SCENARIO revisited: comparisons of operational and rational models in predicting human responses to the environment

1. This paper focuses on thermoregulatory modeling of individual variability in environmental extremes.

2. A great many worthwhile models do a reliable job describing the heat balance equation using a first principles approach by fitting operational equations or by using multi-node thermoregulatory servo-control models.

3. A soldier-based physiological/thermoregulatory model (SCENARIO (J. Therm. Biol. 22 (1997) 331) was enhanced using a probabilistic application of the Bayesian statistical paradigms in conjunction with Monte Carlo methods (SCENARIO-MC).

4. Coefficients improving the model include: algorithms for circadian and menstrual cycle offsets on the hypothalamic controller and an output depiction of correlation matrices between specific environmental and physiologic variables.

5. The model was found to be robust (based on root mean square deviations ) particularly in physiological strain index prediction and able to predict individual esophageal and heart rate responses in women exposed to upward and downward thermal transients and wide perturbations of work/rest exercise in the heat while wearing protective clothing.

Exercise in the heat: Effects of dinitrophenol administration

1. 1.|Dinitrophenol (DNP) was administered to rats in two equal dosages (20 mg/kg, 30 min interval); the second injection was followed immediately by exercise (9.14 m/min) in the heat (30°C) or at room temperature (21°C).

2. 2.|At 21°C control (saline-treated) rats manifested a mean endurance of 94 min which was reduced to 32 min among DNP-treated animals.

3. 3.|At 30°C, control rats ran for 65 min (δT_re/min = 0.05°C) while DNP-treated animals had a mean endurance of only 12 min (δT_re/min = 0.22°C).

4. 4.|DNP-treated rats (30°C) manifested no decrements in tail-skin heat loss (δT_sk/min = 0.17°C vs 0.10°C) or saliva secretion (0.78 g/min, DNP vs. 0.19 g/min, control) for their brief treadmill duration.

5. 5.|The increased metabolic heat production of DNP severely reduced performance.

Cardiac output and oxygen uptake kinetics at the onset and offset of exercise

1. 1. The aim of the present study is to assess the relationship between rapidity of oxygen uptake (V_O2 and cardiac output (Q) kinetics at the transient phase of the onset and offset of exercise.

2. 2. Five healthy male subjects performed multiple rest-exercise-recovery transitions on an electrically braked ergometer, work rate was 50, 75, or 100 W for 6 min, respectively.

3. 3. V_O2 was obtained by a breath-by-breath method, and Q was measured by an impedance method during normal breath, using an ensemble averaged method.

4. 4. On transition from rest to exercise, V_O2 rapidly increased as phase I with a time constant of 7.0–7.8 s. Q also showed a similar rapid increment with a time constant of 6.3–6.8 s in phase I.

5. 5. In this phase I, V_O2 increased approx. 42–68% of steady state value and Q increased 71–84%. Thereafter, V_O2 and Q increased monoexponentially up to steady state with a time constant of 26.7–32.3 and 23.7–34.4 s, respectively.

6. 6. During recovery, V_O2 (with a time constant of 35.7–38.1 s and time delay (TD) of −1 to −2 s), while Q remained to sustain the value of steady state exercise with a couple of time delay (TD = 2–7 s), and thereafter decreased monoexponentially (with a time constant of 18.9–31.6 s).

7. 7. The stroke volume showed the similar behavior to the Q kinetics after exercise, while heart rate rapidly decreased (time constant = 10.6–21.2 s).

8. 8. It is suggested that the delayed Q kinetics after exercise might be attributable to the sustained level of venous return and that Q kinetics is not linked with V_O2 kinetics after exercise.

Heat stress and age: Skin blood flow and body temperature

1. 1. The ability to increase skin blood flow is an important mechanism for transferring heat from the body core to the skin for dissipation.

2. 2. During exercise, skin blood flow is typically 20–40% lower in men and women aged 55 and over (compared with 20–30 years old) at a given body core temperature. Yet criterion measures of heat tolerance (changes in core temperature, heat storage) often show minimal or no age-related alterations. From a series of studies conducted in our laboratory over the past 5 years, the following conclusions can be drawn.

