27,677 research outputs found
From surface to random criticality in layered planar Ising models
A general case of a spatially nonuniform planar layered Ising model, or an
equivalent quantum Ising chain, is analysed with an exact functional real space
renormalization group. Various surface, finite size, quasiperiodic and random
layer (McCoy-Wu) universality classes are obtained and discussed within a
single theoretical framework leading to new insights into the nature of random
criticality.Comment: 11 pages; REVTeX 3.
Statistics of branched flow in a weak correlated random potential
Recent images of electron flow through a two-dimensional electron gas (2DEG)
device show branching behavior that is reproduced in numerical simulations of
motion in a correlated random potential [cond-mat/0010348]. We show how such
branching naturally arises from caustics in the classical flow and find a
simple scaling behavior of the branching under variation of the random
potential strength. Analytic results describing the statistical properties of
the branching are confirmed by classical and quantum numerical tests.Comment: 4 pages, 4 figure
Defending Time-Symmetrized Quantum Theory
Recently, several authors have criticized time-symmetrized quantum theory
originated by the work of Aharonov et al. (1964). The core of this criticism
was the proof, which appeared in various forms, showing that counterfactual
interpretation of time-symmetrized quantum theory cannot be reconciled with the
standard quantum theory. I argue here that the apparent contradiction appears
due to inappropriate usage of traditional time asymmetric approach to
counterfactuals, and that the contradiction disappears when the problem is
analyzed in terms of time-symmetric counterfactuals. I analyze various aspects
of time-symmetry of quantum theory and defend the time-symmetrized formalism.Comment: 19 pages, LaTe
About Algorithm for Transformation of Logic Functions (ATLF)
In this article the algorithm for transformation of logic functions which are
given by truth tables is considered. The suggested algorithm allows the
transformation of many-valued logic functions with the required number of
variables and can be looked in this sense as universal.Comment: 25 pages, in English, German and Russia
A New Approach to Understanding Ontogenesis and The Theory of Aging
This paper proposes an original theory of aging of multicellular organisms.
The cells of multicellular organisms, in contrast to unicellular organisms, are
burdened with a two- part genome: housekeeping and specialized (multicellular),
responsible for ontogenesis and terminal differentiation. The two parts of the
genome compete for limited adaptive resources thereby interfering with the
ability of the house-keeping part of the genome to adequately perform
reparative and adaptive functions in post mitotic cells. The necessity to
complete the ontgenesis program, leads to increased activity of the
multicellular components of the genome. As a result, the allocation of cellular
resources to specialized genome con-tinuously increases with time. This leads
to a deficit of reparative and adaptive capacity in post mitotic cells.
Suggestions for future research focus on identifying groups of genes
responsible for regulation of growth rate of specialized genome and suppressing
ability of the cell division. A better understanding of the relationship
between the two parts of the genome will not only help us to manipulate
ontogenesis and aging, but will also improve our understanding of cancer
development and ontogenesis.Comment: 16 pages, 1 figure, 82 ref; Keywords: Aging, Ontogenesis, Genom
Probability and the Many-Worlds Interpretation of Quantum Theory
Two works related to the concept of probability in the framework of the
many-worlds interpretation are presented. The first deals with recent
controversy in classical probability theory. Elga and D. Lewis argues that
Sleeping Beauty should have different credences for the result of a fair coin
toss in a particular situation. It is argued that when the coin is replaced by
a quantum coin, the credence is unambiguous and since one should not expect a
difference between classical and quantum coins, this provides a particular
resolution of the controversy. Second work is an analysis of a recent criticism
by Byrne and Hall of Everett-type approach presented by Chalmers. It is shown
that the criticism has no universal validity and that the Byrne and Hall
rejection of any Everett-type interpretation of quantum mechanics is unfounded.Comment: 15 pages. Contribution to the conference: Reconsideration of
Foundations of Quantum Mechanics, Sweeden 2001. Section 3 has overlap with
quant-ph/000105
Tachyonic Preheating
I review the theory of preheating after inflation, focusing on the recently
found tachyonic preheating in the theories with spontaneous symmetry breaking.
This occurs due to the tachyonic instability of the scalar field near the top
of its effective potential. Contrary to the common expectation, tachyonic
instability converts most of the energy into that of colliding classical waves
very rapidly, within a single oscillation. Efficient tachyonic preheating is
typical for the hybrid inflationary scenario, including SUSY motivated and
brane inflation models.Comment: 18 pages, contribution to the Proceedings of PASCOS 200
Almost commuting matrices with respect to normalized Hilbert-Schmidt norm
Almost-commuting matrices with respect to the normalized Hilbert-Schmidt norm
are considered. Normal almost commuting matrices are proved to be near
commuting.Comment: 11 page
Elementary Particles in a Quantum Theory Over a Galois Field
We consider elementary particles in a quantum theory based on a Galois field.
In this approach infinities cannot exist, the cosmological constant problem
does not arise and one irreducible representation of the symmetry algebra
necessarily describes a particle and its antiparticle simultaneously. {\it In
other words, the very existence of antiparticles is a strong indication that
nature is described rather by a finite field (or at least a field with a
nonzero characteristic) than by complex numbers.} As a consequence, the
spin-statistics theorem is simply a requirement that standard quantum theory
should be based on complex numbers and elementary particles cannot be neutral.
The Dirac vacuum energy problem has a natural solution and the vacuum energy
(which in the standard theory is infinite and negative) equals zero as it
should be.Comment: Latex, 37 pages, no figures. Minor changes in motivation. In
particular, it is noted that the very existence of antiparticles is a strong
indication that nature is described rather by a finite field (or at least a
field with a nonzero characteristic) than by complex number
Characterization of sofic groups and equations over groups
We give the following characterization of sofic (weakly sofic) groups: a
group is sofic (weakly sofic) if and only if any system of equations
solvable in any alternating group (any finite group) is solvable over .Comment: This paper has been withdrawn by the author due to all its results
are in 1506.06940. The paper 1506.06940 contains more general and clearly
written result
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