Peptides derived from collagen: new biochemical markers of bone metabolism]

OBJECTIVE: To study a possible association of the Helicobacter pylori seroprevalence with ABO(H) and Lewis (a,b) blood group phenotypes in blood donors. DESIGN: A cross-sectional study of blood donors using ABO(H) and Lewis (a,b) blood group phenotype as predictors. METHODS: ABO(H) and Lewis (a,b) blood group phenotyping was performed with monoclonal antibody. The H. pylori immunoglobulin G (IgG) antibody relative activity was evaluated by enzyme-linked immunosorbent assay (ELISA) using acid glycine extract from H. pylori. SUBJECTS: One hundred and fifty-nine randomly selected blood transfusion donors. RESULTS: The individuals with Lewis (a+b-)/non-secretor phenotype showed a significantly higher proportion of the H. pylori-seronegative subjects and a lower IgG immune response to H. pylori antigens as compared with the individuals of Lewis (a-b+)/secretor phenotype. CONCLUSION: The Lewis (a,b) histo-blood group antigens are implicated in the mechanisms of naturally occurring resistance to H. pylori infection.     

The microstructural and hardening behaviour of tricalcium silicate pastes in the presence of calcium chloride

A sequential examination of strength development in terms of microhardness was studied during paste hydration of C₃S in the presence of 2 and 5% CaCl₂ and at w/s ratios of 0.3 or 0.5. An attempt has been made to relate strength with microstructural features studied by means of Scanning Electron Microscopy. Generally, at earlier periods it was found that the 2% addition of CaCl₂ gave the strongest material; the effect was most pronounced in the 6-month sample of the series with 0.3 w/s. The high strength for the sample prepared at a w/s ratio of 0.3 may be related to a high CaO/SiO₂ C-S-H-phase, low porosity, and possibly a hydrated calcium hydroxy chloride complex. The pore size distribution was also measured. In general, the higher the porosity the lower the strengths but the relationship was not perfectly linear even on the semi-logarithmic plot.     

Expanding the concept of simulator fidelity: the use of technology and collaborative activities in training maritime officers

The theoretical contribution of this paper lies in introducing the concept of social fidelity to bridge the gap between computer technology and collaborative learning activities in simulator-based training. The concept has usually been limited to the technological aspects of simulator training with an assumption that a high level of fidelity equals a high physical resemblance between a simulator and the real work environment. The objective of this article is to expand the prevailing understanding of the concept of simulator fidelity and explore social factors that may influence perceived training quality among professional maritime officers. This qualitative study aims to broaden the scope from technological aspects to an emphasis on task and collaborative factors. The empirical material used is based on observations of two different simulator programs for professional maritime officers and focused interviews with bridge officers participating in the sampled training. The research aims to deepen the knowledge on how learning unfolds in a simulator-based training context characterised by extensive use of advanced computer technology and collaborative activities. The research demonstrates how trainer–trainee interactions, task factors and simulator technology may influence perceived level of fidelity and training quality. The article is concluded by offering a set of recommendations for future design of maritime simulator-based training.     

Large-scale radon hazard evaluation in the Oslofjord region of Norway utilizing indoor radon concentrations, airborne gamma ray spectrometry and geological mapping

We test whether airborne gamma ray spectrometer measurements can be used to estimate levels of radon hazard in the Oslofjord region of Norway. We compile 43,000 line kilometres of gamma ray spectrometer data from 8 airborne surveys covering 10,000 km² and compare them with 6326 indoor radon measurements. We find a clear spatial correlation between areas with elevated concentrations of uranium daughters in the near surface of the ground and regions with high incidence of elevated radon concentrations in dwellings. This correlation permits cautious use of the airborne data in radon hazard evaluation where direct measurements of indoor radon concentrations are few or absent. In radon hazard evaluation there is a natural synergy between the mapping of radon in indoor air, bedrock and drift geology mapping and airborne gamma ray surveying. We produce radon hazard forecast maps for the Oslofjord region based on a spatial union of hazard indicators from all four of these data sources. Indication of elevated radon hazard in any one of the data sets leads to the classification of a region as having an elevated radon hazard potential. This approach is inclusive in nature and we find that the majority of actual radon hazards lie in the assumed elevated risk regions.     

