3,366 research outputs found
U.S. and Canadian Industrial Production Indices as Coupled Oscillators.
This paper explores the impact of different types of dynamical linkages (coupling) between the indices of industrial production for the U.S. and Canada. The Ozaki model provides an appropriate empirical framework for analyzing the dynamic path of each economy's productive activity because it provides an effective approximation to continuous time differential equations. We examine a combination of six different types of linkage between the indices of production. Major questions we study include whether the linkages increase or decrease the stability of the equilibrium paths, whether the linkages encourage or discourage business cycle oscillations, and whether the oscillations are synchronized.PRODUCTION ; PROJECTIONS ; ECONOMETRICS
Shape Space Methods for Quantum Cosmological Triangleland
With toy modelling of conceptual aspects of quantum cosmology and the problem
of time in quantum gravity in mind, I study the classical and quantum dynamics
of the pure-shape (i.e. scale-free) triangle formed by 3 particles in 2-d. I do
so by importing techniques to the triangle model from the corresponding 4
particles in 1-d model, using the fact that both have 2-spheres for shape
spaces, though the latter has a trivial realization whilst the former has a
more involved Hopf (or Dragt) type realization. I furthermore interpret the
ensuing Dragt-type coordinates as shape quantities: a measure of
anisoscelesness, the ellipticity of the base and apex's moments of inertia, and
a quantity proportional to the area of the triangle. I promote these quantities
at the quantum level to operators whose expectation and spread are then useful
in understanding the quantum states of the system. Additionally, I tessellate
the 2-sphere by its physical interpretation as the shape space of triangles,
and then use this as a back-cloth from which to read off the interpretation of
dynamical trajectories, potentials and wavefunctions. I include applications to
timeless approaches to the problem of time and to the role of uniform states in
quantum cosmological modelling.Comment: A shorter version, as per the first stage in the refereeing process,
and containing some new reference
Variation in alcohol dehydrogenase activity in vitro in flies from natural populations of Drosophila melanogaster.
uploaded by Plazi from Taxodro
The Mediterranean Way of Eating
Scientific evidence accumulated over decades validates the idea that a plant-based dietary pattern, such as the traditional Mediterranean way of eating, promotes health and plays an important role in risk reduction and prevention of several chronic diseases. One of the great advantages of the Mediterranean diet is that it can be easily adopted by other cultures because it is flexible and highly palatable. The Mediterranean Way of Eating: Evidence for Chronic Disease Prevention and Weight Management offers evidence-based information about an enjoyable, healthy way of eating that has stood the test of time, along with practical suggestions for incorporating the Mediterranean diet into your daily life. The first part of the book provides a brief history of the Mediterranean region and its different dietary influences. It discusses shared and unique foods in the coastal regions, and recent influences of processed foods and fast foods. It also presents scientific information on critical nutrients (macronutrients, vitamins, minerals, phytochemicals, antioxidants, and fiber) in foods found in the Mediterranean diets, how they function in the body, and why they are essential to health. The authors review the major chronic diseases, including obesity, type 2 diabetes, cardiovascular diseases, and certain cancers, and examine how a Mediterranean-style diet may help reduce risk or prevent these diseases. The second part of the book addresses the protective effects of foods and food components, discussing how Mediterranean diets may confer health benefits for reducing disease risk and managing weight. It examines the evidence-based health benefits for each of the food groups—such as fruits, vegetables, grains, fish, meat, dairy products, plus alcohol—along with suggestions for using the foods as part of a healthy diet. The last part of the book focuses on how to move toward a Mediterranean-style diet in your own life, eating at home or dining out, offering effective strategies for implementing the dietary changes
The use of exp(iS[x]) in the sum over histories
The use of as the generic form for a sum over histories in
configuration space is discussed critically and placed in its proper context.
The standard derivation of the sum over paths by discretizing the paths is
reviewed, and it is shown that the form is justified only
for Schrodinger-type systems which are at most second order in the momenta.
Extending this derivation to the relativistic free particle, the causal Green's
function is expressed as a sum over timelike paths, and the Feynman Green's
function is expressed both as a sum over paths which only go one way in time
and as a sum over paths which move forward and backward in time. The weighting
of the paths is shown not to be in any of these cases. The role
of the inner product and the operator ordering of the wave equation in defining
the sum over histories is discussed.Comment: 22 pages, Latex, Imperial-TP-92-93-4
Evolution of virulence: triggering host inflammation allows invading pathogens to exclude competitors.
Virulence is generally considered to benefit parasites by enhancing resource-transfer from host to pathogen. Here, we offer an alternative framework where virulent immune-provoking behaviours and enhanced immune resistance are joint tactics of invading pathogens to eliminate resident competitors (transferring resources from resident to invading pathogen). The pathogen wins by creating a novel immunological challenge to which it is already adapted. We analyse a general ecological model of 'proactive invasion' where invaders not adapted to a local environment can succeed by changing it to one where they are better adapted than residents. However, the two-trait nature of the 'proactive' strategy (provocation of, and adaptation to environmental change) presents an evolutionary conundrum, as neither trait alone is favoured in a homogenous host population. We show that this conundrum can be resolved by allowing for host heterogeneity. We relate our model to emerging empirical findings on immunological mediation of parasite competition
Proof for an upper bound in fixed-node Monte Carlo for lattice fermions
We justify a recently proposed prescription for performing Green Function
Monte Carlo calculations on systems of lattice fermions, by which one is able
to avoid the sign problem. We generalize the prescription such that it can also
be used for problems with hopping terms of different signs. We prove that the
effective Hamiltonian, used in this method, leads to an upper bound for the
ground-state energy of the real Hamiltonian, and we illustrate the
effectiveness of the method on small systems.Comment: 14 pages in revtex v3.0, no figure
Why you Can’t Use Water to Make Cryoporometric Measurements of the Pore Size Distributions in Meteorites – or in High Iron Content Clays, Rocks or Concrete.
Many porous materials have high susceptibility magnetic gradients in the pores, due to the presence of iron or other magnetic materials. Thus if probe liquids are placed in the pores they exhibit fast decaying signals with a short T2*. Usually the actual T2 of the liquids is also reduced, due the presence of paramagnetic ions in the pore walls. The usual solution in NMR is to measure an echo (or echo train) at short times. However, recent work [J. Phys.: Condens. Matter 19, 415117, 2007.] has shown that water/ice systems near a pore wall form rotator phase plastic ice, with T2 relaxation times in the region of 100 to 200 ms. Thus if a NMR cryoporometric measurement is attempted with a measurement time significantly less than 1 or 2 milli-seconds, the result is to make a measurement based on the phase properties of the brittle to plastic ice phase transition, not that of the brittle ice to water phase transition. This gives rise to artefacts of small pore sizes that may not actually be present. This work successfully uses a-polar liquids instead
Issues and Observations on Applications of the Constrained-Path Monte Carlo Method to Many-Fermion Systems
We report several important observations that underscore the distinctions
between the constrained-path Monte Carlo method and the continuum and lattice
versions of the fixed-node method. The main distinctions stem from the
differences in the state space in which the random walk occurs and in the
manner in which the random walkers are constrained. One consequence is that in
the constrained-path method the so-called mixed estimator for the energy is not
an upper bound to the exact energy, as previously claimed. Several ways of
producing an energy upper bound are given, and relevant methodological aspects
are illustrated with simple examples.Comment: 28 pages, REVTEX, 5 ps figure
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