343 research outputs found

    A Correlation and Stratigraphy of Detailed Measured Core Sections of the Waynesville and Liberty Formations (Katian; Richmondian) - Transecting Warren, Clinton, and Fayette Counties of Ohio

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    The stratigraphy of the Cincinnatian is difficult to understand and interpret which has resulted in various models for deposition ranging from a layer cake model with continuous beds to completely discontinuous beds. The interest of this study is the Liberty and Waynesville Formations (previously part of the Bull Fork Formation); these are Late Ordovician (Katian; Richmondian) units of predominantly limestone and shale. This project assesses the continuity of fine scale beds within these formations across a small area (approx. the size of Ohio’s Clinton County) by correlating measured sections from drill cores. The project involved the study of five rock cores (cores 2627, 3240, 868, 2682, and 2620) held in the ODNR H.R. Collins Core Repository and the comparison with published sections and unpublished field notes from neighboring outcrops. The project’s goal was to increase the detail of the measured sections to a one-inch resolution for the Waynesville and Liberty Formations and to increase the number of completed sections for the northeastern portion of the Cincinnati Arch. The paleontology was noted, when visible in core section, for correlation with the known faunal epiboles. The use of these has proven troublesome when examining cores due to the inherent limitations in encountering the fossils when drilling which has led to more reliance on lithological correlations between the cores. This project has revealed continuity of sets of lithological beds; however, no continuous individual lithological beds were recognizable in core samples across the region. Without the use of fossil correlation, there are no continuous lithological beds and no clear formational contacts for the Liberty, Waynesville, and Whitewater Formations. Without the use of these fossil epiboles, the differentiation of the formations is extremely difficult and nearly impossible in some localities. In summary, in areas where surface outcrops are limited for these formations, core sections can be used to correlate the larger cycles, but the fine resolution correlation requires the identification of epiboles, which is only practical in outcrop

    Three-dimensional finite-element elastic analysis of a thermally cycled single-edge wedge geometry specimen

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    An elastic stress analysis was performed on a wedge specimen (prismatic bar with single-wedge cross section) subjected to thermal cycles in fluidized beds. Seven different combinations consisting of three alloys (NASA TAZ-8A, 316 stainless steel, and A-286) and four thermal cycling conditions were analyzed. The analyses were performed as a joint effort of two laboratories using different models and computer programs (NASTRAN and ISO3DQ). Stress, strain, and temperature results are presented

    Microstructures Produced by Hadrosaur Bones from Alaska and Wyoming

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    Since 2005 when Dr. Mary Schweitzer made the first discovery, microstructures with the appearance of “osteocytes” and “blood vessels” have been recovered from fossils of various localities, dating back as far as the Triassic. The majority of these finds have come from dense, cortical bone but recently have been discovered in cancellous bone. Since her initial discovery, Schweitzer has done a lot of work to verify that these microstructures are not biofilms, but instead are original organic tissue. This project was looking to get similar results to Schweitzer’s research and to find a simple test method for the initial discovery of soft tissue using easily available supplies. Fragments of “float” Edmontosaurus bones were collected from Eastern Wyoming and “in-situ” hadrosaur bones collected from Alaska. Two different techniques were used, the first method implemented daily changes of a 0.5 M solution of EDTA and the second was a solution of 2M HCl; both are known techniques for demineralizing modern bone. Using the solution of HCl, the bones were subjected to daily solution changes until completely demineralized. The sediment left over was then used to make covered slides, which were then analyzed and photographed with a petrographic scope. This analysis revealed certain microstructures of several types that had been freed from the bone. Comparing the microstructures with previous work done by other researchers indicates that these structures have the morphological appearance of original soft tissue blood vessels and osteocytes. In every HCl sample, the material from Wyoming produced highly fragmented sections of these “blood vessels”, while the Alaska material produced larger, abundant “blood vessels” and in addition, rarer “osteocytes”. These samples were of cancellous bone and ossified tendon. The EDTA samples have yet to produce any original organic structures. Further stain tests will be performed for verification of the organic nature of the structures. The ease in finding these microstructures using basic supplies and in weathered bones seems to indicate the possibility of original organic preservation in fossil bones may be quite prevalent, possibly even the norm

    Severe pediatric neurological manifestations with SARS-CoV-2 or MIS-C hospitalization and new morbidity

