Distribution of larvae ofPinnixa rathbuni Sakai (Decapoda: pinnotheridae) in Ise Bay and its neighbouring coastal waters,central Japan part 3. Aggregation of the benthic adult population with reference to the spatial distribution of the planktonic larvae

According to studies made to date, the planktonic larvae ofPinnixa rathbuni, especially the early zoeal stages, have been found mainly in the eastern part of Ise Bay (Pacific coast of central Japan), while the benthic adult population is restricted to the southwestern part of the bay. The present study was made to obtain a better understanding of the origin of the dense population of early zoea found along the coast of the Chita Peninsula in the eastern part of the bay. Field surveys made with a Smith-McIntyre grab from May to November 1981 (every two months) ruled out the possibility that the benthic adult crabs in the southwestern part of the bay migrated to the eastern part of the bay to release their larvae, or that a substantial population of the crabs occurred in the eastern part of the bay. Thus, the larvae may be derived wholly from the benthic adult populations localized in the southwestern part of the bay. The spatial distribution of the early larvae can be explained by assuming that the larvae, released by the benthic adult population in the southwestern part of the bay, are rapidly transported toward the Chita Peninsula and form a dense larval population along the coast in the eastern part of the bay.     

High-Speed Data Acquisition System Messia for Subaru

We have developed a high-speed data acquisition system, Messia-III (Modularized Extensible SyStem for Image Acquisition) for Subaru, Japanese 8.2m telescope. Messia has a direct 1-Gbps link to a host UNIX workstation. Messia is a VMEbus-based system but it does not have local OS nor CPU's in order to minimize software development and maintenance.     

A camera using a 1040×1040 array

A JHKK survey camera based on a 1040×1040 PtSi Charge Sweep Device has been constructed in a joint programme of the University of Tokyo, the National Astronomical Observatory of Japan and the South African Astronomical Observatory. We describe its design, construction and initial testing.     

Development of a Neural Network Algorithm for Retrieving Concentrations of Chlorophyll, Suspended Matter and Yellow Substance from Radiance Data of the Ocean Color and Temperature Scanner

An algorithm is presented to retrieve the concentrations of chlorophyll a, suspended pariclulate matter and yellow substance from normalized water-leaving radiances of the Ocean Color and Temperature Sensor (OCTS) of the Advanced Earth Observing Satellite (ADEOS). It is based on a neural network (NN) algorithm, which is used for the rapid inversion of a radiative transfer procedure with the goal of retrieving not only the concentrations of chlorophyll a but also the two other components that determine the water-leaving radiance spectrum. The NN algorithm was tested using the NASA's SeaBAM (SeaWiFS Bio-Optical Mini-Workshop) test data set and applied to ADEOS/OCTS data of the Northwest Pacific in the region off Sanriku, Japan. The root-mean-square error between chlorophyll a concentrations derived from the SeaBAM reflectance data and the chlorophyll a measurements is 0.62. The retrieved chlorophyll a concentrations of the OCTS data were compared with the corresponding distribution obtained by the standard OCTS algorithm. The concentrations and distribution patterns from both algorithms match for open ocean areas. Since there are no standard OCTS products available for yellow substance and suspended matter and no in situ measurements available for validation, the result of the retrieval by the NN for these two variables could only be assessed by a general knowledge of their concentrations and distribution patterns. This revised version was published online in July 2006 with corrections to the Cover Date.     

A photometric study of poor clusters of galaxies

Sixteen poor clusters of galaxies with suspected cD galaxies are studied usingV-band photographs taken with the 105 cm Kiso Schmidt telescope. Galaxian images were automatically detected using an image detection software developed for the present study. It is found from the luminosity functions that the richness of the clusters are well correlated with the optical properties of central galaxies and the X-ray luminosities of the clusters.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.     

Field Survey of Tsunami Effects in Sri Lanka due to the Sumatra-Andaman Earthquake of December 26, 2004

The December 26, 2004 Sumatra-Andaman earthquake that registered a moment magnitude (M_w) of 9.1 was one of the largest earthquakes in the world since 1900. The devastating tsunami that resulted from this earthquake caused more casualties than any previously reported tsunami. The number of fatalities and missing persons in the most seriously affected countries were Indonesia - 167,736, Sri Lanka - 35,322, India - 18,045 and Thailand - 8,212. This paper describes two field visits to assess tsunami effects in Sri Lanka by a combined team of Japanese and Sri Lankan researchers. The first field visit from December 30, 2004 – January 04, 2005 covered the western and southern coasts of Sri Lanka including the cities of Moratuwa, Beruwala, Bentota, Pereliya, Hikkaduwa, Galle, Talpe, Matara, Tangalla and Hambantota. The objectives of the first field visit were to investigate the damage caused by the tsunami and to obtain eyewitness information about wave arrival times. The second field visit from March 10–18, 2005 covered the eastern and southern coasts of Sri Lanka and included Trincomalee, Batticaloa, Arugam Bay, Yala National Park and Kirinda. The objectives of the second visit were mainly to obtain eyewitness information about wave arrival times and inundation data, and to take relevant measurements using GPS instruments.     

On the theoretical possibility of the libration cloud

In the present paper, the problem of whether the interplanetary matter has a tendency to accumulate around the Lagrangian libration pointsL ₄ andL ₅, is examined statistically. It is concluded that: (1) If the particles are initially assumed to be distributed uniformly, they keep the uniformity ever after around the libration points. (2) If the particles receive random stochastic perturbations, their distribution tends to become uniform even if initially they have non-uniform distributions. (3) If the particles mutually collide inelastically, they have a tendency to avoid the regions near the libration points. Therefore, the interplanetary matter will not tend to accumulate near the libration points. Even if the observations of the libration cloud so far reported are confirmed, the clouds are likely to be but temporary objects.