549 research outputs found
String homology of spheres and projective spaces
We study a spectral sequence that computes the (mod 2) S^1-equivariant
homology of the free loop space LM of a manifold M (the "string homology" of
M). Using it and knowledge of the string topology operations on the homology of
LM, we compute the string homology of M when M is a sphere or a projective
space.Comment: 11 page
Beyond the first 25 years: The International AIDS Society and its role in the global response to AIDS
Dr. Pedro Cahn, International AIDS Society (IAS) President and Mr. Craig McClure, IAS Executive Director, provide their thoughts and analysis on the current and future role of the IAS as part of the global response to HIV/AIDS
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Heterogeneous Shallow-Shelf Carbonate Buildups in the Paradox Basin, Utah and Colorado: Targets for Increased Oil Production and Reserves Using Horizontal Drilling Techniques
The Paradox Basin of Utah, Colorado, Arizona, and New Mexico contains nearly 100 small oil fields producing from carbonate buildups within the Pennsylvanian (Desmoinesian) Paradox Formation. These fields typically have one to 10 wells with primary production ranging from 700,000 to 2,000,000 barrels (111,300-318,000 m{sup 3}) of oil per field and a 15 to 20 percent recovery rate. At least 200 million barrels (31.8 million m{sup 3}) of oil will not be recovered from these small fields because of inefficient recovery practices and undrained heterogeneous reservoirs. Several fields in southeastern Utah and southwestern Colorado are being evaluated as candidates for horizontal drilling and enhanced oil recovery from existing vertical wells based upon geological characterization and reservoir modeling case studies. Geological characterization on a local scale is focused on reservoir heterogeneity, quality, and lateral continuity, as well as possible reservoir compartmentalization, within these fields. This study utilizes representative cores, geophysical logs, and thin sections to characterize and grade each field's potential for drilling horizontal laterals from existing development wells. The results of these studies can be applied to similar fields elsewhere in the Paradox Basin and the Rocky Mountain region, the Michigan and Illinois Basins, and the Midcontinent region. This report covers research activities for the first half of the fourth project year (April 6 through October 5, 2003). The work included (1) analysis of well-test data and oil production from Cherokee and Bug fields, San Juan County, Utah, and (2) diagenetic evaluation of stable isotopes from the upper Ismay and lower Desert Creek zones of the Paradox Formation in the Blanding sub-basin, Utah. Production ''sweet spots'' and potential horizontal drilling candidates were identified for Cherokee and Bug fields. In Cherokee field, the most productive wells are located in the thickest part of the mound facies of the upper Ismay zone, where microporosity is well developed. In Bug field, the most productive wells are located structurally downdip from the updip porosity pinch out in the dolomitized lower Desert Creek zone, where micro-box-work porosity is well developed. Microporosity and micro-box-work porosity have the greatest hydrocarbon storage and flow capacity, and potential horizontal drilling target in these fields. Diagenesis is the main control on the quality of Ismay and Desert Creek reservoirs. Most of the carbonates present within the lower Desert Creek and Ismay have retained a marine-influenced carbon isotope geochemistry throughout marine cementation as well as through post-burial recycling of marine carbonate components during dolomitization, stylolitization, dissolution, and late cementation. Meteoric waters do not appear to have had any effect on the composition of the dolomites in these zones. Light oxygen values obtained from reservoir samples for wells located along the margins or flanks of Bug field may be indicative of exposure to higher temperatures, to fluids depleted in {sup 18}O relative to sea water, or to hypersaline waters during burial diagenesis. The samples from Bug field with the lightest oxygen isotope compositions are from wells that have produced significantly greater amounts of hydrocarbons. There is no significant difference between the oxygen isotope compositions from lower Desert Creek dolomite samples in Bug field and the upper Ismay limestones and dolomites from Cherokee field. Carbon isotopic compositions for samples from Patterson Canyon field can be divided into two populations: isotopically heavier mound cement and isotopically lighter oolite and banded cement. Technology transfer activities consisted of exhibiting a booth display of project materials at the annual national convention of the American Association of Petroleum Geologists, a technical presentation, a core workshop, and publications. The project home page was updated on the Utah Geological Survey Internet web site
