323 research outputs found
Learning Democracy through Self-governance: The Case of Housing Co-operative
Housing co-operatives are a unique site to learn democracy through participation in self-governance by volunteering on boards and committees. Members reported both nonformal and informal learning; the latter was particularly significant for the development of skills, knowledge, attitudes and values required for effective democratic participation
A Randomised, Placebo-Controlled, Crossover Study Investigating the Effects of Nicotine Gum on Strength, Power and Anaerobic Performance in Nicotine-Naïve, Active Males
The influence of negative-energy states on proton-proton bremsstrahlung
We investigate the effect of negative-energy states on proton-proton
bremsstrahlung using a manifestly covariant amplitude based on a T-matrix
constructed in a spectator model. We show that there is a large cancellation
among the zeroth-order, single- and double-scattering diagrams involving
negative-energy nucleonic currents. We thus conclude that it is essential to
include all these diagrams when studying effects of negative-energy states.Comment: 12 pages revtex and 3 figure
Ammonium chloride ingestion attenuates exercise-induced mRNA levels in human muscle
Minimizing the decrease in intracellular pH during high-intensity exercise training promotes greater improvements in mitochondrial respiration. This raises the intriguing hypothesis that pH may affect the exercise-induced transcription of genes that regulate mitochondrial biogenesis. Eight males performed 10x2-min cycle intervals at 80% VO2speak intensity on two occasions separated by ~2 weeks. Participants ingested either ammonium chloride (ACID) or calcium carbonate (PLA) the day before and on the day of the exercise trial in a randomized, counterbalanced order, using a crossover design. Biopsies were taken from the vastus lateralis muscle before and after exercise. The mRNA level of peroxisome proliferator-activated receptor co-activator 1α (PGC-1α), citrate synthase, cytochome c and FOXO1 was elevated at rest following ACID (P<0.05). During the PLA condition, the mRNA content of mitochondrial- and glucose-regulating proteins was elevated immediately following exercise (P<0.05). In the early phase (0-2 h) of post-exercise recovery during ACID, PGC-1α, citrate synthase, cytochome C, FOXO1, GLUT4, and HKII mRNA levels were not different from resting levels (P>0.05); the difference in PGC-1α mRNA content 2 h post-exercise between ACID and PLA was not significant (P = 0.08). Thus, metabolic acidosis abolished the early post-exercise increase of PGC-1α mRNA and the mRNA of downstream mitochondrial and glucose-regulating proteins. These findings indicate that metabolic acidosis may affect mitochondrial biogenesis, with divergent responses in resting and post-exercise skeletal muscle
Safflower, Carthamus tinctorius L.
Safflower is one of humanity's oldest crops but it generally has been grown on small plots for domestic use and remains a minor crop with a world seed production of about 800 000 t per year. This monograph overviews existing knowledge of the genus with emphasis on genetic resources. Chapters cover the following topics: taxonomy, nomenclature, centres of diversity, botany, production, genetics, uses, breeding, research priorities and constraints, collecting, and evaluation. Information on institutions holding safflower collections and undertaking research is also included. (Abstract © CAB ABSTRACTS, CAB International
Autonomic cardiovascular response to acute hypoxia and passive head-up tilting in humans
Acute hypoxia may alter autonomic cardiovascular reflexes during orthostasis. Heart rate variability (HRV), arterial blood pressure (MAP), and respiratory sinus arrhythmia (RSA) were recorded during supine (SUP) and passive head up tilt (HUT) in eight healthy humans, spontaneously breathing either room air or 10 % O2 in N2. In the time domain, heart rate increased and variability decreased with HUT in both trials, with no difference between trials. In the frequency domain, normalized low frequency HRV increased, and normalized high frequency HRV decreased with HUT in both trials, with no difference between trials. MAP was 74.9 (8.6) and 77.5 (11.7) mmHg when SUP in the room air and hypoxia trials, respectively. A significant increase in MAP occurred with HUT in the room air trial but not in the hypoxia trial. In both trials, end tidal CO2 decreased with HUT, with no difference between trials. In the room air trial, end tidal O2 increased with HUT, whereas during the hypoxia trial, end tidal O2 decreased with HUT. The distribution of heart beats relative to the phase of ventilation (%HB IN and %HBOUT) was similar in both trials: the %HB IN was 43.5 (3.3) % and %HBOUT was 56.5 (4.2) % breathing room air when SUP, and 45.5 (3.0) and 54.5 (3.2) when hypoxic and SUP. For both trials, this distribution did not change with HUT. As both HRV and RSA showed similar responses to HUT when spontaneously breathing either room air or 10 % O2 in N2, we suggest that autonomic cardiovascular reflexes are preserved during acute hypoxia. © 2013 Springer-Verlag Berlin Heidelberg
Nicotine Supplementation Does Not Influence Performance of a 1h Cycling Time-Trial in Trained Males
