Circadian and circannual variations in growth and cold resistance of warm acclimated rats and their relationship with the geomagnetic activity

In winter, summer, spring and fall, groups of 200 g Sprague Dawley male rats were kept for 14 days at constant Ta 28°C±°C and LD 12:12(07:00–19:00 h). They were fed a laboratory chow (P) or a semi-purified diet (H). They were weighed at 0, 7 and 14 days. Cold resistance was determined by the fall in rectal temperature during 4 hours of restrained exposure to +1°C either in the morning (09:00 – 13:00 h) or in the afternoon (14:00 – 18:00 h). Rats fed the H diet could better tolerate cold exposure in the morning than in the afternoon, whereas the chow-fed rats were more vulnerable and became severely hypothermic both in morning and afternoon. The greater morning resistance provided by the H diet was evident in summer and winter but not in spring or fall. With both diets, cold resistance as well as growth decreased during spring and fall. Frozen storage of the diets and the water for use during other seasons showed that the nutrients per se were not a factor in the observed seasonal cycle. Although humidity in the 28°C room varied between a minimum of 26.5% in April to a maximum of 44.3% in August, it was not a statistically significant factor in the growth cycle. Arguments are presented to rule out relative humidity as a significant factor in the seasonal variation in the degree of cold resistance. A significant correlation was found for growth and cold resistance with geomagnetic activity.NRCC # 17310     

Breakfast in the nook and dinner in the dining room: time-of-day discrimination in rats

Four studies were conducted which demonstrate that most (63%) male Sprague-Dawley rats can attain criterion, nine correct choices over ten consecutive trials, on a time-of-day discrimination in an elevated T-maze, but that the task is relatively difficult. The discrimination required that the rats go to one goal arm during a morning session and the other in an afternoon session. The sessions always began at the same time and were at least 6 h apart. A larger proportion of rats attained criterion and required fewer trials when the discriminative cue was a maze insert providing visual and tactile stimulation (0.72), orientation and position of the maze in the room (0.88), or the rats were required to always make the same left or right turn (0.94). Also, once criterion was attained, rats trained on time-of-day discrimination only made about 70% correct choices with continued training. Housing the rats with continuous light, all laboratory noises masked with white noise, and a random feeding schedule did not prevent them from acquiring the time-place discrimination. Testing the rats with a random number of trials during morning and afternoon sessions and with added or omitted sessions revealed that the rats did not use response or session alternation strategies to perform the discrimination. Also, the particular experimenter administering the morning or afternoon sessions did not serve as a cue for the discrimination. The relative difficulty of the task suggests that time of day does not normally function as a discriminative stimulus for choices, but probably as a contextual stimulus. Further, performance of the task in the absence of time-of-day cues suggests that the discrimination is based on event memory combined with an internal timing mechanism.     

Mixotrophic growth ofChlorella sorokiniana in outdoor enclosed photobioreactor

Chlorella sorokiniana was cultured in heterotrophic or mixotrophic mode in outdoor enclosed tubular photobioreactor. The culture temperature was maintained at 32–35 °C. At night, theChlorella culture grew heterotrophically, and 0.1 M glucose was completely consumed. The biomass growth yield of glucose was 0.35 ± 0.001 g-biomass g-glucose^–1. During the day, the algal culture grew mixotrophically and the biomass growth yield was 0.49 g-biomass g-glucose^–1 in low density culture (initial biomass concentration, X_o = 2 g l^–1), 0.56 g-biomass g-glucose^–1 in medium density culture (X_o = 4 g l^–1) and 0.46 g-biomass g-glucose^–1 in high density culture (X_o = 7 g l^–1). The daily area productivity of the culture, with X_o = 4 g l^–1 corresponded to 127 g-biomass m^–2 d^–1 during the day and 79 g-biomass m^–2 d^–1 during the night. In all the cultures, the dissolved O₂ concentration increased in the morning, reached the maximum value at noon, and then decreased in the afternoon. The dissolved CO₂ concentration remained at 3 mBar in the morning and increased in the afternoon. Glycolate was not found to accumulate in culture medium.     

