96 results on '"Keith Nelson"'
Search Results
2. Extraintestinal Pathogenic Escherichia Coli Causes Necrohemorrhagic Pneumonia in Multiple Research Dogs
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Sarah E. Coe, Michelle A. Magagna, Annie Zimmerman, April George, Caitlyn Carter, Charissa Dean, and Keith Nelson
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Cell Biology ,Toxicology ,Molecular Biology ,Pathology and Forensic Medicine - Abstract
Extraintestinal pathogenic Escherichia coli expressing cytotoxic necrotizing factor (CNF) 1 and 2 virulence factors is a rarely reported cause of acute, fatal necrohemorrhagic pneumonia in canines. A review of cases of necrohemorrhagic pneumonia in beagles at our facility between 2013 and 2021 revealed 21 dogs that died or were euthanized after acute onset lethargy, dyspnea, and hemorrhage. Some affected animals had recently been transported to the facility. In all dogs, lung lobes were discolored dark red and consolidated. Histologic lesions in 17 of these included alveolar necrosis, hemorrhage, edema, fibrin, acute inflammation, and intralesional colonies of bacilli. Lung was cultured for 10 dogs with E. coli isolated and CNF1 identified by virulence factor PCR in 7 of those. Based on these findings, extraintestinal E. coli should be considered an important cause of acute fatal necrohemorrhagic pneumonia in purpose-bred beagle research dogs and may be associated with a recent history of transport.
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- 2022
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3. Time-resolved measurement of stress wave profile during femtosecond laser processing of synthetic silica glass
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Junya Hattori, Yusuke Ito, David Veysset, Keiichi Nakagawa, Keith Nelson, and Naohiko Sugita
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- 2023
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4. Vaccines
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Rani S. Sellers and Keith Nelson
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- 2023
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5. Contributors
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Basel T. Assaf, Adam D. Aulbach, Virunya Bhat, Brad Bolon, William M. Bracken, Alys E. Bradley, Glenn H. Cantor, Kevin B. Donnelly, Elodie Drevon-Gaillot, Stephen K. Durham, Jeffery A. Engelhardt, Daniela Ennulat, James Fikes, John Reginald Foster, Kathleen Funk, Sibylle Gröters, Magali R. Guffroy, Silvia Guionaud, Katherine Hammerman, Carole Harbison, Claudia Harper, Christopher Hurst, Evan B. Janovitz, Kevin Keane, Stephanie Klein, Rebecca Kohnken, Michael W. Leach, Xiantang Li, René Meisner, Keith Nelson, Thomas Nolte, Arun R. Pandiri, Jonathan A. Phillips, Colin G. Rousseaux, Daniel G. Rudmann, Keegan C. Rudmann, Aaron M. Sargeant, JoAnn C.L. Schuh, A. Eric Schultze, Rani S. Sellers, James A. Swenberg, Eric Tien, John L. Vahle, Lyn M. Wancket, and Charles E. Wood
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- 2023
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6. Extraintestinal Pathogenic
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Sarah E, Coe, Michelle A, Magagna, Annie, Zimmerman, April, George, Caitlyn, Carter, Charissa, Dean, and Keith, Nelson
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Dogs ,Extraintestinal Pathogenic Escherichia coli ,Escherichia coli ,Animals ,Hemorrhage ,Pneumonia ,Escherichia coli Infections - Abstract
Extraintestinal pathogenic
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- 2022
7. Low-Slope Roofing Installations and Third-Party Observations: A Critical Review of Noncompliance Management
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Benjamin Meyer, Keith Nelson, and Kristin Westover
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- 2022
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8. Cardiac Rhabdomyoma in Four Göttingen Minipigs
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Laine E. Feller, Aaron Sargeant, E. J. Ehrhart, Bethany Balmer, Keith Nelson, and Jennifer Lamoureux
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Cell Biology ,Toxicology ,Molecular Biology ,Pathology and Forensic Medicine - Abstract
Göttingen minipigs are increasingly used as an alternative large animal model in nonclinical toxicology studies, and proliferative lesions in this species are rare. Here, we report four cases of cardiac rhabdomyoma in Göttingen minipigs, an incidental and benign mass in the heart. Three cases lacked gross observations and had a microscopic nodule in either the left ventricle or interventricular septum. The last case had a large, firm, raised nodule on a left ventricular papillary muscle noted at necropsy, with additional microscopic intramural masses in the left ventricular wall. In all cases, microscopic evaluation revealed well-circumscribed, expansile nodules composed of bundles of large, highly vacuolated, ovoid to polygonal cells with variable cytoplasmic processes radiating from a centrally located nucleus. Cells displayed patchy accumulation of intracytoplasmic, PAS-positive material and haphazardly arranged cytoplasmic cross-striations. There was no evidence of cardiac insufficiency or other data to suggest the masses were clinically meaningful. Cardiac rhabdomyomas have been reported in meat-hybrid swine, with a breed predisposition in red wattle. This lesion is well established in guinea pigs, but documentation in other laboratory species used in toxicologic studies is limited to two beagle dogs. To our knowledge, this is the first report of spontaneous cardiac rhabdomyoma in Göttingen minipigs.
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- 2023
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9. Contributors
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Rick Adler, Famke Aeffner, Laura E. Armstrong, Dmitri Artemov, Adam D. Aulbach, Bindu M. Bennet, Eric A. Blomme, Brad Bolon, Christopher J. Bowman, Molly Boyle, Alys Bradley, Dino Bradley, Danielle Brown, Pierre R. Bushel, Ellen Cannady, Mark F. Cesta, Curtis Chan, Jennifer A. Chilton, Peter J.M. Clements, Torrie A. Crabbs, Myrtle A. Davis, Sandy Eldridge, Daniela Ennulat, Jeffrey Everitt, Isabel Figueroa, James D. Fikes, Thomas Forest, Catherine A. Foss, John R. Foster, Kathleen Gabrielson, Shayne C. Gad, Kapil Gadkar, Jinping Gan, David Garcia-Tapia, Frank J. Geoly, Wendy G. Halpern, Jerry F. Hardisty, Wanda M. Haschek, Kathleen Marie Heinz-Taheny, Kristi Helke, Lauren E. Himmel, Mark J. Hoenerhoff, Jennifer L. Ingram–Ross, Armando R. Irizarry Rovira, Evan B. Janovitz, Kishore Katyayan, Charlotte M. Keenan, Angela King-Herbert, Steven T. Laing, Lois D. Lehman-McKeeman, Na Li, Calvert Louden, Claire Lyons, Kevin McDorman, Elizabeth McInnes, Lyn Miller Wancket, Sheroy Minocherhomji, Sébastien Monette, James Morrison, Vasanthi Mowat, Sydney Mukaratirwa, Keith Nelson, Arun R. Pandiri, Tracey Papenfuss, Nita Patel, Daniel J. Patrick, Shari A. Price, Deepa B. Rao, James T. Raymond, Jennifer Rojko, Colin G. Rousseaux, Sara F. Santagostino, Aaron Sargeant, Christina Satterwhite, A. Eric Schultze, Vanessa Schumacher, Cheryl Scudamore, Keith R. Shockley, Bhanu P. Singh, David M. Stresser, Polina Sysa-Shah, Debra A. Tokarz, Terry Van Vleet, Matthew A. Wallig, Jin Wang, Cynthia J. Willson, Kristin Lewis Wilson, Christopher T. Winkelmann, Jeffrey C. Wolf, Charles Wood, Daniela Bumbaca Yadav, and Mark Zarella
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- 2022
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10. Basic Approaches in Anatomic Toxicologic Pathology
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Torrie A. Crabbs and Keith Nelson
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- 2022
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11. Scientific and Regulatory Policy Committee Points to Consider*: Approaches to the Conduct and Interpretation of Vaccine Safety Studies for Clinical and Anatomic Pathologists
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Ronnie Chamanza, Niraj Tripathi, Bindu Bennet, Marie-France Perron Lepage, Jayanthi J. Wolf, Karissa Adkins, Keith Nelson, Sean P. Troth, Sebastien Laurent, and Rani S. Sellers
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Vaccine safety ,040301 veterinary sciences ,Drug Evaluation, Preclinical ,Toxicology ,Pathology and Forensic Medicine ,0403 veterinary science ,03 medical and health sciences ,Toxicity Tests ,Injection site ,Animals ,Humans ,Molecular Biology ,030304 developmental biology ,Clinical Trials as Topic ,Vaccines ,0303 health sciences ,Pathology, Clinical ,Species selection ,Interpretation (philosophy) ,Data interpretation ,04 agricultural and veterinary sciences ,Cell Biology ,Regulatory policy ,Pathologists ,Clinical trial ,Disease Models, Animal ,Policy ,Regulatory toxicology ,Research Design ,Engineering ethics ,Psychology - Abstract
The design and execution of toxicology studies supporting vaccine development have some unique considerations relative to those supporting traditional small molecules and biologics. A working group of the Society of Toxicologic Pathology Scientific and Regulatory Policy Committee conducted a review of the scientific, technical, and regulatory considerations for veterinary pathologists and toxicologists related to the design and evaluation of regulatory toxicology studies supporting vaccine clinical trials. Much of the information in this document focuses on the development of prophylactic vaccines for infectious agents. Many of these considerations also apply to therapeutic vaccine development (such as vaccines directed against cancer epitopes); important differences will be identified in various sections as appropriate. The topics addressed in this Points to Consider article include regulatory guidelines for nonclinical vaccine studies, study design (including species selection), technical considerations in dosing and injection site collection, study end point evaluation, and data interpretation. The intent of this publication is to share learnings related to nonclinical studies to support vaccine development to help others as they move into this therapeutic area. [Box: see text]
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- 2019
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12. Hybrid computational pregnant female phantom construction for radiation dosimetry applications
