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51.
A logN — logS relation at 10 GHz is constructed for sources with the flat spectra 0.5 (flux densitySv
–) from observations at NRO, MPIfR and others. Based on the source distribution on log (Luminosity) volume plane we obtain an epoch-depending luminosity function which explains the above relation.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984.Nobeyama Radio Observatory, a branch of the Tokyo Astronomical Observatory, University of Tokyo, is a facility open for general use by researchers in the field of astronomy and astrophysics. 相似文献
52.
One-armedglobal oscillations in a non-selfgravitating polytropic disk rotating around a star are investigated. The unperturbed disk is axisymmetric, geometrically thin, and extends infinitely in the radial direction keeping its thickness constant. Perturbations considered are inviscid and adiabatic. It is found that there are one-armed retrograde wave modes which are trapped in an inner region of the disk. The eignefrequency of the lowest order mode is given by K(r
s)(z
0/r
s)2, wherer
s is the radius of the central star,z
0 is the half-thickness of the disk, and K(r
s) is the Keplerian angular frequency at the surface of the star.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
53.
Francesco Canganella Giovanna Bianconi Agata Gambacorta Chiaki Kato Katsuyuki Uematsu 《Marine Ecology》2002,23(S1):1-10
Abstract. Hydrothermal vent ecosystems have been extensively investigated during the last 20 years; shallow water hot springs (typically found below 50 m depth) have also been studied, and from these ecosystems many thermophilic and hyperthermophilic organisms were isolated and described.
The submarine caves of Cape Palinuro were discovered long ago, but only during the last decades were geological and biological investigations carried out, yielding a large number of reports on this fascinating environment. During the last two years, several samples of water, mud, and/or bacterial mat were collected within the "Grotta Azzurra", and enrichment experiments were performed using peptone, starch, glucose or pullulan as main organic nutrients. Many heterotrophic strains were isolated and most of them grew optimally between 37 and 43 ° C with the addition of 0-2 % NaCl. Growth was usually observed between 10 and 50 ° C the range of growth pH was 4 to 9, and NaCl concentrations up to 10–12 % were tolerated in most cases.
The analysis of 16S rDNA performed with the most representative isolates showed a close phylogenetic relationship with the genera Bacillus, Vibrio, Citrobacter and Escherichia. Moreover, an isolate showing morphological and physiological similarities with the genus Enterococcus was characterised and taxonomically described based on the 16S rDNA sequence. 相似文献
The submarine caves of Cape Palinuro were discovered long ago, but only during the last decades were geological and biological investigations carried out, yielding a large number of reports on this fascinating environment. During the last two years, several samples of water, mud, and/or bacterial mat were collected within the "Grotta Azzurra", and enrichment experiments were performed using peptone, starch, glucose or pullulan as main organic nutrients. Many heterotrophic strains were isolated and most of them grew optimally between 37 and 43 ° C with the addition of 0-2 % NaCl. Growth was usually observed between 10 and 50 ° C the range of growth pH was 4 to 9, and NaCl concentrations up to 10–12 % were tolerated in most cases.
The analysis of 16S rDNA performed with the most representative isolates showed a close phylogenetic relationship with the genera Bacillus, Vibrio, Citrobacter and Escherichia. Moreover, an isolate showing morphological and physiological similarities with the genus Enterococcus was characterised and taxonomically described based on the 16S rDNA sequence. 相似文献
54.
