Real-time difference imaging analysis of MOA Galactic bulge observations during 2000     

I.A. Bond  F. Abe  R.J. Dodd  J.B. Hearnshaw  M. Honda  J. Jugaku  P.M. Kilmartin  A. Marles  K. Masuda  Y. Matsubara  Y. Muraki  T. Nakamura  G. Nankivell  S. Noda  C. Noguchi  K. Ohnishi  N.J. Rattenbury  M. Reid  To. Saito  H. Sato  M. Sekiguchi  J. Skuljan  D.J. Sullivan  T. Sumi  M. Takeuti  Y. Watase  S. Wilkinson  R. Yamada  T. Yanagisawa  P.C.M. Yock 《Monthly notices of the Royal Astronomical Society》2001,327(3):868-880

We describe observations carried out by the MOA group of the Galactic bulge during 2000 that were designed to detect efficiently gravitational microlensing of faint stars in which the magnification is high and/or of short duration. These events are particularly useful for studies of extrasolar planets and faint stars. Approximately 17 deg² were monitored at a sampling rate of up to six times per night. The images were analysed in real time using a difference imaging technique. 20 microlensing candidates were detected, of which eight were alerted to the microlensing community whilst in progress. Approximately half of the candidates had high magnifications (≳10), at least one had very high magnification (≳50), and one exhibited a clear parallax effect. The details of these events are reported here, together with details of the on-line difference imaging technique. Some nova-like events were also observed and these are described, together with one asteroid.  相似文献   

On the parasitic organisms in a krill,Euphausia similis,from Suruga Bay     

Yuzo Komaki 《Journal of Oceanography》1970,26(5):283-295

A considerable number ofEuphausia similis G. O. Sars were found to be infected with a parasite in the samples collected in the summer of 1969 in Suruga Bay. The same species was also parasitized by an ellobiopsid,Thalassomyces fagei (Boschma), but it was rare in occurrence. The former parasite is slightly oval in shape with the longer diameter ranging between 1.0 and 1.5 mm, average diameter 1.35 mm. It infests cardiac region, rarely gastric region, of the host. It has been preliminarily identified by Drs.T. Oshima andT. Shimazu of the Shinshu University as the progenetic metacercaria of a trematode species very closely related toPseudopecoelus japonicus; its adult was originally reported to infest several bathypelagic fishes and the encysted stage was also found in jack mackerel from Suruga Bay byYamaguti (1938). The occurrence of the metacercaria inE. similis from the area may be new to science, althoughG. O. Sars (1885) has reported the immature forms ofDistomum filiferum G. O. Sars inNematoscelis megalops G. O. Sars andThysanoessa gregaria G. O. Sars and the crustaceans of wide variety have been proved to serve as the second intermediate host of various trematodes. The euphausiids infected with the metacercaria were concentrated in the innermost part of the bay. This might suggest the presence of the euphausiid population which is confined to the geographical area for some period. The metacercaria may be used as a “biological tag” to trace the migratory range of the host when the life history of the parasite is elucidated. The finding ofT. fagei in the area may be the first record of occurrence of the species in the western North Pacific, andE. similis is now recorded as the fourteenth known host euphausiid of the ellobiopsid.  相似文献   

Zinc-rich Pyrite from the TAG Active Mound, the TAG Hydrotherma Field, Mid-Atlantic Ridge     

Su Young Lee    Masatsugu Ohnishi    Yasuhiro Shibata    Makoto Wwatanabe    Kenichi Hoshino    Mayumi Jige    Xiangping Gu  Hitoshi Chiba  Tamotsu Oomori    Kantaro Fujioka  Peter A. Rona 《Resource Geology》2001,51(1):63-68

Abstract: Pyrite rich in Zn, up to 3.1 wt%, was found in the TAG active mound of the TAG hydrothermal field, the slow-spreading Mid-Atlantic Ridge at 26°08'N and 44°49'W. The Zn-rich pyrite is characterized by an optical homogeneity, a homogeneous distribution of Zn in the back-scattered electron images, both at a magnification of about 500, a negative correlation between Fe and Zn contents of the pyrite and a rather small unit cell edge (a₀ = 5.4117 ± 0.0008Å), strongly indicating that the detected Zn is present in the pyrite in solid solution. Such Zn concentrations are observed exclusively in dendritic pyrite, suggesting that the Znrich pyrite grew from hydrothermal fluids of a high degree of supersaturation due to quenching on the seafloor.  相似文献   

Temperature dependent nuclear mass and its application to astrophysical problems     

Teruaki Ohnishi 《Astrophysics and Space Science》1973,20(1):225-239

Temperature dependent nuclear binding energies are proposed. The binding energies for some 170 nuclides in 40A66 are computed at several temperatures according to this model. The abundances of the nuclides in the above atomic mass region are then calculated for example by using these temperature dependent binding energies. It becomes clear that this type of binding energies makes the abundances of near closed-shell nuclides increased and/or the abundances of off-shell nuclides decreased. These binding energies can lead the more consistent theoretical abundances at least of the silicon-burning products than any ones calculated up to the present.  相似文献   

1975年海城7.3级地震在朝鲜半岛的震害及对日本九州地区的影响s          下载免费PDF全文

李裕澈  秋教昇  石川有三 《地震学报》2007,29(2):214-221

1975年中国海城7.3级地震波及整个朝鲜半岛，乃至日本九州地区. 本文系统收集了该震有关资料，并通过整理分析勾画出其烈度分布，以探讨该震的震害特点. 在半岛的北部， 除局部地区为Ⅵ度之外，大部分地区为Ⅴ度区，其震害情况与相同烈度的典型特征基本相符； 半岛南部大部分地区为Ⅳ度区. 然而，韩国首尔等大城市，除高层建筑强烈振动之外，还有人出现眩晕症状等特别的感觉，个别街区变压器跳闸造成一时停电. 这些可能是大震的长周期波在远场的效应所致.   相似文献   

