Heating up the cold bounce

Self-dual string cosmological models provide an effective example of bouncing solutions where a phase of accelerated contraction smoothly evolves into an epoch of decelerated Friedmann--Robertson--Walker expansion dominated by the dilaton. While the transition to the expanding regime occurs at sub-Planckian curvature scales, the Universe emerging after the bounce is cold, with sharply growing gauge coupling. However, since massless gauge bosons (as well as other massless fields) are super-adiabatically amplified, the energy density of the maximally amplified modes re-entering the horizon after the bounce can efficiently heat the Universe. As a consequence the gauge coupling reaches a constant value, which can still be perturbative.Comment: 28 pages, 13 figure

Electromagnetic Origin of the CMB Anisotropy in String Cosmology

In the inflationary scenarios suggested by string theory, the vacuum fluctuations of the electromagnetic field can be amplified by the time-evolution of the dilaton background, and can grow large enough to explain both the origin of the cosmic magnetic fields and of the observed CMB anisotropy. The normalization of the perturbation spectrum is fixed, and implies a relation between the perturbation amplitude at the COBE scale and the spectral index $n$. Working within a generic two-parameter family of backgrounds, a large scale anisotropy $\Delta T/T\simeq 10^{-5}$ is found to correspond to a spectral index in the range $n\simeq 1.11 - 1.17$.Comment: 11 pages, LATE

In vitro efficacy of alphacypermethrin on the buffalo louse Haematopinus tuberculatus (Burmeister, 1839).

In Italy buffalo farms adopted intensive breeding techniques, however the high density of animals in intensive breeding favours the diffusion of ectoparasites, such as louse. The aim of this study was to determine the in vitro efficacy of the insecticide alphacypermethrin (ACYP) against the buffalo louse, Haematopinus tuberculatus. The study was performed by using louse collected from animals in a commercial buffalo farm located in the Campania region of Southern Italy. Lice (adults and nymphs) were collected from highly infested buffaloes. The ACYP was diluted with physiological solution to different concentrations: 1.5%, 0.75%, 0.37%. A volume of 600 μl of the diluted sample was spread evenly over a filter paper held in the lower half of Petri dish. Ten adult lice and ten nymphs were placed on the top of each filter paper disc. The control groups were treated with physiological solution. Seven replicates were used for each concentration. The louse vitality was assessed at different time intervals: 1, 2, 4, 8, 10, 15, 20, 30, 40, 50, 60 minutes, after every 10 min until 240 min or at the louse death. After 240 min the louse vitality was examined each 60 min until 540 min. In vitro bioassays revealed that the lousicidal efficacy of ACYP improved as the concentration and the exposure time increased. The results of this in vitro study confirm that ACYP at 1.5% concentration can also be used in buffalo for the control of lice, as already in use in cattle. Further field trials will need to be conducted to confirm the safety, the dosage and the in vivo parasitological efficacy of this drug on buffaloes

Peak and end point of the relic graviton background in string cosmology

Using general arguments we determine the allowed region for the end point frequency and the peak energy density of the stochastic background of gravity waves expected in string cosmology. We provide an accurate estimate of the minimal experimental sensitivity required to detect a signal in the Hz to GHz range.Comment: 11 pages, LATEX, one figure included using eps. A complete collection of papers and references on the pre-big-bang scenario in string cosmology is available at http://www.to.infn.it/teorici/gasperini

Coleção ativa de germoplasmas de Coffea arabica L.: situação atual, caracterização e perspectivas para Rondônia.

