Temperatura e pré-condicionamento de sementes de soja para o teste de tetrazólio

The objective of this study was to determine the possibility of reducing the preconditioning period (imbibition time) before the staining process in the tetrazolium test for soybean seeds. Seeds of the cultivars OCEPAR 4-Iguacu and BR-4 with different levels of quality, were submitted to four periods of imbibition (4, 6, 8 and 10 h) under two temperatures (35°C and 42 °C). The standard procedure used for soybean seeds in the tetrazolium test (16h/25°C) was used as the control. It was concluded that the temperature used during the precondidioning process of the seeds affects the precision of the test: preconditioning at 42°C for 8 to 10 h, and eventually for 6h, results in adequate staining patterns of the seed structures. This allows the identification of the typical patterns that result from seed deterioration (field weathering), sting bug damage and mechanical injury.Com o objetivo de encontrar uma alternativa metodológica para a redução do período de condicionamento (tempo de embebição) que antecede o processo de coloração de sementes para a realização do teste de tetrazólio, foram estudados quatro períodos de embebição (4h, 6h, 8h e 10h) e duas temperaturas (35° C e 42 °C) tendo como testemunha o procedimento padrão de 16 horas de embebição a 25°C. Utilizaram-se lotes de sementes de soja dos cultivares OCEPAR 4-Iguaçu e BR-4. A análise dos dados e a interpretação dos resultados mostraram que a temperatura empregada para o pré-condicionamento das amostras é fundamental no mecanismo de coloração das sementes através do teste de tetrazólio. Assim, a embebição de sementes de soja à temperatura de 42°C durante oito a dez horas e, possivelmente durante seis horas, permite o posterior desenvolvimento de coloração suficientemente nítida para o exame adequado das áreas vitais das sementes e a identificação de sintomas de deterioração por "umidade", danos de percevejos e ocorrência de injúrias mecânicas. De maneira geral, sementes dos cultivares em estudo apresentaram bom aspecto de coloração no teste de tetrazólio, quando o grau de umidade das sementes atingiu, no mínimo, 32 a 33%

The signed loop approach to the Ising model: foundations and critical point

The signed loop method is a beautiful way to rigorously study the two-dimensional Ising model with no external field. In this paper, we explore the foundations of the method, including details that have so far been neglected or overlooked in the literature. We demonstrate how the method can be applied to the Ising model on the square lattice to derive explicit formal expressions for the free energy density and two-point functions in terms of sums over loops, valid all the way up to the self-dual point. As a corollary, it follows that the self-dual point is critical both for the behaviour of the free energy density, and for the decay of the two-point functions.Comment: 38 pages, 7 figures, with an improved Introduction. The final publication is available at link.springer.co

Global Search for New Physics with 2.0/fb at CDF

Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication

Observation of Orbitally Excited B_s Mesons

We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV

The elliptic, $v_2$, triangular, $v_3$, and quadrangular, $v_4$, azimuthal anisotropic flow coefficients are measured for unidentified charged particles, pions and (anti-)protons in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV with the ALICE detector at the Large Hadron Collider. Results obtained with the event plane and four-particle cumulant methods are reported for the pseudo-rapidity range $|\eta|<0.8$ at different collision centralities and as a function of transverse momentum, $p_{\rm T}$, out to $p_{\rm T}=20$ GeV/$c$. The observed non-zero elliptic and triangular flow depends only weakly on transverse momentum for $p_{\rm T}>8$ GeV/$c$. The small $p_{\rm T}$ dependence of the difference between elliptic flow results obtained from the event plane and four-particle cumulant methods suggests a common origin of flow fluctuations up to $p_{\rm T}=8$ GeV/$c$. The magnitude of the (anti-)proton elliptic and triangular flow is larger than that of pions out to at least $p_{\rm T}=8$ GeV/$c$ indicating that the particle type dependence persists out to high $p_{\rm T}$.Comment: 16 pages, 5 captioned figures, authors from page 11, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186