The use of nicotine amongst professional and elite athletes is high, with anecdotal evidence indicating increased prevalence amongst cycling sports. However, previous investigations into its effects on performance have not used high-validity or -reliability protocols nor trained cyclists. Therefore, the present study determined whether nicotine administration proved ergogenic during a ∼1 h self-paced cycling time-trial (TT). Ten well-trained male cyclists (34 ± 9 years; 71 ± 8 kg; O2max: 71 ± 6 ml ⋅ kg−1 ⋅ min−1) completed three work-dependent TT following ∼30 min administration of 2 mg nicotine gum (GUM), ∼10 h administration of 7 mg ⋅ 24 h−1 nicotine patch (PAT) or color- and flavor-matched placebos (PLA) in a randomized, crossover, and double blind design. Measures of nicotine’s primary metabolite (cotinine), core body temperature, heart rate, blood biochemistry (pH, HCO3−, La−) and Borg’s rating of perceived exertion (RPE) accompanied performance measures of time and power output. Plasma concentrations of cotinine were highest for PAT, followed by GUM, then PLA, respectively (p < 0.01). GUM and PAT resulted in no significant improvement in performance time compared to PLA (62.9 ± 4.1 min, 62.6 ± 4.5 min, and 63.3 ± 4.1 min, respectively; p = 0.73), with mean power outputs of 264 ± 31, 265 ± 32, and 263 ± 33 W, respectively (p = 0.74). Core body temperature was similar between trials (p = 0.33) whilst HR averaged 170 ± 10, 170 ± 11, and 171 ± 11 beats ⋅ min−1 (p = 0.60) for GUM, PAT, and PLA, respectively. There were no differences between trials for any blood biochemistry (all p > 0.46) or RPE with mean values of 16.7 ± 0.9, 16.8 ± 0.7, and 16.8 ± 0.8 (p = 0.89) for GUM, PAT, and PLA, respectively. In conclusion: (i) nicotine administration, whether via gum or transdermal patch, did not exert an ergogenic or ergolytic effect on self-paced cycling performance of ∼1 h; (ii) systemic delivery of nicotine was greatest when using a transdermal patch; and (iii) nicotine administration did not alter any of the psycho-physiological measures observed
The Efficacy of Ingesting Water on Thermoregulatory Responses and Running Performance in a Warm-Humid Condition
The understanding that fluid ingestion attenuates thermoregulatory and circulatory stress during exercise in the heat was based on studies conducted in relatively dry (∼50% RH) environments. It remains undetermined whether similar effects occur during exercise in a warm and more humid environment, where evaporative capacity is reduced. Nine well-trained, unacclimatised male runners were randomly assigned to perform four experimental trials where they ran for 60 min at an intensity of 70% VO2max followed by an incremental exercise test until volitional exhaustion. The four trials consisted of non-fluid ingestion (NF) and fluid ingestion (FI) in a warm-dry (WD) and warm-humid condition (WH). Time to exhaustion (TTE), body temperature (Tb), whole body sweat rate, partitional calorimetry measures, heart rate and plasma volume were recorded during exercise. There was no significant difference in Tb following 60 min of exercise in FI and NF trial within both WD (37.3°C ± 0.4 vs. 37.4°C ± 0.3; p > 0.05) and WH conditions (38.0°C ± 0.4 vs. 38.1°C ± 0.4; p > 0.05). The TTE was similar between FI and NF trials in both WH and WD, whereas exercise capacity was significantly shorter in WH than WD (9.1 ± 2.8 min vs. 12.7 ± 2.4 min, respectively; p = 0.01). Fluid ingestion failed to provide any ergogenic benefit in attenuating thermoregulatory and circulatory stress during exercise in the WH and WD conditions. Consequently, exercise performance was not enhanced with fluid ingestion in the warm-humid condition, although the humid environment detrimentally affected exercise endurance
A Preliminary Investigation on Smokeless Tobacco Use and Its Cognitive Effects Among Athletes
The Supplementary Material for this article can be found
online at: https://www.frontiersin.org/articles/10.3389/fphar.
2018.00216/full#supplementary-materialIntroduction: Among athletes, an increasing use of nicotine via smokeless tobacco has
been reported. However, there are currently unanswered questions about whether the
use by athletes is due to nicotine’s addictive properties and/or to benefits in physical and
cognitive performance (e.g., decision-making). In this original article we reported about,
(i) snus-induced reinforcing effects among snus-user athletes (Survey) and (ii) the effects
of snus on the Iowa Gambling Task (IGT) in snus-user skiers (Experimental study). IGT is
an experimental neuropsychological task that has been previously used on athletes and
addicts to test decision-making.
Methods: Survey: data were collected with the modified Cigarette Evaluation
Questionnaire (mCEQ) that was administered to 61 winter sport athlete snus-users
in Northern Italy. Experimental study: IGT data included: amount of money earned,
number of choices from advantageous and disadvantageous decks and overall net
score. Eighteen male snus-users were tested under satiety or after 12-h abstinence
conditions according to a crossover design.
Results: Survey: the comparison between occasional vs. regular snus-users showed
a statistically significant difference in satisfaction (P = 0.0088), calm (P = 0.0252),
and enjoyment (P = 0.0001) mCEQ items suggesting a snus intake/effect relationship.
Experimental study: significantly higher IGT net scores were found during the first 20
choice cards after abstinence vs. satiety conditions (P = 0.0024).
Conclusion: In the Survey, regular snus use induces greater satisfaction and
psychological reward than occasional use. In the Experimental study, snus intake might
produce an early and transient cognitive improvement on IGT in abstinent snus-users,
presumably acting as a withdrawal relief
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