1,196 research outputs found
Diurnal influences of fasted and non-fasted brisk walking on gastric emptying rate, metabolic responses, and appetite in healthy males
Growing evidence suggests circadian rhythms, nutrition and metabolism are intimately linked. Intermittent fasting (IMF) has become an increasingly popular intervention for metabolic health and combining IMF with exercise may lead to benefits for weight management. However, little is known about the diurnal variation of fasted exercise. This study aimed to investigate the diurnal influences on gastric emptying rate (GER), metabolic responses, and appetite to fasted and non-fasted exercise. Twelve healthy males completed four 45 min walks in a randomised order. Walks were completed in the morning (AM) and evening (PM) and either fasted (FASTED) or after consumption of a standardised meal (FED). GER of a semi-solid lunch was subsequently measured for 2 h using the 13C breath test. Blood glucose concentration, substrate utilisation, and ratings of appetite were measured throughout. Energy intake was also assessed for the following 24 h. GER Tlag was slower in PM-FASTED compared to AM-FASTED, AM-FED, and PM-FED (75 ± 18 min vs. 63 ± 14 min, P = 0.001, vs. 65 ± 10 min, P = 0.028 and vs. 67 ± 16 min, P = 0.007). Blood glucose concentration was greater in the FED trials in comparison to the FASTED trials pre-lunch (P  0.05) or 24 h post-energy intake (P = 0.476). These findings suggest that evening fasted exercise results in delayed GER, without changes in appetite. No compensatory effects were observed for appetite, and 24 h post-energy intake for both fasted exercise trials, therefore, increased fat oxidation holds positive implications for weight management
The effect of brisk walking in the fasted versus fed state on metabolic responses, gastrointestinal function, and appetite in healthy men
Objective
To investigate the effect of brisk walking in the fasted versus fed state on gastric emptying rate (GER), metabolic responses and appetite hormone responses.
Subjects/methods
Twelve healthy men completed two 45 min treadmill walks, fasted (FASTED) and followed consumption of a standardised breakfast (FED). GER of a standardised lunch was subsequently measured for 2 h using the 13C-breath test method. Blood samples were collected at baseline, post-breakfast period, pre-exercise, immediately post exercise, pre-lunch then every 30 min following lunch for 2 h. Circulating concentrations of acylated ghrelin (GHR), glucagon-like peptide-1 (GLP-1), peptide tyrosine tyrosine (PYY), pancreatic polypeptide (PP), glucose, insulin, triglycerides, non-esterified fatty acids (NEFA) and cholesterol were measured. Subjective feelings of appetite were assessed at 15 min intervals throughout. Substrate utilisation was measured every 30 min, and continuously throughout exercise by indirect calorimetry.
Results
No differences were observed for GER T½ (FASTED 89 ± 22 vs. FED 89 ± 24 min, P = 0.868) nor Tlag (FASTED 55 ± 15 vs. FED 54 ± 14 min, P = 0.704). NEFA concentrations were higher in FASTED at pre-exercise, post exercise and 30 min post exercise (pre-lunch) (all P < 0.05) but no differences were observed for glucose, cholesterol or triglycerides. Carbohydrate oxidation was greater at all time-points during FED exercise (all P < 0.05). Minimal changes in appetite were observed post lunch ingestion with no differences in PYY or GHR observed between trials. GLP-1 concentrations were greater in FED post-breakfast and pre-exercise (P < 0.05), though no differences were observed after lunch. A greater concentration of PP was observed in FED from pre-exercise to 30 min post lunch consumption (all P < 0.05). Insulin concentrations were higher in FED pre-exercise but higher in FASTED 1.5 h post lunch (P < 0.05).
