Amino acids derived from Titan tholins     

Khare BN  Sagan C  Ogino H  Nagy B  Er C  Schram KH  Arakawa ET 《Icarus》1986,68(1):176-184

An organic heteropolymer (Titan tholin) was produced by continuous dc discharge through a 0.9 N2/0.1 CH4 gas mixture at 0.2 mbar pressure, roughly simulating the cloudtop atmosphere of Titan. Treatment of this tholin with 6N HCl yielded 16 amino acids by gas chromatography after derivatization of N-trifluroacetyl isopropyl esters on two different capillary columns. Identifications were confirmed by GC/MS. Glycine, aspartic acid, and alpha- and beta-alanine were produced in greatest abundance; the total yield of amino acids was approximately 10(-2), approximately equal to the yield of urea. The presence of "nonbiological" amino acids, the absence of serine, and the fact that the amino acids are racemic within experimental error together indicate that these molecules are not due to microbial or other contamination, but are derived from the tholin. In addition to the HCN, HC2CN, and (CN)2 found by Voyager, nitriles and aminonitriles should be sought in the Titanian atmosphere and, eventually, amino acids on the surface. These results suggest that episodes of liquid water in the past or future of Titan might lead to major further steps in prebiological organic chemistry on that body.  相似文献   

The anticyclonic eddies just south of jet stream     

H. Arakawa 《Meteorology and Atmospheric Physics》1952,5(1):1-4

Summary The importance of the hydrodynamic instability for the formation of anticyclonic eddies just south of westerly jet stream in the middle latitudes is pointed out. Finally, the author would like to call attention for his earlier works on dynamic instability in 1941.

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Zusammenfassung Die Bedeutung der hydrodynamischen Instabilität für die Bildung antizyklonaler Wirbel direkt südlich des westlichen Freistrahlstromes in mittleren Breiten wird dargelegt. Ferner macht der Verfasser auf seine früheren Untersuchungen von 1941 über dynamische Instabilität aufmerksam.

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Résumé L'auteur montre l'importance de l'instabilité hydrodynamique pour la formation de tourbillons anticycloniques immédiatement au Sud du courant d'Ouest (jet stream) aux latitudes moyennes. Il rappelle ensuite ses précédentes recherches de 1941 sur l'instabilité dynamique.

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With 2 figures.  相似文献   

Zonal wind-profile between the pole and the equator given by a single expression     

H. Arakawa 《Meteorology and Atmospheric Physics》1952,5(2):129-135

The mechanism of the maintenance of the mean zonal circulation of the atmosphere is discussed from the point of view of vorticity transfer and vorticity generation by atmospheric disturbance. The method of analysis used is quite similar with that given byA. Ångström which offers a simple explanation for the mean temperature distribution over the surface of the earth. The annual mean zonal winds over the earth are expressed in a single expression, whereas the zonal wind distribution given byRossby, Kasahara andKuo have all been given for the polar cap and the tropical region separately. The general trends of the latitude variation of the zonal winds computed here fit the observations quite well.

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Zusammenfassung Der Mechanismus der Erhaltung der mittleren zonalen Zirkulation der Atmosphäre wird unter dem Gesichtspunkt der Übertragung und der Neubildung der Wirbelstärke (vorticity) durch atmosphärische Störungen diskutiert. Die zur Analyse benützte Methode ist ähnlich dem vonA. Ångström angegebenen Verfahren, das eine einfache Erklärung für die mittlere Temperaturverteilung über die Erdoberfläche bietet. Die mittleren jährlichen zonalen Winde werden über die ganze Erde durch einen einzigen Ausdruck wiedergegeben, während die vonRossby, Kasahara undKuo angegebenen zonalen Windverteilungen für die Polarregion und das Tropengebiet getrennt berechnet sind. Die hier berechnete allgemeine Tendenz der Breitenvariation der zonalen Winde stimmt mit den Beobachtungen recht gut überein.

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Résumé On examine le mécanisme de l'entretien, de la circulation zonale moyenne de l'atmosphère du point de vue du transfert et de la régénération de la force tourbillonnaire (vorticity) par des perturbations atmosphériques. La méthode d'analyse utilisée est analogue au procédé indiqué parA. Ångström qui fournit une explication simple de la distribution moyenne de la température à la surface du globe. Une seule formule exprime les vents zonaux moyens annuels sur toute la terre, tandis que l'on calcule séparément les répartitions zonales des régions polaire et tropicale données parRossby, Kasahara etKuo. La tendance générale de variation des vents zonaux selon la latitude est en accord satisfaisant avec les faits observés.

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With 1 figure.  相似文献   

Phugoid motion of whirlwinds in the atmosphere     

Dr. H. Arakawa 《Pure and Applied Geophysics》1952,22(3-4):171-173

Summary The movements of whirlwinds are discussed along the line of the phugoid theory, and it is concluded that the path of whirlwinds has the shape of a trochoid.  相似文献   

Algal Growth Potential and the limiting nutrient in Mikawa Bay     

Masao Kondo  Tsutomu Sakai  Hajime Yamamoto  Yukio Arakawa 《Journal of Oceanography》1984,40(5):391-396