3. 3. When fit healthy older subjects are matched with younger subjects of the same gender, size and body composition, V_O2max, acclimation state, and hydration level, age-related differences in skin blood flow are evident. However, these differences often do not translate into “poorer” heat tolerance or higher core temperatures.

4. 4. The larger core-to-skin thermal gradient maintained by the older individuals allows for effective heat transfer at lower skin blood flows.

5. 5. Furthermore, there is an increased coefficient of variation for thermoregulatory response variables with increasing age.

6. 6. Despite differences in the mechanisms underlying thermoregulation, true thermal tolerance is less a function of chronological age than of functional capacity and physiological health status.

7. 7. While this conclusion is based primarily on cross-sectional studies, it is supported by the results of more recent studies using multiple regression analyses.

8. 8. Implicit in this conclusion is the notion that thermal tolerance, at any age, is a modifiable individual characteristic.

Thermal gradients in the oesophagus of man during exercise and passive warming

1. 1.|Oesophageal temperature (T_es) has been recorded at four vertical levels in the oesophagus of human subjects during exercise and during passive body heating.

2. 2.|The temperature increased with depth.

3. 3.|The rate of increase in T_es during exercise was greatest at the level of the diaphragm.

4. 4.|During passive heating of the body T_es increased most rapidly, and with shortest latency time, at the level adjacent to the left atrium of the heart.

5. 5.|During exercise, when breathing is deeper than at rest, T_es should be measured at a deeper level than that which is used during passive heating.

Muscle temperature and muscle metabolism during short-term exercise in the goat

1. 1.|External heat exchangers acting on lower aortal blood temperature were used to dissociate hindleg muscle temperature (T_hlm) from general internal temperature (T_int) during short-term exercise of moderate intensity.

2. 2.|In series 1 39°C T_hlm was combined with 40.6°C T_int, and in series II 42°C T_hlm was combined with 39.8°C T_int.

3. 3.|At constant work rates, the 3°C difference in muscle temperature did not result in significantly different concentrations of muscle metabolites.

4. 4.|It is concluded that high local muscle temperature without general hyperthermia does not influence muscle metabolism during short-term moderate excercise.

Characteristics of the temperature regulation system in the human body

1. 1. To study a complex biological system such as human temperature regulation, it is necessary to consider both physiological experiments and theoretical analysis.

2. 2. This paper presents the characteristics of this temperature regulation system obtained from a mathematical model, together with experimental data and the influence of exercise and clothing.

3. 3. The experimental results showed a good agreement with the theoretical results.

Energy expenditure and metabolic adaptation during winter dormancy in the lizard Lacerta vivipara Jacquin

1. 1.Laceria vivipara were hibernated from October to March. Respiration rates were measured at various times during this period and compared with respiration rates of lizards at the same temperatures in July.

2. 2.Rates of respiration at 10°C soon after entry into hibernation and towards the end of the dormant period did not differ significantly from rates at 10°C in July.

3. 3.After several weeks in hibernation at 10°C a depression of metabolism occurred which produced acclimated respiration rates significantly lowe than 10°C rates measured at other times of year. This is interpreted as a probable case of negative metabolic compensation to temperature (inverse acclimation).

4. 4.No difference in respiration rates at 5°C could be detected between dormant and summer lizards.

5. 5.Energy expenditure during winter dormancy accounts for approximately 5% of the energy assimilated annually from food. Inverse acclimation at 10°C effects an energy saving amounting to about 35% of the total dormancy expenditure.

A relationship between heat load and plasma enzyme concentration

1. 1. The sensitivity of serum enzyme levels as indicators of tissue damage is less well established in the prodromal period of heatstroke, especially for sub-lethal stress conditions.

2. 2. Anaesthetized rats were exposed to two different sets of thermal conditions.

3. 3. Plasma levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), creatine kinase (CK) and lactate dehydrogenase (LD) were assayed in each group upon termination of stress, 6 h post-stress and 24 h post-stress.

4. 4. The tissue “damage” sustained was mild to moderate and completely reversible.

