Hydrothermale Dolomitisierung im Kauffunger Kalkstein (Paläozoikum - W-Sudeten, Polen

Within the Kauffung Limestone dolomite bodies related to volcanic contacts occure and are interpreted as a post-Variscan, hydrothermal volcanogenic formation. Two genetic dolomite types are discernible: a pervasive replacement saddle dolomite and a cavity filling saddle dolomite cement. Micro texture and oxygen isotopy of both dolomite types refer to heightened temperatures of formation. The ocurrence of the dolomite in contact to cross-cutting rhyolithic dikes points to a close petrogenetic relation. Dolomite bodies and rhyolithic injections in contrast to the rock wall are characterized by a distinctive cavernous texture, so that a prekinematic genesis is excluded. The formation of replacement saddle dolomite and saddle dolomite cement altogether are considered as a concomitant phenomenon of the Permo-Carboniferous volcanism widespread in the Bober-Katzbach Mountains.Innerhalb des Kauffunger Kalksteins treten an vulkanische Kontakthöfe gebundene Dolomit-Körper auf, die als post-varistische, hydrothermale Bildung interpretiert werden. Genetisch lassen sich zwei Dolomit-Typen unterscheiden: ein pervasiver Ersatzsatteldolomit und ein hohlraumfüllender Satteldolomit-Zement. Mikrogefüge und Sauerstoffisotopie beider Dolomit-Typen weisen auf erhöhte Bildungstemperaturen hin. Das Auftreten des Dolomits in Kontakthöfen querschlägi-ger rhyolithischer Gänge läßt auf eine enge petrogenetische Beziehung schließen. Dolomitkörper und rhyolithische Injektionen sind im Gegensatz zum Nebengestein durch ein auffallend kavernöses Gefüge gekennzeichnet, so daß eine präkinematische Genese ausgeschlossen wird. Die Bildung von Ersatzsatteldolomit und Satteldolomit-Zement wird insgesamt als Begleiterscheinung des im Bober-Katzbach-Gebirge weit verbreiteten Permokarbon-zeitlichen Vulkanismus angesehen

Das Lorca-Becken (Obermiozän, SE-Spanien) : Faziesinterpretation, Sequenzstratigraphie, Beckenanalyse

[no abstract

He and Ne ages of large presolar silicon carbide grains: Solving the recoil problem

Knowledge about the age of presolar grains provides important insights into Galactic chemical evolution and the dynamics of grain formation and destruction processes in the Galaxy. Determination from the abundance of cosmic ray interaction products is straightforward, but in the past has suffered from uncertainties in correcting for recoil losses of spallation products. The problem is less serious in a class of large (tens of micrometer) grains. We describe the correction procedure and summarise results for He and Ne ages of presolar SiC "Jumbo" grains that range from close to zero to ~850 Myr, with the majority being less than 200 Myr. We also discuss the possibility of extending our approach to the majority of smaller SiC grains and explore possible contributions from trapping of cosmic rays.Comment: Publications of the Astronomical Society of Australia, Contribution to PASA special volume "The Origin of Elements Heavier than Iron in honor of the 70th birthday of Roberto Gallino

He and Ne Ages of Large Presolar Silicon Carbide Grains: Solving the Recoil Problem

Knowledge about the age of presolar grains provides important insights into Galactic chemical evolution and the dynamics of grain formation and destruction processes in the Galaxy. Determination from the abundance of cosmic ray interaction products is straightforward, but in the past has suffered from uncertainties in correcting for recoil losses of spallation products. The problem is less serious in a class of large (tens of μm) grains. We describe the correction procedure and summarise results for He and Ne ages of presolar SiC ‘Jumbo' grains that range from close to zero to ∼850 Myr, with the majority being less than 200 Myr. We also discuss the possibility of extending our approach to the majority of smaller SiC grains and explore possible contributions from trapping of cosmic ray

Movement and adjustment in twentieth-century Western writing

Published in Pacific historical review, volume 72, number 3, pages 393-404Western American literature in the twentieth century has effectively mirrored life in the region. The West has for centuries seen more geographic movement, and accompanying cultural adjustment, than other American regions. These themes of movement and adjustment have dominated western writing. Literary historians’ frameworks for categorizing and analyzing this writing have emphasized a tidy process of organic development in western writing, from “frontier fiction” to more mature “regional writing,” or from frontier to regional to post- regional literature. Such models underestimate the degree to which movement and adjustment continued to shape western writing in the twentieth century and tend to separate literature produced by white Europeans from that of other cultural groups. This essay suggests that the more fluid movement and adjustment model can better illuminate the connections between ostensibly separate cultural literary streams

Final report on LDRD project 105967 : exploring the increase in GaAs photodiode responsivity with increased neutron fluence.

