292 research outputs found
Neutrino signature of supernova hydrodynamical instabilities in three dimensions
The first full-scale three-dimensional (3D) core-collapse supernova (SN)
simulations with sophisticated neutrino transport show pronounced effects of
the standing accretion shock instability (SASI) for two high-mass progenitors
(20 and 27 M_sun). In a low-mass progenitor (11.2 M_sun), large-scale
convection is the dominant nonradial hydrodynamic instability in the postshock
accretion layer. The SASI-associated modulation of the neutrino signal (80 Hz
in our two examples) will be clearly detectable in IceCube or the future
Hyper-Kamiokande detector, depending on progenitor properties, distance, and
observer location relative to the main SASI sloshing direction. The neutrino
signal from the next galactic SN can therefore diagnose the nature of the
hydrodynamic instability.Comment: 6 pages, including 4 figures. Results unchanged. Matches published
version in PRL. Animated visualization available at:
http://www.mpa-garching.mpg.de/ccsnarchive/data/Hanke2013_movie/index.htm
Self-sustained asymmetry of lepton-number emission: A new phenomenon during the supernova shock-accretion phase in three dimensions
During the stalled-shock phase of our 3D hydrodynamical core-collapse
simulations with energy-dependent, 3-flavor neutrino transport, the
lepton-number flux (nue minus antinue) emerges predominantly in one hemisphere.
This novel, spherical-symmetry breaking neutrino-hydrodynamical instability is
termed LESA for "Lepton-number Emission Self-sustained Asymmetry." While the
individual nue and antinue fluxes show a pronounced dipole pattern, the
heavy-flavor neutrino fluxes and the overall luminosity are almost spherically
symmetric. Initially, LESA seems to develop stochastically from convective
fluctuations, it exists for hundreds of milliseconds or more, and it persists
during violent shock sloshing associated with the standing accretion shock
instability. The nue minus antinue flux asymmetry originates mainly below the
neutrinosphere in a region of pronounced proto-neutron star (PNS) convection,
which is stronger in the hemisphere of enhanced lepton-number flux. On this
side of the PNS, the mass-accretion rate of lepton-rich matter is larger,
amplifying the lepton-emission asymmetry, because the spherical stellar infall
deflects on a dipolar deformation of the stalled shock. The increased shock
radius in the hemisphere of less mass accretion and minimal lepton-number flux
(antinue flux maximum) is sustained by stronger convection on this side, which
is boosted by stronger neutrino heating because the average antinue energy is
higher than the average nue energy. Asymmetric heating thus supports the global
deformation despite extremely nonstationary convective overturn behind the
shock. While these different elements of LESA form a consistent picture, a full
understanding remains elusive at present. There may be important implications
for neutrino-flavor oscillations, the neutron-to-proton ratio in the
neutrino-heated supernova ejecta, and neutron-star kicks, which remain to be
explored.Comment: 21 pages, 15 figures; new results and new figure added; accepted by
Ap
A comprehensive evaluation of rhythm monitoring strategies for the detection of atrial fibrillation recurrence: insights from 647 continuously monitored patients and implications for monitoring after therapeutic interventions
No description supplie
Eigenheime - bewohnte Bollwerke für Demokratie : schweizer Pestalozzi-Dörfer für Berglehrlinge und amerikanische MSA-Bergarbeitersiedlungen als Beispiele für die Neuordnung der westdeutschen Wohnkultur
Wissenschaftliches Kolloquium vom 18. bis 21. Juni 1992 in Weimar an der Hochschule für Architektur und Bauwesen zum Thema: ‚Architektur und Macht
Accumulation and nuclear import of HIF1 alpha during high and low oxygen concentration in skeletal muscle cells in primary culture
AbstractThe hypoxia-inducible-factor-1 (HIF1) mediates the transcriptional upregulation of several target genes during hypoxia. HIF1 itself is known to be regulated essentially by ubiquitinylation and proteolytic degradation of the subunit HIF1α of the dimeric transcription factor HIF1. In contrast to other tissues, skeletal muscle expresses high amounts of HIF1α in normoxia as well as in hypoxia. In view of this, we aimed to investigate HIF1α accumulation and subcellular localization as well as the transcriptional activity of the HIF1α-regulated gene of glyceraldehyde dehydrogenase (GAPDH) in skeletal muscle cells exposed to low oxygen concentration (3% O2), normoxia (20% O2) or high oxygen concentration (42% O2). Immunofluorescence analysis reveals that under normoxic and high oxygen conditions, significant amounts of HIF1α can be found exclusively in the cytoplasm of the myotubes. Muscle cells treated with CoCl2, a known inhibitor of HIF1α degradation, show even higher levels of HIF1α, again exclusively in the cytoplasm. Under conditions of low oxygen, HIF1α in controls as well as in CoCl2-treated cells is found in the nuclei. CdCl2 inhibits nuclear import of HIF1α at low oxygen concentration and leads to a transcriptional downregulation of the marker enzyme of anaerobic glycolysis GAPDH. Immunoprecipitation with anti-HIF1α antibody co-precipitates HSP90 in an oxygen-dependent manner, more at high pO2 than at low pO2. Cadmium-treated samples also show high amounts of co-immunoprecipitated HSP90, independent of oxygen concentration. We conclude that in skeletal muscle cells, HIF1α, in contrast to other tissues, may, in addition to its regulation by degradation, also be regulated by binding to HSP90 and subsequent inhibition of its import into the nuclei
