Micropropagação de batata 'BRS Ana': produção de material básico com alta sanidade.

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Protocolos de Micropropagação de Plantas. I-Batata.

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Ingestive behaviour and forage intake responses of young and mature steers to the vertical differentiation of sugarcane in pen and grazing studies

SUMMARY Sugarcane is an important forage resource in sub-tropical and tropical areas as it is used during the winter or dry season when the growth rate of pastures is significantly reduced. The current research study assessed the effect of four vertical sections of sugarcane in a pen trial and the level of sugarcane utilization in a grazing trial on the ingestive behaviour and forage intake of two age groups of steers (1 and 2 years old). The pen trial was comprised of two simultaneous 4 × 4 balanced Latin square designs (one for each age group of animals) of four periods, four animals and four feeding treatments, which consisted of four equal vertical sections of sugarcane. Dry matter (DM) and digestible DM (DDM) intake per kilogram of metabolic weight declined gradually from top to bottom of the sugarcane, with no significant differences between the age groups of steers. This difference in intake was associated with a decline in intake of neutral detergent fibre (NDF) as a proportion of the liveweight of the animal and an increase of total chewing time per kilogram of DM or NDF from top to bottom of the sugarcane. It was concluded that the toughness of plant material played a significant role regulating intake, which was higher for the top sections of sugarcane. In the grazing trial, steers of both age groups grazed down sugarcane in three plots over 9 days. Steers grazed up to four distinctive grazing strata. Digestible DM intake (DDM intake) was high at low levels of horizontal utilization of the top grazing stratum but DDM intake started to decline sharply when this stratum was removed in 0·92 of paddock area (i.e. equivalent to 0·08 of the pasture area remaining un-grazed). It was concluded that the proportion of un-grazed area of the pasture can be used as a grazing management strategy to control forage intake for sugarcane

On the definition of a unique effective temperature for non-equilibrium critical systems

We consider the problem of the definition of an effective temperature via the long-time limit of the fluctuation-dissipation ratio (FDR) after a quench from the disordered state to the critical point of an O(N) model with dissipative dynamics. The scaling forms of the response and correlation functions of a generic observable are derived from the solutions of the corresponding Renormalization Group equations. We show that within the Gaussian approximation all the local observables have the same FDR, allowing for a definition of a unique effective temperature. This is no longer the case when fluctuations are taken into account beyond that approximation, as shown by a computation up to the first order in the epsilon-expansion for two quadratic observables. This implies that, contrarily to what often conjectured, a unique effective temperature can not be defined for this class of models.Comment: 32 pages, 5 figures. Minor changes, published versio

Dietary l-tryptophan leaves a lasting impression on the brain and the stress response

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Ageing in the critical contact process: a Monte Carlo study

The long-time dynamics of the critical contact process which is brought suddenly out of an uncorrelated initial state undergoes ageing in close analogy with quenched magnetic systems. In particular, we show through Monte Carlo simulations in one and two dimensions and through mean-field theory that time-translation invariance is broken and that dynamical scaling holds. We find that the autocorrelation and autoresponse exponents lambda_{Gamma} and lambda_R are equal but, in contrast to systems relaxing to equilibrium, the ageing exponents a and b are distinct. A recent proposal to define a non-equilibrium temperature through the short-time limit of the fluctuation-dissipation ratio is therefore not applicable.Comment: 18 pages, 7 figures, Latex2e with IOP macros; final for