The construction of self-consistent models for outflowing stellar envelopes

The article presents self-consistent computations of the spherically symmetric envelope of a massive (M=20M _⊙) star whose envelope is flowing outward under the action of continuum radiation pressure. A system of equations describing the out flow for arbitrary optical depth, degree of ionization, and opacity κ are obtained. A numerical solution is obtained for the case of constant κ and degree of ionization via approaching integrations from the singularities and smooth joining in the intermediate region. Asymptotic solutions are found in the vicinity of the sonic point and the singularity at infinity.     

Some Problems of Clastogenic Mica Transformation during Anchimetamorphism (Metagenesis)

The transformation of clastogenic muscovite and biotite from the Tyumen superdeep well was studied with the SEM and microprobe techniques. It was shown that under conditions of anchimetamorphism (metagenesis), the white mica becomes unstable and may be replaced by several newly formed minerals. In particular, the brammallite, a sodic analogue of illite, is formed at the expense of sodic component of muscovite. The chloritization of mica provokes the removal of excess silica, which is present in the anchizone as a readily soluble in water modification rather than quartz. The release of excess silica as a result of clastogenic mica destruction may be a source of rock silification. As follows from the review of experimental data on silica solubility, the replacement of many silicate minerals leads to the formation of excess silica. This process can be highly extensive during the breakdown of clastogenic minerals.     

Triple approaches in the plane isosceles equal-mass three-body problem

We analyze flyby-type triple approaches in the plane isosceles equal-mass three-body problem and in its vicinity. At the initial time, the central body lies on a straight line between the other two bodies. Triple approaches are described by two parameters: virial coefficient k and parameter $\mu = \dot r/\sqrt {\dot r^2 + \dot R^2 }$ , where $\dot r$ is the relative velocity of the extreme bodies and $\dot R$ is the velocity of the central body relative to the center of mass of the extreme bodies. The evolution of the triple system is traceable until the first turn or escape of the central body. The ejection length increases with closeness of the triple approach (parameter k). The longest ejections and escapes occur when the extreme bodies move apart with a low velocity at the time of triple approach. We determined the domain of escapes; it corresponds to close triple approaches (k>0.8) and to μ in the range ?0.2<μ<0.7. For small deviations from the isosceles problem, the evolution does not differ qualitatively from the isosceles case. The domain of escapes decreases with increasing deviations. In general, the ejection length increases for wide approaches and decreases for close approaches.     

Emissions control and reduction

A brief review of the information available on technological means for reducing anthropogenic emissions of greenhouse gases is provided. No assessment of economic or institutional difficulties for their implementation is attempted. A few cost figures are quoted where available, usually at the single-unit, microeconomic level, and further aggregation of the data is required to estimate global costs. Considerable additional analysis is required to do the latter, since simple summation of micro-level figures will in general not correctly yield macro level costs. It follows that no conclusions can be drawn from the information provided in this paper as to the preferred, most effective strategies for abating emission growths. The review should be viewed as providing a snap-shot picture of the data available as of today that is needed as input to an analysis of means and costs for achieving global scale reduction in emissions levels.     

Seasonal abundance of brachyuran crab larvae in a tropical estuary: Gulf of Nicoya,Costa Rica,Central America

Brachyuran crab larvae were sampled approximately monthly at four stations in the Gulf of Nicoya, a tropical estuary on the Pacific coast of Costa Rica, Central America. The gulf was divided into two regions based on physical and chemical characteristics. Larvae were identified to five families: Ocypodidae, Pinnotheridae, Portunidae, Majidae, Xanthidae. The abundance and distribution of these taxa were similar to that found in temperature estuaries of North America. Ocypodids, pinnixids, and xanthids were most common in the estuarine upper-gulf region while portunids were more common in the lower gulf. Majids were found in small numbers in the lower gulf. Only the ocypodids showed a consistent pattern in vertical distribution; larvae of this taxon were always more common in surface water. There was no consistent pattern in the seasonal abundance of the various taxa when compared among stations.     

Normalized 87Sr86Sr by multiple collection and comparison to a standard

A system for precisely determining normalized ${}^{87}\text{Sr}{}^{86}\text{Sr}$ by comparing unknown to standard in a solid-source quadruple-collector mass spectrometer is outlined. This is made possible by a mathematical approximation in the data-reduction process.