65 results on '"Chen, Karen"'
Search Results
2. ACR Appropriateness Criteria® Acute Elbow and Forearm Pain.
- Author
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Chen, Karen C., Ha, Alice S., Bartolotta, Roger J., Avery, Ryan, Bucknor, Matthew D., Flug, Jonathan, Geannette, Christian S., Grushky, Alexander David, Hose, Michal, Laur, Olga, Raizman, Noah M., and Chang, Eric Y.
- Abstract
Acute elbow pain can be the result of traumatic and atraumatic processes. Pathologic processes include osseous, ligamentous, and tendinous etiologies. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Poly(ethylene glycol)-block-poly(d,l-lactic acid) micelles containing oligo(lactic acid)8-paclitaxel prodrug: In Vivo conversion and antitumor efficacy
- Author
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Tam, Yu Tong, Shin, Dae Hwan, Chen, Karen E., and Kwon, Glen S.
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- 2019
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4. Chronic post-stroke fatigue: It may no longer be about the stroke itself
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Chen, Karen and Marsh, Elisabeth B.
- Published
- 2018
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5. Pre-stroke employment results in better patient-reported outcomes after minor stroke: Short title: Functional outcomes after minor stroke
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Marsh, Elisabeth B., Lawrence, Erin, Hillis, Argye E., Chen, Karen, Gottesman, Rebecca F., and Llinas, Rafael H.
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- 2018
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6. X-ray nanotomography analysis of the microstructural evolution of LiMn2O4 electrodes
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Liu, Zhao, Han, Kai, Chen-Wiegart, Yu-chen Karen, Wang, Jiajun, Kung, Harold H., Wang, Jun, Barnett, Scott A., and Faber, Katherine T.
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- 2017
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7. Combined electrochemical and X-ray tomography study of the high temperature evolution of Nickel – Yttria Stabilized Zirconia solid oxide fuel cell anodes
- Author
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Kennouche, David, Chen-Wiegart, Yu-chen Karen, Riscoe, Casey, Wang, Jun, and Barnett, Scott A.
- Published
- 2016
- Full Text
- View/download PDF
8. Tortuosity characterization of 3D microstructure at nano-scale for energy storage and conversion materials
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Chen-Wiegart, Yu-chen Karen, DeMike, Ross, Erdonmez, Can, Thornton, Katsuyo, Barnett, Scott A., and Wang, Jun
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- 2014
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9. Three-dimensional reconstruction and analysis of an entire solid oxide fuel cell by full-field transmission X-ray microscopy
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Cronin, J. Scott, Chen-Wiegart, Yu-chen Karen, Wang, Jun, and Barnett, Scott A.
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- 2013
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10. Developing standard procedures for pre-clinical efficacy studies in mouse models of spinal muscular atrophy: Report of the expert workshop “Pre-clinical testing for SMA”, Zürich, March 29–30th 2010
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Willmann, Raffaella, Dubach, Judith, and Chen, Karen
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- 2011
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11. ACR Appropriateness Criteria® Chronic Elbow Pain.
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Thomas, Jonelle M., Chang, Eric Y., Ha, Alice S., Bartolotta, Roger J., Bucknor, Matthew D., Caracciolo, Jamie T., Chen, Karen C., Flug, Jonathan, Kumaravel, Manickam, Raizman, Noah M., Ross, Andrew B., Silvis, Matthew L., Surasi, Devaki Shilpa, Beaman, Francesca D., and Expert Panel on Musculoskeletal Imaging
- Abstract
Chronic elbow pain can be osseous, soft tissue, cartilaginous, and nerve related in etiology. Imaging plays an important role in differentiating between these causes of chronic elbow pain. This document provides recommendations for imaging of chronic elbow pain in adult patients. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
12. ACR Appropriateness Criteria® Osteonecrosis: 2022 Update.
- Author
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Ha, Alice S., Chang, Eric Y., Bartolotta, Roger J., Bucknor, Matthew D., Chen, Karen C., Ellis, Henry B., Flug, Jonathan, Leschied, Jessica R., Ross, Andrew B., Sharma, Akash, Thomas, Jonelle M., Beaman, Francesca D., Expert Panel on Musculoskeletal Imaging, and Ellis, Henry B Jr
- Abstract
Osteonecrosis is defined as bone death due to inadequate vascular supply. It is sometimes also called "avascular necrosis" and "aseptic necrosis" when involving epiphysis, or "bone infarct" when involving metadiaphysis. Common sites include femoral head, humeral head, tibial metadiaphysis, femoral metadiaphysis, scaphoid, lunate, and talus. Osteonecrosis is thought to be a common condition most commonly affecting adults in third to fifth decades of life. Risk factors for osteonecrosis are numerous and include trauma, corticosteroid therapy, alcohol use, HIV, lymphoma/leukemia, blood dyscrasias, chemotherapy, radiation therapy, Gaucher disease, and Caisson disease. Epiphyseal osteonecrosis can lead to subchondral fracture and secondary osteoarthritis whereas metadiaphyseal cases do not, likely explaining their lack of long-term sequelae. Early diagnosis of osteonecrosis is important: 1) to exclude other causes of patient's pain and 2) to allow for possible early surgical prevention to prevent articular collapse and need for joint replacements. Imaging is also important for preoperative planning. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer-reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances in which peer-reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
13. Mice lacking nerve growth factor display perinatal loss of sensory and sympathetic neurons yet develop basal forebrain cholinergic neurons
- Author
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Crowley, Craig, Spencer, Susan D., Nishimura, Merry C., Chen, Karen S., Pitts-Meek, Sharon, Armanini, Mark P., Ling, Lanway H., McMahon, Stephen B., Shelton, David L., Levinson, Arthur, and Phillips, Heidi S.
- Subjects
Nerves, Peripheral -- Research ,Genetic recombination -- Research ,Nerve growth factor -- Physiological aspects ,Biological sciences - Abstract
Nerve growth factor (NGF) gene disruption induced by homologous recombination in embryonic stem (ES) cells is used to evaluate the influence of NGF deletion on neurons of the central and the peripheral nervous system. Abundant cell loss in the sensory and sympathetic ganglia of animals homozygous for NGF disruption establishes the essentiality of NGF for these neurons and the lack of compensatory action by other neurotrophins.
- Published
- 1994
14. ACR Appropriateness Criteria® Acute Trauma to the Ankle.
- Author
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Smith, Stacy E., Chang, Eric Y., Ha, Alice S., Bartolotta, Roger J., Bucknor, Matthew, Chandra, Tushar, Chen, Karen C., Gorbachova, Tetyana, Khurana, Bharti, Klitzke, Alan K., Lee, Kenneth S., Mooar, Pekka A., Ross, Andrew B., Shih, Richard D., Singer, Adam D., Taljanovic, Mihra S., Thomas, Jonelle M., Tynus, Katherine M., and Kransdorf, Mark J.
