1,135 research outputs found
Short-term memory effects of an auditory biofeedback on isometric force control: Is there a differential effect as a function of transition trials?
The aim of the present study was to investigate memory effects, force
accuracy, and variability during constant isometric force at different force
levels, using auditory biofeedback. Two types of transition trials were used: a
biofeedback-no biofeedback transition trial and a no biofeedback-biofeedback
transition trial. The auditory biofeedback produced a low- or high-pitched
sound when participants produced an isometric force lower or higher than
required, respectively. To achieve this goal, 16 participants were asked to
produce and maintain two different isometric forces (305% and 90N5%)
during 25s. Constant error and standard deviation of the isometric force were
calculated. While accuracy and variability of the isometric force varied
according to the transition trial, a drift of the force appeared in the no
biofeedback condition. This result suggested that the degradation of
information about force output in the no biofeedback condition was provided by
a leaky memory buffer which was mainly dependent on the sense of effort.
Because this drift remained constant whatever the transition used, this memory
buffer seemed to be independent of short-term memory processes.Comment: Human Movement Science (2011) epub ahead of prin
Chemo-mechanical couplings in compacted argillite submitted to high-pH environment
AbstractIn the French concept of deep nuclear wastes repository, the galleries should be backfilled with excavated argillite after the site exploitation period. After several thousands of years, the degradation of the concrete lining of the galleries will generate alkaline fluid (pH > 12) that will diffuse through the backfill. The objective of the paper is to describe the influence of such solute diffusion on the microstructure and the mechanical behavior of compacted argillite. Saturated-portlandite water was circulated through compacted samples for 3, 6 and 12months at 20 °C or 60 °C, respectively. The microstructures before and after fluid circulation were determined with mercury intrusion porosimetry. Since it was planned to introduce additives (bentonite or lime) in the remoulded argillite to backfill the deep galleries, such mixtures were also studied. The results show that the influence of the alkaline fluid on the properties of the argillite is a function of the nature of the additive. The pure argillite undergoes slight modifications that can be related to a limited dissolution of its clayey particles. Conversely, intense alteration of the bentonite-argillite mixture was observed. Lime addition improves the mechanical characteristics of the argillite through the precipitation of cementitious compounds
Planetary nebulae in the inner Milky Way
New abundances of planetary nebulae located towards the bulge of the Galaxy
are derived based on observations made at LNA (Brazil). We present accurate
abundances of the elements He, N, S, O, Ar, and Ne for 56 PNe located towards
the galactic bulge. The data shows a good agreement with other results in the
literature, in the sense that the distribution of the abundances is similar to
those works. From the statistical analysis performed, we can suggest a
bulge-disk interface at 2.2 kpc for the intermediate mass population, marking
therefore the outer border of the bulge and inner border of the disk.Comment: 2 pages, 1 figure, uses iaus.cls, in press, IAU Symp. 265, Chemical
abundances in the Universe: Connecting the first Stars to Planets, Ed. K.
Cunha, M. Spite, B. Barbu
Strategies for Predicting and Treating Access Induced Ischemic Steal Syndrome
Access induced ischemia is an uncommon but devastating complication for patients maintained on hemodialysis. A number of clinical risk factors have been identified to select patients at risk. Intraoperative measurement of the digital–brachial index may further distinguish at-risk patients when the DBI is <0.45. Once clinically significant steal has developed, surgical strategies to treat this problem should ideally reverse the ischemia while maintaining uninterrupted access for hemodialysis. To date, the distal revascularization–interval ligation or DRIL procedure has been the most consistently successful tactic in achieving these dual objectives. A number of alternative strategies have recently been proposed and will be discussed
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