Omni-directional anisotropic molecular trap Patent

Omnidirectional anisotropic molecular trap, used with vacuum pump to simulate space environments for testing spacecraft component

Seasonal and inter-annual temperature variability in the bottom waters over the western Black Sea shelf

Long-term changes in the state of the Bottom Shelf Water (BSW) on the Western shelf of the Black Sea are assessed using analysis of intra-seasonal and inter-annual temperature variations. For the purpose of this study the BSW is defined as such shelf water mass between the seabed and the upper mixed layer (bounded by the σθ = 14.2 isopycnal) which has limited ability to mix vertically with oxygen-rich surface waters during the warm season due to formation of a seasonal pycnocline. A long-term time series of temperature anomalies in the BSW is constructed from in-situ observations taken over the 2nd half of the 20th century. The BSW is shown to occupy nearly half of the shelf area during the summer stratification period (May–November).The results reveal a warm phase in the 1960s/70s, followed by a cold phase between 1985 and 1995 and a further warming after 1995. The transition between the warm and cold periods coincides with a regime shift in the Black Sea ecosystem. While it was confirmed that the memory of winter convection is well preserved over the following months in the deep sea, the signal of winter cooling in the BSW significantly reduces during the warm season. The potential of the BSW to ventilate horizontally during the warm season with the deep-sea waters is assessed using isopycnic analysis of temperature variations. It is shown that temperature in the BSW is stronger correlated with the temperature of Cold Intermediate Waters (CIW) in the deep sea than with the severity of the previous winters, thus indicating that the isopycnal exchanges with the deep sea are more important for inter-annual/inter-decadal variability of the BSW on the western Black Sea shelf than effects of winter convection on the shelf itself

Hydrodynamics of Binary Coalescence.I. Polytropes with Stiff Equations of State

We have performed a series of three-dimensional hydrodynamic calculations of binary coalescence using the smoothed particle hydrodynamics (SPH) method. The initial conditions are exact polytropic equilibrium configurations with \gam > 5/3, on the verge of dynamical instability. We calculate the emission of gravitational radiation in the quadrupole approximation. The fully nonlinear development of the instability is followed until a new equilibrium configuration is reached. We find that the properties of this final configuration depend sensitively on both the compressibility and mass ratio. An {\em axisymmetric} merged configuration is always produced when \gam\lo2.3. As a consequence, the emission of gravitational radiation shuts off abruptly right after the onset of dynamical instability. In contrast, {\em triaxial\/} merged configurations are obtained when \gam\go2.3, and the system continues to emit gravitational waves after the final coalescence. Systems with mass ratios $q\ne1$ typically become dynamically unstable before the onset of mass transfer. Stable mass transfer from one neutron star to another in a close binary is therefore probably ruled out. The maximum amplitude $h_{max}$ and peak luminosity $L_{max}$ of the gravitational waves emitted during the final coalescence are nearly independent of \gam, but depend very sensitively on the mass ratio $q$.Comment: 27 pages, uuencoded compressed postscript, 16 figures upon request from [email protected], IAS-AST-94-

Head-On Collision of Neutron Stars As A Thought Experiment

The head-on collision of identical neutron stars from rest at infinity requires a numerical simulation in full general relativity for a complete solution. Undaunted, we provide a relativistic, analytic argument to suggest that during the collision, sufficient thermal pressure is always generated to support the hot remnant in quasi-static stable equilibrium against collapse prior to slow cooling via neutrino emission. Our conclusion is independent of the total mass of the progenitors and holds even if the remnant greatly exceeds the maximum mass of a cold neutron star.Comment: to appear in Physical Review D (revtex, 3 figs, 5 pgs

Observability of the neutrino flux from the inner region of the galactic disk

The observability of galactic neutrinos in a detector of 10 billion tons of water with an observing time of a few years is explored. Although the atmospheric flux exceeds the galactic flux considerably at energies greater than or equal to 1 TeV, the latter may still provide a marginally observable signal owing to its directionality. Galactic muon neutrinos with energy greater than or equal to 1 TeV will produce a signal approximately 2 sigma above the atmospheric background over a four year period. If electron neutrinos can also be studied with the deep underwater muon and neutrino detector, then galactic electron neutrinos above 1 TeV would give an approximate 4 to 5 sigma signal above the electron neutrino background over a four year integration time