- Abstract
Acute injuries to the ankle are frequently encountered in the setting of the emergency room, sport, and general practice. This ACR Appropriateness Criteria defines best practices for imaging evaluation for several variants of patients presenting with acute ankle trauma. The variants include scenarios when Ottawa Rules can be evaluated, when there are exclusionary criteria, when Ottawa Rules cannot be evaluated, as well as specific injuries. Clinical scenarios are followed by the imaging choices and their appropriateness with an accompanying narrative explanation to help physicians to order the most appropriate imaging test. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
15. ACR Appropriateness Criteria® Acute Trauma to the Ankle.
- Author
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Expert Panel on Musculoskeletal Imaging, Smith, Stacy E, Chang, Eric Y, Ha, Alice S, Bartolotta, Roger J, Bucknor, Matthew, Chandra, Tushar, Chen, Karen C, Gorbachova, Tetyana, Khurana, Bharti, Klitzke, Alan K, Lee, Kenneth S, Mooar, Pekka A, Ross, Andrew B, Shih, Richard D, Singer, Adam D, Taljanovic, Mihra S, Thomas, Jonelle M, Tynus, Katherine M, and Kransdorf, Mark J
- Abstract
Acute injuries to the ankle are frequently encountered in the setting of the emergency room, sport, and general practice. This ACR Appropriateness Criteria defines best practices for imaging evaluation for several variants of patients presenting with acute ankle trauma. The variants include scenarios when Ottawa Rules can be evaluated, when there are exclusionary criteria, when Ottawa Rules cannot be evaluated, as well as specific injuries. Clinical scenarios are followed by the imaging choices and their appropriateness with an accompanying narrative explanation to help physicians to order the most appropriate imaging test. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
16. ACR Appropriateness Criteria® Acute Trauma to the Knee.
- Author
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Taljanovic, Mihra S., Chang, Eric Y., Ha, Alice S., Bartolotta, Roger J., Bucknor, Matthew, Chen, Karen C., Gorbachova, Tetyana, Khurana, Bharti, Klitzke, Alan K., Lee, Kenneth S., Mooar, Pekka A., Nguyen, Jie C., Ross, Andrew B., Shih, Richard D., Singer, Adam D., Smith, Stacy E., Thomas, Jonelle M., Yost, William J., and Kransdorf, Mark J.
- Abstract
Acute trauma to the knee is a common presentation seen in the emergency department. After a routine clinical examination, imaging is frequently performed to facilitate the diagnosis and almost always starts with radiographs. If clinically indicated, advanced cross-sectional imaging may then be performed for further evaluation. CT is often performed for preoperative planning of the complex tibial plateau and distal femur fractures. Currently, MRI is the study of choice for evaluation of bone marrow, internal derangements, and other soft-tissue injuries about the knee joint. In patients with knee dislocations, MR angiography may be performed simultaneously with MRI for evaluation of internal derangements and vascular injuries with less morbidity compared to conventional angiography. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
17. ACR Appropriateness Criteria® Acute Trauma to the Knee.
- Author
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Expert Panel on Musculoskeletal Imaging, Taljanovic, Mihra S, Chang, Eric Y, Ha, Alice S, Bartolotta, Roger J, Bucknor, Matthew, Chen, Karen C, Gorbachova, Tetyana, Khurana, Bharti, Klitzke, Alan K, Lee, Kenneth S, Mooar, Pekka A, Nguyen, Jie C, Ross, Andrew B, Shih, Richard D, Singer, Adam D, Smith, Stacy E, Thomas, Jonelle M, Yost, William J, and Kransdorf, Mark J
- Abstract
Acute trauma to the knee is a common presentation seen in the emergency department. After a routine clinical examination, imaging is frequently performed to facilitate the diagnosis and almost always starts with radiographs. If clinically indicated, advanced cross-sectional imaging may then be performed for further evaluation. CT is often performed for preoperative planning of the complex tibial plateau and distal femur fractures. Currently, MRI is the study of choice for evaluation of bone marrow, internal derangements, and other soft-tissue injuries about the knee joint. In patients with knee dislocations, MR angiography may be performed simultaneously with MRI for evaluation of internal derangements and vascular injuries with less morbidity compared to conventional angiography. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
18. 3D analysis of a LiCoO2–Li(Ni1/3Mn1/3Co1/3)O2 Li-ion battery positive electrode using x-ray nano-tomography
- Author
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Chen-Wiegart, Yu-chen Karen, Liu, Zhao, Faber, Katherine T., Barnett, Scott A., and Wang, Jun
- Published
- 2013
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19. Imaging of 3D morphological evolution of nanoporous silicon anode in lithium ion battery by X-ray nano-tomography.
- Author
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Zhao, Chonghang, Wada, Takeshi, De Andrade, Vincent, Gürsoy, Doğa, Kato, Hidemi, and Chen-Wiegart, Yu-chen Karen
- Abstract
Abstract Nanostructured silicon with its high theoretical capacity and ability to accommodate volume expansion has attracted great attention as a promising anode material for Lithium ion (Li-ion) batteries. Liquid metal dealloying method, is a novel method to create nanoporous silicon (np-Si). The assembled Li-ion batteries based on such np-Si anode can be cycled beyond 1500 cycles, in 1000 mA h/g constant capacity cycling mode with consistent performance; however, it suffers from degradation after ~ 460 cycles, while being cycled under 2000 mA h/g. To reveal the failure mechanism and differences in the morphological evolution in different capacity cycling modes in the np-Si anode, we conducted synchrotron X-ray nano-tomography studies. The three dimensional (3D) morphological evolution was visualized and quantified as a function of the number of cycles and cycling capacities. By comparing the 3D morphology under each cycling condition and correlating these 3D morphological changes with cycling-life performance, we elucidate the failure mechanism of the np-Si electrodes resulting from a mesoscopic to macroscopic deformation, involving volume expansion and gradual delamination. In particular, the shorter cycling life in higher-capacity cycling mode stems from particle agglomeration. Overall, while the nanoporous structure can accommodate the volume expansion locally, these mesoscopic and macroscopic deformations ultimately result in heterogeneous stress distribution with faster delamination. The work thus sheds the light on the importance to consider the structural evolution at the mesoscopic and macroscopic scales, while designing nano-structured energy storage materials for enhanced performances, particularly for long cycling-life durability. Graphical abstract fx1 Highlights • 3D morphology study of nanoporous Si (np-Si) for Li-ion batteries (LIBs). • Np-Si agglomeration and delamination leads to fast failure in high capacity cycled LIBs. • Designing nano and macroscopic structure for long cycling life LIBs. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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20. Estrogens and female liver health.
