Measurements of railgun generated supersonic plasma jet propagation and two jet oblique merging

Imploding spherical plasma liners have been proposed as a possible method for creating high-energy-density (HED) laboratory plasmas and as a standoff driver for magneto-inertial fusion (MIF). The Plasma Liner Experiment (PLX) planned a three-phase experimental program to study the feasibility of using railgun-driven supersonic jets to form imploding spherical plasma liners. The three phases are to investigate single-jet evolution during propagation, to merge 2--5 jets to assess the suitability of merging for liner formation, and to merge 30 jets in spherical symmetry to form a complete liner. We present here details of single-jet propagation and two-jet oblique merging experiments completed on PLX. A key component of this dissertation was the design, implementation, and operation of a novel 8 chord, fiber-coupled interferometer based on a long coherence length ($\u3e 100$~m) 561~nm diode-pumped solid state laser. This interferometer was a critical diagnostic in both single-jet propagation and two-jet merging studies. The long laser coherence length and fiber-optic design allowed signal and reference path lengths in the interferometer to be mismatched by many meters without signal degradation, greatly simplified interferometer optical layout, and added flexibility in interferometer positioning for both propagation and merging experiments. The interferometer sensitivity to ions, neutral atoms, and electrons required development of a phase shift analysis that incorporated the presence of neutrals, impurities, and multiply ionized species. Interferometry, coupled with spectroscopic ionization fraction estimates, was used to assess time resolved density profile measurements. Survey spectroscopy inferred both $T_e$ and ionization fraction $\mathit{f}$ via non-local-thermodynamic-equilibrium (non-LTE) atomic/equation-of-state (EOS) modeling. A fast CCD camera and photo-diode array allowed for assessment of plasma emission for velocity and jet profile measurements. Initial jet parameters were $n_e \sim 10^{16}$~cm$^{-3}$, $T_e \approx 1.4$~eV, velocity $v \approx 30$~km/s, sonic Mach number $M \approx 14$, diameter $\approx 5$~cm, and length $\approx 20$~cm. Interferometry in conjunction with CCD line-out data showed that the average jet density decreases by a factor of ten after propagating 40~cm, which is at the very low end of the 8--160 times drop predicted by ideal hydrodynamic theory. In oblique merge experiments, interferometry identified a density increase consistent with shock formation as opposed to simple plasma interpenetration, and the consistent formation of a density structure (with scale length ~ $\lambda_{ii^\prime}$) near the merge plane. Imaging showed formation of a multi-peaked emission structure transverse to the jet-merging plane with widths similar to the density structure. Since the merging regime was semi-collisional and the counter-streaming ion collisionality was comparable to the merged-structure size, we interpreted the observations using both hydrodynamic oblique shock and multi-fluid plasma theory and simulations. We find that our observations were consistent with oblique shock theory and a collisional, one-dimensional, multi-fluid plasma simulation

Anemia among women of reproductive age: An overview of global burden, trends, determinants, and drivers of progress in low- and middle-income countries

Relatively little progress has been made in reducing anemia prevalence among women of reproductive age (WRA anemia). Interventions, policies and programs aimed at reducing WRA anemia have the potential to improve overall not only women\u27s, but also children\u27s health and nutrition outcomes. To our knowledge, this is the first review that aimed to compile evidence on the determinants and drivers of WRA anemia reduction in low- and middle-income countries (LMICs). We synthesized the available evidence on the determinants and drivers, including government policies and programs, of WRA anemia and their mitigation strategies across a wide range of countries and geographies, thus contributing to the complex and multifactorial etiology of anemia. We carried out a systematic review of published peer-reviewed and grey literature assessing national or subnational decline in WRA anemia prevalence and the associated drivers in LMICs. Among the 21 studies meeting our inclusion criteria, proximal determinants of healthcare utilization, especially during pregnancy and with the use of contraceptives, were strong drivers of WRA anemia reduction. Changes in other maternal characteristics, such as an increase in age at first pregnancy, BMI, birth spacing, and reduction in parity, were associated with modest improvements in anemia prevalence. Access to fortified foods, especially iron-fortified flour, was also a predictor of a decrease in WRA anemia. Of the intermediate determinants, an increase in household wealth, educational attainment and access to improved sanitation contributed significantly to WRA anemia reduction. Although several common determinants emerged at the proximal and intermediate levels, the set of anemia determinants and the strength of the association between each driver and WRA anemia reduction were unique in each setting included in this review. Further research is needed to provide targeted recommendations for each country and region where WRA anemia prevalence remains high

