Lithostratigraphy and depositional environments of the Pitkin Limestone (Chesterian, Mississippian) in portions of Cherokee, Muskogee, and Sequoyah Counties, Oklahoma

Thesis (M.S.)--University of Oklahoma, 1981.This thesis provides a detailed lithostratigraphic analysis and interpretation of depositional environments of the pitkin limestone (Chesterian, Mississippian) in a portion of northeastern Oklahoma. The study area is located mostly in Cherokee County but also includes portions of Muskogee and Sequoyah Counties. Twenty-eight stratigraphic sections were measured and studied. The Fayetteville Shale, which immediately underlies the Pitkin, was found to have a highly variable thickness in northeast Oklahoma. An adequate explanation of this feature is not possible at this time. The two fonnations are thought to have been at least in part deposited contemporaneously. Together they form a shoaling upward sequence. Eleven facies were delineated in the study area: (1) Oolite Facies, (2) Oolitic Facies, (3) Bioclastic Facies, (4) Encrinite Facies, (5) Oncolitic Facies, (6) Nodular Limestone and Shale Facies, (7) Wackestone Facies , (8) Peloidal Facies, (9) Mudstone Facies, (10) Shale Facies, and (11) Mound Facies. Most of the Pitkin lithofacies were deposited in high energy shallow marine environments. The distribution of these facies and their inferred depositional environments suggest that the Pitkin was a platform carbonate. An unconformity of regional extent separates Mississippian and Pennsylvanian strata on the Ozark Uplift and is easily recognized in the field because of the contrast between the light gray-weathering limestones of the Pitkin and the brown weathering sandy grainstones of the overlying Sausbee Formation (Lower Pennsylvanian). The Sausbee locally has at its base a cobble conglomerate of Pitkin Limestone clasts. A pre-Pennsylvanian north-south trending fluvial valley feature, with a regional relief of at least 60 feet, can be delineated in Cherokee and northern Sequoyah Counties by cross sections and isopach maps of the Pitkin. The Pitkin is locally removed within the study area with the Sausbee resting directly on the Fayetteville Shale. The conformable Chesterian stratigraphic sequence of Hindsville-Fayetteville-Pitkin in the Oklahoma Ozark Region may represent a carbonate shelf cycle or mesothem. The Hindsville is interpreted as a transgressive unit, the Fayetteville as being both transgressive and regressive, and the Pitkin as a regressive carbonate unit. Depositional strike of the Pitkin Limestone shifts from northwest-southeast in Muskogee and Wagoner Counties, Oklahoma to northeast-southwest in Washington and Crawford Counties, Arkansas as a result of a positive topographic expression of the Ozark Uplift in Oklahoma

Combining Differential Kinematics and Optical Flow for Automatic Labeling of Continuum Robots in Minimally Invasive Surgery

International audienceThe segmentation of continuum robots in medical images can be of interest for analyzing surgical procedures or for controlling them. However, the automatic segmentation of continuous and flexible shapes is not an easy task. On one hand conventional approaches are not adapted to the specificities of these instruments, such as imprecise kinematic models, and on the other hand techniques based on deep-learning showed interesting capabilities but need many manually labeled images. In this article we propose a novel approach for segmenting continuum robots on endoscopic images, which requires no prior on the instrument visual appearance and no manual annotation of images. The method relies on the use of the combination of kinematic models and differential kinematic models of the robot and the analysis of optical flow in the images. A cost function aggregating information from the acquired image, from optical flow and from robot encoders is optimized using particle swarm optimization and provides estimated parameters of the pose of the continuum instrument and a mask defining the instrument in the image. In addition a temporal consistency is assessed in order to improve stochastic optimization and reject outliers. The proposed approach has been tested for the robotic instruments of a flexible endoscopy platform both for benchtop acquisitions and an in vivo video. The results show the ability of the technique to correctly segment the instruments without a prior, and in challenging conditions. The obtained segmentation can be used for several applications, for instance for providing automatic labels for machine learning techniques

Anaerobic Biodegradation Tests of Poly(lactic acid) under Mesophilic and Thermophilic Conditions Using a New Evaluation System for Methane Fermentation in Anaerobic Sludge

Anaerobic biodegradation tests of poly(lactic acid) (PLA) powder were done at the thermophilic (55 °C) and mesophilic temperature (35 °C) under aquatic conditions [total solid concentrations of the used sludge were 2.07% (at 55 °C) and 2.24% (at 35 °C)] using a newly developed evaluation system. With this system, the evolved biogas is collected in a gas sampling bag at atmospheric pressure. This method is more convenient than using a pressure transducer or inverted graduated cylinder submerged in water. PLA was degraded about 60% in 30 days, about 80% in 40 days and about 90% in 60 days at 55 °C. On the other hand, the PLA degradation started in 55 days at 35 °C and degradation rate was much slower than at 55 °C