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Chen, Karen L. and Madak-Erdogan, Zeynep
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PHYSIOLOGICAL effects of estrogen , *LIVER physiology , *METABOLIC syndrome , *INSULIN resistance , *METABOLIC disorders , *DISEASE risk factors - Abstract
Due to declining estrogen levels during menopause, NAFLD prevalence is higher in postmenopausal women compared to in premenopausal women or in men. Postmenopausal women are more susceptible to weight gain, fat redistribution and dyslipidemia, all major hallmarks of metabolic syndrome associated with increased NAFLD risk. Gut microbiota plays important roles in development of gastrointestinal tract, metabolism and immunity. Host-microbe interactions allows regulation of a wide range of pathways that affect healthy and diseased physiology. Recent advances in – omics technologies, such as microbiome, transcriptome and metabolome analysis, provided evidence that estrogens and intestinal microbiota (IM) can collectively influence obesity, inflammatory disease, diabetes, and cancers. By understanding underlying mechanisms of estrogens and microbiota crosstalk, we might design dietary and pharmacological interventions to alleviate the metabolic syndrome and NAFLD. [ABSTRACT FROM AUTHOR]
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- 2018
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21. 3D morphological evolution of Li-ion battery negative electrode LiVO2 during oxidation using X-ray nano-tomography
- Author
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Chen-Wiegart, Yu-chen Karen, Shearing, Paul, Yuan, Qingxi, Tkachuk, Andrei, and Wang, Jun
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- 2012
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22. Selective aortic balloon occlusion in placenta accreta spectrum: retrospective review of utilization and outcomes.
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Fang, Mary, Lombaard, Hendrick, Belfort, Michael A., Shamshirsaz, Amir A., Chau, Alex, Chen, Karen, Kukreja, Kamlesh, Pezeshkmehr, Amir, and Fox, Karin A.
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PLACENTA accreta ,BALLOON occlusion ,AORTA ,RETROSPECTIVE studies - Published
- 2023
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23. Estrogen and Microbiota Crosstalk: Should We Pay Attention?
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Chen, Karen L. and Madak-Erdogan, Zeynep
- Subjects
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GUT microbiome , *ESTROGEN , *STEROID hormones , *OBESITY , *DIABETES - Abstract
Recent advances have suggested that steroid hormones such as estrogens, and gut microbiota might synergize to influence obesity, diabetes, and cancer. We discuss recent knowledge of the interactions between estrogens and gut microbiota, and new insights that might offer new approaches to influence this crosstalk and improve metabolic outcomes. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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24. Finite element analysis of mechanical stability of coarsened nanoporous gold.
- Author
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Cho, Hoon-Hwe, Chen-Wiegart, Yu-chen Karen, and Dunand, David C.
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GOLD nanoparticles , *OSTWALD ripening , *NANOPOROUS materials , *CHEMICAL stability , *FINITE element method , *VOLUMETRIC analysis - Abstract
The mechanical stability of nanoporous gold (np-Au) at various stages of thermal coarsening is studied via finite element analysis under volumetric compression using np-Au architectures imaged via X-ray nano-tomography. As the np-Au is coarsened thermally over ligament sizes ranging from 185 to 465 nm, the pore volume fraction is determinant for the mechanical stability of the coarsened np-Au, unlike the curvature and surface orientation of the ligaments. The computed Young's modulus and yield strength of the structures are compared with the Gibson–Ashby model. The geometry of the structures determines the locations where stress concentrations occur at the onset of yielding. [ABSTRACT FROM AUTHOR]
- Published
- 2016
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25. Observing the microstructural evolution of Ni-Yttria-stabilized zirconia solid oxide fuel cell anodes.
- Author
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Kennouche, David, Chen-Wiegart, Yu-chen Karen, Yakal-Kremski, Kyle J., Wang, Jun, Gibbs, John W., Voorhees, Peter W., and Barnett, Scott A.
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NICKEL compounds , *YTTRIA stabilized zirconium oxide , *METAL microstructure , *SOLID oxide fuel cell electrodes , *HIGH temperature metallurgy , *CHEMICAL decomposition - Abstract
This report describes a transmission X-ray microscopy observation of the high-temperature microstructural evolution of a solid oxide fuel cell Ni-Yttria-stabilized zirconia (Ni-YSZ) anode. Unlike prior studies that compared microstructural differences between different anodes, this three-dimensional measurement directly shows the changes occurring in the same region of an anode, enabling a new understanding of evolutionary processes. High-temperature ageing for 48 h at 1050 °C yielded substantial structural changes in the Ni, YSZ and pore networks, including coalescence of Ni particles, leading to a three-fold decrease in three phase boundary length. Implications for fuel cell long-term degradation are discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
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26. Evaluation of older driver head functional range of motion using portable immersive virtual reality.
- Author
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Chen, Karen B., Xu, Xu, Lin, Jia-Hua, and Radwin, Robert G.
- Subjects
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BODY movement , *RANGE of motion of joints , *VIRTUAL reality , *DISEASES in older people , *SELF-evaluation , *CROSS-sectional method - Abstract
Background The number of drivers over 65 years of age continues to increase. Although neck rotation range has been identified as a factor associated with self-reported crash history in older drivers, it was not consistently reported as indicators of older driver performance or crashes across previous studies. It is likely that drivers use neck and trunk rotation when driving, and therefore the functional range of motion (ROM) (i.e. overall rotation used during a task) of older drivers should be further examined. Objective Evaluate older driver performance in an immersive virtual reality, simulated, dynamic driving blind spot target detection task. Methods A cross-sectional laboratory study recruited twenty-six licensed drivers (14 young between 18 and 35 years, and 12 older between 65 to 75 years) from the local community. Participants were asked to detect targets by performing blind spot check movements while neck and trunk rotation was tracked. Functional ROM, target detection success, and time to detection were analyzed. Results In addition to neck rotation, older and younger drivers on average rotated their trunks 9.96°and 18.04°, respectively. The younger drivers generally demonstrated 15.6° greater functional ROM ( p < .001), were nearly twice as successful in target detection due to target location ( p = .008), and had 0.46 s less target detection time ( p = .016) than the older drivers. Conclusion Assessing older driver functional ROM may provide more comprehensive assessment of driving ability than neck ROM. Target detection success and time to detection may also be part of the aging process as these measures differed between driver groups. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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27. The accuracy of the Oculus Rift virtual reality head-mounted display during cervical spine mobility measurement.
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Xu Xu, Chen, Karen B., Jia-Hua Lin, and Radwin, Robert G.
