Sleep quantity and quality during heat-based training and the effects of cold-water immersion recovery

- Introduction Heat-based training (HT) is becoming increasingly popular as a means of inducing acclimation before athletic competition in hot conditions and/or to augment the training impulse beyond that achieved in thermo-neutral conditions. Importantly, current understanding of the effects of HT on regenerative processes such as sleep and the interactions with common recovery interventions remain unknown. This study aimed to examine sleep characteristics during five consecutive days of training in the heat with the inclusion of cold-water immersion (CWI) compared to baseline sleep patterns. - Methods Thirty recreationally-trained males completed HT in 32 ± 1 °C and 60% rh for five consecutive days. Conditions included: 1) 90 min cycling at 40 % power at VO2max (Pmax) (90CONT; n = 10); 90 min cycling at 40 % Pmax with a 20 min CWI (14 ± 1 °C; 90CWI; n = 10); and 30 min cycling alternating between 40 and 70 % Pmax every 3 min, with no recovery intervention (30HIT; n = 10). Sleep quality and quantity was assessed during HT and four nights of 'baseline' sleep (BASE). Actigraphy provided measures of time in and out of bed, sleep latency, efficiency, total time in bed and total time asleep, wake after sleep onset, number of awakenings, and wakening duration. Subjective ratings of sleep were also recorded using a 1-5 Likert scale. Repeated measures analysis of variance (ANOVA) was completed to determine effect of time and condition on sleep quality and quantity. Cohen's d effect sizes were also applied to determine magnitude and trends in the data. - Results Sleep latency, efficiency, total time in bed and number of awakenings were not significantly different between BASE and HT (P > 0.05). However, total time asleep was significantly reduced (P = 0.01; d = 1.46) and the duration periods of wakefulness after sleep onset was significantly greater during HT compared with BASE (P = 0.001; d = 1.14). Comparison between training groups showed latency was significantly higher for the 30HIT group compared to 90CONT (P = 0.02; d = 1.33). Nevertheless, there were no differences between training groups for sleep efficiency, total time in bed or asleep, wake after sleep onset, number of awakenings or awake duration (P > 0.05). Further, cold-water immersion recovery had no significant effect on sleep characteristics (P > 0.05). - Discussion Sleep plays an important role in athletic recovery and has previously been demonstrated to be influenced by both exercise training and thermal strain. Present data highlight the effect of HT on reduced sleep quality, specifically reducing total time asleep due to longer duration awake during awakenings after sleep onset. Importantly, although cold water recovery accelerates the removal of thermal load, this intervention did not blunt the negative effects of HT on sleep characteristics. - Conclusion Training in hot conditions may reduce both sleep quantity and quality and should be taken into consideration when administering this training intervention in the field.

The problem of liquid droplet combustion-reexamination

The simple quasi-steady analysis of the combustion of a liquid fuel droplet in an oxidising atmosphere provides unsatisfactory explanations for several experimental observations. It's prediction of values for the burning constant (K), the flame-to-droplet diameter ratio ( ) and the flame temperature (Tf) have been found to be amgibuous if not completely inaccurate. A critical survey of the literature has led us to a detailed examination of the effects of unsteadiness and variable properties. The work published to date indicates that the gas-phase unsteadiness is relatively short and therefore quite insignificant.A new theoretical analysis based on heat transfer within the droplet is presented here. It shows that the condensed-phase unsteadiness lasts for about 20â??25% of the total burning time. It is concluded that the discrepancies between experimental observations and the predictions of the constant-property quasi-steady analysis cannot be attributed either to gas-phase or condensed-phase unsteadiness.An analytical model of quasi-steady droplet combustion with variable thermodynamic and transport properties and non-unity Lewis numbers will be examined. Further findings reveal a significant improvement in the prediction of combustion parameters, particularly of K, when consideration is given to variations of cp and λ with the temperature and concentrations of several species. Tf is accurately predicted when the required conditions of incomplete combustion or low ( ) at the flame are met. Further refinement through realistic Lewis numbers predicts ( ) meaningfully.

