Inverse Strength Research Articles

Apparent persistence lengths and diffusion behavior of high molecular weight hyaluronate

AbstractHigh purity, high molecular weight hyaluronate from bacteria and rooster comb exhibited clear polyelectrolyte properties, as observed by static and dynamic light scattering. The scattered intensity of hyaluronate solutions increased markedly with ionic strength, while the radii of gyration decreased. Apparent persistence lengths within the wormlike chain model in the coil limit were estimated as a function of ionic strength. The total apparent persistence length varied from about 87 Å in the high ionic strength limit to nearly 400 Å at 1 mM added NaCl. The apparent electrostatic persistence length varied approximately as the inverse square root of the ionic strength. Deviations from the theoretically predicted inverse ionic strength dependence were investigated in terms of excluded volume effects. Dynamic light scattering yielded “ordinary phase” diffusion coefficients whose dependence on polymer and salt concentration agreed reasonably well with hydrodynamic coupled mode theory in the linear limit. Extrapolations to infinite polymer dilution at fixed salts yielded, surprisingly, a constant diffusion coefficient. Thus, there was no evidence of either polyion expansion or electrolyte friction effects in the infinite dilution diffusion coefficients. Since clear evidence for polyion expansion was seen in the static scattering, it is thought that the relative stiffness and consequent openness of the hyaluronate coils lead to partial free draining behavior. There was no evidence for an “extraordinary phase” under no added salt and low added salt conditions. The overall results are contrasted with the very different behavior previously reported for medium purity hyaluronate from animal sources.

Unusual maps and their use to approach usual ones

One-dimensional maps coupled to discrete valued variables are introduced. They are designed to describe the motion in Lorenz and Henon type systems on branched manifolds arising by expanding the maps in powers of the inverse dissipation strength, or by coarse graining. The maps are studied in detail along the crisis line where they exhibit complex behaviour with periodic and chaotic attractors. The convergence to the Henon map is investigated numerically and found to be satisfactory for not too weak dissipations.

Nonlinear elimination of magnetoresistance divergences due to Landau quantization

We discuss here the role of nonlinearity in an isothermal balance equation transport theory in eliminating the divergence associated with Landau quantization which occurs in linear theories for impurity-limited transverse magnetoresistance. This nonlinear mechanism for elimination of the divergence is shown to be effective with or without shielding, although shielding does influence the detailed quantitative results. Explicit calculations of the finite magnetoresistance below the degeneracy temperature are carried out here, including the role of dynamic descreening phenomena, and nonlinear oscillatory behavior as a function of drift velocity and as a function of inverse magnetic field strength is exhibited.

Regions and Boundaries for Diffracting Shock Wave Systems

AbstractThis paper examines, as completely as possible, the wave systems that may occur when a plane shock wave i diffracts over a concave corner. For a perfect gas, a particular wave system is specified by three parameters (γ, ϵi, ωo), which are respectively the ratio of the specific heats γ, the inverse strength ϵi of i, and its angle of incidence ωo. The topology of the (ϵi, ωo) plane is studied for a given γ (gas), and regions or domains corresponding to each wave system are delineated. Exact expressions are given for the boundaries of many of these regions. Although it is plausible that the boundaries represent the transition conditions between the wave systems, a detailed analysis shows that the situation is sometimes more complicated than might be expected. A new transition criterion, which may be valid for diffraction over flexible surfaces, is presented. For very weak shocks (ϵi > 0.8328 in air), it is found that Mach reflexion cannot exist, and in its place a continuous wave system is indicated.

Production of light pseudoscalar particles in heavy-ion collisions.

We calculate the cross section for the production of a hypothetical light neutral pseudoscalar particle in heavy-ion collisions due to the two-photon process. For an inverse coupling strength f in the 100-GeV range we predict a cross section of ${10}^{\mathrm{\ensuremath{-}}14}$ ${\mathrm{fm}}^{2}$ for production of a particle with 1.5-MeV mass. For the maximal allowed coupling f=5 MeV and an effective reduction of the particle mass due to binding the cross section may reach in to the \ensuremath{\mu}b range.

Systematic Bivariate Analysis of AM Field Strength Measurement Data

A systematic method for analyzing AM field strength measurement data to establish inverse distance field strength and ground conductivity zones is presented. The technique uses a simple bivariate error minimization routine to find the combination of radiation and conductivity which most closely matches the measurement data out to three kilometers. The balance of the conductivity zones are determined by a running average which again seeks minimum error when compared to digitized versions of the FCC groundwave propagation curves. An extension of the technique allows such net conductivities along a radial to be converted to equivalent M3 map conductivities. The mathematical algorithms provide unique and repeatable results, and are readily adapted for use in computer programs.

