8,845 research outputs found
Topological Josephson -junctions
We study the effect of a magnetic field on the current-phase relation of a
topological Josephson junction formed by connecting two superconductors through
the helical edge states of a quantum spin-Hall insulator. We predict that the
Zeeman effect along the spin quantization axis of the helical edges results in
an anomalous Josephson relation that allows for a supercurrent to flow in the
absence of superconducting phase bias. We relate the associated field-tunable
phase shift in the Josephson relation of such a -junction to
the existence of a so-called helical superconductivity, which may result from
the interplay of the Zeeman effect and spin-orbit coupling. We analyze the
dependence of the magneto-supercurrent on the junction length and discuss its
observability in suitably designed hybrid structures subject to an in-plane
magnetic field.Comment: 7 pages, 3 figures, Appendix and references adde
The neutron star inner crust and symmetry energy
The cell structure of clusters in the inner crust of a cold \beta-equilibrium
neutron star is studied within a Thomas Fermi approach and compared with other
approaches which include shell effects. Relativistic nuclear models are
considered. We conclude that the symmetry energy slope L may have quite
dramatic effects on the cell structure if it is very large or small. Rod-like
and slab-like pasta clusters have been obtained in all models except one with a
large slope L.Comment: 16 pages, 5 figure
Gaia Data Release 1. Cross-match with external catalogues - Algorithm and results
Although the Gaia catalogue on its own will be a very powerful tool, it is
the combination of this highly accurate archive with other archives that will
truly open up amazing possibilities for astronomical research. The advanced
interoperation of archives is based on cross-matching, leaving the user with
the feeling of working with one single data archive. The data retrieval should
work not only across data archives, but also across wavelength domains. The
first step for seamless data access is the computation of the cross-match
between Gaia and external surveys. The matching of astronomical catalogues is a
complex and challenging problem both scientifically and technologically
(especially when matching large surveys like Gaia). We describe the cross-match
algorithm used to pre-compute the match of Gaia Data Release 1 (DR1) with a
selected list of large publicly available optical and IR surveys. The overall
principles of the adopted cross-match algorithm are outlined. Details are given
on the developed algorithm, including the methods used to account for position
errors, proper motions, and environment; to define the neighbours; and to
define the figure of merit used to select the most probable counterpart.
Statistics on the results are also given. The results of the cross-match are
part of the official Gaia DR1 catalogue.Comment: 18 pages, 8 figures. Accepted for publication by A&
Quieting the Sharholders\u27 Voice: Empirical Evidence of Pervasive Bundling in Proxy Solicitations
The integrity of shareholder voting is critical to the legitimacy of corporate law. One threat to this process is proxy âbundling,â or the joinder of more than one separate item into a single proxy proposal. Bundling deprives shareholders of the right to convey their views on each separate matter being put to a vote and forces them to either reject the entire proposal or approve items they might not otherwise want implemented.
In this Paper, we provide the first comprehensive evaluation of the anti-bundling rules adopted by the Securities and Exchange Commission (âSECâ) in 1992. While we find that the courts have carefully developed a framework for the proper scope and application of the rules, the SEC and proxy advisory firms have been less vigilant in defending this instrumental shareholder right. In particular, we note that the most recent SEC interpretive guidance has undercut the effectiveness of the existing rules, and that, surprisingly, proxy advisory firms do not have well-defined heuristics to discourage bundling.
Building on the theoretical framework, this Article provides the first large-scale empirical study of bundling of management proposals. We develop four possible definitions of impermissible bundling and, utilizing a data set of over 1,300 management proposals, show that the frequency of bundling in our sample ranges from 6.2 percent to 28.8 percent (depending on which of the four bundling definitions is used). It is apparent that bundling occurs far more frequently than indicated by prior studies.
We further examine our data to report the items that are most frequently bundled and to analyze the proxy advisorsâ recommendations and the voting patterns associated with bundled proposals. This Article concludes with important implications for the SEC, proxy advisors, and institutional investors as to how each party can more effectively deter impermissible bundling and thus better protect the shareholder franchise
US market entry by Spanish pharmaceutical firms
This work explores the factors that spur firmsâ propensity to enter in international markets. Among the whole population of Spanish firms active in the pharmaceutical sector (over the period 1995-2004), we identify those firms that have entered the US market by assessing whether they have filed at least a trademark in the US Patents and Trademarks Office. By means of a hazard model, we empirically estimate which firmâs characteristics affect the probability of entry in the US market in a given year. Results show that technological capabilities (breadth and depth of firmsâ patent base), and the firmâs cost structure explain the entry in the US market with a branded product. Moreover, our evidence shows that entry strategies based on differentiation advantage (technological diversification) and strategies based on cost advantage (scale economies) are exclusive and do not mix well each otherForeign market entry, Internationalization strategies, Firm-Specific advantages, Competitive advantage, Innovation and R&D, Patents, Trademarks
Correlators of Hopf Wilson loops in the AdS/CFT correspondence
We study at quantum level correlators of supersymmetric Wilson loops with
contours lying on Hopf fibers of . In SYM theory the
strong coupling analysis can be performed using the AdS/CFT correspondence and
a connected classical string surface, linking two different fibers, is
presented. More precisely, the string solution describes oppositely oriented
fibers with the same scalar coupling and depends on an angular parameter,
interpolating between a non-BPS configuration and a BPS one. The system can be
thought as an alternative deformation of the ordinary antiparallel lines giving
the static quark-antiquark potential, that is indeed correctly reproduced, at
weak and strong coupling, as the fibers approach one another.Comment: 38 pages, 5 figure
Flow curvature effects on dynamic behaviour of a novel vertical axis tidal current turbine: numerical and experimental analysis
The paper deals with performances analysis of vertical axis turbine to exploit tidal marine currents. Flow curvature effects on performences of a novel vertical axis turbine have been investuigated. It has been shown that the flow curvature effect allows to design properly an accurate airfoil shape to increase turbine performances
The Equilibrium Photoionized Absorber in 3C351
We present two ROSAT PSPC observations of the radio-loud, lobe-dominated
quasar 3C 351, which shows an `ionized absorber' in its X-ray spectrum. The
factor 1.7 change in flux in the 2~years between the observations allows
a test of models for this ionized absorber.
The absorption feature at ~0.7 keV (quasar frame) is present in both spectra
but with a lower optical depth when the source intensity - and hence the
ionizing flux at the absorber - is higher, in accordance with a simple,
single-zone, equilibrium photoionization model. Detailed modeling confirms this
agrement quantitatively. The maximum response time of 2 years allows us to
limit the gas density: n_e > 2 x 10^4 cm^{-3}; and the distance of the ionized
gas from the central source R < 19 pc. This produces a strong test for a
photoionized absorber in 3C~351: a factor 2 flux change in ~1 week in this
source must show non-equilibrium effects in the ionized absorber.Comment: 10 pages, 3 figures, accepted by Ap
- âŠ