Diurnal variation and reliability of the urine lactate concentration after maximal exercise

The postexercise urine lactate concentration is a novel valid exercise biomarker, which has exhibited satisfactory reliability in the morning hours under controlled water intake. The aim of the present study was to investigate the diurnal variation of the postexercise urine lactate concentration and its reliability in the afternoon hours. Thirty-two healthy children (11 boys and 21 girls) and 23 adults (13 men and 10 women) participated in the study. All participants performed two identical sessions of eight 25 m bouts of maximal freestyle swimming executed every 2 min with passive recovery in between. These sessions were performed in the morning and afternoon and were separated by 3–4 days. Adults performed an additional afternoon session that was also separated by 3–4 days. All swimmers drank 500 mL of water before and another 500 mL after each test. Capillary blood and urine samples were collected before and after each test for lactate determination. Urine creatinine, urine density and body water content were also measured. The intraclass correlation coefficient was used as a reliability index between the morning and afternoon tests, as well as between the afternoon test and retest. Swimming performance and body water content exhibited excellent reliability in both children and adults. The postexercise blood lactate concentration did not show diurnal variation, showing a good reliability between the morning and afternoon tests, as well as high reliability between the afternoon test and retest. The postexercise urine density and lactate concentration were affected by time of day. However, when lactate was normalized to creatinine, it exhibited excellent reliability in children and good-to-high reliability in adults. The postexercise urine lactate concentration showed high reliability between the afternoon test and retest, independent of creatinine normalization. The postexercise blood and urine lactate concentrations were significantly correlated in all cases, attesting to the validity of urine lactate as an index of anaerobic metabolism. We conclude that urine lactate, after normalization to creatinine, could be used in training practice either in the morning or in the afternoon. Further research is needed to assess the applicability of this novel exercise biomarker.     

The effects of low fat chocolate milk on postexercise recovery in collegiate athletes

Spaccarotella, KJ and Andzel, WD. The effects of low fat chocolate milk on postexercise recovery in collegiate athletes. J Strength Cond Res 25(12): 3456-3460, 2011-Drinking chocolate milk between exercise sessions may improve recovery. The purpose of this study was to examine the effects of low fat chocolate milk vs. a carbohydrate-electrolyte beverage (CE) on recovery between preseason practice sessions among 5 male and 8 female Division III soccer players. The study used a randomized crossover design: between morning and afternoon practices, athletes received either an amount of chocolate milk that provided 1 g carbohydrate per kilogram body weight or an equal volume of CE (mean volume of 615 ± 101 ml). After their afternoon practice, they completed a shuttle run to fatigue. Data were analyzed using the Wilcoxon paired rank-sign test (for shuttle run time) and the paired samples t-test (for dietary intake). No significant differences in run time were reported for the group. For the men only, there was a trend of increased time to fatigue with chocolate milk compared with the CE (exact p = 0.03). Low fat chocolate milk may therefore be as good as a CE at promoting recovery between training sessions during preseason.     

A Temporal Dimension to the Influence of Pollen Rewards on Bee Behaviour and Fecundity in Aloe tenuior

The net effect of pollen production on fecundity in plants can range from negative – when self-pollen interferes with fecundity due to incompatibility mechanisms, to positive – when pollen availability is associated with increased pollinator visitation and fecundity due to its utilization as a reward. We investigated the responses of bees to pollen and nectar rewards, and the effects of these rewards on pollen deposition and fecundity in the hermaphroditic succulent shrub Aloe tenuior. Self-pollinated plants failed to set fruit, but their ovules were regularly penetrated by self-pollen tubes, which uniformly failed to develop into seeds as expected from ovarian self-incompatibility (or strong early inbreeding depression). Bees consistently foraged for pollen during the morning and early afternoon, but switched to nectar in the late afternoon. As a consequence of this differential foraging, we were able to test the relative contribution to fecundity of pollen- versus nectar-collecting flower visitors. We exposed emasculated and intact flowers in either the morning or late afternoon to foraging bees and showed that emasculation reduced pollen deposition by insects in the morning, but had little effect in the afternoon. Despite the potential for self-pollination to result in ovule discounting due to late-acting self-sterility, fecundity was severely reduced in artificially emasculated plants. Although there were temporal fluctuations in reward preference, most bee visits were for pollen rewards. Therefore the benefit of providing pollen that is accessible to bee foragers outweighs any potential costs to fitness in terms of gender interference in this species.     