Geophysical-geotechnical sensor networks for landslide monitoring

Landslides are often the result of complex, multi-phase processes where gradual deterioration of shear strength within the sub-surface precedes the appearance of surface features and slope failure. Moisture content increases and the build-up of associated pore water pressures are invariably associated with a loss of strength, and thus are a precursor to failure. Consequently, hydraulic processes typically play a major role in the development of landslides. Geoelectrical techniques, such as resistivity and self-potential are being increasingly applied to study landslide structure and the hydraulics of landslide processes. The great strengths of these techniques are that they provide spatial or volumetric information at the site scale, which, when calibrated with appropriate geotechnical and hydrogeological data, can be used to characterise lithological variability and monitor hydraulic changes in the subsurface. In this study we describe the development of an automated time-lapse electrical resistivity tomography (ALERT) and geotechnical monitoring system on an active inland landslide near Malton, North Yorkshire, UK. The overarching objective of the research is to develop a 4D landslide monitoring system that can characterise the subsurface structure of the landslide, and reveal the hydraulic precursors to movement. The site is a particularly import research facility as it is representative of many lowland UK situations in which weak mudrocks have failed on valley sides. Significant research efforts have already been expended at the site, and a number of baseline data sets have been collected, including ground and airborne LIDAR, geomorphologic and geological maps, and geophysical models. The monitoring network comprises an ALERT monitoring station connected to a 3D monitoring electrode array installed across an area of 5,500 m2, extending from above the back scarp to beyond the toe of the landslide. The ALERT instrument uses wireless telemetry (in this case GPRS) to communicate with an office based server, which runs control software and a database management system. The control software is used to schedule data acquisition, whilst the database management system stores, processes and inverts the remotely streamed ERT data. Once installed and configured, the system operates autonomously without manual intervention. Modifications to the ALERT system at this site have included the addition of environmental and geotechnical sensors to monitor rainfall, ground movement, ground and air temperature, and pore pressure changes within the landslide. The system is housed in a weatherproof enclosure and is powered by batteries charged by a wind turbine & solar panels. 3D ERT images generated from the landslide have been calibrated against resistivity information derived from laboratory testing of borehole core recovered from the landslide. The calibrated images revealed key aspects of the 3D landslide structure, including the lateral extent of slipped material and zones of depletion and accumulation; the surface of separation and the thickness of individual earth flow lobes; and the dipping in situ geological boundary between the bedrock formations. Time-lapse analysis of resistivity signatures has revealed artefacts within the images that are diagnostic of electrode movement. Analytical models have been developed to simulate the observed artefacts, from which predictions of electrode movement have been derived. This information has been used to correct the ERT data sets, and has provided a means of using ERT to monitor landslide movement across the entire ALERT imaging area. Initial assessment of seasonal changes in the resistivity signature has indicated that the system is sensitive to moisture content changes in the body of the landslide, thereby providing a basis for further development of the system with the aim of monitoring hydraulic precursors to failure