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    IMPORTANCE: Neurological manifestations during acute SARS-CoV-2-related multisystem inflammatory syndrome in children (MIS-C) are common in hospitalized patients younger than 18 years and may increase risk of new neurocognitive or functional morbidity. OBJECTIVE: To assess the association of severe neurological manifestations during a SARS-CoV-2-related hospital admission with new neurocognitive or functional morbidities at discharge. DESIGN, SETTING, AND PARTICIPANTS: This prospective cohort study from 46 centers in 10 countries included patients younger than 18 years who were hospitalized for acute SARS-CoV-2 or MIS-C between January 2, 2020, and July 31, 2021. EXPOSURE: Severe neurological manifestations, which included acute encephalopathy, seizures or status epilepticus, meningitis or encephalitis, sympathetic storming or dysautonomia, cardiac arrest, coma, delirium, and stroke. MAIN OUTCOMES AND MEASURES: The primary outcome was new neurocognitive (based on the Pediatric Cerebral Performance Category scale) and/or functional (based on the Functional Status Scale) morbidity at hospital discharge. Multivariable logistic regression analyses were performed to examine the association of severe neurological manifestations with new morbidity in each SARS-CoV-2-related condition. RESULTS: Overall, 3568 patients younger than 18 years (median age, 8 years [IQR, 1-14 years]; 54.3% male) were included in this study. Most (2980 [83.5%]) had acute SARS-CoV-2; the remainder (588 [16.5%]) had MIS-C. Among the patients with acute SARS-CoV-2, 536 (18.0%) had a severe neurological manifestation during hospitalization, as did 146 patients with MIS-C (24.8%). Among survivors with acute SARS-CoV-2, those with severe neurological manifestations were more likely to have new neurocognitive or functional morbidity at hospital discharge compared with those without severe neurological manifestations (27.7% [n = 142] vs 14.6% [n = 356]; P \u3c .001). For survivors with MIS-C, 28.0% (n = 39) with severe neurological manifestations had new neurocognitive and/or functional morbidity at hospital discharge compared with 15.5% (n = 68) of those without severe neurological manifestations (P = .002). When adjusting for risk factors in those with severe neurological manifestations, both patients with acute SARS-CoV-2 (odds ratio, 1.85 [95% CI, 1.27-2.70]; P = .001) and those with MIS-C (odds ratio, 2.18 [95% CI, 1.22-3.89]; P = .009) had higher odds of having new neurocognitive and/or functional morbidity at hospital discharge. CONCLUSIONS AND RELEVANCE: The results of this study suggest that children and adolescents with acute SARS-CoV-2 or MIS-C and severe neurological manifestations may be at high risk for long-term impairment and may benefit from screening and early intervention to assist recovery

    A virtual community of practice: An international educational series in pediatric neurocritical care

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    Pediatric neurocritical care (PNCC) is a rapidly growing field. Challenges posed by the COVID-19 pandemic on trainee exposure to educational opportunities involving direct patient care led to the creative solutions for virtual education supported by guiding organizations such as the Pediatric Neurocritical Care Research Group (PNCRG). Our objective is to describe the creation of an international, peer-reviewed, online PNCC educational series targeting medical trainees and faculty. More than 1600 members of departments such as pediatrics, pediatric critical care, and child neurology hailing from 75 countries across six continents have participated in this series over a 10-month period. We created an online educational channel in PNCC with over 2500 views to date and over 130 followers. This framework could serve as a roadmap for other institutions and specialties seeking to address the ongoing problems of textbook obsolescence relating to the rapid acceleration in knowledge acquisition, as well as those seeking to create new educational content that offers opportunities for an interactive, global audience. Through the creation of a virtual community of practice, we have created an international forum for pediatric healthcare providers to share and learn specialized expertise and best practices to advance global pediatric health

    Reduction in overt and silent stroke recurrence rate following cerebral revascularization surgery in children with sickle cell disease and severe cerebral vasculopathy

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    Background Children with sickle cell disease (SCD) and moyamoya may benefit from indirect cerebral revascularization surgery in addition to chronic blood transfusion therapy for infarct prevention. We sought to compare overt and silent infarct recurrence rates in children with SCD undergoing revascularization. Methods This was a retrospective cohort study of all children with SCD and moyamoya treated at two children’s hospitals. Clinical events and imaging studies were reviewed. Results Twenty-seven children with SCD and confirmed moyamoya receiving chronic transfusion therapy were identified, of whom 12 underwent indirect cerebral revascularization. Two subjects had post-operative transient ischemic attacks and another had a subarachnoid blood collection, none of which caused permanent consequences. Two subjects had surgical wound infections. Among these 12 children, the rate of overt and silent infarct recurrence decreased from 13.4 infarcts/100 patient-years before revascularization to 0 infarcts/100 patient-years after revascularization (p=0.0057); the post-revascularization infarct recurrence rate was also significantly lower than the overall infarct recurrence of 8.87 infarcts/100 patient-years in 15 children without cerebral revascularization (p=0.025). Conclusion The rate of overt and silent infarct recurrence was significantly lower following indirect cerebral revascularization. A prospective study of cerebral revascularization in children with SCD is needed

    Cognitive dysfunction after analgesia and sedation: Out of the operating room and into the pediatric intensive care unit

