2,266 research outputs found

    Sleep quality influences subsequent motor skill acquisition

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    While the influence of sleep on motor memory consolidation has been extensively investigated, its relation to initial skill acquisition is less well understood. The purpose of the present study was to investigate the influence of sleep quality and quantity on subsequent motor skill acquisition in young adults without sleep disorders. Fifty-five healthy adults (mean age = 23.8 years; 34 women) wore actigraph wristbands for 4 nights, which provided data on sleep patterns before the experiment, and then returned to the laboratory to engage in a motor sequence learning task (explicit 5-item finger sequence tapping task). Indicators of sleep quality and quantity were then regressed on a measure of motor skill acquisition (Gains Within Training, GWT). Wake After Sleep Onset (WASO; i.e., the total amount of time the participants spent awake after falling asleep) was significantly and negatively related to GWT. This effect was not because of general arousal level, which was measured immediately before the motor task. Conversely, there was no relationship between GWT and sleep duration or self-reported sleep quality. These results indicate that sleep quality, as assessed by WASO and objectively measured with actigraphy before the motor task, significantly impacts motor skill acquisition in young healthy adults without sleep disorders. (PsycINFO Database Record. (c) 2016 APA, all rights reserved).Accepted manuscrip

    Using a fuzzy inference system to control a pumped storage hydro plant

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    The paper discusses the development of a fuzzy inference system (FIS) based governor control for a pumped storage hydroelectric plant. The First Hydro Company's plant at Dinorwig in North Wales is the largest of its kind in Europe and is mainly used for frequency control of the UK electrical grid. In previous investigations, a detailed model of the plant was developed using MATLAB(R)/SIMULINK(R) and this is now being used to compare FIS governor operation with the proportional-integral-derivative (PID) controller currently used. The paper describes the development of an FIS governor, and shows that its response to a step increase in load is superior to the PID under certain conditions of load. The paper proceeds to discuss the implications of these results in view of the possible practical application of an FIS governor at the Dinorwig plant

    Effect of Exercise on Reported Physical Sexual Satisfaction of University Students

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    The purpose of this study was to examine sexually active university students’ reported level of physical sexual satisfaction and perceived impact of exercise on physical satisfaction. In addition, this study investigated whether reported physical sexual satisfaction and perceived impact of exercise on physical sexual satisfaction differed based on current exercise status, body mass index, and gender. A sample of 678 college students completed a two page, 35-item survey instrument. Results indicated that students who were regular exercisers (engaged in vigorous physical activity for 20 minutes ? 3 days per week) were significantly more likely than students who were not regular exercisers to report higher levels of physical sexual satisfaction. Body mass index was also significantly correlated to physical sexual satisfaction. A series of multivariate analyses of variance revealed that physical sexual satisfaction and perceived impact of exercise on physical sexual satisfaction differed significantly based on gender. Overall, students perceived body image, sexual desirability perception, and physical strength as the three leading components of physical sexual satisfaction impacted by exercise. Since regular exercise may increase physical sexual satisfaction levels, health professionals could use the results of this study to help motivate individuals to enhance their physical sexual satisfaction by becoming more physically active

    Diffusive and convective transfer of cytokine-inducing bacterial products across hemodialysis membranes

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    Diffusive and convective transfer of cytokine-inducing bacterial products across hemodialysis membranes. The widespread use of bicarbonate dialysate, and high-flux and high-efficiency dialyzers have raised concerns regarding the transmembrane passage of bacterial products from the dialysate into the blood compartment. To study the mechanisms as well as magnitude of the transmembrane transfer of bacterial products from the dialysate, we developed a computerized in vitro dialysis model which provides continuous pressure recording from the arterial, venous, dialysate inflow and outflow ports. By virtue of a computer controlled on-line infusion pump, this model permits control of ultrafiltration/backfiltration. Heparinized (10 U/ml) whole blood (150 ml) was circulated through the blood compartment for 120 minutes at 100ml/min. Bicarbonate dialysate contaminated with Pseudomonas maltophilia filtrate was circulated through the dialysate compartment at 100ml/min. A two-point pressure of +10mm of Hg (ultrafiltration) was maintained for the first 60 minutes and -10mm of Hg (backfiltration) for the next 60 minutes. Whole blood samples (10 ml) were drawn from the blood at 0, 60 and 120 minutes. Peripheral blood mononuclear cells (PBMC) harvested from these samples were incubated for 24 hours in tissue culture medium. In addition, 0.5ml samples of dialysate were collected at 0, 60 and 120 minutes and incubated with PBMC from the same donor for 24 hours. After 24 hour incubation, total cell-associated IL-1Ra and IL-1β were measured by specific radioimmunoassay. Paired experiments were performed with eight high-flux synthetic membranes (polyamide) and eight low-flux cellulose membranes (hemophan). Cytokine production is expressed as pg/2.5 million PBMC. During the mandatory ultrafiltration phase of the experiment (first hour), the production of IL-1Ra by PBMC from the blood compartment rose from 515 ± 118 to 785 ± 209 with polyamide membranes, and from 1175 ± 365 to 3865 ± 1847 with hemophan membranes, suggesting diffusive transport of bacterial products across the membrane. In contrast, at the end of the backfiltration phase (second hour), there was no further rise in the production of IL-1Ra by PBMC from the blood compartment (702 ± 123 with polyamide, and 2284 ± 886 with hemophan). The production of IL-1Ra by PBMC harvested from the blood compartment of polyamide membranes at 0, 60 and 120 minutes was lower than that with hemophan membranes (P = 0.01). In contrast to IL-1Ra, the production of IL-1β by PBMC harvested from the blood compartment with both membranes was uniformly low. The results of this study demonstrate the diffusive transfer of bacterial products across dialysis membranes. Therefore, any condition that increases diffusive transport such as dialyzers with large surface areas and high blood and dialysate flow rates could potentially increase the reverse transfer of bacterial products from the dialysate. This risk is not greater for synthetic high-flux membranes such as polyamide. Further, IL-1β is a less sensitive indicator than IL-1Ra of the transmembrane passage of cytokine-inducing substances from the dialysate to blood compartment

