958 research outputs found
Quantitative Economic Evaluations of HIV-Related Prevention and Treatment Services: A Review
Dr. Holtgrave and colleagues at the CDC set forth an extensive taxonomy of HIV prevention and treatment services and review reports of efforts to subject some of those services to formal economic evaluation. They find few services thus far to have been so evaluated, no evaluation to have focused solely upon behavioral outcomes and most economic evaluations to lack formal quantitative analyses
Reevaluation of Wolfcampian Cyclothems in Northeastern Kansas: Significance of Subaerial Exposure and Flooding Surfaces
Ten cyclothems from the Wolfcampian of northeastern Kansas, including parts of the Council Grove and Chase Groups, were examined in detail with particular attention to discontinuity surfaces and paleosol development. These cyclothems are shown to be bounded by major discontinuities, or sequence boundaries, where marine limestones abruptly overlie paleosol profiles. Occurring within these cyclothemic sequences are prominent meter-scale cycles that are bounded by flooding surfaces, many of which overlie facies exhibiting evidence of subaerial exposure. They are developed within both the marine carbonate and shale intervals and variegated mudstone intervals of the cyclothems. These meter-scale cycles show a consistent carbonate-to-clastic pattern regardless of their stratigraphic position or component facies. Climate fluctuations within a generally monsoonal environment are determined to be the most likely forcing mechanism for the meter-scale cycles, with wetter climate phases resulting in the increased influx of terrigenous clastic sediment and drier climate phases favoring carbonate precipitation. Evidence of climate change at the scale of the cyclothemic sequences is also recognized in the studied interval. Cycles at both scales indicate that relative sea-level rise was associated with increasingly arid conditions and that sea-level fall was associated with an intensification of seasonal rainfall
Paleoecology of the Permian (Wolfcampian) Phylloid Alga Calcipatera from an In Situ Occurrence in Kansas, U.S.A.
In situ occurrences of the calcareous marine phylloid alga Calcipatera cottonwoodensis in the Permian Cottonwood Limestone Member (Beattie Limestone) occur in Greenwood County, Kansas, in association with platy algal packstones, which are the phylloid algal facies most commonly described in the literature. The in situ algal facies occurs in the upper 0.45 m of an exposure where it is overlain and underlain by algal packstones composed of transported and broken fragments of Calcipatera cottonwoodensis.
Calcipatera cottonwoodensis colonized coarse carbonate sands or carbonate mud substrates. During growth, carbonate mud accumulated in the cup-shaped thalli, and death followed when the rate of sedimentation exceeded the rate of algal growth. The three lithologies--substrate, cup-filling, and smothering--are easily recognized on polished surfaces.
Other members of the Calcipatera cottonwoodensis benthic community are Shamovella, encrusting and boring algae, foraminiferids, fenestrate and ramose bryozoans, brachiopods, bivalves, gastropods, trilobites, ostracodes, and echinoids. This occurrence and biotic association compares well with those described by Toomey (1976) and Wahlman (1988, 2002) from the Permian (Wolfcampian) of West Texas
Dependent and independent data in paleontology: Tools for the sedimentary modeler
The relationship of paleontology to sedimentologic and stratigraphic modeling can be viewed as dependent, independent, or some combination of the two. Independent paleontologic data are taxonomy based and include standard paleontologic techniques, such as biostratigraphy. Tremendous advances in temporal acuity have resulted from our ability to analyze standard biostratigraphic data bases through the different methodologies of quantitative biostratigraphy. Dependent paleontologic data result from biotic responses to externally mediated physical parameters (e.g., sea level, climate, sediment accumulation rate). Thus, for example, trace-fossil distribution can be used with care as a tool to help discern transgressive-regressive events. In addition, biotic event horizons (epiboles) can be used as indicators of temporal equivalency across complex depositional facies mosaics and thus serve as important markers for regional correlation
