Drawer drive for space shuttle vacuum canister

A sliding drawer type canister was designed to contain long duration exposure facility experiments which require vacuum storage before and after space exposure. The elastomeric seals require high closing loads which are generated through camming levers and transmitted through a spring loaded pressure plate. Lubrication was provided by various dry surface coatings. Higher than expected friction required some redesign after which the assembly functioned well and provided good sealing

On the Role of Entanglement in Schroedinger's Cat Paradox

In this paper we re-investigate the core of Schroedinger's 'cat paradox'. We argue that one has to distinguish clearly between superpositions of macroscopic cat states and superpositions of entangled states which comprise both the state of the cat. It is shown, that in the first instance recurrence to decoherence or other mechanisms is not necessary in this special case in order to explain the absence of macroscopic superpositions. Additionally, we present modified versions of two quantum optical experiments as experimenta crucis. Applied rigorously, quantum mechanical formalism reduces the problem to a mere pseudo-paradox.Comment: 10 pages; LaTeX; contact information update

Scalar dark matter in the B-L model

The B-L extension of the Standard Model requires the existence of right-handed neutrinos and naturally realizes the seesaw mechanism of neutrino mass generation. We study the possibility of explaining the dark matter in this model with an additional scalar field that is a singlet of the Standard Model but charged under $U(1)_{B-L}$. An advantage of this scenario is that the stability of the dark matter can be guaranteed by appropriately choosing its B-L charge, without the need of an extra ad hoc discrete symmetry. We investigate in detail the dark matter phenomenology of this model. We show that the observed dark matter density can be obtained via gauge or scalar interactions, and that semi-annihilations could play an important role in the latter case. The regions consistent with the dark matter density are determined in each instance and the prospects for detection in future experiments are analyzed. If dark matter annihilations are controlled by the B-L gauge interaction, the mass of the dark matter particle should lie below 5 TeV and its direct detection cross section can be easily probed by XENON1T; if instead they are controlled by scalar interactions, the dark matter mass can be much larger and the detection prospects are less certain. Finally, we show that this scenario can be readily extended to accommodate multiple dark matter particles.Comment: 24 page

Hot Atmospheres, Cold Gas, AGN Feedback and the Evolution of Early Type Galaxies: a Topical Perspective

Most galaxies comparable to or larger than the mass of the Milky Way host hot, X-ray emitting atmospheres, and many such galaxies are radio sources. Hot atmospheres and radio jets and lobes are the ingredients of radio-mechanical active galactic nucleus (AGN) feedback. While a consensus has emerged that such feedback suppresses cooling of hot cluster atmospheres, less attention has been paid to massive galaxies where similar mechanisms are at play. Observation indicates that the atmospheres of elliptical and S0 galaxies were accreted externally during the process of galaxy assembly and augmented significantly by stellar mass loss. Their atmospheres have entropy and cooling time profiles that are remarkably similar to those of central cluster galaxies. About half display filamentary or disky nebulae of cool and cold gas, much of which has likely cooled from the hot atmospheres. We review the observational and theoretical perspectives on thermal instabilities in galactic atmospheres and the evidence that AGN heating is able to roughly balance the atmospheric cooling. Such heating and cooling may be regulating star formation in all massive spheroids at late times.Comment: Final versio

Apparatus for making curved reflectors Patent

Forming mold for polishing and machining curved solar magnesium reflector with reinforcing rib

Process sequence produces strong, lightweight reflectors of excellent quality

Large compound curved surfaces for collecting and concentrating radiation are fabricated by the use of several common machining and forming processes. Lightweight sectors are assembled into large reflectors. With this concept of fabrication, integrally stiffened reflective sectors up to 25 square feet in area have been produced

Has the Euro affected the choice of invoicing currency?

We present a new approach to study empirically the effect of the introduction of the euro on the pattern of currency invoicing. Our approach uses a compositional multinomial logit model, in which currency choice is explained by both currency-specific and country-specific determinants. We use unique quarterly panel data on the invoicing of Norwegian imports from OECD countries for the 1996-2006 period. We find that eurozone countries have substantially increased their share of home currency invoicing after the introduction of the euro, whereas the home currency share of non-eurozone countries fell slightly. In addition, the euro as a vehicle currency has overtaken the role of the US dollar in Norwegian imports. The substantial rise in producer currency invoicing by eurozone countries is primarily caused by a drop in inflation volatility and can only to a small extent be explained by an unobserved euro effect. JEL Classification: F33, F41, F42, E31, C25.Euro, invoicing currency, exchange rate risk, inflation volatility, vehicle currencies, compositional multinomial logit.

Method and apparatus for making curved reflectors Patent

Fabrication of curved reflector segments for solar mirro