Morphology and structure of the Lomonosov Ridge, Arctic Ocean

The Lomonosov Ridge is a band of continental crust that stretches across the Arctic Ocean and separates the Mesozoic Amerasian Basin from the Cenozoic Eurasian Basin. From about 87°N north of Greenland across the Pole to about 86°N, the Lomonosov Ridge is a single high-standing blocky ridge with minimum depths of ~ 950 - 1400 m. South of 86°N on the Siberian side, the ridge breaks up into a series of ridges spread over a width of about 200 km. In this region a high-standing blocky ridge with minimum depths of ~ 650 - 1400 m bounds the Eurasian Basin and continues to the Siberian continental margin. This ridge is continuous with the single ridge making up the Lomonosov Ridge toward North America and is the former outermost continental shelf of Eurasia bounding the Amerasian Basin. The Eurasian Basin margin of the Lomonosov Ridge consists of a series of rotated fault blocks stepping down to the basin that result from nearly orthogonal rifting to form the Eurasian Basin. No rotated fault blocks are observed on the Amerasian Basin margin of the Lomonosov Ridge. On the Amerasian Basin side, Marvin Spur, a linear ridge separated from Lomonosov Ridge by a deep basin, parallels Lomonosov Ridge on the North American side of the pole. At the bend in the Lomonosov Ridge near the North Pole, Marvin Spur continues along strike across the Makarov Basin. South of 86°N toward Siberia, a continuous outer ridge makes up the Amerasian Basin edge of the Lomonosov complex with a series of basins and ridges between it and the former Eurasian shelf. The outer ridge marks an abrupt boundary between the Lomonosov Ridge complex and the apparently oceanic crust of the Makarov Basin. The outer ridge and Marvin Spur very closely follow small circles about a pole located on the Mackenzie delta. The observed structure on the Amerasian Basin side of the Lomonosov Ridge is analogous to that observed at well-studied shear margins and supports rotational models for the development of the Amerasian Basin

Bridging the Great Divide Between Theoretical and Empirical Management Research

Management research places a great premium on theory development. Despite this emphasis, concerns have been expressed regarding the extent to which management theories are tested in empirical research. This article reviews evidence concerning the connections between theoretical and empirical management research and reports an investigation that examines the correspondence between the propositions presented in 20 highly cited theoretical articles and the hypotheses stated in 361 empirical articles that cite the theories. Results indicate that the vast majority of theoretical propositions are not translated into empirical hypotheses, indicating a great divide between theoretical and empirical management research. Implications of these results are discussed, and potential solutions are offered

The Effect of Turfgrass Maintenance on Surface-Water Quality in a Suburban Watershed, Inner Blue Grass, Kentucky

Nutrients and pesticides applied during routine maintenance or establishment of turfgrass could result in nonpoint-source pollution. Nutrient and pesticide concentrations in water exiting a turfgrass management area in the Sinking Creek watershed, a suburban watershed in the Inner Blue Grass Region of central Kentucky, were monitored. This watershed was selected because it contains multiple land uses: agricultural, residential, and recreational (golf course). A survey was conducted to determine the extent to which lawn-care products are used in the residential sector of the watershed. For the golf-course portion, the golf-course superintendent recorded chemical application daily. Runoff from the golf course was sampled in 1993 where the stream exits the golf-course property. Sinking Creek was sampled upstream and downstream of the Tashamingo subdivision from April through October 1996 and January through February 1997. Weekly grab samples and three storm sample sequences (spring, summer, and fall) were analyzed to determine pesticide and nutrient concentrations. The analysis results revealed that few instances of pesticide concentrations in Sinking Creek exceeded minimum detectable levels and none exceeded the U.S. Environmental Protection Agency drinking-water limits during the sampling period. The herbicide 2,4-D was detected in Sinking Creek at both sample locations. In addition to 2,4-D, the insecticide chlorpyrifos was detected at the golf-course exit. Increases in pesticides and nutrients in Sinking Creek coincided with spring application of turfgrass chemicals in the suburban portion of the watershed. Concentrations of nitrogen and phosphorus were low and similar to what would be expected for the land use

The Gakkel Ridge: Bathymetry, gravity anomalies, and crustal accretion at extremely slow spreading rates

The Gakkel Ridge in the Arctic Ocean is the slowest spreading portion of the global mid-ocean ridge system. Total spreading rates range from 12.7 mm/yr near Greenland to 6.0 mm/yr where the ridge disappears beneath the Laptev Shelf. Swath bathymetry and gravity data for an 850 km long section of the Gakkel Ridge from 5°E to 97°E were obtained from the U.S. Navy submarine USS Hawkbill. The ridge axis is very deep, generally 4700–5300 m, within a well-developed rift valley. The topography is primarily tectonic in origin, characterized by linear rift-parallel ridges and fault-bounded troughs with up to 2 km of relief. Evidence of extrusive volcanic activity is limited and confined to specific locations. East of 32°E, isolated discrete volcanoes are observed at 25 - 95 km intervals along the axis. Abundant small-scale volcanism characteristic of the Mid-Atlantic Ridge (MAR) is absent. It appears that the amount of melt generated is insufficient to maintain a continuous magmatic spreading axis. Instead, melt is erupted on the seafloor at a set of distinct locations where multiple eruptions have built up central volcanoes and covered adjacent areas with low relief lava flows. Between 5°E and 32°E, almost no volcanic activity is observed except near 19°E. The ridge axis shoals rapidly by 1500 m over a 30 km wide area at 19°E, which coincides with a high-standing axis-perpendicular bathymetric high. Bathymetry and side scan data show the presence of numerous small volcanic features and flow fronts in the axial valley on the upper portions of the 19°E along-axis high. Gravity data imply up to 3 km of crustal thickening under the 19°E axis-perpendicular ridge. The 19°E magmatic center may result from interaction of the ridge with a passively imbedded mantle inhomogeneity. Away from 19°E, the crust appears thin and patchy and may consist of basalt directly over peridotite. The ridge axis is continuous with no transform offsets. However, sections of the ridge have distinctly different linear trends. Changes in ridge trend at 32°E and 63°E are associated with a set of bathymetric features that are very similar to each other and to inside/outside corner complexes observed at the MAR including high-standing ‘‘inside corner’’ ridges, which gravity data show to be of tectonic rather than magmatic origin

