1,515 research outputs found
Probability Theory Compatible with the New Conception of Modern Thermodynamics. Economics and Crisis of Debts
We show that G\"odel's negative results concerning arithmetic, which date
back to the 1930s, and the ancient "sand pile" paradox (known also as "sorites
paradox") pose the questions of the use of fuzzy sets and of the effect of a
measuring device on the experiment. The consideration of these facts led, in
thermodynamics, to a new one-parameter family of ideal gases. In turn, this
leads to a new approach to probability theory (including the new notion of
independent events). As applied to economics, this gives the correction, based
on Friedman's rule, to Irving Fisher's "Main Law of Economics" and enables us
to consider the theory of debt crisis.Comment: 48p., 14 figs., 82 refs.; more precise mathematical explanations are
added. arXiv admin note: significant text overlap with arXiv:1111.610
Syntactic Complexity of R- and J-Trivial Regular Languages
The syntactic complexity of a regular language is the cardinality of its
syntactic semigroup. The syntactic complexity of a subclass of the class of
regular languages is the maximal syntactic complexity of languages in that
class, taken as a function of the state complexity n of these languages. We
study the syntactic complexity of R- and J-trivial regular languages, and prove
that n! and floor of [e(n-1)!] are tight upper bounds for these languages,
respectively. We also prove that 2^{n-1} is the tight upper bound on the state
complexity of reversal of J-trivial regular languages.Comment: 17 pages, 5 figures, 1 tabl
Initial Conditions for Semiclassical Field Theory
Semiclassical approximation based on extracting a c-number classical
component from quantum field is widely used in the quantum field theory.
Semiclassical states are considered then as Gaussian wave packets in the
functional Schrodinger representation and as Gaussian vectors in the Fock
representation. We consider the problem of divergences and renormalization in
the semiclassical field theory in the Hamiltonian formulation. Although
divergences in quantum field theory are usually associated with loop Feynman
graphs, divergences in the Hamiltonian approach may arise even at the tree
level. For example, formally calculated probability of pair creation in the
leading order of the semiclassical expansion may be divergent. This observation
was interpretted as an argumentation for considering non-unitary evolution
transformations, as well as non-equivalent representations of canonical
commutation relations at different time moments. However, we show that this
difficulty can be overcomed without the assumption about non-unitary evolution.
We consider first the Schrodinger equation for the regularized field theory
with ultraviolet and infrared cutoffs. We study the problem of making a limit
to the local theory. To consider such a limit, one should impose not only the
requirement on the counterterms entering to the quantum Hamiltonian but also
the requirement on the initial state in the theory with cutoffs. We find such a
requirement in the leading order of the semiclassical expansion and show that
it is invariant under time evolution. This requirement is also presented as a
condition on the quadratic form entering to the Gaussian state.Comment: 20 pages, Plain TeX, one postscript figur
Techniques for the Synthesis of Reversible Toffoli Networks
This paper presents novel techniques for the synthesis of reversible networks
of Toffoli gates, as well as improvements to previous methods. Gate count and
technology oriented cost metrics are used. Our synthesis techniques are
independent of the cost metrics. Two new iterative synthesis procedure
employing Reed-Muller spectra are introduced and shown to complement earlier
synthesis approaches. The template simplification suggested in earlier work is
enhanced through introduction of a faster and more efficient template
application algorithm, updated (shorter) classification of the templates, and
presentation of the new templates of sizes 7 and 9. A novel ``resynthesis''
approach is introduced wherein a sequence of gates is chosen from a network,
and the reversible specification it realizes is resynthesized as an independent
problem in hopes of reducing the network cost. Empirical results are presented
to show that the methods are effective both in terms of the realization of all
3x3 reversible functions and larger reversible benchmark specifications.Comment: 20 pages, 5 figure
PROBLEM OF HEART SALVATION DURING REPERFUSION. OPIOID RECEPTOR AGONISTS AS A POSSIBLE SOLUTION
