2,905 research outputs found
Wormholes and Child Universes
Evidence to the case that classical gravitation provides the clue to make
sense out of quantum gravity is presented. The key observation is the existence
in classical gravitation of child universe solutions or "almost" solutions,
"almost" because of some singularity problems. The difficulties of these child
universe solutions due to their generic singularity problems will be very
likely be cured by quantum effects, just like for example "almost" instanton
solutions are made relevant in gauge theories with breaking of conformal
invariance. Some well motivated modifcations of General Relativity where these
singularity problems are absent even at the classical level are discussed. High
energy density excitations, responsible for UV divergences in quantum field
theories, including quantum gravity, are likely to be the source of child
universes which carry them out of the original space time. This decoupling
could prevent these high UV excitations from having any influence on physical
amplitudes. Child universe production could therefore be responsible for UV
regularization in quantum field theories which take into account
semiclassically gravitational effects. Child universe production in the last
stages of black hole evaporation, the prediction of absence of tranplanckian
primordial perturbations, connection to the minimum length hypothesis and in
particular the connection to the maximal curvature hypothesis are discussed.
Some discussion of superexcited states in the case these states are Kaluza
Klein excitations is carried out. Finally, the posibility of obtaining "string
like" effects from the wormholes associated with the child universes is
discussed.Comment: Talk presented at the IWARA 2009 Conference, Maresias, Brazil,
October 2009, accepted for publication in the proceedings, World Scientific
format, 8 page
Child universes UV regularization?
It is argued that high energy density excitations, responsible for UV
divergences in quantum field theories, including quantum gravity, are likely to
be the source of child universes which carry them out of the original space
time. This decoupling prevents these high UV excitations from having any
influence on physical amplitudes. Child universe production could therefore be
responsible for UV regularization in quantum field theories which takes into
account gravitational effects. Also child universe production in the last
stages of black hole evaporation, the prediction of absence of tranplanckian
primordial perturbations, connection to the minimum length hypothesis and in
particular connection to the maximal curvature hypothesis are discussed.Comment: 6 pages, RevTex, discussion to the maximum curvature hypothesis adde
Second-layer nucleation in coherent Stranski-Krastanov growth of quantum dots
We have studied the monolayer-bilayer transformation in the case of the
coherent Stranski-Krastanov growth. We have found that the energy of formation
of a second layer nucleus is largest at the center of the first-layer island
and smallest on its corners. Thus nucleation is expected to take place at the
corners (or the edges) rather than at the center of the islands as in the case
of homoepitaxy. The critical nuclei have one atom in addition to a compact
shape, which is either a square of i*i or a rectangle of i*(i-1) atoms, with
i>1 an integer. When the edge of the initial monolayer island is much larger
than the critical nucleus size, the latter is always a rectangle plus an
additional atom, adsorbed at the longer edge, which gives rise to a new atomic
row in order to transform the rectangle into the equilibrium square shape.Comment: 6 pages, 4 figures. Accepted version, minor change
Unitary quantization and para-Fermi statistics of order two
A connection between a unitary quantization scheme and para-Fermi statistics
of order 2 is considered. An appropriate extension of Green's ansatz is
suggested. This extension allows one to transform bilinear and trilinear
commutation relations for the annihilation and creation operators of two
different para-Fermi fields and into identity. The way of
incorporating para-Grassmann numbers into a general scheme of
uniquantization is also offered. For parastatistics of order 2 a new fact is
revealed, namely, the trilinear relations containing both the para-Grassmann
variables and the field operators , under a certain
invertible mapping go over into the unitary equivalent relations, where
commutators are replaced by anticommutators and vice versa. It is shown that
the consequence of this circumstance is the existence of two alternative
definitions of the coherent state for para-Fermi oscillators. The Klein
transformation for Green's components of the operators , is
constructed in an explicit form that enables us to reduce the initial
commutation rules for the components to the normal commutation relations of
ordinary Fermi fields. A nontrivial connection between trilinear commutation
relations of the unitary quantization scheme and so-called Lie-supertriple
system is analysed. A brief discussion of the possibility of embedding the
