Small-Amplitude Disturbances in a Radiating and Scattering Grey MediumIII. Gravitational Effects on the Solutions of Given Real Wave Number k     

Noboru Kaneko  Kazuhiko Morita 《Astrophysics and Space Science》2006,305(4):349-376

We study the fundamental modes of radiation hydrodynamic linear waves that arise from one-dimensional small-amplitude initial fluctuations with wave number k in a radiating and scattering grey medium by taking into account the gravitational effects. The equation of radiative acoustics is derived from three hydrodynamic equations, Poisson’s equation, and two moment equations of radiation, by assuming a spherical symmetry for the matter and radiation and by using the Eddington approximation. We solve the dispersion relation as a quintic function of angular frequency ω, the wave number k being a real parameter. Numerical results reveal that wave patterns of five solutions are distinguished into three types: the radiation-dominated, type 1, and type 2 matter-dominated cases. In the case of no gravitaional effects (Kaneko et al., 2005), the following wave modes appear: radiation wave, conservative radiation wave, entropy wave, Newtonian-cooling wave, opacity-damped and cooling-damped waves, constant-volume and constant-pressure diffusions, adiabatic sound wave, cooling-damped and drag-force-damped isothermal sound waves, isentropic radiation-acoustic wave, and gap mode. Meanwhile, the gravitaional effects being taken into account, the growing gravo-diffusion mode newly arises from the constant-pressure diffusion at the point that k agrees with Jeans’ wave number specified by the isothermal sound speed. This mode changes to the growing radiation-acoustic gravity mode near the point that k becomes Jeans’ wave number specified by the isentropic radiation-acoustic speed. In step with a transition between them, the isentropic radiation-acoustic wave splits into the damping radiation-acoustic gravity mode and constant-volume diffusion. The constant-volume diffusion emerges twice if the gravitational effects are taken into account. Since analytic solutions are derived for all wave modes, we discuss their physical significance. The critical conditions are given which distinguish between radiation-dominated and type 1 matter-dominated cases, and between type 1 and type 2 matter-dominated cases. Waves in a self-gravitating scattering grey medium are also analyzed, which provides us some hints for the effects of energy and momentum exchange between matter and radiation.  相似文献   

Contamination of organotin compounds and imposex in molluscs from Vancouver,Canada     

Horiguchi T  Li Z  Uno S  Shimizu M  Shiraishi H  Morita M  Thompson JA  Levings CD 《Marine environmental research》2004,57(1-2):75-88

Gastropods and bivalves were collected at 15 sites at Vancouver and Victoria, Canada between 24 May and 7 June, 1999, to establish tissue concentrations of butyltin and phenyltin compounds, to record imposex symptoms in gastropods, and to assess the present status of organotin contamination around Vancouver. No neogastropods (such as Nucella lima) were found around Vancouver. Neogastropod populations could have been extirpated by severe TBT contamination in Vancouver, as relatively high concentrations of TBT were detected in tissues of Mytilus trossulus from Vancouver, and the neogastropods distributed in Vancouver might be sensitive to TBT. Recovery from imposex, however, was observed in neogastropod populations from three sites at Victoria and Mission Point. TBT contamination has continued around Vancouver, arising from continuous use of TBT in antifouling paints for vessels larger than 25 m in length; however, TBT has decreased around Victoria and Mission Point. Different patterns of TBT accumulation in tissue were observed among the bivalve species from Vancouver. The highest TBT concentration detected in Tresus capax suggested some possible adverse effects. TBT was the most predominant butyltin component in almost all bivalve specimens surveyed, suggesting a low rate of TBT metabolism. Phenyltin compounds were not detected in any molluscan specimens in this study.  相似文献   

Light scattering and size distribution of particles in the surface waters of the North Pacific Ocean   总被引：1，自引：0，他引：1  

Shigehiko Sugihara  Ryohei Tsuda 《Journal of Oceanography》1979,35(2):82-90

The volume scattering function and size distribution of suspended particles in the surface water were determined in the North Pacific. The relationship between the scattering coefficient estimated from observed volume scattering function and cross-section concentration of the particles greater than 2.4m in diameter was found to be linear in both northern and southern regions of central North Pacific. Difference in the constant of proportionality between two regions, however, was very great. Moreover the constant in the southern region was too large compared with the values obtained by the Mie theory. This is considered to be due to the fact that particles smaller than 2.4m which were not measureable by the Coulter Counter, were neglected in the calculation of cross-section concentration. If small particles are taken into consideration, total cross-section concentration and scattering coefficient in the two regions tend to follow a linear relation. From the correlation between the scattering coefficient computed from size distribution and the volume scattering function, the refractive index of particles was estimated to be 1.03–1.05. By the same procedure, the refractive index of particles in Tateyama Harbour where the water was very turbid, was estimated to be also 1.03–1.05. This is in contrast to the result for the refractive index of particles originating from the river which flows into the harbour. This index was found to be 1.10–1.20.  相似文献   

Correlation of chlorophyll concentrations and suspended solids with near-surface upward irradiance within LANDSAT bands 4, 5 and 6     

Shigehiko Sugihara  Motoaki Kishino  Noboru Okami 《Journal of Oceanography》1985,41(2):81-88

Near-surface upward irradiances within each band of the MSS (multi spectral scanner) of LANDSAT, were computed from observed spectral upward irradiances measured just beneath the sea surface. Computation of these irradiances is a useful first step in the analysis of remotely-sensed radiance because the data are not affected by the effects of the atmosphere and sea surface. The computed irradianceE in LANDSAT bands 4, 5 and 6 was normalized by forming ratios,i.e., R ₄₅=E₄/E₅, R₄₆=E₄/E₆, andR ₅₆=E₅/E₆, and then the relationship between these ratios and chlorophylla plus phaeopigment concentration (C) observed simultaneously at 59 stations was examined by linear regression analysis. The observedC ranged over nearly three orders of magnitude, and there is a close to linear relationship between log₁₀-R ₄₅ and log₁₀ C. This suggests that it may be possible to evaluateC from LANDSAT data, if an appropriate atmospheric correction is made. The relationship between suspended solids determined at 35 stations and the same ratios of upward irradiance is also presented and discussed.  相似文献   