Characterization of vitamin A transport system from goat plasma

Retinol-binding protein and its complex with prealbumin were isolated from goat serum by chromatography on DEAE-Sephadex A-50, gel filtration and immuno-affinity chromatography on antigoat-serum albumin-Sepharose 4B. The homogeneous prealbumin-retinol-binding protein complex had a molecular weight of 75 000. Both on electrophoresis and in the presence of 2 M urea, the complex dissociated into retinol-binding protein and prealbumin. The molecular weight, electrophoretic behaviour, ultraviolet and fluorescence spectra of goat retinol-binding protein were similar to those isolated from other sources. On sodium dodecyl sulphate gel electrophoresis, goat prealbumin (molecular weight ≈ 55 000) exhibited two bands corresponding to molecular weights 26 000 and 13 000. This suggests that either goat prealbumin consists of two non-identical sub-units or perhaps complete dissociation might not have occurred. Goat prealbumin was able to bind Image -thyroxine and retinol-binding protein.

Numerical study of heat transfer in laminar film boiling by the finite-difference method

The finite-difference form of the basic conservation equations in laminar film boiling have been solved by the false-transient method. By a judicious choice of the coordinate system the vapour-liquid interface is fitted to the grid system. Central differencing is used for diffusion terms, upwind differencing for convection terms, and explicit differencing for transient terms. Since an explicit method is used the time step used in the false-transient method is constrained by numerical instability. In the present problem the limits on the time step are imposed by conditions in the vapour region. On the other hand the rate of convergence of finite-difference equations is dependent on the conditions in the liquid region. The rate of convergence was accelerated by using the over-relaxation technique in the liquid region. The results obtained compare well with previous work and experimental data available in the literature.

Heat transfer to power-law fluids in thermal entrance region with viscous dissipation for constant heat flux conditions

An analytical solution of the heat transfer problem with viscous dissipation for non-Newtonian fluids with power-law model in the thermal entrance region of a circular pipe and two parallel plates under constant heat flux conditions is obtained using eigenvalue approach by suitably replacing one of the boundary conditions by total energy balance equation. Analytical expressions for the wall and the bulk temperatures and the local Nusselt number are presented. The results are in close agreement with those obtained by implicit finite-difference scheme. It is found that the role of viscous dissipation on heat transfer is completely different for heating and cooling conditions at the wall. The results for the case of cooling at the wall are of interest in the design of the oil pipe line.

A possible explanation of the Maunder minimum from a flux transport dynamo model

We propose that the poloidal field at the end of the last sunspot cycle before the Maunder minimum fell to a very low value due to fluctuations in the Babcock-Leighton process. With this assumption, a flux transport dynamo model is able to explain various aspects of the historical records of the Maunder minimum remarkably well by suitably choosing the parameters of the model to give the correct growth time.

Field-Effect and Frequency Dependent Transport in Semiconductor-Enriched Single-Wall Carbon Nanotube Network Device

The electrical and optical response of a field-effect device comprising a network of semiconductor-enriched single-wall carbon nanotubes, gated with sodium chloride solution is investigated. Field-effect is demonstrated in a device that uses facile fabrication techniques along with a small-ion as the gate electrolyte-and this is accomplished as a result of the semiconductor enhancement of the tubes. The optical transparency and electrical resistance of the device are modulated with gate voltage. A time-response study of the modulation of optical transparency and electrical resistance upon application of gate voltage suggests the percolative charge transport in the network. Also the ac response in the network is investigated as a function of frequency and temperature down to 5 K. An empirical relation between onset frequency and temperature is determined.

Studies on transport phenomena during solidification of an aluminum alloy in the presence of linear electromagnetic stirring

Numerical and experimental studies on transport phenomena during solidification of an aluminum alloy in the presence of linear electromagnetic stirring are performed. The alloy is electromagnetically stirred to produce semisolid slurry in a cylindrical graphite mould placed in the annulus of a linear electromagnetic stirrer. The mould is cooled at the bottom, such that solidification progresses from the bottom to the top of the cylindrical mould. A numerical model is developed for simulating the transport phenomena associated with the solidification process using a set of single-phase governing equations of mass. momentum, energy. and species conservation. The viscosity variation of the slurry, used in the model, is determined experimentally using a rotary viscometer. The set of governing equations is solved using a pressure-based finite volume technique, along with an enthalpy based phase change algorithm. The numerical study involves prediction of temperature, velocity, species and solid fraction distribution in the mould. Corresponding solidification experiments are performed, with time-temperature history recorded at key locations. The microstructures at various temperature measurement locations in the solidified billet are analyzed. The numerical predictions of temperature variations are in good agreement with experiments, and the predicted flow field evolution correlates well with the microstructures observed at various locations.

