Effect of short wavelength illumination on the characteristic bulk diffusion length in ribbon silicon solar cells

The influence of short wavelength light on the characteristic bulk minority carrier diffusion length of the ribbon silicon photovoltaic cell has been investigated. We have measured the intensity and wavelength dependence of the diffusion length in an EFG ribbon cell, and compared it with a standard Czochralski grown silicon cell. While the various short wavelength illuminations have shown no influence on the diffusion length in the CZ cell, the diffusion lengths in the ribbon cell exhibit a strong dependence on the volume generate rate as well as on the wavelength of the superimposed lights. We have concluded that the trap-filling phenomenon at various depths in the bulk neutral region of the cell is consistent with the experimental observation.     

Postural changes in plasma renin activity and responses to vasoactive drugs in a case of Shy-Drager syndrome

A male aged 47 years with gross autonomic insufficiency as part of the Shy-Drager syndrome is described. He did not sweat normally when warmed, and his circulatory responses to mental arithmetic, the Valsalva manoeuvre, and head-up tilt were abnormal indicating severe sympathetic failure. During head-up tilt there was a rise in plasma renin activity and plasma aldosterone. It is argued that plasma renin activity is not dependent on sympathetic nervous activity and may be mediated by renal baroreceptors. These rises may help sustain the blood pressure in such patients during repeated head-up tilts. Infusions of L-noradrenaline and angiotension produced greater hypertension, and injections of isoprenaline greater hypotension than in controls. Although it is difficult to exclude the possibility that one factor in this may be hypersensitivity of receptors in blood vessel walls, the principal factor is likely to be the absence of those baroreflexes of which the efferent pathways are in the sympathetic nervous system.     

DDT-related compounds bound to the nonextractable particulate matter in sediments of the Teltow Canal,Germany

Sediment samples of the Teltow Canal (Berlin, Germany) were analyzed with respect to extractable and nonextractable organic compounds. The study focused on the identification and quantitation of bound 2,2-bis(chlorophenyl)-1,1,1-trichlorethane (DDT) residues in order to obtain further information about the fate of DDT-derived compounds within the particulate matter of the aquatic environment. Various chemical degradation techniques and a complementary online pyrolysis-GC/MS method were applied to the pre-extracted sediment residues. Generally, the distribution of the bound DDT-related compounds was found to differ distinctly from the substances distribution within the extractable fraction. The main metabolite of the anaerobic degradation pathway (2,2-bis(chlorophenyl)-1,1-dichlorethane, DDD) is most abundant in the sediment extracts but occurred only in insignificant concentrations in the degradation products of all procedures applied. The most abundant DDT-metabolites released after the degradation procedures were 4,4'-DBP, 4,4'-DDA, and 4,4'-DDM. In addition, 4,4'-DDM was detected at rather high concentrations by pyrolytic analysis. The results imply a weak association to the nonextractable particulate matter based on noncovalent interactions for the observed DDT-related contaminants. The release of these compounds was initiated by the modification and degradation of the organic macromolecular matrix as well as of the inorganic material. Furthermore, numerous methoxychlor-related compounds were detected not only in the extracts but also in parts of the hydrolysis products.     

Development of surgical instruments for implanting a flexible fixation device for the lumbar spine

A new flexible fixation device for the lumbar spine has been developed. This paper describes the development and evaluation of two surgical instruments required for implanting this device. Prototypes were designed, manufactured and then evaluated for use in surgery. Further evaluation was performed, if necessary, and the design finalized, in accordance with BS EN 12011. This process involved close collaboration between engineers and surgeons.     

