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1.
Sci Rep ; 14(1): 14429, 2024 06 23.
Article in English | MEDLINE | ID: mdl-38910179

ABSTRACT

Detecting emotions from facial images is difficult because facial expressions can vary significantly. Previous research on using deep learning models to classify emotions from facial images has been carried out on various datasets that contain a limited range of expressions. This study expands the use of deep learning for facial emotion recognition (FER) based on Emognition dataset that includes ten target emotions: amusement, awe, enthusiasm, liking, surprise, anger, disgust, fear, sadness, and neutral. A series of data preprocessing was carried out to convert video data into images and augment the data. This study proposes Convolutional Neural Network (CNN) models built through two approaches, which are transfer learning (fine-tuned) with pre-trained models of Inception-V3 and MobileNet-V2 and building from scratch using the Taguchi method to find robust combination of hyperparameters setting. The proposed model demonstrated favorable performance over a series of experimental processes with an accuracy and an average F1-score of 96% and 0.95, respectively, on the test data.


Subject(s)
Deep Learning , Emotions , Facial Expression , Neural Networks, Computer , Humans , Emotions/physiology , Image Processing, Computer-Assisted/methods , Facial Recognition/physiology , Female , Male
2.
J Commun Healthc ; : 1-11, 2023 Dec 27.
Article in English | MEDLINE | ID: mdl-38149652

ABSTRACT

BACKGROUND: The use of social media as a platform to access news and information has the potential to lead to the spread of fake news in Indonesia. This study aims to (1) understand the trust characteristics in information of Indonesians during COVID-19; (2) identify Indonesians' ability to detect COVID-19 fake news; and (3) analyze the relationship between people's trust characteristics in information with regard to COVID-19 information and their ability to detect fake news. METHOD: An online survey was conducted with 751 Indonesians who use social media to access information about COVID-19. Cultural theory is used to categorize people's trust characteristics in information, while signal detection theory is employed to identify people's ability to discriminate between fake and real news. RESULTS: The results showed that 61% of respondents were categorized as having hierarchy trust characteristics. Concerning the detectability of fake news, most respondents could discriminate between fake and real news. Lastly, there was a relationship between trust characteristics in information and bias tendencies in detecting fake news. CONCLUSIONS: The respondents have hierarchy trust characteristics, indicating they trusted government information related to COVID-19 issues. The respondents also have high ability to discriminate between fake and real news, even though they tended to miss more errors than identify false alarms when detecting fake news. The findings showed that respondents who had hierarchy and egalitarian characteristics tended to perceive real news as fake news and had a better ability to distinguish fake news compared to other trust characteristics in information.

3.
J Physiol Anthropol ; 41(1): 27, 2022 Jul 14.
Article in English | MEDLINE | ID: mdl-35836266

ABSTRACT

This review mainly aimed to introduce the findings of research projects comparing the responses of tropical and temperate indigenes to heat. From a questionnaire survey on thermal sensation and comfort of Indonesians and Japanese, we found that the thermal descriptor "cool" in tropical indigenes connotes a thermally comfortable feeling, suggesting that linguistic heat acclimatization exists on a cognitive level. Ten male students born and raised in Malaysia were invited to Fukuoka, Japan, and compared their responses with 10 Japanese male students with matched physical fitness and morphological characteristics. Cutaneous thermal sensitivity: The sensitivities were measured at 28 °C. The forehead warm sensitivity was significantly blunted in Malaysians. The less sensitivity to the warmth of tropical indigenes is advantageous in respect to withstanding heat stress with less discomfort and a greater ability to work in hot climates. Passive heat stress: Thermoregulatory responses, especially sweating, were investigated, during the lower leg hot bathing (42 °C for 60 min). The rectal temperature at rest was higher in Malaysians and increased smaller during immersion. There was no significant difference in the total amount of sweating between the two groups, while the local sweating on the forehead and thighs was lesser in Malaysians, suggesting distribution of sweating was different from Japanese. Exercise: Malaysian showed a significantly smaller increase in their rectal temperature during 55% maximal exercise for 60 min in heat (32 °C 70% relative humidity), even with a similar sweating and skin blood flow response in Japanese. The better heat tolerance in Malaysians could be explained by the greater convective heat transfer from the body core to the skin due to the greater core-to-skin temperature gradient. In addition, when they were hydrated, Malaysian participants showed better body fluid regulation with smaller reduction in plasma volume at the end of the exercise compared to the non-hydrated condition, whereas Japanese showed no difference between hydration conditions. We further investigated the de-acclimatization of heat adaptation by longitudinal observation on the heat tolerance of international students who had moved from tropical areas to Fukuoka for several years.