Conclusion
These findings suggest that gastrointestinal function, hunger and appetite regulatory hormones are not sensitive to low-intensity bouts of physical activity and holds positive implications for weight management practices
The effect of exercise intensity on gastric emptying rate, appetite and gut derived hormone responses after consuming a standardised semi-solid meal in healthy males
This study investigated the acute circulating gut hormone, appetite and gastric emptying rate responses to a semi-solid meal following exercise at different intensities. Twelve men completed three trials in a randomised-crossover design, consisting of continuous cycling at 70% VË™
O2Peak (HIGH), 40% VË™
O2Peak (LOW) or rest (CONTROL). Baseline samples were collected after an overnight fast before undertaking the 60 min exercise or rest period, followed by 30 min rest before consumption of a standardised semi-solid meal (~242 kcal). During the 2 h postprandial period, gastric emptying rate of the meal was examined using the 13C-breath test method, appetite was measured using visual analogue scales, and serum concentrations of acylated ghrelin, pancreatic polypeptide, peptide YY, glucagon-like peptide-1, insulin, glucose, triglycerides, total cholesterol and non-esterified fatty acids were assessed. Subjective appetite response was not different between trials (p > 0.05). Half emptying time of the meal was 89 ± 13, 82 ± 8 and 94 ± 31 min on CONTROL, LOW and HIGH, respectively (p = 0.247). In healthy un-trained adult males, responses to exercise at intensities of 70% and 40% V˙
O2Peak did not differ to a non-exercise control for measurements of subsequent gastric emptying, circulating gut hormone response or appetite. These results suggest that exercise intensity has little effect on post-exercise appetite response to a semi-solid meal
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Heat transfer and flow stability in a rotating disk/stagnation flow chemical vapor deposition reactor
The flow and heat transfer in a vertical high-speed rotating disk/stagnation flow chemical vapor deposition (CVD) reactor is studied with particular emphasis on the effects of the spacing, {bar H}, between the stationary gas inlet and the rotating disk. A one-dimensional analysis is used to determine the effects of {bar H}, flow rate, and disk spin rate on the gas flow patterns and the heat transfer from the disk; the effects of buoyancy, reactor side walls, and finite disk geometry on these quantities are determined in a two-dimensional analysis. The Navier-Stokes and energy equations are solved for hydrogen over a range of gas flow rates, disk spin rates, axial and radial aspect ratios, for a pressure of 250 Torr, inlet gas temperature of 50 C, and disk temperature of 800 C. The 1D similarity solution results show that the dimensionless heat transfer from the rotating disk, Nu{sub 1D}, depends on SP and Re{sub w} to a much greater extent at smaller spacings than at larger spacings. For SP values of 0.92 and 4.5 and for both spacings studied, Nu{sub 1D} approaches the value for an infinite rotating disk for Re{sub w} {approx} 450, except for the case at SP = 4.5 and A = 0.54 where Nu{sub 1D} is significantly larger. The 1D results also show that for small SP (0.23) there is a significant flow toward r = 0 (the radial component of velocity is negative) which is larger for the smaller value of A. The 2D results show that the effect of inlet velocity (SP) on the radial variation of the disk heat transfer (Nu{sub 2D}) is greater for larger values of A; for both values of A there is greater radial variation of Nu{sub 2D} at the laser value of SP
Density functional theory of phase coexistence in weakly polydisperse fluids
The recently proposed universal relations between the moments of the
polydispersity distributions of a phase-separated weakly polydisperse system
are analyzed in detail using the numerical results obtained by solving a simple
density functional theory of a polydisperse fluid. It is shown that universal
properties are the exception rather than the rule.Comment: 10 pages, 2 figures, to appear in PR
Bolus ingestion of whey protein immediately post-exercise does not influence rehydration compared to energy-matched carbohydrate ingestion