- Subjects
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VIRTUAL reality , *CERVICAL vertebrae , *BODY movement , *BIOMECHANICS , *HUMAN kinematics - Abstract
An inertial sensor-embedded virtual reality (VR) head-mounted display, the Oculus Rift (the Rift), monitors head movement so the content displayed can be updated accordingly. While the Rift may have potential use in cervical spine biomechanics studies, its accuracy in terms of cervical spine mobility measurement has not yet been validated. In the current study, a VR environment was designed to guide participants to perform prescribed neck movements. The cervical spine kinematics was measured by both the Rift and a reference motion tracking system. Comparison of the kinematics data between the Rift and the tracking system indicated that the Rift can provide good estimates on full range of motion (from one side to the other side) during the performed task. Because of inertial sensor drifting, the unilateral range of motion (from one side to neutral posture) derived from the Rift is more erroneous. The root-mean-square errors over a 1-min task were within 10° for each rotation axis. The error analysis further indicated that the inertial sensor drifted approximately 6° at the beginning of a trial during the initialization. This needs to be addressed when using the Rift in order to more accurately measure cervical spine kinematics. It is suggested that the front cover of the Rift should be aligned against a vertical plane during its initialization. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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28. Antiviral activity of lanatoside C against dengue virus infection.
- Author
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Cheung, Yan Yi, Chen, Karen Caiyun, Chen, Huixin, Seng, Eng Khuan, and Chu, Justin Jang Hann
- Subjects
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DENGUE viruses , *DENGUE , *PREVENTIVE medicine , *ANTIVIRAL agents , *CARDIAC glycosides , *FLAVIVIRUSES - Abstract
Dengue infection poses a serious threat globally due to its recent rapid spread and rise in incidence. Currently, there is no approved vaccine or effective antiviral drug for dengue virus infection. In response to the urgent need for the development of an effective antiviral for dengue virus, the US Drug Collection library was screened in this study to identify compounds with anti-dengue activities. Lanatoside C, an FDA approved cardiac glycoside was identified as a candidate anti-dengue compound. Our data revealed that lanatoside C has an IC 50 of 0.19 μM for dengue virus infection in HuH-7 cells. Dose-dependent reduction in dengue viral RNA and viral proteins synthesis were also observed upon treatment with increasing concentrations of lanatoside C. Time of addition study indicated that lanatoside C inhibits the early processes of the dengue virus replication cycle. Furthermore, lanatoside C can effectively inhibit all four serotypes of dengue virus, flavivirus Kunjin, alphavirus Chikungunya and Sindbis virus as well as the human enterovirus 71. These findings suggest that lanatoside C possesses broad spectrum antiviral activity against several groups of positive-sense RNA viruses. [ABSTRACT FROM AUTHOR]
- Published
- 2014
- Full Text
- View/download PDF
29. Effect of Ag–Au composition and acid concentration on dealloying front velocity and cracking during nanoporous gold formation.
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Chen-Wiegart, Yu-chen Karen, Wang, Steve, McNulty, Ian, and Dunand, David C.
- Subjects
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MECHANICAL alloying , *SILVER-gold alloys , *ACIDS , *FRACTURE mechanics , *NANOPOROUS materials , *ENERGY storage , *METAL catalysts - Abstract
Abstract: Nanoporous gold has many potential applications in various fields, including energy storage, catalysis, sensing and actuating. Dealloying of Ag–Au alloys under free corrosion conditions is a simple method to fabricate nanoporous gold. Here, we systematically investigate the dealloying rate of Ag–xAu alloy for a range of alloy compositions (x =20–40at.%) and nitric acid concentration (7.3–14.9M) using in situ transmission X-ray microscopy. High-resolution in situ X-ray projections and ex situ tomographic reconstructions allow imaging of the dealloying front position during dealloying. The dealloying front velocity is constant with time, and depends exponentially on the alloy Ag/Au atomic ratio and the acid molar concentration. Only the leanest alloy, Ag–20 Au, shows a large macroscopic shrinkage in sample diameter (∼38%) after dealloying, which leads to crack nucleation and growth observed in real time during dealloying. Finite element modeling is used to estimate dealloying-induced stresses and strains, and sheds light on the cracks created by the diameter shrinkage. [Copyright &y& Elsevier]
- Published
- 2013
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30. 3D analysis of a LiCoO2–Li(Ni1/3Mn1/3Co1/3)O2 Li-ion battery positive electrode using x-ray nano-tomography
- Author
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Chen-Wiegart, Yu-chen Karen, Liu, Zhao, Faber, Katherine T., Barnett, Scott A., and Wang, Jun
- Subjects
- *
LITHIUM compounds , *X-rays , *TOMOGRAPHY , *MICROSCOPY , *LITHIUM-ion batteries , *TRANSITION metals , *ELECTRODES - Abstract
Abstract: A full-field high-resolution x-ray nano-tomography technique, transmission x-ray microscopy (TXM), was used to reveal the 3D morphology of the lithium ion battery composite positive electrode: LiCoO2 (LCO)–Li(Ni1/3Mn1/3Co1/3)O2 (NMC). The TXM method allowed the unambiguous chemical identification of oxide particles by tuning the x-ray energy relative to the transition-metal absorption edges. The NMC particles have a much rougher surface compared to the LCO particles. Cracks due to processing exist in both LCO and NMC particles but the NMC particles exhibit more severe cracking and also tend to have internal pores in addition to radial cracks. Further, the carbon-based phases including the binder and the conductive carbon were identified using Zernike phase contrast imaging. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
- View/download PDF
31. Touch screen performance by individuals with and without motor control disabilities
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Chen, Karen B., Savage, Anne B., Chourasia, Amrish O., Wiegmann, Douglas A., and Sesto, Mary E.
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TOUCH screens , *PEOPLE with disabilities , *ELECTRIC motors , *ASSISTIVE computer technology , *ACCESSIBLE design , *PERFORMANCE - Abstract
Abstract: Touch technology is becoming more prevalent as functionality improves and cost decreases. Therefore, it is important that this technology is accessible to users with diverse abilities. The objective of this study was to investigate the effects of button and gap size on performance by individuals with varied motor abilities. Participants with (n = 38) and without (n = 15) a motor control disability completed a digit entry task. Button size ranged from 10 to 30 mm and gap size was either 1 or 3 mm. Results indicated that as button size increased, there was a decrease in misses, errors, and time to complete tasks. Performance for the non-disabled group plateaued at button size 20 mm, with minimal, if any gains observed with larger button sizes. In comparison, the disabled group''s performance continued to improve as button size increased. Gap size did not affect user performance. These results may help to improve accessibility of touch technology. [Copyright &y& Elsevier]
- Published
- 2013
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32. In situ imaging of dealloying during nanoporous gold formation by transmission X-ray microscopy
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Chen-Wiegart, Yu-chen Karen, Wang, Steve, Lee, Wah-Keat, McNulty, Ian, Voorhees, Peter W., and Dunand, David C.