Subject(s)
Body Temperature Regulation , Hot Temperature , Acclimatization/physiology , Body Temperature/physiology , Body Temperature Regulation/physiology , Climate , Humans , Male , Sweating
4.
Work ; 71(1): 65-78, 2022.
Article in English | MEDLINE | ID: mdl-34924428

ABSTRACT

BACKGROUND: The COVID-19 pandemic has increased some psychosocial risks which may aggravate the development of musculoskeletal disorders (MSDs) and reduced psychological well-being, two leading global occupational health problems. OBJECTIVE: This study aims to investigate whether an employee's psychological well-being mediates the relationship between the psychosocial factors (job strain, work-life balance, and job security) and the prevalence of musculoskeletal pain in the Indonesian general working population during the pandemic. METHODS: A cross-sectional study design was employed using an online questionnaire. A total of 406 from 465 respondents were included in the final analysis. RESULTS: It was found that 73.9% of respondents suffered from upper body part pain, 25.15% from low back pain, and 39.7% reported pain in the lower limb. Process Macro Model 4 analysis showed the significant role of well-being as a mediator in the association between work-life balance and the odds of experiencing the upper body and low back pains. However, neither the direct nor mediating effect on the relationship between job strain or job security and any musculoskeletal pains were observed. These findings suggest that specific psychosocial factors may be more relevant to be investigated in the particular context. CONCLUSION: The use of a mediation model was able to link work-life balance to musculoskeletal complaints through well-being states in the context of the pandemic. Organizations need to mitigate poor well-being triggered by psychosocial stressors which could affect physical complaints to maintain employee's health and productivity.


Subject(s)
COVID-19 , Musculoskeletal Diseases , Musculoskeletal Pain , Occupational Diseases , Cross-Sectional Studies , Humans , Musculoskeletal Diseases/complications , Musculoskeletal Diseases/epidemiology , Musculoskeletal Pain/epidemiology , Musculoskeletal Pain/etiology , Occupational Diseases/epidemiology , Pandemics , Risk Factors , SARS-CoV-2 , Surveys and Questionnaires
5.
J Physiol Anthropol ; 36(1): 28, 2017 Jun 23.
Article in English | MEDLINE | ID: mdl-28645314

ABSTRACT

BACKGROUND: Human adaptability to cold environment has been focused on in the physiological anthropology and related research area. Concerning the human acclimatization process in the natural climate, it is necessary to conduct a research assessing comprehensive effect of cold environment and physical activities in cold. This study investigated the effect of cold water immersion on the exercise performance and neuromuscular function during maximal and submaximal isometric knee extension. METHODS: Nine healthy males participated in this study. They performed maximal and submaximal (20, 40, and 60% maximal load) isometric knee extension pre- and post-immersion in 23, 26, and 34 °C water. The muscle activity of the rectus femoris (RF) and vastus lateralis (VL) was measured using surface electromyography (EMG). The percentages of the maximum voluntary contraction (%MVC) and mean power frequency (MPF) of EMG data were analyzed. RESULTS: The post-immersion maximal force was significantly lower in 23 °C than in 26 and 34 °C conditions (P < 0.05). The post-immersion %MVC of RF was significantly higher than pre-immersion during 60% maximal exercise in 23 and 26 °C conditions (P < 0.05). In the VL, the post-immersion %MVC was significantly higher than pre-immersion in 23 and 26 °C conditions during 20% maximal exercise and in 26 °C at 40 and 60% maximal intensities (P < 0.05). The post-immersion %MVC of VL was significantly higher in 26 °C than in 34 °C at 20 and 60% maximal load (P < 0.05). The post-immersion MPF of RF during 20% maximal intensity was significantly lower in 23 °C than in 26 and 34 °C conditions (P < 0.05), and significantly different between three water temperature conditions at 40 and 60% maximal intensities (P < 0.05). The post-immersion MPF of VL during three submaximal trials were significantly lower in 23 and 26 °C than in 34 °C conditions (P < 0.05). CONCLUSIONS: The lower shift of EMG frequency would be connected with the decrease in the nerve and muscle fibers conduction velocity. To compensate for the impairment of each muscle fibers function, more muscle fibers might be recruited to maintain the working load. This might result in the greater amplitude of EMG after the cold immersion.


