Winter breeding of black swan Cygnus atratus in a solar greenhouse with a water pond.

Winter propagation of black swans Cygnus atratus is introduced at Kwangpho on the east coast of the Democratic People's Republic of Korea located in the temperate zone of northeast Asia. The natural lake Kwangpho was selected as a rearing site to provide the environment which matched most closely to black swan's natural habitats. Comparison of the climate data of Kwangpho with Australia and New Zealand led to the conclusion that it is necessary to increase winter temperature 10 °C for artificial rearing. In order to overcome the low temperature with renewable energy, a passive solar greenhouse with a water pond was introduced, where black swans were reared simultaneously while observing the microclimate such as air temperature, humidity and water temperature in winter. When the pond depth was 0.4 m and 0.8 m, there was no significant difference in indoor temperature, the depth fixed at 0.4 m to reduce pumping power by more than 50%. During the study, 80 mature black swans wintered safely and 13 pairs of them laid 74 eggs, the artificial hatching rate was 65% and the natural hatching rate was 53%. It was confirmed that the passive solar greenhouse with a pond can raise the winter minimum temperature 8-10 °C higher than outside, and in this microclimate it is possible to propagate the black swan and it is believed that the greenhouse has abundant potential to enable the artificial breeding as well as wintering of black swans, in temperate zone occupying wide area of the earth.

Awareness of and compliance with healthy oral habits reported by children and their parents in Democratic People's Republic of Korea after a preventive programme.

OBJECTIVE: The study aimed to examine awareness of and compliance with healthy oral habits reported by children and their parents in Pyongyang, Democratic People's Republic of Korea (DPRK), after a preventive programme. MATERIALS AND METHODS: The data were collected in 2013 with self-completed, partly structured questionnaires from 1994 children aged 10 and 13 years and from 200 parents. Association between awareness of and compliance with healthy oral habits reported by the children and their parents was evaluated using Chi square tests and multivariate logistic regression analyses, children's oral health habits according to themselves and their parents were analysed using McNemar's test. RESULTS: Both children and their parents seemed to be familiar with healthy oral habits, although the awareness was not directly related to the reports of the children's oral practices. Most of the children reported brushing their teeth at least twice a day, using fluoride toothpaste and drinking water for thirst but frequent sweet snacking was common. Children's and their parents' reports were consistent with regard to sweet snacking frequency (p = 0.736) and the main thirst quencher (p = 0.349). CONCLUSIONS: Awareness of healthy oral habits appeared to be good among children and their parents. Unhealthy oral habits seemed to coincide with one another.