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81.
Equipment has been developed to display in colour any circular polarization in the dynamic spectra of solar radio emissions. The potential and limitations of this simple equipment are discussed on the basis of a sample record. Modifications, now under development, to improve the system are described. 相似文献
82.
The rotational temperature of the airglow hydroxyl emissions arising from various schemes of vibrational transitions was obtained by using spectroscopic data from six observational sources. The rotational temperature was found to depend systematically on the quantum number (ν') of the upper vibrational level from which the relevant band originates. It has a doubly degrading characteristic with respect to ν' taking maximal values at ν' = 6 and 9, which exceed considerably the atmospheric temperature. It drops off quickly as ν' decreases from 9 to 7, and then from 6 to 3 after making an abrupt rise at ν' = 6. This ν'-dependence of the rotational temperature is in favor of the hypothesis that there are two routes of excitation of the hydroxyl airglow: O3 + H = OH(ν ? 9) + O2, and HO2 + O = OH(ν ? 6) + O2. The present result implies also that the relaxation time of rotation of OH in the upper mesosphere is as long as 0.1 sec; a value an order of magnitude larger than that inferred in earlier laboratory experiments. 相似文献
83.
Tetsuo Hasegawa Masatoshi Ohishi Masaki Morimoto Hiroko Suzuki Norio Kaifu 《Icarus》1984,60(1):211-214
The search for radio spectral lines from Comet Sugano-Saigusa-Fujikawa (1983e) was conducted using the 45-m telescope of Nobeyama Radio Observatory. The frequency ranges of 44.0–46.0 and 47.5–49.5 GHz were surveyed down to , with a beam size of ~35 arc sec. Upper limits have been established for spectral lines of atomic hydrogen, CS, OCS, SO2, H2CO, CH3OH, HCCCCCN, HCOOCH3, CH3OCH3, and CH3CH2CN. The J = 5?4 line from HCCCN in the vibrational ground state possibly has been detected but not confirmed. The suggested total amount of HCCCN in the coma is consistent with the possible picture that HCCCN is the main parent molecule of CN. 相似文献
84.
Neutrinos represent a new window to the Universe. In this paper we discuss the attempts to detect neutrinos, starting with the Homestake experiment, which showed the deficit of solar neutrinos. The detection of neutrinos from SN 1987A gave a new impetus to neutrino research. By using successive generations of neutrino detectors it was possible to show that the solar neutrino deficit could be explained by a flavor change of massive neutrinos. With the latest detector, kamLAND, it is possible to investigate the interior of the Earth through the detection of geoneutrinos. 相似文献
85.
Biogeochemistry of nitrous oxide in groundwater in a forested ecosystem elucidated by nitrous oxide isotopomer measurements 总被引:3,自引:0,他引:3
K. Koba K. Osaka Y. Tobari S. Toyoda N. Ohte M. Katsuyama N. Suzuki M. Itoh H. Yamagishi M. Kawasaki S.J. Kim N. Yoshida T. Nakajima 《Geochimica et cosmochimica acta》2009,73(11):3115-1037
The biological and physical controls on microbial processes that produce and consume N2O in soils are highly complex. Isotopomer ratios of N2O, with abundance of 14N15N16O, 15N14N16O, and 14N14N18O relative to 14N14N16O, are promising for elucidation of N2O biogeochemistry in an intact ecosystem. Site preference, the nitrogen isotope ratio of the central nitrogen atom minus that of the terminal nitrogen atom, is useful to distinguish between N2O via hydroxylamine oxidation and N2O via nitrite reduction.We applied this isotopomer analysis to a groundwater system in a temperate coniferous-forested ecosystem. Results of a previous study at this location showed that the N2O concentration in groundwater varied greatly according to groundwater chemistry, i.e. NO3−, DOC, and DO, although apportionment of N2O production to nitrification or denitrification was ambiguous. Our isotopic analysis (δ15N and δ18O) of NO3− and N2O implies that denitrification is the dominant production process of N2O, but definitive information is not derived from δ15N and δ18O analysis because of large variations in isotopic fractionations during production and consumption of N2O. However, the N2O site preference and the difference in δ15N between NO3− and N2O indicate that nitrification contributes to total N2O production and that most measured N2O has been subjected to further N2O reduction to N2. The implications of N2O biogeochemistry derived from isotope and isotopomer data differ entirely from those derived from conventional concentration data of DO, NO3−, and N2O. That difference underscores the need to reconsider our understanding of the N cycle in the oxic-anoxic interface. 相似文献
86.
