145 research outputs found

    Geologic Characterization, Hydrologic Monitoring, and Soil-Water Relationships for Landslides in Kentucky

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    Complex spatial and temporal variables control the movement of water through colluvial soils in hillslopes. Some of the factors that influence soil-moisture fluctuation are soil type, thickness, porosity and permeability, and slope morphology. Landslide-characterization and field-monitoring techniques were part of a method to connect hydrologic and geotechnical data in order to monitor long-term hydrologic conditions in three active landslides in Kentucky, establish hydrologic relationships across the slope, and analyze specific soil-water relationships that can predict shear strength. Volumetric water content, water potential, and electrical conductivity were measured between October 2015 and February 2019. The duration and magnitude of drying and wetting within the soil varied for each slope location and soil depth, suggesting that differences in slope morphology, soil texture, and porosity influence the water-infiltration process, as well as shear strength and general landslide dynamics. The parameters measured and soil-water relationships were also compared to rainfall and slope movement at one of the landslides. The method used to acquire hydrologic data was cost-effective, and the field techniques may be useful for subsequent projects, such as slope-stability assessments and landslide-susceptibility modeling. Hydrologic parameters, volumetric water content, and water potential are pertinent to investigating the stability of landslides, which are often triggered or reactivated by rainfall. These methods can be used to support landslide-hazard assessment and improve our understanding of the long-term influence of moisture conditions in hillslope soils

    Dynamic Site Periods for the Jackson Purchase Region of Western Kentucky

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    Bridges, overpasses, and other engineered structures in the Jackson Purchase region of Western Kentucky are, of necessity, built on a thick column of loose to semi-consolidated sediments. Because these sediments tend to amplify seismically induced ground motions at preferred periods, structures with natural periods close to the preferred periods of amplification of the ground motions are particularly vulnerable to damages during an earthquake because of in-phase resonance. For this report, conventional seismic refraction and reflection techniques were used to determine the shearwave velocities of the more poorly consolidated, near-surface sediments for a matrix of sites in the region. Conventional seismic P-wave reflections along with existing drill hole and seismic reflection data in the region were then used to determine the depth to the top of the bedrock at the sites investigated. These data were used in SHAKE91 to calculate the fundamental period of the ground motion at the sites. This period, identified in the study as the dynamic site period, is the period at which ground motions in the sedimentary column are most apt to be amplified as a result of a seismic shear wave propagating from the top of the bedrock to the surface. Based on the results in this report, it is recommended that bridges, overpasses, and other engineered structures built in the region be designed so that their natural periods do not coincide with the fundamental period of the sedimentary column, thereby avoiding damage during an earthquake as a result of in-phase resonance

    Removal of the Northern Paleo-Teton Range along the Yellowstone Hotspot Track

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    Classically held mechanisms for removing mountain topography (e.g., erosion and gravitational collapse) require 10-100 Myr or more to completely remove tectonically generated relief. Here, we propose that mountain ranges can be completely and rapidly (\u3c 2 Myr) removed by a migrating hotspot. In western North America, multiple mountain ranges, including the Teton Range, terminate at the boundary with the relatively low relief track of the Yellowstone hotspot. This abrupt transition leads to a previously untested hypothesis that preexisting mountainous topography along the track has been erased. We integrate thermochronologic data collected from the footwall of the Teton fault with flexural-kinematic modeling and length-displacement scaling to show that the paleo-Teton fault and associated Teton Range was much longer (min. original length 190-210 km) than the present topographic expression of the range front (~65 km) and extended across the modern-day Yellowstone hotspot track. These analyses also indicate that the majority of fault displacement (min. 11.4-12.6 km) and the associated footwall mountain range growth had accumulated prior to Yellowstone encroachment at ~2 Ma, leading us to interpret that eastward migration of the Yellowstone hotspot relative to stable North America led to removal of the paleo-Teton mountain topography via posteruptive collapse of the range following multiple supercaldera (VEI 8) eruptions from 2.0 Ma to 600 ka and/or an isostatic collapse response, similar to ranges north of the Snake River plain. While this extremely rapid removal of mountain ranges and adjoining basins is probably relatively infrequent in the geologic record, it has important implications for continental physiography and topography over very short time spans

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43638/1/11186_2004_Article_BF00179274.pd

    Effect of Dam Emplacement and Water Level Changes on Sublacustrine Geomorphology and Recent Sedimentation in Jackson Lake, Grand Teton National Park (Wyoming, United States)

