182 research outputs found

    Medical Malpractice - A Christian Ethical Perspective

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    Minimum Rim Width and Lamina Cribrosa Depth in Non-Glaucomatous and Glaucomatous U.S. Veterans

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    Purpose: Assess the utility of the MRW and lamina cribrosa depth measurements for detecting differences between non-glaucomatous and glaucomatous U.S. Veterans. Compare inter-eye differences of individuals with glaucoma. Method: 38 subjects were recruited per group: Group 1 included one eye of non-glaucomatous participants, and Group 2 included each qualifying eye of participants with glaucoma. Analysis compared Group 1 with the more affected eye only of Group 2 participants, and separately between the more and less affected eyes of group 2 participants. MRW measurements were obtained with Heidelberg Eye Explorer© (HEYEX). Average lamina cribrosa depths were measured manually utilizing HEYEX. Results: 26 subjects from Group 1 and 33 subjects from Group 2 were included. A significantly thinner MRW was found in glaucomatous eyes vs. non-glaucomatous eyes (210 µm vs. 309 µm; P \u3c .001). The normative database in HEYEX had an 85% sensitivity and 92% specificity to detect glaucomatous nerves. Among the 27 participants in Group 2 who had both eyes tested, eyes with more advanced visual field loss showed significantly thinner global MRW compared to fellow eyes (203 µm vs. 224 µm P = .03). Lamina cribrosa depths were non-significantly deeper in glaucomatous vs. non-glaucomatous eyes (476 µm vs. 429 µm P = .17). Conclusions: The MRW parameter differentiates between glaucomatous and non-glaucomatous optic nerves. Lamina cribrosa depths were non-significantly deeper in glaucomatous vs. non-glaucomatous participants. Post-hoc inter-eye data analysis suggested that inter-eye differences in gMRW values of glaucomatous eyes reflect asymmetric damage as correlated with the visual fiel

    Detection and removal of disturbance trends in tree-ring series for dendroclimatology

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    The authors thank The Carnegie Trust for the Universities of Scotland for providing funding for Miloš Rydval’s Ph.D. The Scottish pine network expansion has been an ongoing task since 2006, and funding must be acknowledged to the following projects: EU project “Millennium” (017008-2), Leverhulme Trust project “RELiC: Reconstructing 8000 years of Environmental and Landscape change in the Cairngorms (F/00 268/BG)”, and the NERC project “SCOT2K: Reconstructing 2000 years of Scottish climate from tree rings (NE/K003097/1)”. Kevin J. Anchukaitis was also supported by a grant for the US National Science Foundation (ARC-0902051).Nonclimatic disturbance events are an integral element in the history of forests. Although the identification of the occurrence and duration of such events may help to understand environmental history and landscape change, from a dendroclimatic perspective, disturbance can obscure the climate signal in tree rings. However, existing detrending methods are unable to remove disturbance trends without affecting the retention of long-term climate trends. Here, we address this issue by using a novel method for the detection and removal of disturbance events in tree-ring width data to assess their spatiotemporal occurrence in a network of Scots pine (Pinus sylvestris L.) trees from Scotland. Disturbance trends “superimposed” on the tree-ring record are removed before detrending and the climate signals in the precorrection and postcorrection chronologies are evaluated using regional climate data, proxy system model simulations, and maximum latewood density (MXD) data. Analysis of subregional chronologies from the West Highlands and the Cairngorms in the east reveals a higher intensity and more systematic disturbance history in the western subregion, likely a result of extensive timber exploitation. The method improves the climate signal in the two subregional chronologies, particularly in the more disturbed western sites. Our application of this method demonstrates that it is possible to minimise the effects of disturbance in tree-ring width chronologies to enhance the climate signal.PostprintPeer reviewe

    Mercury Accumulation in Tree Rings: Observed Trends in Quantity and Isotopic Composition in Shenandoah National Park, Virginia

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    Recent studies have shown that mercury (Hg) concentrations in tree rings have the potential to archive historical Hg exposure from local, regional, and global sources. The southeastern United States has received elevated Hg deposition, yet no studies have evaluated tree ring Hg in this region. Here, we quantify Hg accumulation and isotopic composition in tree rings collected in Shenandoah National Park, Virginia. Cores were collected from three individuals of three tree species—white oak (Quercus alba), northern red oak (Quercus rubra), and pitch pine (Pinus rigida)—within the northern, central, and southern areas of the Park (n = 27 cores). The cores were analyzed for Hg content in 10‐year increments, with some cores dating back to the early 1800s. Overall, tree ring Hg concentrations (ranging from below detection to 4.4 ng/g) were similar to other studies and varied between species, with pitch pine having higher concentrations than the deciduous species. The most notable feature of the tree ring Hg time series was a peak that occurred during the 1930s through 1950s, coinciding with the use of Hg at a local industrial facility. Atmospheric modeling indicates that potential emissions from the plant likely had a stronger impact on the southern region of the Park, consistent with the latitudinal gradient in tree ring Hg concentrations. Mass‐dependent and mass‐independent fractionation of Hg isotopes suggests contributions from both regional anthropogenic and local industrial sources during this period. This study demonstrates the potential usefulness of tree ring dendrochemistry for identifying historical sources of atmospheric Hg exposure.Key PointsTree ring mercury levels in Shenandoah National Park, Virginia, were similar to those measured in other North American forestsTree ring mercury peaked during the 1930s to 1950s, coinciding with mercury use at an industrial facility near the southern end of the ParkMercury isotopes suggest a local source at this time, demonstrating the potential of dendrochemistry to identify historical sourcesPlain Language SummaryFor many years scientists have used tree rings to reconstruct past climate. Increasingly, tree rings are being used to document the historical exposure of trees to pollutants. In this study, we cored trees in Shenandoah National Park, Virginia, dated the tree rings, and then measured the amount of mercury stored within decadal core increments. We were surprised to find that mercury levels peaked in the 1930s to 1950s, even though global mercury emissions continued to rise throughout the past century, mostly as a by‐product of energy production. Our findings suggest that the trees were exposed to a local pollutant source during this earlier time period, perhaps from a nearby industrial plant that used mercury in the production of rayon. By examining the chemistry of wood within tree rings, we can get a clearer picture of when and where human activities have affected air pollution over recent centuries.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153685/1/jgrg21576_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153685/2/jgrg21576.pd

