Multiphoton Processes in Driven Mesoscopic Systems

We study the statistics of multi-photon absorption/emission processes in a mesoscopic ring threaded by an harmonic time-dependent flux $\Phi(t)$. For this sake, we demonstrate a useful analogy between the Keldysh quantum kinetic equation for the electrons distribution function and a Continuous Time Random Walk in energy space with corrections due to interference effects. Studying the probability to absorb/emit $n$ quanta $\hbar\omega$ per scattering event, we explore the crossover between ultra-quantum/low-intensity limit and quasi-classical/high-intensity regime, and the role of multiphoton processes in driving it.Comment: 6 pages, 5 figures, extended versio

A multiband radiometer and data acquisition system for remote sensing field research

Specifications are described for a recently developed prototype multispectral data acquisition system which consists of multiband radiometer with 8 bands between 0.4 and 12.5 micrometers and a data recording module to record data from the radometer and ancillary sources. The systems is adaptable to helicopter, truck, or tripod platforms, as well as hand-held operation. The general characteristics are: (1) comparatively inexpensive to acquire, maintain and operate; (2) simple to operate and calibrate; (3) complete with data hardware and software; and (4) well documented for use by researchers. The instrument system is to be commercially available and can be utilized by many researchers to obtain large numbers of accurate, calibrated spectral measurements. It can be a key element in improving and advancing the capability for field research in remote sensing

Cryopreservation of Coffea canephora Pierre ex A. Froehner seeds: importance of drying rate and moisture content.

Seeds of the Coffea canephora species are considered more recalcitrant than those of the Coffea arabica species. They tolerate partial dehydration and they cannot be stored in conventional seed banks at -18ºC because they are sensitive to freezing temperatures. Cryopreservation is a reliable method for storing seeds with these characteristics for long periods. However, preliminary studies are necessary to determine ideal storage conditions. The aim of this study was to investigate the ideal physical and physiological conditions for cryopreservation of Coffea canephora seeds to reduce seed mortality caused by the formation of intracellular ice crystals and to avoid cell damage caused by excessive desiccation. Seeds were subjected to rapid drying in silica gel and slow drying in saturated NaCl solution to moisture contents of 0.20, 0.25, and 0.28 g.g-¹ (dry basis), followed by direct immersion in liquid nitrogen for rapid freezing. Physiological and biochemical analyses were performed to evaluate seed quality before and after cryopreservation. Rapid drying of Coffea canephora seeds to values near 0.20 g.g-1 (db) does not cause reduction in physiological quality. Moisture content of 0.25 g.g-¹ brings about greater survival of Coffea canephora seeds after cryopreservation. Drying rate affects the physiological quality of cryopreserved Coffea canephora seeds, and rapid drying in silica gel is more favorable than slow drying in a saturated NaCl solution. The activity of the enzymes catalase, esterase, glutamic oxaloacetic transaminase, and polyphenol oxidase are indicators of seed quality for Coffea canephora seeds subjected to cryopreservation

Desenvolvimento de novos microssatélites em Araucaria angustifolia via redução de complexidade genômica e sequenciamento.

Resumo

Hadronic Entropy Enhancement and Low Density QGP

Recent studies show that for central collisions the rising of the incident energy from AGS to RHIC decreases the value of the chemical potential in the Hadron-QGP phase diagram. Thus, the formation of QGP at RHIC energies in central collisions may be expected to occur at very small values of the chemical potential. Using many different relativistic mean-field hadronic models (RMF) at this regime we show that the critical temperature for the Hadron-QGP transition is hadronic model independent. We have traced back the reason for this and conclude that it comes from the fact that the QGP entropy is much larger than the hadronic entropy obtained in all the RMF models. We also find that almost all of these models present a strong entropy enhancement in the hadronic sector coming from the baryonic phase transition to a nucleon-antinucleon plasma. This result is in agreement with the recent data obtained in the STAR collaboration at RHIC where it was found a rich proton-antiproton matter

Fontes e concentrações de carbono e sais na propagação in vitro do bacurizeiro (Platonia insignis Mart.).

Objetivou-se determinar diferentes fontes e concentrações de carbono e sais na propagação do bacurizeiro (Platonia insignis Mart.), no desenvolvimento de explantes caulinares, sob condições de cultivo in vitro

Caracterização química e espectroscópica de compostos orgânicos aplicados à produção de plantas medicinais.

Devido ao potencial dos compostos orgânicos tem-se observado sua crescente utilização na agricultura. A aplicação dos diferentes compostos no solo possibilita avaliar a correlação dos parâmetros químicos e espectroscópicos e as respostas de desenvolvimento das plantas cultivadas, fornecendo bases científicas para agricultura orgânica. O objetivo deste trabalho foi avaliar as propriedades químicas e o grau de humificação de compostos orgânicos por espectroscopia de fluorescência de luz UV-vis. Os compostos A e E apresentaram maior grau de humificação.Disponível também em: Cadernos de Agroecologia, V. 5, n.1, 2010. Trabalho também apresentado in: WORKSHOP DE PLANTAS MEDICINAIS DE MATO GROSSO DO SUL, 13.; EMPÓRIO DE AGRICULTURA FAMILIAR DA GRANDE DOURADOS, 3., 2010, Dourados. Palestras e Resumos Expandidos. Dourados: UFGD, 2010