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    Dam installation on a deep hydrologically open lake provides the experimental framework necessary to study the influence of outlet engineering and changing base levels on limnogeological processes. Here, high-resolution seismic reflection profiles, sediment cores, and historical water level elevation datasets were employed to assess the recent depositional history of Jackson Lake, a dammed glacial lake located adjacent to the Teton fault in western Wyoming (USA). Prograding clinoforms imaged in the shallow stratigraphy indicate a recent lake-wide episode of delta abandonment. Submerged ∼11–12 m below the lake surface, these Gilbert-type paleo-deltas represent extensive submerged coarse-grained deposits along the axial and lateral margins of Jackson Lake that resulted from shoreline transgression following dam construction in the early 20th century. Other paleo-lake margin environments, including delta plain, shoreline, and glacial (drumlins, moraines) landforms were likewise inundated following dam installation, and now form prominent features on the lake floor. In deepwater, a detailed chronology was established using 137Cs, 210Pb, and reservoir-corrected 14C for a sediment core that spans ∼1654–2019 Common Era (CE). Dam emplacement (1908–1916 CE) correlates with a nearly five-fold acceleration in accumulation rates and a depositional shift towards carbonaceous sediments. Interbedded organic-rich black diatomaceous oozes and tan silts track changes in reservoir water level elevation, which oscillated in response to regional climate and downstream water needs between 1908 and 2019 CE. Chemostratigraphic patterns of carbon, phosphorus, and sulfur are consistent with a change in nutrient status and productivity, controlled initially by transgression-driven flooding of supralittoral soils and vegetation, and subsequently with water level changes. A thin gravity flow deposit punctuates the deepwater strata and provides a benchmark for turbidite characterization driven by hydroclimate change. Because the Teton fault is a major seismic hazard, end-member characterization of turbidites is a critical first step for accurate discrimination of mass transport deposits controlled by earthquakes in more ancient Jackson Lake strata. Results from this study illustrate the influence of dam installation on sublacustrine geomorphology and sedimentation, which has implications for lake management and ecosystem services. Further, this study demonstrates that Jackson Lake contains an expanded, untapped sedimentary archive recording environmental changes in the American West

    Protocol for a randomized controlled study of Iyengar yoga for youth with irritable bowel syndrome

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    <p>Abstract</p> <p>Introduction</p> <p>Irritable bowel syndrome affects as many as 14% of high school-aged students. Symptoms include discomfort in the abdomen, along with diarrhea and/or constipation and other gastroenterological symptoms that can significantly impact quality of life and daily functioning. Emotional stress appears to exacerbate irritable bowel syndrome symptoms suggesting that mind-body interventions reducing arousal may prove beneficial. For many sufferers, symptoms can be traced to childhood and adolescence, making the early manifestation of irritable bowel syndrome important to understand. The current study will focus on young people aged 14-26 years with irritable bowel syndrome. The study will test the potential benefits of Iyengar yoga on clinical symptoms, psychospiritual functioning and visceral sensitivity. Yoga is thought to bring physical, psychological and spiritual benefits to practitioners and has been associated with reduced stress and pain. Through its focus on restoration and use of props, Iyengar yoga is especially designed to decrease arousal and promote psychospiritual resources in physically compromised individuals. An extensive and standardized teacher-training program support Iyengar yoga's reliability and safety. It is hypothesized that yoga will be feasible with less than 20% attrition; and the yoga group will demonstrate significantly improved outcomes compared to controls, with physiological and psychospiritual mechanisms contributing to improvements.</p> <p>Methods/Design</p> <p>Sixty irritable bowel syndrome patients aged 14-26 will be randomly assigned to a standardized 6-week twice weekly Iyengar yoga group-based program or a wait-list usual care control group. The groups will be compared on the primary clinical outcomes of irritable bowel syndrome symptoms, quality of life and global improvement at post-treatment and 2-month follow-up. Secondary outcomes will include visceral pain sensitivity assessed with a standardized laboratory task (water load task), functional disability and psychospiritual variables including catastrophizing, self-efficacy, mood, acceptance and mindfulness. Mechanisms of action involved in the proposed beneficial effects of yoga upon clinical outcomes will be explored, and include the mediating effects of visceral sensitivity, increased psychospiritual resources, regulated autonomic nervous system responses and regulated hormonal stress response assessed via salivary cortisol.</p> <p>Trial registration</p> <p>ClinicalTrials.gov <a href="http://www.clinicaltrials.gov/ct2/show/NCT01107977">NCT01107977</a>.</p

    Impacting and Improving Communities: Identifying the best in the Parks and Recreation field

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    For both Roswell and Westerville a main focus has been on inclusion and diversity. Both are focusing on doing anything it might take to make sure everyone in their communities can participate and become successful. Cohorts that both Westerville and Roswell are adapting to fit the needs of are teens, senior adults, families, minorities, and persons with disabilities. They are creating both innovative programs along with experimental programs to see what will fit the needs of their communities the best, with great success they have become NRPA Gold Medal Finalists in 2013
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