1,096 research outputs found
The Demand for Directors' and Officers' Insurance in Canada
This paper looks at the insurance demand of a firm's directors and officers using a sample of Canadian corporations (excluding firms from the Financial services and Mining sectors) from 1993-1999. More to the point, we study the demand for director's and officer's insurance. Our results suggest that larger corporation are more likely to purchase D&O insurance. Firms that are strong financially are less likely to purchase D&O insurance. Firms are also less likely to purchase D&O insurance when there are many outsiders on the board of directors and when the board member have an important financial stake in the corporation. Surprisingly, being listed on a stock exchange in the United States does not seem to have an impact on the demand for D&O insurance, contrary to previous results. Cette recherche se penche sur la demande d'assurance de la responsabilité civile des administrateurs et des dirigeants d'entreprise en utilisant des données pour plus de 350 compagnies canadiennes entre 1993 et 1999. Les firmes dans les secteurs des services financiers et des mines ne sont pas inclues. Plus précisément, nous nous intéressons à la demande d'assurance de la responsabilité civile des administrateurs et des dirigeants. Nos résultats suggèrent qu'il est plus probable pour une corporation de grande taille d'avoir une assurance D&O que pour une corporation de petite taille. Les corporations qui ont une bonne santé financière ont moins de chance d'avoir une assurance, tout comme les corporations où la présence d'administrateurs indépendants au conseil d'administration est importante. De plus, plus les membres des conseils d'administration sont impliqués financièrement dans la santé d'une corporation, moins importante est la probabilité que cette compagnie possède une assurance D&O. Un résultat surprenant que nous obtenons est le fait que d'être enregistré dans une bourse américaine ne semble pas avoir d'impact sur la demande d'assurance D&O, contrairement aux études précédentes.Executive Compensation, D&O Insurance, Rémunération des dirigeants, assurance D&O
RBF neural net based classifier for the AIRIX accelerator fault diagnosis
The AIRIX facility is a high current linear accelerator (2-3.5kA) used for
flash-radiography at the CEA of Moronvilliers France. The general background of
this study is the diagnosis and the predictive maintenance of AIRIX. We will
present a tool for fault diagnosis and monitoring based on pattern recognition
using artificial neural network. Parameters extracted from the signals recorded
on each shot are used to define a vector to be classified. The principal
component analysis permits us to select the most pertinent information and
reduce the redundancy. A three layer Radial Basis Function (RBF) neural network
is used to classify the states of the accelerator. We initialize the network by
applying an unsupervised fuzzy technique to the training base. This allows us
to determine the number of clusters and real classes, which define the number
of cells on the hidden and output layers of the network. The weights between
the hidden and the output layers, realising the non-convex union of the
clusters, are determined by a least square method. Membership and ambiguity
rejection enable the network to learn unknown failures, and to monitor
accelerator operations to predict future failures. We will present the first
results obtained on the injector.Comment: 3 pages, 4 figures, LINAC'2000 conferenc
Average characteristic polynomials in the two-matrix model
The two-matrix model is defined on pairs of Hermitian matrices of
size by the probability measure where
and are given potential functions and \tau\in\er. We study averages
of products and ratios of characteristic polynomials in the two-matrix model,
where both matrices and may appear in a combined way in both
numerator and denominator. We obtain determinantal expressions for such
averages. The determinants are constructed from several building blocks: the
biorthogonal polynomials and associated to the two-matrix
model; certain transformed functions and \Q_n(v); and finally
Cauchy-type transforms of the four Eynard-Mehta kernels , ,
and . In this way we generalize known results for the
-matrix model. Our results also imply a new proof of the Eynard-Mehta
theorem for correlation functions in the two-matrix model, and they lead to a
generating function for averages of products of traces.Comment: 28 pages, references adde
Non-colliding Brownian Motions and the extended tacnode process
We consider non-colliding Brownian motions with two starting points and two
endpoints. The points are chosen so that the two groups of Brownian motions
just touch each other, a situation that is referred to as a tacnode. The
extended kernel for the determinantal point process at the tacnode point is
computed using new methods and given in a different form from that obtained for
a single time in previous work by Delvaux, Kuijlaars and Zhang. The form of the
extended kernel is also different from that obtained for the extended tacnode
kernel in another model by Adler, Ferrari and van Moerbeke. We also obtain the
correlation kernel for a finite number of non-colliding Brownian motions
starting at two points and ending at arbitrary points.Comment: 38 pages. In the revised version a few arguments have been expanded
and many typos correcte
Non-intersecting squared Bessel paths at a hard-edge tacnode
The squared Bessel process is a 1-dimensional diffusion process related to
the squared norm of a higher dimensional Brownian motion. We study a model of
non-intersecting squared Bessel paths, with all paths starting at the same
point at time and ending at the same point at time . Our
interest lies in the critical regime , for which the paths are tangent
to the hard edge at the origin at a critical time . The critical
behavior of the paths for is studied in a scaling limit with time
and temperature . This leads to a critical
correlation kernel that is defined via a new Riemann-Hilbert problem of size
. The Riemann-Hilbert problem gives rise to a new Lax pair
representation for the Hastings-McLeod solution to the inhomogeneous Painlev\'e
II equation where with
the parameter of the squared Bessel process. These results extend
our recent work with Kuijlaars and Zhang \cite{DKZ} for the homogeneous case
.Comment: 54 pages, 13 figures. Corrected error in Theorem 2.
