Restoration of isotropy on fractals

We report a new type of restoration of macroscopic isotropy (homogenization) in fractals with microscopic anisotropy. The phenomenon is observed in various physical setups, including diffusions, random walks, resistor networks, and Gaussian field theories. The mechanism is unique in that it is absent in spaces with translational invariance, while universal in that it is observed in a wide class of fractals.Comment: 11 pages, REVTEX, 3 postscript figures. (Compressed and encoded figures archived by "figure" command). To appear in Physical Review Letter

マウス運動神経末端における伝達物質遊離に対する塩化第一スズおよび塩化第二スズの作用

Stannous chloride (SnCl_2) is thought to facilitate the transmitter release from the motor nerve terminals. Stannous ions tend to become oxidized to stannic ions (Sn^) in the presence of water and oxygen. Therefore, the results seen with SnCl_2 until now might reflect the properties of Sn^. In the present study, to ascertain whether SnCl_2 facilitates the transmitter release from mouse motor nerve terminals, we compared the effects of stannic chloride (SnCl_4) on the miniature endplate potential (m. e. p. p.) frequency and the quantal content of the endplate potential (e. p. p.) with those of SnCl_2. We statistically analyzed the mean values of the differences of SnCl_2 (30μM) from its control and of SnCl_4 (30μM) from its control. There were significant differences between the two, both in the m. e. p. p. frequency and in the quantal content. The results obtained demonstrate that the actions of Sn^ are not involved in the effects shown by SnCl_2. We conclude that SnCl_2 facilitates the transmitter release from mouse motor nerve terminals

Vertical distribution of size fractionated phytoplankton chlorophyll in the Indian sector of the Southern Ocean in summer(1985/86)

During the icebreaker SHIRASE cruise of the 27th Japanese Antarctic Research Expedition (JARE-27; 1985/86), vertical profiles of phytoplankton chlorophyll a concentration in the upper 200m of the water column were observed at 12 stations in the Southern Ocean and at 3 stations in the subtropical water from December 1985 to March 1986. High phytoplankton chlorophyll standing crops (ca. 370mg m^ in December and 330mg m^ in February) were observed in Breid Bay, Antarctica. In other stations of the Antarctic Ocean, the standing crops were less than 52mg m^. Size fractionation studies revealed that net-phytoplankton (>20μm) was the dominant fraction of total chlorophyll a during the summer bloom in Breid Bay. In Antarctic waters, the high contributions of the net-phytoplankton fraction corresponded to high total biomass. And also, contribution of the net-phytoplankton to the total phytoplankton was supposed to be controlled by the length of the ice-free period. Considering the high phytoplankton growth rates under the nutrient rich condition, duration under optimum light condition and water stability appear to be important factors affecting the phytoplankton crops in the Antarctic Ocean in summer

Rectification of Digitized Aerial Photographic Image

A practical example of digital rectification of tilted photographs using a drum scanning micro densitometer and general purpose computers is depicted. The present research covers rectification of projective distorsions, occuring when the camera axis is not truly vertical, and affine distorsions due to curvature of a drum of a scanner. For this purpose, fundamental mathematical expressions were derived. And some pixel interpolation methods necessary for image reconstruction were compared experimentally. The examples revealed, however, that the film was deformed so complexly that they could not be corrected sufficiently only by affine transformation. Accuracy of rectification was checked by use of stereo aerial photographs in terms of residual y-parallaxes. The result showed residual y-parallaxes of ± 1 pixel (± 50 μm) and sometimes ± 2 pixels were observed. They seem to be caused mainly by film deformations which have not been eliminated, and their amount seems to exceed the photogrammetric tolerance

Photosynthetic physiology and primary productivity of phytoplankton in the Australian sector of the Southern Ocean

第2回極域科学シンポジウム　共通セッション「海氷圏の生物地球化学」 11月16日（水） 統計数理研究所 3階セミナー