Space-group changes: a revision to a revision

The space group for the entry under the reference codes FEBMUU and FEBMUU01 in the Cambridge Structural Database (1992) should be further corrected to space group C2/c rather than P1(FEBMUU) or C2(FEBMUU01)

HST and Spitzer point source detection and optical extinction in powerful narrow-line radio galaxies

We present the analysis of infrared HST and Spitzer data for a sample of 13 FRII radio galaxies at 0.03<z<0.11 that are classified as narrow-line radio galaxies (NLRG). In the context of the unified schemes for active galactic nuclei (AGN), our direct view of the AGN in NLRG is impeded by a parsec-scale dusty torus structure. Our high resolution infrared observations provide new information about the degree of extinction induced by the torus, and the incidence of obscured AGN in NLRG. We find that the point-like nucleus detection rate increases from 25 per cent at 1.025$\mu$m, to 80 per cent at 2.05$\mu$m, and to 100 per cent at 8.0$\mu$m. This supports the idea that most NLRG host an obscured AGN in their centre. We estimate the extinction from the obscuring structures using X-ray, near-IR and mid-IR data. We find that the optical extinction derived from the 9.7$\mu$m silicate absorption feature is consistently lower than the extinction derived using other techniques. This discrepancy challenges the assumption that all the mid-infrared emission of NLRG is extinguished by a simple screen of dust at larger radii. This disagreement can be explained in terms of either weakening of the silicate absorption feature by (i) thermal mid-IR emission from the narrow-line region, (ii) non-thermal emission from the base of the radio jets, or (iii) by direct warm dust emission that leaks through a clumpy torus without suffering major attenuation.Comment: 18 pages, 7 figures, 8 tables, accepted for publication in MNRA

The Automated Array Assembly Task of the Low-cost Silicon Solar Array Project, Phase 2

An advanced process sequence for manufacturing high efficiency solar cells and modules in a cost-effective manner is discussed. Emphasis is on process simplicity and minimizing consumed materials. The process sequence incorporates texture etching, plasma processes for damage removal and patterning, ion implantation, low pressure silicon nitride deposition, and plated metal. A reliable module design is presented. Specific process step developments are given. A detailed cost analysis was performed to indicate future areas of fruitful cost reduction effort. Recommendations for advanced investigations are included

A Strategy for Fabrication Complex Structures via a Hybrid Manufacturing Process

The purpose of this paper is to introduce a strategy for fabricating complex structures via a hybrid manufacturing process. The Laser Aided Manufacturing Process (LAMP) lab at Missouri S&T has developed a hybrid process combining both a direct metal deposition process and a five-axis CNC milling. Accessibility is a difficulty when finish machining internal features. The concept is to pause the deposition process to finish machine an internal feature while it is still visible is one possible solution to this issue. However, this must be done in a manner that will not be spoiled when the deposition process continues. This paper discusses processing strategy, tool selection, and experimental validation of a technique to build complex structures via mid-process machining with an undercutting mill.Mechanical Engineerin

Processing experiments on non-Czochralski silicon sheet

A program is described which supports and promotes the development of processing techniques which may be successfully and cost-effectively applied to low-cost sheets for solar cell fabrication. Results are reported in the areas of process technology, cell design, cell metallization, and production cost simulation

Month-Timescale Optical Variability in the M87 Jet

A previously inconspicuous knot in the M87 jet has undergone a dramatic outburst and now exceeds the nucleus in optical and X-ray luminosity. Monitoring of M87 with the Hubble Space Telescope and Chandra X-ray Observatory during 2002-2003, has found month-timescale optical variability in both the nucleus and HST-1, a knot in the jet 0.82'' from the nucleus. We discuss the behavior of the variability timescales as well as spectral energy distribution of both components. In the nucleus, we see nearly energy-independent variability behavior. Knot HST-1, however, displays weak energy dependence in both X-ray and optical bands, but with nearly comparable rise/decay timescales at 220 nm and 0.5 keV. The flaring region of HST-1 appears stationary over eight months of monitoring. We consider various emission models to explain the variability of both components. The flares we see are similar to those seen in blazars, albeit on longer timescales, and so could, if viewed at smaller angles, explain the extreme variability properties of those objects.Comment: 4 pages, 3 figures, ApJ Lett., in pres

Identification of the water quality factors which prevent fingernail clams from recolonizing the Illinois River—phase III