Multi-wavelength observations of 3FGL J2039.6-5618: a candidate redback millisecond pulsar
We present multi-wavelength observations of the unassociated gamma-ray source
3FGL J2039.6-5618 detected by the Fermi Large Area Telescope. The source
gamma-ray properties suggest that it is a pulsar, most likely a millisecond
pulsar, for which neither radio nor -ray pulsations have been detected
yet. We observed 3FGL J2039.6-5618 with XMM-Newton and discovered several
candidate X-ray counterparts within/close to the gamma-ray error box. The
brightest of these X-ray sources is variable with a period of 0.22450.0081
d. Its X-ray spectrum can be described by a power law with photon index
, and hydrogen column density cm, which gives an unabsorbed 0.3--10 keV X-ray flux of erg cm s. Observations with the Gamma-Ray Burst
Optical/Near-Infrared Detector (GROND) discovered an optical counterpart to
this X-ray source, with a time-average magnitude . The counterpart
features a flux modulation with a period of 0.227480.00043 d that
coincides, within the errors, with that of the X-ray source, confirming the
association based on the positional coincidence. We interpret the observed
X-ray/optical periodicity as the orbital period of a close binary system where
one of the two members is a neutron star. The light curve profile of the
companion star, with two asymmetric peaks, suggests that the optical emission
comes from two regions at different temperatures on its tidally-distorted
surface. Based upon its X-ray and optical properties, we consider this source
as the most likely X-ray counterpart to 3FGL J2039.6-5618, which we propose to
be a new redback system.Comment: 35 pages, 8 figures, accepted for publication on Astrophysical
Journa
Correlation between the optical veiling and accretion properties: A case study of the classical T Tauri star DK Tau
Classical T Tauri stars (cTTs) accrete from their circumstellar disk. The
material falls onto the stellar surface, producing an accretion shock, which
generates veiling in a star's spectra. In addition, the shock causes a
localized accretion spot at the level of the chromosphere. Our goal is to
investigate the accretion, particularly the mass accretion rates (Macc), for
the cTTs DK Tau, over two periods of 17 and 29 days, using two different
procedures for comparison purposes. The first method relies on the derivation
of the accretion luminosity via accretion-powered emission lines. The second
compares the variability of the optical veiling with accretion shock models to
determine mass accretion rates. We used observations taken in 2010 and 2012
with the ESPaDOnS spectropolarimeter at the CFHT. We find peak values of the
veiling (at 550 nm) ranging from 0.2 to 1.3, with a steeper trend across the
wavelength range for higher peak values. When using the accretion-powered
emission lines, we find mass accretion rate values ranging from
log(Macc[Msol/yr]) = -8.20 to log(Macc[Msol/yr]) = -7.40. This agrees with the
values found in the literature, as well as the values calculated using the
accretion shock models and the veiling. In addition, we identify a power-law
correlation between the values of the accretion luminosity and the optical
veiling. For the 2010 observations, using the values of the filling factors
(which represent the area of the star covered by an accretion spot) derived
from the shock models, we infer that the accretion spot was located between +45
degrees and +75 degrees in latitude. We show that both methods of determining
the mass accretion rate yield similar results. We also present a helpful means
of confirming the accretion luminosity values by measuring the veiling at a
single wavelength in the optical
Recognition of the latency-associated immediate early protein IE63 of varicella-zoster virus by human memory T-lymphocytes
