Stellar dynamics in the Galactic Centre: proper motions and anisotropy     

R. Genzel  C. Pichon  A. Eckart  O. E. Gerhard  T. Ott 《Monthly notices of the Royal Astronomical Society》2000,317(2):348-374

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NOBLE GASES AND THE CLASSIFICATION OF BRACHINA     

Ulrich Ott  Hans-Peter Lhr  Friedrich Begemann 《Meteoritics & planetary science》1985,20(1):69-78

Noble-gas systematics show that Brachino is not a member of the SNC-group of meteorites. The whole-rock K-Ar gas retention age is (3.11 ± 0.07) AE as compared to the 1.3 AE solidification ages of SNCs; the content of radiogenic¹²⁹ Xe* of (3.47 ±. 15) × 10^?10 cm³ STP/g is about two orders of magnitude higher, and the¹²⁹ Xe/¹³² Xe ratio (11.0), the ratio of radiogenic¹²⁹ Xe* to fissiogenic¹³⁶ Xe_f (300), and the ratio³⁶ Ar/¹³² Xe in the trapped gases are about one order of magnitude higher than observed for SNCs. The same evidence argues strongly against any simple genetic relationship with eucrites. The noble-gas abundance pattern resembles closely that in silicate inclusions from the iron meteorites Campo del Cielo and Udei Station. Abundances of cosmic-ray produced³ He and²¹ Ne (5.7 and. 99 × 10^?8 cm³ STP/g, resp.) indicate an exposure age of ～ 2.4 Ma. Irradiation conditions appear to have been perfectly normal except for an unaccountably low content of spallogenic ³⁸Ar. Losses by diffusion of radiogenic⁴ He are severe; they must have occurred at or before the onset of the exposure of the meteoroid to the cosmic radiation.  相似文献   

Assessment of present and future nitrogen loads, water quality, and seagrass (Thalassia testudinum) depth distribution in Lemon Bay, Florida     

David A. Tomasko  Denise L. Bristol  Judith A. Ott 《Estuaries and Coasts》2001,24(6):926-938

Nitrogen loads into Lemon Bay, Florida were modeled to have increased ca. 59% between pre-development (i.e., 1850) estimates (5.3 kg TN ha⁻¹ yr⁻¹. and estimates for the year 1995 (8.4 kg TN ha⁻¹ yr⁻¹). By the year 2010, nitrogen loads are predicted to increase an additional 45% or 58%, depending upon progress being made toward replacing older septic tank systems with centralized sewerage (nitrogen loads of 12.2 and 13.3 kg TN ha⁻¹ yr⁻¹, respectively). Using 1995 estimates, nonpoint sources (stormwater runoff) are throught to be responsible for ca. 76% of the annual nitrogen load, followed by septic tank systems (14%), rainfall (10%), and an insignificant load from baseflow. Based on an empirically-derived nitrogen load:chlorophylla relationship developed for a portion of nearby Tampa Bay, a 45% increase in nitrogen loads into Lemon Bay could result in a 29% increase in annual average chlorophylla concentrations. Using the estimate of a 29% increase in future chlorophylla concentrations, an empirically-derived optical model for Lemon Bay suggests that light attenuation coefficients in the bay would increase ca. 9%, and the average depth limit ofThalassia testudinum in Lemon Bay would decrease by ca. 24%.  相似文献   

Lovelock, J.E.: Unsere Erde wird überleben. Gaia - Eine optimistische Ökologie. Aus dem Englischen von Marianne Oertl.     

Jörg A.  Ott 《Marine Ecology》1982,3(3):279-280

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Tackling the Sulfide Gradient: A Novel Strategy Involving Marine Nematodes and Chemoautotrophic Ectosymbionts   总被引：3，自引：0，他引：3  

J. A. Ott    R. Novak    F. Schiemer    U .Hentschel    M. Nebelsick  M. Polz 《Marine Ecology》1991,12(3):261-279

Abstract. The Stilbonemutinue (marine free-living nematodes) arc remarkable for cctosymbiotic bacteria, which cover the greatest part of their body in a highly ordered and species specific pattern. Using SEM we describe the main types of symbiotic cover and give evidence for the role of the bacteria in the nutrition of their host on the basis of stable carbon isotope ratios. In experimental systems the worms migrated repeatedly across a sulfide gradient during 12 h when sulfide concentrations were low, but stayed above the sulfide maximum at high concentrations. The migration across the chemocline exposes the symbionts alternately to reduced sulfur compounds and oxygen; this constitutes an alternative strategy to the ventilation/circulation systems in symbiotic macrofauna from sulfidic habitats.  相似文献   