Subject(s)
Electromyography , Hypothermia, Induced , Knee/physiology , Muscle Contraction/physiology , Muscle, Skeletal/physiology , Adult , Cold Temperature , Humans , Male , Young Adult
6.
Int J Biometeorol ; 61(7): 1261-1267, 2017 Jul.
Article in English | MEDLINE | ID: mdl-28083707

ABSTRACT

This study aimed to investigate the effect of repeated cooling of forearm muscle on adaptation in skeletal muscle metabolism. It is hypothesized that repeated decreases of muscle temperature would increase the oxygen consumption in hypothermic skeletal muscle. Sixteen healthy males participated in this study. Their right forearm muscles were locally cooled to 25 °C by cooling pads attached to the skin. This local cooling was repeated eight times on separate days for eight participants (experimental group), whereas eight controls received no cold exposure. To evaluate adaptation in skeletal muscle metabolism, a local cooling test was conducted before and after the repeated cooling period. Change in oxy-hemoglobin content in the flexor digitorum at rest and during a 25-s isometric handgrip (10% maximal voluntary construction) was measured using near-infrared spectroscopy at every 2 °C reduction in forearm muscle temperature. The arterial blood flow was occluded for 15 s by upper arm cuff inflation at rest and during the isometric handgrip. The oxygen consumption in the flexor digitorum muscle was evaluated by a slope of the oxy-hemoglobin change during the arterial occlusion. In the experimental group, resting oxygen consumption in skeletal muscle did not show any difference between pre- and post-intervention, whereas muscle oxygen consumption during the isometric handgrip was significantly higher in post-intervention than in pre-test from thermoneutral baseline to 31 °C muscle temperature (P < 0.05). This result indicated that repeated local muscle cooling might facilitate oxidative metabolism in the skeletal muscle. In summary, skeletal muscle metabolism during submaximal isometric handgrip was facilitated after repeated local muscle cooling.


Subject(s)
Cold Temperature , Muscle, Skeletal/metabolism , Adaptation, Physiological , Adult , Forearm/physiology , Hand Strength , Humans , Male , Oxygen Consumption , Regional Blood Flow , Skin/blood supply , Skin Temperature , Young Adult
7.
J Physiol Anthropol ; 36(1): 8, 2017 Jan 05.
Article in English | MEDLINE | ID: mdl-28057082

ABSTRACT

BACKGROUND: Heat acclimatization studies have reported that tropical natives have better physiological function to tolerate heat exposure compared to those from temperate natives, in which may result in a better ability to show a better resistance to performance losses during heat stress. In this study, we investigate whether the degree of heat acclimatization affects cognitive abilities during heat exposure by comparing heat acclimatization level of subjects from Southeast Asia and temperate natives from Japan. METHODS: Eleven tropical males from Southeast Asia and ten temperate males from Japan participated in this study and performed two types of cognitive task: short-term memory test and mental arithmetic test, under control and passive heat exposure conditions. Passive heat condition was stimulated through leg immersion protocol by immersing subjects' lower legs into a hot water maintained at 42 °C in a chamber controlled at 28 °C air temperature and 50% relative humidity. RESULTS: The results show that the subjects in tropical group, who had smaller increase of rectal temperature, did not show any performance losses in both cognitive tests during heat exposure, while for Japanese group, there was performance decrement in mental arithmetic test during heat exposure (P < 0.05). We also found that the subjects in both tropical and Japanese groups tried to maintain their performance by increasing oxyhemoglobin in their prefrontal cortex area during performing the tasks during heat exposure. In addition, the subjects in the Japanese group showed higher increase of oxyhemoglobin when they performed the tasks during heat exposure than those when they performed the tasks in control condition (P < 0.05), while the subjects in tropical group did not show any differences in oxyhemoglobin during task performance between control and heating conditions. CONCLUSIONS: In addition to a better ability to maintain their homeostasis during heat exposure, tropical natives from Southeast Asia showed better resistance to performance loss during heat exposure in comparison with temperate natives from Japan. The tropical natives also showed smaller increase of oxyhemoglobin indicating less cognitive effort to maintain performance.


