700 research outputs found

    Intraspecific Variation in Taxonomic Characteristics of the Mayfly \u3ci\u3ePotamanthus Myops\u3c/i\u3e (Walsh)

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    Data collected from an ecological study of the mayfly Potamanthus rnyops (Walsh) in Michigan showed intraspecific variability in taxonomic characteristics that have been employed by previous investigators for species separation. Nymphal dorsal maculation patterns varied considerably within a single population. Also, the ratio of mandibular tusk length to head length increased with successive nymphal instars. Certain adult taxonomic characteristics, particularly relative male imago eye size and distance of separation, were either too poorly defined or too variable to be conclusive in species identification

    Quantifying VOC emissions for the strategic petroleum reserve.

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    A very important aspect of the Department of Energy's (DOE's) Strategic Petroleum Reserve (SPR) program is regulatory compliance. One of the regulatory compliance issues deals with limiting the amount of volatile organic compounds (VOCs) that are emitted into the atmosphere from brine wastes when they are discharged to brine holding ponds. The US Environmental Protection Agency (USEPA) has set limits on the amount of VOCs that can be discharged to the atmosphere. Several attempts have been made to quantify the VOC emissions associated with the brine ponds going back to the late 1970's. There are potential issues associated with each of these quantification efforts. Two efforts were made to quantify VOC emissions by analyzing VOC content of brine samples obtained from wells. Efforts to measure air concentrations were mentioned in historical reports but no data have been located to confirm these assertions. A modeling effort was also performed to quantify the VOC emissions. More recently in 2011- 2013, additional brine sampling has been performed to update the VOC emissions estimate. An analysis of the statistical confidence in these results is presented here. Arguably, there are uncertainties associated with each of these efforts. The analysis herein indicates that the upper confidence limit in VOC emissions based on recent brine sampling is very close to the 0.42 ton/MMB limit used historically on the project. Refining this estimate would require considerable investment in additional sampling, analysis, and monitoring. An analysis of the VOC emissions at each site suggests that additional discharges could be made and stay within current regulatory limits

    Biogenic methane in shale gas and coal bed methane : a review of current knowledge and gaps

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    Biogenic CH4 generation has been observed in many shallow, low temperature shale gas basins and coal seams. The depletion of conventional resources and the increasing demand of natural gas for human consumption have spurred the development of so-called unconventional gas resources such as shale gas (SG) and coal-bed methane (CBM). Such unconventional systems represent the opportunity for the stimulation of biogenic CH4 generation. Biogenic CH4 in shale and coal is produced by anaerobic biodegradation of organic matter (OM): methanogenic Archaea represent only the final step of biogenic CH4 generation. Several communities of microorganisms are involved in the initial breakdown of complex geopolymers and the production of intermediate compounds used by methanogens. There are several key knowledge gaps on biogenic CH4 production in unconventional gas systems, such as the exact fraction of bioavailable OM, the microbial communities involved and how they can be stimulated to enhance microbial methanogenesis. Progress on biodegradation studies, isotopic signatures, as well as DNA analyses and proteomics could help unravel interactions within the syntrophic community involved in the methanogenic biodegradation of OM. Questions also remain regarding the environmental impact of unconventional gas production, such as water quality and the mobility of toxic metals and radionuclides. The answers to these questions might have implications for both recovery practices and a sustainable development of unconventional resources. This review summarises the current knowledge regarding biogenic CH4 in SG and CBM: from the nature of the rocks to the producing microbial community and the indicators of biogenic CH4, illustrating how these two environments show remarkably similar opportunities for the stimulation of biogenic CH4 generation

    Implicit and Explicit Values as a Predictor of Ethical Decision-Making and Ethical Behavior

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    The present study uses measures of implicit and explicit values to predict moral behaviors. Implicit value measures based on a word-fragment completion tasks were developed in this study to assess implicit values. Because values and moral processes are believed to operate at both explicit and implicit levels, it was hypothesized that both implicit and explicit values would predict moral behaviors. Results from a laboratory study show that both implicit and explicit values predicted actual moral behavior, consistent with dual process theories of morality. Chronic collective identity moderated the relation of both implicit and explicit values to ethical behavior. Theoretical and practical implications for the use of both explicit and implicit value measures in research and applied settings are discussed

