A Characterisation of the Weylian Structure of Space-Time by Means of Low Velocity Tests

The compatibility axiom in Ehlers, Pirani and Schild's (EPS) constructive axiomatics of the space-time geometry that uses light rays and freely falling particles with high velocity, is replaced by several constructions with low velocity particles only. For that purpose we describe in a space-time with a conformal structure and an arbitrary path structure the radial acceleration, a Coriolis acceleration and the zig-zag construction. Each of these quantities give effects whose requirement to vanish can be taken as alternative version of the compatibility axiom of EPS. The procedural advantage lies in the fact, that one can make null-experiments and that one only needs low velocity particles to test the compatibility axiom. We show in addition that Perlick's standard clock can exist in a Weyl space only.Comment: to appear in Gen.Rel.Gra

Non-Singular Stationary Global Strings

A field-theoretical model for non-singular global cosmic strings is presented. The model is a non-linear sigma model with a potential term for a self-gravitating complex scalar field. Non-singular stationary solutions with angular momentum and possibly linear momentum are obtained by assuming an oscillatory dependence of the scalar field on t, phi and z. This dependence has an effect similar to gauging the global U(1) symmetry of the model, which is actually a Kaluza-Klein reduction from four to three spacetime dimensions. The method of analysis can be regarded as an extension of the gravito-electromagnetism formalism beyond the weak field limit. Some D=3 self-dual solutions are also discussed.Comment: 20 pages Latex, 12 PS figures included. Minor corrections. Version to appear in Phys.Rev.

Fate of the false monopoles: induced vacuum decay

We study a gauge theory model where there is an intermediate symmetry breaking to a meta- stable vacuum that breaks a simple gauge group to a U (1) factor. Such models admit the existence of meta-stable magnetic monopoles, which we dub false monopoles. We prove the existence of these monopoles in the thin wall approximation. We determine the instantons for the collective coordinate that corresponds to the radius of the monopole wall and we calculate the semi-classical tunneling rate for the decay of these monopoles. The monopole decay consequently triggers the decay of the false vacuum. As the monopole mass is increased, we find an enhanced rate of decay of the false vacuum relative to the celebrated homogeneous tunneling rate due to Coleman [1].Comment: 10 pages, 4 figure

Baryon Asymmetry in a Heavy Moduli Scenario

In some models of supersymmetry breaking, modulus fields are heavy enough to decay before BBN. But the large entropy produced via moduli decay significantly dilutes the preexisting baryon asymmetry of the universe. We study whether Affleck-Dine mechanism can provide enough baryon asymmetry which survives the dilution, and find several situations in which desirable amount of baryon number remains after the dilution. The possibility of non-thermal dark matter is also discussed. This provides the realistic cosmological scenario with heavy moduli.Comment: 36 pages, 5 figures; added a reference; v3: minor correction

Space Time Foam: a ground state candidate for Quantum Gravity

A model of space-time foam, made by $N$ wormholes is considered. The Casimir energy leading to such a model is computed by means of the phase shift method which is in agreement with the variational approach used in Refs.[9-14]. The collection of Schwarzschild and Reissner-Nordstr\"{o}m wormholes are separately considered to represent the foam. The Casimir energy shows that the Reissner-Nordstr\"{o}m wormholes cannot be used to represent the foam.Comment: 6 pages.RevTeX with package epsf and two eps figures. To be submitted to the proceedings of the 4th Workshop of `Mysteries, Puzzles And Paradoxes In Quantum Mechanics' Gargnano (Italy), 27 August-1 September 200

Quantum Fermion Hair

It is shown that the Dirac operator in the background of a magnetic %Reissner-Nordstr\"om black hole and a Euclidean vortex possesses normalizable zero modes in theories containing superconducting cosmic strings. One consequence of these zero modes is the presence of a fermion condensate around magnetically charged black holes which violates global quantum numbers.Comment: 16pp (harvmac (l)) and 2 figs.(not included

Phase 1 of the automated array assembly task of the low cost silicon solar array project

The results of a study of process variables and solar cell variables are presented. Interactions between variables and their effects upon control ranges of the variables are identified. The results of a cost analysis for manufacturing solar cells are discussed. The cost analysis includes a sensitivity analysis of a number of cost factors

An Analysis of the Impact of European Union and United States Dairy Policies on EU-U.S. Trade in Milk Protein Concentrate

During 1996-2000, U.S. imports of milk protein concentrate (MPC) increased rapidly. At the same time, Commodity Credit Corporation (CCC) stocks of non-fat dry milk (NFDM) went from nothing to more than 500 million pounds. Consequently, U.S. milk producers attributed low milk prices and dairy farmer income during this period to the increased imports of MPC. U.S. milk producers were especially concerned with MPC imports for two reasons. First, MPC between 40 and 90 percent protein had been classified in subheading 0404.90.10 of the Harmonized Tariff Schedule of the United States (HTS). Thus, MPC was not subject to the tariff-rate quotas applied to many other dairy products. Second, MPC produced in the European Union (EU) and exported to the United States was eligible for production and export subsidies. Along with the high U.S. internal milk protein prices maintained by the Dairy Price Support Program, and volatile world prices of NFDM, these policies created economic rents for trade in MPC between the European Union and the United States. To test the relationship between these policies and U.S. imports of MPC, these economic rents, which were not directly observable, were estimated by combing a set of identifiable variables: (1) the CCC purchase price, (2) the EU export refund, (3) EU casein production aid, and (4) the world price of NFDM as expressed by the Western Europe export price. A vector autoregression model was then estimated using monthly U.S. imports of MPC and the estimate of economic rents. This estimation showed that nearly 40 percent of the variability in U.S. MPC imports was attributable to the estimate of economic rents. These results demonstrate that U.S. and EU policies can not be analyzed in isolation when evaluating the impact of dairy policies on U.S. MPC imports.Agricultural and Food Policy, International Relations/Trade,

Connecting N-representability to Weyl's problem: The one particle density matrix for N = 3 and R = 6

An analytic proof is given of the necessity of the Borland-Dennis conditions for 3-representability of a one particle density matrix with rank 6. This may shed some light on Klyachko's recent use of Schubert calculus to find general conditions for N-representability