Sökresultat

Filtyp

Din sökning på "*" gav 542701 sökträffar

The wholeness of a cybernetican

It is our impression that Gordon Pask’s writings cover fundamentals for large parts of the widely expanding fields of Cybernetics and Systems Theory. Thereby, and by his lecturing activities, he has become a unique figure in maintaining a kind of unity of the field of Cybernetics, well in accord with Wiener’s view (“control and communication in the animal and the machine”; cf[26]). And that, with

On Millian Discontinuities

Suppose one sets up a sequence of less-and-less valuable objects such that each object in the sequence is only marginally worse than its immediate predecessor. Could one in this way arrive at something that is dramatically inferior to the point of departure? It has been claimed that if there is a radical value difference between the objects at each end of the sequence, then at some point there mus

Long-term rAAV-mediated gene transfer of GDNF in the rat Parkinson's model: intrastriatal but not intranigral transduction promotes functional regeneration in the lesioned nigrostriatal system

Previous studies have used recombinant adeno-associated viral (rAAV) vectors to deliver glial cell line-derived neurotrophic factor (GDNF) in the substantia nigra to protect the nigral dopamine (DA) neurons from 6-hydroxydopamine-induced damage. However, no regeneration or functional recovery was observed in these experiments. Here, we have used an rAAV-GDNF vector to express GDNF long-term (6 mon

Decreased levels of ionized calcium one year after hemithyroidectomy: importance of reduced thyroid hormones

BACKGROUND: Previously we have found reduced levels of total serum calcium and 1,25(OH)2D3 despite an unaltered stimulated parathyroid hormone (PTH) secretion 1 year after hemithyroidectomy. The present study was undertaken to elucidate the possible relationship between calcium homeostasis, thyroid hormones and bone resorption in a group of 45 consecutive patients subjected to hemithyroidectomy be

Protein folding in the absence of a clear free-energy barrier

Many small proteins fold in a two-state manner, the rate-limiting step being the passage of the free-energy barrier separating the unfolded state from the native one. The free-energy barrier is, however, weak or absent for the fastest-folding proteins. Here a simple diffusion picture for such proteins is discussed. It is tested on a model protein that makes a three-helix bundle. Assuming the motio

Physical and Chemical Characterisation of Potassium Deactivation of an SCR Catalyst for Biomass Combustion

The deactivation of a commercial Selective Catalytic Reduction (SCR) catalyst, of V2O5−WO3/TiO2 type, has been studied through comparisons with results from a full-scale biomass combustion plant to that with laboratory experiments. In the latter, the catalyst was exposed to KCl and K2SO4 by both wet impregnation with diluted salt solutions and deposition of generated submicrometer aerosol particle

Environmental influence on recovery after brain lesions--experimental and clinical data.

One aim of rehabilitation after brain lesions should be to optimise the function of the remaining intact brain. Experimental studies on focal cerebral infarcts in the rat have demonstrated that postischemic environmental enrichment significantly improves functional outcome, increases dendrite branching and number of dendritic spines in the contralateral cortex, influences expression of many genes

Tire Modeling and Friction Estimation

New system technologies are continuously improving the performance of vehicles regarding comfort, stability, environmental stresses, and safety. Novel sensors are developed and used together with advanced control algorithms and faster and more accurate actuators to help the driver to maneuver the vehicle in a safer way. The physical traction limit set by the friction between the tires and the road

Hormone-sensitive lipase in skeletal muscle: regulatory mechanisms.

AIM: The enzymatic regulation of intramuscular triacylglycerol (TG) breakdown has until recently not been well understood. Our aim was to elucidate the role of hormone-sensitive lipase (HSL), which controls TG breakdown in adipose tissue. METHODS: Isolated rat muscle as well as exercising humans were studied. RESULTS: The presence of HSL was demonstrated in all muscle fibre types by Western blotti

Changes of cellulose fiber wall structure during drying investigated using NMR self-diffusion and relaxation experiments

The self-diffusion of water sorbed in cellulose fibers was investigated by means of NMR during slow drying in order to follow changes in the cellulose porous structure. In pulp fibers pores with at least one dimension on the mum scale were observed at high amounts of sorbed water and nm-scale pores at low amounts. Beating affected the mum-scale pores. Regenerated cellulose fibers had nm-scale pore

Physical housing environment: development of a self-assessment instrument

The aims of this study were to construct and develop a self-administered assessment instrument, useful for studying clients' own perception of accessibility and usability in their housing environment, and to test the instrument for reliability. It was developed for use in combination with an objective, norm-based assessment of the physical housing environment, the Enabler instrument. The instrumen

Fogar i träfönster : förstudie

Studien utgör underlag till en konstruktionslära för fogar i fönster. I rapporten pekas på problem med att upprätthålla fuktbalans i fönsterträ då fukt kapillärt sugs in via konstruktionens diskontinuiteter. Inledande försök beskrivs liksom förslag till åtgärder i befintliga fönster.

Was southern Sweden ice free at 19-25 ka, or were the post LGM glacifluvial sediments incompletely bleached?

Glacifluvial deposits along an ice-marginal zone,in Smaland, southern Sweden, have been dated using post-IR blue OSL. To test for incomplete bleaching, we adopted two strategies: analysis of modern analogues and small-aliquot dose distributions. Samples of modern fluvial sediments show no significant incomplete bleaching; they yield equivalent doses of only 0.5-2 Gy (similar to 0.25-4% of our glac