Bloch Oscillation under a Bichromatic Laser: Quasi-Miniband Formation, Collapse, and Dynamical Delocalization and Localization

A novel DC and AC driving configuration is proposed for semiconductor superlattices, in which the THz AC driving is provided by an intense bichromatic cw laser. The two components of the laser, usually in the visible light range, are near but not exactly resonant with interband Wannier-Stark transitions, and their frequency difference equals the Wannier-Stark ladder spacing. Multi-photon processes with the intermediate states in the conduction (valence) band cause dynamical delocalization and localization of valence (conduction) electrons, and the corresponding formation and collapse of the quasi-minibands.Comment: 4 pages, 3 figure

Avaliação da resistência à ferrugem em progênies de cafeeiro F4 obtidas por cruzamentos de 'icatu' com catimor.

Com o objetivo de selecionar progênies de cafeeiro resistentes à ferrugem foram instalados e conduzidos experimentos em Três Pontas, São Sebastião do Paraíso e Machado. Foram avaliadas 17 progênies desenvolvidas pelo programa de Melhoramento Genético do Cafeeiro em Minas Gerais, coordenado pela EPAMIG e obtidas pelo cruzamento ?Icatu? x Catimor, e a cultivar Rubi MG 1192 utilizada como testemunha. O delineamento foi o de blocos casualizados com três repetições. Foram analisadas as características incidência da ferrugem no primeiro semestre de 2006.Os resultados obtidos permitem verificar que as progênies avaliadas apresentam variabilidade para a resistência a ferrugem, isso é confirmado pelas estimativas da herdabilidade que foram de boa magnitude, chegando até o valor de 92,8%. Essa condição aliada à baixa incidência da doença apresentada por algumas progênies, demonstrou que é possível selecionar progênies superiores em relação à resistência a ferrugem na população estudada

Effect of nonlinearity on the dynamics of a particle in dc field-induced systems

Dynamics of a particle in a perfect chain with one nonlinear impurity and in a perfect nonlinear chain under the action of dc field is studied numerically. The nonlinearity appears due to the coupling of the electronic motion to optical oscillators which are treated in adiabatic approximation. We study for both the low and high values of field strength. Three different range of nonlinearity is obtained where the dynamics is different. In low and intermediate range of nonlinearity, it reduces the localization. In fact in the intermediate range subdiffusive behavior in the perfect nonlinear chain is obtained for a long time. In all the cases a critical value of nonlinear strength exists where self-trapping transition takes place. This critical value depends on the system and the field strength. Beyond the self-trapping transition nonlinearity enhances the localization.Comment: 9 pages, Revtex, 6 ps figures include

Produção de batata no Rio Grande do Sul.

bitstream/item/30792/1/circular-48.pd

Surface albedo from Landsat 5 images in areas of sugar cane and cerrado

Propôs-se, neste trabalho, estimar dados de albedo à superfície terrestre usando-se o sensor Thematic Mapper (TM) do satélite LANDSAT 5 e compará-lo com dados de duas estações agrometeorológicas localizadas em região de Cerrado e a outra em cultivo da cana-de-açúcar. A região de estudo está localizada no município de Santa Rita do Passa Quatro, SP, Brasil. Para a realização do estudo obtiveram-se seis imagens orbitais do satélite Landsat 5 sensores TM, na órbita 220 e ponto 75, nas datas de 22/02, 11/04, 29/05, 01/08, 17/08 e 21/11, todas do ano de 2005, a que correspondem os dias juliano de 53, 101, 149, 213, 229 e 325, respectivamente. As correções geométricas para as imagens foram realizadas e geradas as cartas de albedo. O algoritmo SEBAL estimou satisfatoriamente os valores de albedo de superfícies sobre áreas de cerrado e de cana-de-açúcar, na região de Santa Rita do Passa Quatro, SP, consistentes com observações realizadas do albedo à superfície.This study aimed to estimate albedo data from the land surface sensor using the images of Thematic Mapper (TM) satellite LANDSAT 5 and to compare it with data from two agrometeorological stations located in the region of Cerrado, and another in sugar cane cultivation. The study area is located in the municipality of Santa Rita do Passa Quatro - SP, Brazil. To carry out the study six orbital images were obtained from the satellite Landsat 5 TM sensors in the orbit 220 and in the section 75, for the dates of 22/02, 11/04, 29/05, 01/08, 17/08 and 21/11 (all in the year of 2005) which correspond to the days 53, 101, 149, 213, 229 and 325, respectively. The geometric correction for images was performed and the letters of albedo were generated. The algorithm SEBAL estimated, satisfactorily, the values of albedo on the surface areas of Cerrado and sugar cane in the region of Santa Rita do Passa Quatro - SP, consistent with observations made of the surface albedo

BRSIPR Bel: cultivar de batata para chips com tubérculos de boa aparência.

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Exact Solution of an Evolutionary Model without Ageing

We introduce an age-structured asexual population model containing all the relevant features of evolutionary ageing theories. Beneficial as well as deleterious mutations, heredity and arbitrary fecundity are present and managed by natural selection. An exact solution without ageing is found. We show that fertility is associated with generalized forms of the Fibonacci sequence, while mutations and natural selection are merged into an integral equation which is solved by Fourier series. Average survival probabilities and Malthusian growth exponents are calculated indicating that the system may exhibit mutational meltdown. The relevance of the model in the context of fissile reproduction groups as many protozoa and coelenterates is discussed.Comment: LaTeX file, 15 pages, 2 ps figures, to appear in Phys. Rev.

First report of Phytophthora infestans self fertile genotypes in southern Brazil.

During the autumn of 2011 and 2012, leaf and stem samples of potato plants infected with P. infestans were collected in southern Brazil. Monosporangial isolates of P. infestans were obtained from the samples and mating types were determined. Each isolate was paired with the A2 and A1 mating types of P. infestans and self-paired on Petri plates containingV8 juice agar. After this, the plates were kept at 18°C in darkness for 20 days. Three isolates collected in Paraná State (municipalities of Ponta Grossa 25°12'26''S, 50°07'11''W; Contenda 25°38'52''S, 49°34'26''W; and Castro 24°51'50''S, 49°53'50''W) formed oospores when paired with both mating type isolates and also when self-paired

Dynamics of an electron in finite and infinite one dimensional systems in presence of electric field

We study,numerically, the dynamical behavior of an electron in a two site nonlinear system driven by dc and ac electric field separately. We also study, numerically, the effect of electric field on single static impurity and antidimeric dynamical impurity in an infinite 1D chain to find the strength of the impurities. Analytical arguments for this system have also been given.Comment: File Latex, 8 Figures available on reques