The Algal Growth Potential (AGP) of water samples collected off Gamagori in Mikawa Bay was measured from May 1978 through February 1979, and the limiting nutrient was determined using regression analysis and enrichment bioassays. The surface and bottom water samples had AGP that produced increments of chemical oxygen demand (COD) of 2.1 mg l^–1 and 3.1 mg l^–1, respectively, on average. These values ofCOD correspond to 46% and 97% of the average COD values of the raw water samples at the surface and bottom, respectively. Seasonal changes of AGP showed a close correlation with those of dissolved inorganic nitrogen (DIN) concentration. Enrichment bioassays showed that DIN was the most deficient nutrient. The DIN:phosphate-phosphorus (PO₄ ^3–-P) ratios and DIN: dissolved phosphorus (DP) ratios in the water samples were below the cellular N:P ratios of the natural algal populations. These results suggest that AGP was mainly limited by DIN concentration.  相似文献   

Optical constants of organic tholins produced in a simulated Titanian atmosphere: From soft x-ray to microwave frequencies     

B.N. Khare  Carl Sagan  E.T. Arakawa  F. Suits  T.A. Callcott  M.W. Williams 《Icarus》1984,60(1):127-137

As part of a continuing series of experiments on the production of dark reddish organic solids, called tholins, by irradiation of cosmically abundant reducing gases, the synthesis from a simulated Titanian atmosphere of a tholin with a visible reflection spectrum similar to that of the high altitude aerosols responsible for the albedo and reddish color of Titan has been reported Sagan and Khare, 1981, Sagan and Khare, 1982, Orig. Life. 12, 280) and [C. Sagan, B. N. Khare, and J. Lewis, in press. In Saturn (M. S. Matthews and T. Gehrels, Eds.), Univ. of Arizona Press, Tucson]. The determination of the real (n) and imaginary (k) parts of the complex refractive index of thin films of such tholin prepared by continuous D.C. discharge through a 0.9 N₂/0.1 CH₄ gas mixture at 0.2 mb are reported. For $\text{250}\text{A}\text{?}\text{≤ γ ≤ 1000 μ}\text{m}\text{, n}\text{and}\text{k}$ have been determined from a combination of transmittance, specular reflectance, interferometric, Brewster angle, and ellipsometric polarization measurements; experimental uncertainties in n are estimated to be ±0.5, and in k ± 30%. Values of n(?1.65) and k (?0.004 to 0.08) in the visible range are consistent with deductions made by ground-based and spacecraft observations of Titan. Maximum values of k (?0.8) are near 1000 Å, and minimum values (?4 × 10^?4) are near 1.5 μm. Many infrared absorption features are present in k(γ), including the 4.6-μm nitrile band.  相似文献   

La stratigraphie du Pleistocène supérieur et de l'Holocène dans le Golfe de Gascogne: Essai de synthèse des critères actuellement utilisables     

MICHELLE CARALP  JOSETTE DUPRAT  JEAN MOYES ET  CLAUDE PUJOL 《Boreas: An International Journal of Quaternary Research》1974,3(1):35-40

Using analysis of marines cores from the Bay of Biscay as a basis, a system of different episodes of the Upper Pleistocene and the Holocene in the area of the Bay is presented. These episodes are characterized by several sedimentological and micropaleontological observations and particularly by the analysis of the coiling ratio of a few species of planktonic foraminifera. From the cores it is thus possible to determine the Holocene, the Würmian with its four glacial and three interglacial stages, and, at the base of the last glacial stage, the Riss-Würm interglacial or its upper level.  相似文献   

Paléoclimatologie et stratigraphie du Quaternaire terminal du Golfe de Gascogne déduites de l'analyse des Foraminifères planctoniques et des ensenibles sporopolliniques des sédinients marins     

CLAUDE PUJOL ET  JEAN-LOUIS TURON 《Boreas: An International Journal of Quaternary Research》1974,3(3):99-104

The stratigraphy of the Upper Quaternary in the Bay of Biscay based on planktie Fotaminifera is compared to that deduced by palynological study in the same matine core. An identical paleoclimatic interpretation is observed. However, the study of the palynological association has permitted the observation of several climatic variations in the terminal Würmian stages and in the Holocene. On the basis of the analysis, a correlation has been established in the Flolocene between the Boreal-Atlantic limit and the two previous phases recognized by the planktie Foraminifera.  相似文献   

Remarkable winters in Japan from the seventh century     

Dr. H. Arakawa 《Pure and Applied Geophysics》1955,30(1):144-146

Summary In order to compare remarkable winters in Japan with those in Western Europe, chronological list of remarkable winters from the distant past up to the present is given. The correspondence between them is not close.  相似文献   

Recovery of entire shocked samples in a range of pressure from ~100 GPa to Hugoniot elastic limit          下载免费PDF全文

Keita Nagaki  Toshihiko Kadono  Tatsuhiro Sakaiya  Tadashi Kondo  Kosuke Kurosawa  Yoichiro Hironaka  Keisuke Shigemori  Masahiko Arakawa 《Meteoritics & planetary science》2016,51(6):1153-1162

We carried out laser shock experiments and wholly recovered shocked olivine and quartz samples. We investigated the petrographic features based on optical micrographs of sliced samples and found that each recovered sample comprises three regions, I (optically dark), II (opaque), and III (transparent). Scanning electron microscopy combined with electron backscattered diffraction shows that there are no crystal features in the region I; the materials in the region I have once melted. Moreover, numerical calculations performed with the iSALE shock physics code suggest that the boundary between regions II and III corresponds to Hugoniot elastic limit (HEL). Thus, we succeeded in the recovery of the entire shocked samples experienced over a wide range of pressures from HEL (~10 GPa) to melting pressure (~100 GPa) in a hierarchical order.  相似文献