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Rasha Makkia, Keith Nelson, Habib Zaidi, and Michael Dingfelder
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Phantoms, Imaging ,computational phantom ,Placenta ,MODELS ,fetus ,NURBS ,Pregnancy ,pregnant ,Humans ,Female ,Pregnant Women ,EXPOSURE ,Radiometry ,FETAL ,General Nursing - Abstract
The number of patients undergoing diagnostic radiology and radiation therapy procedures has increased drastically owing to improvements in cancer diagnosis and treatment, and consequently, patient survival. However, the risk of secondary malignancies owing to radiation exposure remains a matter of concern. We previously published three hybrid computational fetal phantoms, which contained 27 fetal organs, as a starting point for developing the whole hybrid computational pregnant phantom set, which is the final objective of this study. An International Commission on Radiological Protection (ICRP) reference female voxel model was converted to a non-uniform rational B-spline (NURBS) surface model to construct a hybrid computational female phantom as a pregnant mother for each fetal model. Both fetal and maternal organs were matched with the ICRP- 89 reference data. To create a complete standard pregnant computational phantom set at 20, 30, and 35 weeks of pregnancy, the model mother’s reproductive organs were removed, and fetal phantoms with appropriate placental and uterine models were added to the female pelvis using a 3D-modeling software. With the aid of radiological image sets that had originally been used to construct the fetal models, each fetal position and rotation inside the uterus were carefully adjusted to represent the real fetal locations inside the uterus. The major abdominal soft tissue organs below the diaphragm, namely the small intestine, large intestine, liver, gall bladder, stomach, pancreas, uterus, and urinary bladder, were removed from non-pregnant females. The resulting fetal phantom was positioned in the appropriate location, matching the original radiological image sets. An obstetrician-gynecologist reviewed the complete internal anatomy of all fetus phantoms and the pregnant women for accuracy, and suggested changes were implemented as needed. The remaining female anatomical tissues were reshaped and modified to accommodate the location of the fetus inside the uterus. This new series of hybrid computational pregnant phantom models provides realistic anatomical details that can be useful in evaluating fetal radiation doses in pregnant patients undergoing diagnostic imaging or radiotherapy procedures where realistic fetal computational human phantoms are required.
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- 2022
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13. Mucocutaneous Squamous Cell Carcinoma in a Yucatan Minipig
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Keith Nelson, Randall Pielemeier, Andrew Petticoffer, Shane Thellman, and Sarah E Coe
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Pathology ,medicine.medical_specialty ,Skin Neoplasms ,040301 veterinary sciences ,Swine ,Mucocutaneous zone ,Toxicology ,Yucatan Minipig ,Pathology and Forensic Medicine ,0403 veterinary science ,Toxicology studies ,030207 dermatology & venereal diseases ,03 medical and health sciences ,0302 clinical medicine ,Keratin ,medicine ,Neoplasm ,Animals ,Basal cell ,Molecular Biology ,Skin ,chemistry.chemical_classification ,business.industry ,04 agricultural and veterinary sciences ,Cell Biology ,medicine.disease ,stomatognathic diseases ,Lymphatic system ,chemistry ,Carcinoma, Squamous Cell ,Swine, Miniature ,business ,Mucocutaneous junction - Abstract
Minipigs are commonly utilized in dermal toxicology studies, necessitating documentation of background findings, including neoplastic lesions. We describe a case of a Yucatan minipig with a squamous cell carcinoma at the mucocutaneous junction of the lip. The neoplasm appeared grossly as a slightly raised area of skin with ulceration. Histologically, there were nests and trabeculae of neoplastic squamous epithelial cells undergoing keratinization. Multifocally, rafts of these cells were within lymphatic vessels. Squamous cell carcinoma has not previously been reported in Yucatan or other laboratory minipigs, however, has been reported uncommonly in nonlaboratory pot-bellied pigs. Although squamous cell carcinoma has been associated with ultraviolet exposure or papillomavirus in various species, this was unable to be confirmed in this case.
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- 2021
14. Scheduling of reproduction in relation to molting and growth in malacostracan crustaceans
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Keith Nelson
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Scheduling (production processes) ,Zoology ,Biology ,biology.organism_classification ,Moulting ,Crustacean - Published
- 2020
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15. A TECHNOLOGY UPDATE IN WIRELINE FORMATION TESTING
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Simon Edmundson, Lina Xu, Tamim Sawaf, Keith Nelson, Thomas Pfeiffer, Deo Dindial, Ashers Partouche, Bo Yang, Hua Chen, and Chen Tao
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business.industry ,Computer science ,Wireline ,business ,Computer network - Published
- 2020
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16. Applications of Wireline Formation Testing: A Technology Update
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Chen Tao, Thomas Pfeiffer, Lina Xu, Ashers Partouche, Tamim Sawaf, Deo Dindial, Simon Edmundson, Keith Nelson, Bo Yang, and Hua Chen
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020401 chemical engineering ,business.industry ,Reservoir evaluation ,Wireline ,Systems engineering ,02 engineering and technology ,0204 chemical engineering ,010502 geochemistry & geophysics ,business ,01 natural sciences ,Automation ,Geology ,0105 earth and related environmental sciences - Abstract
Wireline formation testing has evolved from discrete pressure measurements, introduced in the 1950s to measuring pressure gradients and fluid contacts since the 1970s. Technology introduced in the late 1980s and onwards added interval pressure transient testing, focused sampling, and downhole fluid analysis. Thirty years later, this paper shows data examples of a recently developed formation testing platform in a wide range of environments, and applications, that change how we plan, acquire, and use formation testing. The dual-flow-line architecture of the formation testing platform is designed to systematically address shortcomings of legacy technology, enabling focused sampling in the tightest conventional formations, as well as transient testing in high mobility environments. Specialized pre-job planning software evaluates conveyance options to minimize friction and borehole contact, estimates the available flow rate, compares cleanup performance of the different inlets, and simulates transient testing responses. During the operation, the platform uses hardware embedded automation algorithms that execute routine tasks in a consistent and highly efficient manner, leaving more time for the user to focus on data quality and value of the measurements. Case studies from Mexico, Norway, and the US demonstrate specific improvements in capability and performance. Field data from Mexico shows focused sampling of gas condensate from a heterogeneous submillidarcy carbonate formation in an HP/HT well drilled with oil-based mud. Controlled downhole decompression of crude oil in the flowline at a sampling station in Norway enabled real-time measurement of its bubblepoint pressure to within 6 psi of that measured in the laboratory. Another case study integrates accurate relative asphaltene gradients into an existing reservoir fluid study to prove reservoir connectivity across a large lateral distance in a producing field. Application of the dual packer subsystem demonstrates inflation within four minutes and pure oil samples within 90 minutes on station in a 1.5-md/cp fractured basement formation. The fine pump control at a low rate enabled sampling just below reservoir pressure in Alaska and a case from the Gulf of Mexico demonstrates the real-time impact of fluid properties on the understanding of reservoir architecture and completion design. The presented examples highlight the impact of downhole automation, define the new operating envelope for formation testing in the most challenging environments, and highlight how the technology development leads to decision making on a broad reservoir scale by providing contextual answers rather than an accumulation of facts and figures.
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- 2020
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17. A Comonomer Strategy for Triggered Degradation and Re/Upcycling of High-Performance Thermoset Plastics
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Jeremiah Johnson, Desiree Plata, Keith Nelson, Yuchen Sun, David Veysset, Jet Lem, David Lundberg, Boya Xiong, Samantha Kristufek, Keith Husted, Wenxu Zhang, and Peyton Shieh
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Thermosets play a key role in the modern plastics and rubber industries, comprising ~18% of polymeric materials with a worldwide annual production of 65 million tons. The high density of crosslinks that give these materials their useful properties comes at the expense of facile degradability and re/upcyclability. Here, using the high-performance industrial thermoset plastic poly-dicyclopentadiene (pDCPD) as a model system, we show that when a small number of cleavable bonds are selectively installed within the strands of thermoset plastics using a low-cost comonomer approach, the resulting materials display the same exceptional properties as the native material yet they can undergo triggered degradation to yield soluble, re/upcyclable products of controlled size and functionality. In contrast, installation of cleavable crosslinks, even at comparably high loadings, does not produce degradable materials. These findings shed new light on the topology of polymer networks, revealing cleavable bond location as a universal design principle for controlled thermoset degradation and re/upcycling.
