Aircraft-crash-locating transmitter features design improvements

Crash locater is automatically ejected from aircraft at time of crash and begins transmitting at emergency radio frequencies monitored by all airports and airport control towers. Advantages are smaller size, simpler design and installation, extended transmitting range and life, greater deployment reliability and increased crash resistance

Geosynchrotron radio emission from CORSIKA-simulated air showers

Simulations of radio emission from extensive air showers we have published so far were performed with a Monte Carlo code using analytical parametrisations to describe the spatial, temporal, energy and angular particle distributions in the air shower. A new version of our simulation code, which replaces these parametrisations with precise, multi-dimensional histograms derived from per-shower CORSIKA simulations, is now available. The new code allows an independent selection between parametrisation and histogram for each of the relevant distributions, enabling us to study the changes arising from using a more realistic air shower model in detail. We describe the new simulation strategy, present some initial results and discuss the new possibilities.Comment: 6 pages, Proceedings of the ARENA2006 workshop, Newcastle, England; to be published in Journal of Physics: Conference Series (JPCS

The equations defining blowup algebras of height three Gorenstein ideals

We find the defining equations of Rees rings of linearly presented height three Gorenstein ideals. To prove our main theorem we use local cohomology techniques to bound the maximum generator degree of the torsion submodule of symmetric powers in order to conclude that the defining equations of the Rees algebra and the special fiber ring have the same image in the symmetric algebra. We show that this image is the unmixed part of the ideal generated by the maximal minors of a matrix of linear forms which is annihilated by a vector of indeterminates, and otherwise has maximal possible grade. An important step of the proof is the calculation of the degree of the variety parametrized by the forms generating the grade three Gorenstein ideal.Comment: Numerous improvements to the exposition have been mad

In-vitro demonstration of cell-mediated immunity to vaccinia virus in man

Cell mediated immunity to vaccinia virus in man was studied by lymphocyte transformation. Vaccinia antigen, propagated on BHK-21 and Vero cells, could be used successfully for in-vitro testing after partial purification as well as crude infectious homogenates. Vaccinia antigen preparations were effective both in the infective and the inactivated state. Inactivation was usually accompanied with a certain loss of stimulating activity. Development of cell mediated immune response in-vitro after first vaccination was investigated in 17 adults. Vaccinia virus specific lymphocyte transformation was seen in the second week after vaccination in all cases. Following revaccination no increase of lymphocyte transformation ratio could be observed in 11 persons studied. At the same time the titers of humoral antibodies were elevated

IR-transmission glasses formed from oxides of bismuth and tellurium

Bismuth trioxide-tellurium dioxide glasses have improved infrared transmission characteristics

Planar leaky light-guides and couplers

A quantitative theory of light propagation in a dielectric slab guide with general cladding media is presented. It is based on a plane wave which bounces in a zigzag fashion along the guide as a result of total or partial reflections at the two surfaces of the film. Two mechanisms are considered which contribute to the attenuation of the guide: losses due to absorption in the slab and cladding materials, and radiation losses if the guide is a leaky one. We point out the significance of the Goos-Hänchen effect for all questions relating to the power flow in the slab guide. The theory is illustrated by discussing dispersion and attenuation of guides with various low-index and high-index claddings, operating above and below cutoff. The low-index leaky guide is considered particularly in detail. Its high attenuation by leakage can be reduced to practically acceptable values (<1d B/cm) by increasing the film thickness to ≳ 40λ. One application of this guide is in the leaky wave coupler. This coupler may be viewed as a prism-film coupler simplified by omission of the gap. It offers a new approach to the problem of broad-band coupling to thin-film light guides

Scaling laws in spherical shell dynamos with free-slip boundaries

Numerical simulations of convection driven rotating spherical shell dynamos have often been performed with rigid boundary conditions, as is appropriate for the metallic cores of terrestrial planets. Free-slip boundaries are more appropriate for dynamos in other astrophysical objects, such as gas-giants or stars. Using a set of 57 direct numerical simulations, we investigate the effect of free-slip boundary conditions on the scaling properties of heat flow, flow velocity and magnetic field strength and compare it with earlier results for rigid boundaries. We find that the nature of the mechanical boundary condition has only a minor influence on the scaling laws. We also find that although dipolar and multipolar dynamos exhibit approximately the same scaling exponents, there is an offset in the scaling pre-factors for velocity and magnetic field strength. We argue that the offset can be attributed to the differences in the zonal flow contribution between dipolar and multipolar dynamos.Comment: 10 pages, 9 figures, 1 table. To appear in ICARU