Resonances in twisted quantum waveguides

In this paper we consider embedded eigenvalues of a Schroedinger Hamiltonian in a waveguide induced by a symmetric perturbation. It is shown that these eigenvalues become unstable and turn into resonances after twisting of the waveguide. The perturbative expansion of the resonance width is calculated for weakly twisted waveguides and the influence of the twist on resonances in a concrete model is discussed in detail.Comment: 15 Page

ν(νˉ)\nu(\bar\nu)-208^{208}Pb deep inelastic scattering

Nuclear-medium effects in the weak structure functions $F_2(x,Q^2)$ and $F_3(x,Q^2)$ in the charged current neutrino and antineutrino induced deep inelastic reactions in $^{208}$Pb have been studied. The calculations have been performed in a theoretical model using relativistic nuclear spectral functions which incorporate Fermi motion, binding and nucleon correlations. We also consider the pion and rho meson cloud contributions calculated from a microscopic model for meson-nucleus self-energies. Using these structure functions, the results for the differential cross section have been obtained and compared with the CERN Hybrid Oscillation Research apparatUS (CHORUS) data. The results for the ratios $\frac{2F_{i}^{Pb}}{208F_i^D}$, $\frac{4F_{i}^{Pb}}{208F_i^{He}}$, $\frac{12F_{i}^{Pb}}{208F_i^C}$, $\frac{16F_{i}^{Pb}}{208F_i^O}$, and $\frac{56F_{i}^{Pb}}{208F_i^{Fe}}$ (i=2,3) have also been obtained and a few have been compared with some of the phenomenological fits.Comment: 19Pages, 12 Fig

Endogenous pararetrovirus sequences associated with 24 nt small RNAs at the centromeres of Fritillaria imperialis L. (Liliaceae), a species with a giant genome

Funded by: Leonardo da Vinci programme, Marie Curie programme, Natural Environment Research Council. Grant Number: NE/G01724/1, Czech Science Foundation. Grant Number: P501/13/10057S

Zeolite-Stabilized Di- and Tetranuclear Molybdenum Sulfide Clusters Form Stable Catalytic Hydrogenation Sites

Supercages of faujasite (FAU)‐type zeolites serve as a robust scaffold for stabilizing dinuclear (Mo2S4) and tetranuclear (Mo4S4) molybdenum sulfide clusters. The FAU‐encaged Mo4S4 clusters have a distorted cubane structure similar to the FeMo‐cofactor in nitrogenase. Both clusters possess unpaired electrons on Mo atoms. Additionally, they show identical catalytic activity per sulfide cluster. Their catalytic activity is stable (> 150 h) for ethene hydrogenation, while layered MoS2 structures deactivate significantly under the same reaction conditions

Zeolite-Stabilized Di- and Tetranuclear Molybdenum Sulfide Clusters Form Stable Catalytic Hydrogenation Sites

Supercages of faujasite (FAU)‐type zeolites serve as a robust scaffold for stabilizing dinuclear (Mo2S4) and tetranuclear (Mo4S4) molybdenum sulfide clusters. The FAU‐encaged Mo4S4 clusters have a distorted cubane structure similar to the FeMo‐cofactor in nitrogenase. Both clusters possess unpaired electrons on Mo atoms. Additionally, they show identical catalytic activity per sulfide cluster. Their catalytic activity is stable (> 150 h) for ethene hydrogenation, while layered MoS2 structures deactivate significantly under the same reaction conditions

Astonishing 35S rDNA diversity in the gymnosperm species Cycas revoluta Thunb

17 p., tablas, gráficos.In all eukaryotes, the highly repeated 35S ribosomal DNA (rDNA) sequences encoding 18S-5.8S-26S ribosomal RNA (rRNA) typically show high levels of intragenomic uniformity due to homogenisation processes, leading to concerted evolution of 35S rDNA repeats. Here, we compared 35S rDNA divergence in several seed plants using next generation sequencing and a range of molecular and cytogenetic approaches. Most species showed similar 35S rDNA homogeneity indicating concerted evolution. However, Cycas revoluta exhibits an extraordinary diversity of rDNA repeats (nucleotide sequence divergence of different copies averaging 12 %), influencing both the coding and non-coding rDNA regions nearly equally. In contrast, its rRNA transcriptome was highly homogeneous suggesting that only a minority of genes ( T substitutions located in symmetrical CG and CHG contexts which were also highly methylated. Both functional genes and pseudogenes appear to cluster on chromosomes. The extraordinary high levels of 35S rDNA diversity in C. revoluta, and probably other species of cycads, indicate that the frequency of repeat homogenisation has been much lower in this lineage, compared with all other land plant lineages studied. This has led to the accumulation of methylation-driven mutations and pseudogenisation. Potentially, the reduced homology between paralogs prevented their elimination by homologous recombination, resulting in long-term retention of rDNA pseudogenes in the genome.The work was supported by the Czech Science Foundation (P501/13/10057S and P501/12/G090) and NERC (UK).Peer reviewe

Angiosperms Are Unique among Land Plant Lineages in the Occurrence of Key Genes in the RNA-Directed DNA Methylation (RdDM) Pathway

We are grateful for the FP7 Marie Curie IEF (Lu Ma), the FP7 Marie Curie ITN INTERCROSSING (Andrea Hatlen), the Czech Science Foundation (501/12/G090, Ales Kovarik), China Scholarship Council (Wencai Wang), and NERC (NE/ G01724/1, Laura Kelly, Ilia Leitch, Andrew Leitch). The Illumina sequencing of Fritillaria was funded by NERC (NE/G01724/1) and generated by the Centre of Genomic Research in the University of Liverpool, UK. This research utilised Queen Mary's MidPlus computational facilities, supported by QMUL Research-IT and funded by EPSRC grant EP/K000128/1. We thank an anonymous referee for a rigorous, insightful and helpful revie

Insects Inhabiting the Burrows of the Ozark Pocket Gopher in Arkansas

Pocket gopher burrows provide a stable environment for a variety of inquilines; hence this mammal is regarded as a keystone species. Most of the arthropods inhabiting pocket gopher burrows are restricted to this microhabitat. As part of a planned state-wide biotic survey of insects inhabiting this unusual microhabitat, we have focused our initial sampling efforts on the Ozark pocket gopher (Geomys bursarius ozarkensis; Geomyidae). In 2004 and 2005, pitfall traps were established in pocket gopher burrows and in 2007 and 2008, nests and associated chambers were excavated. Retrieved samples contained scarab, histerid, and rove beetles, cave crickets and anthomyiid flies. The histerids consisted of five species, one of which is undescribed, and all of which are new state records. A total of five species of scarab beetles were collected and all of these represent new state records. Two species of cave crickets were collected; one appears to be undescribed, and the other is essentially a Great Plains species and represents a considerable range extension. Both crickets are new to Arkansas

Eigenvalue Bounds for Perturbations of Schrodinger Operators and Jacobi Matrices With Regular Ground States

We prove general comparison theorems for eigenvalues of perturbed Schrodinger operators that allow proof of Lieb--Thirring bounds for suitable non-free Schrodinger operators and Jacobi matrices.Comment: 11 page