1,256 research outputs found
Induced Ge Spin Polarization at the Fe/Ge Interface
We report direct experimental evidence showing induced magnetic moments on Ge
at the interface in an Fe/Ge system. Details of the x-ray magnetic circular
dichroism and resonant magnetic scattering at the Ge L edge demonstrate the
presence of spin-polarized {\it s} states at the Fermi level, as well as {\it
d} character moments at higher energy, which are both oriented antiparallel to
the moment of the Fe layer. Use of the sum rules enables extraction of the L/S
ratio, which is zero for the {\it s} part and for the {\it d}
component. These results are consistent with layer-resolved electronic
structure calculations, which estimate the {\it s} and {\it d} components of
the Ge moment are anti-parallel to the Fe {\it 3d} moment and have a magnitude
of .Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let
Context dependent substitution biases vary within the human genome
Background:
Models of sequence evolution typically assume that different nucleotide positions evolve independently. This assumption is widely appreciated to be an over-simplification. The best known violations involve biases due to adjacent nucleotides. There have also been suggestions that biases exist at larger scales, however this possibility has not been systematically explored.
Results:
To address this we have developed a method which identifies over- and under-represented substitution patterns and assesses their overall impact on the evolution of genome composition. Our method is designed to account for biases at smaller pattern sizes, removing their effects. We used this method to investigate context bias in the human lineage after the divergence from chimpanzee. We examined bias effects in substitution patterns between 2 and 5 bp long and found significant effects at all sizes. This included some individual three and four base pair patterns with relatively large biases. We also found that bias effects vary across the genome, differing between transposons and non-transposons, between different classes of transposons, and also near and far from genes.
Conclusions:
We found that nucleotides beyond the immediately adjacent one are responsible for substantial context effects, and that these biases vary across the genome
Quantifying the Importance of Ram Pressure Stripping in a Galaxy Group at 100 Mpc
We examine two members of the NGC 4065 group of galaxies: a bent-double
(a.k.a. wide angle tail) radio source and an HI deficient spiral galaxy. Models
of the X-ray emitting intragroup gas and the bent-double radio source, NGC
4061, are used to probe the density of intergalactic gas in this group. HI
observations reveal an asymmetric, truncated distribution of neutral gas in
spiral galaxy, UGC 07049, and the accompanying radio continuum emission reveals
strong star formation. We examine the effectiveness of ram pressure stripping
as a gas removal mechanism and find that it alone cannot account for the HI
deficiency that is observed in UGC 07049 unless this galaxy has passed through
the core of the group with a velocity of ~800 km/s. A combination of tidal and
ram pressure stripping are necessary to produce the HI deficiency and asymmetry
in this galaxy.Comment: 8 pages, 6 figures, MNRAS accepte
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