15,594 research outputs found
A Finslerian version of 't Hooft Deterministic Quantum Models
Using the Finsler structure living in the phase space associated to the
tangent bundle of the configuration manifold, deterministic models at the
Planck scale are obtained. The Hamiltonian function are constructed directly
from the geometric data and some assumptions concerning time inversion
symmetry. The existence of a maximal acceleration and speed is proved for
Finslerian deterministic models. We investigate the spontaneous symmetry
breaking of the orthogonal symmetry SO(6N) of the Hamiltonian of a
deterministic system. This symmetry break implies the non-validity of the
argument used to obtain Bell's inequalities for spin states. It is introduced
and motivated in the context of Randers spaces an example of simple 't Hooft
model with interactions.Comment: 25 pages; no figures. String discussion deleted. Some minor change
Two distinct desynchronization processes caused by lesions in globally coupled neurons
To accomplish a task, the brain works like a synchronized neuronal network
where all the involved neurons work together. When a lesion spreads in the
brain, depending on its evolution, it can reach a significant portion of
relevant area. As a consequence, a phase transition might occur: the neurons
desynchronize and cannot perform a certain task anymore. Lesions are
responsible for either disrupting the neuronal connections or, in some cases,
for killing the neuron. In this work, we will use a simplified model of
neuronal network to show that these two types of lesions cause different types
of desynchronization.Comment: 5 pages, 3 figure
Boundary conditions and renormalized stress-energy tensor on a Poincar\'e patch of
Quantum field theory on anti-de Sitter spacetime requires the introduction of
boundary conditions at its conformal boundary, due essentially to the absence
of global hyperbolicity. Here we calculate the renormalized stress-energy
tensor for a scalar field on the Poincar\'e patch of
and study how it depends on those boundary conditions. We show
that, except for the Dirichlet and Neumann cases, the boundary conditions break
the maximal invariance. As a result,
acquires a space dependence and is no longer
proportional to the metric. When the physical quantities are expanded in a
parameter which characterizes the boundary conditions (with
corresponding to Dirichlet and corresponding to Neumann), the
singularity of the Green's function is entirely subtracted at zeroth order in
. As a result, the contribution of nontrivial boundary conditions to the
stress-energy tensor is free of singular terms.Comment: 7 pages. Minor Correction. Matches published versio
Wealth Effects in Emerging Market Economies
We build a panel of 14 emerging economies to estimate the magnitude of housing, stock market, and money wealth effects on consumption. Using modern panel data econometric techniques and quarterly data for the period 1990/1-2008/2, we show that; (i) wealth effects are statistically significant and relatively large in magnitude; (ii) housing wealth effects tend to be smaller for Asian emerging markets while stock markets wealth effects are, in general, smaller for Latin American countries; (iii) housing wealth effects have increased for Asian countries in recent years; and (iv) consumption reacts stronger to negative than to positive shocks in housing and financial wealth.wealth effects, consumption, emerging markets.
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