5,308 research outputs found
The Discretionary Effect of CEOs and Board Chairs on Corporate Governance Structures
In this study we analyze the effect of latent managerial characteristics on corporate governance. We find that CEO and board chair fixed effects explain a significant portion of the variation in board size, board independence, and CEO-chair duality even after controlling for several firm characteristics and firm fixed effects. The effect of CEOs on corporate governance practices is attributable mainly to executives who simultaneously hold the position of CEO and board chair in the same firm. Our results do not show a decline in CEO discretionary influence on corporate governance after the enactment of the Sarbanes–Oxley Act and stock exchange governance regulations
The role of magnetic field for quiescence-outburst models in CVs
In this paper we present the elementary assumptions of our research on the
role of the magnetic field in modelling the quiescence-outbursts cycle in
Cataclysmic Variables (CVs). The behaviour of the magnetic field is crucial not
only to integrate the disk instability model (Osaki 1974), but also to
determine the cause and effect nexus among parameters affecting the behavior of
complex systems. On the ground of our interpretation of the results emerging
from the literature, we suggest that in models describing DNe outbursts, such
as the disk instability model, the secondary instability model (Bath 1973) and
the thermonuclear runaway model (Mitrofanov 1978), the role of the magnetic
field is at least twofold. On the one hand, it activates a specific dynamic
pathway for the accreting matter by channelling it. On the other hand, it could
be indirectly responsible for switching a particular outburst modality. In
order to represent these two roles of the magnetic field, we need to integrate
the disk instability model by looking at the global behaviour of the system
under analysis. Stochastic resonance in dynamo models, we believe, is a
suitable candidate for accomplishing this task. We shall present the MHD model
including this mechanism elsewhere.Comment: 5 pages, 2 figures, CTU Proceedings, Acta Polytechnica (accepted
The Flash Crash: An Examination of Shareholder Wealth and Market Quality
We investigate stock returns, market quality, and options market activity around the flash crash of May 6, 2010. Abnormal returns are negative on the day of and the day after the flash crash for stocks that had trades that executed during the crash subsequently cancelled by either Nasdaq or NYSE Arca. Consistent with studies that suggest that other sources of liquidity withdrew from the markets during the flash crash, we find that the fraction of trades executed by the NYSE increases during this volatile period. Market quality deteriorates following the flash crash as bid-ask spreads increase and quote depths decrease. Evidence from the options markets indicates that investor uncertainty increased around the time of the crash and remained elevated for several days
Telescope performance and image simulations of the balloon-borne coded-mask protoMIRAX experiment
In this work we present the results of imaging simulations performed with the
help of the GEANT4 package for the protoMIRAX hard X-ray balloon experiment.
The instrumental background was simulated taking into account the various
radiation components and their angular dependence, as well as a detailed mass
model of the experiment. We modeled the meridian transits of the Crab Nebula
and the Galatic Centre region during balloon flights in Brazil ( of latitude and an altitude of km) and
introduced the correspondent spectra as inputs to the imaging simulations. We
present images of the Crab and of three sources in the Galactic Centre region:
1E 1740.7-2942, GRS 1758-258 and GX 1+4. The results show that the protoMIRAX
experiment is capable of making spectral and timing observations of bright hard
X-ray sources as well as important imaging demonstrations that will contribute
to the design of the MIRAX satellite mission.Comment: 9 figure
The Dairy Sector of Brazil: A Country Study
Agribusiness, International Development, International Relations/Trade,
Korea and the BICs (Brazil, India and China) : catching up experiences
