Aging and the restructuring of precued movements.

A precue paradigm was used to examine the time it takes to restructure a planned motor response. Two groups of subjects, a young group and an elderly group, performed an aiming task in which 75% of the trials involved no change of movement parameters. On remaining trials, subjects had to change one or more of the movement parameters. Elderly subjects had slower reaction times (RTs), movement times, and made more errors in both conditions. Elderly subjects had proportionally longer RTs overall, independent of restructuring a movement plan. Preparation of arm and direction also exhibited a proportional increase in RT. However, differential aging effects were found for preparation of extent. Elderly subjects were slower preparing short movements compared with long movements, whereas young subjects showed the opposite trend. These results suggest that with advancing age, operations concerned with movement-plan restructuring for arm and direction undergo change in processing rate, whereas operations for extent undergo more extensive alteration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

TECHNICAL AND LOCATIONAL EVOLUTION IN A HETEROGENEOUS INDUSTRY

ABSTRACT This paper uses an evolutionary simulation model of technical and locational adjustment to refine concepts of labor- and output-market segmentation within an industry. The simulation model focuses on differences among establishments arising from different strategic orientations. In particular, there are significant differences in establishments' likelihoods of relocation within a heterogeneous landscape. Empirically testable hypotheses are suggested for subsequent analyses of intraindustry evolution and local impacts.     

Influence of aging on phosphorus sorption to alum floc in lake water

Alum is often added to eutrophic lakes to limit the release of phosphorus from sediments. This study quantified the effect of age and extent of crystallization on the phosphate (PO4-P) sorption capacity of alum floc. Aluminum hydroxide flocs were formed from alum addition at a dose of 25 mg/L of Al3+ to Big Bear Lake waters returned to the laboratory; flocs were then aged for 4, 20, 50, 120, and 180 days in the treated lake waters. The physical and mineralogical properties of the alum floc were characterized using surface area and thermal analyses. Phosphate sorption to the floc was evaluated using filtered lake water and NaCl/NaHCO3 solutions spiked with PO4-P concentrations ranging from 0 to 100 mg/L. The Langmuir model provided reasonable fits to data (r2 = 0.97-1.00), from which sorption constants and sorption maxima were determined. Phosphate sorption decreased with increased floc age and crystallinity and decreased surface area. Phosphate sorption maximum of the alum floc aged for 6 months was about 50% lower than freshly precipitated floc, while the binding constant, Kads, decreased approximately 65% over this same time period.     

Integrated homology modelling and X-ray study of herpes simplex virus I thymidine kinase: a case study

Knowledge-based homology modelling together with site-directed mutagenesis, epitope and conformational mapping is an approach to predict the structures of proteins and for the rational design of new drugs. In this study we present how this procedure has been applied to model the structure of herpes simplex virus type 1 thymidine kinase (HSV1 TK, HSV1 ATP-thymidine-5'-phosphotransferase, EC 2.7.1.21). We have used, and evaluated, several secondary structure prediction methods, such as the classical one based on Chou and Fastman algorithm, neural networks using the Kabsch and Sander classification, and the PRISM method. We have validated the algorithms by applying them to the porcine adenylate kinase (ADK), whose three-dimensional structure is known and that has been used for the alignment of the TKs as well. The resulting first model of HSV1-TK consisted of the first beta-strand connected to the phosphate binding loop and its subsequent alpha-helix, the fourth beta-strand connected to the conserved FDRH sequence and two alpha-helix with basic amino acids. The 3D structure was built using the X-ray structure of ADK as template and following the general procedure for homology modelling. We extended the model by means of COMPOSER, an automatic process for protein modelling. Site-directed mutagenesis was used to experimentally verify the predicted active-site model of HSV1-TK. The data measured in our lab and by others support the suggestion that the FDRH motif is part of the active site and plays an important role in the phosphorylation of substrates. The structure of HSV1 TK, recently solved in collaboration with Prof. G. Schulz at 2.7 A resolution, includes 284 of 343 residues of the N-terminal truncated TK. The secondary structures could be clearly assigned and fitted to the density. The comparison between crystallographically determined structure and the model shows that nearly 70% of the HSV1 TK structure has been correctly modelled by the described integrated approach to knowledge based ligand protein complex structure prediction. This indicate that computer assisted methods, combined with "manual" correction both for alignment and 3D construction are useful and can be successful.     

Design aspects of bearingless slice motors

The complexity of a bearingless motor offers a multitude of freedoms in constructive design because different motor setups may have nearly the same dynamic behavior, and may differ only slightly in some operation characteristic. However, the mechanical setup often has a very strong impact on the power inverter topology and the volt-ampere requirements, thereby affecting the system costs significantly. This paper focuses on design aspects of bearingless slice motors with permanent magnet excitation, and presents a methodical evaluation approach based on performance indexes.