSM from Scherk-Schwarz Supersymmetry Breaking

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    We present a five-dimensional model compactified on an interval where supersymmetry is broken by the Scherk-Schwarz mechanism. The gauge sector propagates in the bulk, two Higgs hypermultiplets are quasilocalized, and quark and lepton multiplets localized, in one of the boundaries. The effective four-dimensional theory is the MSSM with very heavy gauginos, heavy squarks and light sleptons and Higgsinos. The soft tree-level squared masses of the Higgs sector can be negative and they can (partially) cancel the positive one-loop contributions from the gauge sector. Electroweak symmetry breaking can then comfortably be triggered by two-loop radiative corrections from the top-stop sector. The fine tuning required to obtain the electroweak scale is found to be much smaller than in the MSSM, with essentially no fine-tuning for few TeV gaugino masses. All bounds from direct Higgs searches at LEP and from electroweak precision observables can be satisfied. The lightest supersymmetric particle is a (Higgsino-like) neutralino that can accomodate the abundance of Dark Matter consistently with recent WMAP observations.Comment: 23 pages, 3 figure

    Orbital and physical properties of planets and their hosts: new insights on planet formation and evolution

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    We explore the relations between physical and orbital properties of planets and properties of their host stars to identify the main observable signatures of the formation and evolution processes of planetary systems. We use a large sample of FGK dwarf planet hosts with stellar parameters derived in a homogeneous way from the SWEET-Cat database to study the relation between stellar metallicity and position of planets in the period-mass diagram. In the second part we use all the RV-detected planets orbiting FGK stars to explore the role of planet-disk and planet-planet interaction on the evolution of orbital properties of planets with masses above 1MJup. We show that planets orbiting metal-poor stars have longer periods than those in metal-rich systems. This trend is valid for masses at least from 10MEarth to 4MJup. Earth-like planets orbiting metal-rich stars always show shorter periods (fewer than 20 days) than those orbiting metal-poor stars. We also found statistically significant evidence that very high mass giants have on average more eccentric orbits than giant planets with lower mass.Finally, we show that the eccentricity of planets with masses higher than 4MJup tends to be lower for planets with shorter periods. Our results suggest that the planets in the P-MP diagram are evolving differently because of a mechanism that operates over a wide range of planetary masses. This mechanism is stronger or weaker depending on the metallicity of the respective system. One possibility is that planets in metal-poor disks form farther out from their central star and/or they form later and do not have time to migrate as far as the planets in metal-rich systems. The trends and dependencies obtained for very high mass planetary systems suggest that planet-disk interaction is a very important and orbit-shaping mechanism for planets in the high-mass domain. Shortened.Comment: 8 pages, 4 figures and 1 table. Accepted for publication in A&

    Percolative phase transition on ferromagnetic insulator manganites: uncorrelated to correlated polaron clusters

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    In this work, we report an atomic scale study on the ferromagnetic insulator manganite LaMnO3.12_{3.12} using γγ\gamma-\gamma PAC spectroscopy. Data analysis reveals a nanoscopic transition from an undistorted to a Jahn-Teller-distorted local environment upon cooling. The percolation thresholds of the two local environments enclose a macroscopic structural transition (Rhombohedric-Orthorhombic). Two distinct regimes of JT-distortions were found: a high temperature regime where uncorrelated polaron clusters with severe distortions of the Mn3+^{3+}O6_{6} octahedra survive up to T800KT \approx 800 K and a low temperature regime where correlated regions have a weaker JT-distorted symmetry.Comment: 4 pages, 4 Figures, submitted to PRL, new version with more data, text reformulate

    Composição proximal em filés, rendimento de carcaça e de cortes de jundiá (rhamdia quelen) alimentados com rações contendo diferentes óleos vegetais.

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    Este trabalho teve por objetivos avaliar a influência de óleos vegetais no desenvolvimento corporal de jundiá (Rhamdia quelen, Heptapteridae) e sua relação com o rendimento de carcaça, partes comestíveis e composição química do filé. Testaram-se seis rações com 32% de proteína bruta, sendo avaliados óleos de arroz, canola ou soja com 5 e 10% de inclusão durante 90 dias. Foram utilizados 180 peixes (peso inicial=71±0,81g) distribuídos ao acaso em 18 caixas de 280L (10 peixes/caixa) em um sistema de recirculação de água, com temperatura controlada (25,9±0,9ºC). Não houve diferenças para os parâmetros produtivos entre os tratamentos testados ao final do experimento (P<0,05). Os peixes alimentados com maiores níveis de óleo nas dietas depositaram maior porcentagem de gordura no filé. Conclui-se que os óleos de canola, arroz e soja utilizados como alternativas em dietas na recria de jundiá proporcionam bom rendimento de carcaça e de partes comestíveis. E, as rações contendo óleo de canola possibilitam menor deposição de gordura no filé de juvenis de jundiá em nível de 5%

    Produção de mudas micropropagadas de abacaxizeiro ornamental em diferentes substratos na presença e ausência de fertilizante.

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    Projeto Gavião: impactos (meio período) do desenvolvimento rural - 1998/2001.

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    Phytosociological surveys: tools for weed science?

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    Made available in DSpace on 2014-03-07T23:23:12Z (GMT). No. of bitstreams: 1 germaniplanta.pdf: 1437590 bytes, checksum: 2518af349217cec531443f69ffd935f2 (MD5) Previous issue date: 2013-11-08201

    The personal belief in a just world and domain-specific beliefs about justice at school and in the family: A longitudinal study with adolescents

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    This article investigates the relationship between the personal belief in a just world (BJW) and domain-specific beliefs about justice and examines how justice cognitions impact on adolescents' development, particularly on their achievement at school and their subjective well-being. A longitudinal questionnaire study with German adolescents aged 14-19 years was conducted over a period of five to eight months. The pattern of results revealed that evaluations of the school climate and of the family climate as being just were two distinct phenomena, both of which impacted on the personal BJW, which in turn affected the domain-specific beliefs about justice. However, the domain-specific beliefs about justice did not impact on each other directly. Moreover, an evaluation of the family climate (but not of the school climate) as being just reduced depressive symptoms, whereas depressive symptoms did not weaken the evaluation of one's family as being just. The evaluation of the school climate as being just improved the grades received in the next school report, whereas the grades received did not affect the justice evaluation of the school climate. Finally, all relationships persisted when controlling for age and gender. In sum, the pattern of findings supports the notion that justice cognitions impact on development during adolescence
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