5. 5. The rate of rise in body temperature may constitute an important factor in the ultimate pathology.

6. 6. CK proved to be the most sensitive parameter of tissue “damage”.

An experimental study of effects of low-level sound in our daily life on a mental task

1. 1. It is often reported that any sound from the neighborhood disturbs one's reading or study, even though it is at a low level.

2. 2. This study was done to clarify the mechanism by which the low level sound in our daily life exerts an influence upon mental tasks.

3. 3. Two experiments were carried out, one by an ordinary, and the other by a social psychological test. In both, a random number generation test was applied as the mental exercise. The levels of presented sounds in each condition were 34–45 dBA in Leq.

4. 4. One of various conditions was in conformity with a setting of“low level noise”, where existence of low level sound is not recognized as an inevitable phenomenon but perceived as the noise.

5. 5. The quality of performance tends to be worse, though the quantitative side can be maintained.

Exercise performance of normothermic and hyperthermic rats: Effect of warm rearing

1. 1.|Hypothalamic and rectal temperatures were recorded in 8 warm-reared (wr) and 12 control rats. Rats ran to exhaustion at a constant speed of 1.5 km h⁻¹ but at a variable ambient temperature adjusted to stabilize their hypothalamic temperature at 38.0°C (normothermia) or 41.0°C (hyperthermia). Blood lactate concentrations were determined before and after exercise.

2. 2.|Exercise caused exhaustion in normothermic control rats after 62.08 ± 5.43 min and in wr rats after 29.64 ± 2.09 min.

3. 3.|Hyperthermia shortened to one half (to 12.24 ± 1.36 min) and to one fourth (to 16.15 ± 1.20 min) the endurance time in wr and control rats, respectively.

4. 4.|There were no correlations between lactate concentraion and hyperthermia or endurance time.

5. 5.|In conclusion, in rats and other animals which have safe refuges, hyperthermia interferes with the ability to continue exercising.

Cardiovascular and thermoregulatory responses to repeated anticholinesterase administration

1. 1.|Pyridostigmine administration decreased resting heart rate by 11 ± 7 beats/min and resting oesophageal temperature by 0.23 ± 12°C after 50 h (P < 0.05). In addition, red blood cell cholinesterase activity was decreased an average of 43 ± 7% after 50 h of pyridostigmine treatment.

2. 2.|The lower heart rates and core temperatures at rest were continued during high intensity exercise in a 35°C environment. Whole body sweating was 12 ± 18% higher (P = 0.20) during exercise in the heat after 50 h of pyridostigmine treatment.

3. 3.|Repeated anticholinesterase administration had little effect on cardiovascular and thermoregulatory responses during high intensity exercise.

A pilot experiment on a method for evaluating acceptability of a daylit luminous environment

1. 1. We propose a hierarchical model as a hypothesis to evaluate comfort in lighting environments.

2. 2. The model consists of physical quantities such as stimuli, and visual sensations as the first response, and then overall evaluation.

3. 3. A pilot experiment in a side-lit classroom usng 147 subjects was made to examine this model.

4. 4. It was found that in the side-lit classroom the most effective answers for discrimination between “acceptable” and “not acceptable” were “the surface of desk was not considered dark” and “not to experience any reflectance of lighting on the sheet of paper on which they wrote”.

5. 5. Moreover all of the effective items relate to the task area, namely desk and blackboard, and this meant that subjects gave priority to workability in the classroom.

Investigations on the surveys of office environments and the total evaluation method—IAQ-Index

1. 1. A comprehensive study was made to establish evaluation methods for better office environments.

2. 2. In our study, measurements of thermal, acoustic, lighting, airflow and air quality conditions in indoor environments were made as well as questionnaire to the occupants on the evaluations of indoor environments and the feeling of fatigue.

3. 3. We also made an attempt to rate the evaluation value based on concepts and standards to evaluate totally office environments in a view point of “the office environments where people can work healthy and vigorously”. The evaluation values were called IAQ-index.

