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

Measurement of the ttbar Production Cross Section in ppbar collisions at sqrt s = 1.96 TeV in the All Hadronic Decay Mode

We report a measurement of the ttbar production cross section using the CDF-II detector at the Fermilab Tevatron. The analysis is performed using 311 pb-1 of ppbar collisions at sqrt(s)=1.96 TeV. The data consist of events selected with six or more hadronic jets with additional kinematic requirements. At least one of these jets must be identified as a b-quark jet by the reconstruction of a secondary vertex. The cross section is measured to be sigma(tbart)=7.5+-2.1(stat.)+3.3-2.2(syst.)+0.5-0.4(lumi.) pb, which is consistent with the standard model prediction.Comment: By CDF collaboratio

Search for chargino-neutralino production in ppbar collisions at sqrt(s) = 1.96 TeV

We present the results of a search for associated production of the chargino and neutralino supersymmetric particles using up to 1.1 fb-1 of integrated luminosity collected by the CDF II experiment at the Tevatron ppbar collider at a center-of-mass energy of 1.96 TeV. The search is conducted by analyzing events with a large transverse momentum imbalance and either three charged leptons or two charged leptons of the same electric charge. The numbers of observed events are found to be consistent with standard model expectations. Upper limits on the production cross section are derived in different theoretical models. In one of these models a lower limit on the mass of the chargino is set at 129 GeV/c^2 at the 95% confidence level.Comment: To be submitted to Phys.Rev.Let

An invasive species induces rapid adaptive change in a native predator: cane toads and black snakes in Australia

Rapid environmental change due to human activities has increased rates of extinction, but some species may be able to adapt rapidly enough to deal with such changes. Our studies of feeding behaviour and physiological resistance to toxins reveal surprisingly rapid adaptive responses in Australian black snakes (Pseudechis porphyriacus) following the invasion of a lethally toxic prey item, the cane toad (Bufo marinus). Snakes from toad-exposed localities showed increased resistance to toad toxin and a decreased preference for toads as prey. Separate laboratory experiments suggest that these changes are not attributable to learning (we were unable to teach naive snakes to avoid toxic prey) or to acquired resistance (repeated sub-lethal doses did not enhance resistance). These results strongly suggest that black snake behaviour and physiology have evolved in response to the presence of toads, and have done so rapidly. Toads were brought to Australia in 1935, so these evolved responses have occurred in fewer than 23 snake generations

Digitization and transmission of human experience

Transmission of human experience is essential for many purposes. It has two aspects: content and social relations. Digital technologies can solve some of the classic issues around the capture and transmission of human experience. Using these new technical affordances as a basis, this article presents a framework to capture and describe human activity and experience based on video and cooperative explicitation of activity trajectories with the subject, using a transition model inspired by the formalism of dynamical systems. The article also introduces this special issue, 'Digitize and Transfer', and gives an overview of its contents

Efeito de diferentes níveis de sódio e fósforo sobre o desempenho e a qualidade da casca dos ovos de poedeiras comerciais Effect of different levels of sodium and phosphorus on performance and eggshell quality of laying hens

Conduziu-se um experimento com o objetivo de verificar o efeito de diferentes níveis de sódio e fósforo (P) sobre o desempenho e a qualidade da casca dos ovos e de determinados constituintes sangüíneos, em 144 galinhas Hy-Line W36, com 60 semanas de idade, distribuídas em 36 unidades experimentais com quatro aves cada. O delineamento utilizado foi o de blocos ao acaso em arranjo fatorial (3 x 3), níveis de sódio (0,16; 0,20; e 0,24%) e níveis de fósforo total (0,35; 0,45; e 0,55%), totalizando nove tratamentos, dois blocos com duas repetições em cada bloco. As rações experimentais foram isoprotéicas (16,0% de PB), isocalóricas (2800 kcal de EM/kg) e isocálcicas (4,0% de Ca). Consumo de ração, produção e massa de ovos, conversão alimentar, porcentagem e espessura da casca e densidade aparente dos ovos não foram alteradas pelos níveis de sódio. Entretanto, quando as galinhas foram alimentadas com dietas contendo 0,35% de P total, verificou-se comprometimento da produção e massa de ovos e conversão alimentar, sem alteração das características de qualidade da casca. Houve interação entre os fatores para o peso dos ovos. Baixos níveis de P total não foram efetivos em melhorar a qualidade da casca dos ovos, mas prejudicaram o desempenho das galinhas.<br>An experiment was carried out to verify the effect of different levels of sodium and phosphorus (P) on the performance, eggshell quality and on some blood constituents of 144 laying hens Hy-Line W36, aged 60 weeks, allotted to 36 experimental units with four hens each. A randomized experimental block design was used in a factorial arrangement (3 x 3), sodium levels (.16, .20 and .24%) and phosphorus levels (.35, .45 and .55%), totalizing nine treatments, two blocks with two replicates each. The experimental diets were isoproteic (16.0% CP), isoenergetic (2,800 kcal ME/kg) and isocalcium (4.0% Ca). Feed intake, egg production, egg mass, feed:gain ratio, shell percentage, shell thickness and egg specific gravity were not affected by sodium levels. However, when the hens were fed diets containing .35% total P, there was impairment of the egg production, egg mass and feed:gain ratio, without modification of the eggshell quality characteristics. There was interaction between the factors for egg weight. Low phosphorus levels were not effective to improve the eggshell quality, but impaired hens performance