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X-ray microscopy , *IMAGING systems , *POROUS materials , *ALLOYS , *CORROSION resistant materials , *GOLD alloys , *DISSOLUTION (Chemistry) , *NITRIC acid - Abstract
Abstract: The dealloying process is directly imaged, for the first time, by using transmission X-ray microscopy for the case of an Ag–30at.% Au wire dealloyed under free corrosion in nitric acid. The propagation of a sharp dealloying front separating the alloy from nanoporous Au was observed by two-dimensional real-time in situ imaging at 30nm resolution and measured in detail in three dimensions by an ex situ nanotomography technique at fixed time intervals. The rate of the dealloying front propagation is independent of the dealloying time up to a 3μm depth, indicating that the dealloying process to this depth is dominated by interfacial effects (i.e. gold surface diffusion and/or silver dissolution) rather than long-range transport effects (i.e. diffusion of acid and corrosion product in and out of the porous layer). The constant dealloying rate corresponds to a constant silver flux and a constant current density, even though the potential might be fluctuating under free corrosion conditions and the interfacial area is shrinking as a function of time. Free corrosion in this system generates a high current density, implying it is driven by a chemical potential difference that is much higher than the critical potential. [Copyright &y& Elsevier]
- Published
- 2013
- Full Text
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33. 3D morphological evolution of Li-ion battery negative electrode LiVO2 during oxidation using X-ray nano-tomography
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Chen-Wiegart, Yu-chen Karen, Shearing, Paul, Yuan, Qingxi, Tkachuk, Andrei, and Wang, Jun
- Subjects
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LITHIUM-ion batteries , *OXIDATION , *X-rays , *ELECTRODES , *LITHIUM compounds , *ENERGY density , *THREE-dimensional imaging - Abstract
Abstract: Lithium vanadium oxide (LiVO2 1 [1] More precisely, it is “Li1+xV1−xO2 (x>0)”. But “LiVO2” is used throughout the text for brevity . ) holds the potential promise to replace graphite as an anode material in commercial Li-ion batteries as it doubles the volumetric energy density compared to graphite but can still operate at low voltage (~0.1V vs. Li/Li+). Its degradation mechanism was investigated using a synchrotron X-ray nano-tomography technique to image the LiVO2 in three dimensions (3D). In particular an oxidation effect is discussed by a direct visualization and quantification of the 3D microstructure of the LiVO2 before and after being exposed to the air, which results in the oxidation of the LiVO2. After being exposed to air, an oxidation layer with thickness ~120–240nm was observed at the interface of the LiVO2 particles and the binders/pores. While the total volume of LiVO2 remains relatively constant before and after oxidation, the particle size reduces, which is consistent with crack growth possibly due to the local exothermal oxidation reactions, accompanied by phase transition at an elevated temperature. The findings confirm the air-sensitivity of LiVO2 observed indirectly in the literature. [Copyright &y& Elsevier]
- Published
- 2012
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- View/download PDF
34. Structural evolution of nanoporous gold during thermal coarsening
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Chen-Wiegart, Yu-chen Karen, Wang, Steve, Chu, Yong S., Liu, Wenjun, McNulty, Ian, Voorhees, Peter W., and Dunand, David C.
- Subjects
- *
MOLECULAR structure , *OSTWALD ripening , *POROUS materials , *NANOSTRUCTURED materials , *THREE-dimensional imaging , *ANISOTROPY - Abstract
Abstract: The three-dimensional evolution of nanoligaments of nanoporous gold created by Ag–Au dealloying was studied during isothermal coarsening by X-ray nanotomography and microbeam Laue diffraction. The surface normal orientation, curvature and size of the gold nanoligaments were measured as a function of coarsening time (from 2 to 320min). The following observations were made at 550, 600 and 650°C. First, the distribution of orientations for the surfaces of the nanoligaments becomes more anisotropic with coarsening time, with an increasing area of the surfaces having a low surface energy, consistent with the growth of facets. Second, the curvature distribution of the nanoligaments (scaled by their size) also evolves during coarsening. The evolution of both surface orientation and scaled surface curvature indicates that coarsening does not occur in a self-similar manner, i.e. the interfacial shape distribution of the gold nanoligaments is not self-similar over time as they coarsen. This is consistent with the ligament size not being described by a classical temporal power law for coarsening systems. All three effects, and in particular the increased prevalence of surfaces with a low surface energy at long coarsening times, may affect the surface functionalities and properties of nanoporous gold in various applications, e.g. as catalysts, sensors and actuators. [Copyright &y& Elsevier]
- Published
- 2012
- Full Text
- View/download PDF
35. Interobserver accuracy of store and forward teledermatology for skin neoplasms.
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Warshaw, Erin M., Gravely, Amy A., Bohjanen, Kimberly A., Chen, Karen, Lee, Peter K., Rabinovitz, Harold S., Johr, Robert H., and Nelson, David B.
- Published
- 2010
- Full Text
- View/download PDF
36. Accuracy of teledermatology for pigmented neoplasms.
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Warshaw, Erin M., Lederle, Frank A., Grill, Joseph P., Gravely, Amy A., Bangerter, Ann K., Fortier, Lawrence A., Bohjanen, Kimberly A., Chen, Karen, Lee, Peter K., Rabinovitz, Harold S., Johr, Robert H., Kaye, Valda N., Bowers, Sacharitha, Wenner, Rachel, Askari, Sharone K., Kedrowski, Deborah A., and Nelson, David B.
- Abstract
Background: Accurate diagnosis and management of pigmented lesions is critical because of the morbidity and mortality associated with melanoma. Objective: We sought to compare accuracy of store-and-forward teledermatology for pigmented neoplasms with standard, in-person clinic dermatology. Methods: We conducted a repeated measures equivalence trial involving veterans with pigmented skin neoplasms. Each lesion was evaluated by a clinic dermatologist and a teledermatologist; both generated a primary diagnosis, up to two differential diagnoses, and a management plan. The primary outcome was aggregated diagnostic accuracy (match of any chosen diagnosis with histopathology). We also compared the severity of inappropriately managed lesions and, for teledermatology, evaluated the incremental change in accuracy when polarized light dermatoscopy or contact immersion dermatoscopy images were viewed. Results: We enrolled 542 patients with pigmented lesions, most were male (96%) and Caucasian (97%). The aggregated diagnostic accuracy rates for teledermatology (macro images, polarized light dermatoscopy, and contact immersion dermatoscopy) were not equivalent (95% confidence interval for difference within ±10%) and were inferior (95% confidence interval lower bound <10%) to clinic dermatology. In general, the addition of dermatoscopic images did not significantly change teledermatology diagnostic accuracy rates. In contrast to diagnostic accuracy, rates of appropriate management plans for teledermatology were superior and/or equivalent to clinic dermatology (all image types: all lesions, and benign lesions). However, for the subgroup of malignant lesions (n = 124), the rate of appropriate management was significantly worse for teledermatology than for clinic dermatology (all image types). Up to 7 of 36 index melanomas would have been mismanaged via teledermatology. Limitations: Nondiverse study population and relatively small number of melanomas were limitations. Conclusions: In general, the diagnostic accuracy of teledermatology was inferior whereas management was equivalent to clinic dermatology. However, for the important subgroup of malignant pigmented lesions, both diagnostic and management accuracy of teledermatology was generally inferior to clinic dermatology and up to 7 of 36 index melanomas would have been mismanaged via teledermatology. Teledermatology and teledermatoscopy should be used with caution for patients with suspected malignant pigmented lesions. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
37. Accuracy of teledermatology for nonpigmented neoplasms.
- Author
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Warshaw, Erin M., Lederle, Frank A., Grill, Joseph P., Gravely, Amy A., Bangerter, Ann K., Fortier, Lawrence A., Bohjanen, Kimberly A., Chen, Karen, Lee, Peter K., Rabinovitz, Harold S., Johr, Robert H., Kaye, Valda N., Bowers, Sacharitha, Wenner, Rachel, Askari, Sharone K., Kedrowski, Deborah A., and Nelson, David B.
