Implications of subduction rehydration for earth's deep water cycle

The “standard model” for the genesis of the oceans is that they are exhalations from Earth’s deep interior continually rinsed through surface rocks by the global hydrologic cycle. No general consensus exists, however, on the water distribution within the deeper mantle of the Earth. Recently Dixon et al. [2002] estimated water concentrations for some of the major mantle components and concluded that the most primitive (FOZO) are significantly wetter than the recycling associated EM or HIMU mantle components and the even drier depleted mantle source that melts to form MORB. These findings are in striking agreement with the results of numerical modeling of the global water cycle that are presented here. We find that the Dixon et al. [2002] results are consistent with a global water cycle model in which the oceans have formed by efficient outgassing of the mantle. Present-day depleted mantle will contain a small volume fraction of more primitive wet mantle in addition to drier recycling related enriched components. This scenario is consis-tent with the observation that hotspots with a FOZO-component in their source will make wetter basalts than hotspots whose mantle sources contain a larger fraction of EM and HIMU components

Alleviating Pain: From Policy to Practice

No abstract available

Consolidation Study for Illinois Community Unit School Districts No. 10 and No. 20

The main purpose of this field study was to examine factors related to school consolidation in Lawrence County, Illinois. Two unit school districts-Community Unit School District No. 10 and No. 20-have been in operation since 1972 in southeastern Illinois. Both districts have full recognition by the Illinois State Board of Education and North Central Association of Colleges and Schools. In 1991-92, approximately 2,800 students attended kindergarten through twelfth grade in Lawrence County. However, financial considerations were the primary concerns of the schools/ operations. Due to revenue losses in farmland reassessment, property taxes and general state aid, Lawrence County administrators examined various methods to correct budgetary concerns. The researcher investigated consolidation as a cost-saving measure for Lawrence County citizens. Six major aspects of school operation were reviewed. Facilities, enrollment, curriculum, finances, transportation, and staff were considered important issues of consolidation. Interviews and reviews of research were the primary sources of information. It was anticipated that reorganization would be beneficial to the educational process of Lawrence County students. However, there was no evidence to support the benefits of consolidation. The facilities used were maintained and projected enrollment was steady. Cooperative sharing of academic and vocational courses was evident. Both districts balanced their budgets. The need for additional transportation and increased staff would be a result of consolidation. The final recommendation was to disregard consolidation in Lawrence County, Illinois. There was no advantage to the total educational program of the county students

STREAM WATER QUALITY MANAGEMENT: A STOCHASTIC MIXED-INTEGER PROGRAMMING MODEL

Water quality management under the watershed approach of Total Maximum Daily Load (TMDL) programs requires that water quality standards be maintained throughout the year. The main purpose of this research was to develop a methodology that incorporates inter-temporal variations in stream conditions through statistical distributions of pollution loading variables. This was demonstrated through a cost minimization mixed-integer linear programming (MIP) model that maintains the spatial integrity of the watershed problem. Traditional approaches for addressing variability in stream conditions are unlikely to satisfy the assumptions on which these methodologies are founded or are inadequate in addressing the problem correctly when distributions are not normal. The MIP model solves for the location and the maximum capacity of treatment plants to be built throughout the watershed which will provide the optimal level of treatment throughout the year. The proposed methodology involves estimation of parameters of the distribution of pollution loading variables from simulated data and use of those parameters to re-generate a suitable number of random observations in the optimization process such that the new data preserve the same distribution parameters. The objective of the empirical model was to minimize costs for implementing pH TMDLs for a watershed by determining the level of treatment required to attain water quality standards under stochastic stream conditions. The output of the model was total minimum costs for treatment and selection of the spatial pattern of the least-cost technologies for treatment. To minimize costs, the model utilized a spatial network of streams in the watershed, which provides opportunities for cost-reduction through trading of pollution among sources and/or least-cost treatment. The results were used to estimate the costs attributable to inter-temporal variations and the costs of different settings for the margin of safety. The methodology was tested with water quality data for the Paint Creek watershed in West Virginia. The stochastic model included nine streams in the optimal solution. An estimate of inter-temporal variations in stream conditions was calculated by comparing total costs under the stochastic model and a deterministic version of the stochastic model estimated with mean values of the loading variables. It was observed that the deterministic model underestimates total treatment cost by about 45 percent relative to the 97th percentile stochastic model. Estimates of different margin of safety were calculated by comparing total costs for the 99.9th percentile treatment (instead of an idealistic absolute treatment) with that of the 95th to 99th percentile treatment. The differential costs represent the savings due to the knowledge of the statistical distribution of pollution and an explicit margin of safety. Results indicate that treatment costs are about 7 percent lower when the level of assurance is reduced from 99.9 to 99 percent and 21 percent lower when 95 percent assurance is selected. The application of the methodology, however, is not limited to the estimation of TMDL implementation costs. For example, it could be utilized to estimate costs of anti-degradation policies for water quality management and other watershed management issues.Resource /Energy Economics and Policy,

Biodiversity of ants (Hymenoptera: Formicidae) in restored grasslands of different ages