Shin'ichiro Ando Daisuke Nagai 《Monthly notices of the Royal Astronomical Society》2008,385(4):2243-2253
Cosmic rays produced in cluster accretion and merger shocks provide pressure to the intracluster medium (ICM) and affect the mass estimates of galaxy clusters. Although direct evidence for cosmic ray ions in the ICM is still lacking, they produce γ-ray emission through the decay of neutral pions produced in their collisions with ICM nucleons. We investigate the capability of the Gamma-ray Large Area Space Telescope ( GLAST ) and imaging atmospheric Čerenkov telescopes (IACTs) for constraining the cosmic ray pressure contribution to the ICM. We show that GLAST can be used to place stringent upper limits, a few per cent for individual nearby rich clusters, on the ratio of pressures of the cosmic rays and thermal gas. We further show that it is possible to place tight (≲10 per cent) constraints for distant ( z ≲ 0.25) clusters in the case of hard spectrum, by stacking signals from samples of known clusters. The GLAST limits could be made more precise with the constraint on the cosmic ray spectrum potentially provided by IACTs. Future γ-ray observations of clusters can constrain the evolution of cosmic ray energy density, which would have important implications for cosmological tests with upcoming X-ray and Sunyaev–Zel'dovich effect cluster surveys. 相似文献
87.
S. Kida K. Niinuma S. Suzuki T. Tanaka R. Nakanura K. Takefuji N. Matsumura M. Kuniyoshi T. Daishido 《New Astronomy》2008,13(7):519-525
The Nasu Observatory, which is composed of eight 20 m elements, was constructed for observing radio transients over a wide field at 1400 MHz. We report on two radio transients detected in consecutive drift scanning observations at declination 32° over a period of about two months. One of the two transients, WJN J1039+3200, appeared at =10h39m40s±10s, δ=32°±0.4° on March 4, 2005, and the other one, WJN J0645+3200, appeared at =06h45m25s±10s, δ=32°±0.4° on March 24, 2005. Both exhibited flux densities in excess of 1 Jy, and the burst durations were up to two days. Since there are few examples of radio transients outside the Galactic plane, these are very important observations. We have previously reported on four radio transients with features that look like the two transients detected this time. Of these six WJN transients in total, five had a duration of up to two days, and one up to three days. Four of the transients were detected at high Galactic latitude of b > 30°. Counterparts of the six WJN transients included X-ray sources in four events and had a consistency of 66%. The consistency of γ-ray, PGC Galaxy, NVSS, and FIRST sources was concentrated at about 50%. We were not able to find any special features in the counterparts. The distribution was verified by making a log N–log S plot using data for the four previously detected transients and the new ones. As a result, the distribution of the radio transients that we observed might have an isotropic distribution not dependent on Galactic longitude and Galactic latitude. The detection probability was calculated based on the assumption of an isotropic distribution. The 2σ upper probability limit for detection of transients of 1000 mJy or more is 0.0049 [deg−2 yr−1]. We cannot yet identify these two radio transients, because their features are different from any radio bursts observed in the past. 相似文献
88.