Pre-Operative Treatment For Disc Herniation: A Case Study Of Chronic Pain

Introduction: Chronic back pain is a prevalent condition that is a leading cause of disability and a major financial obligation for both patients and the healthcare system. Disc herniation contributes to the growing number of back pain cases and determining the best course of care can present a challenge. Surgical intervention carries risks including a complication termed Failed Back Syndrome. This case study provides further investigation into the impact of pain, a sensation that is debilitating and chronic for many. It will provide insight into both surgical and non-surgical interventions that will allow us to provide the highest quality of healthcare.Case Report: Ernie Merritt (E.M.), is a 50 year-old male who initially presented to his primary care provider after a work related injury leading to lumbar radiculopathy from disc herniation. After several failed attempts with pharmacologic and chiropractic treatment, he underwent a double laminectomy. Although his pain improved during the first post-op year, gradual degeneration of his intervertebral discs resulted in spinal fusion of the L4-S1 vertebrae three years after his initial procedure. The fusion was unsuccessful and resulted in severe, uncontrollable pain. E.M. underwent a third surgery, five years after his double laminectomy, to remove and replace the L4-S1 vertebrae with bone from his ilium. Fourteen years after his last operation E.M. still wears a brace to sit or stand. E.M.’s case was further complicated eleven years ago with a diagnosis of narcolepsy. Opiate medications were not tolerated for his chronic back pain due to increased fatigue. Daily use of methylphenidate 54 mg for narcolepsy has resulted in significant weight loss that has required additional funds on new back-braces. E.M. currently manages his pain with Advil 200mg twice a day and Tylenol 1,000mg daily though it is not effective. In addition to chronic pain and narcolepsy, he has been diagnosed with hypothyroidism, Raynaud’s, and arthritis. Additional surgeries include thyroidectomy with a ten-day hospital admission for pain control. E.M. lives in Southern Maine with his wife and dog. He has not been able to return to work since his initial injury, but serves as the facilitator for the Chronic Pain Support Group of Southern Maine. Since his first surgery E.M. tried to manage his pain through physical therapy, chiropractic care, and transcutaneous electrical nerve stimulation (TENS). He has found relief by remaining actively involved in his hobbies.Discussion: Failed Back Syndrome has a high incidence rate between 10% and 40 %. The incidence for failed lumbar fusion is higher between 30% and 46% with substantial costs for pre and post surgical care. Failed Back Syndrome in characterized by persistent back pain after one or more spinal surgeries. Patients suffering from chronic pain show a low recovery rate and often exhibit persistent and or relapsing pain due to inadequate treatment. Initial treatment typically focuses on sources of pain rather then addressing the problem from a patient centered approach. Osteopathic Manipulative Medicine encompasses strategies that decrease pain, enhance physiologic function, and shows promise as an alternative initial therapy for disc herniation and chronic lower back pain.https://dune.une.edu/com_studpost/1000/thumbnail.jp

Course-based Science Research Promotes Learning in Diverse Students at Diverse Institutions

Course-based research experiences (CREs) are powerful strategies for spreading learning and improving persistence for all students, both science majors and nonscience majors. Here we address the crucial components of CREs (context, discovery, ownership, iteration, communication, presentation) found across a broad range of such courses at a variety of academic institutions. We also address how the design of a CRE should vary according to the background of student participants; no single CRE format is perfect. We provide a framework for implementing CREs across multiple institutional types and several disciplines throughout the typical four years of undergraduate work, designed to a variety of student backgrounds. Our experiences implementing CREs also provide guidance on overcoming barriers to their implementation

A combined geomorphological and geophysical approach to characterising relict landslide hazard on the Jurassic Escarpments of Great Britain

The Jurassic Escarpment in the North York Moors in Northern Britain has a high density of deep-seated relict landslides but their regional hazard is poorly understood due to a lack of detailed case studies. Investigation of a typical relict landslide at Great Fryup Dale suggests that the crop of the Whitby Mudstone Formation is highly susceptible to landslide hazards. The mudstone lithologies along the Escarpment form large multiple rotational failures which break down at an accelerated rate during wetter climates and degrade into extensive frontal mudflows. Geomorphological mapping, high resolution LiDAR imagery, boreholes, and geophysical ERT surveys are deployed in a combined approach to delimit internal architecture of the landslide. Cross-sections developed from these data indicate that the main movement displaced a bedrock volume of c. 1 × 107 m3 with a maximum depth of rupture of c. 50 m. The mode of failure is strongly controlled by lithology, bedding, joint pattern, and rate of lateral unloading. Dating of buried peats using the AMS method suggests that the 10 m thick frontal mudflow complex was last active in the Late Holocene, after c. 2270 ± 30 calendar years BP. Geomorphic mapping and dating work indicates that the landslide is dormant, but slope stability modelling suggests that the slope is less stable than previously assumed; implying that this and other similar landslides in Britain may become more susceptible to reactivation or extension during future wetter climatic phases. This study shows the value of a multi-technique approach for landslide hazard assessment and to enhance national landslide inventories

Persistent net release of carbon dioxide and methane from an Alaskan lowland boreal peatland complex

