An evaluation of grazing-incidence optics for neutron imaging

The focusing capabilities of neutron imaging optics based on the Wolter-1 geometry have been successfully demonstrated with a beam of long wavelength neutrons with low angular divergence. A test mirror was fabricated using an electroformed nickel replication process at Marshall Space Flight Center. The neutron current density gain at the focal spot of the mirror is found to be at least 8 for neutron wavelengths in the range from 6 to 20 Å. Possible applications of the optics are briefly discussed.     

Bidirectional reflectance effects in NOAA AVHRR data

The bidirectional reflectance effects in NOAA AVHRR data have been investigated for forest and pasture sites in New Zealand. The impact of surface anisotropy has been examined for channel 1, channel 2, and the derived Normalized Difference Vegetation Index (NDVI) over a 14-day period in the southern hemisphere summer of 1992/1993. Results show a bidirectional effect which persists through atmospheric correction processing and the generation of the NDVI. Comparison is made with previously published results and models, which show consistency for this limited data set.     

Optimization of a hydrodynamic cavitation reactor using salicylic acid dosimetry

In the present work, optimization of a hydrodynamic cavitation reactor, for maximizing the extent of hydroxyl radical generation, has been investigated using salicylic acid as a dosimeter. The effect of different operating parameters such as inlet pressure into the reactor, shape of the orifice, and concentration of salicylic acid employed was investigated where the extent of hydroxyl radical generation was quantified in terms of concentration of the hydroxylated products 2,5- and 2,3-dihydroxybenzoic acid. With an upstream pressure of <100 psi no hydroxyl radicals were produced but excellent results were obtained with a small circular nozzle at 4000 psi and a salicylate concentration of 750 ppm. The use of a combination of ultrasound along with hydrodynamic cavitation is also reported for the first time and results in a 15% improvement in the hydroxyl radical generation when the distance between the orifice and transducer is 5–10 mm.     

Beyond color: Modifiers and additives that affect appearance

In today's globally competitive market, product distinction is a key to success. Therefore, the ability to produce unique and appealing special effects becomes a powerful marketing tool for savvy manufacturers of plastic and other parts. High shelf-appeal not only positions a product to attract the eye of the consumer, but also supports the impression that a product is of higher quality, a more playful or elegant design, or represents the latest that technology has to offer. When it comes to special effects, the buying public is insatiable and market demand is hindered only by the imagination of manufacturers and consumers. The ability of current color technology to support this demand requires that additive suppliers, color formulators, and plastics processors work in close partnership. This paper surveys the development of traditional and newer special effects technologies and describes some of the challenges encountered in developing them.     

The sympathetic nervous system''s role in regulating blood pressurevariability

This article focuses on how sympathetic nerve activity (SNA) contributes to the variability seen in blood pressure. Specifically, it examines the following questions: why do oscillations occur at certain frequencies, why do only certain frequencies of oscillations in SNA induce oscillations in the vasculature, and what may be the functional purpose of these oscillations