- Abstract
Background: Studies of teledermatology utilizing the standard reference of histopathology are lacking. Objective: To compare accuracy of store-and-forward teledermatology for non-pigmented neoplasms with in-person dermatology. Methods: This study was a repeated-measures equivalence trial involving veterans with non-pigmented skin neoplasms. Each lesion was evaluated by an in-person dermatologist and a teledermatologist; both generated a primary diagnosis, up to two differential diagnoses, and management plan. The primary outcome was aggregated diagnostic accuracy (percent correct matches of any chosen diagnosis with histopathology). Secondary outcomes included management plan accuracy (percent correct matches with expert panel management plan). Additional analyses included evaluation of the incremental effect of using polarized light dermatoscopy in addition to standard macro images, and evaluating benign and malignant lesion subgroups separately. Results: Most of the 728 participants were male (97.8%) and Caucasian (98.9%). The aggregated diagnostic accuracy (primary outcome) of teledermatology (macro images) was not equivalent (95% confidence interval [CI] for difference within +/−10%) and was inferior (95% CI lower bound <10%) to in-person dermatology for all lesions and the subgroups of benign and malignant lesions. However, management plan accuracy was equivalent. Teledermatology aggregated diagnostic accuracy using polarized light dermatoscopy was significantly better than for macro images alone (P = .0017). The addition of polarized light dermatoscopy showed the same pattern for malignant lesions, but not for benign lesions. Most interestingly, for malignant lesions, the addition of polarized light dermatoscopy yielded equivalent aggregated diagnostic accuracy rates. Limitations: Non-diverse study population. Conclusions: Using macro images, the diagnostic accuracy of teledermatology was inferior to in-person dermatology, but accuracy of management plans was equivalent. The addition of polarized light dermatoscopy yielded significantly better aggregated diagnostic accuracy, but management plan accuracy was not significantly improved. For the important subgroup of malignant lesions, the addition of polarized light dermatoscopy yielded equivalent diagnostic accuracy between teledermatologists and clinic dermatologists. [Copyright &y& Elsevier]
- Published
- 2009
- Full Text
- View/download PDF
38. Robot-related injuries in the workplace: An analysis of OSHA Severe Injury Reports.
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Sanders, Nathan E., Şener, Elif, and Chen, Karen B.
- Subjects
- *
INDUSTRIAL robots , *INDUSTRIAL safety , *AMPUTATION , *WORK environment , *DATA analysis - Abstract
Industrial robots are increasingly commonplace, but research on prototypical accidents and injuries has been sparse, hindering evidence-based safety strategies. Using Severe Injury Reports (SIRs) from the U.S. Occupational Safety and Health Administration (OSHA), we identified 77 robot-related accidents from 2015-2022. Of these, 54 involved stationary robots, resulting in 66 injuries, mainly finger amputations and fractures to the head and torso. Mobile robots caused 23 accidents, leading to 27 injuries, mainly fractures to the legs and feet. A two-stage deductive–inductive thematic analysis was performed using text data from the final narratives in the reports to discover patterns in tasks, precipitating mechanisms, and contributing factors. Findings highlight the need for guards and collision avoidance systems that detect individual extremities. Post-contact strategies should focus on mitigating finger amputations. More structured and detailed narratives in the SIRs are needed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
39. Red-brown plaques and nodules on the dorsal surface of the hands.
- Author
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Suwattee, Pitiporn and Chen, Karen
- Published
- 2007
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40. 174 - TOR Signal Is Suppressed by Sirt5 in Different Nutrient Condition.
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Park, Jeongsoon, Chen, Karen, Park, Junbum, and Lombard, David B
- Subjects
- *
PROTEINS , *AGE , *BIOMOLECULES , *LONGEVITY , *DIET - Abstract
Sirtuin proteins regulate nutrient signaling and metabolism through modulating protein post-translational modification (PTM), and promote longevity and health-span. SIRT5 is one of mitochondrial sirtuin among the seven Sirtuin family in mammals. SIRT5 functions as desuccinylase, demalonylase, and degrutarylase. Previous work demonstrates that a calorie-restricted (CR) diet prolongs lifespan; nevertheless, the molecular mechanisms underlying this effect have not been completely elucidated. mTOR is a protein kinase that regulates cell growth and protein synthesis in response to nutrient levels. To know how sirt5 modulate nutrient sensing system, we treated sirt5 KO and littermate WT mice with Ketogenic diet and NIA certified CR diet. Flux analysis was carried out with isolated mitochondria. Whole protein from different tissues used for PTM analysis. Downstream of mTOR signal were hyper-activated in SIRT5 KO liver, heart, and muscle tissues and this signal differentially respond to varied dietary conditions. Furthermore, CR increased overall oxygen consumption rate in WT mouse liver mitochondria but decreased in SIRT5 KO, suggesting a role for SIRT5 in regulating mitochondrial energetics in response to altered diet. SIRT5 regulates diverse PTMs, which is malonyl lysine, succinyl lysine, hydroxybutyl lysine, propionyl lysine, and crotonyl lysine in a tissue-specific manner. Therefore, we suggested that SIRT5 deficiency impacts mTOR signaling in different tissues differentially depend on nutrient stress. From this finding, further question, what kind of mechanism will be a major effect to different tissues by sirt5, come out. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
41. A comparison of the psychological effects of robot motion in physical and virtual environments.
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Sanders, Nathan Edward, Xie, Ziyang, and Chen, Karen B.
- Subjects
- *
ROBOT motion , *MIXED methods research , *ERGONOMICS , *HUMAN-robot interaction , *VIRTUAL reality - Abstract
A mixed-methods approach was used to assess the fidelity of virtual environments as ergonomic assessment tools for human-robot interaction. Participants performed a visual search task in the physical environment while a nearby collaborative robot repeatedly extended its arm toward them. This scenario was reconstructed in two virtual environments with different levels of graphical detail. Measures of presence, task performance, workload, and anxiety were taken to determine the effect of robot motion in all three environments. Task performance decreased in response to robot motion in the physical environment, while workload and anxiety increased. This simple effect of motion was consistent across environments for measures of task performance and anxiety. However, people performed faster overall in virtual reality, and the effect of motion on workload was greatly reduced in virtual reality. Results in the virtual environments suggest that people were distracted by the sound of the robot, and that presence was affected by manipulations of immersion and coherence. • Response time, workload, and anxiety increased with nearby robot motion. • Response time was faster on average in VR compared to physical reality. • Workload did not increase in VR as it did in physical reality. • People were likely distracted by the sound of the robot's motors. • Presence was affected by both immersion and coherence. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
42. Immersion of virtual reality for rehabilitation - Review.
- Author
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Rose, Tyler, Nam, Chang S., and Chen, Karen B.