    The TH1 cell lineage-determining transcription factor T-bet suppresses TH2 gene expression by redistributing GATA3 away from TH2 genes

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    Lineage-determining transcription factors (LD-TFs) drive the differentiation of progenitor cells into a specific lineage. In CD4+ T cells, T-bet dictates differentiation of the TH1 lineage, whereas GATA3 drives differentiation of the alternative TH2 lineage. However, LD-TFs, including T-bet and GATA3, are frequently co-expressed but how this affects LD-TF function is not known. By expressing T-bet and GATA3 separately or together in mouse T cells, we show that T-bet sequesters GATA3 at its target sites, thereby removing GATA3 from TH2 genes. This redistribution of GATA3 is independent of GATA3 DNA binding activity and is instead mediated by the T-bet DNA binding domain, which interacts with the GATA3 DNA binding domain and changes GATA3′s sequence binding preference. This mechanism allows T-bet to drive the TH1 gene expression program in the presence of GATA3. We propose that redistribution of one LD-TF by another may be a common mechanism that could explain how specific cell fate choices can be made even in the presence of other transcription factors driving alternative differentiation pathways

    Exercise intervention to prevent falls and enhance mobility in community dwellers after stroke: a protocol for a randomised controlled trial

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    Background: Stroke is the most common disabling neurological condition in adults. Falls and poor mobility are major contributors to stroke-related disability. Falls are more frequent and more likely to result in injury among stroke survivors than among the general older population. Currently there is good evidence that exercise can enhance mobility after stroke, yet ongoing exercise programs for general community-based stroke survivors are not routinely available. This randomised controlled trial will investigate whether exercise can reduce fall rates and increase mobility and physical activity levels in stroke survivors. Methods and design: Three hundred and fifty community dwelling stroke survivors will be recruited. Participants will have no medical contradictions to exercise and be cognitively and physically able to complete the assessments and exercise program. After the completion of the pre-test assessment, participants will be randomly allocated to one of two intervention groups. Both intervention groups will participate in weekly group-based exercises and a home program for twelve months. In the lower limb intervention group, individualised programs of weight-bearing balance and strengthening exercises will be prescribed. The upper limb/cognition group will receive exercises aimed at management and improvement of function of the affected upper limb and cognition carried out in the seated position. The primary outcome measures will be falls (measured with 12 month calendars) and mobility. Secondary outcome measures will be risk of falling, physical activity levels, community participation, quality of life, health service utilisation, upper limb function and cognition. Discussion: This study aims to establish and evaluate community-based sustainable exercise programs for stroke survivors. We will determine the effects of the exercise programs in preventing falls and enhancing mobility among people following stroke. This program, if found to be effective, has the potential to be implemented within existing community services. Trial registration: The protocol for this study is registered with the Australian New Zealand Clinical Trials Registry (ACTRN12606000479505)

    Iatrogenic Spinal Cord Injury Resulting From Cervical Spine Surgery.

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    STUDY DESIGN: Retrospective cohort study of prospectively collected data. OBJECTIVE: To examine the incidence of iatrogenic spinal cord injury following elective cervical spine surgery. METHODS: A retrospective multicenter case series study involving 21 high-volume surgical centers from the AOSpine North America Clinical Research Network was conducted. Medical records for 17 625 patients who received cervical spine surgery (levels from C2 to C7) between January 1, 2005, and December 31, 2011, were reviewed to identify occurrence of iatrogenic spinal cord injury. RESULTS: In total, 3 cases of iatrogenic spinal cord injury following cervical spine surgery were identified. Institutional incidence rates ranged from 0.0% to 0.24%. Of the 3 patients with quadriplegia, one underwent anterior-only surgery with 2-level cervical corpectomy, one underwent anterior surgery with corpectomy in addition to posterior surgery, and one underwent posterior decompression and fusion surgery alone. One patient had complete neurologic recovery, one partially recovered, and one did not recover motor function. CONCLUSION: Iatrogenic spinal cord injury following cervical spine surgery is a rare and devastating adverse event. No standard protocol exists that can guarantee prevention of this complication, and there is a lack of consensus regarding evaluation and treatment when it does occur. Emergent imaging with magnetic resonance imaging or computed tomography myelography to evaluate for compressive etiology or malpositioned instrumentation and avoidance of hypotension should be performed in cases of intraoperative and postoperative spinal cord injury
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