Insaf S. Babiker Mohamed A. A. Mohamed Kaori Komaki Keiichi Ohta Kikuo Kato 《Journal of Oceanography》2004,60(3):553-562
Changes in patterns of undetectability and molar ratios of dissolved nutrients in the euphotic zone of the oligotrophic western
North Atlantic Ocean were investigated utilizing the Bermuda Atlantic Time-series Study (BATS) data set of the US Joint Global
Ocean Flux Study (JGOFS). Our aim was to examine the temporal dynamics of nutrient stocks over a decade (1989∼1998) and to
gain insight into the interactions between the different biotic and abiotic factors underlying BATS. Patterns of nutrient
undetectability clearly revealed the depleted nature of the nutrients in surface water at the BATS location, particularly
phosphorous. The N:P ratio was consistently far above the nominal Redfield ratio (mean, 38.5) but was significantly lower
during the 1993∼1994 period (22.1). Over the same period the proportion of samples depleted in N only increased while the
proportion of samples depleted in P only decreased. This indicates an overall reduction of N relative to P in the surface
water at BATS during the 1993∼1994 period, the reasons for this anomaly, though, are not clear. The correlation analysis between
the biotic and abiotic variables at BATS has indicated some interesting relationships that can help understand some of the
parameters affecting nutrient stocks in the euphotic zone and their consequent impacts on marine biota. Although nutrient
stocks in the oligotrophic environment are limited, they might be subject to interannual variation that may become anomalous
in some cases. These variations might underlay significant feedback mechanisms by affecting marine productivity, the prime
factor controlling the sequestration of atmospheric CO2 by the oceans.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
55.
Keiji Horikawa Masao Minagawa Yoshihisa Kato Masafumi Murayama Seiya Nagao 《Journal of Oceanography》2006,62(4):427-439
N2 fixation is an important biological process that adds new nitrogen to oceans and plays a key role in modulating the oceanic
nitrate inventory. However, it is not known how, when, and where N2 fixation rates have varied in response to past climate changes. This study presents a new record of nitrogen isotopic composition
(δ15N) over the last 83 kyr from a sediment core (KH02-4 SUP8) taken in the Sulu Sea in the western equatorial Pacific region;
data allow the N2 fixation variability in the sea to be reconstructed. Sediments, sinking, and suspended particulate organic matter (POM) all
have lighter isotopic values compared to the δ15N values of substrate nitrate (av. 5.8‰) in North Pacific Intermediate Water. These lighter δ15N values are regarded as reflecting N2 fixation in the Sulu Sea surface water. A δ15N mass balance model shows that N2 fixation rates were significantly enhanced during 54–34 kyr in MIS-3 and MIS-2. It has been speculated that higher interglacial
denitrification rates in the Arabian Sea and the eastern tropical Pacific would have markedly decreased the global oceanic
N inventory and contributed to the increase in N2 fixation in oligotrophic regions, but such a model was not revealed by our study. It is possible that changes in N2 fixation rates in the Sulu Sea were regional response, and accumulation of phosphate in the surface waters due to enhanced
monsoon-driven mixing is thought to have stimulated enhancements of N2 fixation during MIS-3 and MIS-2. 相似文献
56.
Manabu D. Yamanaka Shoichiro Fukao Hiromasa Matsumoto Toru Sato Toshitaka Tsuda Susumu Kato 《Pure and Applied Geophysics》1989,130(2-3):481-495
Marked wavelike variations of the lower stratospheric wind observed on 7–10 May, 1985 by an MST radar in Japan (by the MU radar) are analyzed assuming that they are induced by monochromatic internal inertio-gravity waves. These variations are mainly composed of two modes (periods: 22 and 24 hours), both of which have zonal phase velocities (C
X
) slower than the mean westerly wind (). A statistical analysis of the zonal phase velocity shows thatC
X
above andC
X
below the tropopause jet stream, which is considered to be a vivid proof of wave selection due to the tropospheric mean flow and upward wave emission from the tropopause jet. A comparison between the MU radar results and routine meteorological observations leads to the conclusion that the marked waves appear when the jet stream takes a maximum wind speed. 相似文献
57.
The radial brightness distribution of the quiet Sun at 8.6 mm is synthesized from observations using a sixteen element east-west interferometer in Nagoya. The observed brightness is flat from the disk center to 0.8R
. A slight darkening appeared between 0.8R
and the limb. No evidence of the bright ring near the limb is found. The radio radius at 8.6 mm is 1.015±0.005R
. In addition there exists a coronal component just outside the radio limb. 相似文献
58.
Chemical, optical and X-ray powder data on coexisting anthophyllite and hornblende in an amphibolite are presented. Some chemical features of amphibole pairs are briefly discussed. 相似文献
59.