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MAJOR OIL PLAYS IN UTAH AND VICINITY
Utah oil fields have produced over 1.2 billion barrels (191 million m{sup 3}). However, the 13.7 million barrels (2.2 million m{sup 3}) of production in 2002 was the lowest level in over 40 years and continued the steady decline that began in the mid-1980s. The Utah Geological Survey believes this trend can be reversed by providing play portfolios for the major oil-producing provinces (Paradox Basin, Uinta Basin, and thrust belt) in Utah and adjacent areas in Colorado and Wyoming. Oil plays are geographic areas with petroleum potential caused by favorable combinations of source rock, migration paths, reservoir rock characteristics, and other factors. The play portfolios will include: descriptions and maps of the major oil plays by reservoir; production and reservoir data; case-study field evaluations; summaries of the state-of-the-art drilling, completion, and secondary/tertiary techniques for each play; locations of major oil pipelines; descriptions of reservoir outcrop analogs; and identification and discussion of land use constraints. All play maps, reports, databases, and so forth, produced for the project will be published in interactive, menu-driven digital (web-based and compact disc) and hard-copy formats. This report covers research activities for the fourth quarter of the first project year (April 1 through June 30, 2003). This work included describing outcrop analogs to the Jurassic Nugget Sandstone and Pennsylvanian Paradox Formation, the major oil producers in the thrust belt and Paradox Basin, respectively. Production-scale outcrop analogs provide an excellent view, often in three dimensions, of reservoir-facies characteristics and boundaries contributing to the overall heterogeneity of reservoir rocks. They can be used as a ''template'' for evaluation of data from conventional core, geophysical and petrophysical logs, and seismic surveys. The Nugget Sandstone was deposited in an extensive dune field that extended from Wyoming to Arizona. Outcrop analogs are found in the stratigraphically equivalent Navajo Sandstone of southern Utah which displays large-scale dunal cross-strata with excellent reservoir properties and interdunal features such as oases, wadi, and playa lithofacies with poor reservoir properties. Hydrocarbons in the Paradox Formation are stratigraphically trapped in carbonate buildups (or phylloid-algal mounds). Similar carbonate buildups are exposed in the Paradox along the San Juan River of southeastern Utah. Reservoir-quality porosity may develop in the types of facies associated with buildups such as troughs, detrital wedges, and fans, identified from these outcrops. When combined with subsurface geological and production data, these outcrop analogs can improve (1) development drilling and production strategies such as horizontal drilling, (2) reservoir-simulation models, (3) reserve calculations, and (4) design and implementation of secondary/tertiary oil recovery programs and other best practices used in the oil fields of Utah and vicinity. During this quarter, technology transfer activities consisted of exhibiting the project plans, objectives, and products at a booth at the 2003 annual convention of the American Association of Petroleum Geologists. The project home page was updated on the Utah Geological Survey Internet web site
Sampling the Faraday rotation sky of TNG50: Imprint of the magnetised circumgalactic medium around Milky Way-like galaxies
Faraday rotation measure (RM) is arguably the most practical observational
tracer of magnetic fields in the diffuse circumgalactic medium (CGM). We sample
synthetic Faraday rotation skies of Milky Way-like galaxies in TNG50 of the
IllustrisTNG project by placing an observer inside the galaxies at a solar
circle-like position. Our synthetic RM grids emulate specifications of current
and upcoming surveys; the NRAO VLA Sky Survey (NVSS), the Polarisation Sky
Survey of the Universe's Magnetism (POSSUM), and a future Square Kilometre
Array (SKA1-mid) polarisation survey. It has been suggested that magnetic
fields regulate the survival of high-velocity clouds. However, there is only a
small number of observational detections of magnetised clouds thus far. In the