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- 2019
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18. Polymer nanodielectrics—Short history and future perspective
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Linda S. Schadler and J. Keith Nelson
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010302 applied physics ,Future perspective ,Computer science ,Scientific discovery ,General Physics and Astronomy ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Critical research ,01 natural sciences ,Toolbox ,Field (computer science) ,Resource (project management) ,Risk analysis (engineering) ,0103 physical sciences ,Key (cryptography) ,0210 nano-technology - Abstract
This article provides a perspective on the development of polymer nanodielectrics for electrical insulation applications. It includes a short history of the development of the field, barriers to implementation, a chemical toolbox available for optimizing properties, some examples of potential commercial development, and the latest advances. It offers opinions on critical research needed to fully develop the models needed to predict the behavior and to develop design tools. Key findings include the need for quantification of nanofiller dispersion, investment in long term aging data research, better scale-up methods, a data resource that brings the broad data together in a format that enables faster scientific discovery, and a commercial entity willing to take the risk in implementing these promising materials.
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- 2020
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19. LESSONS LEARNED FROM A QUARTER CENTURY OF GROUNDWATER MANAGEMENT IN THE SANTA CRUZ ACTIVE MANAGEMENT AREA
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Keith Nelson
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Geography ,Management area ,Groundwater management ,Archaeology ,Quarter century - Published
- 2019
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20. Interpersonal Approaches to Coaching
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Keith Nelson
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business.industry ,Applied psychology ,Interpersonal communication ,Psychology ,business ,Coaching - Published
- 2018
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21. Practical Strategies for Navigating Toxicologic Pathology in One's Early Career…and Beyond!
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Vinicius Carreira, Keith Nelson, Stacey Fossey, Lila Ramaiah, Kenneth A Schafer, Bevin Zimmerman, Erin Quist, and Gopinath S. Palanisamy
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Pathology ,medicine.medical_specialty ,040301 veterinary sciences ,education ,Toxicology ,030226 pharmacology & pharmacy ,Pathology and Forensic Medicine ,0403 veterinary science ,03 medical and health sciences ,Veterinary pathologist ,0302 clinical medicine ,medicine ,Humans ,Early career ,Molecular Biology ,Pharmaceutical industry ,Career Choice ,business.industry ,Public health ,04 agricultural and veterinary sciences ,Cell Biology ,Outreach ,Psychology ,business ,Career development - Abstract
The toxicologic pathologist plays a vital role in the scientific community, using their unique blend of diagnostic and investigative skills to advance biomedical research, public health, drug discovery, or regulatory practices. But what exactly do toxicologic pathologists contribute? Where do these specialized professionals work? How can toxicologic pathologists maximize their efficiency and potential? To enlighten students and trainees, as well as early- or mid-career toxicologic pathologists, or even those approaching retirement, the Career Development and Outreach Committee of the Society of Toxicologic Pathology (STP) sponsored a career development workshop entitled “Practical Strategies for Navigating Toxicologic Pathology in One’s Early Career…and Beyond!” in conjunction with the STP 37th annual symposium. The workshop featured toxicologic pathologists from contract research organizations and the pharmaceutical industry, who provided their perspectives on career preparation, evolving veterinary pathologist roles within various sectors of toxicologic pathology, the fundamentals of safety assessment, logistics of projects involving good laboratory practices, tools for effective interpretation and communication of anatomic and clinical pathology results, and a recap of scientific resources available to support the toxicologic pathologist in his or her journey. This article provides brief summaries of the talks presented during this career development workshop.
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- 2018
22. Low Frequency Dielectric Response of Silicone/ZrO2 Nanocomposites
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Shaohua Li, Aditya Prasad, Yanfeng Gao, J. Keith Nelson, Linda S. Schadler, and Xidong Liang
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010302 applied physics ,Permittivity ,Nanocomposite ,Materials science ,Polydimethylsiloxane ,Nanoparticle ,Relative permittivity ,02 engineering and technology ,Dielectric ,021001 nanoscience & nanotechnology ,01 natural sciences ,chemistry.chemical_compound ,Silicone ,chemistry ,0103 physical sciences ,Dispersion (optics) ,Composite material ,0210 nano-technology - Abstract
To understand the influence of nanofillers on the dielectric spectra of nanocomposites, this paper examines the low frequency dielectric responses for silicone/ZrO 2 nanocomposites with different filler loadings. The ZrO 2 nanoparticles were grafted with 1k and 10k molecular weight polydimethylsiloxane (PDMS) in order to achieve good dispersion in the PDMS matrix. The relative permittivity at infinite frequency and dc conductance were calculated through Kramers-Kronig relations and successfully differentiated from the measured spectra. The influence of temperature and filler loading on these two parameters and the shape of dielectric spectra is discussed.
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- 2018
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23. Pathways to Self-healing Nanodielectrics
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Steve Eckroad, Michael Goodman, Atri Rungta, Chris Calebrese, Brian C. Benicewicz, J. Keith Nelson, and Linda S. Schadler
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010302 applied physics ,chemistry.chemical_classification ,Nanocomposite ,Materials science ,Field (physics) ,0211 other engineering and technologies ,Nanoparticle ,Nanotechnology ,02 engineering and technology ,Polymer ,Dielectric ,01 natural sciences ,Stress (mechanics) ,chemistry ,Self-healing ,021105 building & construction ,0103 physical sciences ,Partial discharge - Abstract
This contribution examines a number of possibilities for achieving a measure of self-healing in dielectric structures locally damaged by being subjected to electrical stresses. The principle explored is the use of agencies which can be activated by the presence of photon irradiation arising from internal discharges due to field concentrations or gaseous inclusions. It is suggested that nanoparticles can provide a vehicle for introducing active moieties into a polymer nanodielectric through surface ligands already demonstrated to bring about electric strength enhancements. Preliminary results for one of these possibilities are provided in which photon-activated cross-linking is stimulated in an epoxy-SiO 2 nanocomposite subjected to partial discharge.
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- 2018
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24. An infant formula toxicity and toxicokinetic feeding study on carrageenan in preweaning piglets with special attention to the immune system and gastrointestinal tract
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Brandon M. Zeigler, Brinda Mahadevan, Keith Nelson, L. Cochrane, Bjorn A. Thorsrud, W.R. Blakemore, A. Brant, Myra L. Weiner, M. Pellerin, H.E. Ferguson, and Mark Cameron
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Male ,Swine ,Interleukin-1beta ,Physiology ,Carrageenan ,Toxicology ,chemistry.chemical_compound ,Immunophenotyping ,Immune system ,Lactation ,Toxicity Tests ,medicine ,Animals ,Cytotoxic T cell ,Gastrointestinal tract ,Dose-Response Relationship, Drug ,Interleukin-6 ,Tumor Necrosis Factor-alpha ,business.industry ,Body Weight ,Interleukin-8 ,Organ Size ,General Medicine ,Infant Formula ,Gastrointestinal Tract ,medicine.anatomical_structure ,Animals, Newborn ,Infant formula ,chemistry ,Immune System ,Immunology ,Toxicity ,Female ,business ,Food Science - Abstract
A toxicity/toxicokinetic swine-adapted infant formula feeding study was conducted in Domestic Yorkshire Crossbred Swine from lactation day 3 for 28 consecutive days during the preweaning period at carrageenan concentrations of 0, 300, 1000 and 2250 ppm under GLP guidelines. This study extends the observations in newborn baboons (McGill et al., 1977) to piglets and evaluates additional parameters: organ weights, clinical chemistry, special gastrointestinal tract stains (toluidine blue, Periodic Acid-Schiff), plasma levels of carrageenan; and evaluation of potential immune system effects. Using validated methods, immunophenotyping of blood cell types (lymphocytes, monocytes, B cells, helper T cells, cytotoxic T cells, mature T cells), sandwich immunoassays for blood cytokine evaluations (IL-6, IL-8, IL1β, TNF-α), and immunohistochemical staining of the gut for IL-8 and TNF-α were conducted. No treatment-related adverse effects at any carrageenan concentration were found on any parameter. Glucosuria in a few animals was not considered treatment-related. The high dose in this study, equivalent to ~430 mg/kg/day, provides an adequate margin of exposure for human infants, as affirmed by JECFA and supports the safe use of carrageenan for infants ages 0-12 weeks and older and infants with special medical needs.