- Subjects
- *
VIRTUAL reality in medicine , *MEDICAL rehabilitation , *PATIENT compliance , *POSTURE , *HAPTIC devices - Abstract
Virtual reality (VR) shows promise in the application of healthcare and because it presents patients an immersive, often entertaining, approach to accomplish the goal of improvement in performance. Eighteen studies were reviewed to understand human performance and health outcomes after utilizing VR rehabilitation systems. We aimed to understand: (1) the influence of immersion in VR performance and health outcomes; (2) the relationship between enjoyment and potential patient adherence to VR rehabilitation routine; and (3) the influence of haptic feedback on performance in VR. Performance measures including postural stability, navigation task performance, and joint mobility showed varying relations to immersion. Limited data did not allow a solid conclusion between enjoyment and adherence, but patient enjoyment and willingness to participate were reported in care plans that incorporates VR. Finally, different haptic devices such as gloves and controllers provided both strengths and weakness in areas such movement velocity, movement accuracy, and path efficiency. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
43. Using the Microsoft Kinect™ to assess 3-D shoulder kinematics during computer use.
- Author
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Xu, Xu, Robertson, Michelle, Chen, Karen B., Lin, Jia-hua, and McGorry, Raymond W.
- Subjects
- *
KINECT (Motion sensor) , *HUMAN kinematics , *SHOULDER joint , *MUSCULOSKELETAL system diseases , *HEALTH of computer users , *ERGONOMICS - Abstract
Shoulder joint kinematics has been used as a representative indicator to investigate musculoskeletal symptoms among computer users for office ergonomics studies. The traditional measurement of shoulder kinematics normally requires a laboratory-based motion tracking system which limits the field studies. In the current study, a portable, low cost, and marker-less Microsoft Kinect™ sensor was examined for its feasibility on shoulder kinematics measurement during computer tasks. Eleven healthy participants performed a standardized computer task, and their shoulder kinematics data were measured by a Kinect sensor and a motion tracking system concurrently. The results indicated that placing the Kinect sensor in front of the participants would yielded a more accurate shoulder kinematics measurements then placing the Kinect sensor 15° or 30° to one side. The results also showed that the Kinect sensor had a better estimate on shoulder flexion/extension, compared with shoulder adduction/abduction and shoulder axial rotation. The RMSE of front-placed Kinect sensor on shoulder flexion/extension was less than 10° for both the right and the left shoulder. The measurement error of the front-placed Kinect sensor on the shoulder adduction/abduction was approximately 10° to 15°, and the magnitude of error is proportional to the magnitude of that joint angle. After the calibration, the RMSE on shoulder adduction/abduction were less than 10° based on an independent dataset of 5 additional participants. For shoulder axial rotation, the RMSE of front-placed Kinect sensor ranged between approximately 15° to 30°. The results of the study suggest that the Kinect sensor can provide some insight on shoulder kinematics for improving office ergonomics. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
44. Checklists in Healthcare: Operational Improvement of Standards using Safety Engineering - Project CHOISSE - A framework for evaluating the effects of checklists on surgical team culture.
- Author
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Perera, Gimantha N., Hey, Lloyd A., Chen, Karen B., Morello, Madeline J., McConnell, Brandon M., and Ivy, Julie S.
- Subjects
- *
MEDICAL care , *INDUSTRIAL safety , *DELPHI method , *SOCIOTECHNICAL systems , *HUMAN-machine systems , *PILOT projects , *LONGITUDINAL method - Abstract
The CHOISSE multi-stage framework for evaluating the effects of electronic checklist applications (e-checklists) on surgical team members' perception of their roles, performance, communication, and understanding of checklists is introduced via a pilot study. A prospective interventional cohort study design was piloted to assess the effectiveness of the framework and the sociotechnical effects of the e-checklist. A Delphi process was used to design the stages of the framework based on literature and expert consensus. The CHOISSE framework was applied to guide the implementation and evaluation of e-checklists on team culture for ten pilot teams across the US over a 24-week period. The pilot results revealed more engagement by surgeons than non-surgeons, and significant increases in surgeons' perception of communication and engagement during surgery with a small sample. Mixed methods analysis of the data and lessons learned were used to identify iterative improvements to the CHOISSE framework and to inform future studies. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
45. Dimensionality effect of conductive carbon fillers in LiNi1/3Mn1/3Co1/3O2 cathode.
- Author
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Lin, Cheng-Hung, Ju, Zhengyu, Zheng, Xiaoyin, Zhang, Xiao, Zmich, Nicole, Liu, Xiaoyang, Takeuchi, Kenneth J., Marschilok, Amy C., Takeuchi, Esther S., Ge, Mingyuan, Yu, Guihua, and Chen-Wiegart, Yu-chen Karen
- Subjects
- *
CATHODES , *ELECTRIC conductivity , *PARTICLE size distribution , *ENERGY storage , *CARBON composites , *CARBON nanotubes - Abstract
Developing advanced electrode architectures through modifying active materials, conductive fillers, binders, and electrolytes as well as processing methods has drawn significant research interest. Due to the insufficient electrical conductivity of many active materials, adding conductive carbon fillers to composite electrodes provides the necessary electrical conductivity. The dimensionality effect among different conductive fillers has a significant impact on electrochemistry, which can be associated with morphological and chemical heterogeneities of electrodes. Here, synchrotron X-ray mosaic nanotomography and X-ray spectroscopy nanoimaging provided direct three-dimensional (3D) visualization and quantification capabilities to investigate the dimensionality effects of Super P (SP) and single-walled carbon nanotube (SWCNT) fillers on the capacity retention of LiNi 1/3 Mn 1/3 Co 1/3 O 2 (NMC111). The results indicate that NMC/SWCNT electrodes, with a wrapping effect from the SWCNTs, exhibited more homogeneous particle size distributions, morphological changes, and chemical states than NMC/SP electrodes, without the wrapping effect. This work developed a framework of 3D quantification methods to study the capacity fading behavior associated with morphological and chemical heterogeneities and paved the way toward designing electrodes for high rate energy storage applications. [Display omitted] • Capacity fade due to morphological degradation in LiN 1-x-y Mn x Co y O 2 particles. • Different shapes and dimensions of fillers showing an impact on capacity retention. • Large 3D volume visualization and quantification with sub-50 nm spatial resolution. • Single-walled carbon nanotubes showing a superior morphology and chemistry. • Single-walled carbon nanotubes reducing the negative effects of cracks. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
