127 research outputs found

    Genotypic differences in cyanogenic glycosides levels of compatible Prunus persica P. Persica and incompatible P. persica P. mume combinations

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    Graft incompatibility is a phenomenon associated with complex physiological, biochemical, and genetic interactions between scion and rootstock. The main objective of this work was to assess the role of cyanogenic glycosides (CGs), amygdalin and prunasin, in the graft incompatibility of Prunus and possible biochemical effects in compounds of the phenylpropanoid pathway. Graft compatibility, amygdalin and prunasin content, phenylalanine ammonia-lyase activity, total phenolic compounds content and antioxidant activity, were studied in different graft combinations (Chimarrita/Capdeboscq; Chimarrita/Tsukuba 1; Chimarrita/Umezeiro; Maciel/Capdeboscq; Maciel/’Tsukuba 1; Maciel/Umezeiro) and ungrafted genotypes. The results indicate that there was graft incompatibility of Chimarrita and Maciel cultivars grafted into Umezeiro rootstock. Combinations identified as incompatible showed higher prunasin concentration and phenylalanine ammonia-lyase (PAL) activity in rootstock and greater concentration of total phenolics compounds and antioxidant activity in scion and rootstock. The results indicate that large differences in CGs concentration, especially prunasin, can be the graft incompatibility cause between Prunus persica and P. mume. The prunasin concentration may be considered a promising marker to predict graft compatibility between P. persica and P. mume

    Schroedinger cat-like states by conditional measurements on a beam-splitter

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    A scheme for generating Schr\"{o}dinger cat-like states of a single-mode optical field by means of conditional measurement is proposed. Feeding into a beam splitter a squeezed vacuum and counting the photons in one of the output channels, the conditional states in the other output channel exhibit a number of properties that are very similar to those of superpositions of two coherent states with opposite phases. We present analytical and numerical results for the photon-number and quadrature-component distributions of the conditional states and their Wigner and Husimi functions. Further, we discuss the effect of realistic photocounting on the states.Comment: 6 figures(divided in subfigures) using a4.st

    Adequacies And Inadequacies In The Anthropometric And Dietetic Profiles Of Preschool Children

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    Nutritional conditions and food patterns in preschool children are elements that emphasise the importance of health monitoring in this period of nutritional transition, both to ensure nutritional adequacy and how much to intervene in identified inadequacies. Hence, it may also constitute a strategy for public programs and school health services to make decisions. Objective: To analyse the anthropometric and dietary profiles of pre-schoolers of a pole city in Northeastern Brazil. Methods: This is a cross-sectional evaluative study with 114 children aged 2-5 years, of both genders, in three municipal centres of early childhood education. Anthropometry was used to measure weight and height, and the nutritional condition was assessed using the indexes Height for Age (H/A), Weight for Age (W/A), Weight for Height (W/H) and Body Mass Index for Age (BMI/A) in z-score values with classifications established by the World Health Organization. The food intake record was done by direct weighing of the food menu offered during a week in the three institutions. This procedure allowed for the evaluation of the nutritional composition of menus, from the estimates in percentages, average and standard deviations of total calories, macronutrients (proteins, carbohydrates and lipids) and micronutrients (calcium, iron, vitamins A and C), to the adjustments and comparisons to the reference values of the Recommended Dietary Allowances, National Research Council and the PNAE recommendations, by age stages, in full-time units, 1-3 years, 700 kcal; 4-5 years, 950 kcal (70% coverage prediction of daily nutritional requirements) and the part-time units, these same ranges of age, respectively, 200 and 270 kcal (20% coverage for forecasting nutritional needs daily), considering adequate consumption to that with a variation of up to 10% above or below 100% of these recommendations. Results: Most of the preschool children had adequate nutritional conditions, especially those of full-time units, with relative frequencies (W/A: 94.5%; W/H: 89.5%, BMI/A: 81.7%). There were registered also overweight percentages higher than the deficits, in the indices W/A (22.2%), P/E (33.3%) to municipal early childhood centre CMEI-A girls; the indices W/A, W/H, BMI/A (23.8% each) in CMEI B-boys. In relation to the adequacy of the food profile, there was only convergence between the offer and the recommendation of 70% coverage of the daily energy needs, for pre-schoolers of 4-5 years from the centre of full-time units (mean: 951.2 ± 172.3 kcal). As for nutrients, inadequacies had a trend in the coverage of the daily needs on the menu offered in part-time units. Conclusion: Although most children do not present indicative of nutritional risk, requires attention to food portion that was with inadequacies of nutritional condition, with emphasis on weight surplus, while the readjustments in per capita and in portions of the menu implemented in those locations.26223424

