22,565 research outputs found
Assembly of RNPs: help needed
This extract was created in the absence of an abstract: In 1968 the Nomura lab in Madison made an astonishing observation: when ribosomal proteins were mixed under appropriate conditions with 16S rRNA, fully functional ribosomal 30S subunits were formed. Along with the subsequent total reconstitution of 50S subunits, it was established that even entire ribosomes could be assembled in vitro from their constituents. Neither energy in the form of nucleoside triphosphates, nor other âhelping factors,â were required for this reaction. It was thus concluded that the structural information required for the formation of even complex macromolecules lies within its individual components itself and hence allows âself assembly.â This notion was soon supported by many other labs, which managed to assemble macromolecular RNPs in spontaneous reactions, including the signal recognition particle (SRP), spliceosomal subcomplexes (U snRNPs) and nucleolar RNPs (snoRNPs), to name just a few. These findings were in full accordance with the observations of the Anfinsen lab in the 1950s
Optimization of nanostructured permalloy electrodes for a lateral hybrid spin-valve structure
Ferromagnetic electrodes of a lateral semiconductor-based spin-valve
structure are designed to provide a maximum of spin-polarized injection
current. A single-domain state in remanence is a prerequisite obtained by
nanostructuring Permalloy thin film electrodes. Three regimes of aspect ratios
are identified by room temperature magnetic force microscopy: (i)
high-aspect ratios of provide the favored remanent single-domain
magnetization states, (ii) medium-aspect ratios to yield
highly remanent states with closure domains and (iii) low-aspect ratios of lead to multi-domain structures. Lateral kinks, introduced to bridge the
gap between micro- and macroscale, disturb the uniform magnetization of
electrodes with high- and medium-aspect ratios. However, vertical flanks help
to maintain a uniformly magnetized state at the ferromagnet-semiconcuctor
contact by domain wall pinning.Comment: revised version, major structural changes, figures reorganized,6
pages, 8 figures, revte
NÀhrstoffsalden und Nitratgehalte des Sickerwassers in ökologisch und konventionell bewirtschafteter AckerflÀchen
Die NĂ€hrstoffsalden ökologisch bewirtschafteter Betriebe lagen bei den HauptnĂ€hrstoffen Stickstoff, Phosphat und Kali deutlich unter den Salden konventionell bewirtschafteter Betriebe. Bei Phosphat und Kali wurden negative Salden festgestellt. Bei mittel- und langfristiger Betrachtung werden die pflanzenverfĂŒgbaren Bodengehalte sinken. Unter 10 mg/100 g Boden muss im Rahmen der zugelassenen Möglichkeiten eine ErhaltungsdĂŒngung durchgefĂŒhrt werden, wenn das mögliche Ertragspotential ausgeschöpft werden soll. Die dargestellten Unterschiede der Stickstoffsalden bei konventioneller und ökologischer Bewirtschaftung werden durch Untersuchungsergebnisse hinsichtlich der Nitratkonzentration im Sickerwasser bestĂ€tigt. Nach unseren Untersuchungen lag die Nitratkonzentration unterhalb des durchwurzelbaren Raumes unter ökologisch bewirtschafteten FlĂ€chen deutlich unter den Gehalten konventionell bewirtschafteter FlĂ€chen. Sie lagen aber im Mittel ĂŒber dem Richtwert fĂŒr Trinkwasser von 25mg/l
Analysis of induced gamma activation by D-T neutrons in selected fusion reactor relevant materials with EAF-2010
Samples of lanthanum, erbium and titanium which are constituents of structural materials, insulating coatings and tritium breeder for blankets of fusion reactor designs have been irradiated in a fusion peak neutron field. The induced gamma activities were measured and the results were used to check calculations with the European activation system EASY-2010. Good agreement for the prediction of major contributors to the contact dose rate of the materials was found, but for minor contributors the calculation deviated up to 50%
Condensate fragmentation as a sensitive measure of the quantum many-body behavior of bosons with long-range interactions
The occupation of more than one single-particle state and hence the emergence
of fragmentation is a many-body phenomenon universal to systems of spatially
confined interacting bosons. In the present study, we investigate the effect of
the range of the interparticle interactions on the fragmentation degree of one-
and two-dimensional systems. We solve the full many-body Schr\"odinger equation
of the system using the recursive implementation of the multiconfigurational
time-dependent Hartree for bosons method, R-MCTDHB. The dependence of the
degree of fragmentation on dimensionality, particle number, areal or line
density and interaction strength is assessed. It is found that for contact
interactions, the fragmentation is essentially density independent in two
dimensions. However, fragmentation increasingly depends on density the more
long-ranged the interactions become. The degree of fragmentation is increasing,
keeping the particle number fixed, when the density is decreasing as
expected in one spatial dimension. We demonstrate that this remains,
nontrivially, true also for long-range interactions in two spatial dimensions.
We, finally, find that within our fully self-consistent approach, the
fragmentation degree, to a good approximation, decreases universally as
when only is varied.Comment: 8 pages of RevTex4-1, 5 figure
- âŠ