281 research outputs found
Markups and Oil Prices in Canada
The markup (the ratio of price to marginal cost) in Canada has risen steadily since
the early 1990s suggesting a widening gap between the actual and the efficient level of
output and a declining share of labour income in GDP. It exhibits non-stationary movements
over the sample period 1982Q1 to 2009Q4, allowing us to identify a permanent
markup shock. We provide evidence that oil price movements are important for understanding
the behaviour of the markup, and separately identify both oil price shocks
and permanent non-oil markup shocks. Our key findings are: (1) oil price shocks and
non-oil markup shocks account for 50 to 80 percent of the variation in the markup, with
the former dominating at shorter horizons; (2) the role of oil price shocks is prominent
in accounting for the upward trend in the markup since the mid-1990s; (3) the direct
effects of oil prices on the markup in the mining sector (which includes the oil-producing
sector) have contributed the most to the upward trend in the aggregate markup; and
(4) other explanations such as market structure shifts, trend inflation movements and
the falling relative price of investment do not appear to account for the behaviour of
the markup
The dynamics of quark-gluon plasma and AdS/CFT
In these pedagogical lectures, we present the techniques of the AdS/CFT
correspondence which can be applied to the study of real time dynamics of a
strongly coupled plasma system. These methods are based on solving
gravitational Einstein's equations on the string/gravity side of the AdS/CFT
correspondence. We illustrate these techniques with applications to the
boost-invariant expansion of a plasma system. We emphasize the common
underlying AdS/CFT description both in the large proper time regime where
hydrodynamic dynamics dominates, and in the small proper time regime where the
dynamics is far from equilibrium. These AdS/CFT methods provide a fascinating
arena interrelating General Relativity phenomenae with strongly coupled gauge
theory physics.Comment: 35 pages, 3 figures. Lectures at the 5th Aegean summer school, `From
gravity to thermal gauge theories: the AdS/CFT correspondence'. To appear in
the proceedings in `Lecture Notes in Physics
antiSMASH 3.0—a comprehensive resource for the genome mining of biosynthetic gene clusters
Microbial secondary metabolism constitutes a rich source of antibiotics, chemotherapeutics, insecticides and other high-value chemicals. Genome mining of gene clusters that encode the biosynthetic pathways for these metabolites has become a key methodology for novel compound discovery. In 2011, we introduced antiSMASH, a web server and stand-alone tool for the automatic genomic identification and analysis of biosynthetic gene clusters, available at http://antismash.secondarymetabolites.org. Here, we present version 3.0 of antiSMASH, which has undergone major improvements. A full integration of the recently published ClusterFinder algorithm now allows using this probabilistic algorithm to detect putative gene clusters of unknown types. Also, a new dereplication variant of the ClusterBlast module now identifies similarities of identified clusters to any of 1172 clusters with known end products. At the enzyme level, active sites of key biosynthetic enzymes are now pinpointed through a curated pattern-matching procedure and Enzyme Commission numbers are assigned to functionally classify all enzyme-coding genes. Additionally, chemical structure prediction has been improved by incorporating polyketide reduction states. Finally, in order for users to be able to organize and analyze multiple antiSMASH outputs in a private setting, a new XML output module allows offline editing of antiSMASH annotations within the Geneious software
Green function techniques in the treatment of quantum transport at the molecular scale
The theoretical investigation of charge (and spin) transport at nanometer
length scales requires the use of advanced and powerful techniques able to deal
with the dynamical properties of the relevant physical systems, to explicitly
include out-of-equilibrium situations typical for electrical/heat transport as
well as to take into account interaction effects in a systematic way.
Equilibrium Green function techniques and their extension to non-equilibrium
situations via the Keldysh formalism build one of the pillars of current
state-of-the-art approaches to quantum transport which have been implemented in
both model Hamiltonian formulations and first-principle methodologies. We offer
a tutorial overview of the applications of Green functions to deal with some
fundamental aspects of charge transport at the nanoscale, mainly focusing on
applications to model Hamiltonian formulations.Comment: Tutorial review, LaTeX, 129 pages, 41 figures, 300 references,
submitted to Springer series "Lecture Notes in Physics
Active Brownian Particles. From Individual to Collective Stochastic Dynamics
We review theoretical models of individual motility as well as collective
dynamics and pattern formation of active particles. We focus on simple models
of active dynamics with a particular emphasis on nonlinear and stochastic
dynamics of such self-propelled entities in the framework of statistical
mechanics. Examples of such active units in complex physico-chemical and
biological systems are chemically powered nano-rods, localized patterns in
reaction-diffusion system, motile cells or macroscopic animals. Based on the
description of individual motion of point-like active particles by stochastic
differential equations, we discuss different velocity-dependent friction
functions, the impact of various types of fluctuations and calculate
characteristic observables such as stationary velocity distributions or
diffusion coefficients. Finally, we consider not only the free and confined
individual active dynamics but also different types of interaction between
active particles. The resulting collective dynamical behavior of large
assemblies and aggregates of active units is discussed and an overview over
some recent results on spatiotemporal pattern formation in such systems is
given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte
Antiprotons in cosmic rays from neutralino annihilation
We calculate the antiproton flux due to relic neutralino annihilations, in a
two-dimensional diffusion model compatible with stable and radioactive cosmic
ray nuclei. We find that the uncertainty in the primary flux induced by the
propagation parameters alone is about two orders of magnitude at low energies,
and it is mainly determined by the lack of knowledge on the thickness of the
diffusive halo. On the contrary, different dark matter density profiles do not
significantly alter the flux: a NFW distribution produces fluxes which are at
most 20% higher than an isothermal sphere. The most conservative choice for
propagation parameters and dark matter distribution normalization, together
with current data on cosmic antiprotons, cannot lead to any definitive
constraint on the supersymmetric parameter space, neither in a low-energy
effective MSSM, or in a minimal SUGRA scheme. However, if the best choice for
propagation parameters - corresponding to a diffusive halo of L=4 kpc - is
adopted, some supersymmetric configurations with the neutralino mass of about
100 GeV should be considered as excluded. An enhancement flux factor - due for
instance to a clumpy dark halo or to a higher local dark matter density - would
imply a more severe cut on the supersymmetric parameters.Comment: 23 pages, 2 tables and 19 figures, typeset with ReVTeX4. The paper
may also be found at http://www.to.infn.it/~fornengo/papers/pbar03.ps.gz or
through http://www.to.infn.it/astropart/index.html A subsection added. Final
version to appear in PR
A search for the decay
We search for the rare flavor-changing neutral-current decay in a data sample of 82 fb collected with the {\sl BABAR}
detector at the PEP-II B-factory. Signal events are selected by examining the
properties of the system recoiling against either a reconstructed hadronic or
semileptonic charged-B decay. Using these two independent samples we obtain a
combined limit of
at the 90% confidence level. In addition, by selecting for pions rather than
kaons, we obtain a limit of using only the hadronic B reconstruction method.Comment: 7 pages, 8 postscript figures, submitted to Phys. Rev. Let
High-reflectivity broadband distributed Bragg reflector lattice matched to ZnTe
We report on the realization of a high quality distributed Bragg reflector
with both high and low refractive index layers lattice matched to ZnTe. Our
structure is grown by molecular beam epitaxy and is based on binary compounds
only. The high refractive index layer is made of ZnTe, while the low index
material is made of a short period triple superlattice containing MgSe, MgTe,
and ZnTe. The high refractive index step of Delta_n=0.5 in the structure
results in a broad stopband and the reflectivity coefficient exceeding 99% for
only 15 Bragg pairs.Comment: 4 pages, 3 figure
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