Optimizing resources in model selection for support vector machine

Tuning support vector machine (SVM) hyperparameters is an important step in achieving a high-performance learning machine. It is usually done by minimizing an estimate of generalization error based on the bounds of the leave-one-out (LOO) such as radius-margin bound and on the performance measures such as generalized approximate cross-validation (GACV), empirical error, etc. These usual automatic methods used to tune the hyperparameters require an inversion of the Gram-Schmidt matrix or a resolution of an extra-quadratic programming problem. In the case of a large data set these methods require the addition of huge amounts of memory and a long CPU time to the already significant resources used in SVM training. In this paper, we propose a fast method based on an approximation of the gradient of the empirical error, along with incremental learning, which reduces the resources required both in terms of processing time and of storage space. We tested our method on several benchmarks, which produced promising results confirming our approach. Furthermore, it is worth noting that the gain time increases when the data set is large.     

High-Quality Adaptive Soft Shadow Mapping

The recent soft shadow mapping technique [ [GBP06] ] allows the rendering in real-time of convincing soft shadows on complex and dynamic scenes using a single shadow map. While attractive, this method suffers from shadow overestimation and becomes both expensive and approximate when dealing with large penumbrae. This paper proposes new solutions removing these limitations and hence providing an efficient and practical technique for soft shadow generation. First, we propose a new visibility computation procedure based on the detection of occluder contours, that is more accurate and faster while reducing aliasing. Secondly, we present a shadow map multi-resolution strategy keeping the computation complexity almost independent on the light size while maintaining high-quality rendering. Finally, we propose a view-dependent adaptive strategy, that automatically reduces the screen resolution in the region of large penumbrae, thus allowing us to keep very high frame rates in any situation.     

Constructing and visualizing chemical reaction networks from pi-calculus models

The π-calculus, in particular its stochastic version the stochastic π-calculus, is a common modeling formalism to concisely describe the chemical reactions occurring in biochemical systems. However, it remains largely unexplored how to transform a biochemical model expressed in the stochastic π-calculus back into a set of meaningful reactions. To this end, we present a two step approach of first translating model states to reaction sets and then visualizing sequences of reaction sets, which are obtained from state trajectories, in terms of reaction networks. Our translation from model states to reaction sets is formally defined and shown to be correct, in the sense that it reflects the states and transitions as they are derived from the continuous time Markov chain-semantics of the stochastic π-calculus. Our visualization concept combines high level measures of network complexity with interactive, table-based network visualizations. It directly reflects the structures introduced in the first step and allows modelers to explore the resulting simulation traces by providing both: an overview of a network’s evolution and a detail inspection on demand.     

Continuous assessments of pressure comfort on a train - A field-laboratory comparison

Pressure variations on a train predominantly occur while trains are passing through tunnels. These aerodynamic effects may give rise to aural discomfort in railway passengers. We conducted a field study on the high speed railway track Cologne-Frankfurt/Main as well as a simulation study in our pressure chamber TITAN (DLR-Institute of Aerospace Medicine) with 31 subjects (mean age?=?37.7, SD?=?12.7; 51.6% male) to investigate pressure comfort for passengers. Continuous assessments of pressure events using sliders and retrospective assessments were acquired. Pressure variations were mostly tolerated. A comparison of field and laboratory setting revealed high congruency of continuous as well as retrospective assessments. A generalized estimating equation model identified pressure change attributes contributing to passengers' discomfort. Beside attributes of instantaneous pressure changes (e.g. high amplitudes, short durations), pressure events of the recent past significantly influenced current discomfort. Design engineers may use these findings to improve train and tunnel design.     

A dual-affinity gene fusion system to express small recombinant proteins in a soluble form: expression and characterization of protein A deletion mutants

A novel gene fusion system to express and purify small recombinantproteins in Escherichia coli has been constructed. The conceptallows for affinity purification of soluble gene products bysequential albumin- and Zn²+-affinity chromatography. The dual-affinitysystem is well suited for expression of unstable proteins asonly full-length protein is obtained after purification andproteins gain proteolytic stability in the fusion protein. Herewe show that the dual-affinity approach can be used for theexpression of various unstable derivatives of a single IgG-bindingdomain based on staphylococcal protein A. Analysis of the proteolyticstabilities and the IgG-binding properties of the differentmutant proteins suggest that the model for the structure ofan IgG-binding domain must be re-evaluated.