peer reviewedVaricella-zoster virus (VZV) is a human alpha herpesvirus that establishes latency in sensory ganglia. Latency is characterized by the abundant expression of the immediate early protein 63 (IE63), whereas other viral proteins have not yet been detected during the quiescent phase of VZV infection. The IE63 protein is a component of the virion and is expressed very early in the infectious cycle. The IE63 protein is also expressed in skin during episodes of varicella and herpes zoster. We have evaluated the cell-mediated immune response against IE63 in naturally immune adults with a history of chickenpox, by T lymphoproliferation and cytotoxicity assays. Among donors who had T cell proliferation to unfractionated VZV Ags from infected cell extract, 59% had T cell recognition of purified IE63. The CTL response to IE63 was equivalent to CTL recognition of IE62, the major tegument component of VZV whose immunogenicity has been previously described. IgG Abs against IE63 were detected in serum from healthy immune adults. These results indicate that IE63 is an important target of immunity to VZV. T cell recognition of IE63 is likely to be involved in controlling VZV reactivation from latency
A family of Nikishin systems with periodic recurrence coefficients
Suppose we have a Nikishin system of measures with the th generating
measure of the Nikishin system supported on an interval \Delta_k\subset\er
with for all . It is well known that
the corresponding staircase sequence of multiple orthogonal polynomials
satisfies a -term recurrence relation whose recurrence coefficients,
under appropriate assumptions on the generating measures, have periodic limits
of period . (The limit values depend only on the positions of the intervals
.) Taking these periodic limit values as the coefficients of a new
-term recurrence relation, we construct a canonical sequence of monic
polynomials , the so-called \emph{Chebyshev-Nikishin
polynomials}. We show that the polynomials themselves form a sequence
of multiple orthogonal polynomials with respect to some Nikishin system of
measures, with the th generating measure being absolutely continuous on
. In this way we generalize a result of the third author and Rocha
\cite{LopRoc} for the case . The proof uses the connection with block
Toeplitz matrices, and with a certain Riemann surface of genus zero. We also
obtain strong asymptotics and an exact Widom-type formula for the second kind
functions of the Nikishin system for .Comment: 30 pages, minor change
Determinants of institutional delivery among young married women in Nepal: Evidence from the Nepal Demographic and Health Survey, 2011
OBJECTIVES: To identify the determinants of institutional
delivery among young married women in Nepal. DESIGN: Nepal
Demographic and Health Survey (NDHS) data sets 2011 were
analysed. Bivariate and multivariate logistic regression
analyses were performed using a subset of 1662 ever-married
young women (aged 15-24 years). OUTCOME MEASURE: Place of
delivery. RESULTS: The rate of institutional delivery among
young married women was 46%, which is higher than the national
average (35%) among all women of reproductive age. Young women
who had more than four antenatal care (ANC) visits were three
times more likely to deliver in a health institution compared
with women who had no antenatal care visit (OR: 3.05; 95% CI:
2.40 to 3.87). The probability of delivering in an institution
was 69% higher among young urban women than among young women
who lived in rural areas. Young women who had secondary or above
secondary level education were 1.63 times more likely to choose
institutional delivery than young women who had no formal
education (OR: 1.626; 95% CI: 1.171 to 2.258). Lower use of a
health institution for delivery was also observed among poor
young women. Results showed that wealthy young women were 2.12
times more likely to deliver their child in an institution
compared with poor young women (OR: 2.107; 95% CI: 1.53 to
2.898). Other factors such as the age of the young woman,
religion, ethnicity, and ecological zone were also associated
with institutional delivery. CONCLUSIONS: Maternal health
programs should be designed to encourage young women to receive
adequate ANC (at least four visits). Moreover, health programs
should target poor, less educated, rural, young women who live
in mountain regions, are of Janajati ethnicity and have at least
one child as such women are less likely to choose institutional
delivery in Nepal
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