Subject(s)
Acclimatization/physiology , Cognition/physiology , Hot Temperature , Adult , Asia, Southeastern , Hemodynamics/physiology , Humans , Japan , Male , Skin Temperature/physiology , Task Performance and Analysis , Young Adult
8.
J Physiol Anthropol ; 33: 5, 2014 Feb 04.
Article in English | MEDLINE | ID: mdl-24490869

ABSTRACT

BACKGROUND: This study investigated the effect of hydration differences on body fluid and temperature regulation between tropical and temperate indigenes exercising in the heat. METHODS: Ten Japanese and ten Malaysian males with matched physical characteristics (height, body weight, and peak oxygen consumption) participated in this study. Participants performed exercise for 60 min at 55% peak oxygen uptake followed by a 30-min recovery at 32°C and 70% relative air humidity with hydration (4 times each, 3 mL per kg body weight, 37°C) or without hydration. Rectal temperature, skin temperature, heart rate, skin blood flow, and blood pressure were measured continuously. The percentage of body weight loss and total sweat loss were calculated from body weight measurements. The percentage change in plasma volume was estimated from hemoglobin concentration and hematocrit. RESULTS: Malaysian participants had a significantly lower rectal temperature, a smaller reduction in plasma volume, and a lower heart rate in the hydrated condition than in the non-hydrated condition at the end of exercise (P <0.05), whereas Japanese participants showed no difference between the two hydration conditions. Hydration induced a greater total sweat loss in both groups (P <0.05), and the percentage of body weight loss in hydrated Malaysians was significantly less than in hydrated Japanese (P <0.05). A significant interaction between groups and hydration conditions was observed for the percentage of mean cutaneous vascular conductance during exercise relative to baseline (P <0.05). CONCLUSIONS: The smaller reduction in plasma volume and percentage body weight loss in hydrated Malaysians indicated an advantage in body fluid regulation. This may enable Malaysians to reserve more blood for circulation and heat dissipation and thereby maintain lower rectal temperatures in a hydrated condition.


Subject(s)
Asian People/statistics & numerical data , Body Fluids/physiology , Body Temperature Regulation/physiology , Dehydration/epidemiology , Exercise/physiology , Adult , Dehydration/physiopathology , Hot Temperature , Humans , Humidity , Japan , Malaysia , Male , Sodium/blood , Thirst/physiology , Young Adult
9.
Int J Biometeorol ; 57(4): 557-67, 2013 Jul.
Article in English | MEDLINE | ID: mdl-22898999

ABSTRACT

This study investigated the effects of passive heat exposure on pre-frontal cortex oxygenation and cognitive functioning, specifically to examine whether the change in pre-frontal cortex oxygenation coincided with cognitive functioning during heat exposure. Eleven male students who participated in this study immersed their lower legs to the knees in three different water temperatures, 38 °C, 40 °C, and 42 °C water in an air temperature of 28 º C and 50 % relative humidity for 60 min. After 45 min of leg immersion they performed cognitive functioning tasks assessing their short-term memory while immersing their lower legs. There were higher rectal temperature (P < 0.05) and higher increase of oxyhemoglobin in both left (P < 0.05) and right (P < 0.05) pre-frontal cortex at the final stage of 45-min leg immersion in the 42 °C condition with unaltered tissue oxygenation index among the three conditions (P > 0.05). No statistical difference in cognitive functioning among the three conditions was observed with a higher increase of oxyhemoglobin during the cognitive functioning in the 42 °C condition for the left (P = 0.05) and right (P < 0.05) pre-frontal cortex. The findings of this study suggest, first, passive heat exposure increases oxygen delivery in the pre-frontal cortex to maintain pre-frontal cortex oxygenation; second, there is no evidence of passive heat exposure in cognitive functioning in this study; and third, the greater increases of oxyhemoglobin in the pre-frontal cortex during cognitive functioning at the hottest condition suggests a recruitment of available neural resources or greater effort to maintain the same performance at the same level as when they felt thermally comfortable.


