Run-in with chemical additive protects gear surface

Run-in treatment provides a protective coating on turbopump gear surfaces so that they are capable of operation under marginal conditions in mineral oil and diester lubricants. This treatment protects highly loaded gears during relatively short-term operation

Microscale application of column theory for high resolution force and displacement sensing

We present the design, fabrication and experimental validation of a novel device that exploits the amplification of displacement and attenuation of structural stiffness in the post-buckling deformation of slender columns to obtain pico-Newton force and nanometer displacement resolution even under an optical microscope. The extremely small size, purely mechanical sensing scheme and vacuum compatibility of the instrument makes it compatible with existing visualization tools of nanotechnology. The instrument has a wide variety of potential applications ranging from electro-mechanical characterization of one dimensional solids to single biological cells

Noise characterization for resonantly-enhanced polarimetric vacuum magnetic-birefringence experiments

In this work we present data characterizing the sensitivity of the Bir\'{e}fringence Magnetique du Vide (BMV) instrument. BMV is an experiment attempting to measure vacuum magnetic birefringence (VMB) via the measurement of an ellipticity induced in a linearly polarized laser field propagating through a birefringent region of vacuum in the presence of an external magnetic field. Correlated measurements of laser noise alongside the measurement in the main detection channel allow us to separate measured sensing noise from the inherent birefringence noise of the apparatus. To this end we model different sources of sensing noise for cavity-enhanced polarimetry experiments, such as BMV. Our goal is to determine the main sources of noise, clarifying the limiting factors of such an apparatus. We find our noise models are compatible with the measured sensitivity of BMV. In this context we compare the phase sensitivity of separate-arm interferometers to that of a polarimetry apparatus for the discussion of current and future VMB measurements

Dependence of inner-shell vacancy production upon distance in hard Li-Al collisions

We match the predictions of molecular-dynamics simulations of 1.2 keV and 2.0 keV 7Li+ scattered from Al(100) to observed total Li atom spectra measured by time-of-flight spectroscopy. In doing so we determine the relevant parameters in a simple distance of closest approach model for the probability of production of single and double vacancies in the Li 1s shell during hard Li-Al collisions. In the standard Fano-Lichten model of vacancy production, vacancies are produced with unit probability if the collision is hard enough to force the collision partners past some critical distance of closest approach. We find that such an assumption is insufficient to fit our simulations to experimental observations, and that we must allow for a gradual turning on of the vacancy production probability as the distance of closest approach decreases. The resulting model may be useful in modeling atomic excitation effects in simulations of other ion-impact processes

A CROSS-SECTION ANALYSIS OF INTRA-INDUSTRY TRADE IN THE U.S. PROCESSED FOOD AND BEVERAGE SECTORS

This paper analyzes the determinants of variation across industries in levels of intra-industry trade (IIT) for a sample of 36 U.S. processed food and beverage industries in 1987, previous studies of intra-industry trade having focused on industry characteristics in the manufacturing sectors. The determinants predicted by IIT theory are measures of product differentiation, economies of scale, and imperfect competition; the results of this analysis indicate that IIT variation across the food and beverage industries is positively related to product differentiation, U.S. total trade, similarity of tariff barriers among trade partners, and economies of scope, but negatively related to industry concentration.International Relations/Trade,

LOCATION OF VERTICALLY LINKED INDUSTRIES UNDER FREE TRADE: CASE STUDIES OF ORANGE JUICE AND TOMATO PASTE IN THE WESTERN HEMISPHERE

The objective of this study was to determine the economic impact on the United States of removing tariff barriers on imports of concentrated orange juice and tomato paste from South America. The study highlighted an agglomeration model of industry location recognizing imperfect competition and increasing returns. The results were contrasted with those from a competitive model with conventional estimates of supply and demand elasticities. Because the assumptions of the models differed, the results also differed. The agglomeration model indicated that the United States would gain market share of production and processing with the removal of tariffs. In contrast, the competitive model indicated that the United States would lose market share in production and processing. According to the competitive model, US consumers would gain, producers would lose, and the government would lose from less tariff revenue, but the gains to consumers would offset losses elsewhere so that national income would rise. In South America, consumers would lose, producers would gain, and national incomes would rise. In the long run, countries would individually and collectively gain from freer trade in fruits and vegetables. Both models indicated that American production and processing of oranges and tomatoes would not be displaced by removing barriers to international trade.oranges, tomatoes, juice, paste, model, agglomeration, competitive, comparative advantage., Industrial Organization, International Relations/Trade,

[TiII] and [NiII] emission from the strontium filament of eta Carinae

We study the nature of the [TiII] and [NiII] emission from the so-called strontium filament found in the ejecta of eta Carinae. To this purpose we employ multilevel models of the TiII and NiII systems which are used to investigate the physical condition of the filament and the excitation mechanisms of the observed lines. For the TiII ion, for which no atomic data was previously available, we carry out ab initio calculations of radiative transition rates and electron impact excitation rate coefficients. It is found that the observed spectrum is consistent with the lines being excited in a mostly neutral region with an electron density of the order of $10^7$ cm$^{-3}$ and a temperature around 6000 K. In analyzing three observations with different slit orientations recorded between March~2000 and November~2001 we find line ratios that change among various observations, in a way consistent with changes of up to an order of magnitude in the strength of the continuum radiation field. These changes result from different samplings of the extended filament, due to the different slit orientations used for each observation, and yield clues on the spatial extent and optical depth of the filament. The observed emission indicates a large Ti/Ni abundance ratio relative to solar abundances. It is suggested that the observed high Ti/Ni ratio in gas is caused by dust-gas fractionation processes and does not reflect the absolute Ti/Ni ratio in the ejecta of \etacar. We study the condensation chemistry of Ti, Ni and Fe within the filament and suggest that the observed gas phase overabundance of TiComment: 14 paginas, 12 figure

Similarities and contrasts in tectonic and volcanic style and history along the Colorado plateaus-to-basin and range transition zone in Western Arizona: Geologic framework for tertiary extensional tectonics

The overall temporal and spatial relations between middle Tertiary volcanism and tectonism from the Basin and Range province onto the edge of the Colorado Plateaus province suggest that a single magnetic-tectonic episode affected the entire region more or less simultaneously during this period. The episode followed a post-Laramide (late Eocene through Oligocene) period of 25 million years of relative stability. Middle Tertiary volcanism did not migrate gradually eastward in a simple fashion onto the Colorado Plateau. In fact, late Oligocene volcanism appears to be more voluminous near the Aquarius Mountains than throughout the adjacent Basin and Range province westward to the Colorado River. Any model proposed to explain the cause of extension and detachment faulting in the eastern part of the Basin and Range province must consider that the onset of volcanism appears to have been approximately synchronous from the Colorado River region of the Basin and Range across the transition zone and onto the edge of the Colorado Plateaus

Existence and homogenization of the Rayleigh-B\'enard problem

The Navier-Stokes equation driven by heat conduction is studied. As a prototype we consider Rayleigh-B\'enard convection, in the Boussinesq approximation. Under a large aspect ratio assumption, which is the case in Rayleigh-B\'enard experiments with Prandtl number close to one, we prove the existence of a global strong solution to the 3D Navier-Stokes equation coupled with a heat equation, and the existence of a maximal B-attractor. A rigorous two-scale limit is obtained by homogenization theory. The mean velocity field is obtained by averaging the two-scale limit over the unit torus in the local variable