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- 2015
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25. Preparation of BaTiO3/low melting glass core–shell nanoparticles for energy storage capacitor applications
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Douglas B. Chrisey, Minoru Tomozawa, Xiaofeng Su, Brian C. Riggs, and J. Keith Nelson
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Nanocomposite ,Materials science ,Renewable Energy, Sustainability and the Environment ,Borosilicate glass ,Nanoparticle ,Sintering ,chemistry.chemical_element ,General Chemistry ,Dielectric ,Porous glass ,Bismuth ,Grain growth ,chemistry ,General Materials Science ,Composite material - Abstract
A core–shell nano-scale mixing technique was applied to fabricate BaTiO3/glass nanocomposites in order to preserve the nano-grain dielectric properties of BaTiO3 after sintering and enhance the bulk composite energy storage capability. Coating layers of low melting glasses of lead borosilicate glass (65PbO–20B2O3–15SiO2, mol%) and bismuth borosilicate glass (65Bi2O3–20B2O3–15SiO2, mol%) were deposited onto BaTiO3 nanoparticles in chemical solution by a sol-precipitation method under ultrasonic agitation. Transmission electron microscopy (TEM) results confirmed the formation of core–shell nanostructures with controllable shell thicknesses between 2 and 18 nm. X-ray diffraction (XRD) patterns showed that no crystalline peaks were detected from the glass coating layer. Fourier transform infrared (FT-IR) spectra indicated a glass network structure of lead borosilicate glass and bismuth borosilicate glass, respectively. High densifications were achieved for both composites by sintering at low temperatures (≤900 °C). Noticeable grain growth was observed for the lead borosilicate glass-coated BaTiO3 (Pb-BT) composite while almost no grain growth was observed for the bismuth borosilicate glass-coated BaTiO3 (Bi-BT) nanocomposite. This disparity was attributed to the different interactions between the BaTiO3 core and two glasses during the sintering process, as revealed by the XRD study. Dielectric properties and energy storage capability of the Bi-BT nanocomposite were investigated in detail. The Bi-BT nanocomposite showed high polarization, high dielectric breakdown strength (≥1000 kV cm−1), postponed polarization saturation, and low remnant polarization with the discharge energy density of ∼10 J cm−3 at 1000 kV cm−1. Thus, the Bi-BT core–shell nanocomposite appears to be a promising material system for energy storage capacitor applications.
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- 2014
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26. Papillomavirus-associated Cutaneous Papillomas in a Population of Wild Spotted Hyenas (Crocuta crocuta)
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Keith Nelson, Anne L. Engh, Christy A. McKnight, Annabel Rector, Annabel G. Wise, Roger K. Maes, Andrew S. Flies, Karlien De Keyser, Kay E. Holekamp, Matti Kiupel, Hans Stevens, Elisabeth Heylen, Marc Van Ranst, Nelson, Keith G, Engh, Anne L, McKnight, Christy A, Kiupel, Matti, Wise, Annabel G, Maes, Roger K, Stevens, Hans, Heylen, Elisabeth, de Keyser, Karlien, Rector, Annabel, Van Ranst, Marc, Flies, Andrew Steven, and Holekamp, Kay E
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Male ,Pathology ,medicine.medical_specialty ,Skin Neoplasms ,Stratum granulosum ,Population ,Animals, Wild ,virus ,Crocuta crocuta ,papillomavirus ,Species Specificity ,biology.animal ,medicine ,Animals ,Papillomaviridae ,Stratum spinosum ,education ,Ecology, Evolution, Behavior and Systematics ,education.field_of_study ,integumentary system ,Ecology ,biology ,Papillomavirus Infections ,hyaenidae ,biology.organism_classification ,medicine.disease ,Virology ,Koilocyte ,papilloma ,Hyena ,medicine.anatomical_structure ,spotted hyena ,crocuta crocuta ,Papilloma ,Female ,Hyaenidae - Abstract
Beginning in 1997 Michigan State University Mara Hyena Project investigators observed waxing and waning progression of oral and genital masses during long-term behavioral observations of a population of wild spotted hyenas (Crocuta crocuta) from the Masai Mara Game Reserve, Kenya. From 1999-2000, we darted adult spotted hyenas to obtain routine physiologic and hematologic data and collected small, raised, lobulated, pigmented masses from the oral or genital areas of eight animals. Microscopically, masses consisted of variably thickened epidermis with thick elongate rete pegs, prominent stratum spinosum, and few koilocytes, consistent with papillomavirus-induced lesions. Immunohistochemistry on formalin-fixed, paraffin-embedded papilloma tissue revealed positive intranuclear labeling for papillomavirus antigen in the superficial stratum granulosum and in sloughing keratin layers of multiple samples. Polymerase chain reaction on DNA extracts from tumor tissue amplified a papillomavirus-specific 418 base pair amplicon in the E1 ORF. Basic Local Alignment Search Tool analysis of the sequenced amplicon suggests a novel hyaenid papillomavirus. Confirmatory complete genomic sequencing was performed later by the Rega Institute in Belgium. To our knowledge, this is the first report of a papillomavirus in a Hyaenidae species. Spotted hyena social behavior might facilitate oral-genital transmission of papillomavirus in this population. Refereed/Peer-reviewed
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- 2013
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27. The influence of moisture on the electrical properties of crosslinked polyethylene/silica nanocomposites
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Linda S. Schadler, J. Keith Nelson, and L. Hui
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chemistry.chemical_compound ,Materials science ,Nanocomposite ,Moisture ,chemistry ,Percolation ,Particle ,Dielectric ,Electrical and Electronic Engineering ,Composite material ,Polyethylene ,Dispersion (chemistry) ,Polyolefin - Abstract
Crosslinked polyethylene (XLPE)/silica nanocomposites are promising candidates for future cable insulation. While a significant number of studies have demonstrated improved dielectric properties in nanocomposites compared to XLPE, the performance of polyolefin nanocomposites in humid environments has not received much attention. This paper presents and explains the dielectric behavior of XLPE/silica nanocomposites in humid environments such as the decrease in AC breakdown strength, increases in loss and space charge formation, and the significant reduction in water tree aging. XLPE/silica nanocomposites are found to have an increased moisture uptake compared to the XLPE base polymer due to inclusion of silica particles. It is hypothesized that the formation of a concentric shell surrounding the particle with a high concentration of water (water shell), and the change in the inter-particle/cluster distances are two major factors governing the dielectric behavior in wet XLPE/silica nanocomposites. The dispersion and distribution of the nanofillers were quantified using a new tool and a method to reconstruct the 3D structure was used to determine the size of the water shell required for percolation. It was found that a water layer thickness of tens of nanometers could initiate percolation in the XLPE/silica nanocomposites studied. Notwithstanding that, water tree growth was substantially reduced in the XLPE/silica nanocomposites, and some speculative explanations are provided on the basis of the characteristics observed.
- Published
- 2013
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28. Dielectric constant and breakdown strength of polymer composites with high aspect ratio fillers studied by finite element models
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Henrik Hillborg, J. Keith Nelson, Linda S. Schadler, Zepu Wang, and Su Zhao
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Permittivity ,chemistry.chemical_classification ,Filler (packaging) ,Materials science ,Composite number ,General Engineering ,Polymer ,Dielectric ,Condensed Matter::Materials Science ,chemistry ,Electric field ,Ceramics and Composites ,Grain boundary ,Fiber ,Composite material - Abstract
A finite element model was used to study the dielectric constant and breakdown strength of polymer composite filled with high aspect ratio fillers. The impact of composite microstructure and filler aspect ratio on the dielectric properties was investigated. The results were used to explain the experimental data for BaTiO 3 fiber filled poly(dimethyl siloxane) published previously. The effect of filler shape, aspect ratio distribution, curvature, grain boundary and alignment on the composite permittivity was studied. A model was proposed to correlate the composite microstructure, the electric field distribution in the polymer matrix, and the dielectric breakdown strength of composites.
- Published
- 2013
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29. Effect of crystallizable glass addition on sintering and dielectric behaviors of barium titanate ceramics
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J. Keith Nelson, Minoru Tomozawa, Xiaofeng Su, and Douglas B. Chrisey
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Materials science ,Composite number ,Sintering ,Dielectric ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention ,chemistry.chemical_compound ,chemistry ,law ,visual_art ,Phase (matter) ,Barium titanate ,visual_art.visual_art_medium ,Ceramic ,Electrical and Electronic Engineering ,Composite material ,Crystallization ,High-κ dielectric - Abstract
A crystallizable glass which can precipitate barium titanate was added to BaTiO3 ceramics to study its effect on sintering behavior and dielectric properties of the composites. High densification (>95 % theoretical density) was achieved by addition of glass phase and the dielectric constant of composites was enhanced through the crystallization of glass phase. A composite with 90 wt% BaTiO3 and 10 wt% glass showed a dielectric constant of ~2,300 at room temperature at 1 kHz and a dielectric breakdown strength about 140 kV/cm.