    Origin of ferroelectricity in the multiferroic barium fluorides BaMF4

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    We present a first principles study of the series of multiferroic barium fluorides with the composition BaMF4, where M is Mn, Fe, Co, or Ni. We discuss trends in the structural, electronic, and magnetic properties, and we show that the ferroelectricity in these systems results from the "freezing in" of a single unstable polar phonon mode. In contrast to the case of the standard perovskite ferroelectrics, this structural distortion is not accompanied by charge transfer between cations and anions. Thus, the ferroelectric instability in the multiferroic barium fluorides arises solely due to size effects and the special geometrical constraints of the underlying crystal structure.Comment: 8 pages, 6 figures, 3 table

    Algorithmic Bias in Machine Learning Based Delirium Prediction

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    Although prediction models for delirium, a commonly occurring condition during general hospitalization or post-surgery, have not gained huge popularity, their algorithmic bias evaluation is crucial due to the existing association between social determinants of health and delirium risk. In this context, using MIMIC-III and another academic hospital dataset, we present some initial experimental evidence showing how sociodemographic features such as sex and race can impact the model performance across subgroups. With this work, our intent is to initiate a discussion about the intersectionality effects of old age, race and socioeconomic factors on the early-stage detection and prevention of delirium using ML.Comment: Extended Abstract presented at Machine Learning for Health (ML4H) symposium 2022, November 28th, 2022, New Orleans, United States & Virtual, http://www.ml4h.cc, 14 page

    Timing of transcranial direct current stimulation at M1 does not affect motor sequence learning

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    Administering anodal transcranial direct current stimulation (tDCS) at the primary motor cortex (M1) at various temporal loci relative to motor training is reported to affect subsequent performance gains. Stimulation administered in conjunction with motor training appears to offer the most robust benefit that emerges during offline epochs. This conclusion is made, however, based on between-experiment comparisons that involved varied methodologies. The present experiment addressed this shortcoming by administering the same 15-minute dose of anodal tDCS at M1 before, during, or after practice of a serial reaction time task (SRTT). It was anticipated that exogenous stimulation during practice with a novel SRTT would facilitate offline gains. Ninety participants were randomly assigned to one of four groups: tDCS before practice, tDCS during practice, tDCS after practice, or no tDCS. Each participant was exposed to 15 min of 2 mA of tDCS and motor training of an eight-element SRTT. The anode was placed at the right M1 with the cathode at the left M1, and the left hand was used to execute the SRTT. Test blocks were administered 1 and 24 h after practice concluded. The results revealed significant offline gain for all conditions at the 1-hour and 24-hour test blocks. Importantly, exposure to anodal tDCS at M1 at any point before, during, or after motor training failed to change the trajectory of skill development as compared to the no-stimulation control condition. These data add to the growing body of evidence questioning the efficacy of a single bout of exogenous stimulation as an adjunct to motor training for fostering skill learning.</p

    Towards a microscopic theory of toroidal moments in bulk periodic crystals

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    We present a theoretical analysis of magnetic toroidal moments in periodic systems, in the limit in which the toroidal moments are caused by a time and space reversal symmetry breaking arrangement of localized magnetic dipole moments. We summarize the basic definitions for finite systems and address the question of how to generalize these definitions to the bulk periodic case. We define the toroidization as the toroidal moment per unit cell volume, and we show that periodic boundary conditions lead to a multivaluedness of the toroidization, which suggests that only differences in toroidization are meaningful observable quantities. Our analysis bears strong analogy to the modern theory of electric polarization in bulk periodic systems, but we also point out some important differences between the two cases. We then discuss the instructive example of a one-dimensional chain of magnetic moments, and we show how to properly calculate changes of the toroidization for this system. Finally, we evaluate and discuss the toroidization (in the local dipole limit) of four important example materials: BaNiF_4, LiCoPO_4, GaFeO_3, and BiFeO_3.Comment: replaced with final (published) version, which includes some changes in the text to improve the clarity of presentatio
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