Some Investigations on Early Organization of Karst System     

Yu Qingchun 《中国地质大学学报(英文版)》1999,10(4):314-321

Karstsystemsaredynamicsystemsinspontaneoussuc-cessiveevolutionarisenfromtheinteractionbetweenwaterflowandsolub1emedium-Thecircu1ationofwaterprogres-sivelyandcontinuouslymodifiesthestructureofmediumfield,consequentlymodifyingthehydraulicbehaviorofthesystemitself'Someauthors(e.g.,FordandWilliams,l989)believedthatmostcarbonaterockswillbecomeconduitaquifersifsurficialerosionisnegligibleorsufficienttimeisgiven.Karstsystemsfailtodevelopconnectedconduiteitherduetoincompleteextension(becauseinsuffici…  相似文献   

Elastoplastic deformation around underground openings under biaxial initial stress field     

Yuzo Obara  Katsuhiko Sugawara 《国际地质力学数值与分析法杂志》1997,21(10):721-737

Estimation of elastoplastic deformation around an underground opening induced by the excavation of it, especially displacement and strain field in plastic region, is presented in this paper, as well as the formulation for calculating the displacement and strain in the plastic region around the underground opening by the coupled Boundary Element Method - Characteristics Method (BEM-CM). In this method, the non-associated flow rule is adopted to calculate the displacement and strain field in the plastic region, which is determined by the integration of the displacement along characteristics lines under the boundary condition of the elastic displacement on an elastoplastic interface analysed. It is shown that this method is one of the accurate and effective methods for estimating not only the shape and extent of the plastic region but also the state of the displacement and strain in the plastic region around the underground opening, comparing the theoretical solution with numerical results by this method for a circular opening under hydrostatic initial stress condition. Furthermore, this method is applied to rectangular and horse-shoe shaped openings and the characteristics of the strain field in the plastic region are discussed. © 1997 by John Wiley & Sons, Ltd.  相似文献   

Distribution of local Cs anomalies on the seafloor near the Fukushima Dai-ichi Nuclear Power Plant     

Blair Thornton  Seiki Ohnishi  Tamaki Ura  Naoteru Odano  Shun Sasaki  Tsuneo Fujita  Tomowo Watanabe  Kaoru Nakata  Tsuneo Ono  Daisuke Ambe 《Marine pollution bulletin》2013

An estimated 3.5 ± 0.7 × 10¹⁵ Bq of ¹³⁷Cs is thought to have been discharged into the ocean following the melt down at Fukushima Dai-ichi Nuclear Power Plant (F1NPP). While efforts have been made to monitor seafloor radiation levels, the sampling techniques used cannot capture the continuous distribution of radionuclides. In this work, we apply in situ measurement techniques using a towed gamma ray spectrometer to map the continuous distribution of ¹³⁷Cs on the seafloor within 20 km of the F1NPP. The results reveal the existence of local ¹³⁷Cs anomalies, with levels of ¹³⁷Cs an order of magnitude higher than the surrounding seafloors. The sizes of the anomalies mapped in this work range from a few meters to a few hundreds of meters in length, and it is demonstrated that the distribution of these anomalies is strongly influenced by meter scale features of the terrain.  相似文献   

Basin and crustal velocity structure models for the simulation of strong ground motions in the Kinki area,Japan     

Tomotaka Iwata  Takao Kagawa  Anatoly Petukhin  Yoshihiro Ohnishi 《Journal of Seismology》2008,12(2):223-234

We constructed a prototype of the basin and crustal structure model for the Kinki area, southwest of Japan, for the simulation of strong ground motions of hypothetical crustal and subduction earthquakes. We collected results of the deep seismic velocity profiles obtained by the reflection experiments and seismic imaging results, which were conducted in the Kinki area. The obtained profiles give underground velocity structures of the crust, from the surface to the subducting slab. We also gather the basin velocity structure information of the Osaka, Kyoto, Nara, and Ohmi basins. To examine the applicability of the constructed velocity structure model to the ground motion simulation, we simulated waveforms of an intermediate size event occurred near the source area of the hypothetical subduction earthquakes. Simulated ground motions using the basin and crustal velocity structure model are fairly well reproducing the observations at most of stations, and the constructed basin and crustal velocity structure model is applicable for the long-period ground motion simulations.  相似文献   

Energy determination of gamma-ray induced air showers observed by an extensive air shower array     

K. Kawata  T. K. Sako  M. Ohnishi  M. Takita  Y. Nakamura  K. Munakata 《Experimental Astronomy》2017,43(1):1-17

ASTRI SST-2M is one of the prototypes of the small size class of telescopes proposed for the Cherenkov Telescope Array. Its optical design is based on a dual-mirror Schwarzschild-Couder configuration, and the camera is composed by a matrix of monolithic multipixel silicon photomultipliers managed by ad-hoc tailored front-end electronics. This paper describes the procedures for the gain calibration on the ASTRI SST-2M. Since the SiPM gain depends on the operative voltage and the temperature, we adjust the operative voltages for all sensors to have equal gains at a reference temperature. We then correct gain variations caused by temperature changes by adjusting the operating voltage of each sensor. For that purpose the SiPM gain dependence on operating voltage and on temperature have been measured. In addition, we present the calibration procedures and the results of the experimental measurements to evaluate, for each pixel, the parameters necessary to make the trigger uniform over the whole focal plane.  相似文献