Distribution of Interacting Ionic Particles in Disordered Media

Equilibrium distribution of interacting ionic particles in a charged disordered background is studied using the nonlinear Poisson-Boltzmann equation. For an arbitrarily given realization of the disorder, an exact solution of the equation is obtained in one dimension using a mapping of the nonlinear Poisson-Boltzmann equation to a self-consistent Schrodinger equation. The resulting density profile shows that the ions are delocalized, despite what the equivalent Schrodinger formulation in one dimension would suggest. It is shown that the ions are not distributed so as to locally neutralize the background, presumably due to their mutual interactions

Diabetes management: optimizing roles for nurses in insulin initiation

Type 2 diabetes is a major public health concern. Screening and early diagnosis followed by prompt and aggressive treatment interventions can help control progression of diabetes and its complications. Nurses are often the first healthcare team members to interact with patients and are being called on to apply their specialized knowledge, training, and skills to educate and motivate patients with diabetes about insulin use and practical ways to achieve treatment goals. Clinical nurse specialists possess specific training and skills to provide this level of care, while staff or office-based nurses may be trained by physicians to fulfill a task-specific role. This manuscript reviews the benefits of intensive glycemic control in type 2 diabetes, therapeutic goals and guidelines, advances in insulin therapy, and contribution of nurses in overcoming barriers to insulin initiation and related aspects of diabetes care. Nurses are particularly well positioned to fill the gap and improve efficiency in diabetes-related healthcare by assisting patients with insulin initiation and other aspects of glycemic self-management

Direct optical observations of surface thermal motions at sub-shot noise levels

We measure spectral properties of surface thermal fluctuations of liquids, solids, complex fluids and biological matter using light scattering methods. The random thermal fluctuations are delineated from random noise at sub-shot noise levels. The principle behind this extraction, which is quite general and is not limited to surface measurements, is explained. An optical lever is used to measure the spectrum of fluctuations in the inclinations of surfaces down to $\sim 10^{-17}\rm rad^2/Hz$ at $1\sim10 \mu$W optical intensity, corresponding to $\sim 10^{-29} \rm m^2/\rm Hz$ in the vertical displacement, in the frequency range $1{\rm}\rm kHz\sim10 MHz$. The dynamical evolution of the surface properties is also investigated. The measurement requires only a short amount of time and is essentially passive, so that it can be applied to a wide variety of surfaces.Comment: 5pp, 5 figure

Large Scale Structures a Gradient Lines: the case of the Trkal Flow

A specific asymptotic expansion at large Reynolds numbers (R)for the long wavelength perturbation of a non stationary anisotropic helical solution of the force less Navier-Stokes equations (Trkal solutions) is effectively constructed of the Beltrami type terms through multi scaling analysis. The asymptotic procedure is proved to be valid for one specific value of the scaling parameter,namely for the square root of the Reynolds number (R).As a result large scale structures arise as gradient lines of the energy determined by the initial conditions for two anisotropic Beltrami flows of the same helicity.The same intitial conditions determine the boundaries of the vortex-velocity tubes, containing both streamlines and vortex linesComment: 27 pages, 2 figure

Do Foreign Exchange Markets Still Trend?

Is it possible to profitably trade trends in foreign currencies? We examine the major currency futures contracts which have been trading since the 1970s as well as more recent contracts on exotic currencies that have only begun to trade in the past few years. The main conclusion is that the era of easy profits from simple trend following strategies in major foreign currencies is over. The markets have adapted to the extent that profits from these simple trading strategies have vanished.Presumably, trending may be a feature confined to currencies in the early years of a floating rate regime. When we look at some newly trading currencies, we see more attractive profit opportunities. Newly trading currency futures prices, like their counterparts thirty years ago, appear susceptible to trend following trading strategies