Subject(s)
Cognition/physiology , Hot Temperature , Memory, Short-Term/physiology , Oxyhemoglobins/metabolism , Prefrontal Cortex/metabolism , Adult , Body Temperature , Humans , Immersion , Leg , Male , Oxygen/metabolism , Water , Young Adult
10.
J Physiol Anthropol ; 31: 25, 2012 Sep 13.
Article in English | MEDLINE | ID: mdl-22974339

ABSTRACT

BACKGROUND: In this study, we investigated the effects of duration of stay in a temperate area on the thermoregulatory responses to passive heat exposure of residents from tropical areas, particularly to clarify whether they would lose their heat tolerance during passive heat exposure through residence in a temperate country, Japan. METHODS: We enrolled 12 males (mean ± SE age 25.7 ± 1.3 years) from south-east Asian countries who had resided in Japan for a mean of 24.5 ± 5.04 months, and 12 Japanese males (age 24.1 ± 0.9 years). Passive heat exposure was induced through leg immersion in hot water (42°C) for 60 minutes under conditions of 28°C air temperature and 50% relative humidity. RESULTS: Compared with the Japanese group, the tropical group displayed a higher pre-exposure rectal temperature (P < 0.01) and a smaller increase in rectal temperature during 60 minutes of leg immersion (P = 0.03). Additionally, the tropical group showed a tendency towards a lower total sweat rate (P = 0.06) and lower local sweat rate on the forehead (P = 0.07). The tropical group also had a significantly longer sweating onset time on the upper back (P = 0.04) compared with the Japanese groups. The tropical group who stayed in Japan for > 23 months sweated earlier on the forehead and upper back than those who stayed in Japan < 11 months (P < 0.01 and P = 0.03 for the forehead and upper back, respectively). There was a positive correlation between duration of stay in Japan and total sweat rate (r = 0.58, P <0.05), and negative correlations between duration of stay and sweating onset time on the forehead (r = -0.73, P = 0.01) and on the upper back (r = -0.66, P = 0.02). Other physiological indices measured in this study did not show any difference between the subjects in the tropical group who had lived in Japan for a shorter time and those who had lived there for a longer time. CONCLUSIONS: We conclude that the nature of heat acclimatization of the sweating responses to passive heat exposure that are acquired from long-term heat acclimatization is decayed by a stay in a temperate area, as shown by the subjects in our tropical group. We did not find any evidence of a decay in the other physiological indices, indicating that heat tolerance acquired from long-term heat acclimatization is not completely diminished through residence in a temperate area for less than 4 years, although some aspects of this heat tolerance may be decayed.


Subject(s)
Acclimatization/physiology , Body Temperature Regulation/physiology , Adult , Asia, Southeastern/ethnology , Body Temperature/physiology , Emigrants and Immigrants , Hot Temperature , Humans , Japan , Male , Sweating/physiology
11.
Int J Biometeorol ; 56(6): 1055-64, 2012 Nov.
Article in English | MEDLINE | ID: mdl-22290685

ABSTRACT

The purpose of this study was to explore whether there is evidence of heat acclimatization in the words used to express thermal sensation. A total of 458 urban Japanese and 601 Indonesians participated in a questionnaire. In addition, in a preliminary survey, 39 native English speakers in the UK participated. Our results showed that (1) for Indonesians, the closest thermal descriptor of a feeling of thermal comfort was 'cool' (75%) followed by 'slightly cool' (7%), 'slightly cold' (5%) and 'cold' (5%), while Japanese responses were distributed uniformly among descriptors 'cool', 'slightly cool', 'neither', 'slightly warm', and 'warm'; (2) the closest thermal descriptors of a feeling of discomfort for Indonesians were less affected by individual thermal susceptibility (vulnerability) than those for Japanese; (3) in the cases where 'cool' and 'slightly cold' were imagined in the mind, the descriptors were cognized as a thermal comfortable feeling by 97% and 57% of Indonesians, respectively; (4) the most frequently voted choice endorsing hot weather was 'higher than 32°C' for Indonesians and 'higher than 29°C' for Japanese respondents; for cold weather, 'lower than 15°C' for Japanese and 'lower than 20°C' for Indonesians. In summary, the descriptor 'cool' in Indonesians connotes a thermally comfortable feeling, but the inter-zone between hot and cold weather that was judged in the mind showed a upward shift when compared to that of Japanese. It is suggested that linguistic heat acclimatization exists on a cognitive level for Indonesians and is preserved in the words of thermal descriptors.


