383 research outputs found

    Applications of response surface methodology approach to determine the effect of temperature, time of incubation and light conditions on germination and germ tube growth of Puccinia coronata f.sp. avenae urediosopores

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    Crown rust caused by Puccinia coronata f.sp. avenae is the most damaging disease on oat. This work analyzed the effects of temperature and illumination regime during different time of incubation on both spore germination and germ tube growth, using both analysis of variance (ANOVA) and response surface methodology (RSM). This study reveals that the maximum of germination approached 95% under dark conditions at 20°C. Similarly, the maximum germ tube length was 125±23 μm under dark conditions at the same temperature after 18 h. Both spore germination and germ tube growth were observed over a wider temperature range of 5 to 30°C. The darkness conditions seem to enhance significantly (P < 0.05) both the germination and germ tube growth. After 4 h of incubation, germination was significantly higher under darkness regime at 15, 20 and 25°C than under light conditions. The effect of darkness conditions on germ tube growth paralleled its effect on germination. Furthermore, the response surface methodology (RSM) was applied to determine the optimal conditions of temperature, time and illuminations conditions for both the germination process and germ tube growth of urediospores for P. coronata f.sp. coronata. Values for the optimal germination and germ tube growth were 20°C and 8 h under darkness conditions. Moreover, urediospores of P. coronata f.sp. coronata germination and germ tube growth had followed a quadratic response function on temperature (R² = 0.94 and 0.97). On the other hand, the experimental values were in good agreement with the predicted ones and the model was highly significant with the correlation coefficient R being 0.97 and 0.98, respectively for germination and germ tube growth.Key words: Puccinia coronata f.sp. avenae, temperature, time, illuminations conditions, germination process, germ tube growth, urediospores

    Bias behaviour and antithetic sampling in mean-field particle approximations of SDEs nonlinear in the sense of McKean

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    In this paper, we prove that the weak error between a stochastic differential equation with nonlinearity in the sense of McKean given by moments and its approximation by the Euler discretization with time-step h of a system of N interacting particles is (N-1+h). We provide numerical experiments confirming this behaviour and showing that it extends to more general mean-field interaction and study the efficiency of the antithetic sampling technique on the same examples

    Comparative aggressiveness of Mycosphaerella pinodes on peas from different regions in western Algeria

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    Mycosphaerella blight caused by Mycosphaerella pinodes (Berk. et Blox.) Vestergr. is now recognized as one of the major problems limiting yield of pea crops in Algeria. The present work was carried out to study the aggressiveness of 75 M. pinodes isolates collected from different pea-growing areas forming four population groups representing four geographic areas in western Algeria. The latent period, incubation period and disease severity were measured in the greenhouse for each isolate Ă— cultivar combination. All three aggressiveness components differed significantly between isolates and between cultivars. No significant interaction however was noted between isolates and cultivars. Both principal component analysis (PCA) and hierarchical cluster analysis (HCA) were employed to analyze the variation pattern within and between population groups. Cluster analysis, which summarizes the relationship between isolates according to their distance of similarity, sorted isolates into six distinct aggressiveness groups. Aggressiveness group 1 was the most represented, with 34% of all isolates. Both PCA and cluster analysis revealed that many isolates were closely related irrespective of the geographic area or the host cultivar from which they were collected. At the same time, and based on the same aggressiveness components, the cv. Onward, Lucy and DP were the most susceptible, whereas the cv. Rondo and MK were partially resistant

    Effect of pea cultivar, pathogen isolate, inoculum concentration and leaf wetness duration on Ascochyta blight caused by Mycosphaerella pinodes