Numerical computation of isotropic Compton scattering

Compton scattering is involved in many astrophysical situations. It is well known and has been studied in detail for the past fifty years. Exact formulae for the different cross sections are often complex, and essentially asymptotic expressions have been used in the past. Numerical capabilities have now developed to a point where they enable the direct use of exact formulae in sophisticated codes that deal with all kinds of interactions in plasmas. Although the numerical computation of the Compton cross section is simple in principle, its practical evaluation is often prone to accuracy issues. These can be severe in some astrophysical situations but are often not addressed properly. In this paper we investigate numerical issues related to the computation of the Compton scattering contribution to the time evolution of interacting photon and particle populations. An exact form of the isotropic Compton cross section free of numerical cancellations is derived. Its accuracy is investigated and compared to other formulae. Then, several methods to solve the kinetic equations using this cross section are studied. The regimes where existing cross sections can be evaluated numerically are given. We find that the cross section derived here allows for accurate and fast numerical evaluation for any photon and electron energy. The most efficient way to solve the kinetic equations is a method combining a direct integration of the cross section over the photon and particle distributions and a Fokker-Planck approximation. Expressions describing this combination are given.Comment: 11 pages. Accepted for publication in A&

Dynamics of Counterion Condensation

Using a generalization of the Poisson-Boltzmann equation, dynamics of counterion condensation is studied. For a single charged plate in the presence of counterions, it is shown that the approach to equilibrium is diffusive. In the far from equilibrium case of a moving charged plate, a dynamical counterion condensation transition occurs at a critical velocity. The complex dynamic behavior of the counterion cloud is shown to lead to a novel nonlinear force-velocity relation for the moving plate.Comment: 5 pages, 1 ps figure included using eps

Nonlinear Dynamics of Capacitive Charging and Desalination by Porous Electrodes

The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by super-capacitors, water desalination and purification by capacitive deionization (or desalination), and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory in the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes with different time scales: (i) In the "super-capacitor regime" of small voltages and/or early times where the porous electrode acts like a transmission line, governed by a linear diffusion equation for the electrostatic potential, scaled to the RC time of a single pore. (ii) In the "desalination regime" of large voltages and long times, the porous electrode slowly adsorbs neutral salt, governed by coupled, nonlinear diffusion equations for the pore-averaged potential and salt concentration

The profile of a narrow line after single scattering by Maxwellian electrons: relativistic corrections to the kernel of the integral kinetic equation

The frequency distribution of photons in frequency that results from single Compton scattering of monochromatic radiation on thermal electrons is derived in the mildly relativistic limit. Algebraic expressions are given for (1) the photon redistribution function, K(nu,Omega -> nu',Omega'), and (2) the spectrum produced in the case of isotropic incident radiation, P(nu -> nu'). The former is a good approximation for electron temperatures kT_e < 25 keV and photon energies hnu < 50 keV, and the latter is applicable when hnu(hnu/m_ec^2) < kT_e < 25 keV, hnu < 50 keV. Both formulae can be used for describing the profiles of X-ray and low-frequency lines upon scattering in hot, optically thin plasmas, such as present in clusters of galaxies, in the coronae of accretion disks in X-ray binaries and AGNs, during supernova explosions, etc. Both formulae can also be employed as the kernels of the corresponding integral kinetic equations (direction-dependent and isotropic) in the general problem of Comptonization on thermal electrons. The K(nu,Omega -> nu',Omega') kernel, in particular, is applicable to the problem of induced Compton interaction of anisotropic low-frequency radiation of high brightness temperature with free electrons in the vicinity of powerful radiosources and masers. Fokker-Planck-type expansion (up to fourth order) of the integral kinetic equation with the P(nu -> nu') kernel derived here leads to a generalization of the Kompaneets equation. We further present (1) a simpler kernel that is necessary and sufficient to derive the Kompaneets equation and (2) an expression for the angular function for Compton scattering in a hot plasma, which includes temperature and photon energy corrections to the Rayleigh angular function.Comment: 29 pages, 17 figures, accepted for publication in ApJ, uses emulateapj.sty, corrects misprints in previous astro-ph versio

Statics and Dynamics of an Interface in a Temperature Gradient

The response and nonconserved dynamics of a two-phase interface in the presence of a temperature gradient oriented normally to the interface are considered. Two types of boundary conditions on the order parameter are considered, and the structure of the effective free energy and the Langevin equation for the collective coordinate specifying the interface position are analyzed.Comment: 15 pages, Revtex 3.0, 5 figures available upon reques