Traditionelle Boote in Deutschland. T. 2, Die mittelrheinische Lotsenschaluppe
"Of the many Rhine boat types, the pilot shallop oft he Middle Rhine plays a special role as the vessel used by pilots on the section of the river between Bingen and St. Goar. In 1980, within the framework of the project 'Pre-industrial watercraft in the Rhine river basin' carried out by the German Society for the Advancement of Scientific Research, the last wooden example of this vessel type, in use until the 1960s, was measured at the Rheinfels Castle near St. Goar. This article documents a riveted clinker boat of 4.65 metres in length, comparable in type to the 'norsk pram.'" (author's abstract
Traditionelle Boote in Deutschland. T. 5, Der Fischerschelch am Obermain
"Even today, the fisherman's barge is the type of vessel most commonly used for fishing on the River Main and its tributaries upstream beyond the city of Würzburg. Like the similar fishing barge of the Middle Main (see Deutsches Schiffahrtsarchiv 18/1995) the oaken boat is a flat-bottomed vessel whose ends taper to a narrow width at bow and stern. The sides consists of one plank each. The wooden fisherman's barges of the Upper Main were documented in 1980-81 within the framework of a research project. Present-day vessels were found to have an average length of ca. 8.1 m, while there is clear evidence that they were at least 1 m Ionger in earlier times. Their width is greatest between the forward third and the middle, where it measures 1.5 m on average. With a length-width ratio of 7:1, the present vessels are narrower than their older Counterparts, which exhibited a length-width ratio of 6:1. The two boat ends curve upward by about 0.5 m over a length of ca. 1.9 m. The boat is paddled and poled; in former times it was towed upstream. As a rule the fishermen of the present use outboard motors for propulsion. With regard to the arrangement of the ribs in the middle section between the upwardly curving ends, the fisherman's barge of the Upper Main differs from that of the Middle Main. At regular intervals of 0.9-1.0 m several rib pairs have been installed. The vessel has no built-in fish box but tows a floating box in which to store the fish live during the haul. During the 1980s wooden fisherman's barges were still being built on the Upper Main by a boatbuilder in Knetzgau near Bamberg. At that time he was the last boatbuilder in the entire Rhine basin still producing oaken boats. Since the 1960s he had been practising this trade as a sideline in an open-air boatyard behind his home. A record of orders received provided evidence of the boats supplied by this boatyard as well as their distribution area, which expanded spatially in the course of the years." (author's abstract
Traditionelle Boote in Deutschland. T. 1, Die Ruhrfähre von Oefte
"In 1979, as part of the research project 'Pre-industrial watercraft in the Rhine river basin' the Ruhr ferry of Oefte was measured and documented. At that time this vessel was the last surviving example of the once large number of local passenger ferries on the Ruhr. It was not until the twentieth century that ferrying facilities such as this one were rendered unprofitable and superfluous by the construction of bridges. Only once - following the Second World War, when numerous bridges had been destroyed - did the ferries experience a temporary revival before disappearing from the scene altogether. Operation of the Oefte ferry was discontinued in 1980 when the vessel was deemed unsafe and the acquisition of a new boat would have been too great an expense for the owner. Until its lay-up the ferry of Oefte had been used by schools to demonstrate historic means of transportation and by strollers. Like its predecessor, the wooden ferryboat was built in the boatyard of Dorsten on basin. More specifically, it is to be classified as a Nachen of the Lower Rhine. The Nachen is a flat-bottomed vessel whose side planks are joined by a special method of nailing. Because of its utilization as a ferry the two ends of this particular boat differ from the typical Nachen form: the bow and the stern are wider than usual. The building material used was oak. The Oefte ferry was operated by rowing. The boat's equipment consisted of four oars (two of them carried as spares), a boathook, a wooden bailer and a life buoy with a throwing line. Aside from the boat itself the facility included a landing stage, a ferry bell and a shed serving the passengers as a shelter." (author's abstract
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