Local existence of solutions to the Euler–Poisson system,including densities without compact support

Local existence and well posedness for a class of solutions for the Euler Poisson system is shown. These solutions have a density ρ which either falls off at infinity or has compact support. The solutions have finite mass, finite energy functional and include the static spherical solutions for $\gamma =\frac{6}{5}$. The result is achieved by using weighted Sobolev spaces of fractional order and a new non-linear estimate which allows to estimate the physical density by the regularised non-linear matter variable. Gamblin also has studied this setting but using very different functional spaces. However we believe that the functional setting we use is more appropriate to describe a physical isolated body and more suitable to study the Newtonian limit.     

Radiative transfer through an arbitrarily thick,scattering atmosphere

A method is presented for solving the equation of radiative transfer in a vertically inhomogeneous planetary atmosphere. The method, based on the spherical harmonics expansion, can be used to compute models with an arbitrarily large optical thickness and any scattering phase function. It is extremely efficient, requiring the equivalent of only two matrix multiplications per layer. This efficiency combined with its stability makes the method useful for computing realistic models of planetary atmospheres. To illustrate the range of validity of this method, we compute the plane albedo from model atmospheres containing clouds with optical thicknesses ranging from 0 to 10⁶.     

A modified Henyey method for computing radiative transfer hydrodynamics

The implicit hydrodynamic code of Kutter and Sparks⁽¹⁾ has beenmodified to include radiative transfer effects in the optically thin zones of the model. This modification is described and the convergence of the method is discussed. Hydrodynamic models of a classical Cepheid with a period of 12^d computed using the diffusion approximation and this modified method are compared.     

A characterization of the minimum cycle mean in a digraph

Let C = (V,E) be a digraph with n vertices. Let f be a function from E into the real numbers, associating with each edge e ∈ E a weight$\text{?(e)}$. Given any sequence of edges σ = e₁,e₂,…,e_p define w(σ), the weight of σ, as $\text{∑}\text{i =}\text{1}\text{p}\text{?(e}{}_{\mathrm{i}}\text{)}$, and define m(σ), the mean weight of σ, as w(σ)?p. Let $\text{λ}{}^1\text{=}\text{min}{}_{\mathrm{C}}\text{m(C)}$ where C ranges over all directed cycles in G; λ¹ is called the minimum cycle mean. We give a simple characterization of λ¹, as well as an algorithm for computing it efficiently.     

Der Einfluß von Molmasse und Füllstoffen auf die rheologischen Kenngrößen von 1,4-cis-Polyisopren

The dependence of the rheological properties of synthetic 1,4-cis-polyisoprenes and their mixtures on mean molecular weight, molecular weight distribution, filler type and filler concentration is investigated. Particular consideration is given to the influence of the filler on the relations between the molecular and rheological properties of polyisoprene. Rheological models are suggested for calculating the viscoelastic characteristics of isoprene rubbers.     

The human autodiagnostic system (Rexed's laminae as diagnostic neuroprocessors)

A position is formulated according to which the therapeutic effect of a puncture action is a result of the correction of defects in the human autodiagnostic system (ADS). The structure and functions of the ADS are examined from the points of view of pattern recognition, neurocomputing, and neurophysiology. The necessary conditions that the ADC must satisfy are formulated. It is shown that the theoretical conditions are satisfied by Rexed's laminae, which are a part of the central nervous system and form the grey matter of the spinal cord. The available biochemical and morphological data are utilized in an examination of the operating mechanism of Rexed's laminae as a whole (as an ADS) and each lamina individually (as neuroprocessors that perform specific functions). Potential defects in the recognition system and methods for their correction by signals produced at biological active points by EHF puncture are examined.P. N. Lebedev Physics Institute. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 37, No. 1, pp. 57–78, January, 1994.     

Determination of trace amounts of gold in the presence of rare earth elements in rock samples from Makhtesh Ramon (Southern Israel), by instrumental epithermal neutron activation analysis

Epithermal neutron activation analysis (ENAA), followed by high resolution gamma-ray spectrometry, was applied to determine trace amounts of Au in the presence of rare earth elements (REE) from vein samples in the basaltic rocks of Makhtesh Ramon, located in southern Israel. The contribution of¹⁵²Eu (411.1 KeV) to the 411.8 keV peak of¹⁹⁸Au was determined using multiple gamma-peak, ratios derived from Eu standards and mixtures of Au and Eu. The concentration of Au was found to be in the range of 10–80 ppb. A group of rare earth elements: La, Eu, Ce, Tb, Sm, Lu, Yb was identified; the concentration of Eu was found to be 0.5 ppm.     

Highly efficient doubling of a high-repetition-rate diode-pumped laser with bulk periodically poled KTP

An internal doubling efficiency of 64% at 2 MW/cm(2)was obtained in a single-pass configuration with an uncoated, 1-cm-long, bulk periodically poled KTP crystal placed outside the resonator of a pulsed, diode-pumped Nd:YAG laser. An average of 4.8W of green light was obtained from a 7.5-W pump beam inside the crystal. Doubling efficiency exceeded 50% at levels of 0.75 MW/cm(2). The measured thermal tolerance of the doubling process (FWHM) was 3.3( degrees )C cm, and the measured temperature tuning coefficient was 0.053 nm/( degrees )C .