The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Title from title screen of research.pdf file (viewed on August 27, 2007)Includes bibliographical references.Thesis (M.S.) University of Missouri-Columbia 2006.Dissertations, Academic -- University of Missouri--Columbia -- Entomology.Grasslands are an endangered ecosystem. Unfortunately, few studies monitoring the health of these grasslands have included arthropods, thus leaving out a vital biodiversity component. Ants have been proven to be reliable indicators of restoration success in some habitats. Literature regarding the benefits of ants in ecosystems is abundant; however, studies examining ant grassland ecology are limited. The availability of Conservation Reserve Program (CRP) land of different ages allowed us to examine differences in ant diversity (richness and abundance), species composition, and functional groups at different times since being restored as grasslands. Four sampling techniques were utilized (pitfall traps, litter samples, hand collection, and soil core sampling) on four different ages (0, 3, 7-8, 14-16 yrs) of grassland in east-central Missouri. Efficacy of sampling methods was also examined. A total of 18,743 ants were collected, representing 28 species in 16 genera. Ants were most abundant in older ages of CRP land. Species richness peaked in 7-8 yr fields. Some species showed patterns of being either early colonizers, late colonizers, or present in all field ages. The functional groups Cold Climate Specialists, Opportunists, Cryptic species, and Generalized Myrmicines (in descending order) dominated CRP land. Pitfall traps were the most effective sampling method. The results of this study provide baseline information on how ants establish on restored grassland in the CRP and provide information for future comparative studies

Investigations of the site and mechanisms of drug-induced reductions in the reabsorption of divalent cations by the kidney

Disturbances in electrolyte homeostasis are a frequent adverse side-effect of the administration of aminoglycoside antibiotics such as gentamicin, and the antineoplastic agent cis-platinum. The aims of this work were to further elucidate the site(s) and mechanism(s) by which these drugs may produce disturbances in the renal reabsorption of calcium and magnesium. These investigations were undertaken using a range of in vivo and in vitro techniques and models. Initially, a series of in vivo studies was conducted to delineate aspects of the acute and chronic effects of both drugs on renal electrolyte handling and to select and evaluate an appropriate animal model: subsequent investigations were focused on gentamicin. In a study of the acute and chronic effects of cis-platinum administration, there were pronounced acute changes in a variety of indices of nephrotoxic injury, including electrolyte excretion. Most effects resolved but there were chronic increases in the urinary excretion of calcium and magnesium. The renal response of three strains of rat (Fischer 344, Sprague-Dawley (SD), and Wistar) to a ranges of doses of gentamicin was also investigated. Drug administration produced substantially different responses between strains, in particular marked differences in calcium and magnesium excretion. The results suggested that the SD rat was an appropriately sensitive strain for use in further investigations. Acute infusion of gentamicin in the anaesthetised SD rat produced rapid, substantial increases in the fractional excretion of calcium and magnesium, while sodium and potassium output were unaffected, confirming previous results of similar experiments using F344 rats. Studies using lithium clearance measurements in the anaesthetised SD rat were undertaken to investigate the effects of gentamicin on proximal tubular calcium reabsorption. Lithium clearance was unaffected by acute gentamicin infusion, suggesting that the site of acute gentamicin-induced hypercalciuria may not be located in the proximal tubule. Inhibition of Ca2+ ATPase activity was investigated as a potential mechanism by which calcium reabsorption could be affected after aminoglycoside administration. In vitro, both Ca2+ ATPase and Na+/K+ ATPase activity could be similarly inhibited by the presence of aminoglycosides, in a dose-related manner. Whilst inhibition of Na+/K+ ATPase could be demonstrated biochemically after in vivo administration of gentamicin, there were no concurrent effects on Ca2+ ATPase activity, suggesting that inhibition of Ca2+ ATPase activity is unlikely to be a primary mechanism of aminoglycoside-induced reductions of calcium reabsorption. Histochemical studies could not discern inhibition of either Na+/K+ ATPase or Ca2+ ATPase activity after in vivo administration of gentamicin. Selection of renal cell lines for further investigative in vitro studies on the mechanisms of altered cation reabsorption was considered using MTT (3-(4,5,-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and Neutral Red cytotoxicity assays. The ability of LLC-PK1 and LLC-RK1 cell lines to correctly rank a series of nephrotoxic compounds with their known nephrotoxic potency in vivo was studied. Using these cell lines grown on semi-permeable inserts, alterations in the paracellular transport of 45Ca was investigated as a possible mechanism by which gentamicin could alter calcium reabsorption in vivo. Short term exposure (I h) of LLC-RK1 cells to gentamicin, via both cell surfaces, resulted in a reduction in paracellular permeability to both transepithelial 3H-mannitol and 45Ca fluxes. When LLC-RK1 cells were exposed via the apical surface only, similar dose-related reductions were seen to those observed when cells were exposed to the drug from both sides. Short-term basal exposure to gentamicin appeared to contribute less to the observed reductions in 3H-mannitol and 45Ca fluxes. Experiments investigating transepithelial movement of 45Ca and 3H-mannitol on LLC-PK1 cells after acute gentamicin exposure were inconclusive. Longer exposure (48 h) to gentamicin caused an increase in the permeability of the monolayer and a consequent increase in transepithelial 45Ca flux in the LLC-RK1 cell line; increases in permeability of LLC-PK1 cells to 45Ca and 3H-mannitol were not apparent under the same conditions. The site and mechanism at which gentamicin, in particular, alters calcium reabsorption cannot be definitively described from these studies. However, indirect evidence from lithium clearance studies suggests that the site of the lesion is unlikely to be located in the proximal tubule. The mechanism by which gentamicin exposure alters calcium reabsorption may be by reducing paracellular permeability to calcium rather than by altering active calcium transport processes

The half-lives of some short lived low Z nuclei formed by photonuclear reactions

The half-lives of several members of the mirror nuclei series have been measured, using improved scintillation counter detectors and a cycling apparatus which progams the synchrotron beam and several subsequent gated detectors in sequence repetitively. By the use of beta-ray energy discrimination, least squares fitting of decay curves, and by careful correction for background activities, the improved values listed in Table A were found