Selective Effect of Physical Fatigue on Motor Imagery Accuracy

While the use of motor imagery (the mental representation of an action without overt execution) during actual training sessions is usually recommended, experimental studies examining the effect of physical fatigue on subsequent motor imagery performance are sparse and yielded divergent findings. Here, we investigated whether physical fatigue occurring during an intense sport training session affected motor imagery ability. Twelve swimmers (nine males, mean age 15.5 years) conducted a 45 min physically-fatiguing protocol where they swam from 70% to 100% of their maximal aerobic speed. We tested motor imagery ability immediately before and after fatigue state. Participants randomly imagined performing a swim turn using internal and external visual imagery. Self-reports ratings, imagery times and electrodermal responses, an index of alertness from the autonomic nervous system, were the dependent variables. Self-reports ratings indicated that participants did not encounter difficulty when performing motor imagery after fatigue. However, motor imagery times were significantly shortened during posttest compared to both pretest and actual turn times, thus indicating reduced timing accuracy. Looking at the selective effect of physical fatigue on external visual imagery did not reveal any difference before and after fatigue, whereas significantly shorter imagined times and electrodermal responses (respectively 15% and 48% decrease, p<0.001) were observed during the posttest for internal visual imagery. A significant correlation (r = 0.64; p<0.05) was observed between motor imagery vividness (estimated through imagery questionnaire) and autonomic responses during motor imagery after fatigue. These data support that unlike local muscle fatigue, physical fatigue occurring during intense sport training sessions is likely to affect motor imagery accuracy. These results might be explained by the updating of the internal representation of the motor sequence, due to temporary feedback originating from actual motor practice under fatigue. These findings provide insights to the co-dependent relationship between mental and motor processes.     

DIURNAL VARIATION IN WINGATE TEST PERFORMANCES: INFLUENCE OF ACTIVE WARM-UP

The purpose of the present study was to examine the effects of active warm-up duration on the diurnal fluctuations in anaerobic performances. Twelve physical education students performed a medical stress test (progressive test up to exhaustion) and four Wingate tests (measurement of peak power [P_peak], mean power [P_mean], and fatigue index during an all-out 30 s cycling exercise). The tests were performed in separate sessions (minimum interval?=?36?h) in a balanced and randomized design at 08:00 and 18:00?h, either after a 5?min (5-AWU) or a 15?min active warm-up (15-AWU). AWU consisted of pedaling at 50% of the power output at the last stage of the stress exhausting test. Rectal temperature was collected throughout the sessions. A two-way ANOVA (warm-up?×?time of day) revealed a significant interaction for P_peak (F_(1.11)?=?6.48, p?<?0.05) and P_mean (F_(1.11)?=?5.84, p?<?0.05): the time-of-day effect was significant (p?<?0.001) in contrast with the effect of warm-up duration (p?>?0.05). P_peak and P_mean improved significantly from morning to afternoon after both 5-AWU and 15-AWU, but the effect of warm-up duration was significant in the morning only. Indeed, the values of P_peak or P_mean were the same after both warm-up protocols in the afternoon. For rectal temperature, there was no interaction between time-of-day and warm-up duration. Rectal temperature before and after both the warm-up protocols was higher in the afternoon, and the effect of warm-up duration on temperature was similar at 08:00 and 18:00?h. In conclusion, the interpretation of the results of the anaerobic performance tests should take into account time-of-day and warm-up procedures. Longer warm-up protocols are recommended in the morning to minimize the diurnal fluctuations of anaerobic performances. (Author correspondence: n_souissi@yahoo.fr)     

Does post-warm-up rest interval affect the diurnal variation of 30-s Wingate cycle ergometry?

