On the area of the symmetry orbits in T2T^2 symmetric spacetimes with Vlasov matter

This paper treats the global existence question for a collection of general relativistic collisionless particles, all having the same mass. The spacetimes considered are globally hyperbolic, with Cauchy surface a 3-torus. Furthermore, the spacetimes considered are isometrically invariant under a two-dimensional group action, the orbits of which are spacelike 2-tori. It is known from previous work that the area of the group orbits serves as a global time coordinate. In the present work it is shown that the area takes on all positive values in the maximal Cauchy development.Comment: 27 pages, version 2 minor changes and correction

Water production models for Comet Bradfield (1979 l)

The IUE observations of Comet Bradfield (1979 l) made 10 January 1980 to 3 March 1980 permit a detailed study of water production for this comet. Brightness measurements are presented for all three water dissociation products, H, O, and OH, and comparisons are made with model predictions. The heliocentric variation of the water production rate was derived

Reply to "Comment on 'Precision measurement of the Casimir-Lifshitz force in a fluid'"

We have reviewed the Comment of Geyer et al. [arXiv:0708.1548] concerning our recent work [Phys. Rev. A 75, 060102 (R) (2007)], and while we disagree with their criticisms, we acknowledge them for giving us the opportunity to add interesting addition material and a more detailed description of our experiment. We describe further our calculation and explain why a more sophisticated model is not warranted. We also present detailed experiments on the effects of electrostatic forces in our measurements and show that the contribution due to work function differences is small and that the residual electrostatic force is dominated by trapped charges and external fields. Finally, we estimate the effect of double layer interactions. These additional calculations and measurements support our original conclusion that the experimental results are consistent with the Lifshitz theory

Ecological Study of the Effects of Strip Mining on the Microbiology of Streams

The microflora of Cane Branch of Beaver Creek in McCreary County, Kentucky, which drains an area that was strip-mined between 1955 and 1959, was studied and compared with that of Helton Branch which drains a comparable area where there has been no mining. Differences include: the establishment of Ferrcbacillus ferrooxidans, for which procedures were developed for direct colony isolation from the stream; fewer saprophytic bacteria; more numerous and more diversified filamentous and unicellular fungi; and characteristic differences in algal flora. Representatives of 42 genera of filamentous fungi were identified. Of these, 21 were isolated only from Cane Branch. Representatives of five genera of unicellular fungi were found. One, Rhoclotorula, was found consistently in Cane Branch but never in Helton Branch. From 1966 to 1968, Bumilleria appears to have established itself as the dominate alga in Cane Branch at same distance downstream from the strip-mine drainage area, Seasonal differences in the microflora appear to be relatively insignificant, except for the algae

High velocity spikes in Gowdy spacetimes

We study the behavior of spiky features in Gowdy spacetimes. Spikes with velocity initially high are, generally, driven to low velocity. Let n be any integer greater than or equal to 1. If the initial velocity of an upward pointing spike is between 4n-3 and 4n-1 the spike persists with final velocity between 1 and 2, while if the initial velocity is between 4n-1 and 4n+1, the spiky feature eventually disappears. For downward pointing spikes the analogous rule is that spikes with initial velocity between 4n-4 and 4n-2 persist with final velocity between 0 and 1, while spikes with initial velocity between 4n-2 and 4n eventually disappear.Comment: discussion of constraints added. Accepted for publication in Phys. Rev.

Manufacture of Gowdy spacetimes with spikes

In numerical studies of Gowdy spacetimes evidence has been found for the development of localized features (spikes) involving large gradients near the singularity. The rigorous mathematical results available up to now did not cover this kind of situation. In this work we show the existence of large classes of Gowdy spacetimes exhibiting features of the kind discovered numerically. These spacetimes are constructed by applying certain transformations to previously known spacetimes without spikes. It is possible to control the behaviour of the Kretschmann scalar near the singularity in detail. This curvature invariant is found to blow up in a way which is non-uniform near the spike in some cases. When this happens it demonstrates that the spike is a geometrically invariant feature and not an artefact of the choice of variables used to parametrize the metric. We also identify another class of spikes which are artefacts. The spikes produced by our method are compared with the results of numerical and heuristic analyses of the same situation.Comment: 25 page