Permafrost degradation in peatlands is altering vegetation and soil properties and impacting net carbon storage. We studied four adjacent sites in Alaska with varied permafrost regimes, including a black spruce forest on a peat plateau with permafrost, two collapse scar bogs of different ages formed following thermokarst, and a rich fen without permafrost. Measurements included year-round eddy covariance estimates of net carbon dioxide (CO2), mid-April to October methane (CH4) emissions, and environmental variables. From 2011 to 2022, annual rainfall was above the historical average, snow water equivalent increased, and snow-season duration shortened due to later snow return. Seasonally thawed active layer depths also increased. During this period, all ecosystems acted as slight annual sources of CO2 (13–59 g C m−2 year−1) and stronger sources of CH4 (11–14 g CH4 m−2 from ~April to October). The interannual variability of net ecosystem exchange was high, approximately ±100 g C m−2 year−1, or twice what has been previously reported across other boreal sites. Net CO2 release was positively related to increased summer rainfall and winter snow water equivalent and later snow return. Controls over CH4 emissions were related to increased soil moisture and inundation status. The dominant emitter of carbon was the rich fen, which, in addition to being a source of CO2, was also the largest CH4 emitter. These results suggest that the future carbon-source strength of boreal lowlands in Interior Alaska may be determined by the area occupied by minerotrophic fens, which are expected to become more abundant as permafrost thaw increases hydrologic connectivity. Since our measurements occur within close proximity of each other (≤1 km2), this study also has implications for the spatial scale and data used in benchmarking carbon cycle models and emphasizes the necessity of long-term measurements to identify carbon cycle process changes in a warming climate

Patterns of Ecosystem Structure and Wildfire Carbon Combustion Across Six Ecoregions of the North American Boreal Forest

Increases in fire frequency, extent, and severity are expected to strongly impact the structure and function of boreal forest ecosystems. An important function of the boreal forest is its ability to sequester and store carbon (C). Increasing disturbance from wildfires, emitting large amounts of C to the atmosphere, may create a positive feedback to climate warming. Variation in ecosystem structure and function throughout the boreal forest is important for predicting the effects of climate warming and changing fire regimes on C dynamics. In this study, we compiled data on soil characteristics, stand structure, pre-fire C pools, C loss from fire, and the potential drivers of these C metrics from 527 sites distributed across six ecoregions of North America’s western boreal forests. We assessed structural and functional differences between these fire-prone ecoregions using data from 417 recently burned sites (2004–2015) and estimated ecoregion-specific relationships between soil characteristics and depth from 167 of these sites plus an additional 110 sites (27 burned, 83 unburned). We found that northern boreal ecoregions were generally older, stored and emitted proportionally more belowground than aboveground C, and exhibited lower rates of C accumulation over time than southern ecoregions. We present ecoregion-specific estimates of depth-wise soil characteristics that are important for predicting C combustion from fire. As climate continues to warm and disturbance from wildfires increases, the C dynamics of these fire-prone ecoregions are likely to change with significant implications for the global C cycle and its feedbacks to climate change

Lowering water table reduces carbon sink strength and carbon stocks in northern peatlands

Peatlands at high latitudes have accumulated \u3e400 Pg carbon (C) because saturated soil and cold temperatures suppress C decomposition. This substantial amount of C in Arctic and Boreal peatlands is potentially subject to increased decomposition if the water table (WT) decreases due to climate change, including permafrost thaw-related drying. Here, we optimize a version of the Organizing Carbon and Hydrology In Dynamic Ecosystems model (ORCHIDEE-PCH4) using site-specific observations to investigate changes in CO and CH fluxes as well as C stock responses to an experimentally manipulated decrease of WT at six northern peatlands. The unmanipulated control peatlands, with the WT (seasonal max up to 45 cm) below the surface, currently act as C sinks in most years (58 ± 34 g C m year ; including 6 ± 7 g C-CH m year emission). We found, however, that lowering the WT by 10 cm reduced the CO sink by 13 ± 15 g C m year and decreased CH emission by 4 ± 4 g CH m year , thus accumulating less C over 100 years (0.2 ± 0.2 kg C m ). Yet, the reduced emission of CH , which has a larger greenhouse warming potential, resulted in a net decrease in greenhouse gas balance by 310 ± 360 g CO m year . Peatlands with the initial WT close to the soil surface were more vulnerable to C loss: Non-permafrost peatlands lost \u3e2 kg C m over 100 years when WT is lowered by 50 cm, while permafrost peatlands temporally switched from C sinks to sources. These results highlight that reductions in C storage capacity in response to drying of northern peatlands are offset in part by reduced CH emissions, thus slightly reducing the positive carbon climate feedbacks of peatlands under a warmer and drier future climate scenario