572,572 research outputs found
Science and Theology: A Working Synthesis
Theologians and scientists, working independently, have provided worldviews that lead to questions about the meaning of existence and human life. When these disciplines interact, opportunity exists for more profound insight. Two individuals, Johannes Kepler in the sixteenth century and Pierre Teilhard de Chardin in the twentieth, attempted theological reconstructions based on revolutionary theories of their eras. Informed by a fierce faith in God and a rigorous pursuit of truth derived from the scientific method, their attempts at synthesizing these fields led to results that were unexpected, even unwanted. Yet they provide lessons in the present age for interpretations of the new discoveries and the responsibility of humankind to play an active role in the modern creation story
Semi-parametric estimation of the hazard function in a model with covariate measurement error
We consider a model where the failure hazard function, conditional on a
covariate is given by ,
with . The baseline
hazard function and relative risk belong both
to parametric families. The covariate is measured through the error model
where is independent from , with known density
. We observe a -sample , , where
is the minimum between the failure time and the censoring time, and
is the censoring indicator. We aim at estimating in presence
of the unknown density . Our estimation procedure based on least squares
criterion provide two estimators. The first one minimizes an estimation of the
least squares criterion where is estimated by density deconvolution. Its
rate depends on the smoothnesses of and as a
function of ,. We derive sufficient conditions that ensure the
-consistency. The second estimator is constructed under conditions
ensuring that the least squares criterion can be directly estimated with the
parametric rate. These estimators, deeply studied through examples are in
particular -consistent and asymptotically Gaussian in the Cox model
and in the excess risk model, whatever is
Social studies references in six Rhode Island high schools
Thesis (Ed.M.)--Boston Universit
Signatures of the Martian rotation parameters in the Doppler and range observables
The position of a Martian lander is affected by different aspects of Mars'
rotational motions: the nutations, the precession, the length-of-day variations
and the polar motion. These various motions have a different signature in a
Doppler observable between the Earth and a lander on Mars' surface. Knowing the
correlations between these signatures and the moments when these signatures are
not null during one day or on a longer timescale is important to identify
strategies that maximize the geophysical return of observations with a geodesy
experiment, in particular for the ones on-board the future NASA InSight or
ESA-Roscosmos ExoMars2020 missions.
We provide first-order formulations of the signature of the rotation
parameters in the Doppler and range observables. These expressions are
functions of the diurnal rotation of Mars, the lander position, the planet
radius and the rotation parameter. Additionally, the nutation signature in the
Doppler observable is proportional to the Earth declination with respect to
Mars.
For a lander on Mars close to the equator, the motions with the largest
signature in the Doppler observable are due to the length-of-day variations,
the precession rate and the rigid nutations. The polar motion and the liquid
core signatures have a much smaller amplitude. For a lander closer to the pole,
the polar motion signature is enhanced while the other signatures decrease.
We also numerically evaluate the amplitudes of the rotation parameters
signature in the Doppler observable for landers on other planets or moons.Comment: 30 pages 7 figures, In press PS
Real Option Valuation of a Portfolio of Oil Projects
Various methodologies exist for valuing companies and their projects. We address the problem of valuing a portfolio of projects within companies that have infrequent, large and volatile cash flows. Examples of this type of company exist in oil exploration and development and we will use this example to illustrate our analysis throughout the thesis. The theoretical interest in this problem lies in modeling the sources of risk in the projects and their different interactions within each project. Initially we look at the advantages of real options analysis and compare this approach with more traditional valuation methods, highlighting strengths and weaknesses ofeach approach in the light ofthe thesis problem. We give the background to the stages in an oil exploration and development project and identify the main common sources of risk, for example commodity prices. We discuss the appropriate representation for oil prices; in short, do oil prices behave more like equities or more like interest rates? The appropriate representation is used to model oil price as a source ofrisk. A real option valuation model based on market uncertainty (in the form of oil price risk) and geological uncertainty (reserve volume uncertainty) is presented and tested for two different oil projects. Finally, a methodology to measure the inter-relationship between oil price and other sources of risk such as interest rates is proposed using copula methods.Imperial Users onl
Similarities between the and Hubbard models in weakly correlated regimes
We present a comparative study of the Hubbard and models far away from
half-filling. We show that, at such fillings the Hamiltonian can be seen
as an effective model of the repulsive Hubbard Hamiltonian over the whole range
of correlation strength. Indeed, the range of the
Hubbard model can be mapped onto the finite range of the
model, provided that the effective exchange parameter is defined
variationally as the local singlet-triplet excitation energy. In this picture
the uncorrelated limit U=0 is associated with the super-symmetric point
and the infinitely correlated limit with the usual J=0
limit. A numerical comparison between the two models is presented using
different macroscopic and microscopic properties such as energies, charge gaps
and bond orders on a quarter-filled infinite chain. The usage of the
Hamiltonian in low-filled systems can therefore be a good alternative to the
Hubbard model in large time-consuming calculations.Comment: To be published in EPJB. 6 pages. 5 figure
Weak topologies for Linear Logic
We construct a denotational model of linear logic, whose objects are all the
locally convex and separated topological vector spaces endowed with their weak
topology. The negation is interpreted as the dual, linear proofs are
interpreted as continuous linear functions, and non-linear proofs as sequences
of monomials. We do not complete our constructions by a double-orthogonality
operation. This yields an interpretation of the polarity of the connectives in
terms of topology
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