Interaction of Corona with Dielectric Material Until Damage

A study of polyethylene terephthalate (PET) and polypropylene (PP) treated by corona discharge for a short time is presented. Different techniques of analysis such as inverse chromatography, infrared spectroscopy, loss tangent and electric strength were used. Working at 50 Hz with a gap of 2 mm and different gases, the analysis of the polymer after treatment has shown that a limit in the transformation of the surface may be considered. Thus a critical time is defined between a pure transformation and a degradation. This latter phase is also studied with a cross linked polyethylene (XLPE). The infrared analysis and electric strength measurements have shown the role played by the relative humidity present in air.

Shock waves at a slow-fast gas interface

This paper describes the results of our experiments with shock waves refracting at a CO2/CH4 interface. The refraction is slow-fast because the speed of sound in the incident gas (CO2) is less than that in the transmitting gas (CH4). We found three phenomena which apparently have not been reported before and which all have free precursor shocks in their wave systems; schlieren photographs of them are presented. As a result of the present and earlier work, we can assert that there exist at least four different free precursor refractions. Theoretical studies suggest that the slow-fast phenomena can be conveniently classified into three groups characterized by different ranges of values of the inverse strength ζi of the incident shock i. The classification may be an exhaustive list of the phenomena, at least when the gases are nearly perfect, but we cannot be sure. We present experimental data on all the phenomena in each group, including data on the transition conditions from one wave system to another both within and across the groups.

Nonisothermal band model theory

Theoretical formulations of radiation band models for general nonuniform optical paths are presented. The models are framed within the statistical band model for an array of Lorentz lines and an inverse line strength distribution. Radiative transfer for an isolated line in a general nonuniform medium and the statistical model for a uniform optical path are reviewed in order to provide the foundation required for the band model formulations. Two approaches to the development of these models are taken. The first is based on making approximations to such radiative transfer functions as transmittance or equivalent width and yields models equivalent or similar to the traditional Curtis-Godson approximation. The second treats approximations to the spatial derivatives of these functions. From the standpoint of computing line or band radiance, the spatial derivatives are more fundamental quantities than the transfer functions themselves; consequently, these latter “derivative approximations” are instrinsically more accurate than the Curtis-Godson type approximations. All of the models are formulated to give the spatial derivative of the mean equivalent width function W ̄ (s) δ in the form 1 δ d W ̄ (s) ds =c(s)p(s) k ̄ (s)y(s) , where c( s), p( s) and k̄( s) are the concentration, total pressure and absorption band model parameter, respectively, at the local path position s. The functional form of the derivative function y( s) is derived for each of the models. In general, y( s) is a function of both local and path-averaged (subscript e) band model parameters. These local and averaged parameters are used to define a dimensionless optical depth parameter x e = u k ̄ e β e and three nonuniformity indexes ρ= γ ̄ γ ̄ e , r= β β e and θ = δ ̄ e δ ̄ (γ̄ is line width, ḡd is the mean line spacing band model parameter, and β = 2μ γ ̄ γ ̄ ). The explicit manner in which these parameters enter into the various functional forms for y( s) is derived and discussed. The introduction of the parameter q is an important aspect of the new models and is an explicit measure of nonisothermality along the optical path. In addition to the traditional Curtis-Godson definitions for the effective parameters k̄ e and β e , new definitions for the path averages γ̄ e and δ̄ e are derived. These new definitions are obtained from the fundamental properties of the assumed inverse line strength distribution. A summary of all the models is given as a table of relevant equations for use in practical calculations.

Existence of the Trineutron

The possibility of the existence of a trineutron bound state has been investigated by using a separable $N\ensuremath{-}N$ interaction in the $p$ wave. Two different sets of central and spin-orbit forces of the (L\ifmmode\cdot\else\textperiodcentered\fi{}S) and ${(\mathbf{L}\mathbf{\ifmmode\cdot\else\textperiodcentered\fi{}}\mathbf{S})}^{2}$ types have been used to obtain a detailed fit to the $^{3}P_{j}$ scattering phase shifts. The calculations have been performed for the ${J}^{P}={\frac{1}{2}}^{+}$ state, which was shown by Mitra and Bhasin to be the best possible candidate for such a bound state. The solution of the coupled one-dimensional integral equations, as an eigenvalue problem in the "inverse strength parameter" of the $n\ensuremath{-}n$ interaction, shows that the requisite eigenvalue for zero binding energy for the ${n}^{3}$ system has a sufficiently wide margin over the corresponding quantity obtained from the $p\ensuremath{-}p$ phase shifts. This confirms the earlier conclusion of Mitra and Bhasin based on effective central $p$-wave forces, but is contradictory to the results of variational approaches with conventional potentials given by Okamoto and Davies, and by Barbi. The possible significance of the difference is discussed.

The Limit of Regeneration

It is shown that, at the limit of regeneration, the relative magnitude of received signal in the plate circuit to that impressed on the grid is inversely proportional to the latter. This inverse signal strength law is explained in terms of the characteristics of the tube. Two methods of determining the effective resistance of a regenerative system are outlined. Practical suggestions are offered for the design of regenerative systems.