23,578 research outputs found
THE INVESTMENT PROJECT PIPELINE COST ESCALATION, LEAD-TIME, SUCCESS, FAILURE AND SPEED1
As they involve expectations about the future and long lead times for planning and construction, the evolution of investment projects is usually complex and volatile. This paper analyses an important aspect of this volatility by studying the nature of the investment process, from the initial bright idea to the final construction and operational phase of a project. We refer to this process as the “project pipeline”. Using a rich source of information on recent Australian resource development projects, an index-number approach is employed to measure the escalation of costs of projects in the pipeline and the time spent there (the lead time). The determinants of the probability of ultimate success of projects is analysed with a binary choice model. Finally, a Markov chain approach is used to model the transitions of projects from one stage in the pipeline to the next, and to examine the implications of regulatory reform that has the effect of speeding up the flow of projects.
Mixed QCD and Weak Corrections to Production by Quark-Antiquark Annihilation
We report on our computation of the mixed QCD and weak corrections to including spin effects, in particular on
single top spin asymmetries.Comment: Talk given at "International Conference on QCD and Hadronic Physics",
Beijing, China, 16-20 Jun 200
Spin properties of top quark pairs produced at hadron colliders
We discuss the spin properties of top quark pairs produced at hadron
colliders at next-to-leading order in the coupling constant alpha_s of the
strong interaction. Specifically we present, for some decay channels, results
for differential angular distributions that are sensitive to t tbar spin
correlations.Comment: Invited talk given by A. Brandenburg at the Cracow epiphany
conference on heavy flavours, 3 - 6 January 2003, Cracow, Polan
Investigation of Top quark spin correlations at hadron collider
We report on our results about hadronic production at NLO QCD
including spin effects, especially on spin correlations.Comment: talk given at the 32nd International Conference on High Energy
Physics (ICHEP'04), Beijing, China, 16-22 Aug. 200
Unusual persistence of superconductivity against high magnetic fields in the strongly-correlated iron-chalcogenide film FeTe:O
We report an unusual persistence of superconductivity against high magnetic
fields in the iron chalcogenide film FeTe:O below ~ 2.5 K. Instead of
saturating like a mean-field behavior with a single order parameter, the
measured low-temperature upper critical field increases progressively,
suggesting a large supply of superconducting states accessible via magnetic
field or low-energy thermal fluctuations. We demonstrate that superconducting
states of finite momenta can be realized within the conventional theory,
despite its questionable applicability. Our findings reveal a fundamental
characteristic of superconductivity and electronic structure in the
strongly-correlated iron-based superconductors.Comment: 10 pages, 3 figure
Epitaxial Thin Films of the Giant-Dielectric-Constant Material CaCu_3Ti_4O_{12} Grown by Pulsed-laser Deposition
Pulsed-laser deposition has been used to grow epitaxial thin films of the
giant-dielectric-constant material CaCu_3Ti_4O_{12} on LaAlO_3 and SrTiO_3
substrates with or without various conducting buffer layers. The latter include
YBa_2Cu_3O_7, La_{1.85}Sr_{0.15}CuO_{4+\delta} and LaNiO_3. Above 100K - 150K
the thin films have a temperature independent dielectric constant as do single
crystals. The value of the dielectric constant is of the order of 1500 over a
wide temperature region, potentially making it a good candidate for many
applications. The frequency dependence of its dielectric properties below 100K
- 150K indicates an activated relaxation process.Comment: 11 pages, 4 figure
Top quark spin correlations at hadron colliders: Predictions at next-to-leading order QCD
The collider experiments at the Tevatron and the LHC will allow for detailed
investigations of the properties of the top quark. This requires precise
predictions of the hadronic production of pairs and of their
subsequent decays. In this Letter we present for the reactions the first calculation of the dilepton
angular distribution at next-to-leading order (NLO) in the QCD coupling,
keeping the full dependence on the spins of the intermediate state.
The angular distribution reflects the degree of correlation of the and
spins which we determine for different choices of and
spin bases. In the case of the Tevatron, the QCD corrections are sizeable, and
the distribution is quite sensitive to the parton content of the proton.Comment: 9 pages, 2 figure
Top Quark Pair Production and Decay including Spin Effects at Hadron Colliders: Predictions at NLO QCD
Top quark-antiquark () pairs will be produced copiously at the
Tevatron collider and in huge numbers at the LHC. This will make possible
detailed investigations of the properties and interactions of this quark
flavor. The analysis and interpretation of future data requires precise
predictions of the hadronic production of pairs and of their
subsequent decays. In this talk the reactions are considered and results are presented of our calculation
of the dilepton angular distribution at next-to-leading order QCD, keeping the
full dependence on the spins of the intermediate state. The angular
distribution is determined for different choices of reference axes that can be
identified with the and spin axes. While the QCD corrections to
the leading-order distribution turn out to be small in the case of the LHC, we
find them to be sizeable in the case of the Tevatron and find, moreover, the
angular distribution to be sensitive to the parton content of the proton.Comment: Talk given at 3rd Circum-Pan-Pacific Symposium on "High Energy Spin
Physics", Beijing, China, 8-13, 200
Birth/birth-death processes and their computable transition probabilities with biological applications
Birth-death processes track the size of a univariate population, but many
biological systems involve interaction between populations, necessitating
models for two or more populations simultaneously. A lack of efficient methods
for evaluating finite-time transition probabilities of bivariate processes,
however, has restricted statistical inference in these models. Researchers rely
on computationally expensive methods such as matrix exponentiation or Monte
Carlo approximation, restricting likelihood-based inference to small systems,
or indirect methods such as approximate Bayesian computation. In this paper, we
introduce the birth(death)/birth-death process, a tractable bivariate extension
of the birth-death process. We develop an efficient and robust algorithm to
calculate the transition probabilities of birth(death)/birth-death processes
using a continued fraction representation of their Laplace transforms. Next, we
identify several exemplary models arising in molecular epidemiology,
macro-parasite evolution, and infectious disease modeling that fall within this
class, and demonstrate advantages of our proposed method over existing
approaches to inference in these models. Notably, the ubiquitous stochastic
susceptible-infectious-removed (SIR) model falls within this class, and we
emphasize that computable transition probabilities newly enable direct
inference of parameters in the SIR model. We also propose a very fast method
for approximating the transition probabilities under the SIR model via a novel
branching process simplification, and compare it to the continued fraction
representation method with application to the 17th century plague in Eyam.
Although the two methods produce similar maximum a posteriori estimates, the
branching process approximation fails to capture the correlation structure in
the joint posterior distribution
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