Synthesis of refractory metal nuggets and constraints on the thermal histories of nugget‐bearing Ca,Al‐rich inclusions          下载免费PDF全文

D. Schwander  S. Buhre  G. Schönhense  U. Ott 《Meteoritics & planetary science》2015,50(5):893-903

Tiny refractory metal nuggets are mainly observed inside Ca, Al‐rich inclusions (CAIs) from chondritic meteorites and are commonly assumed to be condensates from a solar composition gas. However, recent detailed studies of metal nugget compositions and their comparison with predictions from condensation show that the observed abundance patterns are extremely difficult to achieve in this way. As a test for the proposed alternative, precipitation from a silicate liquid, we conducted melting experiments, in which nine different refractory metals (nugget components) were equilibrated with each other along with a CAI‐like liquid at reducing conditions. When quenched, minerals similar to those in CAIs formed from such liquids including refractory metal nuggets exhibiting compositions and appearances similar to those of the meteoritic nuggets. The run products and their comparison with a meteoritic nugget‐bearing CAI is evidence for formation of refractory metal nuggets during cooling of Ca, Al‐rich liquids at rates about 1000°/40 s (in the interval from 1900 to 900 °C). To achieve the formation of refractory metal nuggets and the textures observed in the host inclusions, during cooling the rate probably changed. Refractory metal nuggets apparently formed during quenching before spinel crystallized.  相似文献   

August Tammekann in Estonian and Finnish geography     

Ott Kurs 《GeoJournal》1995,36(4):428-428

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Indigenous Finnic population of NW Russia     

Ott Kurs 《GeoJournal》1994,34(4):447-456

In the Middle Ages, before the colonization of eastern Slaves, the area between the Upper Volga and the White Sea was settled bv Finno-Ugric population. In the northern belt lived Sami (Lapp), in the southern Vepsian, Karelian and other Baltic-Finnic tribes. Those peoples were baptized by the Russian orthodox church and incorporated into the Russian state. As a result of Russian-Swedish wars Karelia was divided and split up and Karelians were dispersed. At the beginning of the Soviet period national territorial divisions were organized for the largest groups of Karelians in Eastern and Tver Karelia. Certain territorial divisions were also established for the Vepsians and the Kola Sami. Nowadays, after half a century (about 1937–1987) of Russification and social oppression, all these minority groups are rebuilding their ethnic identity and cultural institutions. Due to earlier repressions and the assimilation policy of Soviet power, the viability of these ethnic minorities is still smaller than it was before World War II. While the numbers of Karelians and Vepsians in the 1930s were 250,000 and 35,000 respectively, but in 1989, the numbers were only 124,900 and 12,100. The total number of the Russian Sami (approximately 1,800) has not changed but the role of the Sami in the Kola Lapland is now insignificant.  相似文献   

Ingria: The broken landbridge between Estonia and Finland     

Ott Kurs 《GeoJournal》1994,33(1):107-113

Ingria, or Ingermanland, is the historical province between Estonia and Finland, in the vicinity of the present St. Petersburg. Ingria is the ancient homeland of the Baltic Finns — the Votians, Ingrians and Ingrian Finns. The oldest inhabitants of Ingria were the Votians and Ingrians who were christianized by the orthodex popes. By language and culture, the Votians are close to the Estonians; and the Ingrians to the Karelians and the easternmost Finnish people. In the 17th century in Ingria, one part of the Votians and the Ingrians together with the Finnish-speaking ethnic groups who had immigrated from East Finland, began to evolve into a group of Finns who professed the Lutheran faith and came to call themselves Ingrian Finns. They succeeded in surviving as a viable ethnic group until the end of the 1920s. After that the Soviet Union pursued genocidal policy towards them. Before and after World War II the indigenous people of Ingria were deported to different parts of the Soviet Union. Now the Union of Ingrian Finns is working for the right of the Ingrian Finns to return to their homes in St. Petersburg and the Leningrad Oblast (Region). Nowadays the remaining Ingrian Finns live in different parts of the world. In 1989 16,622 Finns were recorded as living in Estonia, where they are organized into 12 societies.  相似文献   

Noble-gas-rich separates from the Allende meteorite     

Ulrich Ott  Ruth Mack 《Geochimica et cosmochimica acta》1981,45(10):1751-1788

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