To provide high-level graphical support for PVM (Parallel Virtual Machine) based program development, a complex programming environment (GRADE) is being developed. GRADE currently provides tools to construct, execute, debug, monitor and visualise message-passing parallel programs. It offers high-level graphical programming abstraction mechanism to construct parallel applications by introducing a new graphical language called GRAPNEL. GRADE also provides the programmer with the same graphical user interface during the program design and debugging stages. A distributed debugging engine (DDBG) assists the user in debugging GRAPNEL programs on distributed memory computer architectures. Tape/PVM and PROVE support the performance monitoring and visualization of parallel programs developed in the GRADE environment.

To achieve a certain degree of confidence that a given program follows its specification, a testing phase must be included in the program development process, and also a complementary debugging phase to help locating the program's bugs. This paper presents an environment which results of the composition and integration of two basic tools: STEPS (Structural TEsting of Parallel Software), which is a testing tool, and DDBG (Distributed DeBuGger), which is a debugging tool. The two tools are presented individually as stand-alone tools, and we describe how they were combined through the use of another intermediate tool: DEIPA (Deterministic re-Execution and Interactive Program Analysis). We claim that the result achieved is a very effective testing and debugging environment.

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The influence of different transparent conducting oxides (TCO) on the transverse photoelectrical properties of one-dimensional position sensitive detectors based on p-i-n amorphous silicon structures was studied. For both SnO 2 and indium tin oxide, poor quality of the p layer was revealed by secondary ion mass spectroscopy measurements. Good agreement between experimental and simulation characteristics of TCO/p-i-n structure was additionally conditioned by a strong increase in defect states at the p layer surface which can be attributed to the reduction/ oxidation process at the TCO/p interface. However, the analysis showed that under reverse bias the spectral response of the p-i-n structure is not significantly affected by different TCO layers and conditions at the TCO/p heterojunction. Nevertheless, indium tin oxide is less appropriate for a front TCO layer due to the poor reverse dark current-voltage characteristic, i.e., higher leakage current component leading to lower signal to noise ratio. © 1997 American Institute of Physics.

The behaviour of a microcrystalline p-i-n junction locally illuminated with monochromatic radiation (incident power of 50 mW/cm2) is analysed by means of numerical experiences. The model used for the two-dimensional analysis of the transport properties of a μc-Si:H p-i-n photo-detector is based on the simultaneous solution of the continuity equations for holes and electrons together with the Poisson's equation. The solution is found on a rectangular domain, taking into account the dimension perpendicular to the junction plane and one on the parallel plane. The lateral effects occurring within the structure, due to the non-uniformity of the illumination, are outlined. The results we present show that the potential profile has a linear variation from the illuminated to the dark neutral region. The lateral components of the electric field and of the current density vectors reveal to be mainly localised inside the doped layers.

We report the three-dimensional crystal structure of acidic seminal fluid protein (aSFP), a 12.9 kDa poly-peptide of the spermadhesin family isolated from bovine seminal plasma, solved by the multiple isomorphous replacement method and refined with data to 1.9 Angstrom resolution with a final R-factor of 17.3%. aSFP is built by a single CUB domain architecture, a 100 to 110 amino-acid-residue extracellular module found in 16 functionally diverse proteins. The structure of aSFP reveals that the CUB domain displays a beta-sandwich topology organised into two 5-stranded beta-sheets, each of which contain two parallel and four antiparallel strands. The structure of aSFP is almost identical to that of porcine spermadhesins PSP-I and PSP-II, which in turn show limited structural similarity with jellyroll topologies of certain virus capsid proteins. Essentially, topologically conserved residues in these proteins are those internal amino acids forming the hydrophobic core of the CUB and the jellyroll domains, suggesting their importance in maintaining the integrity of these protein folds, On the other hand, the structure of aSFP shows structural features that are unique to this protein and which may provide a structural ground for understanding the distinct biological properties of different members of the spermadhesin protein family. (C) 1997 Academic Press Limited.

Spermadhesins, 12,000-14,000 M-r mammalian proteins, include lectins involved in sperm-egg binding and display a single CUB domain architecture. We report the crystal structures of porcine seminal plasma PSP-I/PSP-II, a heterodimer of two glycosylated spermadhesins. and bovine aSFP at 2.4 Angstrom and 1.9 Angstrom resolution respectively.

{Bovine acidic seminal fluid protein (aSFP) is a 12.9 kDa polypeptide of the spermadhesin family built by a single CUB domain architecture. The CUB domain is an extracellular module present in 16 functionally diverse proteins. To determine the three-dimensional structure of aSFP, the protein was crystallized at 21 degrees C by vapor diffusion in hanging drops, using ammonium sulfate, pH 4.7, and polyethyleneglycol 4000 as precipitants, containing 10% dioxane to avoid the formation of clustered crystals. Elongated prismatic crystals with maximal size of 0.6 x 0.3 x 0.2 mm(3) diffract to beyond 1.9 Angstrom resolution and belong to space group P2(1)2(1)2, with cell parameters a = 52.4 Angstrom