TECHNICAL COMPLETION REPORT Project No. B-124-ILL Agreement No. 14-34-0001-0217The purpose of this research was to determine why fingernail clams have been unable to recolonize a 100-mile reach of the Illinois River where they were abundant prior to a die-off in the 1950's. Fingernail clams are major links in food chains leading from detritus and algae to higher level consumers valued by man, such as fish and water fowl. Three suspected toxicants and sediments from the reach where the die-off occurred were tested on intact fingernail clams (Musculium transversum) and gill preparations isolated from the clams. Concentrations of fluoride, lead and cadmium which caused a 50% reduction in the rate of beating of cilia on isolated clam gills, after 10 minutes of exposure (10-minute EC50), were 0.75, 0.02 and 0.06 mg/l , respectively. Mixtures of cadmium and fluoride were slightly more toxic to clam gills than predicted from results of bioassays with single toxicants. A fluoride concentration of 2.82 mg/l killed intact fingernail clams after eight weeks of exposure, while mortality in lesser concentrations and one higher concentration did not differ significantly from controls maintained in well water to which no fluoride had been added. Hence, the sub-lethal response exhibited by the gills is at least four times more sensitive than the lethal response. Maximum fluoride concentrations reported by the U.S. Geological Survey at two stations in the Illinois River ranged from .6 to .8 mg/l between 1979 and 1981, considerably below the concentrations which affected growth and survival of intact clams during 8-week exposures in our laboratory, but slightly above the level which affected isolated clam gills. A lead bioassay using intact clams was completed, but the results were ambiguous because concentration ranges in separate test chambers overlapped. In addition, insoluble lead precipitates accumulated in the test chambers, and the relative toxicity to clams of the soluble versus the insoluble lead was not determined. Until additional bioassays are completed, it is impossible to determine whether the maximum total lead concentrations of 0.40 mg/l which occurred in the Illinois River between 1979 and 1981 could have contributed to the failure of fingernail clams to recolonize the river. Fingernail clams exposed to sediments from lakes along the Illinois River suffered greater mortality after six weeks of exposure than clams exposed to sediment from the Mississippi River, although the differences were not statistically significant. The same sediments tested on clam gills produced statistically significant changes in ciliary beating rate and particle transport rates on the gills. Sediments from the upstream lakes cause a greater depression in the particle transport rate and ciliary beating rates than sediments from downstream lakes. In addition, sediments from the lake furthest upstream caused a drastic change from the normal metachronal beating pattern to an atypical synchronous pattern. The results with the gill assay suggest that sediments in the Illinois River contain unidentified toxic factors and that sediments in the upper river, closer to the metropolitan areas of Joliet and Chicago, are more toxic than sediments further downstream. These results should be confirmed by additional tests with intact clams, including field tests with caged organisms. Parallel chemical analyses and bioassays of extracts from the sediments should be performed to identify the toxic components.U.S. Department of the InteriorU.S. Geological SurveyOpe

Development of toxicity indices for assessing the quality of the Illinois River

Individual toxicant concentrations in the Illinois River were expressed as fractions of their 96-hr LC50 values to bluegills, yielding their component toxicities in bluegill toxic units (BGTU’s). A solution having a toxicity of 1.0 BGTU was defined as being lethal to 50 percent of the bluegills exposed to it for 96 hr. River toxicants included aldrin, undissociated ammonia (ammonia₍ᵤ₎), arsenic, cadmium, hexavalent and trivalent chromium, copper, cyanide, fluoride, linear alkylate sulfonate (LAS), lead, mercury, phenols, and zinc. Component toxicities at different locations on the river were summed to produce the toxicity index, or total toxicity, of the river. Preliminary mean toxicity indices developed from previously published data during 1972 and 1973 ranged from 0.045 to 0.168 BGTU's, on the Illinois and Des Plaines rivers. However, maximum component toxicities of ammonia₍ᵤ₎ and cyanide during this period reached 0.630 and 0.467 BGTU's, respectively. LAS, copper, fluoride, and zinc also contributed to the preliminary river toxicity indices. Mean toxicity indices developed during field tests, in which bluegills were exposed directly to river water, and the lack of mortality at these tests, indicated that the Illinois River is not normally acutely toxic to fish. The 96-hr LC50 values of ammonia₍ᵤ₎ and LAS to bluegills were found to be 1.65 and 6.5 mg/liter, respectively, using continuous-flow bioassays with dilution water similar in hardness, alkalinity and pH to Illinois River water.U.S. Department of the InteriorU.S. Geological SurveyOpe