55 research outputs found

    Absorbing-state phase transitions in fixed-energy sandpiles

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    We study sandpile models as closed systems, with conserved energy density ζ\zeta playing the role of an external parameter. The critical energy density, ζc\zeta_c, marks a nonequilibrium phase transition between active and absorbing states. Several fixed-energy sandpiles are studied in extensive simulations of stationary and transient properties, as well as the dynamics of roughening in an interface-height representation. Our primary goal is to identify the universality classes of such models, in hopes of assessing the validity of two recently proposed approaches to sandpiles: a phenomenological continuum Langevin description with absorbing states, and a mapping to driven interface dynamics in random media. Our results strongly suggest that there are at least three distinct universality classes for sandpiles.Comment: 41 pages, 23 figure

    Quantum Physics Exploring Gravity in the Outer Solar System: The Sagas Project

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    We summarise the scientific and technological aspects of the SAGAS (Search for Anomalous Gravitation using Atomic Sensors) project, submitted to ESA in June 2007 in response to the Cosmic Vision 2015-2025 call for proposals. The proposed mission aims at flying highly sensitive atomic sensors (optical clock, cold atom accelerometer, optical link) on a Solar System escape trajectory in the 2020 to 2030 time-frame. SAGAS has numerous science objectives in fundamental physics and Solar System science, for example numerous tests of general relativity and the exploration of the Kuiper belt. The combination of highly sensitive atomic sensors and of the laser link well adapted for large distances will allow measurements with unprecedented accuracy and on scales never reached before. We present the proposed mission in some detail, with particular emphasis on the science goals and associated measurements.Comment: 39 pages. Submitted in abridged version to Experimental Astronom

    ParĂąmetros populacionais da raça ovina Santa InĂȘs no Brasil

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    O objetivo deste trabalho foi avaliar a estrutura populacional de ovinos da raça Santa InĂȘs criados no Brasil. Foram utilizados dados de pedigree de 13.216 animais, pertencentes a 53 rebanhos de oito estados brasileiros, nascidos no perĂ­odo de 1976 a 2010. O programa Endog foi utilizado para anĂĄlise do pedigree e estimação dos parĂąmetros populacionais. Do total de animais estudados, 80,86% apresentaram pedigree na primeira ascendĂȘncia, 73,78% na segunda e 67,75% na terceira. O nĂșmero mĂĄximo de geraçÔes conhecidas foi de 19, e a mĂ©dia de geraçÔes equivalentes foi de 4,67. A mĂ©dia do intervalo de geraçÔes foi de 3,22±1,77 anos. O tamanho efetivo da população apresentou mĂ©dia de 172,5 animais. O nĂșmero de animais fundadores foi 829, mas o nĂșmero efetivo de fundadores foi apenas 50. Os 17 principais ancestrais explicaram 50% da variabilidade genĂ©tica total. O coeficiente mĂ©dio de relação foi de 3,87% e o de endogamia, de 6,92%. Apesar do satisfatĂłrio coeficiente mĂ©dio de endogamia nas Ășltimas geraçÔes, este coeficiente requer monitoramento por sua proximidade do limite recomendĂĄvel. O fluxo de genes entre os rebanhos Ă© o principal fator para o aumento do tamanho efetivo e a manutenção da variabilidade genĂ©tica da raça Santa InĂȘs

    Caracterização do gene vip3A e toxicidade da proteína Vip3Aa50 à lagarta-do-cartucho e à lagarta-da-soja

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    O objetivo deste trabalho foi caracterizar o gene vip3A de Bacillus thuringiensis e verificar a toxicidade da proteĂ­na Vip3Aa50 a larvas da lagarta-do-cartucho (Spodoptera frugiperda) e da lagarta-da-soja (Anticarsia gemmatalis). O gene vip3A foi amplificado por PCR, com iniciadores especĂ­ficos, e gerou um fragmento de 2.370 pb. Esse fragmento foi clonado em vetor pGEM-T Easy e, em seguida, sequenciado, subclonado em vetor de expressĂŁo pET-28a (+) e inserido em cĂ©lulas de Escherichia coli BL21 (DE3). A expressĂŁo da proteĂ­na Vip3Aa50 foi induzida por isopropil-ÎČ-D-1-tiogalactopiranosĂ­deo (IPTG), visualizada em SDS-PAGE e detectada por "Western blot". Os ensaios de toxicidade revelaram alta atividade da proteĂ­na Vip3Aa50 contra as larvas neonatas da lagarta-da-soja e da lagarta-do-cartucho, com CL50 de 20,3 e 79,6 ng cm-2, respectivamente. O gene vip3Aa50 Ă© um novo gene da classe vip3A

    Combination of searches for Higgs boson pairs in pp collisions at \sqrts = 13 TeV with the ATLAS detector

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    This letter presents a combination of searches for Higgs boson pair production using up to 36.1 fb(-1) of proton-proton collision data at a centre-of-mass energy root s = 13 TeV recorded with the ATLAS detector at the LHC. The combination is performed using six analyses searching for Higgs boson pairs decaying into the b (b) over barb (b) over bar, b (b) over barW(+)W(-), b (b) over bar tau(+)tau(-), W+W-W+W-, b (b) over bar gamma gamma and W+W-gamma gamma final states. Results are presented for non-resonant and resonant Higgs boson pair production modes. No statistically significant excess in data above the Standard Model predictions is found. The combined observed (expected) limit at 95% confidence level on the non-resonant Higgs boson pair production cross-section is 6.9 (10) times the predicted Standard Model cross-section. Limits are also set on the ratio (kappa(lambda)) of the Higgs boson self-coupling to its Standard Model value. This ratio is constrained at 95% confidence level in observation (expectation) to -5.0 &lt; kappa(lambda) &lt; 12.0 (-5.8 &lt; kappa(lambda) &lt; 12.0). In addition, limits are set on the production of narrow scalar resonances and spin-2 Kaluza-Klein Randall-Sundrum gravitons. Exclusion regions are also provided in the parameter space of the habemus Minimal Supersymmetric Standard Model and the Electroweak Singlet Model. For complete list of authors see http://dx.doi.org/10.1016/j.physletb.2019.135103</p

    Searches for lepton-flavour-violating decays of the Higgs boson in s=13\sqrt{s}=13 TeV pp\mathit{pp} collisions with the ATLAS detector

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    This Letter presents direct searches for lepton flavour violation in Higgs boson decays, H → eτ and H → Ότ , performed with the ATLAS detector at the LHC. The searches are based on a data sample of proton–proton collisions at a centre-of-mass energy √s = 13 TeV, corresponding to an integrated luminosity of 36.1 fb−1. No significant excess is observed above the expected background from Standard Model processes. The observed (median expected) 95% confidence-level upper limits on the leptonflavour-violating branching ratios are 0.47% (0.34+0.13−0.10%) and 0.28% (0.37+0.14−0.10%) for H → eτ and H → Ότ , respectively.publishedVersio
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