Timed Concurrent Constraint Programming for Analysing Biological Systems

In this paper we present our first approach to model and verify biological systems using ntcc, a concurrent constraint process calculus. We argue that the partial information constructs in ntcc can provide a suitable language for such systems. We also illustrate how ntcc may provide a unified framework for the analysis of biological systems, as they can be described, simulated and verified using the elements provided by the calculus.     

Power plant investment in restructured markets

Investment opportunities in electric power generation have changed dramatically since electricity industry restructuring first began. In contrast to regulated utilities adding capacity in line with central planning and regulation, power plant investment is now more often made by independent companies who market power across multiple utility jurisdictions. Because the regulatory approval process is long and outcomes uncertain, developers often plan multiple options for a given development budget. As more information is revealed about the future prospects at different sites, options are abandoned sequentially until only projects that will be completed remain. In this paper we evaluate the decision to build new generation facilities in a changing and uncertain regulatory environment. We estimate hazard rates for new power plant projects using a database of generation projects in North America and examine in greater detail the development patterns in California and Texas, two states with very different regulatory regimes. We find that regulatory uncertainty significantly affects the pattern of development in the electric power generation industry.     

Euclidean push–pull partial covering problems

This paper considers a bicriteria model to locate a semi-obnoxious facility within a convex polygon. Assuming that a given number of closest points and farthest points may be neglected in the analysis, it considers simultaneously the resulting push and pull partial covering criteria with Euclidean distances. Although both objectives are neither concave or convex, low complexity polynomial algorithms to find all the efficient solutions and the tradeoffs involved are developed by way of higher-order Voronoi diagrams. Comparison of the tradeoff for full covering and partial covering enables decision makers to understand to what extent the maximin and minimax criteria are improved at the expense of neglecting some points. The extensions to different sets of points pulling and pushing the facility and to weighted points are discussed. All methods are illustrated via small scale examples.     

A new system for computer-aided preoperative planning and intraoperative navigation during corrective jaw surgery.

A new system for computer-aided corrective surgery of the jaws has been developed and introduced clinically. It combines three-dimensional (3-D) surgical planning with conventional dental occlusion planning. The developed software allows simulating the surgical correction on virtual 3-D models of the facial skeleton generated from computed tomography (CT) scans. Surgery planning and simulation include dynamic cephalometry, semi-automatic mirroring, interactive cutting of bone and segment repositioning. By coupling the software with a tracking system and with the help of a special registration procedure, we are able to acquire dental occlusion plans from plaster model mounts. Upon completion of the surgical plan, the setup is used to manufacture positioning splints for intraoperative guidance. The system provides further intraoperative assistance with the help of a display showing jaw positions and 3-D positioning guides updated in real time during the surgical procedure. The proposed approach offers the advantages of 3-D visualization and tracking technology without sacrificing long-proven cast-based techniques for dental occlusion evaluation. The system has been applied on one patient. Throughout this procedure, we have experienced improved assessment of pathology, increased precision, and augmented control.     

Re‐evaluation of the Optimal Operating Conditions for the Primary End of an Integrated Steel Plant using Multi‐objective Genetic Algorithms and Nash Equilibrium

Some existing work on optimizing the operational cost of the primary end of an integrated steel plant containing two blast furnaces utilizing both pellets and sinters, an electric furnace and a basic oxygen furnace was further advanced using a multi‐objective genetic algorithm, along with a Nash equilibrium analysis. The new formulation was able to improve the earlier results very significantly, suggesting the efficacy of the multi‐objective approach over the more conventional single objective genetic algorithms.     

Children's attributions in the family: The Children's Relationship Attribution Measure.

This study assessed children's attributions in parent–child relationships, examined their association with relationship positivity and behavior displayed toward the parent, determined whether depressive symptoms account for these associations, and investigated whether parent and child attributions are linked. Ten- to 12-year-old children (116 girls, 116 boys) completed several questionnaires and were observed during parent–child interactions. Children's attributions for parent behavior were related to positivity of the parent–child relationship and to self- and parent-reported conflict and observed behavior with the father. These associations were not due to children's depressive symptoms but potentially augment our understanding of the effect of depression on parent–child relationships. Finally, gender moderated the parent attribution–child attribution association. The results underscore the importance of children's perceptions of family processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Postoperative spondylodiscitis as the cause of failed-back syndrome--clinical aspects, diagnosis, therapy

OBJECTIVES: The choice of cell line for in vitro biological tests which assess the cytotoxicity of dental materials remains controversial, yet this issue is important because these tests are widely used to rate the biocompatibility of new and existing materials, and many different cell lines are commonly used. The purpose of the current study was to quantify the responses of four cell lines (Balb/c 3T3, L929, ROS 17/2.8 and WI-38) to 14 metal ions which are released from dental materials, and relate these responses to the metabolic activity and population doubling times of these cells. METHODS: Succinic dehydrogenase (SDH) activity was used to monitor metabolic activity and cytotoxic response. RESULTS: The cell lines responded differently to most metal ions. In general, the Balb/c 3T3 line was the most sensitive, and the WI-38 line was the least sensitive. However, there were many exceptions depending on the metal ion. The passage number of the cells also affected the cytotoxic response. It was concluded that the cytotoxicity of materials which release metal ions will be significantly different depending on which cell line is selected and its passage number. SIGNIFICANCE: Based on the findings that cell lines ranked the toxicities of the metal ions similarly, it seems reasonable to use these types of in vitro tests to rank the cytotoxicities of materials. However, if these types of tests are used to predict in vivo cytotoxicity, care should be taken to choose conditions and cells which are relevant.     

Effects of salicylic acid on plant-water relationships

Soybean seedlings [Glycine max (L.) Merr.] were used as the test species to study the allelopathic influence of salicylic acid (SA) on short- and long-term plant water status. Plants were grown in greenhouse conditions in nutrient culture medium amended with SA. Treatments were initiated 10 days after germination and continued for either 14 or 28 days. The threshold for inhibition of seedling growth over a 28-day treatment was 0.15 mM SA. Seedlings grown with 0.3 mM SA consistently had higher leaf diffusive resistance and lower transpiration and water potentials than control plants. The stable carbon isotope ratio (¹³C:¹²C) in tissue from both the 0.15 and 0.30 mM SA-treated plants was significantly higher than control seedlings, indicating SA caused a chronic water stress during the 28-day treatment. These data show that an interference with plant-water relationships is one mechanism whereby this allelochemical inhibits plant growth.This study was supported by National Science Foundation grant STI-8902066.