Spatial and temporal variations in Pb concentrations and isotopic composition in road dust, farmland soil and vegetation in proximity to roads since cessation of use of leaded petrol in the UK

Results are presented for a study of spatial distributions and temporal trends in concentrations of lead (Pb) from different sources in soil and vegetation of an arable farm in central Scotland in the decade since the use of leaded petrol was terminated. Isotopic analyses revealed that in all of the samples analysed, the Pb conformed to a binary mixture of petrol Pb and Pb from industrial or indigenous geological sources and that locally enhanced levels of petrol Pb were restricted to within 10 m of a motorway and 3 m of a minor road. Overall, the dominant source of Pb was historical emissions from nearby industrial areas. There was no discernible change in concentration or isotopic composition of Pb in surface soil or vegetation over the decade since the ban on the sale of leaded petrol. There was an order of magnitude decrease in Pb concentrations in road dust over the study period, but petrol Pb persisted at up to 43% of the total Pb concentration in 2010. Similar concentrations and spatial distributions of petrol Pb and non petrol Pb in vegetation in both 2001 and 2010, with enhanced concentrations near roads, suggested that redistribution of previously deposited material has operated continuously over that period, maintaining a transfer pathway of Pb into the biosphere. The results for vegetation and soil transects near minor roads provided evidence of a non petrol Pb source associated with roads/traffic, but surface soil samples from the vicinity of a motorway failed to show evidence of such a source

Distortion and instability compensation with deep learning for rotational scanning endoscopic optical coherence tomography

Optical Coherence Tomography (OCT) is increasingly used in endoluminal procedures since it provides high-speed and high resolution imaging. Distortion and instability of images obtained with a proximal scanning endoscopic OCT system are significant due to the motor rotation irregularity, the friction between the rotating probe and outer sheath and synchronization issues. On-line compensation of artefacts is essential to ensure image quality suitable for real-time assistance during diagnosis or minimally invasive treatment. In this paper, we propose a new online correction method to tackle both B-scan distortion, video stream shaking and drift problem of endoscopic OCT linked to A-line level image shifting. The proposed computational approach for OCT scanning video correction integrates a Convolutional Neural Network (CNN) to improve the estimation of azimuthal shifting of each A-line. To suppress the accumulative error of integral estimation we also introduce another CNN branch to estimate a dynamic overall orientation angle. We train the network with semi-synthetic OCT videos by intentionally adding rotational distortion into real OCT scanning images. The results show that networks trained on this semi-synthetic data generalize to stabilize real OCT videos, and the algorithm efficacy is demonstrated on both ex vivo and in vivo data, where strong scanning artifacts are successfully corrected. (c) 2022 The Authors. Published by Elsevier B.V

A Novel Telemanipulated Robotic Assistant for Surgical Endoscopy: Preclinical Application to ESD

International audienceObjective: Minimally invasive surgical interventions in the gastrointestinal tract, such as Endoscopic Submucosal Dissection (ESD), are very difficult for surgeons when performed with standard flexible endoscopes. Robotic flexible systems have been identified as a solution to improve manipulation. However, only a few such systems have been brought to preclinical trials as of now. As a result, novel robotic tools are required.Methods: We developed a telemanipulated robotic device, called STRAS, which aims to assist surgeons during intraluminal surgical endoscopy. This is a modular system, based on a flexible endoscope and flexible instruments, which provides 10 degrees of freedom (DoFs). The modularity allows to easily set up the robot and to navigate towards the operating area. The robot can then be teleoperated using master interfaces specifically designed to intuitively control all available DoFs. STRAS capabilities have been tested in laboratory conditions and during preclinical experiments. Results: We report twelve colorectal ESDs performed in pigs, in which large lesions were successfully removed. Dissection speeds are compared with those obtained in similar conditions with the manual Anubiscope TM platform from Karl Storz. We show significant improvements (p = 0.01).Conclusion: These experiments show that STRAS (v2) provides sufficient DoFs, workspace and force to perform ESD, that it allows a single surgeon to perform all the surgical tasks and that performances are improved with respect to manual systems. Significance: The concepts developed for STRAS are validated and could bring new tools for surgeons to improve comfort, ease and performances for intraluminal surgical endoscopy

Neuroglia at the crossroads of homoeostasis, metabolism and signalling: evolution of the concept

Ever since Rudolf Virchow in 1858 publicly announced his apprehension of neuroglia being a true connective substance, this concept has been evolving to encompass a heterogeneous population of cells with various forms and functions. We briefly compare the 19th–20th century perspectives on neuroglia with the up-to-date view of these cells as an integral, and possibly integrating, component of brain metabolism and signalling in heath and disease. We conclude that the unifying property of otherwise diverse functions of various neuroglial cell sub-types is to maintain brain homoeostasis at different levels, from whole organ to molecular