Dependent and independent data in paleontology: Tools for the sedimentary modeler
The relationship of paleontology to sedimentologic and stratigraphic modeling can be viewed as dependent, independent, or some combination of the two. Independent paleontologic data are taxonomy based and include standard paleontologic techniques, such as biostratigraphy. Tremendous advances in temporal acuity have resulted from our ability to analyze standard biostratigraphic data bases through the different methodologies of quantitative biostratigraphy. Dependent paleontologic data result from biotic responses to externally mediated physical parameters (e.g., sea level, climate, sediment accumulation rate). Thus, for example, trace-fossil distribution can be used with care as a tool to help discern transgressive-regressive events. In addition, biotic event horizons (epiboles) can be used as indicators of temporal equivalency across complex depositional facies mosaics and thus serve as important markers for regional correlation
Fusulinids from the Howe Limestone Member (Red Eagle Limestone, Council Grove Group) in Northeastern Kansas and Their Significance to the North American Carboniferous (Pennsylvanian)-Permian Boundary
Fusulinids from the Howe Limestone Member (upper part of the Red Eagle Limestone, lower part of the Council Grove Group) are described here for the first time. The Howe fauna is particularly significant because it represents the earliest fusulinids known to occur above the new conodont-based Carboniferous (Pennsylvanian)-Permian boundary at the Glenrock Limestone Member-Bennett Shale Member contact (Red Eagle Limestone) in northeastern Kansas. The Howe fusulinid assemblage is composed entirely of species of the genus Leptotriticites. The species L. hughesensis and L. glenensis were originally described from just beneath the new systemic boundary horizon in the Hughes Creek Shale Member and Glenrock Limestone Member, respectively. L. wetherensis is a species from the Stockwether Limestone Member of north-central Texas, which is thought to directly overlie the new systemic boundary in that region. L. gracilitatus is a species reported from below and above the boundary in west Texas and New Mexico. Therefore, the Howe Limestone Member fusulinid fauna is quite transitional in character. The first typical and diagnostic early Permian (Wolfcampian Series) fusulinids in the midcontinent section appear in steps through the stratigraphically higher Neva Limestone Member of the Grenola Limestone (Paraschwagerina kansasensis), and the Cottonwood and Morrill Limestone Members of the overlying Beattie Limestone (Schwagerina jewetti, S. vervillei). This offset of conodont and fusulinid faunal changes should be taken into account in regional and interregional biostratigraphic correlations of the new systemic boundary
Marine communities of a portion of the Wewoka formation (Pennsylvanian) in Hughes County, Oklahoma /
A study of growth and primary production of the seagrass, Posidonia Australis Hook F
Biomass and productivity of the seagrass Posidonia australis have been investigated (1977-78), at sites in Botany Bay (N.S.W.), Jervis Bay (N.S.W.), Port Hacking (N.S.W.) and Spencers Gulf (S.A.). Leaf biomass, which represented 20—25% of total biomass, ranged from 100 to 600 g dry weight per m2, and varied seasonally depending on water turbulence and growth rate. Leaf productivity was found to range from 0.6 to 5.2 g dry weight per m2 per day, depending on site and season. Rhizome and shoot production in Botany Bay was estimated to be 0.12 to 0.20 g dry weight per m2 per day. The turnover time (time to replace mean biomass) was found to be 93—117 days for leaves, and 11—19 years for the rhizome and shoot portions
Intergalactic Globular Clusters
We confirm and extend our previous detection of a population of intergalactic
globular clusters in Abell 1185, and report the first discovery of an
intergalactic globular cluster in the nearby Virgo cluster of galaxies. The
numbers, colors and luminosities of these objects can place constraints on
their origin, which in turn may yield new insights to the evolution of galaxies
in dense environments.Comment: 2 pages, no figures. Talk presented at JD6, IAU General Assembly XXV,
Sydney, Australia, July 2003, to appear in Highlights of Astronomy, Vol. 1
- …