- Published
- 2013
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30. Investigation of dielectric breakdown in silica-epoxy nanocomposites using designed interfaces
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Ke Wu, Henrik Hillborg, J. Keith Nelson, Timothy M. Krentz, Su Zhao, Michael Bell, Curt M. Breneman, Linda S. Schadler, and Brian C. Benicewicz
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Glycidyl methacrylate ,Nanocomposite ,Materials science ,Dielectric strength ,02 engineering and technology ,Epoxy ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,Avalanche breakdown ,0104 chemical sciences ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Biomaterials ,chemistry.chemical_compound ,Colloid and Surface Chemistry ,Terthiophene ,chemistry ,Chemical engineering ,visual_art ,Polymer chemistry ,visual_art.visual_art_medium ,Surface modification ,0210 nano-technology ,Dispersion (chemistry) - Abstract
Adding nano-sized fillers to epoxy has proven to be an effective method for improving dielectric breakdown strength (DBS). Evidence suggests that dispersion state, as well as chemistry at the filler-matrix interface can play a crucial role in property enhancement. Herein we investigate the contribution of both filler dispersion and surface chemistry on the AC dielectric breakdown strength of silica-epoxy nanocomposites. Ligand engineering was used to synthesize bimodal ligands onto 15nm silica nanoparticles consisting of long epoxy compatible, poly(glycidyl methacrylate) (PGMA) chains, and short, π-conjugated, electroactive surface ligands. Surface initiated RAFT polymerization was used to synthesize multiple graft densities of PGMA chains, ultimately controlling the dispersion of the filler. Thiophene, anthracene, and terthiophene were employed as π-conjugated surface ligands that act as electron traps to mitigate avalanche breakdown. Investigation of the synthesized multifunctional nanoparticles was effective in defining the maximum particle spacing or free space length (Lf) that still leads to property enhancement, as well as giving insight into the effects of varying the electronic nature of the molecules at the interface on breakdown strength. Optimization of the investigated variables was shown to increase the AC dielectric breakdown strength of epoxy composites as much as 34% with only 2wt% silica loading.
- Published
- 2016
31. Morphologically dependent alternating-current and direct-current breakdown strength in silica-polypropylene nanocomposites
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Henrik Hillborg, Mohammad M. Khani, Linda S. Schadler, J. Keith Nelson, Timothy M. Krentz, Brian C. Benicewicz, Su Zhao, and Michael Bell
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010302 applied physics ,Polypropylene ,chemistry.chemical_classification ,Materials science ,Nanocomposite ,Polymers and Plastics ,Nanoparticle ,02 engineering and technology ,General Chemistry ,Polymer ,021001 nanoscience & nanotechnology ,Polymer brush ,01 natural sciences ,Surfaces, Coatings and Films ,chemistry.chemical_compound ,chemistry ,0103 physical sciences ,Materials Chemistry ,Particle ,Surface modification ,Composite material ,0210 nano-technology ,Dispersion (chemistry) - Abstract
In this article, we report the synthesis of a new bimodal surface ligand morphology on silica nanoparticles. Combining grafting-to and grafting-from approaches, in this study, we demonstrated the efficacy of anthracene surface modification for improving the dielectric breakdown strength (DBS) under alternating-current and direct-current conditions and that of a matrix-compatible polymer brush for controlling the nanofiller (NF) dispersion. Ligand-modified spherical colloidal SiO2 nanoparticles (∼14 nm in diameter) were mixed into polypropylene, and the resulting dispersion was improved over the unmodified particles, as shown with transmission electron microscopy. The results suggest that the electronic structure of the anthracene-modified particle surface was critical to the improvement in DBS. In addition, the DBS of the composite was shown to depend on the dispersion state of the filler and the mode of stress; this indicated that the individually dispersed nanoparticles were not necessarily the optimal morphology for all stress conditions. Additionally, the precise nature of the matrix-compatible brush was less important than the NF dispersion it produced. The bimodal grafted architectural design has provided a promising solution for the control of the dispersion and surface properties, especially for high-molecular-weight polymer matrices. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44347.
- Published
- 2016
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32. Cloud computing for integrated stochastic groundwater uncertainty analysis
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Keith Nelson, Wesley E. Hipke, Alexander Y. Sun, and Yong Liu
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Service (systems architecture) ,Stochastic modelling ,business.industry ,Computer science ,Usability ,Cloud computing ,Scientific modelling ,computer.software_genre ,Computer Science Applications ,Cyberinfrastructure ,General Earth and Planetary Sciences ,Use case ,Data mining ,Software engineering ,business ,Conjunctive use ,computer ,Software - Abstract
One of the major scientific challenges and societal concerns is to make informed decisions to ensure sustainable groundwater availability when facing deep uncertainties. A major computational requirement associated with this is on-demand computing for risk analysis to support timely decision. This paper presents a scientific modeling service called ‘ModflowOnAzure’ which enables large-scale ensemble runs of groundwater flow models to be easily executed in parallel in the Windows Azure cloud. Several technical issues were addressed, including the conjunctive use of desktop tools in MATLAB to avoid license issues in the cloud, integration of Dropbox with Azure for improved usability and ‘Drop-and-Compute,’ and automated file exchanges between desktop and the cloud. Two scientific use cases are presented in this paper using this service with significant computational speedup. One case is from Arizona, where six plausible alternative conceptual models and a streamflow stochastic model are used to eva...
- Published
- 2012
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33. The Safety of EXPAREL ® (Bupivacaine Liposome Injectable Suspension) Administered by Peripheral Nerve Block in Rabbits and Dogs
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Marlon C. Rebelatto, Phaedra I. Cole, Paul E. Ross, Brigitte M. Richard, Abram N. Brubaker, Keith Nelson, Dean Haan, Laura R. Ott, and Paul E. Newton
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Bupivacaine ,medicine.medical_specialty ,Article Subject ,Nerve root ,Clinical pathology ,business.industry ,medicine.medical_treatment ,lcsh:RS1-441 ,Adipose tissue ,Surgery ,lcsh:Pharmacy and materia medica ,Pharmacokinetics ,Anesthesia ,medicine ,Histopathology ,business ,Saline ,Brachial plexus ,Research Article ,medicine.drug - Abstract
A sustained-release DepoFoam injection formulation of bupivacaine (EXPAREL, 15 mg/mL) is currently being investigated for postsurgical analgesia via peripheral nerve block (PNB). Single-dose toxicology studies of EXPAREL (9, 18, and 30 mg/kg), bupivacaine solution (Bsol, 9 mg/kg), and saline injected around the brachial plexus nerve bundle were performed in rabbits and dogs. The endpoints included clinical pathology, pharmacokinetics, and histopathology evaluation on Day 3 and Day 15 (2/sex/group/period). EXPAREL resulted in a nearly 4-fold lower Cmax versus Bsol at the same dose. EXPAREL was well tolerated at doses up to 30 mg/kg. The only EXPAREL-related effect seen was minimal to mild granulomatous inflammation of adipose tissue around nerve roots (8 of 24 rabbits and 7 of 24 dogs) in the brachial plexus sites. The results indicate that EXPAREL was well tolerated in these models and did not produce nerve damage after PNB in rabbits and dogs.
- Published
- 2012
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34. Safety Evaluation of EXPAREL (DepoFoam Bupivacaine) Administered by Repeated Subcutaneous Injection in Rabbits and Dogs: Species Comparison
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Dean Haan, Phaedra I. Cole, Douglas E. Rickert, Paul E. Ross, Brigitte M. Richard, Keith Nelson, Paul E. Newton, Laura R. Ott, Marlon C. Rebelatto, and Abram N. Brubaker
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Bupivacaine ,Article Subject ,business.industry ,lcsh:RS1-441 ,Pharmacology ,3. Good health ,lcsh:Pharmacy and materia medica ,Granulomatous inflammation ,03 medical and health sciences ,Subcutaneous injection ,0302 clinical medicine ,030202 anesthesiology ,Toxicity ,Bupivacaine hcl ,medicine ,business ,030217 neurology & neurosurgery ,Research Article ,medicine.drug - Abstract
EXPAREL (bupivacaine extended-release liposome injection), DepoFoam bupivacaine, is in development for prolonged postsurgical analgesia. Repeat-dose toxicity studies were conducted in rabbits and dogs to compare the potential local and systemic toxicities of EXPAREL and bupivacaine HCl (Bsol), and the reversibility of any effects. Dogs tolerated much larger doses than rabbits. EXPAREL-related minimal-to-moderate granulomatous inflammation was noted at the injection sites. In recovery animals, the granulomatous inflammation was observed less frequently and was characterized by an increased number of multinucleated giant cells. These effects were considered a normal response to liposomes and nonadverse. Rabbits are more sensitive than dogs. In rabbits, convulsions were noted with EXPAREL and more frequently with Bsol; a NOAEL was not identified. In dogs, EXPAREL was well tolerated (NOAEL > 30 mg/kg/dose). The cumulative exposure of EXPAREL in these studies is well in excess of the proposed maximum single-dose exposure that is intended in humans.