Carbonate‐replacement polymetallic mineralization at the Huanzala deposits (9°51′S, 77°00′W) was conducted in two contrasting stages that occurred in almost the same location. Early‐stage mineralization has a relation with a granodiorite porphyry stock, whereas the late‐stage mineralization is genetically associated with quartz porphyry sills. The early stage involved low to intermediate sulfidation Cu–Zn–(Pb) mineralization associated with metasomatic skarn, and the late stage involved high to intermediate sulfidation Cu–Zn–Pb–(Mn) mineralization associated with hydrothermal alteration characterized by paragonitic sericitization. The orebodies are hosted by steeply dipping (approximately 60°NE) Lower Cretaceous carbonate rocks in a relatively narrow range of approximately 4 km in horizontal extent and less than 1 km in depth. The pathway of the early‐stage brine‐derived fluids (300–>400°C, >33 wt% NaCl equivalent) along a plot of log against 1000/T is best explained by the progressive dual decline of the value and the temperature under rock‐buffering conditions; this decline saw the pathway progress through the stability field of pyrrhotite to reach that of pyrite and promoted a decrease in FeS from 14.5 to 1.6 mol% in the sphalerite. In contrast, an explanation for the pathway of the late‐stage fluids (140–290°C, 3–13 wt% NaCl equivalent) is given by an almost isothermal decline at approximately 270°C, with passing through the stability field of pyrite–bornite to reach that of chalcopyrite, promoting an increase in FeS from 0.1 to 1.6 mol% in the sphalerite, suggesting gas‐buffering conditions. The ore formation pressure records in the fluid inclusions illustrate an approximately 2‐km erosion during the roughly 2‐Myr total lifetime of the hydrothermal system. 相似文献
89.
Hidenori Terasaki Keisuke Nishida Satoru Urakawa Yusaku Takubo Soma Kuwabara Yuta Shimoyama Kentaro Uesugi Yoshio Kono Akihisa Takeuchi Yoshio Suzuki Yuji Higo Tadashi Kondo 《Comptes Rendus Geoscience》2019,351(2-3):163-170
A new experimental setup for simultaneous P-wave velocity (VP) and density (ρ) measurements for liquid alloys is developed using ultrasonic and X-ray absorption methods combined with X-ray tomography at high pressures and high temperatures. The new setup allows us to directly determine adiabatic bulk moduli (KS) and to discuss the correlation between the VP and ρ of the liquid sample. We measured VP and ρ of liquid Ni68S32 up to 5.6 GPa and 1045 K using this technique. The effect of pressure on the VP and ρ values of liquid Ni68S32 is similar to that of liquid Fe57S43. (Both compositions correspond to near-eutectic ones.) The obtained KS values are well fitted to the finite strain equation with a value (KS at ambient pressure) of 31.1 GPa and a dKS/dP value of 8.44. The measured VP was found to increase linearly with increasing ρ, as approximated by the relationship: VP [m/s] = 1.29 ρ [kg/m3] – 5726, suggesting that liquid Ni–S follows an empirical linear relationship, Birch's law. The dVP/dρ slope is similar between Ni68S32 and Fe57S43 liquids, while the VP–ρ plot of liquid Ni–S is markedly different from that of liquid Fe–S, which indicates that the effect of Ni on Birch's law is important for understanding the VP–ρ relation of planetary and Moon's molten cores. 相似文献
90.
Yusaku Shimizu Atsushi Ooki Hiroji Onishi Tetsuya Takatsu Seiji Tanaka Yuta Inagaki Kota Suzuki Naoto Kobayashi Yoshihiko Kamei Kenshi Kuma 《Journal of Atmospheric Chemistry》2017,74(2):205-225
Volatile organic iodine compounds (VOIs) emitted from the ocean surface to the air play an important role in atmospheric chemistry. Shipboard observations were conducted in Funka Bay, Hokkaido, Japan, bimonthly or monthly from March 2012 to December 2014, to elucidate the seasonal variations of VOI concentrations in seawater and their sea-to-air iodine fluxes. The bay water exchanges with the open ocean water of the North Pacific twice a year (early spring and autumn). Vertical profiles of CH2I2, CH2ClI, CH3I, and C2H5I concentrations in the bay water were measured bimonthly or monthly within an identified water mass. The VOI concentrations began to increase after early April at the end of the diatom spring bloom, and represented substantial peaks in June or July. The temporal variation of the C2H5I profile, which showed a distinct peak in the bottom layer from April to July, was similar to the PO4 3? variation profile. Correlation between C2H5I and PO4 3? concentrations (r = 0.93) suggests that C2H5I production was associated with degradation of organic matter deposited on the bottom after the spring bloom. CH2I2 and CH2ClI concentrations increased substantially in the surface and subsurface layers (0–60 m) in June or July resulted in a clear seasonal variation of the sea-to-air iodine flux of the VOIs (high in summer or autumn and low in spring). 相似文献