Response of a turbulent boundary layer to a step change in surface heat flux

Measurements of both the velocity and the temperature field have been made in the thermal layer that grows inside a turbulent boundary layer which is subjected to a small step change in surface heat flux. Upstream of the step, the wall heat flux is zero and the velocity boundary layer is nearly self-preserving. The thermal-layer measurements are discussed in the context of a self-preserving analysis for the temperature disturbance which grows underneath a thick external turbulent boundary layer. A logarithmic mean temperature profile is established downstream of the step but the budget for the mean-square temperature fluctuations shows that, in the inner region of the thermal layer, the production and dissipation of temperature fluctuations are not quite equal at the furthest downstream measurement station. The measurements for both the mean and the fluctuating temperature field indicate that the relaxation distance for the thermal layer is quite large, of the order of 1000θ0, where θ0 is the momentum thickness of the boundary layer at the step. Statistics of the thermal-layer interface and conditionally sampled measurements with respect to this interface are presented. Measurements of the temperature intermittency factor indicate that the interface is normally distributed with respect to its mean position. Near the step, the passive heat contaminant acts as an effective marker of the organized turbulence structure that has been observed in the wall region of a boundary layer. Accordingly, conditional averages of Reynolds stresses and heat fluxes measured in the heated part of the flow are considerably larger than the conventional averages when the temperature intermittency factor is small.

Lidar heat map based channel sounding for complex wireless environments

This thesis is a development of a methodology to predict the radio transmitter signal attenuation, via vertical density profiling of digitised objects, through the use of Light Detection and Ranging (LiDaR) measurements. The resulting map of indexed signal attenuation is useful for dynamic radio transmitter placement within the geospatial data set without expensive and tedious radio measurements.

A comparative study of the early effects of phenobarbital and 3-methylcholanthrene on the synthesis and transport of ribonucleic acid in rat liver.

At 2-3 h after phenobaribtal administration, the drug has no effect on nucleoplasmic RNA synthesis and decreases nucleolar RNA synthesis. However, at this time there is an increase in the labelling of cytoplasmic poly(A)-containing RNA, even though there is decreased labelling of total polyribosomal RNA. The decrease in labelling of nucleolar and total polyribosomal RNA owing to phenobarbital is a transient phenomenon. Under similar conditions, 3-methylcholanthrene has no effect on nucleolar RNA synthesis, but leads to an increase in synthesis of nucleoplasmic and cytoplasmic poly(A)-containing RNA. Cytosol isolated from phenobarbital-treated, but not from 3-methyl-cholanthrene-treated, animals facilitates an enhanced transport of RNA from nuclei. At the time points investigated, 3-methylcholanthrene or its metabolite shows a 10-15-fold higher concentration in the chromatin than that of phenobarbital or its metabolite. It is suggested that the primary effect of phenobarbital is at the cytoplasmic level, promoting the transport of RNA from the nuclei, which can act as a trigger for enhanced transcription at later periods. 3-Methylcholanthrene or its metabolite directly binds to the chromatin and evokes a selective transcriptional response.

Electrochromic, magnetotransport and AC transport properties of vapor phase polymerized PEDOT(VPP PEDOT)

Poly(3,4-ethylenedioxy)thiophene (PEDOT) doped with tosylate ion (PEDOT-tosylate or VPP PEDOT) was synthesized by vapor phase polymerization (VPP) technique on glass as well as on glass/ITO and the electrochromic properties were investigated. Compared with that of PEDOT-PSS spin-coated on glass/ITO, the studies showed that VPP PEDOT has a lower work function and better electrochromic properties. The magneto and AC transport properties studies were done on VPP PEDOT coated on glass substrate. The system shows 2-dimensional variable range hopping and wave function shrinkage of charge carriers.

Light and heat induced interdiffusion in Sb/As2S3 nano-multilayered film

The light and heat induced changes in the optical band gap of Sb/As2S3 nanomultilayered chalcogenide film has been studied. Even though the changes in optical bandgap are attributed to the light and heat induced interdiffusion, the diffusional intermixing between the layers is rather different with light and heat. The observed difference in the light and heat induced interdiffusion is due to unequal diffusion coefficients of light and heat predicted by thermal spike model.