A previous LDRD studying radiation hardened optoelectronic components for space-based applications led to the result that increased neutron irradiation from a fast-burst reactor caused increased responsivity in GaAs photodiodes up to a total fluence of 4.4 x 10{sup 13} neutrons/cm{sup 2} (1 MeV Eq., Si). The silicon photodiodes experienced significant degradation. Scientific literature shows that neutrons can both cause defects as well as potentially remove defects in an annealing-like process in GaAs. Though there has been some modeling that suggests how fabrication and radiation-induced defects can migrate to surfaces and interfaces in GaAs and lead to an ordering effect, it is important to consider how these processes affect the performance of devices, such as the basic GaAs p-i-n photodiode. In this LDRD, we manufactured GaAs photodiodes at the MESA facility, irradiated them with electrons and neutrons at the White Sands Missile Range Linac and Fast Burst Reactor, and performed measurements to show the effect of irradiation on dark current, responsivity and high-speed bandwidth

Modular metabolite assembly in C. elegans lysosome-related organelles

Signaling molecules derived from attachment of diverse primary metabolic building blocks to ascarosides play a central role in the life history of C. elegans and other nematodes; however, many aspects of their biogenesis remain unclear. Using comparative metabolomics, we show that lysosome-related organelles (LROs) are required for biosynthesis of most modular ascarosides as well as previously undescribed modular glucosides. Both modular glucosides and ascarosides are derived from highly selective assembly of moieties from nucleoside, amino acid, neurotransmitter, and lipid metabolism. We further show that cholinesterase (cest) homologs that localize to the LROs are required for assembly of both modular ascarosides and glucosides, mediating formation of ester and amide linkages between subsets of building blocks. Their specific biosynthesis suggests that modular glucosides, like ascarosides, serve dedicated signaling functions. Further exploration of LRO function and cest homologs in C. elegans and other animals may reveal additional new compound families and signaling paradigms

Modular metabolite assembly in C. elegans lysosome-related organelles

Signaling molecules derived from attachment of diverse primary metabolic building blocks to ascarosides play a central role in the life history of C. elegans and other nematodes; however, many aspects of their biogenesis remain unclear. Using comparative metabolomics, we show that lysosome-related organelles (LROs) are required for biosynthesis of most modular ascarosides as well as previously undescribed modular glucosides. Both modular glucosides and ascarosides are derived from highly selective assembly of moieties from nucleoside, amino acid, neurotransmitter, and lipid metabolism. We further show that cholinesterase (cest) homologs that localize to the LROs are required for assembly of both modular ascarosides and glucosides, mediating formation of ester and amide linkages between subsets of building blocks. Their specific biosynthesis suggests that modular glucosides, like ascarosides, serve dedicated signaling functions. Further exploration of LRO function and cest homologs in C. elegans and other animals may reveal additional new compound families and signaling paradigms

Radiatively Inefficient Accretion in Nearby Galaxies

We use new central stellar velocity dispersions and nuclear X-ray and Halpha luminosities for the Palomar survey of nearby galaxies to investigate the distribution of nuclear bolometric luminosities and Eddington ratios for their central black holes (BHs). This information helps to constrain the nature of their accretion flows and the physical drivers that control the spectral diversity of nearby active galactic nuclei. The characteristic values of the bolometric luminosities and Eddington ratios, which span over 7-8 orders of magnitude, from L_bol < 10^37 to 3 X 10^44 erg/s and L_bol/L_Edd ~ 10^-9 to 10^-1, vary systematically with nuclear spectral classification, increasing along the sequence absorption-line nuclei --> transition objects --> LINERs --> Seyferts. The Eddington ratio also increases from early-type to late-type galaxies. We show that the very modest accretion rates inferred from the nuclear luminosities can be readily supplied through local mass loss from evolved stars and Bondi accretion of hot gas, without appealing to additional fueling mechanisms such as angular momentum transport on larger scales. Indeed, we argue that the fuel reservoir generated by local processes should produce far more active nuclei than is actually observed. This generic luminosity-deficit problem suggests that the radiative efficiency in these systems is much less than the canonical value of 0.1 for traditional optically thick, geometrically thin accretion disks. The observed values of L_bol/L_Edd, all substantially below unity, further support the hypothesis that massive BHs in most nearby galaxies reside in a low or quiescent state, sustained by accretion through a radiatively inefficient mode.Comment: To appear in ApJ, 15 pages, 4 figure

Modular metabolite assembly in Caenorhabditis elegans depends on carboxylesterases and formation of lysosome-related organelles

Signaling molecules derived from attachment of diverse metabolic building blocks to ascarosides play a central role in the life history of C. elegans and other nematodes; however, many aspects of their biogenesis remain unclear. Using comparative metabolomics, we show that a pathway mediating formation of intestinal lysosome-related organelles (LROs) is required for biosynthesis of most modular ascarosides as well as previously undescribed modular glucosides. Similar to modular ascarosides, the modular glucosides are derived from highly selective assembly of moieties from nucleoside, amino acid, neurotransmitter, and lipid metabolism, suggesting that modular glucosides, like the ascarosides, may serve signaling functions. We further show that carboxylesterases that localize to intestinal organelles are required for the assembly of both modular ascarosides and glucosides via ester and amide linkages. Further exploration of LRO function and carboxylesterase homologs in C. elegans and other animals may reveal additional new compound families and signaling paradigms