    Multiscale mechanisms of cell migration during development: theory and experiment

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    Long-distance cell migration is an important feature of embryonic development, adult morphogenesis and cancer, yet the mechanisms that drive subpopulations of cells to distinct targets are poorly understood. Here, we use the embryonic neural crest (NC) in tandem with theoretical studies to evaluate model mechanisms of long-distance cell migration. We find that a simple chemotaxis model is insufficient to explain our experimental data. Instead, model simulations predict that NC cell migration requires leading cells to respond to long-range guidance signals and trailing cells to short-range cues in order to maintain a directed, multicellular stream. Experiments confirm differences in leading versus trailing NC cell subpopulations, manifested in unique cell orientation and gene expression patterns that respond to non-linear tissue growth of the migratory domain. Ablation experiments that delete the trailing NC cell subpopulation reveal that leading NC cells distribute all along the migratory pathway and develop a leading/trailing cellular orientation and gene expression profile that is predicted by model simulations. Transplantation experiments and model predictions that move trailing NC cells to the migratory front, or vice versa, reveal that cells adopt a gene expression profile and cell behaviors corresponding to the new position within the migratory stream. These results offer a mechanistic model in which leading cells create and respond to a cell-induced chemotactic gradient and transmit guidance information to trailing cells that use short-range signals to move in a directional manner

    Ornamental plants, 1985: a summary of research

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    Field transplant survival of Amelanchier liners produced by tissue culture / Daniel K. Struve and R. Daniel Lineberger -- An evaluation of strawdust - an alternative growing media / Elton M. Smith and Sharon A. Treaster -- Growth of container grown nursery stock produced in composted municipal sludge amended media / Elton M. Smith and Sharon A. Treaster -- Soil temperature effects on root regeneration of scarlet oak seedlings / Daniel K. Struve arid Bruno C. Moser -- Lighting Viburnum opulus 'Nanum' cuttings to increase winter survival / Elton M. Smith and Sharon A. Treaster -- Treatments of etiolated dormant rose shoots / Elton M. Smith and Sharon A. Treaster -- Evaluation of flowering crabapple susceptibility to apple scab in Ohio – 1984 / Elton M. Smith and Sharon A. Treaster -- Tolerance of azalea, cotoneaster, and euonymus to Devrinol, Goal, and Goal Combinations / Elton M. Smith and Sharon A. Treaster -- Micropropagation of chimeral african violets / R. Daniel Lineberger and Mark Druckenbrod -- capital requirements of overwintering structures for nurseries in Ohio - 1984 / Reed D. Taylor, Daryl T. Gillette, and Elton M. Smith -- annual fixed costs of overwintering plants in nurseries differentiated by type of structure for Ohio - 1984 / Daryl T. Gillette, Reed D. Taylor, and Elton M. Smith -- Comparative costs of overwintering plants in nurseries differentiated by system for Ohio - 1984 / Reed D. Taylor, Daryl T. Gillette, and Elton M. Smit

    Screening for Inhalational Anthrax Due to Bioterrorism: Evaluating Proposed Screening Protocols

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    Eleven known cases of bioterrorism-related inhalational anthrax (IA) were treated in the United States during 2001. We retrospectively compared 2 methods that have been proposed to screen for IA. The 2 screening protocols for IA were applied to the emergency department charts of patients who presented with possible signs or symptoms of IA at Inova Fairfax Hospital (Falls Church, Virginia) from 20 October 2001 through 3 November 2001. The Mayer criteria would have screened 4 patients (0.4%; 95% CI, 0.1%-0.9%) and generated charges of 1900 dollars. If 29 patients (2.6%; 95% CI, 1.7%-3.7%) with \u3eor=5 symptoms (but without fever and tachycardia) were screened, charges were 13,325 dollars. The Hupert criteria would have screened 273 patients (24%; 95% CI, 22%-27%) and generated charges of 126,025 dollars. In this outbreak of bioterrorism-related IA, applying the Mayer criteria would have identified both patients with IA and would have generated fewer charges than applying the Hupert criteria
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