Arbeiten zur Grundcharakterisierung am niedrigaktivierenden Stahl F82H-mod im Vergleich zu OPTIFER

Von japanischer Seite wurde den europäischen Labors Plattenmaterial des niedrigaktivierenden Stahles F82H-mod zur Verfügung gestellt. Vom FZK/IMF werden Untersuchungen zur Grundcharakterisierung durchgeführt, die im Rahmen dieses Berichtes mit den Ergebnissen der europäischen OPTIFER-Versionen verglichen werden. Neben den Kontrollversuchen zur chemischen Zusammensetzung und des Anlieferzustandes wird das Umwandlungs-, Härte- und Anlaßverhalten beschrieben. Die Zugfestigkeitseigenschaften wurden für den Bereich RT bis 700°C und das Kerbschlagzähigkeitsverhalten im Bereich -80° bis +80°C bestimmt. Breiten Raum nehmen die Versuche zum Zeitstandfestigkeits- und Kriechverhalten ein, die im Temperaturbereich 450-700°C z.Zt. den Standzeitbereich bis rd. 15 000 h experimentell abdecken. Auffallend ist die bei einigen Kenngrößen beobachtete große Streubreite der Meßergebnisse, die einen wesentlich breiteren Versuchsumfang als üblich erforderte

Presupernova Structure of Massive Stars

Issues concerning the structure and evolution of core collapse progenitor stars are discussed with an emphasis on interior evolution. We describe a program designed to investigate the transport and mixing processes associated with stellar turbulence, arguably the greatest source of uncertainty in progenitor structure, besides mass loss, at the time of core collapse. An effort to use precision observations of stellar parameters to constrain theoretical modeling is also described.Comment: Proceedings for invited talk at High Energy Density Laboratory Astrophysics conference, Caltech, March 2010. Special issue of Astrophysics and Space Science, submitted for peer review: 7 pages, 3 figure

Nature's Frontiers: Achieving Sustainability, Efficiency, and Prosperity with Natural Capital

The great expansion of economic activity since the end of World War II has caused an unprecedented rise in living standards, but it has also caused rapid changes in earth systems. Nearly all types of natural capital—the world’s stock of resources and services provided by nature—are in decline. Clean air, abundant and clean water, fertile soils, productive fisheries, dense forests, and healthy oceans are critical for healthy lives and healthy economies. Mounting pressures, however, suggest that the trend of declining natural capital may cast a long shadow into the future. "Nature’s Frontiers: Achieving Sustainability, Efficiency, and Prosperity with Natural Capital" presents a novel approach to address these foundational challenges of sustainability. A methodology combining innovative science, new data sources, and cutting-edge biophysical and economic models builds sustainable resource efficiency frontiers to assess how countries can sustainably use their natural capital more efficiently. The analysis provides recommendations on how countries can better use their natural capital to achieve their economic and environ mental goals. The report indicates that significant efficiency gaps exist in nearly every country. Closing these gaps can address many of the world’s pressing economic and environmental problems—economic productivity, health, food and water security, and climate change. Although the approach outlined in this report will entail demanding policy reforms, the costs of inaction will be far higher

Menus for Feeding Black Holes

Black holes are the ultimate prisons of the Universe, regions of spacetime where the enormous gravity prohibits matter or even light to escape to infinity. Yet, matter falling toward the black holes may shine spectacularly, generating the strongest source of radiation. These sources provide us with astrophysical laboratories of extreme physical conditions that cannot be realized on Earth. This chapter offers a review of the basic menus for feeding matter onto black holes and discusses their observational implications.Comment: 27 pages. Accepted for publication in Space Science Reviews. Also to appear in hard cover in the Space Sciences Series of ISSI "The Physics of Accretion onto Black Holes" (Springer Publisher

Acoustic and optical variations during rapid downward motion episodes in the deep north-western Mediterranean Sea