- Published
- 2011
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35. Chemical and Mechanistic Toxicology Evaluation of Exon Skipping Phosphorodiamidate Morpholino Oligomers in mdx Mice
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Keith Nelson, Peter Sazani, Doreen L. Weller, and Stephen B. Shrewsbury, Duane W. Poage, and Kirk P. Van Ness
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musculoskeletal diseases ,congenital, hereditary, and neonatal diseases and abnormalities ,mdx mouse ,biology ,Morpholino ,Duchenne muscular dystrophy ,Oligonucleotides ,Exons ,Organ Size ,Pharmacology ,Toxicology ,medicine.disease ,Molecular biology ,Exon skipping ,Morpholinos ,Mice ,Exon ,Basophilia ,Toxicity ,Mice, Inbred mdx ,biology.protein ,medicine ,Animals ,Dystrophin - Abstract
AVI-4658 is a phosphorodiamidate morpholino oligomer (PMO) designed to induce skipping of dystrophin exon 51 and restore its expression in patients with Duchenne muscular dystrophy (DMD). Preclinically, restoration of dystrophin in the dystrophic mdx mouse model requires skipping of exon 23, achieved with the mouse-specific PMO, AVI-4225. Herein, we report the potential toxicological consequences of exon skipping and dystrophin restoration in mdx mice using AVI-4225. We also evaluated the toxicological effects of AVI-4658 in both mdx and wild-type mice. In both studies, animals were dosed once weekly for 12 weeks up to the maximum feasible dose of 960 mg/kg per injection. Both AVI-4658 and AVI-4225 were well-tolerated at all doses. Findings in AVI-4225-treated animals were generally limited to mild renal tubular basophilia/vacuolation, without any significant changes in renal function and with evidence of reversing. No toxicity associated with the mechanism of action of AVI-4225 in a dystrophic animal was observed.
- Published
- 2011
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36. Explorations of Détente
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Keith Nelson
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History ,Law ,Environmental ethics - Published
- 2011
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37. A field assessment of PD and EMI methodology applied to large utility generators
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Jan Stein and J. Keith Nelson
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Engineering ,business.industry ,Stator ,Electric generator ,Condition monitoring ,Electromagnetic interference ,law.invention ,Reliability engineering ,Generator (circuit theory) ,law ,EMI ,Frequency domain ,Partial discharge ,Electronic engineering ,Electrical and Electronic Engineering ,business - Abstract
Results and assessment are provided from a nearly 10 year study of the application of a variety of diagnostic methods applied to the condition monitoring of generator stator insulation. The methods studied included various forms of Partial Discharge (PD) techniques and Electromagnetic Interference (EMI) in the frequency domain. The condition of a number of operating machines was tracked by the various techniques and, in most cases, the findings compared with the actual condition determined by subsequent inspection after the rotors had been removed. This has permitted the effectiveness of the various methods to be gauged and allowed an appraisal of the attendant best practices and pitfalls.
- Published
- 2010
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38. Growth Differences Among Families Of The Lobster, Homarus americanus1
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Dennis Hedgecock, Keith Nelson, and Robert A. Shleser
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Homarus ,Animal science ,biology ,Ecology ,Brine shrimp ,Aquatic Science ,biology.organism_classification ,Full Sibling ,Genetic stock ,Selective breeding ,Agronomy and Crop Science ,Rank correlation - Abstract
Results of a pilot study designed to estimate the variance of growth rates within and between full sibling families of the lobster Homarus americanus are presented. Progenies raised simultaneously for 100 days under optimal temperature (˜21 C) and diet (live, adult brine shrimp fed ad libitum) grow at significantly different rates. Pronounced environmental effects on growth are inferred from an inverse rank correlation (rS = -0.91) between progeny mean growth rates and the temporal sequence with which progenies were introduced into the experimental space. Differences in growth rates between siblings grown in two independent, experimental seawater tables are also significant in some cases. Family x table interaction is observed indicating that growth may not always be predictable from knowledge of genetic stock and quality of the rearing system alone. Implications for selective breeding of faster growing lobsters are discussed.
- Published
- 2009
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39. GENETIC CONSIDERATIONS IN SELECTING CRUSTACEAN SPECIES FOR AQUACULTURE1
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Keith Nelson
- Subjects
Ecology ,Evolutionary biology ,Genetic variation ,Trait ,Biological dispersal ,Aquatic Science ,Adaptation ,Heritability ,Biology ,Domestication ,Mating system ,Agronomy and Crop Science ,Selection (genetic algorithm) - Abstract
The process of selection of species for aquaculture should include consideration of long-term genetic adaptability to conditions of culture (i.e., domestication) which are often very different from those prevailing in more natural environments. Major consideration should be given to the heritability of desirable traits such as growth rate, disease resistance, etc. Heritability may be defined as that proportion of the total variation of the trait under particular circumstances which may be attributed to additive genetic variance; it may be calculated from the results of experiments involving progenies of selected matings. In the absence of such data, one expects heritability to be higher in members of evolutionary flourishing and recently expanding groups in which there is great variation in the trait in question. Without genetic variation or heterozygosity there can be no selection; estimates of overall relative heterozygosity in populations of different species may be made from modern techniques of examination of protein variation. If within-population heterozygosity is low or negligible, hybridization between populations may increase heterozygosity and heritability; if populations within a species are not differentiated genetically, interspecific hybridization may be attempted. This approach is more likely to succeed with recently diverged species, such as are found again in evolutionary flourishing groups. Finally, it may be possible to speed up the process of adaptation to the conditions of culture and the market place by taking advantage of special features in the mating system (e.g., protandrous hermaphroditism), life history (e.g., metamorphosis), or population biology (e.g., dispersal phases) of the potential cultivar. Examples are given of these principles applied to candidate species.
- Published
- 2009
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40. PROGRESS AND PROBLEMS IN LOBSTER BROODSTOCK DEVELOPMENT
- Author
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W. Borgeson, W. L. Moffett, D. Hedgecock, and Keith Nelson
- Subjects
photoperiodism ,Homarus ,biology ,Ecology ,media_common.quotation_subject ,Broodstock ,Aquatic Science ,Animal husbandry ,biology.organism_classification ,Selective breeding ,Animal science ,Gammarus ,Reproduction ,Agronomy and Crop Science ,Moulting ,media_common - Abstract
A major impediment to commercial farming of the lobster Homarus is lack of control over reproduction. Without it, a steady supply of seed cannot be insured, nor can selective breeding be applied. The major block in the reproduction of either laboratory-mated or wild-caught inseminated females has been low frequency of egg extrusion. Prior to 1976, 5 extrusions were documented at the Bodega Marine Laboratory. Only one of these hatched successfully. Since late 1976, however, 10 females mated in the laboratory and 8 females inseminated in nature have successfully extruded. Of these ovigerous females, 5 hatched viable progenies and the remainder subsequently lost their eggs. Most of these reproductive events occurred during a 22-week experiment in which laboratory-mated and field-inseminated females were held in large tanks (37 cm × 74 cm × 49 cm deep) in a 3 temperature × 2 photoperiod design. Mortality was highest (5/18 or 28%) in the highest temperature schedule (18–22°C), lower (3/36 or 8%) in the middle temperature schedule (14–18°C) and zero (0/18) at lower temperatures (10–15°C). Molting followed a similar ordering, 67% at high temperatures, 64% at medium temperatures and 50% at low temperatures. The rate of extrusion showed an inverse pattern with only 6% in the high, 14% in the medium and 22% in the low temperature schedules. Photoperiod had an apparent effect only in the low temperature schedule with 2 molts in the short day and 7 in the long day cycle. Ovarian maturation was monitored during the experiment by a candling technique. Candling scores are correlated with actual ovary appearance and weight for 35 females sacrificed at the study's conclusion. Progress in broodstock development has come chiefly through better husbandry (larger tanks, varied diet, as well as improved sampling techniques and record keeping practices), and in part through the success of H. gammarus females in crosses to H. americanus males. Two overall results of significance to lobster broodstock development are the evidence of shorter than 2-year cycles in some females, and the lack of marked seasonality in reproductive activity. Two problems, in addition to understanding the complex interplay of molting and ovarian development, are shell disease and loss of eggs following extrusion.
