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41.
Somchai Isichaikul Koichi Fujimura Toshihide Ichikawa 《Researches on Population Ecology》1994,36(1):23-28
Nymphs ofNilaparvata lugens were experimentally reared from the 2nd instar in a cage covering part of the leaf sheath of an individual rice plant grown
in a Wagner pot. Plants were covered with the cage from the water surface of the pot to 10 cm above the surface (lower cage-group)
or from 10 cm to 20 cm above the surface (upper cage-group). Temperatures measured at three different parts of the cage remained
fairly constant in both groups at around 25°C (23.7–25.2°C in mean value). In the lower cage-group, relative humidities measured
at the three heights in the cage in (76.3–90.5% in mean value) markedly increased with the approach to the water surface.
The nymphs of this group, particularly during the molting period, aggregated close to the surface. Eighty-two percent of the
released nymphs emerged in this group. Relative humidities measured at three heights of the upper cage-group were 69.5–72.7%
in mean value, and all the nymphs in this group died within 3 days after their release although half of them stayed on the
rice plants within 6 h after their release. The role of relative humidity as a limiting factor on the range of the microhabitat
and the population density ofN. lugens in rice fields was discussed on the basis of the results. 相似文献
42.
We consider the problem of fair allocation in economies with indivisible goods. Our primary concept is that of an envy-free allocation, that is, an allocation such that no agent would prefer anyone else's bundle to his own. Since there typically is a large set (a continuum) of such allocations, the need arises to identify well-behaved selections from the no-envy solution. First we establish the non-existence of population monotonic selections. Then we propose a variety of selections motivated by intuitive considerations of fairness. 相似文献