Effect of warm rearing on temperature regulation in resting and exercising rats

1. 1.|Hypothalamic and rectal temperatures were recorded in 8 warm-reared (wr) and in 12 warm-acclimated control rats during resting in the heat and during 30 min running under thermoneutral conditions.

2. 2.|Brain and body temperatures of wr rats were significantly higher (P < 0.001) than control rats, both in normothermia as well as in hyperthermia; at rest, and also during exercise.

3. 3.|Warm-reared rats were more tolerant to heat.

4. 4.|During normothermia a weak selective brain cooling was present in control but absent in wr rats. During hyperthermia, however, the cooling intensified in control and occurred in wr rats.

5. 5.|The main strategy of adaptation to heat in wr rats is an upward resetting of the temperature set-point and increased passivity.

Effect of fiber type and fabric moisture content on the hydration state of human stratum corneum

1. 1. The purpose of this study was to determine the effect of fiber type and fabric moisture content on SC hydration.

2. 2. Using three similarly constructed fabrics, six fabric type/moisture content combinations were selected.

3. 3. Fabric swatches were placed on both “normal” and “hydrated” volar forearm skin of five subjects for a specified period, then removed.

4. 4. Two minutes after removal, evaporative water loss (EWL) and skin temperature were measured.

5. 5. Data were analyzed using analyses of variance and Bonferroni t-tests.

6. 6. For normal skin, SC hydration generally increased as fabric moisture content increased. SC was significantly drier after being in contact with cotton swatches at regain than at the two moisture content levels above regain, and also under polyester swatches.

7. 7. For hydrated skin, hydration state was significantly lower under the cotton swatch at regain than at 38.6% moisture content or at saturation, but was not significantly different under the polyester swatch at regain or at saturation.

The effects of wind and thermal radiation on thermal responses during rest and exercise in a cold environment

1. 1. The purpose of this study was to investigate the effects of thermal radiation and wind on thermal responses at rest and during exercise in a cold environment.

2. 2. The experimental conditions were radiation and wind (R + W), no radiation and wind (W), radiation and no wind (R), no radiation and no wind (C).

3. 3. The air temperature was −5°C. Thermal radiation was 360 W/m². Air velocities were 0.76, 1.73 and 2.8 m/s. Rectal and skin temperatures, heart rate and oxygen consumption were recorded. Thermal and comfort sensations were questioned.

4. 4. There are no significant effects of thermal radiation and wind on the physiological responses except the mean skin temperature. There are significant effects on the mean skin temperature (P < 0.01) and thermal sensation (P < 0.05).

The combined effects of ambient temperature and enforced sustained swimming activity on body temperatures of arctic charr (Salvelinus alpinus L.)

1. 1.|The difference between tissue temperatures and ambient water temperatures (ΔT) of the ectothermic Arctic charr (Salvelinus alpinus L.) ranged between 0.2 and 0.6°C.

2. 2.|For fish held at 5.7°C there were no significant differences in ΔT of exercising fish and those of controls.

3. 3.|By contrast, for fish held at 1.7°C sustained exercise led to a significant increase in ΔT of all body compartments compared with fish held in standing water (controls).

4. 4.|It is suggested that Arctic charr are capable of a limited control of metabolic heat exchange between body compartments and surrounding water when subjected to sustained exercise and ambient temperatures <2°C.

Special work-wear and protective clothing for Indian furnace workers

1. 1. In the present study two new, ergonomically designed, low-cost prototypes of protective work-wear for furnace workers of five hot metal and three glass factories in West Bengal were developed and evaluated on the basis of objective and subjective assessments.

2. 2. The objective assessments included the thermal data of the workplaces during summer and winter months, data on accidents and workers' physiological responses such as pulse rates, core and skin temperatures and sweat loss during work with the existing as well as work-wear. The subjective assessments were from questionnaires on the merits and demerits of the existing and new work-wear and the comfort votes.

3. 3. The study recommended the use of ergonomically designed, low-cost, washable, ventilated, vapour permeable, flame-retardant, radiant-heat-reflecting type special work clothing (Prototype No.II) by the workers to reduce the heat stress, accident risks and the physiological costs and to increase efficiency and productivity.