- Published
- 2009
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41. Brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona and act as intermediate hosts
- Author
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Hany M. Elsheikha, Keith Nelson, Dwight D. Bowman, P.M. Gearhart, M.G. Rossano, Harold C. Schott, Alice J. Murphy, Jon S. Patterson, Linda S. Mansfield, Susan M. Tanhauser, S. Mehler, and B. Knust
- Subjects
Cowbird ,Pathology ,medicine.medical_specialty ,Sarcocystosis ,Polymerase Chain Reaction ,Sensitivity and Specificity ,Equine protozoal myeloencephalitis ,Host-Parasite Interactions ,Microbiology ,Songbirds ,Schizogony ,Interferon-gamma ,Mice ,Opossum ,parasitic diseases ,medicine ,Animals ,Parasite hosting ,Horses ,Muscle, Skeletal ,Phylogeny ,Skin ,Mice, Knockout ,General Veterinary ,biology ,Bird Diseases ,Intermediate host ,Sarcocystis ,Opossums ,General Medicine ,Ribosomal RNA ,biology.organism_classification ,Specific Pathogen-Free Organisms ,Parasitology ,Polymorphism, Restriction Fragment Length - Abstract
We tested the hypothesis that brown-headed cowbirds ( Molothrus ater ) harbor Sarcocystis neurona , the agent of equine protozoal myeloencephalitis (EPM), and act as intermediate hosts for this parasite. In summer 1999, wild caught brown-headed cowbirds were collected and necropsied to determine infection rate with Sarcocystis spp. by macroscopic inspection. Seven of 381 (1.8%) birds had grossly visible sarcocysts in leg muscles with none in breast muscles. Histopathology revealed two classes of sarcocysts in leg muscles, thin-walled and thick-walled suggesting two species. Electron microscopy showed that thick-walled cysts had characteristics of S. falcatula and thin-walled cysts had characteristics of S. neurona . Thereafter, several experiments were conducted to confirm that cowbirds had viable S. neurona that could be transmitted to an intermediate host and cause disease. Specific-pathogen-free opossums fed cowbird leg muscle that was enriched for muscle either with or without visible sarcocysts all shed high numbers of sporocysts by 4 weeks after infection, while the control opossum fed cowbird breast muscle was negative. These sporocysts were apparently of two size classes, 11.4 ± 0.7 μm by 7.6 ± 0.4 μm ( n = 25) and 12.6 ± 0.6 μm by 8.0 ± 0 μm ( n = 25). When these sporocysts were excysted and introduced into equine dermal cell tissue culture, schizogony occurred, most merozoites survived and replicated long term and merozoites sampled from the cultures with long-term growth were indistinguishable from known S. neurona isolates. A cowbird Sarcocystis isolate, Michigan Cowbird 1 (MICB1), derived from thin-walled sarcocysts from cowbirds that was passaged in SPF opossums and tissue culture went on to produce neurological disease in IFNγ knockout mice indistinguishable from that of the positive control inoculated with S. neurona . This, together with the knowledge that S. falcatula does not cause lesions in IFNγ knockout mice, showed that cowbird leg muscles had a Sarcocystis that fulfills the first aim of Koch's postulates to produce disease similar to S. neurona . Two molecular assays provided further support that both S. neurona and S. falcatula were present in cowbird leg muscles. In a blinded study, PCR-RFLP of RAPD-derived DNA designed to discriminate between S. neurona and S. falcatula showed that fresh sporocysts from the opossum feeding trial had both Sarcocystis species. Visible, thick-walled sarcocysts from cowbird leg muscle were positive for S. falcatula but not S. neurona ; thin-walled sarcocysts typed as S. neurona . In 1999, DNA was extracted from leg muscles of 100 wild caught cowbirds and subjected to a PCR targeting an S. neurona specific sequence of the small subunit ribosomal RNA (SSU rRNA) gene. In control spiking experiments, this assay detected DNA from 10 S. neurona merozoites in 0.5 g of muscle. In the 1999 experiment, 23 of 79 (29.1%) individual cowbird leg muscle samples were positive by this S. neurona -specific PCR. Finally, in June of 2000, 265 cowbird leg muscle samples were tested by histopathology for the presence of thick- and thin-walled sarcocysts. Seven percent (18/265) had only thick-walled sarcocysts, 0.8% (2/265) had only thin-walled sarcocysts and 1.9% (5/265) had both. The other half of these leg muscles when tested by PCR-RFLP of RAPD-derived DNA and SSU rRNA PCR showed a good correlation with histopathological results and the two molecular typing methods concurred; 9.8% (26/265) of cowbirds had sarcocysts in muscle, 7.9% (21/265) had S. falcatula sarcocysts, 1.1% (3/265) had S. neurona sarcocysts, and 0.8% (2/265) had both. These results show that some cowbirds have S. neurona as well as S. falcatula in their leg muscles and can act as intermediate hosts for both parasites.
- Published
- 2008
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42. Candidate mechanisms controlling the electrical characteristics of silica/XLPE nanodielectrics
- Author
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Mihir Roy, Linda S. Schadler, R.K. MacCrone, and J. Keith Nelson
- Subjects
chemistry.chemical_classification ,Materials science ,Nanocomposite ,Dielectric strength ,Mechanical Engineering ,Dielectric ,Polymer ,Polyethylene ,Dielectric spectroscopy ,chemistry.chemical_compound ,Low-density polyethylene ,chemistry ,Mechanics of Materials ,General Materials Science ,Composite material ,Nanoscopic scale - Abstract
The incorporation of silica nanoparticles into polyethylene has been shown to increase the breakdown strength significantly compared to composites with micron scale fillers. Additionally, the voltage endurance of the nanocomposites is two orders of magnitude higher than that of the base polymer. The most significant difference between micron-scale and nano-scale fillers is the large interfacial area in nanocomposites. Because the interfacial region (interaction zone) is likely to be pivotal in controlling properties, this paper compares the behavior of nanoscale silica/cross-linked low density polyethylene nanocomposites with several silica surface treatments. In addition to breakdown strength and voltage endurance, dielectric spectroscopy, absorption current measurements, and thermally stimulated current determinations (TSC) were performed to elucidate the role of the interface. It was found that a reduction in the mobility in nanocomposites as well as a change in the defect size may be key to explaining the improvement in the properties.
- Published
- 2007
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43. Bimodal brush functionalized TiO2/silicone nanocomposites with improved dielectric properties
- Author
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Yanhui Huang, Brian C. Benicewicz, Linda S. Schadler, J. Keith Nelson, Michael Bell, and Timothy M. Krentz
- Subjects
chemistry.chemical_classification ,chemistry.chemical_compound ,Anthracene ,Silicone ,Nanocomposite ,Materials science ,chemistry ,Chemical engineering ,Nanoparticle ,Dielectric ,Polymer ,Silicone rubber ,Space charge - Abstract
Bimodal ligand engineering was applied in TiO 2 /silicone nanocomposites to independently control the nanoparticle dispersion and interface properties. The introduction of well-dispersed anthracene grafted TiO 2 nanoparticles improved the AC breakdown strength and retarded the space charge accumulation in silicone rubber. A candidate mechanism of charge trapping and impact ionization of TiO 2 and anthracene is proposed to explain the improvements.
- Published
- 2015
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44. Free volume in nanodielectrics
- Author
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Brian C. Benicewicz, Michael Bell, J. Keith Nelson, Timothy M. Krentz, Jerzy Dryzek, Linda S. Schadler, and Yanhui Huang
- Subjects
Work (thermodynamics) ,Nanocomposite ,Materials science ,Dielectric strength ,Volume (thermodynamics) ,visual_art ,visual_art.visual_art_medium ,Electrical breakdown ,Particle ,Epoxy ,Composite material ,Glass transition - Abstract
It is now well established that the incorporation of nanoparticulates into a polymer matrix to form a nanodielectric can bring about useful improvements in electric strength provided that the processing results in acceptable particle dispersion. One of the theories of electrical breakdown in polymers seeks to associate breakdown with the polymer free volume, and the well-documented substantial changes in electric strength occurring at glass transition provide some credence to that theory. While it is clear that interactions at the large internal interfacial area in a nanodielectric facilitate the augmentation of dielectric strength, the exact mechanism has not been clarified. Very early work using a compression methodology to estimate free volume in an epoxy nanodielectric indicated that the particles did little to affect free volume. However, this contribution seeks to use positron annihilation lifetime spectroscopy to estimate free volume in an epoxy and several of its SiO2-based nanocomposites to estimate the changes in free volume brought about both through the incorporation of nanoparticulates and also through their functionalization. This study broadly confirms the earlier work and provides good evidence that the free volume is little affected, and thus is not an explanation for the observed change in dielectric strength.
