Time variability of accretion flows: effects of the adiabatic index and gas temperature

We report on next phase of our study of rotating accretion flows onto black holes. We consider hydrodynamical (HD) accretion flows with a spherically symmetric density distribution at the outer boundary but with spherical symmetry broken by the introduction of a small, latitude-dependent angular momentum. We study accretion flows by means of numerical two-dimensional, axisymmetric, HD simulations for variety of the adiabatic index, $\gamma$ and the gas temperature at infinity, $c_\infty$. Our work is an extension of work done by Proga & Begelman who consider models for only $\gamma=5/3$. Our main result is that the flow properties such as the topology of the sonic surface and time behavior strongly depend on $\gamma$ but little on $c_\infty$. In particular, for $1 < \gamma < 5/3$, the mass accretion rate shows large amplitude, slow time-variability which is a result of mixing between slow and fast rotating gas. This temporal behavior differs significantly from that in models with \gamma\simless 5/3 where the accretion rate is relatively constant and from that in models with \gamma\simgreat 1 where the accretion exhibits small amplitude quasi-periodic oscillations. The key parameter responsible for the differences is the sound speed of the accretion flow which in turn determines whether the flow is dominated by gas pressure, radiation pressure or rotation. Despite these differences the time-averaged mass accretion rate in units of the corresponding Bondi rate is a weak function of $\gamma$ and $c_\infty$.Comment: 31 pages, 14 figures, accepted for publication in ApJ, for full resolution version goto http://users.camk.edu.pl/mmosc/ms.pd

Structure, Construction, and Emplacement of the Late Cretaceous Sonora Pass Intrusive Suite: Central Sierra Nevada Batholith, California

The \u3e1000 km2, ~95-88 Ma Sonora Pass intrusive suite is the oldest and most northern of the four voluminous, normally-zoned Late Cretaceous suites of the Sierra Nevada batholith. It consists of the older, marginal, equigranular Kinney Lakes hornblende-biotite granodiorite and the inner, porphyritic to megacrystic Topaz Lake biotite granodiorite. The suite intruded the ~109 Ma Bummers Flat biotite granodiorite, Jurassic diorites, and Pre-Cambrian to Cambrian metasedimentary rocks of the Snow Lake pendant. The Topaz Lake granodiorite records evidence of the development of a sizable magma chamber. The Bummers Flat and Kinney Lakes granodiorites were likely constructed by many increments, were capable of flow and disaggregation of host and co-magmatic mafic rocks, are marked by widespread schlieren, and may have not formed a single magma chamber. Accommodation of magmas was facilitated by multiple material transfer processes; stoping was the best documented process, followed by minor ductile flow and magmatic wedging of the Kinney Lakes granodiorite. There is no direct evidence for transfer processes during emplacement of the Topaz Lake granodiorite. Magmatic foliation within the study area records regional tectonic strain and complex internal magmatic processes. Solid-state structures including steep ductile shear zones, foliations, and lineations occur within the Bummers Flat granodiorite. One of these structures, the Toe Jam Lake shear zone, may extend for 10s of km, likely formed during ENE-WSW shortening, and probably predated the Sonora Pass intrusive suite

“Happily Ever After” for the Twenty-First Century? Sex, Love, and Human Identity in C. S. Lewis’ The Chronicles of Narnia

For better and for worse, classic fairy tales have come under severe criticism as paradigms of sexist patriarchy in recent decades. Likewise, C. S. Lewis has been viewed as sexist, even misogynistic. While many fairy tale and Lewis fans might be tempted to dismiss all of these criticisms as nonsense, gender is one of the predominant discourses of our time, our questions and the varied answers are significant, and in this essay I consider how Lewis’ development of the fairy tale genre in The Chronicles of Narnia offers timeless, possibly even surprising, Christian wisdom. How does Lewis portray sex, love, and human identity in these children’s novels? How does he deal with the related “happily ever after” concept? Are his representations of fairy tale motifs in sync with the genre, or do his novels suggest a significant departure? When might Lewis even be in agreement with feminist critics of classic fairy tales? Which aspects of cultural heritage does he affirm and which does he reject? With the sixtieth anniversary of the 1956 publication of The Last Battle, we have another opportunity to reconsider these important questions for the twenty-first century

Glucocorticoids for human skin: New aspects of the mechanism of action

Topical glucocorticoids have always been considered first-line drugs for inflammatory diseases of the skin and bronchial system. Applied systemically, glucocorticoids are used for severe inflammatory and immunological diseases and the inhibition of transplant rejection. Owing to the progress in molecular pharmacology, the knowledge of the mechanism of action has increased during the last years. Besides distinct genomic targets, which are due to the activation of specific cytoplasmatic receptors resulting in the (trans-) activation or (trans-) repression of target genes, there are non-genomic effects on the basis of the interference with membrane-associated receptors as well as with membrane lipids. In fact, various glucocorticoids appear to differ with respect to the relative influence on these targets. Thus, the extended knowledge of glucocorticoid-induced cellular signalling should allow the design and development of even more specifically acting drugs-as it has been obtained with other steroids, e.g. estrogens for osteoporosis prevention. Copyright (C) 2005 S. Karger AG, Basel