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    The effect of host leaf wetness duration, Mycosphaerella pinodes inoculum concentration and pathogen isolate on the latent period and the incubation period of the pathogen or disease severity were quantifi ed on pea (Pisum sativum L.). Seedlings of two widely grown pea cultivars, Onward and Merveille de Kelvedon, respectively susceptible and moderately resistant to M. pinodes were subjected to six leaf wetness durations of 6, 12, 24, 48 and 72 h, and inoculated with fi ve inoculum concentrations, 2.5Ă—103, 4Ă—104, 3.5Ă—105, 4x106, and 5.2Ă—107, in order to determine whether the cultivars reacted differently to M. pinodes isolates inoculated under identical conditions. Increasing the duration of leaf wetness and inoculum concentration caused signifi cant (P<0.001) increases in disease severity within each cultivar. Both the incubation period and the latent period decreased with increasing conidial concentration and leaf wetness duration. Generally, the cv. Onward had a signifi cantly shorter incubation period, and latent period and higher disease severity than cv. Merveille de Kelvedon. Isolates differed in aggressiveness at higher levels of leaf wetness (48 h) duration and of inoculum concentration (4Ă—106), but there was no signifi cant interaction between isolates and leaf wetness duration, or between isolates and inoculum concentration. The optimum levels for obtaining a consistent infection and for readily separating the susceptible and the partially resistant cultivars were a leaf wetness of 48 h and an inoculum concentration of 4Ă—106. The study also showed that continuous leaf wetness for 48 h was a threshold for application of fungicides to control the fungus in the susceptible cultivar

    Reversibility of continuous-variable quantum cloning

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    We analyze a reversibility of optimal Gaussian 1→21\to 2 quantum cloning of a coherent state using only local operations on the clones and classical communication between them and propose a feasible experimental test of this feature. Performing Bell-type homodyne measurement on one clone and anti-clone, an arbitrary unknown input state (not only a coherent state) can be restored in the other clone by applying appropriate local unitary displacement operation. We generalize this concept to a partial LOCC reversal of the cloning and we show that this procedure converts the symmetric cloner to an asymmetric cloner. Further, we discuss a distributed LOCC reversal in optimal 1→M1\to M Gaussian cloning of coherent states which transforms it to optimal 1→M′1\to M' cloning for M′<MM'<M. Assuming the quantum cloning as a possible eavesdropping attack on quantum communication link, the reversibility can be utilized to improve the security of the link even after the attack.Comment: 7 pages, 5 figure

    On the equivalence of pairing correlations and intrinsic vortical currents in rotating nuclei

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    The present paper establishes a link between pairing correlations in rotating nuclei and collective vortical modes in the intrinsic frame. We show that the latter can be embodied by a simple S-type coupling a la Chandrasekhar between rotational and intrinsic vortical collective modes. This results from a comparison between the solutions of microscopic calculations within the HFB and the HF Routhian formalisms. The HF Routhian solutions are constrained to have the same Kelvin circulation expectation value as the HFB ones. It is shown in several mass regions, pairing regimes, and for various spin values that this procedure yields moments of inertia, angular velocities, and current distributions which are very similar within both formalisms. We finally present perspectives for further studies.Comment: 8 pages, 4 figures, submitted to Phys. Rev.

    Time-odd components in the mean field of rotating superdeformed nuclei

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    Rotation-induced time-odd components in the nuclear mean field are analyzed using the Hartree-Fock cranking approach with effective interactions SIII, SkM*, and SkP. Identical dynamical moments J(2){{\cal J}^{(2)}} are obtained for pairs of superdeformed bands 151^{151}Tb(2)--152^{152}Dy(1) and 150^{150}Gd(2)--151^{151}Tb(1). The corresponding relative alignments strongly depend on which time-odd mean-field terms are taken into account in the Hartree-Fock equations.Comment: 23 pages, ReVTeX, 6 uuencoded postscript figures include

    PT-symmetric Solutions of Schrodinger Equation with position-dependent mass via Point Canonical Transformation

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    PT-symmetric solutions of Schrodinger equation are obtained for the Scarf and generalized harmonic oscillator potentials with the position-dependent mass. A general point canonical transformation is applied by using a free parameter. Three different forms of mass distributions are used. A set of the energy eigenvalues of the bound states and corresponding wave functions for target potentials are obtained as a function of the free parameter.Comment: 13 page
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