Thomas Fincke und die <Emphasis Type="Italic">Geometria rotundi</Emphasis>

Thomas Fincke (January 6^th, 1561–April 24^th, 1656), born in Flensburg (Germany), was one of the very most important and significant scientists in Denmark during the seventeenth century, a mathematician and astrologer and physician in the beginning of modern science, a representative of humanism and an influentual academic organizer. He studied in Strasbourg (since 1577) and Padua (since 1583) and received his M.D. in Basel (1587), he practised as a physician throughout his life (since 1587 or 1590) and became a professor at Copenhagen (1591). But he was best known because of his Geometriae rotundi libri XIIII (1583), a famous book on plane and spherical trigonometry, based not on Euclid but on Petrus Ramus. In this influentual work, in which Fincke introduced the terms tangent and secant and probable first noticed the Law of Tangents and the so-called Newton-Oppel-Mauduit-Simpson-Mollweide-Gauss-formula, he showed himself to be „abreast of the mathematics of his time“.      

Fish assemblages and stream hydraulics: consistent relations across spatial scales and regions

General relationships between organisms and their habitat, consistent across spatial scales and regions, suggest the existence of repeatable ecological processes and are useful for the management of stream networks. From published data, we defined four guilds of European fish species with contrasting preferences for microhabitat hydraulics within stream reaches. At the scale of stream reaches and across 139 French sites (590 460 fishes sampled), we analysed how fish guild proportions were related to reach hydraulics (proportion of pools vs. riffles %POOL; median discharge by unit width Q50/W). The strongest correlations were observed between two fish guilds and %POOL (p < 0.001, r² ≥ 0.41) and between one fish guild proportion and Q50/W (p < 0.001, r² = 0.10). These reach–scale relationships were consistent across six large French basins, and consistent with the analyses made at the microhabitat scale. Therefore, microhabitat preferences for hydraulics are strong enough to generate consistent reach‐scale community responses to hydraulics across regions, despite the influence of other filters such as temperature, nutrient levels or history. The distribution of basic geomorphic features (pools, riffles) in streams and their modification (by dams, weirs and dikes) can modify the proportion of fish guilds by up to 80%, probably contributing to the long‐term decline of riffle‐dwelling species in Europe. Copyright © 2006 John Wiley & Sons, Ltd.     

Uncertainty analysis based on sensitivity applied to angle-ply composite structures

This article describes a finite element-based formulation for the statistical analysis of the response of stochastic structural composite systems whose material properties are described by random fields. A first-order technique is used to obtain the second-order statistics for the structural response considering means and variances of the displacement and stress fields of plate or shell composite structures. Propagation of uncertainties depends on sensitivities taken as measurement of variation effects. The adjoint variable method is used to obtain the sensitivity matrix. This method is appropriated for composite structures due to the large number of random input parameters. Dominant effects on the stochastic characteristics are studied analyzing the influence of different random parameters. In particular, a study of the anisotropy influence on uncertainties propagation of angle-ply composites is carried out based on the proposed approach.     

Crystallization study of chemically vapour-deposited amorphous silicon films by in situ x-ray diffraction

The solid phase crystallization kinetics of chemically vapour-deposited amorphous silicon films were studied by in situ X-ray diffraction. We determined the crystalline volume directly from the Bragg peak intensities at various times during isothermal annealing in the temperature range 578 °C < T < 658 °C. From these experiments we deduced that the crystallization was due to nucleation predominantly at the substrate-film interface followed by crystal growth perpendicular to this interface. The crystal growth rate was thermally activated with an activation energy E_v of 3.1 eV. A strong 〈111〉 preferred orientation of the growing polycrystal was observed and the grain size remained constant at about 60 nm. Evidence of stresses at the amorphous-crystalline interface during the early stages of crystallization was observed. A comparison with previous conductivity measurements is also carried out.     

Water‐Stable,Magnetic Silica–Cobalt/Cobalt Oxide–Silica Multishell Submicrometer Spheres

A method to produce monodisperse magnetic composite spheres with diameters from less than 100 nm to more than 1 μm in water solution is reported. The spheres consist of a dielectric silica core and a cobalt/cobalt oxide shell which can be protected from further oxidation with an outer shell of silica or, alternatively, they can be covered with the polymer polyvinylpyrrolidone as a stabilizer. The formation of a uniform magnetic shell proceeds with the adsorption of metallic cobalt seeds, produced by the reduction of cobalt chloride with sodium borohydride, on a self‐assembled layer of polyelectrolytes on the silica core. In the second step, an outer silica shell can be formed by the hydrolysis and condensation of (3‐aminopropyl)trimethoxysilane and tetraethoxysilane. The double‐shell composite spheres show excellent sphericity, monodispersity, and a magnetic hysteresis loop at room temperature.     

Electrophysiological properties and cholinergic responses of rat ventral oral pontine reticular neurons in vitro

This study analyses the relationship between the use of rotating instruments, the production of a smear layer and the presence of alterations to enamel microstructures. The rotating instruments used were carbide (8-12 blade) and diamond tipped (30-15 m) cutters. Cavities were made in extracted teeth. Subsequently, half the sample was analysed using the rugosimeter before and after the application of ortophosphoric acid at 35% for 15 and the other half suing a Scansion Electronic microscope (SEM). The results obtained showed on the one hand that carbide cutters leave a smoother surfacer than diamond tipped cutters, and on the other that the smear layer is eliminated better by carbide cutters compared to diamond tipped cutters. Moreover, there are no major traumatic-type alterations at the level of the enamel affecting the microstructure after the use of carbide cutters.     

Social constructivism and capacity building for environmental governance

The concept of capacity building for environmental protection and management refers to the process by which the abilities of societies to identify and solve environmental problems are developed. This work assumes a social constructivist perspective to the process of capacity building for environmental governance and thus depicts it as critically dependent on broader processes of political and socioeconomic modernization. In an attempt to depict such a process, a heuristic device is put forward as a model of capacity analysis. A theoretical discourse and new institutionalist perspectives are used to test such a model on a theoretical plane. Some preliminary conclusions are drawn from this theoretical exercise.