The purpose of this investigation was to assess the effects of rest interval following active warm-up (WU) durations on the diurnal variation of high-intensity cycling performance. Eleven male physical education students (22.6 ± 2.5 years; 179.2 ± 5.7 cm; 82.6 ± 9.6 kg; mean ± SD) participated in a cross-over randomized study, and they all underwent the 30-s Wingate test in the morning (08:00 h) and in the evening (18:00 h), after 5-min (WU₅) and 15-min (WU₁₅) warm-up durations, either with rest (WR), or without rest interval (NR) separating the WU at the onset of the high-intensity cycling exercise performance. The WU consisted of pedaling at a constant pace of 60 rpm against at 50% of the maximal aerobic power. The rest interval between the end of warm-up and the beginning of the anaerobic exercise was set at 5 min. Peak power (PP), mean power (MP), and the fatigue index (FI) were recorded. Likewise, heart rate, oral temperature (T), and rating of perceived exertion were registered at rest, at the end of the WU and just after the Wingate test. The ANOVA’s showed no main effect of the rest interval on PP, MP, FI, and T parameters. However, significant interactions (WU duration × time-of-day and recovery condition × WU duration) were recorded on both PP and MP parameters. PP and MP were higher in the afternoon compared to the morning with gains of 4.4 and 3.6%, respectively. In the morning sessions, the WU₁₅ allows better improvement of muscular power, with either 0- or 5-min pre-exercise rest interval. However, in the afternoon sessions, both WU₁₅ and WU₅ durations allow better improvement of 30-s Wingate cycling performance in, respectively, WR and NR conditions. Therefore, athletes and coaches, as well as researchers, interested in high-intensity cycling exercise, should take into account the rest interval, the time-of-day, and the duration of warm-up when practicing, assessing, or interpreting data related to powerful lower limbs’ muscles contractions activities.     

Sleep pressure and time perception in university students

Here we aimed to investigate the association between poor quality of sleep, sleep debt during weekdays and the performance on an interval timing task, using the method of production of time and consisting on five sessions a day for nine days. The sleep of our volunteers was particularly restricted on weekdays. Moreover, later chronotype was associated with the need for compensation on weekends. Regarding the production of time, produced durations were consistently over-produced and there was an evident increase in the mean coefficient of variation (CV) from the wake-up morning to afternoon sessions, followed by a sharp decrease in the evening sessions. Importantly, CV was mainly determined by the interaction between MSFdiff, sleep duration on weekdays and age. In conclusion, our results indicate that when university students are under the effects of social jet lag and reduced sleep duration during weekdays, their performance in interval timing tasks may be compromised.     

The Association between Daytime Napping and Cognitive Functioning in Chronic Fatigue Syndrome

Objectives

The precise relationship between sleep and physical and mental functioning in chronic fatigue syndrome (CFS) has not been examined directly, nor has the impact of daytime napping. This study aimed to examine self-reported sleep in patients with CFS and explore whether sleep quality and daytime napping, specific patient characteristics (gender, illness length) and levels of anxiety and depression, predicted daytime fatigue severity, levels of daytime sleepiness and cognitive functioning, all key dimensions of the illness experience.

Methods

118 adults meeting the 1994 CDC case criteria for CFS completed a standardised sleep diary over 14 days. Momentary functional assessments of fatigue, sleepiness, cognition and mood were completed by patients as part of usual care. Levels of daytime functioning and disability were quantified using symptom assessment tools, measuring fatigue (Chalder Fatigue Scale), sleepiness (Epworth Sleepiness Scale), cognitive functioning (Trail Making Test, Cognitive Failures Questionnaire), and mood (Hospital Anxiety and Depression Scale).

Results

Hierarchical Regressions demonstrated that a shorter time since diagnosis, higher depression and longer wake time after sleep onset predicted 23.4% of the variance in fatigue severity (p <.001). Being male, higher depression and more afternoon naps predicted 25.6% of the variance in objective cognitive dysfunction (p <.001). Higher anxiety and depression and morning napping predicted 32.2% of the variance in subjective cognitive dysfunction (p <.001). When patients were classified into groups of mild and moderate sleepiness, those with longer daytime naps, those who mainly napped in the afternoon, and those with higher levels of anxiety, were more likely to be in the moderately sleepy group.

Conclusions

Napping, particularly in the afternoon is associated with poorer cognitive functioning and more daytime sleepiness in CFS. These findings have clinical implications for symptom management strategies.     