Subject(s)
Acclimatization/physiology , Body Temperature Regulation/physiology , Language , Semantics , Temperature , Thermosensing/physiology , Female , Humans , Indonesia , Japan , Male , Surveys and Questionnaires , United Kingdom , Young Adult
12.
Int J Biometeorol ; 56(4): 631-7, 2012 Jul.
Article in English | MEDLINE | ID: mdl-21695574

ABSTRACT

There are several types of cold adaptation based on the alteration of thermoregulatory response. It has been thought that the temperature of repeated cold exposures during the adaptation period is one of the factors affecting the type of cold adaptation developed. This study tested the hypothesis that repeated mild cold immersions would induce an insulative cold adaptation but would not alter the metabolic response. Seven healthy male participants were immersed to their xiphoid process level repeatedly in 26°C water for 60 min, 3 days every week, for 4 weeks. During the first and last exposure of this cold acclimation period, the participants underwent body immersion tests measuring their thermoregulatory responses to cold. Separately, they conducted finger immersion into 5°C water for 30 min to assess their cold-induced vasodilation (CIVD) response before and after cold acclimation. During the immersion to xiphoid process, participants showed significantly lower mean skin temperature and skin blood flow in the forearm post-acclimation, while no adaptation was observed in the metabolic response. Additionally, blunted CIVD responses were observed after cold acclimation. From these results, it was considered that the participants showed an insulative-type of cold acclimation after the repeated mild cold immersions. The major finding of this study was the acceptance of the hypothesis that repeated mild cold immersion was sufficient to induce insulative cold adaptation but did not alter the metabolic response. It is suggested that the adaptation in the thermoregulatory response is specific to the response which is repeatedly stimulated during the adaptation process.


Subject(s)
Acclimatization/physiology , Cold Temperature , Adult , Body Temperature , Humans , Male , Regional Blood Flow , Skin/blood supply , Vasoconstriction , Water , Young Adult
13.
Eur J Appl Physiol ; 111(12): 2895-905, 2011 Dec.
Article in English | MEDLINE | ID: mdl-21437607

ABSTRACT

For the coherent understanding of heat acclimatization in tropical natives, we compared ethnic differences between tropical and temperate natives during resting, passive and active heating conditions. Experimental protocols included: (1) a resting condition (an air temperature of 28°C with 50% RH), (2) a passive heating condition (28°C with 50% RH; leg immersion in a hot tub at a water temperature of 42°C), and (3) an active heating condition (32°C with 70% RH; a bicycle exercise). Morphologically and physically matched tropical natives (ten Malaysian males, MY) and temperate natives (ten Japanese males, JP) participated in all three trials. The results saw that: tropical natives had a higher resting rectal temperature and lower hand and foot temperatures at rest, smaller rise of rectal temperature and greater temperature rise in bodily extremities, and a lower sensation of thirst during passive and active heating than the matched temperate natives. It is suggested that tropical natives' homeostasis during heating is effectively controlled with the improved stability in internal body temperature and the increased capability of vascular circulation in extremities, with a lower thirst sensation. The enhanced stability of internal body temperature and the extended thermoregulatory capability of vascular circulation in the extremities of tropical natives can be interpreted as an interactive change to accomplish a thermal dynamic equilibrium in hot environments. These heat adaptive traits were explained by Wilder's law of initial value and Werner's process and controller adaptation model.


