Inference of relativistic electron spectra from measurements of inverse compton radiation

The inference of relativistic electron spectra from spectral measurement of inverse Compton radiation is discussed for the case where the background photon spectrum is a Planck function. The problem is formulated in terms of an integral transform that relates the measured spectrum to the unknown electron distribution. A general inversion formula is used to provide a quantitative assessment of the information content of the spectral data. It is shown that the observations must generally be augmented by additional information if anything other than a rudimentary two or three parameter model of the source function is to be derived. It is also pointed out that since a similar equation governs the continuum spectra emitted by a distribution of black-body radiators, the analysis is relevant to the problem of stellar population synthesis from galactic spectra.     

Coalification of organic matter in coal balls of the Pennsylvanian (upper Carboniferous) of the Illinois Basin, United States

An evaluation was made of the degree of coalification of two coal balls from the Illinois Basin of the Pennsylvanian (upper Carboniferous) of the United States. Previous interpretations are mainly misleading and contradictory, primarily because of the assumption that the brown color and exceptional cellular and subcellular preservation typical of American coal balls imply chemical preservation of cellulose and lignin, the primary components of peat. Xylem tissue from a medullosan seed fern contained in a coal ball and the coal attached to the coal ball from the Calhoun coal bed, Mattoon Formation, Illinois, was analyzed by elemental, petrographic, and nuclear magnetic resonance (NMR) techniques to determine the degree of coalification. The NMR and elemental data indicate the lack of cellulose and lignin and a probable rank of high-volatile C bituminous coal. These data corroborate data for a coal ball from the Herrin (No. 6) coal bed (Carbondale Formation, Middle Pennsylvanian) and support our hypothesis that the organic matter in coal balls of the Pennsylvanian strata of the United States is coalified to about the same degree as the surrounding coal. Data presented show a range of lower reflectances for xylem tissue and vitrinite in the analyzed coal balls compared with vitrinite in the attached coal.The data reported indicate that physical preservation of organic matter in coal balls does not imply chemical preservation. Also our study supports the hypothesis that compactional (static load) pressure is not a prerequisite for coalification up to a rank of high-volatile C bituminous coal.A whole-rock analysis of the Calhoun coal ball indicates a similarity to other carbonate coal balls from the United States. It consists primarily of calcium carbonate and 1–2% organic matter; silica and alumina together make up less than 0.5%, indicating the lack of minerals such as quartz and clays.     

Resin rodlets in shale and coal (Lower Cretaceous), Baltimore Canyon Trough

Rodlets, occurring in shale and coal (uppermost Berriasian to middle Aptian, Lower Cretaceous), were identified from drill cuttings taken from depths between 9330 ft (2844 m) and 11, 460 ft (3493 m) in the Texaco et al., Federal Block 598, No. 2 well, in the Baltimore Canyon Trough. Under the binocular microscope, most of the rodlets appear black, but a few are reddish brown, or brownish and translucent on thin edges. They range in diameter from about 0.4 to 1.7 mm and are commonly flattened. The rodlets break with a conchoidal fracture, and some show an apparent cellular cast on their longitudinal surfaces. When polished and viewed in reflected light, the rodlets appear dark gray and have an average random reflectance of less than 0.1% whereas mean maximum reflectances are 0.48–0.55% for vitrinite in the associated shale and coal. These vitrinite reflectances indicate either subbituminous A or high-volatile C bituminous coal. The rodlets fluoresce dull gray yellow to dull yellow. The scanning electron microscope (SEM) and light microscope reveal the presence of swirl-like features in the rodlet interiors. Minerals associated with the rodlets occur as sand-size grains attached to the outer surface, as finely disseminated interior grains, and as fracture fillings. Electron microprobe and SEM-energy-dispersive X-ray (EDX) anlayses indicate that the minerals are dominantly clays (probably illite and chlorite) and iron disulfide; calcium carbonate, silicon dioxide, potassium aluminum silicate (feldspar), titanium dioxide, zinc sulfide, and iron sulfate minerals have been also identified. The rodlets were analyzed directly for C, H, N, O, and total S and are interpreted as true resins on the basis of C and H contents that range from 75.6 to 80.3 and from 7.4 to 8.7 wt. % (dry, ash-free basis), respectively. Elemental and infrared data support a composition similar to that of resinite from bituminous coal. Elements determined to be organically associated in the rodlets include S (0.2–0.5 wt.%), Cl (0.03–0.1 wt.%), and Si (0.05–0.08 wt.%). The ash content of the resin rodlets ranges from 4 to 24 wt.% and averages 12 wt.%. Total sulfur contents range from 1.7 to 3.6 wt.%. Resins of fossil plants are known to have little or no sulfur and ash; therefore, these data and the presence of minerals in fractures indicate that most of the sulfur and mineral matter were introduced into the resin partly or wholly after the time of brittle fracture of the resin. The probable source of the resin rodlets is fossil pinaceous conifer cones, which are known to have resin canals as much as 2400 μm in diameter.     

