Spin-dependent transmission through a chain of rings: influence of a periodically modulated spin-orbit interaction strength or ring radius

We study ballistic electron transport through a finite chain of quantum circular rings in the presence of spin-orbit interaction of strength \alpha. For a single ring the transmission and reflection coefficients are obtained analytically and from them the conductance for a chain of rings as a function of \alpha and of the wave vector k of the incident electron. We show that due to destructive spin interferences the chain can be totaly opaque for certain ranges of k the width of which depends on the value of \alpha. A periodic modulation of the strength \alpha or of the ring radius widens up the gaps considerably and produces a nearly binary conductance output.Comment: 4 pages, 4 figures. Appl. Phys. Lett., in pres

Cytomolecular identification of individual wheat-wheat chromosome arm associations in wheat-rye hybrids

Chromosome pairing in the meiotic metaphase I of wheatrye hybrids has been characterized by sequential genomic and fluorescent in situ hybridization allowing not only the discrimination of wheat and rye chromosomes, but also the identification of the individual wheat and rye chromosome arms involved in the chromosome associations. The majority of associations (93.8%) were observed between the wheat chromosomes. The largest number of wheat-wheat chromosome associations (53%) was detected between the A and D genomes, while the frequency of B-D and A-B associations was significantly lower (32 and 8%, respectively). Among the A-D chromosome associations, pairing between the 3AL and 3DL arms was observed with the highest frequency, while the most frequent of all the chromosome associations (0.113/ cell) was found to be the 3DS-3BS. Differences in the pairing frequency of the individual chromosome arms of wheat-rye hybrids have been discussed in relation to the homoeologous relationships between the constituent genomes of hexaploid wheat

Maps on density operators preserving quantum f-divergences

For an arbitrary strictly convex function f defined on the non-negative real line we determine the structure of all transformations on the set of density operators which preserve the quantum f-divergence

Changes in the hardwood groves of the Martonvásár Manor Park (Hungary) in the last 30 years

The subject of the present study is the monitoring of the hardwood groves at the Martonvásár Manor Park with the involvement of 20 earlier (recorded in 1980–1981) and 20 current (recorded in 2011–2012) phytocoenological relevés. The manor park was created in the first half of the 19th century. Since then the woods along the St László stream have developed into species-rich and semi-natural forests, which can be identified as related to the oak-ash-elm groves (Scillo vindobonensis-Ulmetum) of the Zámoly Basin and the Csepel Island. The results of the current monitoring repeated 30 years after the first survey show momentous changes in forest dynamics such as the ageing-related opening of the upper canopy and an intense closure of the lower canopy and shrub layer. The ratio of the invasive species doubled. Present findings may provide additional information for long-term forest ecology research, however, results could be considered as changes of a semi-natural hardwood forest with minimal human impact