One-particle reducible contribution to the one-loop scalar propagator in a constant field

Recently, Gies and Karbstein showed that the two-loop Euler-Heisenberg Lagrangian receives a finite one-particle reducible contribution in addition to the well-known one-particle irreducible one. Here, we demonstrate that a similar contribution exists for the propagator in a constant field already at the one-loop level, and we calculate this contribution for the scalar QED case. We also present an independent derivation of the Gies-Karbstein result using the worldline formalism, treating the scalar and spinor QED cases in a unified manner.Comment: 13 pages, 4 figures. Minor corrections mad

Complete Hydrogen Storage System by ISRU

New technologies make it possible to build in space a complete hydrogen storage system using ISRU methods and techniques. Hydrogen can be stored in a solid-state form on the surface atoms of high surface area matrices such as those of porous silicon. Silicon is abundant in regolith and can be purified using a purely mechanical means which results in particulates in the scale range of tens of nanometers. Reagents used to porosify these nano-particles can be regenerated thermally to essentially eliminate the need for resupply from earth. Catalysts are needed to divide dihydrogen gas into atomic hydrogen for solid-state adsorption and to mediate the temperatures and pressures of charge and discharge into ranges easily achievable with simple equipment. Recent research has identified the utility of non-platinum group catalyst materials which are widespread on the moon. Rapid discharge, needed for propulsion, is possible with infra-red illumination at wavelengths which pass through pure silicon but are absorbed by the silicon-hydrogen bond. Such IR emitters can be fabricated by embossing of silica and additive manufacturing of metals. Control and power electronics can be fabricated using a patented process designed for space operations, and built on either silicon or silicon carbide substrates derived from regolith. Bringing these five technologies together for the first time allows a system which can be fed with moderate pressure gaseous hydrogen at moderate temperatures, stored for long durations with minimum loss, then released upon demand across a wide range of controllable rates. Such a system can displace the need for cryogenic hydrogen storage. Being suitable to bottom-up fabrication using only in-space materials makes this a “green” ISRU technology to store hydrogen for fuel cells, rocket engines, and chemical processes

Pathogenicity in Verticillium on strawberry plants

In the most common strawberry cv. ’Elsanta’, Verticillium infection can lead to rapid wilt and even death of plants. It is known, that a dead plant can be located directly beside vital ones. In a survey of 8 fields in Brandenburg, Mecklenburg- Vorpommern, Sachsen-Anhalt and Sachsen, 432 genotypes of Verticillium dahliae Kleb. were isolated from wilted and even vital plants from 8 fields and classified by PCR-fingerprints. For strawberries, the genotypes can be classified as apathogenic, weakly and highly pathogenic according to the results of climate chamber experiments on strawberry transplants. At landscape scale, similarity analysis of the PCR fingerprints of 432 genotypes resulted in 13 genetic subtypes. Several of these subtypes occurred at all fields, whereas 1 subtype was found in one location only. At field scale, 2 to 11 different subtypes per field were observed. Vital plants were colonised by up to 9 subtypes, wilted plants by up to 11 subtypes. Population structure of Verticillium subtypes is different between vital and wilted plants, the same subtypes can occur in either plant group. In our plot experiments, wilt symptoms could be reduced by changing the Verticillium population structure in the plant. Inoculation of plants with a mixture of three Verticillium genotypes sustained plant vitality over a period of 15 months (WO 2007/051654)

Comment on "Anderson transition in disordered graphene"

We comment on a recent letter by Amini et al. (EPL 87, 37002 (2009)) concerning the existence of a mobility edge in disordered graphene.Comment: 3 pages, 3 figure

Active vision-based localization for robots in a home-tour scenario

Self-Localization is a crucial task for mobile robots. It is not only a requirement for auto navigation but also provides contextual information to support human robot interaction (HRI). In this paper we present an active vision-based localization method for integration in a complex robot system to work in human interaction scenarios (e.g. home-tour) in a real world apartment. The holistic features used are robust to illumination and structural changes in the scene. The system uses only a single pan-tilt camera shared between different vision applications running in parallel to reduce the number of sensors. Additional information from other modalities (like laser scanners) can be used, profiting of an integration into an existing system. The camera view can be actively adapted and the evaluation showed that different rooms can be discerned

An Improved Heat Kernel Expansion from Worldline Path Integrals

The one--loop effective action for the case of a massive scalar loop in the background of both a scalar potential and an abelian or non--abelian gauge field is written in a one--dimensional path integral representation. From this the inverse mass expansion is obtained by Wick contractions using a suitable Green function, which allows the computation of higher order coefficients. For the scalar case, explicit results are presented up to order O(T**8) in the proper time expansion. The relation to previous work is clarified.Comment: 13 pages, Plain TEX, no figure

Solid state convection models of lunar internal temperature

Thermal models of the Moon were made which include cooling by subsolidus creep and consideration of the creep behavior of geologic material. Measurements from the Apollo program on seismic velocities, electrical conductivity of the Moon's interior, and heat flux at two locations were used in the calculations. Estimates of 1500 to 1600 K were calculated for the temperature, and one sextillion to ten sextillion sq cm/sec were calcualted for the viscosity of the deep lunar interior