Measuring the Heavens: Charles S. Peirce and Astronomical Photography

Taking its point of departure from the current digitisation of the Harvard Astronomical Plate Collection, this article follows the plates back to the time when the status of photography as a research tool for astronomers was still to be established. It focuses on Charles S. Peirce, who, while employed by the US Coast Survey, made astronomical observations and contributed to the deliberation over visual and photographic methods. Particular attention is paid to Peirce’s involvement in early explorations of photography’s potential as a measurement tool. The guiding assumption is that approaching photography as a tool, rather than as a sign or representation, offers new inroads into the old problem of photography’s revealing powers and its capacity to serve as a means of discovery in science. Drawing on Peirce’s scientific practice as an alternative resource for theory construction, this article contributes to the ongoing efforts to conceptualise the productive or generative dimension of photographic methods. It concludes by pointing to the diagrammatic notion of evidence developed late in Peirce’s philosophical career, proposing that photography be reconceived as a diagrammatic tool.     

Simulation of 3D flow with gravity forces in a porous medium

Recently an operator splitting technique for convection diffusion equations, originating in porous medium flow, has been developed and analysed for one and two space dimensional models. The method is based on a solution of a modified hyperbolic problem which is used to approximate the original equation in a second step. The main objective of this paper is to investigate these algorithms for three dimensional porous media models, where handling of the gravity term is a main issue. The balance between the external pressure and the gravity may give a velocity field which is vanishing and may change sign in parts of the computational domain. This type of problem is dificult to solve accurately. Two different solution approaches are tested for accuracy, stability and computational costs. Received: 29 June 1998 / Accepted: 11 February 2000     

A model for transport of hydrogen sulfide in oil- and water-saturated porous media

In several oilfields, reservoir souring by generation of hydrogen sulfide (H₂S) occurs in secondary recovery during which seawater is injected into originally sweet reservoirs. At the production site, high concentrations of H₂S can cause severe damage to both equipment and human personnel. Proper modeling of H₂S concentration in produced fluids can be useful for decision-making during field development design. We present a model for the transport of H₂S in an oil- and water-saturated, water-wet porous medium. The different retardation mechanisms for the H₂S are described. For the adsorption of H₂S to rock, we include two distinct phases of adsorption. In addition, we introduce a functional relationship between adsorption capacity and permeability. As H₂S mixes with oil, fractions become immobile as part of the residual oil.     

The design and implementation of Neuma, a collaborative Digital Scores Library

This paper presents the design and implementation of the Neuma platform, a digital library devoted to the preservation and dissemination of symbolic music content (scores). Neuma is open to musicologists, musicians, and music publishers. It consists of a repository dedicated to the storage of large collections of digital scores, where users/applications can upload their documents. It also proposes services to publish, annotate, query, transform, and analyze scores. The long-term goal of the project is to enable an open and collaborative space where musician communities will be able to share music in symbolic notation. The project is organized around the French IRPMF institute (BnF–CNRS) which chooses and produces collections (or corpora), collects and organizes user requirements, and validates new publications. We describe the architecture of Neuma and develop some of its salient features: score modeling annotations, search and transformation language, collaborative and community tools, and digital rights preservation. We illustrate these features with two collections published by Neuma, and discuss the impact of such on-line score collections from a musicological perspective.     

Implicit treatment of molar mass equations in secondary oil migration

The hydrocarbon migration can be described by a coupled set of partial differential equations describing the dynamics of the temperature, component flow, pressure and velocity. A sequential solution procedure where the component flow is solved explicitly, gives severe restrictions on the time step given by the CFL condition. In this paper an implicit solution procedure is given and results from numerical tests are presented. The results are compared with the explicit solutions. As expected the implicit algorithm allows for substantially larger time steps. Received: 31 January 2001 / Accepted: 30 September 2001