- Published
- 2015
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45. The development and validation of methods for evaluating the immune system in preweaning piglets
- Author
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Brinda Mahadevan, Mark Cameron, Brandon M. Zeigler, Keith Nelson, Myra L. Weiner, Bjorn A. Thorsrud, and Kristi Bailey
- Subjects
Male ,Michigan ,Sus scrofa ,Positive control ,Immunotoxicology ,Toxicology ,Research model ,Immunophenotyping ,Immune system ,Toxicity Tests ,Medicine ,Animals ,Immunity, Mucosal ,Crosses, Genetic ,Innate immune system ,Mucous Membrane ,business.industry ,Protein Stability ,Models, Immunological ,Reproducibility of Results ,General Medicine ,Flow Cytometry ,Immunohistochemistry ,Sample stability ,Immunity, Innate ,Gastrointestinal Tract ,Animals, Newborn ,Immunology ,Cytokines ,Gastrointestinal tissue ,Female ,business ,Biomarkers ,Food Science - Abstract
The preweaning piglet has been found to be a valuable research model for testing ingredients used in infant formula. As part of the safety assessment, the neonates' immune system is an important component that has to be evaluated. In this study three concurrent strategies were developed to assess immune system status. The methods included (1) immunophenotying to assess circulating innate immune cell populations, (2) monitoring of circulating cytokines, particularly in response to a positive control agent, and (3) monitoring of localized gastrointestinal tissue cytokines using immunohistochemistry (IHC), particularly in response to a positive control agent. All assays were validated using white papers and regulatory guidance within a GLP environment. To validate the assays precision, accuracy and sample stability were evaluated as needed using a fit for purpose approach. In addition animals were treated with proinflammtory substances to detect a positive versus negative signal. In conclusion, these three methods were confirmed to be robust assays to evaluate the immune system and GIT-specific immune responses of preweaning piglets.
- Published
- 2015
46. ANTIBODIES TO CANINE AND FELINE VIRUSES IN SPOTTED HYENAS (CROCUTA CROCUTA) IN THE MASAI MARA NATIONAL RESERVE
- Author
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Edward J. Dubovi, Russell C. Van Horn, Linda Munson, Jonna A.K. Mazet, Anne L. Engh, Tara M. Harrison, Keith Nelson, and Kay E. Holekamp
- Subjects
Male ,Feline coronavirus ,Feline immunodeficiency virus ,Parvovirus, Canine ,viruses ,Carnivora ,Animals, Wild ,Feline panleukopenia ,Immunodeficiency Virus, Feline ,Biology ,Antibodies, Viral ,Crocuta crocuta ,medicine.disease_cause ,Dogs ,Sex Factors ,Risk Factors ,Seroepidemiologic Studies ,biology.animal ,medicine ,Animals ,Varicellovirus ,Coronavirus, Feline ,Distemper Virus, Canine ,Ecology, Evolution, Behavior and Systematics ,Disease Reservoirs ,Feline calicivirus ,Ecology ,Canine distemper ,Age Factors ,Canine parvovirus ,virus diseases ,biology.organism_classification ,medicine.disease ,Virology ,Hyena ,Virus Diseases ,Africa ,Cats ,Female ,Feline Panleukopenia Virus ,Calicivirus, Feline - Abstract
Spotted hyenas (Crocuta crocuta) are abundant predators in the Serengeti ecosystem and interact with other species of wild carnivores and domestic animals in ways that could encourage disease transmission. Hyenas also have a unique hierarchical social system that might affect the flow of pathogens. Antibodies to canine distemper virus (CDV), feline immunodeficiency virus (FIV), feline panleukopenia virus/canine parvovirus (FPLV/CPV), feline coronavirus/ feline infectious peritonitis virus (FECV/IPV), feline calicivirus (FCV), and feline herpesvirus 1 (FHV1) have been detected in other Serengeti predators, indicating that these viruses are present in the ecosystem. The purpose of this study was to determine whether spotted hyenas also had been infected with these viruses and to assess risk factors for infection. Serum samples were collected between 1993 and 2001 from 119 animals in a single clan for which behavioral data on social structure were available and from 121 hyenas ill several other clans. All animals resided in the Masai Mara National Reserve. Antibodies to CDV, FIV, FPLV/CPV, FECV/FIPV, FCV, and FHV1 were present in 47%, 3.5%, 81%, 36%, 72%, and 0.5% of study hyenas, respectively. Antibody prevalence was greater in adults for FIV and FECV/FIPV, and being a female of high social rank was a risk factor for FIV. Hyenas near human habitation appeared to be at lower risk to have CDV, FIV, and FECV/FIPV antibodies, whereas being near human habitation increased the risk for FPLV/CPV antibodies. Canine (distemper virus and FECV/FIPV antibody prevalence varied considerably over time, whereas FIV, FPLV/CPV, and FCV had a stable, apparently endemic temporal pattern. These results indicate that hyenas might play a role in the ecology of these viruses in the Serengeti ecosystem. The effect of these viruses on hyena health should be further investigated. The lower prevalence of CDV antibody-positive hyenas near human habitation suggests that reservoirs for CDV other than domestic dogs are present in the Serengeti ecosystem.
- Published
- 2004
- Full Text
- View/download PDF
47. Coprologic Survey of Parasites of Spotted Hyenas (Crocuta crocuta) in the Masai Mara National Reserve, Kenya
- Author
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Keith Nelson, Karen K. Hubbard, Kay E. Holekamp, Robert Peebles, Alexander D. Hernandez, and Anne L. Engh
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Veterinary medicine ,Ecology ,biology ,Trichuris ,Carnivora ,Mesocestoides ,biology.organism_classification ,Crocuta crocuta ,Kenya ,Isospora ,Feces ,Ancylostoma ,parasitic diseases ,Prevalence ,Taeniidae ,Animals ,Spirometra ,Helminthiasis, Animal ,Intestinal Diseases, Parasitic ,Protozoan Infections, Animal ,Ecology, Evolution, Behavior and Systematics ,Spirurida - Abstract
Seventy fecal samples from spotted hyenas (Crocuta crocuta) in the Masai Mara National Reserve, Kenya were examined for parasite eggs and oocysts using sugar flotation. A total of nine parasite genera were identified, and all samples were positive for at least one parasite species. Most individuals were infected with Ancylostoma sp. and Spirometra sp., and these species had the highest median intensity of infection. Other parasites identified include Isospora sp., Taeniidae, Spirurida, Toxocara sp., Mesocestoides sp., Dipylidium sp., and Trichuris sp.
- Published
- 2003
- Full Text
- View/download PDF
48. Suppression of space charge in crosslinked polyethylene filled with poly(stearyl methacrylate)-grafted SiO2 nanoparticles
- Author
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Ling Zhang, Yuanxiang Zhou, Linda S. Schadler, J. Keith Nelson, Mohammad M. Khani, Timothy M. Krentz, Yanhui Huang, and Brian C. Benicewicz
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010302 applied physics ,chemistry.chemical_classification ,Range (particle radiation) ,Materials science ,Physics and Astronomy (miscellaneous) ,02 engineering and technology ,Polymer ,Polyethylene ,021001 nanoscience & nanotechnology ,Methacrylate ,Grafting ,01 natural sciences ,Space charge ,chemistry.chemical_compound ,Colloid ,chemistry ,Chemical engineering ,0103 physical sciences ,0210 nano-technology ,Dispersion (chemistry) - Abstract
Incorporating inorganic nanoparticles (NPs) into polymer matrices provides a promising solution for suppressing space charge effects that can lead to premature failure of electrical insulation used in high voltage direct current engineering. However, realizing homogeneous NP dispersion is a great challenge especially in high-molecular-weight polymers. Here, we address this issue in crosslinked polyethylene by grafting matrix-compatible polymer brushes onto spherical colloidal SiO2 NPs (10–15 nm diameter) to obtain a uniform NP dispersion, thus achieving enhanced space charge suppression, improved DC breakdown strength, and restricted internal field distortion (≤10.6%) over a wide range of external DC fields from −30 kV/mm to −100 kV/mm at room temperature. The NP dispersion state is the key to ensuring an optimized distribution of deep trapping sites. A well-dispersed system provides sufficient charge trapping sites and shows better performance compared to ones with large aggregates. This surface ligand s...
- Published
- 2017
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49. Prediction of interface dielectric relaxations in bimodal brush functionalized epoxy nanodielectrics by finite element analysis method
- Author
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L. Catherine Brinson, Curt M. Breneman, He Zhao, Linda S. Schadler, Yang Li, Brian C. Benicewicz, Timothy M. Krentz, Yanhui Huang, J. Keith Nelson, Ke Wu, and Michael Bell
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Materials science ,Interface (Java) ,law ,visual_art ,visual_art.visual_art_medium ,Brush ,Dielectric ,Epoxy ,Composite material ,Finite element method ,law.invention - Published
- 2014
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50. Enhanced charge trapping in bimodal brush functionalized silica-epoxy nanocomposite dielectrics
- Author
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Michael Bell, J. Keith Nelson, Yanhui Huang, Su Zhao, Henrik Hillborg, Linda S. Schadler, Brian C. Benicewicz, and Timothy M. Krentz
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Nanocomposite ,Materials science ,Chemical engineering ,law ,visual_art ,visual_art.visual_art_medium ,Brush ,Charge (physics) ,Dielectric ,Epoxy ,Trapping ,law.invention - Published
- 2014
- Full Text
- View/download PDF
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