When a DNA Triple helix melts: An analog of the Efimov state

The base sequences of DNA contain the genetic code and to decode it a double helical DNA has to open its base pairs. Recent studies have shown that one can use a third strand to identify the base sequences without opening the double helix but by forming a triple helix. It is predicted here that such a three chain system exhibits the unusual behaviour of the existence of a three chain bound state in the absence of any two being bound. This phenomenon is analogous to the Efimov state in three particle quantum mechanics. A scaling theory is used to justify the Efimov connection. Real space renormalization group (RG), and exact numerical calculations are used to validate the prediction of a biological Efimov effect.Comment: Replaced by the (almost) published version, except the word "curiouser

Growth patterns and scaling laws governing AIDS epidemic in Brazilian cities

Brazil holds approximately 1/3 of population living infected with AIDS (acquired immunodeficiency syndrome) in Central and South Americas, and it was also the first developing country to implement a large-scale control and intervention program against AIDS epidemic. In this scenario, we investigate the temporal evolution and current status of the AIDS epidemic in Brazil. Specifically, we analyze records of annual absolute frequency of cases for more than 5000 cities for the first 33 years of the infection in Brazil. We found that (i) the annual absolute frequencies exhibit a logistic-type growth with an exponential regime in the first few years of the AIDS spreading; (ii) the actual reproduction number decaying as a power law; (iii) the distribution of the annual absolute frequencies among cities decays with a power law behavior; (iv) the annual absolute frequencies and the number of inhabitants have an allometric relationship; (v) the temporal evolution of the annual absolute frequencies have different profile depending on the average annual absolute frequencies in the cities. These findings yield a general quantitative description of the AIDS infection dynamics in Brazil since the beginning. They also provide clues about the effectiveness of treatment and control programs against the infection, that has had a different impact depending on the number of inhabitants of cities. In this framework, our results give insights into the overall dynamics of AIDS epidemic, which may contribute to select empirically accurate models.Comment: 12 pages, 6 figure

On the consequences of the uncertainty principle on the superconducting fluctuations well inside the normal state

We first argue that the collective behaviour of the Cooper pairs created by thermal fluctuations well above the superconducting transition temperature, Tc, is dominated by the uncertainty principle which, in particular, leads to a well-defined temperature, T^C, above which the superconducting coherence vanishes. On the grounds of the BCS approach, the corresponding reduced-temperature, ln(T^C/Tc), is estimated to be around 0.55, i.e., above T^C \approx 1.7Tc coherent Cooper pairs cannot exist. The implications of these proposals on the superfluid density are then examined using the Gaussian-Ginzburg-Landau approximation. Then we present new measurements of the thermal fluctuation effects on the electrical conductivity and on the magnetization in different low- and high-Tc superconductors with different dopings which are in excellent agreement with these proposals and that demonstrate the universality of ln(T^C/Tc).Comment: LaTeX, 10 pages, 3 figures, as published in Europhysics Letter

Condensation of classical nonlinear waves

We study the formation of a large-scale coherent structure (a condensate) in classical wave equations by considering the defocusing nonlinear Schr\"odinger equation as a representative model. We formulate a thermodynamic description of the condensation process by using a wave turbulence theory with ultraviolet cut-off. In 3 dimensions the equilibrium state undergoes a phase transition for sufficiently low energy density, while no transition occurs in 2 dimensions, in analogy with standard Bose-Einstein condensation in quantum systems. Numerical simulations show that the thermodynamic limit is reached for systems with $16^3$ computational modes and greater. On the basis of a modified wave turbulence theory, we show that the nonlinear interaction makes the transition to condensation subcritical. The theory is in quantitative agreement with the simulations

Electromagnetic properties of the Delta(1232) and decuplet baryons in the self-consistent SU(3) chiral quark-soliton model

We examine the electromagnetic properties of the Delta(1232) resonance within the self-consistent chiral quark-soliton model. In particular we present the Delta form factors of the vector-current GE0, GE2 and GM1 for a momentum-transfer range of $Q^{2} \leq 1GeV^{2}$. We apply the symmetry-conserving quantization of the soliton and take 1/N_c rotational corrections into account. Values for the magnetic moments of all decuplet baryons as well as for the N-Delta transition are given. Special interest is also given to the electric quadrupole moment of the Delta.Comment: 24 pages, 8 figure

Energy Localization in the Peyrard-Bishop DNA model

We study energy localization on the oscillator-chain proposed by Peyrard and Bishop to model the DNA. We search numerically for conditions with initial energy in a small subgroup of consecutive oscillators of a finite chain and such that the oscillation amplitude is small outside this subgroup for a long timescale. We use a localization criterion based on the information entropy and we verify numerically that such localized excitations exist when the nonlinear dynamics of the subgroup oscillates with a frequency inside the reactive band of the linear chain. We predict a mimium value for the Morse parameter $(\mu >2.25)$ (the only parameter of our normalized model), in agreement with the numerical calculations (an estimate for the biological value is $\mu =6.3$). For supercritical masses, we use canonical perturbation theory to expand the frequencies of the subgroup and we calculate an energy threshold in agreement with the numerical calculations

Full Counting Statistics of Non-Commuting Variables: the Case of Spin Counts

We discuss the Full Counting Statistics of non-commuting variables with the measurement of successive spin counts in non-collinear directions taken as an example. We show that owing to an irreducible detector back-action, the FCS in this case may be sensitive to the dynamics of the detectors, and may differ from the predictions obtained with using a naive version of the Projection Postulate. We present here a general model of detector dynamics and path-integral approach to the evaluation of FCS. We concentrate further on a simple "diffusive" model of the detector dynamics where the FCS can be evaluated with transfer-matrix method. The resulting probability distribution of spin counts is characterized by anomalously large higher cumulants and substantially deviates from Gaussian Statistics.Comment: 11 pages, 3 figure

Three-dimensional Ginzburg-Landau simulation of a vortex line displaced by a zigzag of pinning spheres

A vortex line is shaped by a zigzag of pinning centers and we study here how far the stretched vortex line is able to follow this path. The pinning center is described by an insulating sphere of coherence length size such that in its surface the de Gennes boundary condition applies. We calculate the free energy density of this system in the framework of the Ginzburg-Landau theory and study the critical displacement beyond which the vortex line is detached from the pinning center.Comment: Submitted to special issue of Prammna-Journal of Physics devoted to the Vortex State Studie