38 research outputs found
A Cellular Automata Model for Citrus Variagated Chlorosis
A cellular automata model is proposed to analyze the progress of Citrus
Variegated Chlorosis epidemics in S\~ao Paulo oranges plantation. In this model
epidemiological and environmental features, such as motility of sharpshooter
vectors which perform L\'evy flights, hydric and nutritional level of plant
stress and seasonal climatic effects, are included. The observed epidemics data
were quantitatively reproduced by the proposed model varying the parameters
controlling vectors motility, plant stress and initial population of diseased
plants.Comment: 10 pages, 10 figures, Scheduled tentatively for the issue of: 01Nov0
Three applications of path integrals: equilibrium and kinetic isotope effects, and the temperature dependence of the rate constant of the [1,5] sigmatropic hydrogen shift in (Z)-1,3-pentadiene
Recent experiments have confirmed the importance of nuclear quantum effects
even in large biomolecules at physiological temperature. Here we describe how
the path integral formalism can be used to describe rigorously the nuclear
quantum effects on equilibrium and kinetic properties of molecules.
Specifically, we explain how path integrals can be employed to evaluate the
equilibrium (EIE) and kinetic (KIE) isotope effects, and the temperature
dependence of the rate constant. The methodology is applied to the [1,5]
sigmatropic hydrogen shift in pentadiene. Both the KIE and the temperature
dependence of the rate constant confirm the importance of tunneling and other
nuclear quantum effects as well as of the anharmonicity of the potential energy
surface. Moreover, previous results on the KIE were improved by using a
combination of a high level electronic structure calculation within the
harmonic approximation with a path integral anharmonicity correction using a
lower level method.Comment: 9 pages, 4 figure
A multiple species approach to biomass production from native herbaceous perennial feedstocks
Reproducing Deep Tunneling Splittings, Resonances, and Quantum Frequencies in Vibrational Spectra From a Handful of Direct Ab Initio Semiclassical Trajectories
Comparative analysis of the properties of composite mortar with addition of rubber powder from worn tires
This study compares the performance of two plastering mortars. The first one was produced at a 1:6 proportion of quicklime powder and sand (by volume) and ripened. The second had the same proportion but underwent a water withdrawal process in the oven. The mortars were given the same content of cement, making the proportion 1:1.5:9 (by volume), and the addition of rubber powder from worn tires at the proportions of 6%, 8%, 10% and 12% by aggregate volume. Axial compressive strength, flexural strength, deformation energy, void content, water absorption by capillarity, restrained shrinkage, and tensile bond strength were measured. The results showed that the second mortar, with rubber waste, performed better than the ripened mortar. With a reduction in the absorption of water by capillarity in the restrained shrinkage and in the void content, it maintained the tensile bond strength. The energy of deformation rose, although the compressive strength dropped