Whey protein is a commonly ingested nutritional supplement amongst athletes and regular exercisers; however, its role in post-exercise rehydration remains unclear. Eight healthy male and female participants completed two experimental trials involving the ingestion of 35 g of whey protein (WP) or maltodextrin (MD) at the onset of a rehydration period, followed by ingestion of water to a volume equivalent to 150% of the amount of body mass lost during exercise in the heat. The gastric emptying rates of the solutions were measured using 13C breath tests. Recovery was monitored for a further 3 h by the collection of blood and urine samples. The time taken to empty half of the initial solution (T1/2) was different between the trials (WP = 65.5 ± 11.4 min; MD = 56.7 ± 6.3 min; p = 0.05); however, there was no difference in cumulative urine volume throughout the recovery period (WP = 1306 ± 306 mL; MD = 1428 ± 443 mL; p = 0.314). Participants returned to net negative fluid balance 2 h after the recovery period with MD and 3 h with WP. The results of this study suggest that whey protein empties from the stomach at a slower rate than MD; however, this does not seem to exert any positive or negative effects on the maintenance of fluid balance in the post-exercise period
Corrections to the Central Limit Theorem for Heavy-Tailed Probability Densities
Classical Edgeworth expansions provide asymptotic correction terms to the
Central Limit Theorem (CLT) up to an order that depends on the number of
moments available. In this paper, we provide subsequent correction terms beyond
those given by a standard Edgeworth expansion in the general case of regularly
varying distributions with diverging moments (beyond the second). The
subsequent terms can be expressed in a simple closed form in terms of certain
special functions (Dawson's integral and parabolic cylinder functions), and
there are qualitative differences depending on whether the number of moments
available is even, odd or not an integer, and whether the distributions are
symmetric or not. If the increments have an even number of moments, then
additional logarithmic corrections must also be incorporated in the expansion
parameter. An interesting feature of our correction terms for the CLT is that
they become dominant outside the central region and blend naturally with known
large-deviation asymptotics when these are applied formally to the spatial
scales of the CLT
Interacting Random Walkers and Non-Equilibrium Fluctuations
We introduce a model of interacting Random Walk, whose hopping amplitude
depends on the number of walkers/particles on the link. The mesoscopic
counterpart of such a microscopic dynamics is a diffusing system whose
diffusivity depends on the particle density. A non-equilibrium stationary flux
can be induced by suitable boundary conditions, and we show indeed that it is
mesoscopically described by a Fourier equation with a density dependent
diffusivity. A simple mean-field description predicts a critical diffusivity if
the hopping amplitude vanishes for a certain walker density. Actually, we
evidence that, even if the density equals this pseudo-critical value, the
system does not present any criticality but only a dynamical slowing down. This
property is confirmed by the fact that, in spite of interaction, the particle
distribution at equilibrium is simply described in terms of a product of
Poissonians. For mesoscopic systems with a stationary flux, a very effect of
interaction among particles consists in the amplification of fluctuations,
which is especially relevant close to the pseudo-critical density. This agrees
with analogous results obtained for Ising models, clarifying that larger
fluctuations are induced by the dynamical slowing down and not by a genuine
criticality. The consistency of this amplification effect with altered coloured
noise in time series is also proved.Comment: 8 pages, 7 figure
Shipping in the north-east Atlantic : identifying spatial and temporal patterns of change
This work was supported by a faculty PhD bursary from the University of Portsmouth. Work was supported by the Marine Ecosystems Research Programme.Maritime traffic is increasing globally, with a four-fold increase in commercial vessel movements between 1992 and 2012. Vessels contribute to noise and air pollution, provide pathways for non-native species, and collide with marine wildlife. While knowledge of shipping trends and potential environmental impacts exists at both local and global levels, key information on vessel density for regional-scale management is lacking. This study presents the first in-depth spatio-temporal analysis of shipping in the north-east Atlantic region, over three years in a five-year period. Densities increased by 34%, including in 73% of Marine Protected Areas. Western Scotland and the Bay of Biscay experienced the largest increases in vessel density, predominantly from small and slow vessels. Given well-documented impacts that shipping can have on the marine environment, it is crucial that this situation continues to be monitored – particularly in areas designated to protect vulnerable species and ecosystems which may already be under pressure.Publisher PDFPeer reviewe
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