This paper tests a neo-Schumpeterian model with industry-level data to analyze how Brazil, India, and China are catching up with South Korea’s technological frontier in a globalized world. The paper validates Aghion et al.’s inverted-U hypothesis that industries that are closer to the technological frontier innovate to escape competition while longer distances discourage innovating. It suggests that for effective catching up, distance-shortening (or innovation-enhancing) policies may be a necessary complement to liberalization. South Korea and China combined a variety of distance-shortening policies with financial subsidies to promote high tech industries and an export-led growth strategy. Post-liberalization, they leveraged swift competition to spur catch-up. In comparison, Brazil, which was as rich as South Korea, and India, which was as rich as China in 1980, are catching up more slowly. Import-substitution industrialization strategies saddled Brazil and India with a large anti-export bias, and unfocused attention to innovation-enhancing policies dampened global competitiveness. Post liberalization, many of their industries were too far behind the technological frontier to effectively benefit from competition. The catch-up experiences of Brazil, India, and China with South Korea illustrate that distance from the technological frontier matters and that the design of country-specific distance- shortening policies can be an important complement to trade liberalization in promoting catching up with richer countries.Labor Policies,Economic Theory&Research,Water and Industry,E-Business,Knowledge for Development
Theoretical study of molecular electronic excitations and optical transitions of C60
We report results on ab initio calculations of excited states of the
fullerene molecule by using configuration interaction (CI) approach with singly
excited determinants (SCI). We have used both the experimental geometry and the
one optimized by the density functional method and worked with basis sets at
the cc-pVTZ and aug-cc-pVTZ level. Contrary to the early SCI semiempirical
calculations, we find that two lowest electron
optical lines are situated at relatively high energies of ~5.8 eV (214 nm) and
~6.3 eV (197 nm). These two lines originate from two transitions: from HOMO to (LUMO+1) () and from (HOMO--1)
to LUMO (). The lowest molecular excitation, which is the level, is found at ~2.5 eV. Inclusion of doubly excited determinants
(SDCI) leads only to minor corrections to this picture. We discuss possible
assignment of absorption bands at energies smaller than 5.8 eV (or
larger than 214 nm).Comment: 6 pages, 1 figure, 9 Table
On a new theoretical framework for RR Lyrae stars I: the metallicity dependence
We present new nonlinear, time-dependent convective hydrodynamical models of
RR Lyrae stars computed assuming a constant helium-to-metal enrichment ratio
and a broad range in metal abundances (Z=0.0001--0.02). The stellar masses and
luminosities adopted to construct the pulsation models were fixed according to
detailed central He burning Horizontal Branch evolutionary models. The
pulsation models cover a broad range in stellar luminosity and effective
temperatures and the modal stability is investigated for both fundamental and
first overtones. We predict the topology of the instability strip as a function
of the metal content and new analytical relations for the edges of the
instability strip in the observational plane. Moreover, a new analytical
relation to constrain the pulsation mass of double pulsators as a function of
the period ratio and the metal content is provided. We derive new
Period-Radius-Metallicity relations for fundamental and first-overtone
pulsators. They agree quite well with similar empirical and theoretical
relations in the literature. From the predicted bolometric light curves,
transformed into optical (UBVRI) and near-infrared (JHK) bands, we compute the
intensity-averaged mean magnitudes along the entire pulsation cycle and, in
turn, new and homogenous metal-dependent (RIJHK) Period-Luminosity relations.
Moreover, we compute new dual and triple band optical, optical--NIR and NIR
Period-Wesenheit-Metallicity relations. Interestingly, we find that the optical
Period-W(V,B-V) is independent of the metal content and that the accuracy of
individual distances is a balance between the adopted diagnostics and the
precision of photometric and spectroscopic datasets.Comment: 51 pages, 20 figures, 9 tables, accepted for publication on Ap
Rheology as a tool to follow hybrid nanocomposites preparation
Hybrid nanocomposites were prepared using two polymeric matrices and the one inorganic precursor. Rheological measurements were performed in order to characterize and follow the reactions and to assess the effect of temperature and time on the nanocomposite structure. The experimental results evidenced that crosslinking occurs for both polymers. Higher crosslinking density and well dispersed nanoparticles morphology were achieved with EVA.The authors acknowledge the Foundation for Science and Technology (FCT) Project SFRH/BD/39085/2007 for the financial support
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