82 research outputs found
Andreev scattering in nanoscopic junctions at high magnetic fields
We report on the measurement of multiple Andreev resonances at atomic size
point contacts between two superconducting nanostructures of Pb under magnetic
fields higher than the bulk critical field, where superconductivity is
restricted to a mesoscopic region near the contact. The small number of
conduction channels in this type of contacts permits a quantitative comparison
with theory through the whole field range. We discuss in detail the physical
properties of our structure, in which the normal bulk electrodes induce a
proximity effect into the mesoscopic superconducting part.Comment: 4 page
Stability of the vortex lattice in D-wave superconductors
Use is made of Onsager's hydrodynamic equation to derive the vibration
spectrum of the vortex lattice in d-wave superconductor. In particular the
rhombic lattice (i.e. the tilted square lattice) is found to be
stable for . Here denotes the critical field at which
the vortex lattice transition takes place.Comment: 7 pages, Revte
Josephson effect in a weak link between borocarbides
A stationary Josephson effect is analyzed theoretically for a weak link
between borocarbide superconductors. It is shown that different models of the
order parameter result in qualitatively different current-phase relations
Flavour Symmetries and Kahler Operators
Any supersymmetric mechanism to solve the flavour puzzle would generate
mixing both in the superpotential Yukawa couplings and in the Kahler potential.
In this paper we study, in a model independent way, the impact of the
nontrivial structure of the Kahler potential on the physical mixing matrix,
after kinetic terms are canonically normalized. We undertake this analysis both
for the quark sector and the neutrino sector. For the quark sector, and in view
of the experimental values for the masses and mixing angles, we find that the
effects of canonical normalization are subdominant. On the other hand, for the
leptonic sector we obtain different conclusions depending on the spectrum of
neutrinos. In the hierarchical case we obtain similar conclusion as in the
quark sector, whereas in the degenerate and inversely hierarchical case,
important changes in the mixing angles could be expected.Comment: 22 pages, LaTe
Outer Membrane Vesicles as a Candidate Vaccine against Edwardsiellosis
Infection with Edwardsiella tarda, a Gram-negative bacterium, causes high morbidity and mortality in both marine and freshwater fish. Outer membrane vesicles (OMVs) released from Gram-negative bacteria are known to play important roles in bacterial pathogenesis and host immune responses, but no such roles for E. tarda OMVs have yet been described. In the present study, we investigated the proteomic composition of OMVs and the immunostimulatory effect of OMVs in a natural host, as well as the efficacy of OMVs when used as a vaccine against E. tarda infection. A total of 74 proteins, from diverse subcellular fractions, were identified in OMVs. These included a variety of important virulence factors, such as hemolysin, OmpA, porin, GAPDH, EseB, EseC, EseD, EvpC, EvpP, lipoprotein, flagellin, and fimbrial protein. When OMVs were administrated to olive flounder, significant induction of mRNAs encoding IL-1β, IL-6, TNFα, and IFNγ was observed, compared with the levels seen in fish injected with formalin-killed E. tarda. In a vaccine trial, olive flounder given OMVs were more effectively protected (p<0.0001) than were control fish. Investigation of OMVs may be useful not only for understanding the pathogenesis of E. tarda but also in development of an effective vaccine against edwardsiellosis
Systematic and Evolutionary Insights Derived from mtDNA COI Barcode Diversity in the Decapoda (Crustacea: Malacostraca)
Background: Decapods are the most recognizable of all crustaceans and comprise a dominant group of benthic invertebrates of the continental shelf and slope, including many species of economic importance. Of the 17635 morphologically described Decapoda species, only 5.4% are represented by COI barcode region sequences. It therefore remains a challenge to compile regional databases that identify and analyse the extent and patterns of decapod diversity throughout the world. Methodology/Principal Findings: We contributed 101 decapod species from the North East Atlantic, the Gulf of Cadiz and the Mediterranean Sea, of which 81 species represent novel COI records. Within the newly-generated dataset, 3.6% of the species barcodes conflicted with the assigned morphological taxonomic identification, highlighting both the apparent taxonomic ambiguity among certain groups, and the need for an accelerated and independent taxonomic approach. Using the combined COI barcode projects from the Barcode of Life Database, we provide the most comprehensive COI data set so far examined for the Order (1572 sequences of 528 species, 213 genera, and 67 families). Patterns within families show a general predicted molecular hierarchy, but the scale of divergence at each taxonomic level appears to vary extensively between families. The range values of mean K2P distance observed were: within species 0.285% to 1.375%, within genus 6.376% to 20.924% and within family 11.392% to 25.617%. Nucleotide composition varied greatly across decapods, ranging from 30.8 % to 49.4 % GC content. Conclusions/Significance: Decapod biological diversity was quantified by identifying putative cryptic species allowing a rapid assessment of taxon diversity in groups that have until now received limited morphological and systematic examination. We highlight taxonomic groups or species with unusual nucleotide composition or evolutionary rates. Such data are relevant to strategies for conservation of existing decapod biodiversity, as well as elucidating the mechanisms and constraints shaping the patterns observed.FCT - SFRH/BD/25568/ 2006EC FP6 - GOCE-CT-2005-511234 HERMESFCT - PTDC/MAR/69892/2006 LusomarBo
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