832 research outputs found
Robust Monopoly Pricing: The Case of Regret
http://www.iue.it/PUB/ECO2005-10.pd
Interpretation of the angular dependence of the de Haas-van Alphen effect in MgB_2
We present detailed results for the amplitude and field dependence of the de
Haas-van Alphen (dHvA) signal arising from the electron-like sheet of
Fermi surface in MgB_2. Our data and analysis show that the dip in dHvA
amplitude when the field is close to the basal plane is caused by a beat
between two very similar dHvA frequencies and not a spin-zero effect as
previously assumed. Our results imply that the Stoner enhancement factors in
MgB_2 are small on both the Sigma and Pi sheets.Comment: 4 pages with figures. Submitted to PR
Complementary gradients in expression and binding of ELF-1 and Mek4 in development of the topographic retinotectal projection map
Peer reviewedPublisher PD
Damping of the de Haas-van Alphen oscillations in the superconducting state of MgB_2
The de Haas-van Alphen (dHvA) signal arising from orbits on the Fermi
surface sheet of the two-gap superconductor MgB has been observed in the
vortex state below . An extra attenuation of the dHvA signal, beyond
those effects described in the conventional Lifshitz-Kosevich expression, is
seen due to the opening of the superconducting gap. Our data show that the
band gap is still present up to . The data are compared to
current theories of dHvA oscillations in the superconducting state which allow
us to extract estimates for the evolution of the band gap with magnetic
field. Contrary to results for other materials, we find that the most recent
theories dramatically underestimate the damping in MgB.Comment: 10 pages with figures. Submitted to Phys. Rev. B. PDF version with
higher quality figures can be found at
http://www.phy.bris.ac.uk/research/cond_matt/PdfPubs/mgb2RSdhva.pd
Fermi Surface of 3d^1 Perovskite CaVO3 Near the Mott Transition
We present a detailed de Haas van Alphen effect study of the perovskite
CaVO3, offering an unprecedented test of electronic structure calculations in a
3d transition metal oxide. Our experimental and calculated Fermi surfaces are
in good agreement -- but only if we ignore large orthorhombic distortions of
the cubic perovskite structure. Subtle discrepancies may shed light on an
apparent conflict between the low energy properties of CaVO3, which are those
of a simple metal, and high energy probes which reveal strong correlations that
place CaVO3 on the verge of a metal-insulator transition.Comment: 4 pages, 4 figures (REVTeX
KNH2 - KH: a metal amide - hydride solid solution
We report for the first time the formation of a metal amide-hydride solid solution. The dissolution of KH into KNH2 leads to an anionic substitution, which decreases the interaction among NH2 - ions. The rotational properties of the high temperature polymorphs of KNH2 are thereby retained down to room temperature.Fil: Santoru, Antonio. Helmholtz-zentrum Geesthacht; Alemania. Università di Torino; ItaliaFil: Pistidda, Claudio. Helmholtz-zentrum Geesthacht; AlemaniaFil: Sørby, Magnus H.. Institute for Energy Technology. Physics Department; NoruegaFil: Chierotti, Michele R.. Università di Torino; ItaliaFil: Garroni, Sebastian. University of Sassari; ItaliaFil: Pinatel, Eugenio. Università di Torino; ItaliaFil: Karimi, Fahim. Helmholtz-zentrum Geesthacht; AlemaniaFil: Cao, Hujun. Helmholtz-zentrum Geesthacht; AlemaniaFil: Bergemann, Nils. Helmholtz-zentrum Geesthacht; AlemaniaFil: Le, Thi T.. Helmholtz-zentrum Geesthacht; AlemaniaFil: Puszkiel, Julián Atilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Gobetto, Roberto. Università di Torino; ItaliaFil: Baricco, Marcello. Università di Torino; ItaliaFil: Hauback, Bjorn C.. Institute for Energy Technology. Physics Department; NoruegaFil: Klassen, Thomas. Helmholtz-zentrum Geesthacht; AlemaniaFil: Dornheim, Martín. Helmholtz-zentrum Geesthacht; Alemani
Analysis of stellar spectra with 3D and NLTE models
Models of radiation transport in stellar atmospheres are the hinge of modern
astrophysics. Our knowledge of stars, stellar populations, and galaxies is only
as good as the theoretical models, which are used for the interpretation of
their observed spectra, photometric magnitudes, and spectral energy
distributions. I describe recent advances in the field of stellar atmosphere
modelling for late-type stars. Various aspects of radiation transport with 1D
hydrostatic, LTE, NLTE, and 3D radiative-hydrodynamical models are briefly
reviewed.Comment: 21 pages, accepted for publication as a chapter in "Determination of
Atmospheric Parameters of B, A, F and G Type Stars", Springer (2014), eds. E.
Niemczura, B. Smalley, W. Pyc
Persistent effectivity of gas plasma-treated, long time-stored liquid on epithelial cell adhesion capacity and membrane morphology
Research in plasma medicine includes a major interest in understanding gas plasma-cell interactions. The immediate application of gas plasma in vitro inhibits cell attachment, vitality and cell-cell contacts via the liquid. Interestingly, in our novel experiments described here we found that the liquid-mediated plasma effect is long-lasting after storage up to seven days; i. e. the liquid preserves the characteristics once induced by the argon plasma. Therefore, the complete Dulbecco's Modified Eagle cell culture medium was argon plasma-treated (atmospheric pressure, kINPen09) for 60 s, stored for several days (1, 4 and 7 d) at 37°C and added to a confluent mouse hepatocyte epithelial cell (mHepR1) monolayer. Impaired tight junction architecture as well as shortened microvilli on the cell membrane could be observed, which was accompanied by the loss of cell adhesion capacity. Online-monitoring of vital cells revealed a reduced cell respiration. Our first timedependent analysis of plasma-treated medium revealed that temperature, hydrogen peroxide production, pH and oxygen content can be excluded as initiators of cell physiological and morphological changes. The here observed persisting biological effects in plasma-treated liquids could open new medical applications in dentistry and orthopaedics
Chemical abundances of distant extremely metal-poor unevolved stars
Aims: The purpose of our study is to determine the chemical composition of a
sample of 16 candidate Extremely Metal-Poor (EMP) dwarf stars, extracted from
the Sloan Digital Sky Survey (SDSS). There are two main purposes: in the first
place to verify the reliability of the metallicity estimates derived from the
SDSS spectra; in the second place to see if the abundance trends found for the
brighter nearer stars studied previously also hold for this sample of fainter,
more distant stars. Methods: We used the UVES at the VLT to obtain
high-resolution spectra of the programme stars. The abundances were determined
by an automatic analysis with the MyGIsFOS code, with the exception of lithium,
for which the abundances were determined from the measured equivalent widths of
the Li I resonance doublet. Results: All candidates are confirmed to be EMP
stars, with [Fe/H]<= -3.0. The chemical composition of the sample of stars is
similar to that of brighter and nearer samples. We measured the lithium
abundance for 12 stars and provide stringent upper limits for three other
stars, for a fourth star the upper limit is not significant, owing to the low
signal-to noise ratio of the spectrum. The "meltdown" of the Spite plateau is
confirmed, but some of the lowest metallicity stars of the sample lie on the
plateau. Conclusions: The concordance of the metallicities derived from
high-resolution spectra and those estimated from the SDSS spectra suggests that
the latter may be used to study the metallicity distribution of the halo. The
abundance pattern suggests that the halo was well mixed for all probed
metallicities and distances. The fact that at the lowest metallicities we find
stars on the Spite plateau suggests that the meltdown depends on at least
another parameter, besides metallicity. (abridged)Comment: A&A in pres
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