Comparison of Josephson vortex flow transistors with different gate line configurations

We performed numerical simulations and experiments on Josephson vortex flow transistors based on parallel arrays of YBa2Cu3O(7-x) grain boundary junctions with a cross gate-line allowing to operate the same devices in two different modes named Josephson fluxon transistor (JFT) and Josephson fluxon-antifluxon transistor (JFAT). The simulations yield a general expression for the current gain vs. number of junctions and normalized loop inductance and predict higher current gain for the JFAT. The experiments are in good agreement with simulations and show improved coupling between gate line and junctions for the JFAT as compared to the JFT.Comment: 3 pages, 6 figures, accept. for publication in Appl. Phys. Let

Balances of bioelements in useful tropical plants.

The productivity of different useful tropical plants is compared with respect to their biomass production. Furthermore, analyses of nutrient contents serve to explain the interrelationship between nutrient supply and primary production. The biomass and nutrient contents from three to six month old plants from Bertholletia excelsia H.B.K. (castanha-do-Brasil), Cedrela odorata L. (cedro vermelho), Dipteryx alata (cumaru), Theobroma grandiflorum (Spreng.) K. Schum. (cupuacu), Elaeis guineensis Jacq. (dende), Swietenia macrophylla King (mahogany), Sclerobium paniculatum Vogel (taxi branco) and Bixa orellana L. (urucum) within the different plant fraction were determined. The elements Ca, Mg, K, Na, Fe, Al, Zn, Cu, and P were analysed with the inductively coupled argon plasma with optical-emission-spectrometry (ICP-OES) method. Compared to plants of temperate regions, the mineral content is distinctly higher than that for tropical plants, but most values still lie within the range of existing data. Extremely high values were found for aluminium and iron

Biomass production and mineral element supply of selected useful tropical plants.

This current investigation is part of a cooperative project of CPAA-Manaus and Hamburg University entitled "Recultivation of degraded and abandoned monocultures instable mixed cultures with special reference to soil biological factors". In this study the biomass product and the mineral element supply of selected useful tropical plants will be determined. Parallel to it the availability of nutrient element in the soil will be analyzed. These experiments may allow an evaluation, in which way a sustainable growth of the suggested plant system under the prevailing site conditions is possible.Poster 11

Exogenous Influences on the Growth Dynamics of High Quality Timber Species from the Amazon .

In this study special attend was given to the important species for high quality wood production Swietenia macrophylla, Carapa guianensis, and Cedrela odorata (Meliaceae)

One-dimensional quantum chaos: Explicitly solvable cases

We present quantum graphs with remarkably regular spectral characteristics. We call them {\it regular quantum graphs}. Although regular quantum graphs are strongly chaotic in the classical limit, their quantum spectra are explicitly solvable in terms of periodic orbits. We present analytical solutions for the spectrum of regular quantum graphs in the form of explicit and exact periodic orbit expansions for each individual energy level.Comment: 9 pages and 4 figure

Adaptability of the fine root system of Ceiba pentandra (L.) Gaertn. to various sites of central Amazônia, Brazil

Ceiba pentandra (L.) Gaertn. (sumaúma), an economically important tree species in central Amazônia, stands out on account of its considerable ecological capacity of adapting to different site conditions. It can survive under seasonally dry conditions on terra firme as well as in the seasonally inundated várzea. Particularly the fine roots can structurally adapt to different soil conditions. The adaptation of the fine roots to terra firme condition results in the formation of an aerenchyma consisting of only small intercellular canals. During the dry months the walls of the epidermis cells increase in thickness and moreover they lignify and the exodermis suberize to prevent drainage. On the other hand the fine roots growing on várzea sites form lysigenously an aerenchyma consisting of extended and large intercellulars both within the cortex and the central cylinder. This large intercellular system supplies the plant with water and mineral elements and maintains the oxygen supply enabling photosynthesis throughout the year. In addition, above the soil surface numerous adventitious roots grow during the inundation period developing only small intercellular spaces within the cortex. Suberization is missing and only the primary xylem lignifies.A simulation of the fine root study under similar growth conditions in a tropical greenhouse completely confirmed the structural adaptations of the fine roots to dry and seasonally inundated conditions. This ecological amplitude is important for the selection of Ceiba pentandra for sustainably managed forestry systems

Adaptability of the fine root system of Ceiba pentandra (L.) Gaertn. to various sites of central Amazônia, Brazil.

The objective of the following study of this commercially important species was to find out in how far dynamic adaptation of the growth and structure of the fine roots can contribute to that outstanding ecological amplitude. The structural study of the fine roots from trees from terra firme and várzea in different seasons in combination with a simulation of drought and inundation conditions in the greenhouse with young plants were expected to help explain the species extensive ecological amplitude

Balanço de nutrientes de diferentes espécies arbóreas com potencial para reflorestamento.

0 presente trabalho tem como objetivos determinar a biomassa das espécies Swietenia macrophylla, Carapa guianensis, Cedrela odorata, Dipterix odorata, Hymenea courbaril, Ceiba pentandra, Virola surinamensis e Tabebuia heptaphylla em diferentes sistemas de plantacão (monocultivo, sistema agroflorestal misto e enriquecimento de linhas de capoeira), as respectivas exigencias nutricionais, o acumulo de nutrientes nas diferentes partes da planta, bem como estudar o consumo de água e a dinâmica de crescimento (principalmente a formacão de madeira)