Phylogenetic Problems in Polynesian Simuliidae (Diptera: Culicomorpha): A progress report

As a basis for eventual control of the vicious anthropophilic and ornithophilic simuliid females of the Marquesas Islands, a taxonomic revision of Polynesian Simuliidae is in progress. Cytotaxonomic studies reveal two simuliid species in Rarotonga, Cook Islands; nine species in Tahiti, Society Islands, and two in the Marquesas Islands. A cytophylogeny is now available. Polynesian Simuliidae are unique in possessing heterogametic females. A reconstructed phylogeny, based mainly on morphological character states of larvae and pupae, agrees well with the cytophylogeny. One of the new species which is closely related to Simulium oviceps Edwards has larvae with highly reduced, non-functional cephalic fans. Ages of the Polynesian islands are discussed in relation to possible dispersal of Simuliidae into Polynesia.     

An evaluation of garnet-clinopyroxene geothermometry in granulites

Four new formulations of the garnet-clinopyroxene geothermometer (Ellis and Green 1979; Ganguly 1979; Saxena 1979; Dahl 1980) have been evaluated in the Adirondacks and five other granulite terranes using results from 94 mineral pairs. The Saxena and Ganguly formulations give temperatures that are generally 100–150° C above those constrained by phase equilibria and other independent thermometry while the empirical calibration of Dahl gives widely scattered, erratic results. Despite some scatter in the data, the Ellis and Green calibration appears to be more accurate and precise than the others and is the most useful garnet-clinopyroxene thermometer currently available for quantitative thermometry in granulites. All four formulations are sensitive to large variations (>70–80° C) in temperature suggesting that problems with accuracy and precision can be improved with further refinement of model-based aspects of the thermometers.     

Geochemistry and evolution of the fuego volcanic complex, Guatemala

Four closely spaced vents along a fissure make up the Fuego and Acatenango volcanic centers in western Guatemala. The Fuego complex is composed of the Fuego and Meseta vents, but historic activity has consisted exclusively of high-Al₂O₃ basalts from the Fuego vent. The Meseta vent is inactive and deeply exposed. Prehistoric lavas from Fuego and Meseta are generally more silicic than historic Fuego lavas, but all the rocks form a single coherent geochemical variation pattern. Major element chemistry of these rocks is consistent with plagioclase, olivine, augite, and magnetite (POAM) fractionating from high-Al₂O₃ basalt. Separate batches of magma can be recognized from trace-element data throughout the history of the Fuego complex. This suggests that closed-system, POAM fractionation of distinct magma bodies occurs at Fuego. Trace-element data requires that deep fractionation of olivine, clinopyroxene, and perhaps magnetite from primary olivine tholeiite occurs before arrival of new magma into the shallow (8–16 km) magma chamber at Fuego. Migration of activity from Meseta to Fuego along the fissure is correlated with the change towards more mafic compositions at Fuego. The shift of the vents may have resulted in shorter repose periods and less time for fractionation before eruption. A minimum age of 17,000 years was required to build the Fuego complex.The andesitic rocks from the adjacent, larger composite volcanoes of Acatenango and Agua have higher incompatible element concentrations, different incompatible element ratios, and lower CaO, Na₂O, and Al₂O₃ contents than Fuego's lavas. We believe the magmatic evolution of Acatenango and Agua is much more complex than Fuego.     

Cladding influence on dynamics response of tall buildings

Precast concrete panels form attractive facades for steel frame buildings and are generally regarded as non-structural by structural engineers. However, panels have been found to add lateral stiffness until their capacity or that of their connections is exceeded. Consequently, the computed dynamic response based on a model of the structural framing alone may be quite different from that experienced by the actual structure. As a case study, the influence of precast concrete panels on lateral and torsional stiffness of a 25-storey building was investigated. The effect of cladding on dynamic properties and linear seismic response was explored by varying panel stiffness. Cladding stiffness was added to the bare frame model until analytical frequency values matched vibration test results. Then, using the cladding stiffness values obtained, an accidental eccentricity between centres of mass and rigidity at each floor level was imposed and linear seismic response computed. Torsional response effects were increased substantially. Finally, a modified cladding panel connection was developed based on previously-reported studies for panelized construction. The influence of the proposed connection on overall structural response was determined for different ground motion inputs.