The DNA electronic specific heat at low temperature: The role of aperiodicity

AbstractThe electronic specific heat spectra at constant volume (CV) of a long-range correlated extended ladder model, mimicking a DNA molecule, is theoretically analyzed for a stacked array of a double-stranded structure made up from the nucleotides guanine G, adenine A, cytosine C and thymine T. The role of the aperiodicity on CV is discussed, considering two different nucleotide arrangements with increasing disorder, namely the Fibonacci and the Rudin–Shapiro quasiperiodic structures. Comparisons are made for different values of the band fillings, considering also a finite segment of natural DNA, as part of the human chromosome Ch22

An Improved Description of the Dielectric Breakdown in Oxides Based on a Generalized Weibull distribution

In this work, we address modal parameter fluctuations in statistical distributions describing charge-to-breakdown $(Q_{BD})$ and/or time-to-breakdown $(t_{BD})$ during the dielectric breakdown regime of ultra-thin oxides, which are of high interest for the advancement of electronic technology. We reobtain a generalized Weibull distribution ($q$-Weibull), which properly describes $(t_{BD})$ data when oxide thickness fluctuations are present, in order to improve reliability assessment of ultra-thin oxides by time-to-breakdown $(t_{BD})$ extrapolation and area scaling. The incorporation of fluctuations allows a physical interpretation of the $q$-Weibull distribution in connection with the Tsallis statistics. In support to our results, we analyze $t_{BD}$ data of SiO$_2$-based MOS devices obtained experimentally and theoretically through a percolation model, demonstrating an advantageous description of the dielectric breakdown by the $q$-Weibull distribution.Comment: 5 pages, 3 figure

On the Nature of the Phase Transition in SU(N), Sp(2) and E(7) Yang-Mills theory

We study the nature of the confinement phase transition in d=3+1 dimensions in various non-abelian gauge theories with the approach put forward in [1]. We compute an order-parameter potential associated with the Polyakov loop from the knowledge of full 2-point correlation functions. For SU(N) with N=3,...,12 and Sp(2) we find a first-order phase transition in agreement with general expectations. Moreover our study suggests that the phase transition in E(7) Yang-Mills theory also is of first order. We find that it is weaker than for SU(N). We show that this can be understood in terms of the eigenvalue distribution of the order parameter potential close to the phase transition.Comment: 15 page

Exciton trapping in a periodically modulated magnetic field

The behavior of excitons in spatially modulated magnetic fields is described taking into account theb exciton spin contribution. The results show that the exciton trapping in periodic magnetic fields is possible and dependent on the modulation profile

Transport In Photoexcited Hot Carriers Systems

The question of how the evolution of the nonequilibrium state of a highly photoexcited plasma in polar semiconductors (HEPS) affects the mobility of its hot carriers (photoinjected electrons and holes) is considered. General analytic expressions for the mobility, valid for a large class of experimental situations, are derived. That allows for an in depth analysis of transport properties of hot carriers in HEPS: It is demonstrated that, depending on initial conditions and experimental constraints, four different types of transient behavior may occur, namely, (i) structure (relative maxima and minima) without overshoot and a near ohmic regime in the steady state at low field intensities, (ii) structure with overshoot and non-ohmic regime in the steady state at intermediate field intensities, (iii) overshoot (no structure) and strongly non-ohmic regime at intermediate to high fields, and, (iv) normal (monotonicly increasing current) with ohmic behavior in the steady state at high fields. A general criterion for the existence of structure and/or overshoot during the mobility transient is established. Numerical calculations appropriate for electron transport in the central valley of GaAs are presented. © 1988.313-4497499Algarte, Luzzi, Time Evolution of Nonequilibrium Photoexcited Plasma in Polar Semiconductors (1983) Phys. Rev., 27 B, pp. 7563-7574Hammond, Electron-Velocity Overshoot Observed in an Impulse-Excited GaAs Semiconductor (1985) Physica, 134 B, pp. 475-479Luzzi, Vasconcellos, Relaxation Processes in Nonequilibrium Semiconductor plasma (1985) Semiconductors Probed by Ultrafast Laser Spectroscopy, 1, pp. 318-331. , R.R. Alfano, Academic, New York, Chap. 5Shank, Fork, Greene, Reinhard, Logan, Picosecond Nonequilibrium Carrier Transport in GaAs (1981) Appl. Phys. Lett., 38, pp. 104-105Zubarev, (1974) Nonequilibrium Statistical Thermodynamics, pp. 237-445. , Plenum, New York, Chap.