Fumihiro Kato Masaki Kawabe 《Deep Sea Research Part I: Oceanographic Research Papers》2009,56(12):2077-2087
We conducted full-depth hydrographic observations between 8°50′ and 44°30′N at 165°W in 2003 and analyzed the data together with those from the World Ocean Circulation Experiment and the World Ocean Database, clarifying the water characteristics and deep circulation in the Central and Northeast Pacific Basins. The deep-water characteristics at depths greater than approximately 2000 dbar at 165°W differ among three regions demarcated by the Hawaiian Ridge at around 24°N and the Mendocino Fracture Zone at 37°N: the southern region (10–24°N), central region (24–37°N), and northern region (north of 37°N). Deep water at temperatures below 1.15 °C and depths greater than 4000 dbar is highly stratified in the southern region, weakly stratified in the central region, and largely uniform in the northern region. Among the three regions, near-bottom water immediately east of Clarion Passage in the southern region is coldest (θ<0.90 °C), most saline (S>34.70), highest in dissolved oxygen (O2>4.2 ml l?1), and lowest in silica (Si<135 μmol kg?1). These characteristics of the deep water reflect transport of Lower Circumpolar Deep Water (LCDW) due to a branch current south of the Wake–Necker Ridge that is separated from the eastern branch current of the deep circulation immediately north of 10°N in the Central Pacific Basin. The branch current south of the Wake–Necker Ridge carries LCDW of θ<1.05 °C with a volume transport of 3.7 Sv (1 Sv=106 m3 s?1) into the Northeast Pacific Basin through Horizon and Clarion Passages, mainly through the latter (~3.1 Sv). A small amount of the LCDW flows northward at the western boundary of the Northeast Pacific Basin, joins the branch of deep circulation from the Main Gap of the Emperor Seamounts Chain, and forms an eastward current along the Mendocino Fracture Zone with volume transport of nearly 1 Sv. If this volume transport is typical, a major portion of the LCDW (~3 Sv) carried by the branch current south of the Wake–Necker and Hawaiian Ridges may spread in the southern part of the Northeast Pacific Basin. In the northern region at 165°W, silica maxima are found near the bottom and at 2200 dbar; the minimum between the double maxima occurs at a depth of approximately 4000 dbar (θ~1.15 °C). The geostrophic current north of 39°N in the upper deep layer between 1.15 and 2.2 °C, with reference to the 1.15 °C isotherm, has a westward volume transport of 1.6 Sv at 39–44°30′N, carrying silica-rich North Pacific Deep Water from the northeastern region of the Northeast Pacific Basin to the Northwest Pacific Basin. 相似文献
60.
Keiji Horikawa Masafumi Murayama Masao Minagawa Yoshihisa Kato Takuya Sagawa 《Quaternary Research》2010,73(3):573-582
The n-alkane C31/(C29 + C31) ratios from surface sediments in the eastern equatorial Pacific (EEP) exhibit higher values to the north and lower values to the south across the southern edge (2–4°N) of the Intertropical Convergence Zone (ITCZ). Since plants tend to synthesize longer chain length n-alkanes in response to elevated temperature and/or aridity, the higher C31/(C29 + C31) ratios at northern sites suggest a higher contribution of vegetation under hot and/or dry conditions. This is consistent with the observation that northern sites receive higher levels of plant waxes transported by northeasterly trade winds from northern South America, where hot and dry conditions prevail. Furthermore, from a sediment core covering the past 750 ka (core HY04; 4°N, 95°W) we found that C31/(C29 + C31) ratios exhibit a long-term decrease from MIS (marine oxygen isotope stage) 17 to 13. During this period, the zonal SST (sea-surface temperature) gradient in the equatorial Pacific increased, suggesting an increase in Walker circulation. Such intensified Walker circulation may have enhanced moisture advection from the equatorial Atlantic warm pool to the adjacent northern South America, causing arid regions in northern South America to contract, which may explain long-term decrease in n-alkane chain lengths. 相似文献