De Novo Formation of Left–Right Asymmetry by Posterior Tilt of Nodal Cilia

In the developing mouse embryo, leftward fluid flow on the ventral side of the node determines left–right (L-R) asymmetry. However, the mechanism by which the rotational movement of node cilia can generate a unidirectional flow remains hypothetical. Here we have addressed this question by motion and morphological analyses of the node cilia and by fluid dynamic model experiments. We found that the cilia stand, not perpendicular to the node surface, but tilted posteriorly. We further confirmed that such posterior tilt can produce leftward flow in model experiments. These results strongly suggest that L-R asymmetry is not the descendant of pre-existing L-R asymmetry within each cell but is generated de novo by combining three sources of spatial information: antero-posterior and dorso-ventral axes, and the chirality of ciliary movement

The effects of indoor temperature and outdoor air supply rate on learning performance of late-teen students

ABSTRACT In order to investigate the impact of IEQ on learning performance, intervention field experiments were carried out at two technical colleges in Japan. Indoor temperature and outdoor air supply rate were changed at 3 levels (22, 25, 28°C; 5, 10, 20 m 3 /h/person), and 5 combinations of them were adopted as the experimental cases. The learning performance was evaluated with a 30-min examination after a 180-min video lecture. The examination score was found to be improved when PMV was close to zero, or outdoor air supply rate was increased. According to the comparisons with previous studies, it was considered that the learning performance of young people is more affected by the indoor temperature and outdoor air supply rate than that of older people

Study on association between indoor thermal environment of residential buildings and cerebrovascular disease in a cold climatic region of Japan

Purpose / Context - The aim of this study was to determine whether the quality of the indoor ther-mal environment during winter could increase the risk of cerebrovascular disease. Methodology / Approach - An epidemiological survey of approximately 200 elderly persons living in a cold climatic region of Japan was conducted. The survey was divided into three phases, and the investigated areas were three rural towns with different rates of death due to cerebrovascular disease. Results – Results indicate that feeling a draft in the living room while operating heating equipment and the style of bathtub were positively associated with an increased rate of death due to cerebro-vascular disease. The bathroom with a traditional type bathtub tends to be cold, and its indoor thermal environment during winter is poor. Key Findings / Implications – Poor quality of the indoor environment during winter could increase the risk of cerebrovascular disease. Originality – The fidings of this study will contribute to accumulate the knowledges showing the associations between indoor thermal environment and health

Thermal sensation and thermophysiological responses with metabolic step-changes

This study investigated the effect on thermal perception and thermophysiological variables of controlled metabolic excursions of various intensities and durations. Twenty-four subjects were alternately seated on a chair or exercised by walking on a treadmill at a temperature predicted to be neutral at sedentary activity. In a second experimental series, subjects alternated between rest and exercise as well as between exercise at different intensities at two temperature levels. Measurements comprised skin and oesophageal temperatures, heart rate and subjective responses. Thermal sensation started to rise or decline immediately (within 1 min) after a change of activity, which means that even moderate activity changes of short duration affect thermal perceptions of humans. After approximately 15–20 min under constant activity, subjective thermal responses approximated the steady-state response. The sensitivity of thermal sensation to changes in core temperature was higher for activity down-steps than for up-steps. A model was proposed that estimates transient thermal sensation after metabolic step-changes. Based on predictions by the model, weighting factors were suggested to estimate a representative average metabolic rate with varying activity levels, e.g. for the prediction of thermal sensation by steady-state comfort models. The activity during the most recent 5 min should be weighted 65%, during the prior 10–5 min 25% and during the prior 20–10 min 10%.10 page(s

Thermal sensation and comfort with transient metabolic rates

This study investigated the effect on thermal perceptions and preferences of controlled metabolic excursions of various intensities (20%, 40%, 60% relative work load) and durations (3-30 min) imposed on subjects that alternated between sedentary activity and exercise on a treadmill. The thermal environment was held constant at a temperature corresponding to PMV=0 at sedentary activity. Even low activity changes of short duration (1 min at 20% relative work load) affected thermal perceptions. However, after circa 15 min of constant activity, subjective thermal responses approximated the steady-state response, after both up-steps and down-steps of activity.6 page(s