The periodicities in and biometeorological relationships with bed occupancy of an acute psychiatric ward in Antwerp,Belgium

Recently, some investigators have established a seasonal pattern in normal human psychology, physiology and behaviour, and in the incidence of psychiatric psychopathology. In an attempt to elucidate the chronopsy and meteotropism in the latter, we have examined the chronograms of, and the biometeorological relationships to bed occupancy of the psychiatric ward of the Antwerp University Hospital during three consecutive calendar years (1987–1989). Weather data for the vicinity were provided by a local meteorological station and comprise mean atmospheric pressure, air temperature, relative humidity, wind speed and minutes of sunlight and precipitation/day. The number of psychiatric beds occupied during the study period exhibited a significant seasonal variation. Peaks in bed occupancy were observed in March and November, with lows in August. An important part of the variability in the number of beds occupied could be explained by the composite effects of weather variables of the preceding weeks. Our results suggest that short-term fluctuations in atmospheric activity may dictate some of the periodicities in psychiatric psychopathology.     

Diurnal Variation in Glucose Tolerance: Associated Changes in Plasma Insulin,Growth Hormone,and Non-esterified

Oral glucose tolerance tests were performed in the morning and afternoon of separate days on 31 people derived from a normal population sample. Blood sugar levels were higher in the afternoon test from and including 60 minutes after the glucose load. The degree of diurnal variation was similar in men and women, but greater in the older half of the group. It was negatively correlated with the degree of obesity. The plasma insulin response was less at the 30 minute time point in the afternoon, but significantly exceeded the morning values at 120 and 150 minutes after the glucose load. Growth hormone levels were similar in morning and afternoon tests. Fasting non-esterified fatty acid levels were significantly higher before the afternoon test.The relatively impaired glucose tolerance in the afternoon is associated with a delayed insulin response to the glucose load. This seems unlikely to be the sole explanation, however, and increased non-esterified fatty acid metabolism with a consequent decrease in glucose disposal may also contribute.     

Summer monsoon precipitation variations in central China over the past 750 years derived from a high-resolution absolute-dated stalagmite

A 2–3-year resolution record of stalagmite oxygen isotope variations from the south flank of the Qinling Mountains, central China, has revealed the Asian summer monsoon (ASM) precipitation variations in the investigated area over the past 750 years. The summer monsoon precipitation gradually increased since 1249 AD, reaching its highest values in the period 1535–1685 AD, and then decreased with substantial decadal- to centennial-scale fluctuations. The monsoon precipitation increased again between 1920 and 1970 AD. Three intervals of high monsoon precipitation were identified: 1535–1685 AD, 1755–1835 AD, and 1920–1970 AD. Three intervals of low precipitation were inferred in 1249–1325 AD, 1390–1420 AD, and 1890–1915 AD. The δ¹⁸O composition and lithological features of the stalagmite coincidently indicate a wetter climate during the Little Ice Age (LIA), which is also confirmed by climate records from Chinese historical documents within this area. A comparison with other high-resolution speleothem records indicates regional differences in monsoon precipitation variability from the south to the north of central China in the last 750 years on decadal- to centennial-scale. Power spectrum analysis of the δ¹⁸O record shows significant 117.8-, 34.6-, 14-, 10.3-, and ~ 6-year periodicities. These periodicities are widely observed in the climate records from ASM-controlled areas of China and are consistent with the Gleissburg periodicity, Brϋckner periodicity, sunspot periodicity of solar activity, and El Nińo–Southern Oscillation (ENSO) periodicity. These correlations suggest that both solar activity and ENSO periodicity may have had important influences on ASM precipitation in China over the past 750 years.     