Subject(s)
Body Temperature Regulation/physiology , Body Temperature/physiology , Exercise/physiology , Rest/physiology , Adaptation, Physiological/physiology , Adult , Blood Circulation/physiology , Body Mass Index , Ethnicity , Hot Temperature , Humans , Japan , Malaysia , Male , Skin Temperature , Thermodynamics , Young Adult
14.
Int J Biometeorol ; 55(4): 509-17, 2011 Jul.
Article in English | MEDLINE | ID: mdl-20949285

ABSTRACT

This study investigated the differences in heat dissipation response to intense heat stress during exercise in hot and humid environments between tropical and temperate indigenes with matched physical characteristics. Ten Japanese (JP) and ten Malaysian (MY) males participated in this study. Subjects performed exercise for 60 min at 55% peak oxygen uptake in 32°C air with 70% relative humidity, followed by 30 min recovery. The increase in rectal temperature (T(re)) was smaller in MY during exercise compared to JP. The local sweat rate and total body mass loss were similar in both groups. Both skin blood flow and mean skin temperature was lower in MY compared to JP. A significantly greater increase in hand skin temperature was observed in MY during exercise, which is attributable to heat loss due to the greater surface area to mass ratio and large number of arteriovenous anastomoses. Also, the smaller increase in T(re) in MY may be explained by the presence of a significantly greater core-skin temperature gradient in MY than JP. The thermal gradient is also a major factor in increasing the convective heat transfer from core to skin as well as skin blood flow. It is concluded that the greater core-skin temperature gradient observed in MY is responsible for the smaller increase in T(re).


Subject(s)
Body Temperature Regulation/physiology , Heat-Shock Response/physiology , Acclimatization/physiology , Asian People , Climate , Exercise/physiology , Hemodynamics , Hot Temperature/adverse effects , Humans , Humidity/adverse effects , Japan , Malaysia , Male , Skin/blood supply , Skin Temperature/physiology , Sweating/physiology , Tropical Climate/adverse effects , Young Adult
15.
Int J Biometeorol ; 55(4): 491-500, 2011 Jul.
Article in English | MEDLINE | ID: mdl-20824480

ABSTRACT

The objective of this study was to investigate thermoregulatory responses to heat in tropical (Malaysian) and temperate (Japanese) natives, during 60 min of passive heating. Ten Japanese (mean ages: 20.8 ± 0.9 years) and ten Malaysian males (mean ages: 22.3 ± 1.6 years) with matched morphological characteristics and physical fitness participated in this study. Passive heating was induced through leg immersion in hot water (42°C) for 60 min under conditions of 28°C air temperature and 50% RH. Local sweat rate on the forehead and thigh were significantly lower in Malaysians during leg immersion, but no significant differences in total sweat rate were observed between Malaysians (86.3 ± 11.8 g m(-2) h(-1)) and Japanese (83.2 ± 6.4 g m(-2) h(-1)) after leg immersion. In addition, Malaysians displayed a smaller rise in rectal temperature (0.3 ± 0.1°C) than Japanese (0.7 ± 0.1°C) during leg immersion, with a greater increase in hand skin temperature. Skin blood flow was significantly lower on the forehead and forearm in Malaysians during leg immersion. No significant different in mean skin temperature during leg immersion was observed between the two groups. These findings indicated that regional differences in body sweating distribution might exist between Malaysians and Japanese during heat exposure, with more uniform distribution of local sweat rate over the whole body among tropical Malaysians. Altogether, Malaysians appear to display enhanced efficiency of thermal sweating and thermoregulatory responses in dissipating heat loss during heat loading. Thermoregulatory differences between tropical and temperate natives in this study can be interpreted as a result of heat adaptations to physiological function.


Subject(s)
Acclimatization/physiology , Body Temperature Regulation/physiology , Immersion/adverse effects , Immersion/physiopathology , Asian People , Climate , Heat-Shock Response/physiology , Hot Temperature/adverse effects , Humans , Japan , Leg , Malaysia , Male , Sweating/physiology , Tropical Climate/adverse effects , Young Adult
16.
J Therm Biol ; 35(2): 70-76, 2010 Feb.
Article in English | MEDLINE | ID: mdl-28799915

ABSTRACT

The purpose of this study was to investigate ethnic differences in cutaneous thermal sensation thresholds and the inter-threshold sensory zone between tropical (Malaysians) and temperate natives (Japanese). The results showed that (1) Malaysian males perceived warmth on the forehead at a higher skin temperature (Tsk) than Japanese males (p<0.05), whereas cool sensations on the hand and foot were perceived at a lower Tsk in Malaysians (p<0.05); (2) Overall, the sensitivity to detect warmth was greater in Japanese than in Malaysian males; (3) The most thermally sensitive body region of Japanese was the forehead for both warming and cooling, while the regional thermal sensitivity of Malaysians had a smaller differential than that of Japanese; (4) The ethnic difference in the inter-threshold sensory zone was particularly noticeable on the forehead (1.9±1.2C for Japanese, 3.2±1.6°C for Malaysians, p<0.05). In conclusion, tropical natives had a tendency to perceive warmth at a higher Tsk and slower at an identical speed of warming, and had a wider range of the inter-threshold sensory zone than temperate natives.