An Acoustic Doppler Current Profiler (ADCP) was moored at the deep-sea site of the ANTARES neutrino telescope near Toulon, France, thus providing a unique opportunity to compare high-resolution acoustic and optical observations between 70 and 170 m above the sea bed at 2475 m. The ADCP measured downward vertical currents of magnitudes up to 0.03 m s-1 in late winter and early spring 2006. In the same period, observations were made of enhanced levels of acoustic reflection, interpreted as suspended particles including zooplankton, by a factor of about 10 and of horizontal currents reaching 0.35 m s-1. These observations coincided with high light levels detected by the telescope, interpreted as increased bioluminescence. During winter 2006 deep dense-water formation occurred in the Ligurian subbasin, thus providing a possible explanation for these observations. However, the 10-20 days quasi-periodic episodes of high levels of acoustic reflection, light and large vertical currents continuing into the summer are not direct evidence of this process. It is hypothesized that the main process allowing for suspended material to be moved vertically later in the year is local advection, linked with topographic boundary current instabilities along the rim of the 'Northern Current'.Comment: 30 pages, 7 figure

Dust in Supernovae and Supernova Remnants I : Formation Scenarios

Supernovae are considered as prime sources of dust in space. Observations of local supernovae over the past couple of decades have detected the presence of dust in supernova ejecta. The reddening of the high redshift quasars also indicate the presence of large masses of dust in early galaxies. Considering the top heavy IMF in the early galaxies, supernovae are assumed to be the major contributor to these large amounts of dust. However, the composition and morphology of dust grains formed in a supernova ejecta is yet to be understood with clarity. Moreover, the dust masses inferred from observations in mid-infrared and submillimeter wavelength regimes differ by two orders of magnitude or more. Therefore, the mechanism responsible for the synthesis of molecules and dust in such environments plays a crucial role in studying the evolution of cosmic dust in galaxies. This review summarises our current knowledge of dust formation in supernova ejecta and tries to quantify the role of supernovae as dust producers in a galaxy.Peer reviewe

Arbeiten zur Grundcharakterisierung am niedrigaktivierenden Stahl F82H-mod im Vergleich zu OPTIFER

Low-activated F82H-model steel plate material was made available to the European laboratories by the Japanese side. Basic characterization work is being performed by FZK/IMF. In the present report, the results obtained shall be compared with the European OPTIFER types. The chemical composition and the state as delivered are controlled. In addition, transformation, hardness and tempering behaviors shall be described. Tensile strength and impact bending strength were determined in the ranges of RT to 700 C and -80 C to +80 C, respectively. Particular attention is paid to the creep strength behavior. The current tests cover the range of up to 15000 h at temperatures ranging from 450 to 700 C. It can be noticed that the results measured for some parameters are subject to considerable scattering. As compared to previous tests, the experimental scope therefore had to be increased significantly. (orig.)Von japanischer Seite wurde den europaeischen Labors Plattenmaterial des niedrigaktivierenden Stahles F82H-mod zur Verfuegung gestellt. Vom FZK/IMF werden Untersuchungen zur Grundcharakterisierung durchgefuehrt, die im Rahmen dieses Berichtes mit den Ergebnissen der europaeischen OPTIFER-Versionen verglichen werden. Neben den Kontrollversuchen zur chemischen Zusammensetzung und des Anlieferzustandes wird das Umwandlungs-, Haerte- und Anlassverhalten beschrieben. Die Zugfestigkeitseigenschaften wurden fuer den Bereich RT bis 700 C und das Kerbschlagzaehigkeitsverhalten im Bereich -80 bis +80 C bestimmt. Breiten Raum nehmen die Versuche zum Zeitstandfestigkeits- und Kriechverhalten ein, die im Temperaturbereich 450-700 C z.Zt. den Standzeitbereich bis rd. 15 000 h experimentell abdecken. Auffallend ist die bei einigen Kenngroessen beobachtete grosse Streubreite der Messergebnisse, die einen wesentlich breiteren Versuchsumfang als ueblich erforderte. (orig.)Available from TIB Hannover: ZA 5141(6008) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Organic matter in space: from star dust to the Solar System

Organic compounds of high degree of complexity are now known to be widespread in the Universe, ranging from objects in our Solar System to distant galaxies. Through the techniques of millimeter-wave spectroscopy, over 140 molecules have been identified through their rotational transitions. Space infrared spectroscopy has detected the stretching and bending modes of compounds with aromatic and aliphatic structures. Analyses of samples of meteorites, comets, asteroids, and interplanetary dust also revealed a rich content of organic substances, some of which could be of extra-solar origin. We review the current state of understanding of the origin, evolution, nature, and distribution of organic matter in space. Also discussed are a number of unexplained astronomical phenomena whose origins could be traced to organic carriers. © 2008 Springer Science+Business Media B.V.link_to_subscribed_fulltex