Ischaemia/reperfusion cardiac injury contributes to morbidity and mortality during percutaneous coronary intervention, heart surgery and transplantation. Even when the recanalization of an infarct-related coronary artery is carried out successfully, there is still a risk of death due to reperfusion injury. Numerous pharmacological interventions have been found in experiments on animals. However, the translation of these interventions to clinical practice has been disappointing. None of the drug treatment has been able to improve in-hospital mortality of patients with acute myocardial infarction. The search for pharmacological agents able to salvage myocardium during reperfusion continues. Opioid receptor (OR) agonists represent one of the promising group of drugs for treatment of patients with myocardial infarction. It has been found that µ-, δ- and κ-OR agonists are able to attenuate heart injury when administered before or at the beginning of reperfusion. However, what kind of OR receptors need to be activated in order to protect the heart during reperfusion and the precise mechanism of this effect have yet to be elucidated.Ischaemia/reperfusion cardiac injury contributes to morbidity and mortality during percutaneous coronary intervention, heart surgery and transplantation. Even when the recanalization of an infarct-related coronary artery is carried out successfully, there is still a risk of death due to reperfusion injury. Numerous pharmacological interventions have been found in experiments on animals. However, the translation of these interventions to clinical practice has been disappointing. None of the drug treatment has been able to improve in-hospital mortality of patients with acute myocardial infarction. The search for pharmacological agents able to salvage myocardium during reperfusion continues. Opioid receptor (OR) agonists represent one of the promising group of drugs for treatment of patients with myocardial infarction. It has been found that µ-, δ- and κ-OR agonists are able to attenuate heart injury when administered before or at the beginning of reperfusion. However, what kind of OR receptors need to be activated in order to protect the heart during reperfusion and the precise mechanism of this effect have yet to be elucidated
Nonlinear dynamics of soft fermion excitations in hot QCD plasma III: Soft-quark bremsstrahlung and energy losses
In general line with our early works [Yu.A. Markov, M.A. Markova, Nucl. Phys.
A770 (2006) 162; 784 (2007) 443] within the framework of a semiclassical
approximation the general theory of calculation of effective currents and
sources generating bremsstrahlung of an arbitrary number of soft quarks and
soft gluons at collision of a high-energy color-charged particle with thermal
partons in a hot quark-gluon plasma, is developed. For the case of one- and
two-scattering thermal partons with radiation of one or two soft excitations,
the effective currents and sources are calculated in an explicit form. In the
model case of `frozen' medium, approximate expressions for energy losses
induced by the most simple processes of bremsstrahlung of soft quark and soft
gluon, are derived. On the basis of a conception of the mutual cancellation of
singularities in the sum of so-called `diagonal' and `off-diagonal'
contributions to the energy losses, an effective method of determining color
factors in scattering probabilities, containing the initial values of Grassmann
color charges, is suggested. The dynamical equations for Grassmann color
charges of hard particle used by us early are proved to be insufficient for
investigation of the higher radiative processes. It is shown that for correct
description of these processes the given equations should be supplemented
successively with the higher-order terms in powers of the soft fermionic field.Comment: 93 pages, 20 figure
First-Matsubara-frequency rule in a Fermi liquid. Part II: Optical conductivity and comparison to experiment
Motivated by recent optical measurements on a number of strongly correlated
electron systems, we revisit the dependence of the conductivity of a Fermi
liquid, \sigma(\Omega,T), on the frequency \Omega and temperature T. Using the
Kubo formalism and taking full account of vertex corrections, we show that the
Fermi liquid form Re\sigma^{-1}(\Omega,T)\propto \Omega^2+4\pi^2T^2 holds under
very general conditions, namely in any dimensionality above one, for a Fermi
surface of an arbitrary shape (but away from nesting and van Hove
singularities), and to any order in the electron-electron interaction. We also
show that the scaling form of Re\sigma^{-1}(\Omega,T) is determined by the
analytic properties of the conductivity along the Matsubara axis. If a system