Em Rondônia, cultivares da espécie arábica (Coffea arabica L.; Rubiaceae) são plantadas em apenas 5 % da área total (160 mil hectares) do parque cafeeiro estadual, dentre outros motivos, por causa da C. arabica apresentar restrita variabilidade genética para os caracteres de importância adaptativa, econômica e de defensividade nas condições ambientais da Amazônia Ocidental. As principais cultivares comerciais brasileiras de C. arabica são muito aparentadas entre si por serem exclusivamente descendentes das populações-base Bourbon e Typica. De 1978 a 2000, foram introduzidos e avaliados, aproximadamente, 120 acessos de C. arabica provenientes de várias instituições brasileiras de pesquisa agropecuária. O objetivo deste trabalho foi realizar a caracterização preliminar dos acessos de cafeeiros arábica, mantidos na Coleção Ativa de Germoplasma da Embrapa Rondônia em Ouro Preto d’Oeste, RO. Utilizaram-se 26 acessos (cultivares e linhagens irmãs) de C. arabica, provenientes dos principais programas de melhoramento genético do cafeeiro arábica do Brasil. Foram avaliadas 28 características por meio de descritores (morfológicos e agronômicos) mínimos diferenciadores, atualmente usados para registro ou proteção de cultivares comercial de café. A utilização conjunta da maioria dos descritores usados neste trabalho possibilitou, com relativa facilidade, discriminar fenotipicamente as cultivares cafeeiras entre si. A coloração das folhas jovens e dos frutos maduros são os descritores genéticos qualitativos mais facilmente identificáveis e que mais contribuíram na distinção eficiente dos germoplasma cafeeiros caracterizados. O uso das variáveis descritoras qualitativas (coloração dos brotos, cor dos frutos maduros, porte da planta e ciclo de maturação) foram eficientes na caracterização dos acessos estudados. De modo geral, estes resultados são concordantes com outros trabalhos similares realizados com a maioria das cultivares e,ou linhagens caracterizadas.bitstream/item/45456/1/bpd67-cafe.pd

Gluonic Correlations in Matter

We derive the analogue of the QCD low energy theorems for the scalar and pseudoscalar gluonic correlators in nuclear matter. We find that the scalar correlations are depleted while the pseudoscalar correlations are enhanced to leading order in the nuclear matter density. We briefly discuss the consequences of these findings on the QCD spectrum.Comment: 9 pages, LaTe

Nonlinear Regge trajectories and glueballs

We apply a phenomenological approach based on nonlinear Regge trajectories to glueball states. The parameters, i.e., intercept and threshold, or trajectory termination point beyond which no bound states should exist, are determined from pomeron (scattering) data. Systematic errors inherent to the approach are discussed. We then predict masses of glueballs on the tensor trajectory. For comparison, the approach is applied to available quenched lattice data. We find a discrepancy between the lattice based thresholds and the pomeron threshold that we extract from data.Comment: 15pp., revtex4, 2 fig

Glueball spectrum and the Pomeron in the Wilson loop approach

Using a nonperturbative method based on asymptotic behaviour of Wilson loops we calculate masses of glueballs and corresponding Regge-trajectories. The only input is string tension fixed by meson Regge slope, while perturbative contributions to spin splittings are defined by standard alpha_s values. The masses of lowest glueball states are in a perfect agreement with lattice results. The leading glueball trajectory which is associated with Pomeron is discussed in details and its mixing with f and f' trajectories is taken into account.Comment: LaTeX2e, 49 pages, 2 figure

Classical Inhomogeneities in String Cosmology

We generalize previous work on inhomogeneous pre-big bang cosmology by including the effect of non-trivial moduli and antisymmetric-tensor/axion fields. The general quasi-homogeneous asymptotic solution---as one approaches the big bang singularity from perturbative initial data---is given and its range of validity is discussed, allowing us to give a general quantitative estimate of the amount of inflation obtained during the perturbative pre-big bang era. The question of determining early-time ``attractors'' for generic pre-big bang cosmologies is also addressed, and a motivated conjecture is advanced. We also discuss S-duality-related features of the solutions, and speculate on the way an asymptotic T-duality symmetry may act on moduli space as one approaches the big bang.Comment: 32 pages, Revtex, 1 figure included, epsfig.sty needed; one reference adde