32,340 research outputs found
Coulomb force effects in low-energy -deuteron scattering
The -proton Coulomb interaction is included in the description of
-deuteron scattering using the screening and renormalization approach
in the framework of momentum-space three-particle equations. The technical
reliability of the method is demonstrated. Large Coulomb-force effects are
found.Comment: To be published in Phys. Rev.
Some Aspects of the Exact Foldy-Wouthuysen Transformation for a Dirac Fermion
The Foldy-Wouthuysen transformation (FWT) is used to separate distinct
components of relativistic spinor field, e.g. electron and positron. Usually,
the FWT is perturbative, but in some cases there is an involution operator and
the transformation can be done exactly. We consider some aspects of an exact
FWT and show that, even if the theory does not admit an involution operator,
one can use the technique of exact FWT to obtain the conventional perturbative
result. Several particular cases can be elaborated as examples
Topological Hall effect and Berry phase in magnetic nanostructures
We discuss the anomalous Hall effect in a two-dimensional electron gas
subject to a spatially varying magnetization. This topological Hall effect
(THE) does not require any spin-orbit coupling, and arises solely from Berry
phase acquired by an electron moving in a smoothly varying magnetization. We
propose an experiment with a structure containing 2D electrons or holes of
diluted magnetic semiconductor subject to the stray field of a lattice of
magnetic nanocylinders. The striking behavior predicted for such a system (of
which all relevant parameters are well known) allows to observe unambiguously
the THE and to distinguish it from other mechanisms.Comment: 5 pages with 4 figure
Theory of interlayer exchange interactions in magnetic multilayers
This paper presents a review of the phenomenon of interlayer exchange
coupling in magnetic multilayers. The emphasis is put on a pedagogical
presentation of the mechanism of the phenomenon, which has been successfully
explained in terms of a spin-dependent quantum confinement effect. The
theoretical predictions are discussed in connection with corresponding
experimental investigations.Comment: 18 pages, 4 PS figures, LaTeX with IOP package; v2: ref. added.
Further (p)reprints available from http://www.mpi-halle.de/~theory
Anopheline salivary protein genes and gene families: an evolutionary overview after the whole genome sequence of sixteen Anopheles species
Background: Mosquito saliva is a complex cocktail whose pharmacological properties play an essential role in
blood feeding by counteracting host physiological response to tissue injury. Moreover, vector borne pathogens are
transmitted to vertebrates and exposed to their immune system in the context of mosquito saliva which, in virtue
of its immunomodulatory properties, can modify the local environment at the feeding site and eventually affect
pathogen transmission. In addition, the host antibody response to salivary proteins may be used to assess human
exposure to mosquito vectors. Even though the role of quite a few mosquito salivary proteins has been clarified in
the last decade, we still completely ignore the physiological role of many of them as well as the extent of their
involvement in the complex interactions taking place between the mosquito vectors, the pathogens they transmit
and the vertebrate host. The recent release of the genomes of 16 Anopheles species offered the opportunity to get
insights into function and evolution of salivary protein families in anopheline mosquitoes.
Results: Orthologues of fifty three Anopheles gambiae salivary proteins were retrieved and annotated from 18
additional anopheline species belonging to the three subgenera Cellia, Anopheles, and Nyssorhynchus. Our analysis
included 824 full-length salivary proteins from 24 different families and allowed the identification of 79 novel
salivary genes and re-annotation of 379 wrong predictions. The comparative, structural and phylogenetic analyses
yielded an unprecedented view of the anopheline salivary repertoires and of their evolution over 100 million years
of anopheline radiation shedding light on mechanisms and evolutionary forces that contributed shaping the
anopheline sialomes.
Conclusions: We provide here a comprehensive description, classification and evolutionary overview of the main
anopheline salivary protein families and identify two novel candidate markers of human exposure to malaria vectors
worldwide. This anopheline sialome catalogue, which is easily accessible as hyperlinked spreadsheet, is expected to
be useful to the vector biology community and to improve the capacity to gain a deeper understanding of
mosquito salivary proteins facilitating their possible exploitation for epidemiological and/or pathogen-vector-host
interaction studies
Electron paramagnetic resonance studies of slowly tumbling vanadyl spin probes in nematic liquid crystals
An analysis of EPR line shapes by the method of Polnaszek, Bruno, and Freed is made for slowly tumbling vanadyl spin probes in viscous nematic liquid crystals. The use of typical vanadyl complexes as spin probes for nematic liquid crystals is shown to simplify the theoretical analysis and the subsequent interpretation. Rotational correlation times tau and orientational ordering parameters S sub Z where slow tumbling effects are expected to be observed in vanadyl EPR spectra are indicated in a plot. Analysis of the inertial effects on the probe reorientation, which are induced by slowly fluctuating torque components of the local solvent structure, yield quantitative values for tau and S sub Z. The weakly ordered probe VOAA is in the slow tumbling region and displays these inertial effects throughout the nematic range of BEPC and Phase V. VOAA exhibits different reorientation behavior near the isotropic-nematic transition temperature than that displayed far below this transition temperature
ESR studies of the slow tumbling of vanadyl spin probes in nematic liquid crystals
ESR line shapes that are appropriate for slowly tumbling vanadyl spin probes in viscous nematic liquid crystals were calculated by the stochastic Liouville method. Because of the symmetry possessed by vanadyl, the analysis and interpretation of these line shapes was simplified considerably. Spectral line shapes agreed well with experimental spectra of VOAcAc in the nematic liquid crystal Phase V and BEPC. Deviations from Brownian rotational diffusion were noted. A slowly fluctuating torque analysis yielded good agreement with the experimental spectra
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