first part of the paper, we test conditions for the detection of magnetised
circumgalactic clouds. Based on the synthetic RM samplings of clouds in the
simulations, we predict upcoming polarimetric surveys will open opportunities
for the detection of even low-mass and distant clouds. In the second part of
the paper, we investigate the imprint of the CGM in the all-sky RM
distribution. We test whether the RM variation produced by the CGM is
correlated with global galaxy properties, such as distance to a satellite,
specific star formation rate, neutral hydrogen covering fraction, and accretion
rate to the supermassive black hole. We argue that the observed fluctuation in
the RM measurements on scales less than 1 degree, which has been considered an
indication of intergalactic magnetic fields, might in fact incorporate a
significant contribution of the Milky Way CGM.Comment: 18 pages, 11 figures, Accepted to MNRA
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CARBON AND OXYGEN ISOTOPIC ANALYSIS: BUG, CHEROKEE, AND PATTERSON CANYON FIELDS, SAN JUAN COUNTY, UTAH
Over 400 million barrels (64 million m{sup 3}) of oil have been produced from the shallow-shelf carbonate reservoirs in the Pennsylvanian (Desmoinesian) Paradox Formation in the Paradox Basin, Utah and Colorado. With the exception of the giant Greater Aneth field, the other 100 plus oil fields in the basin typically contain 2 to 10 million barrels (0.3-1.6 million m{sup 3}) of original oil in place. Most of these fields are characterized by high initial production rates followed by a very short productive life (primary), and hence premature abandonment. Only 15 to 25 percent of the original oil in place is recoverable during primary production from conventional vertical wells. An extensive and successful horizontal drilling program has been conducted in the giant Greater Aneth field. However, to date, only two horizontal wells have been drilled in small Ismay and Desert Creek fields. The results from these wells were disappointing due to poor understanding of the carbonate facies and diagenetic fabrics that create reservoir heterogeneity. These small fields, and similar fields in the basin, are at high risk of premature abandonment. At least 200 million barrels (31.8 million m{sup 3}) of oil will be left behind in these small fields because current development practices leave compartments of the heterogeneous reservoirs undrained. Through proper geological evaluation of the reservoirs, production may be increased by 20 to 50 percent through the drilling of low-cost single or multilateral horizontal legs from existing vertical development wells. In addition, horizontal drilling from existing wells minimizes surface disturbances and costs for field development, particularly in the environmentally sensitive areas of southeastern Utah and southwestern Colorado
Applying the Cry of Pain model as a predictor of deliberate self-harm in an early-stage adult male prison population
Purpose: Deliberate self-harming behaviour is more prevalent within the prison environment than in community samples, with those in the first weeks of imprisonment at greatest risk. Research in this area has been largely atheoretical and a unifying model may improve the predictability of assessment and the development of intervention approaches. This study applied William and Pollock’s (2001) Cry of Pain model as the theoretical process of deliberate self-harm in the early stages of imprisonment. Method: A prospective study of new arrivals at an adult male prison. Participants (n =181) completed questionnaires and it was hypothesised that the factors derived from the model (perceived stress, defeat, entrapment and absence of rescue factors) would be predictive of future deliberate self-harm. Prisoners with active psychosis and non-English speakers were excluded. All participants were followed up for four months for instances of self-harm. Eighteen participants engaged in self-harm during this period. Results: The Cry of Pain Model was supported in the analysis. Hierarchical binary logistic regression confirmed that all features of the model were supported as predictive of future self-harm in prison, even after controlling for previous self-harm, depression and hopelessness. Conclusion: The Cry of Pain model is supported as a predictive model for deliberate self-harm in prison. Suggestions are offered as to the impact on assessment and intervention directions in prison
Theileriosis in six dogs in South Africa and its potential clinical significance
Please read abstract in the article.http://www.jsava.co.zaam201
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