    Entanglement transformation at absorbing and amplifying four-port devices

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    Dielectric four-port devices play an important role in optical quantum information processing. Since for causality reasons the permittivity is a complex function of frequency, dielectrics are typical examples of noisy quantum channels, which cannot preserve quantum coherence. To study the effects of quantum decoherence, we start from the quantized electromagnetic field in an arbitrary Kramers--Kronig dielectric of given complex permittivity and construct the transformation relating the output quantum state to the input quantum state, without placing restrictions on the frequency. We apply the formalism to some typical examples in quantum communication. In particular we show that for entangled qubits the Bell-basis states Ψ±>|\Psi^\pm> are more robust against decoherence than the states Φ±>|\Phi^\pm>.Comment: 12 pages, revtex, 10 eps figures, minor corrections in Appendi

    Noise induced transitions in semiclassical cosmology

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    A semiclassical cosmological model is considered which consists of a closed Friedmann-Robertson-Walker in the presence of a cosmological constant, which mimics the effect of an inflaton field, and a massless, non-conformally coupled quantum scalar field. We show that the back-reaction of the quantum field, which consists basically of a non local term due to gravitational particle creation and a noise term induced by the quantum fluctuations of the field, are able to drive the cosmological scale factor over the barrier of the classical potential so that if the universe starts near zero scale factor (initial singularity) it can make the transition to an exponentially expanding de Sitter phase. We compute the probability of this transition and it turns out to be comparable with the probability that the universe tunnels from "nothing" into an inflationary stage in quantum cosmology. This suggests that in the presence of matter fields the back-reaction on the spacetime should not be neglected in quantum cosmology.Comment: LaTex, 33.tex pages, no figure

    Particle creation, classicality and related issues in quantum field theory: II. Examples from field theory

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    We adopt the general formalism, which was developed in Paper I (arXiv:0708.1233) to analyze the evolution of a quantized time-dependent oscillator, to address several questions in the context of quantum field theory in time dependent external backgrounds. In particular, we study the question of emergence of classicality in terms of the phase space evolution and its relation to particle production, and clarify some conceptual issues. We consider a quantized scalar field evolving in a constant electric field and in FRW spacetimes which illustrate the two extreme cases of late time adiabatic and highly non-adiabatic evolution. Using the time-dependent generalizations of various quantities like particle number density, effective Lagrangian etc. introduced in Paper I, we contrast the evolution in these two limits bringing out key differences between the Schwinger effect and evolution in the de Sitter background. Further, our examples suggest that the notion of classicality is multifaceted and any one single criterion may not have universal applicability. For example, the peaking of the phase space Wigner distribution on the classical trajectory \emph{alone} does not imply transition to classical behavior. An analysis of the behavior of the \emph{classicality parameter}, which was introduced in Paper I, leads to the conclusion that strong particle production is necessary for the quantum state to become highly correlated in phase space at late times.Comment: RevTeX 4; 27 pages; 18 figures; second of a series of two papers, the first being arXiv:0708.1233 [gr-qc]; high resolution figures available from the authors on reques

    Particle creation, classicality and related issues in quantum field theory: I. Formalism and toy models

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    The quantum theory of a harmonic oscillator with a time dependent frequency arises in several important physical problems, especially in the study of quantum field theory in an external background. While the mathematics of this system is straightforward, several conceptual issues arise in such a study. We present a general formalism to address some of the conceptual issues like the emergence of classicality, definition of particle content, back reaction etc. In particular, we parametrize the wave function in terms of a complex number (which we call excitation parameter) and express all physically relevant quantities in terms it. Many of the notions -- like those of particle number density, effective Lagrangian etc., which are usually defined using asymptotic in-out states -- are generalized as time-dependent concepts and we show that these generalized definitions lead to useful and reasonable results. Having developed the general formalism we apply it to several examples. Exact analytic expressions are found for a particular toy model and approximate analytic solutions are obtained in the extreme cases of adiabatic and highly non-adiabatic evolution. We then work out the exact results numerically for a variety of models and compare them with the analytic results and approximations. The formalism is useful in addressing the question of emergence of classicality of the quantum state, its relation to particle production and to clarify several conceptual issues related to this. In Paper II (arXiv:0708.1237), which is a sequel to this, the formalism will be applied to analyze the corresponding issues in the context of quantum field theory in background cosmological models and electric fields.Comment: RevTeX 4; 32 pages; 28 figures; first of a series of two papers, the second being arXiv:0708.1237 [gr-qc]; high resolution figures available from the authors on reques

    Active Brownian Particles. From Individual to Collective Stochastic Dynamics

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    We review theoretical models of individual motility as well as collective dynamics and pattern formation of active particles. We focus on simple models of active dynamics with a particular emphasis on nonlinear and stochastic dynamics of such self-propelled entities in the framework of statistical mechanics. Examples of such active units in complex physico-chemical and biological systems are chemically powered nano-rods, localized patterns in reaction-diffusion system, motile cells or macroscopic animals. Based on the description of individual motion of point-like active particles by stochastic differential equations, we discuss different velocity-dependent friction functions, the impact of various types of fluctuations and calculate characteristic observables such as stationary velocity distributions or diffusion coefficients. Finally, we consider not only the free and confined individual active dynamics but also different types of interaction between active particles. The resulting collective dynamical behavior of large assemblies and aggregates of active units is discussed and an overview over some recent results on spatiotemporal pattern formation in such systems is given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte
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