Despite an increase in the number of reports on professional oral care, there is no consensus view on the frequency of intervention. With regard to providing professional oral care to the dependent elderly, a frequency of 4 times per month may be most effective considering the limited time, cost, and manpower.

In order to observe atmospheric ions in the free troposphere, measurements of atmospheric positive ions in the critical mobility range 5.0 and 0.63 cm 2 /Vs were conducted at the summit of Mt. Fuji (35.36N, 138.73E, 3776 m a.s.l.) from Aug. 8 to 23, 2011. Positive atmospheric ions were found to have a clear diurnal variation, with minimum concentrations during nighttime and with maximum daytime, which is possibly linked to ions transportation by valley breeze. This variation is clearer when the observation station is out of clouds in planetary boundary layer. A strong anti-correlation was found between air ion concentrations and coagulation sink. Enhanced ion concentrations were found when air mass had been transported over the sea and coagulation sink value is low.

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