Growth of chum salmon (Oncorhynchus keta) correlated with sea-surface salinity in the North Pacific   总被引：1，自引：0，他引：1  

Morita  Shoko H.; Morita  Kentaro; Sakano  Hiroyuki 《ICES Journal of Marine Science》2001,58(6):1335-1339

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Relative microbial activity and mineralization associated with water masses in the lower Cook Inlet,Alaska     

R. P. Griffiths  T. M. McNamara  S. E. Steven  R. Y. Morita 《Journal of Oceanography》1981,37(5):227-233

A study of the microbial uptake and respiration (mineralization) of radioactive glutamic acid was made in 141 surface water samples in the Cook Inlet, Alaska during three sampling periods (October, 1976; April, 1977; and November, 1977). The rate at which the test substrate was incorporated into cell material plus that respired as CO₂ was used to calculate the relative microbial activity. A northern water mass with salinities less than 31 showed high rates of relative microbial activity but low mineralization rates as indicated by respiration of¹⁴CO₂. The reverse pattern was seen in the water mass (salinity higher than 31) to the south which was more typical of coastal water. These data suggest that the organic nutrients in these two water masses are quite different either qualitatively or quantitatively. This study illustrates how the observed measurement of relative microbial activity might be helpful in defining specific water masses.(The publication of this article was unintentionally delayed owing to a fault in secretarial routine.)Published as Technical Paper No. 6009, Oregon Agricultural Experiment Station.  相似文献   

Long-term effects of crude oil on microbial processes in subarctic marine sediments: Studies on sediments amended with organic nutrients     

Robert P. Griffiths  Bruce A. Caldwell  William A. Broich  Richard Y. Morita 《Marine pollution bulletin》1982,13(8):273-278

Subarctic marine sediments amended with various organic compounds were exposed to fresh Cook Inlet crude oil at a concentration of 50 ppt for either 6 or 8 months. After the sediments were initially treated, they were returned to the approximate location where they were collected and left to be exposed to natural environmental conditions until they were retrieved for analysis. As a result of crude oil treatment, the activities of the enzymes that hydrolyse structural polysaccharides were reduced and the activities of the enzymes that hydrolyse storage polysaccharides were stimulated. In addition to these changes, we observed changes in phosphatase activity, nitrogen fixation rates, potential denitrification rates, methane concentrations, CO₂ production rates, and the glucose uptake and mineralization rates. The effect of the crude oil perturbation was different depending on the organic compound used in the amended sediments. Many of these differences could be explained by the effect of crude oil on the hydrolases which were responsible for degrading the compound in question. The results of this study suggest the effect of crude oil on microbial processes may be affected by the type of organic material present in the impacted marine sediment. This study also illustrates the value of measuring hydrolase activity in studies designed to determine the effects of this or any other pollutant on microbial processes in marine sediments.  相似文献   

ACTIVE system for monitoring volcanic activity: A case study of the Izu-Oshima Volcano,Central Japan     

Hisashi Utada  Yuji Takahashi  Yuichi Morita  Takao Koyama  Tsuneomi Kagiyama 《Journal of Volcanology and Geothermal Research》2007

A system is proposed for the monitoring of changes in the underground structure of an active volcano over time by applying a transient electromagnetic method. The monitoring system is named ACTIVE, which stands for Array of Controlled Transient-electromagnetics for Imaging Volcano Edifice. The system consists of a transmitter dipole used to generate a controlled transient electromagnetic (EM) field and an array of receivers used to measure the vertical component of the transient magnetic field at various distances, with automatic operation of both units. In order to verify the performance of the proposed system, numerical and field experiments were carried out by application of the system to the Izu-Oshima volcano, where a remarkable change in the apparent DC resistivity over time had been detected in association with the eruption in 1986.  相似文献   

Gonadal histology and serum vitellogenin levels of bigeye tuna Thunnus obesus from the Northern Pacific Ocean--absence of endocrine disruption bio-indicators     

Hashimoto S  Kurihara R  Strüssmann CA  Yamasaki T  Soyano K  Hara A  Shiraishi H  Morita M 《Marine pollution bulletin》2003,46(4):459-465

Endocrine disrupting chemicals such as organochlorines have been detected in a large number of marine fish. Histological observation of the gonads, measurement of serum vitellogenin (VTG) level and of liver polychlorinated biphenyl (PCB) content were performed to evaluate the reproductive health and the contamination with endocrine disruptors in bigeye tuna Thunnus obesus, collected in the northern Pacific Ocean in 1999 and 2000. Abnormalities commonly found in species affected by endocrine disruptors such as the presence of oocytes in the testis or elevated serum VTG levels were not found in any of males examined. Both males and females had only small amounts of liver PCB content. The results suggest that currently there is little if any risk of organochlorine contamination or endocrine disruption of gonadal function in bigeye tuna from the northern Pacific Ocean. However, further studies are necessary to evaluate the health status of the open sea fishery resources.  相似文献   

Erratum to “Analysis of rainfall characteristics of the Madden–Julian oscillation using TRMM satellite data” [Dyn. Atmospheres Oceans 42 (2006) 107–126]     

Juntaro Morita  Yukari N. Takayabu  Shoichi Sigue  Yasumasa Kodama 《Dynamics of Atmospheres and Oceans》2007,43(3-4):226-228

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