1,086 research outputs found
Skyrmion on a three--cylinder
The class of static, spherically symmetric, and finite energy hedgehog
solutions in the SU(2) Skyrme model is examined on a metric three-cylinder. The
exact analytic shape function of the 1-Skyrmion is found. It can be expressed
via elliptic integrals. Its energy is calculated, and its stability with
respect to radial and spherically symmetric deformations is analyzed. No other
topologically nontrivial solutions belonging to this class are possible on the
three-cylinder.Comment: v2: version accepted for publication in Phys. Rev.
Niepełnoletni rodzice i ich rodziny jako podmiot wsparcia. Badania własne
Underage parenting is an experience that can be defined as difficult, even critical. It is the same both for teenagers and their families. Adopting the role of a father and mother in adolescence, and so prematurely, generates a number of difficulties that occur in almost every sphere of functioning of these young people. It is therefore necessary to take steps supporting not only underage parents, but also their families. In this article, the issue of supporting teen parents and their families have been described. The sources of information are the empirical studies of underage mothers carried out in 2008 and underage fathers in 2012-2013. They enabled not only to recognize the difficulties that usually involve teen parents, but also the scope and type of support they receive
Mutual Unbiasedness in Coarse-grained Continuous Variables
The notion of mutual unbiasedness for coarse-grained measurements of quantum
continuous variable systems is considered. It is shown that while the procedure
of "standard" coarse graining breaks the mutual unbiasedness between conjugate
variables, this desired feature can be theoretically established and
experimentally observed in periodic coarse graining. We illustrate our results
in an optics experiment implementing Fraunhofer diffraction through a periodic
diffraction grating, finding excellent agreement with the derived theory. Our
results are an important step in developing a formal connection between
discrete and continuous variable quantum mechanics.Comment: 5 pages, 3 figures + Supplemental Material (1 page) v2: Introduction
expanded, minor typos correcte
Coulomb matrix elements for the impact ionization process in nanocrystals: the envelope function approach
We propose a method for calculating Coulomb matrix elements between exciton
and biexciton states in semiconductor nanocrystals based on the envelope
function formalism. We show that such a calculation requires proper treatment
of the Bloch parts of the carrier wave functions which, in the leading order,
leads to spin selection rules identical to those holding for optical interband
transitions. Compared to the usual (intraband) Coulomb couplings, the resulting
matrix elements are additionally scaled by the ratio of the lattice constant to
the nanocrystal radius. As a result, the Coulomb coupling between exciton and
biexciton states scale as 1/R^2. We present also some statistical estimates of
the distribution of the coupling magnitudes and energies of the coupled states
The number of biexciton states coupled to exciton states form a certain energy
range shows a power-law scaling with the ratio of the coupling magnitude to the
energy separation. We estimate also the degree of mixing between exciton and
biexciton states. The amount of biexciton admixture to exciton states at least
1 eV above the multiple exciton generation threshold can reach 80% but varies
strongly with the nanocrystal size.Comment: 11 page
New Approaches to Minimum-Energy Design of Integer- and Fractional-Order Perfect Control Algorithms
In this paper the new methods concerning the energy-based minimization of the perfect control inputs is presented. For that reason the multivariable integer- and fractional-order models are applied which can be used for describing a various real world processes. Up to now, the classical approaches have been used in forms of minimum-norm/least squares inverses. Notwithstanding, the above-mentioned tool do not guarantee the optimal control corresponding to optimal input energy. Therefore the new class of inversebased methods has been introduced, in particular the new σ- and H-inverse of nonsquare parameter and polynomial matrices. Thus a proposed solution remarkably outperforms the typical ones in systems where the control runs can be understood in terms of different physical quantities, for example heat and mass transfer, electricity etc. A simulation study performed in Matlab/Simulink environment confirms the big potential of the new energy-based approaches
An algorithm for solving the pulsar equation
We present an algorithm of finding numerical solutions of pulsar equation.
The problem of finding the solutions was reduced to finding expansion
coefficients of the source term of the equation in a base of orthogo- nal
functions defined on the unit interval by minimizing a multi-variable mismatch
function defined on the light cylinder. We applied the algorithm to Scharlemann
& Wagoner boundary conditions by which a smooth solu- tion is reconstructed
that by construction passes success- fully the Gruzinov's test of the source
function exponent.Comment: 4 pages, 4 figures, accepted for publication in ApSS (a shortened
version of the previous one
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