Fluid injection device for high-pressure systems

Screw activated device, consisting of a compressor, shielded replaceable ampules, a multiple-element rubber gland, and a specially constructed fluid line fitting, injects measured amounts of fluids into a pressurized system. It is sturdy and easily manipulated

Gravitational instantons, extra dimensions and form fields

A broad class of higher dimensional instanton solutions are found for a theory which contains gravity, a scalar field and antisymmetric tensor fields of arbitrary rank. The metric used, a warp product of an arbitrary number of any compact Einstein manifolds, includes many of great interest in particle physics and cosmology. For example 4D FRW universes with additional dimensions compactified on a Calabi-Yau three fold, a torus, a compact hyperbolic manifold or a sphere are all included. It is shown that the solution of this form which dominates the Hartle Hawking path integral is always a higher dimensional generalisation of a Hawking Turok instanton when the potential of the scalar field is such that these instantons can exist. On continuation to Lorentzian signature such instantons give rise to a spacetime in which all of the spatial dimensions are of equal size and where the spatial topology is that of a sphere. The extra dimensions are thus not hidden. In the case where the potential for the scalar field is generated solely by a dilatonic coupling to the form fields we find no integrable instantons at all. In particular we find no integrable solutions of the type under consideration for the supergravity theories which are the low energy effective field theories of superstrings.Comment: 11 pages, 4 figure

Development of a refrigeration system for lunar surface and spacecraft applications

An evaluation of refrigeration devices suitable for potential lunar surface and spacecraft applications was performed. The following conclusions were reached: (1) the vapor compression system is the best overall refrigeration system for lunar surface and spacecraft applications and the single phase radiator system is generally preferred for earth orbit applications, (2) the vapor compression cycle may have some application for simultaneous heating and cooling, (3) a Stirling cycle refrigerator was selected for the manned cabin of the space shuttle, and (4) significant increases in payload heat rejection can be obtained by a kit vapor compression refrigerator added to the shuttle R-21 loop. The following recommendations were made: (1) a Stirling cycle refrigerator may be used for food freezer and biomedical sample storage, (2) the best system for a food freezer/experiments compartment for an earth orbit space station has not been determined, (3) a deployed radiator system can be designed for large heat loads in earth orbit

How is a Closed String Loop like a Black Hole?

We demonstrate that under plausible assumptions the entropy and temperature associated with the small oscillations on a circular loop of radius $R$ and a black hole of mass $M=R/2G$ are identical.Comment: 6 pages, uses harvma

Cosmological matching conditions

We investigate the evolution of scalar metric perturbations across a sudden cosmological transition, allowing for an inhomogeneous surface stress at the transition leading to a discontinuity in the local expansion rate, such as might be expected in a big crunch/big bang event. We assume that the transition occurs when some function of local matter variables reaches a critical value, and that the surface stress is also a function of local matter variables. In particular we consider the case of a single scalar field and show that a necessary condition for the surface stress tensor to be perturbed at the transition is the presence of a non-zero intrinsic entropy perturbation of the scalar field. We present the matching conditions in terms of gauge-invariant variables assuming a sudden transition to a fluid-dominated universe with barotropic equation of state. For adiabatic perturbations the comoving curvature perturbation is continuous at the transition, while the Newtonian potential may be discontinuous if there is a discontinuity in the background Hubble expansion.Comment: 12 pages, no figure

Salt stabilizer for preventing chlorine depletion and increasing shelf-life of potable water - A concept

Proposed concept, based on law of mass action uses addition of salt to increase chlorine ions produced in sodium hydrochlorite solutions, thereby increasing solution shelf-life. This technique is not costly. Usefulness will be determined by acceptability of salt in product undergoing long shelf-life

Constraining the quintessence equation of state with SnIa data and CMB peaks

Quintessence has been introduced as an alternative to the cosmological constant scenario to account for the current acceleration of the universe. This new dark energy component allows values of the equation of state parameter $w_{Q}^0\geq-1$, and in principle measurements of cosmological distances to Type Ia supernovae can be used to distinguish between these two types of models. Assuming a flat universe, we use the supernovae data and measurements of the position of the acoustic peaks in the Cosmic Microwave Background (CMB) spectra to constrain a rather general class of Quintessence potentials, including inverse power law models and recently proposed Supergravity inspired potentials. In particular we use a likelihood analysis, marginalizing over the dark energy density $\Omega_{Q}$, the physical baryon density $\Omega_{b}h^2$ and the scalar spectral index $n$, to constrain the slopes of our Quintessence potential. Considering only the first Doppler peak the best fit in our range of models gives $w_{Q}^0\sim-0.8$. However, including the SnIa data and the three peaks, we find an upper limit on the present value of the equation of state parameter, $-1\leq w_{Q}^0\leq-0.93$ at $2\sigma$, a result that appears to rule out a class of recently proposed potentials.Comment: Accepted for pubblication in PRD, 7 pages, 6 figures. New revised analysi