Duffin-Kemmer-Petiau theory into the unitary quantization scheme is provided.Comment: 44 pages, the version published in J. Exp. Theor. Phy
Problem of the noise-noise correlation function in hot non-Abelian plasma
In this work on the basis of Kadomtsev's kinetic fluctuation theory we
present the more general expression for noise-noise correlation function in
effective theory for ultrasoft field modes.Comment: 3 pages, REVTeX
Influence of Intra-cell Traffic on the Output Power of Base Station in GSM
In this paper we analyze the influence of intracell traffic in a GSM cell on the base station output power. It is proved that intracell traffic increases this power. If offered traffic is small, the increase of output power is equal to the part of intracell traffic. When the offered traffic and, as the result, call loss increase, the increase of output power becomes less. The results of calculation are verified by the computer simulation of traffic process in the GSM cell. The calculation and the simulation consider the uniform distribution of mobile users in the cell, but the conclusions are of a general nature
Preparation of kombucha from winter savory (Satureja Montana L.) in the laboratory bioreactor
The possibility of obtaining kombucha from winter savory tea has been tested in the laboratory bioreactor by applying starter cultures and traditional way of inoculation. On the basis of the obtained results, it can be concluded that applying the inoculating method with the beverage from the previous process of biotransformation yielded kombucha beverage (capacity 15 I) from winter savory tea in the laboratory bioreactor. The application of defined starter culture from the isolate of yeast and acetic acid bacteria of local tea in the glass jar (capacity 5 I) gave 3 litres of kombucha beverage, which is acceptable according to the basic parameters and sensory characteristics. However, the application of the same starter culture in the laboratory bioreactor did not result in synchronized activity of yeast and bacteria
EPG-representations with small grid-size
In an EPG-representation of a graph each vertex is represented by a path
in the rectangular grid, and is an edge in if and only if the paths
representing an share a grid-edge. Requiring paths representing edges
to be x-monotone or, even stronger, both x- and y-monotone gives rise to three
natural variants of EPG-representations, one where edges have no monotonicity
requirements and two with the aforementioned monotonicity requirements. The
focus of this paper is understanding how small a grid can be achieved for such
EPG-representations with respect to various graph parameters.
We show that there are -edge graphs that require a grid of area
in any variant of EPG-representations. Similarly there are
pathwidth- graphs that require height and area in
any variant of EPG-representations. We prove a matching upper bound of
area for all pathwidth- graphs in the strongest model, the one where edges
are required to be both x- and y-monotone. Thus in this strongest model, the
result implies, for example, , and area bounds
for bounded pathwidth graphs, bounded treewidth graphs and all classes of
graphs that exclude a fixed minor, respectively. For the model with no
restrictions on the monotonicity of the edges, stronger results can be achieved
for some graph classes, for example an area bound for bounded treewidth
graphs and bound for graphs of bounded genus.Comment: Appears in the Proceedings of the 25th International Symposium on
Graph Drawing and Network Visualization (GD 2017
Field of homogeneous Plane in Quantum Electrodynamics
We study quantum electrodynamics coupled to the matter field on singular
background, which we call defect. For defect on the infinite plane we
calculated the fermion propagator and mean electromagnetic field. We show that
at large distances from the defect plane, the electromagnetic field is constant
what is in agreement with the classical results. The quantum corrections
determining the field near the plane are calculated in the leading order of
perturbation theory.Comment: 16 page
Synthesis and Optimization of Reversible Circuits - A Survey
Reversible logic circuits have been historically motivated by theoretical
research in low-power electronics as well as practical improvement of
bit-manipulation transforms in cryptography and computer graphics. Recently,
reversible circuits have attracted interest as components of quantum
algorithms, as well as in photonic and nano-computing technologies where some
switching devices offer no signal gain. Research in generating reversible logic
distinguishes between circuit synthesis, post-synthesis optimization, and
technology mapping. In this survey, we review algorithmic paradigms ---
search-based, cycle-based, transformation-based, and BDD-based --- as well as
specific algorithms for reversible synthesis, both exact and heuristic. We
conclude the survey by outlining key open challenges in synthesis of reversible
and quantum logic, as well as most common misconceptions.Comment: 34 pages, 15 figures, 2 table
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