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    In the midst of concerns for potential neurodevelopmental effects after surgical anesthesia, there is a growing awareness that children who require sedation during critical illness are susceptible to neurologic dysfunctions collectively termed pediatric post-intensive care syndrome, or PICS-p. In contrast to healthy children undergoing elective surgery, critically ill children are subject to inordinate neurologic stress or injury and need to be considered separately. Despite recognition of PICS-p, inconsistency in techniques and timing of post-discharge assessments continues to be a significant barrier to understanding the specific role of sedation in later cognitive dysfunction. Nonetheless, available pediatric studies that account for analgesia and sedation consistently identify sedative and opioid analgesic exposures as risk factors for both in-hospital delirium and post-discharge neurologic sequelae. Clinical observations are supported by animal models showing neuroinflammation, increased neuronal death, dysmyelination, and altered synaptic plasticity and neurotransmission. Additionally, intensive care sedation also contributes to sleep disruption, an important and overlooked variable during acute illness and post-discharge recovery. Because analgesia and sedation are potentially modifiable, understanding the underlying mechanisms could transform sedation strategies to improve outcomes. To move the needle on this, prospective clinical studies would benefit from cohesion with regard to datasets and core outcome assessments, including sleep quality. Analyses should also account for the wide range of diagnoses, heterogeneity of this population, and the dynamic nature of neurodevelopment in age cohorts. Much of the related preclinical evidence has been studied in comparatively brief anesthetic exposures in healthy animals during infancy and is not generalizable to critically ill children. Thus, complementary animal models that more accurately reverse translate critical illness paradigms and the effect of analgesia and sedation on neuropathology and functional outcomes are needed. This review explores the interactive role of sedatives and the neurologic vulnerability of critically ill children as it pertains to survivorship and functional outcomes, which is the next frontier in pediatric intensive care

    A major genetic locus in <i>Trypanosoma brucei</i> is a determinant of host pathology

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    The progression and variation of pathology during infections can be due to components from both host or pathogen, and/or the interaction between them. The influence of host genetic variation on disease pathology during infections with trypanosomes has been well studied in recent years, but the role of parasite genetic variation has not been extensively studied. We have shown that there is parasite strain-specific variation in the level of splenomegaly and hepatomegaly in infected mice and used a forward genetic approach to identify the parasite loci that determine this variation. This approach allowed us to dissect and identify the parasite loci that determine the complex phenotypes induced by infection. Using the available trypanosome genetic map, a major quantitative trait locus (QTL) was identified on T. brucei chromosome 3 (LOD = 7.2) that accounted for approximately two thirds of the variance observed in each of two correlated phenotypes, splenomegaly and hepatomegaly, in the infected mice (named &lt;i&gt;TbOrg1&lt;/i&gt;). In addition, a second locus was identified that contributed to splenomegaly, hepatomegaly and reticulocytosis (&lt;i&gt;TbOrg2&lt;/i&gt;). This is the first use of quantitative trait locus mapping in a diploid protozoan and shows that there are trypanosome genes that directly contribute to the progression of pathology during infections and, therefore, that parasite genetic variation can be a critical factor in disease outcome. The identification of parasite loci is a first step towards identifying the genes that are responsible for these important traits and shows the power of genetic analysis as a tool for dissecting complex quantitative phenotypic traits

    Development of an Integrated Countermeasure Device for Long Duration Space Flight and Exploration Missions

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    Musculoskeletal, cardiovascular, and sensorimotor deconditioning have been observed consistently in astronauts and cosmonauts following long-duration spaceflight. Studies in bed rest, a spaceflight analog, have shown that high intensity resistive or aerobic exercise attenuates or prevents musculoskeletal and cardiovascular deconditioning, respectively, but complete protection has not been achieved during spaceflight. Exercise countermeasure hardware used during earlier International Space Station (ISS) missions included a cycle ergometer, a treadmill, and the interim resistive exercise device (iRED). Effectiveness of the countermeasures may have been diminished by limited loading characteristics of the iRED as well as speed restrictions and subject harness discomfort during treadmill exercise. The Advanced Resistive Exercise Device (ARED) and the second generation treadmill were designed to address many of the limitations of their predecessors, and anecdotal reports from ISS crews suggest that their conditioning is better preserved since the new hardware was delivered in 2009. However, several countermeasure devices to protect different physiologic systems will not be practical during exploration missions when the available volume and mass will be severely restricted. The combined countermeasure device (CCD) integrates a suite of hardware into one device intended to prevent spaceflight-induced musculoskeletal, cardiovascular, and sensorimotor deconditioning. The CCD includes pneumatic loading devices with attached cables for resistive exercise, a cycle for aerobic exercise, and a 6 degree of freedom motion platform for balance training. In a proof of concept test, ambulatory untrained subjects increased muscle strength (58%) as well as aerobic capacity (26%) after 12-weeks of exercise training with the CCD (without balance training), improvements comparable to those observed with traditional exercise training. These preliminary results suggest that this CCD can concurrently improve musculoskeletal and cardiovascular conditioning in ambulatory subjects, but further work is required to validate its use as countermeasure to spaceflight-induced deconditioning
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