Afternoon Nap and Bright Light Exposure Improve Cognitive Flexibility Post Lunch

Beneficial effects of napping or bright light exposure on cognitive performance have been reported in participants exposed to sleep loss. Nonetheless, few studies investigated the effect of these potential countermeasures against the temporary drop in performance observed in mid-afternoon, and even less so on cognitive flexibility, a crucial component of executive functions. This study investigated the impact of either an afternoon nap or bright light exposure on post-prandial alterations in task switching performance in well-rested participants. Twenty-five healthy adults participated in two randomized experimental conditions, either wake versus nap (n=15), or bright light versus placebo (n=10). Participants were tested on a switching task three times (morning, post-lunch and late afternoon sessions). The interventions occurred prior to the post-lunch session. In the nap/wake condition, participants either stayed awake watching a 30-minute documentary or had the opportunity to take a nap for 30 minutes. In the bright light/placebo condition, participants watched a documentary under either bright blue light or dim orange light (placebo) for 30 minutes. The switch cost estimates cognitive flexibility and measures task-switching efficiency. Increased switch cost scores indicate higher difficulties to switch between tasks. In both control conditions (wake or placebo), accuracy switch-cost score increased post lunch. Both interventions (nap or bright light) elicited a decrease in accuracy switch-cost score post lunch, which was associated with diminished fatigue and decreased variability in vigilance. Additionally, there was a trend for a post-lunch benefit of bright light with a decreased latency switch-cost score. In the nap group, improvements in accuracy switch-cost score were associated with more NREM sleep stage N1. Thus, exposure to bright light during the post-lunch dip, a countermeasure easily applicable in daily life, results in similar beneficial effects as a short nap on performance in the cognitive flexibility domain with possible additional benefits on latency switch-cost scores.     

Behavioural thermoregulation of the Andean toad (Bufo spinulosus) at high altitudes

Summary The body temperature of free-ranging Andean toadsBufo spinulosus was measured either directly or radiotelemetrically during two 15-day periods at 3200 m elevation in the Mantaro Valley, Central Perú. All toads attempted to maintain their diurnal sum of body temperature within a narrow range. Consequently thermoregulatory behaviour differed according to cloud cover and precipitation. If the sky was clear, toads emerged from their hiding place and exposed themselves to solar radiation during 3–5 h in the morning. Core temperature increased up to 15° C above the air temperature in shade and reached maximum values of about 32° C. At air temperatures (in sun) exceeding 29° C, toads maintained body temperatures below 32° C by evaporative cooling. Following heliothermic heating during the moring toads retreated to the shade, thereby decreasing body temperature below air temperature. Under overcast sky toads remained exposed during the whole day displaying body temperatures at or slightly above ambient levels. Quantitative models to predict the core temperature of toads under the different weather conditions demonstrated that the substrate temperature was the main energy source accounting for 64.6–77.9% of total variance whereas air temperature was of minor importance (1.5–4.4%). The unexplained variance was probably due to evaporative cooling. The volume of urine stored into the urinary bladder of toads varied diurnally; during basking in the morning hours most bladders contained large volumes of urine, whereas during the afternoon the bladders were mostly empty. The bladder contents probably serve as water reserves during basking when evaporative water loss was high. Toads preferred sites that provided shady hiding places as well as sun-exposed bare soil within a radius of 5 m. However, they frequently changed their centers of activity and moved to other sites in 20–70 m distance after periods of 2–5 days. The helio-and thigmothermic behaviour of the Andean toad permits the maintenance of high core temperature during morning which probably increases the digestion rate and accelerate growth. Evaporative cooling and preference of shady sites were employed to regulate body temperature below the morning levels in response to the constraints of water balance. Periodic changes between thigmothermic behaviour and locomotory activity during the night maintains body temperature above air temperature and prolongs the period of food uptake.Dedicated to Prof. Dr. H. Schneider on the occasion of his sixtieth birthday     

Within and between day variability in coral reef fish assemblages: Implications for fish community surveys

