Generalized diagonal crossed products and smash products for quasi-Hopf algebras. Applications

In this paper we introduce generalizations of diagonal crossed products, two-sided crossed products and two-sided smash products, for a quasi-Hopf algebra H. The results we obtain may be applied to H^*-Hopf bimodules and generalized Yetter-Drinfeld modules. The generality of our situation entails that the "generating matrix" formalism cannot be used, forcing us to use a different approach. This pays off because as an application we obtain an easy conceptual proof of an important but very technical result of Hausser and Nill concerning iterated two-sided crossed products.Comment: 41 pages, no figure

Do riverine barriers, history or introgression shape the genetic structuring of a common shrew (Sorex araneus) population?

The common shrew (Sorex araneus) is subdivided into numerous chromosome races. The Valais and Cordon chromosome races meet and hybridize at a mountain river in Les Houches (French Alps). Significant genetic structuring was recently reported among populations found on the Valais side of this hybrid zone. In this paper, a phylogenetic analysis and partial Mantel tests are used to investigate the patterns and causes of this structuring. A total of 185 shrews were trapped at 12 localities. All individuals were typed for nine microsatellite loci. Although several mountain rivers are found in the study area, riverine barriers do not have a significant influence on gene flow. Partial Mantel tests show that our result is caused by the influence of the hybrid zone with the Cordon race. The geographical patterns of this structuring are discussed in the context of the contact zone, which appears to extend up to a group of two rivers. The glacier they originate from is known to have cut the Arve valley as recently as 1818. The recent history of this glacier, its moraine and possibly rivers, may therefore be linked to the history of this hybrid zone

Dynamic nuclear polarisation in p-doped silicon by microwave ultrasonics

We have investigated the dynamic nuclear polarisation (DNP) of 29 Si nuclei in highly doped silicon single crystals. The saturation of the electronic Zeeman levels in a magnetic field of 3.3 kG at 1.6°K was obtained using microwave ultrasonics of about 9 GHz. The ultrasonic waves were generated in a cavity by means of a transducer consisting of a thin film of CdS evaporated on the polished surface of the silicon. Preliminary results obtained with a silicon-rod of 2 x 2 x 12 mm cut with the long axis parallel to the (110) direction rendered a reduction of the NMR signal to about ⅓ in agreement with the expected negative sign of the DNP

Accuracy of B(E2; 0+ -> 2+) transition rates from intermediate-energy Coulomb excitation experiments

The method of intermediate-energy Coulomb excitation has been widely used to determine absolute B(E2; 0+ -> 2+) quadrupole excitation strengths in exotic nuclei with even numbers of protons and neutrons. Transition rates measured with intermediate-energy Coulomb excitation are compared to their respective adopted values and for the example of 26Mg to the B(E2; 0+ -> 2+) values obtained with a variety of standard methods. Intermediate-energy Coulomb excitation is found to have an accuracy comparable to those of long-established experimental techniques.Comment: to be published in Phys. Rev.

Transanular interaction in [2.2]phanes: [2.2](4,4')diphenylophane and [2.2](2,7) fluorenophane

The emission spectra and the zero field splitting parameters D and E of the first excited triplet states of [2.2](4,4′) diphenylophane 3 and of the two stereoisomeric syn- and anti [2.2] (2,7) fluorenophanes 4a and 4b are investigated and compared with those of the corresponding monomers

Transanular interactions in [2.2]phanes-relation between spectroscopic properties and structural parameters of [2.2]phanes

In this paper we attempt to explain the spectroscopic properties of a number of [2.2]phanes. All phanes discussed have in common that their two subunit

Photophysics of the electronic states S0 and S1 for the coplanar molecular structures of the α,ω-diphenylpolyenes DPH and DPO

Spectroscopy of the monoclinic and orthorhombic crystalline forms of all-trans-diphenylhexatriene (DPH) and all-trans-diphenyloctatetraene (DPO) show absorption and emission bands that do not generate the widely known Stokes shift of the polyene compounds, discovered by Hausser et al. in 1953 and repeatedly studied over the last 60 years. It can be concluded from our study that the crystallization system, whether in a monoclinic or orthorhombic system, does not significantly influence the photophysics of DPH and DPO in the crystal phas

Transanular interaction in [2.2]phanes: [2.2](2,7)pyrenophane

The emission spectra of [2.2](2,7)pyrenophane and the zero field splitting parameters D and E of its excited triplet state were measured in glasses and in small single crystals at 1.3 K. The results are being compared with monomer pyrene and 2,7 dimethylpyrene in liquid and solid solutions as well as in single crystals