Microbead models in glaucoma

The sustained and moderate elevation of intraocular pressure, which can be initiated at precise time points, remains the cornerstone of research into the mechanisms of glaucomatous retinal damage. We focus on the use of microbeads to block the outflow of aqueous following anterior chamber injection in a range of animals (mouse, rat and primate). We describe some of the most commonly used parameters and present guidance on injection technique and bead manipulation to facilitate the successful generation of experimental glaucoma

Reimbursement for Emergency Department Electrocardiography and Radiograph Interpretations: What Is It Worth for the Emergency Physician

Background: Physician reimbursement laws for diagnostic interpretive services require that only those services provided contemporaneously and /or contribute directly to patient care can be billed for. Despite these regulations, cardiologists and radiologists in many hospitals continue to bill for ECG and plain film diagnostic services performed in the emergency department (ED). The reimbursement value of this care, which is disconnected in time and place from the ED patient encounter, is unknown. In a California community ED with a 32,000 annual census, the emergency physicians (EPs) alone, by contract, bill for all ECG readings and plain film interpretations when the radiologists are not available to provide contemporaneous readings.Objectives: To determine the impact of this billing practice on actual EP reimbursement we undertook an analysis that allows calculation of physician reimbursement from billing data.Methods: An IRB-approved analysis of 12 months of billing data cleansed of all patient identifiers was undertaken for 2003. From the data we created a descriptive study with itemized breakdown of reimbursement for radiograph and ECG interpretive services (procedures) and the gross resultant physician income.Results: In 2003 EPs at this hospital treated patients during 32,690 ED visits. Total group income in 2003 for radiographs was $173,555 and$91,025 for ECGs, or $19/EP hour and$6/EP hour respectively. For the average full-time EP, the combined total is $2537/month or$30,444 per annum, per EP. This is $8/ED visit (averaged across all patients).Conclusion: As EP-reimbursement is challenged by rising malpractice premiums, uninsured patients, HMO contracts, unfunded government mandates and state budgetary shortfalls, EPs are seeking to preserve their patient services and resultant income. They should also be reimbursed for those services and the liability that they incur. The reimbursement value of ECGs and plain film interpretations to the practicing EP is substantial. In the ED studied, it represents$30,444 gross income per full-time EP annually. Plain film interpretation services produce three times the hourly revenue of ECG reading at the hospital studied.[WestJEM. 2009;10:178-183.

Validating a Vegetative Filter Strip Performance Model

Vegetative filter strips (VFS) reduce losses of nutrients, solids, and other materials from land area treated with fertilizers and manures. A number of models are available that simulate nutrient and sediment transport in VFS. While VFS effectiveness is considered to depend on lengths of pollutant source area and VFS areas, few published studies have tried to validate these models using variable pollutant source area and VFS area. The objective of this study was to validate an event-based nutrient transport model (Chaubey et al., 1995) that simulates soluble nutrient transport in VFS. This model links three sub-models: modified Green-Ampt infiltration, non-linear kinematic wave overland flow routing, and a nutrient transport component. The nutrient transport component considers infiltration as the only mechanism of pollutant removal from runoff. Data from a field plot experiment were used to validate the model. The model was executed using an uncalibrated runoff component, a calibrated runoff component, and measured runoff. The concentrations of parameters entering the VFS from three different poultry litter application lengths (6.1, 12.2, and 18.3 m) were not significantly different. However, predicted concentrations at subsequent lengths were different for all the three poultry litter application lengths. This finding was consistent with the observed data. Model execution with the uncalibrated runoff component, calibrated runoff component, and measured runoff underpredicted concentrations and mass transport at various locations along the length of the VFS. Underprediction of concentration was judged to be the reason for underprediction of mass transport. The agreement between the observed and predicted concentrations and mass transport, however, improved when runoff predictions from the calibrated runoff component and measured runoff were used. This suggests that accurate prediction of infiltration and runoff is critical for accurate prediction of concentration mass transport. Furthermore, since concentration was underpredicted even when measured runoff was used, this study suggests that the nutrient transport component might be improved, possibly by including nutrient removal mechanisms other than infiltration

Development of Wave Energy Converters at Ocean Power Technologies (Extended Abstract)

This abstract contains information relevant to the use of wave information for naval operations, education, and alternative energy technologies, and was used, along with the Session Presentation, to facilitate discussion during Session 1 (the use of wave measurements to support operations)