Coral reef ecosystems are under increasing anthropogenic pressures making it ever more important to monitor changes in fish communities to implement appropriate management. In contrast to long-term spatial and temporal variation which has been extensively documented, little work has been carried out to identify variability in fish assemblages on short time scales, with few studies testing patterns of fish assemblages between and within days. Here we investigated the diurnal changes in species richness, relative abundance and assemblage composition in a shallow coral reef fish community in Egypt. To do so, a section of coral reef was filmed during the morning (0600 h), midday (1000 and 1400 h) and afternoon (1800 h) over eleven days. Dusk (0600 h) and dawn samples (1800 h) showed higher species richness compared to late morning (1000 h) and mid-day samples (1400 h) and borderline significantly higher numbers of total individuals, likely associated with feeding activity and predator avoidance. Assemblage composition varied across days and time-of-day, showing greater variability during dusk and dawn associated with a transition between day-time and night-time assemblages. Our results have implications for designing coral reef fish surveys, emphasising that short-term changes in fish communities should be considered when designing experiments to monitor fish assemblages over time. Where possible, we suggest increasing replication within sites and time scales or randomising data within a specific time window at all sites, looking to exclude dusk and dawn.     

The relative efficacy of autogenic phrases and autogenic-feedback training in teaching hand warming to children

There are few well-controlled biofeedback temperature training studies in the literature that have used children as subjects. The purposes of this study were (1) to evaluate whether children can learn to increase hand temperature, controlling for methodological factors that have been overlooked in previous experiments, and (2) to determine whether adding thermal biofeedback to autogenic phrases results in improved ability to produce voluntary increases in hand temperature over the use of autogenic phrases alone. Twenty-six subjects (ages 9–11) were divided into two groups of 13 subjects each. All subjects participated in four 35 to 45-minute sessions consisting of a stabilization phase, a training phase, and a post-training phase on 4 consecutive days. One group was trained to increase finger temperature with autogenic phrases only, and the other was trained with autogenic phrases plus thermal feedback. None of the subjects in either group learned to increase hand temperature significantly within sessions. There was a consistent and reliable decreasing trend within each session; however, finger temperature did increase (.27° F) for the first 8 minutes of the training phase. There was a significant increase in hand temperature from day 1 to days 3 and 4, and there were significant increases in temperature during the stabilization phase alone. There were no differential effects of treatments. Methodological issues concerning stabilization, the potential confounding effect of boredom and fatigue, and different training methods for children are discussed.     

Configuration of daily grazing and searching of growing beef cattle in grassland: observational study

Many of the studies in Campos grasslands focus on management aspects such as the control of herbage allowance, and application of nutrients and/or overseeding with legumes. However, there is little literature on how the Campos grassland resource is utilised, especially regarding the grazing pattern and the relationship between pasture quantity and quality on daily grazing activities. The study of the ingestive behaviour in species-rich and heterogeneous native grasslands during daylight hours, and understanding how animals prioritise quality or quantity of intake in relation to pasture attributes, are important to comprehend the ingestive-digestive processes modulating the energy intake of animals and to achieve a better grazing management. Therefore, the objective was to describe and quantify the daily grazing behaviour of growing cattle grazing native pasture with different structures as a result of different management practices, and study the relationship of pasture attributes and intake through multivariate analysis. The study was carried out at the Faculty of Agronomy, Paysandú, Uruguay. Treatments were native grassland, overseeding with Trifolium pratense and Lotus tenuis + phosphorus, and native pasture + nitrogen-phosphorus. Grazing activities were discriminated into grazing, searching (defined when animals take 1–2 bites in one feeding station and then change to another feeding station and so on), ruminating and idling. The probability of time allocated to each activity was continuously measured during daylight hours (0700–1930) and was related to pasture structure and forage quality using regression tree models, while the bite rate was determined every 2 h. The diurnal pattern of growing cattle showed grazing and searching sessions, followed by ruminating and idling sessions. The length of sessions (as the probability of time allocated to each activity) varied throughout the day. The grazing probability was greater during afternoon than morning and midday (0.74 vs 0.45 vs 0.46, respectively), and it was associated with higher bite rate (34.2 bites/min). Regression tree models showed different grazing, searching and ruminating strategies according to pasture attributes. During the morning, animals modified grazing, searching, ruminating and idling strategies according to bite rate, crude protein in diet and herbage allowance. At midday, they only adjusted ruminating and idling, while during afternoon sessions, grazing activities were modified by pasture quantity attributes such as herbage mass and herbage allowance. By controlling the herbage allowance, herbage mass and pasture height, animals prioritise quality in the morning and quantity in the afternoon, integrating and modifying the grazing-searching and ruminating-idling pattern.