17.
Eur J Appl Physiol ; 109(1): 73-80, 2010 May.
Article in English | MEDLINE | ID: mdl-19787368

ABSTRACT

The purpose of the present study was to examine the discrepancies in rectal temperature (T (re)) at various depths. Nineteen young males performed two bouts of bicycle exercise and recovery. T (re) was simultaneously measured at depth of 4, 6, 8, 10, 13, 16, and 19 cm, alongside the measurement of skin temperatures. We found small but statistically significant differences by depth in the absolute T (re), the magnitude of rise in T (re) and the lag of response in T (re). During the stabilization stage before exercise, T (re) at 4 cm-depth was 0.5 degrees C lower than T (re) at 16 cm-depth (p < 0.05). As the depth measured in the rectum was shallower, the rise in T (re) during exercise was greater. However the rise in T (re) at 10, 13, 16 and 19 cm showed no systemic difference. Among seven depths, T (re) at 16 cm-depth had the most stable feature with the longest latent period (3.1 +/- 1.3 min) and the smallest rise (0.8 +/- 0.3 degrees C), while T (re) at 4 cm-depth was the most responsive to the change of exercise and rest with the shortest latent period (1.0 +/- 0.6 min) and the greatest rise (1.2 +/- 0.5 degrees C). The differences observed in the depths from 4 to 19 cm were offset by exercise to some extent. In summary, T (re) appeared in different manners according to the seven depths during the repetition of exercise and rest, but T (re) deeper than 10 cm-depth seemed to have no systematic differences.


Subject(s)
Anal Canal/physiology , Body Temperature Regulation , Body Temperature/physiology , Exercise/physiology , Rest/physiology , Adult , Bicycling , Exercise Test , Humans , Male , Young Adult
18.
J Physiol Anthropol ; 28(6): 253-9, 2009 Nov.
Article in English | MEDLINE | ID: mdl-20009372

ABSTRACT

It is well known that women are physiologically and psychologically influenced by the menstrual cycle. In addition, the presence of background noise may affect task performance. So far, it has proven difficult to describe how the menstrual cycle and background noise affect task performance; some researchers have found an increment of performance during menstruation or during the presence of noise, others found performance deterioration, while other still have reported no dominant effect either of the menstrual cycle in performance or of the presence of noise. However, no study to date has investigated the combinational effect between the menstrual cycle and the presence of background noise in task performance. Therefore, the purpose of this study was to examine the combined factor effect of menstrual cycle and background noise on visual inspection task performance indices by Signal Detection Theory (SDT) metrics: sensitivity index (d') and response criteria index (beta). For this purpose, ten healthy female students (21.5+/-1.08 years) with a regular menstrual cycle participated in this study. A VDT-based visual inspection task was used for the experiment in 3x2 factorial designs. Two factors, menstrual phase, pre-menstruation (PMS), menstruation (M), and post-menstruation (PM) and background noise, with 80 dB(A) background noise and without noise, were analyzed as the main factors in this study. The results concluded that the sensitivity index (d') of SDT was affected in all the menstrual cycle conditions (p<0.01) and the presence of background noise (p<0.05) but no combinational effect of menstrual cycle and background noise was found in this study. On the other hand, no significant effect was observed in the subject's tendency in visual inspection, shown by beta along the menstrual cycle and the presence of background noise. According to the response criteria for each individual subject, the presence of noise affected the tendency of some subjects in detecting the object and making decision during the visual inspection task.


Subject(s)
Menstrual Cycle/physiology , Noise , Task Performance and Analysis , Visual Perception/physiology , Female , Humans , Surveys and Questionnaires , Young Adult
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