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1.
The conformational changes of DNA in aqueous solutions containing ethanol and iso- and n-propanol having concentrations of 0–23 wt.% and ionic strength μ = 0.003 NaCl and exposed to γ radiation at doses from 0
Gy to 30 Gy were studied by low-gradient viscosimetry and circular dichroism. The dependence of the specific volume (V
sp) of DNA on the radiation dose changed at different contents of alcohol. There is a critical concentration (C
cr) at which the structure of the mixed solvent is rearranged. The V
sp of DNA decreased as the radiation dose increased at C
alc = 12 wt.% < C
cr and increased at C
alc = 23 wt.% > C
cr. In both cases, the largest V
sp of DNA was observed in water ethanol solutions. The secondary structure of the macromolecule in the systems corresponds to
the form. It was shown that the observed conformational changes in irradiated DNA at C
alc < C
cr and C
alc > C
cr could not be explained only by the ability of alcohols to intercept the radicals formed in radiolysis of water. 相似文献
2.
With the aim of a further investigation of the nonperturbative Hamiltonian approach in gauge field theories, the mass spectrum of QED-2 is calculated numerically by using the corrected Hamiltonian that was constructed previously for this theory on the light front. The calculations are performed for a wide range of the ratio of the fermion mass to the fermion charge at all values of the parameter \(\hat \theta \) related to the vacuum angle θ. The results obtained in this way are compared with the results of known numerical calculations on a lattice in Lorentz coordinates. A method is proposed for extrapolating the values obtained within the infrared-regularized theory to the limit where the regularization is removed. The resulting spectrum agrees well with the known results in the case of θ = 0; in the case of θ = π, there is agreement at small values of the fermionmass (below the phase-transition point). 相似文献
3.
Paston S. A. Prokhvatilov E. V. Franke V. A. 《Theoretical and Mathematical Physics》2004,139(3):807-822
We briefly describe problems of the Hamiltonian approach for quantizing gauge fields on the light front for space–time bounded by the inequality |x
–|L with periodic boundary conditions in the variable x
– imposed on all fields (the DLCQ method). With these restrictions, we consider the gauge-invariant ultraviolet regularization by passing to a lattice in transverse coordinates. We remove the remaining ultraviolet divergences in the longitudinal momentum p
– by imposing a gauge-invariant finite-mode regularization. It turns out that the canonical formalism on the light front with such a regularization imposed does not contain the usual most complicated second-class constraints between zero and nonzero modes of fields. The described scheme can be used both to regularize the standard gauge theory and to provide a gauge-invariant formulation of effective low-energy models on the light front. Because the manifest Lorentz invariance is broken in our formalism, the vacuum state is poorly defined. We discuss this problem, in particular, in relation to the problem of passing to the continuous space limit. 相似文献
4.
S. A. Paston E. V. Prokhvatilov V. A. Franke 《Theoretical and Mathematical Physics》1999,120(3):1164-1181
We propose the light-front Lagrangian and the corresponding Hamiltonian that produce a theory perturbatively equivalent to
the conventional QCD in the Lorentz coordinates after the regularization is removed. The regularization used is nonstandard
and breaks the gauge invariance.But after the regularization is removed, this invariance is restored by the introduction of
a finite number of counterterms with coefficients dependent on the regularization parameters.
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 120, No. 3, pp. 417–437, September, 1999. 相似文献
5.
We consider the formulation of the gravity theory first suggested by Regge and Teitelboim where the space-time is a four-dimensional
surface in a flat ten-dimensional space. We investigate a canonical formalism for this theory following the approach suggested
by Regge and Teitelboim. Under constructing the canonical formalism we impose additional constraints agreed with the equations
of motion. We obtain the exact form of the first-class constraint algebra. We show that this algebra contains four constraints
which form a subalgebra (the ideal), and if these constraints are fulfilled, the algebra becomes the constraint algebra of
the Arnowitt-Deser-Misner formalism of Einstein’s gravity. The reasons for the existence of additional first-class constraints
in the canonical formalism are discussed. 相似文献
6.
Theoretical and Mathematical Physics - We consider the dimer model on a hexagonal lattice. This model can be represented as a “pile of cubes in a box.” The energy of a configuration is... 相似文献
7.
Theory of gravity is considered in the Regge–Teitelboim approach in which the pseudo-Rimannian space is treated as a surface isometrically embedded in an ambient Minkowski space of higher dimension. This approach is formulated in terms of a field theory in which the original pseudo-Rimannian space is defined by the field constant-value surfaces. The symmetry properties of the proposed theory are investigated, and possible structure of the field-theoretical Lagrangian is discussed. 相似文献
8.
Ershov D. S. Paston S. V. Kartsova L. A. Alekseeva A. V. Ganzha O. V. Kasyanenko N. A. 《Structural chemistry》2011,22(2):475-482
The influence of tea and coffee flavonoids (−)-epicatechin (EC) and (+)-catechin (C) on the effect of γ-irradiation of DNA
molecules in solutions was investigated. The concentrations of these and other components in different samples of black and
green tea were analyzed by the capillary electrophoresis. It was determined from the experimental data obtained by different
methods (circular dichroism and UV spectra, viscosimetry and optical investigations) that C and EC do not form complexes with
DNA in solutions. It was shown that C and EC have radioprotective properties, being scavengers of the water radiolysis products. 相似文献
9.
We study the approach in which independent variables describing gravity are functions of the space-time embedding into a flat
space of higher dimension. We formulate a canonical formalism for such a theory in a form that requires imposing additional
constraints, which are a part of Einstein’s equations. As a result, we obtain a theory with an eight-parameter gauge symmetry.
This theory becomes equivalent to Einstein’s general relativity either after partial gauge fixing or after rewriting the metric
in the form that is invariant under the additional gauge transformations. We write the action for such a theory.
__________
Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 153, No. 2, pp. 271–288, November, 2007. 相似文献
10.
Paston S. A. Prokhvatilov E. V. Franke V. A. 《Theoretical and Mathematical Physics》2002,131(1):516-526
A light-front Hamiltonian reproducing the results of two-dimensional quantum electrodynamics in the Lorentz coordinates is constructed using the bosonization procedure and an analysis of the bosonic perturbation theory in all orders in the fermion mass. The resulting Hamiltonian involves a supplementary counterterm in addition to the usual terms appearing in the naive light-front quantization. This term is proportional to a linear combination of zeroth fermion modes (which are multiplied by a factor compensating the charge and fermion number). The coefficient of the counterterm has no ultraviolet divergence, depends on the value of the fermion condensate in the -vacuum, and is linear in this value for a small fermion mass. 相似文献