contains not only itinerant electrons but also localized degrees of freedom
which scatter electrons elastically, e.g., magnetic moments or resonant levels,
the scaling form changes to Re\sigma^{-1}(\Omega,T)\propto \Omega^2+b\pi^2T^2,
with 1\leq b<\infty. For purely elastic scattering, b =1. Our analysis implies
that the value of b\approx 1, reported for URu_2Si_2 and some rare-earth based
doped Mott insulators, indicates that the optical conductivity in these
materials is controlled by an elastic scattering mechanism, whereas the values
of b\approx 2.3 and b\approx 5.6, reported for underdoped cuprates and
organics, correspondingly, imply that both elastic and inelastic mechanisms
contribute to the optical conductivity.Comment: 18 pages, 10 figure
Comments on the Sign and Other Aspects of Semiclassical Casimir Energies
The Casimir energy of a massless scalar field is semiclassically given by
contributions due to classical periodic rays. The required subtractions in the
spectral density are determined explicitly. The so defined semiclassical
Casimir energy coincides with that obtained using zeta function regularization
in the cases studied. Poles in the analytic continuation of zeta function
regularization are related to non-universal subtractions in the spectral
density. The sign of the Casimir energy of a scalar field on a smooth manifold
is estimated by the sign of the contribution due to the shortest periodic rays
only. Demanding continuity of the Casimir energy under small deformations of
the manifold, the method is extended to integrable systems. The Casimir energy
of a massless scalar field on a manifold with boundaries includes contributions
due to periodic rays that lie entirely within the boundaries. These
contributions in general depend on the boundary conditions. Although the
Casimir energy due to a massless scalar field may be sensitive to the physical
dimensions of manifolds with boundary, its sign can in favorable cases be
inferred without explicit calculation of the Casimir energy.Comment: 39 pages, no figures, references added, some correction
Mathematical Conception of "Phenomenological" Equilibrium Thermodynamics
In the paper, the principal aspects of the mathematical theory of equilibrium
thermodynamics are distinguished. It is proved that the points of degeneration
of a Bose gas of fractal dimension in the momentum space coincide with critical
points or real gases, whereas the jumps of critical indices and the Maxwell
rule are related to the tunnel generalization of thermodynamics. Semiclassical
methods are considered for the tunnel generalization of thermodynamics and also
for the second and ultrasecond quantization (operators of creation and
annihilation of pairs). To every pure gas there corresponds a new critical
point of the limit negative pressure below which the liquid passes to a
dispersed state (a foam). Relations for critical points of a homogeneous
mixture of pure gases are given in dependence on the concentration of gases.Comment: 37 pages, 9 figure, more precise explanations, more references. arXiv
admin note: substantial text overlap with arXiv:1202.525
Linear superposition in nonlinear wave dynamics
We study nonlinear dispersive wave systems described by hyperbolic PDE's in
R^{d} and difference equations on the lattice Z^{d}. The systems involve two
small parameters: one is the ratio of the slow and the fast time scales, and
another one is the ratio of the small and the large space scales. We show that
a wide class of such systems, including nonlinear Schrodinger and Maxwell
equations, Fermi-Pasta-Ulam model and many other not completely integrable
systems, satisfy a superposition principle. The principle essentially states
that if a nonlinear evolution of a wave starts initially as a sum of generic
wavepackets (defined as almost monochromatic waves), then this wave with a high
accuracy remains a sum of separate wavepacket waves undergoing independent
nonlinear evolution. The time intervals for which the evolution is considered
are long enough to observe fully developed nonlinear phenomena for involved
wavepackets. In particular, our approach provides a simple justification for
numerically observed effect of almost non-interaction of solitons passing
through each other without any recourse to the complete integrability. Our
analysis does not rely on any ansatz or common asymptotic expansions with
respect to the two small parameters but it uses rather explicit and
constructive representation for solutions as functions of the initial data in
the form of functional analytic series.Comment: New introduction written, style changed, references added and typos
correcte
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