Transverse tunneling current through guanine traps in DNA

The current - voltage dependence of the transverse tunneling current through the electron or hole traps in a DNA is investigated. The hopping of the charge between the sites of the trap and the charge-phonon coupling results in a staircase structure of the I-V curve. For typical parameters of the DNA molecule the energy characteristics of a DNA trap can be extracted from the I-V dependence, viz., for a small gate voltage the phonon frequency and for a large gate voltage the hopping integral can be found from the positions of the steps in the I-V curve. Formation of the polaronic state also results in the redistribution of the tunneling current between the different sites of the traps

Mean-field theory for symmetry-breaking Fermi surface deformations on a square lattice

We analyze a mean-field model of electrons with pure forward scattering interactions on a square lattice which exhibits spontaneous Fermi surface symmetry breaking with a d-wave order parameter: the surface expands along the kx-axis and shrinks along the ky-axis (or vice versa). The symmetry-broken phase is stabilized below a dome-shaped transition line Tc(mu), with a maximal Tc near van Hove filling. The phase transition is usually first order at the edges of the transition line, and always second order around its center. The d-wave compressibility of the Fermi surface is however strongly enhanced even near the first order transition down to zero temperature. In the weak coupling limit the phase diagram is fully determined by a single non-universal energy scale, and hence dimensionless ratios of different characteristic quantities are universal. Adding a uniform repulsion to the forward scattering interaction, the two tricritical points at the ends of the second order transition line are shifted to lower temperatures. For a particularly favorable choice of hopping and interaction parameters one of the first order edges is replaced completely by a second order transition line, leading to a quantum critical point.Comment: 23 pages, 8 figure

Remodeling Of The Bone Tissue Of Rats Of Different Lines After Melatonin Effect

The markers of remodeling of bone tissue (BT) were studied after the impact of pharmacologic dose of melatonin (5 mg/kg of the animal body weight) during 28 days for 3-months rats-males of Wistar and SHR lines. The studies were carried out in autumn. The aim of our work was to study the indices of bone tissue remodeling of rats of Wistar and SHR lines after introduction of pharmacologic dose of exogenous melatonin.Biochemical and immune-enzyme methods of analysis were used in the study. In rats of Wistar line was revealed a reliable increase of activity of alkaline phosphatase (ALP) by 43,9% (Р<0,05), hyaluronidase activity (HA) by 15,4% and free thyroxin concentration (fТ4) by 30%. There was also registered the decrease of pyridinoline (PYD) concentration by 48% and glycosaminoglycan (GAG) by 46,7%. In rats of SHR line under the same conditions the results essentially differed. The activity of acid phosphatase (ACP) has a tendency to increase by 11,6%, and PYD concentration decreased by 25%. The concentrations of free triiodothyronine (fТ3) and fТ4 reliably increased by 51,3% and 31,1% respectively.In the result of research we revealed that melatonin plays the main role among several main factors of regulation of bone tissue remodeling. It has stimulating influence on bone tissue and hormones of thyroid gland

Phase switching in a voltage-biased Aharonov-Bohm interferometer

Recent experiment [Sigrist et al., Phys. Rev. Lett. {\bf 98}, 036805 (2007)] reported switches between 0 and $\pi$ in the phase of Aharonov-Bohm oscillations of the two-terminal differential conductance through a two-dot ring with increasing voltage bias. Using a simple model, where one of the dots contains multiple interacting levels, these findings are explained as a result of transport through the interferometer being dominated at different biases by quantum dot levels of different "parity" (i.e. the sign of the overlap integral between the dot state and the states in the leads). The redistribution of electron population between different levels with bias leads to the fact that the number of switching events is not necessarily equal to the number of dot levels, in agreement with experiment. For the same reason switching does not always imply that the parity of levels is strictly alternating. Lastly, it is demonstrated that the correlation between the first switching of the phase and the onset of the inelastic cotunneling, as well as the sharp (rather than gradual) change of phase when switching occurs, give reason to think that the present interpretation of the experiment is preferable to the one based on electrostatic AB effect.Comment: 12 pages, 9 figure

Image-Optimized Coronal Magnetic Field Models

We have reported previously on a new method we are developing for using image-based information to improve global coronal magnetic field models. In that work we presented early tests of the method which proved its capability to improve global models based on flawed synoptic magnetograms, given excellent constraints on the field in the model volume. In this follow-up paper we present the results of similar tests given field constraints of a nature that could realistically be obtained from quality white-light coronagraph images of the lower corona. We pay particular attention to difficulties associated with the line-of-sight projection of features outside of the assumed coronagraph image plane, and the effect on the outcome of the optimization of errors in localization of constraints. We find that substantial improvement in the model field can be achieved with this type of constraints, even when magnetic features in the images are located outside of the image plane