46. Metal desorption from copper(II)/nickel(II)-spiked kaolin as a soil component using plant-derived saponin biosurfactant
- Author
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Chen, Wen-Jang, Hsiao, Lai-Chun, and Chen, Karen Kai-Yun
- Subjects
- *
SAPONINS , *KAOLIN , *BIOSURFACTANTS , *PHYSICAL & theoretical chemistry - Abstract
Abstract: This study reports experimental measurements on the washing ability of quillaja saponin biosurfactant in kaolin suspensions, which were presorbed with the binary heavy metals of Cu(II) and Ni(II). A synthetic surfactant (SDS) and chelating agent (EDTA) were also evaluated for comparison studies. The sorption capacity for Cu(II) and Ni(II) onto kaolin were measured through the variation in pH and initial metal ion concentration. Much attention has been paid to understanding the micelle-forming properties of biosurfactant solution and its interaction with metals at the clay–water interface so washing strategies can then seek to achieve the ideal capacities of saponin biosurfactant for desorbing heavy metals from kaolin clays. The desorption of Cu(II) and Ni(II) from kaolin were examined as a function of pH, saponin concentration, temperature, time and mass/volume ratio of kaolin suspension. Because the saponin successfully competes with the kaolin clay for complexing with the metal ions by the Lewis acid–base interaction induced by pH, structure size, or charge of surfactant solution, the highest desorption improvements by 2000mg/l of saponin were gained at 20g/l kaolin suspension and pH 5–8, in which a single washing at room temperature could remove ∼83% of the copper and ∼85% of the nickel from kaolin containing 0.45mg copper/g kaolin and 0.14mg nickel/g kaolin. These results were interpreted as showing the action of a three-step micellar washing mechanism on the desorption efficiencies for Cu(II) and Ni(II). It is then pointed out quillaja saponin may be applied as a useful biosurfactant for the removal of heavy metals in contaminated clays or soils. [Copyright &y& Elsevier]
- Published
- 2008
- Full Text
- View/download PDF
47. Endovascular Intervention for Refractory Pediatric Cerebral Venous Sinus Thrombosis.
- Author
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Gadgil, Nisha, Aldave, Guillermo, Whitehead, William E., Dmytriw, Adam A., Chen, Karen, Orbach, Darren, Maier, Ilko, Behme, Daniel, Fargen, Kyle M., Elijovich, Lucas, Dornbos III, David, Spiotta, Alejandro, Kan, Peter, and Dornbos, David 3rd
- Subjects
- *
ENDOVASCULAR surgery , *VENOUS thrombosis , *CRANIAL sinuses , *SINUS thrombosis , *TREATMENT effectiveness , *THROMBOLYTIC therapy - Abstract
Background: Cerebral venous sinus thrombosis (CVST) is a rare but potentially morbid disease in the pediatric population, and the optimal treatment is not fully understood. Endovascular intervention for this condition has been rarely reported.Methods: The Stroke Thrombectomy and Aneurysm Registry was queried for patients aged less than or equal to 18 years undergoing endovascular treatment for CVST in the past 10 years. Clinical charts and radiographic data were retrospectively reviewed. Modified Rankin Score (mRS) at 90 days postprocedure was determined as the primary outcome.Results: A total of seven patients across five pediatric centers ranging from 7 to 16 years of age were identified with a mean follow-up of 28 months. All had underlying conditions predisposing to CVST. Endovascular intervention was undertaken due to neurological deterioration despite systemic anticoagulation; venous infarct was evident preoperatively in six of seven patients. Mechanical venous thrombectomy was attempted in all individuals, and intrasinus thrombolytic therapy was also performed in three cases. Six patients had favorable outcome with mRS 0 or 1 at 90 days postprocedure; one remained neurologically devastated.Conclusions: Endovascular treatment by an experienced interventionalist may be safe and effective in severe cases of CVST in children failing frontline therapy. Children with radiographic or clinical progression despite anticoagulation may be considered for endovascular intervention in a timely manner. [ABSTRACT FROM AUTHOR]- Published
- 2021
- Full Text
- View/download PDF
48. Pipeline Embolization in Patients with Posterior Circulation Subarachnoid Hemorrhages: Is Takotsubo Cardiomyopathy a Limiting Factor?
- Author
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Baker, Cordell, Grandhi, Ramesh, Griessenauer, Christoph J., Dmytriw, Adam A., Kapadia, Anish, Yang, Victor X.D., Ghorbani, Mohammad, Chen, Karen, Aziz-Sultan, Mohammad A., Rinaldo, Lorenzo, Lanzino, Giuseppe, Brinjikji, Waleed, and Taussky, Philipp
- Subjects
- *
TAKOTSUBO cardiomyopathy , *SUBARACHNOID hemorrhage , *RUPTURED aneurysms , *DISSECTING aneurysms , *CEREBRAL circulation , *PLATELET aggregation inhibitors , *ANTERIOR cerebral artery - Abstract
Hemorrhagic vascular lesions in the posterior cerebral circulation such as ruptured aneurysms and dissections can be challenging to treat. Flow diversion has become an important off-label option, but few studies have analyzed the safety of these devices in this setting. Using an international, multicenter cohort, we reviewed posterior circulation subarachnoid hemorrhage (SAH) patients treated with the Pipeline Embolization Device (PED) in the acute setting and assessed the incidence of Takotsubo cardiomyopathy (TCM). Eleven neurovascular centers were queried to identify cases of posterior circulation aneurysms or dissections treated with the PED in the acute setting of SAH. Among those, 5 centers had cases that matched the inclusion criteria. The following variables were evaluated: demographics, the location and morphology of the aneurysm, the clinical presentation, the specific form of treatment, complications including the development of TCM, antiplatelet medication regimen, and follow-up time. A total of 23 patients were treated with PED after posterior circulation SAH, and 13% of these developed TCM. The lesions were the result of hemorrhagic intracranial dissection (8 patients), ruptured pseudoaneurysm (3), ruptured saccular aneurysm (7), blister aneurysm (4), and fusiform aneurysm (1). Ninety-one percent of patients had complete or near-complete aneurysm occlusion on follow-up imaging. Five patients died in the perioperative period; 16/18 survivors had a favorable outcome. We describe an unexpectedly high incidence of TCM after the placement of PEDs in patients with posterior circulation SAH in our large case series. Further studies will be needed to elucidate possible causes. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
49. Insights into the physical and chemical properties of a cement-polymer composite developed for geothermal wellbore applications.
- Author
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Rod, Kenton A., Nguyen, Manh-Thuong, Elbakhshwan, Mohamed, Gills, Simerjeet, Kutchko, Barbara, Varga, Tamas, Mckinney, Adriana M., Roosendaal, Timothy J., Childers, M. Ian, Zhao, Chonghang, Chen-Wiegart, Yu-chen Karen, Thieme, Juergen, Koech, Phillip K., Um, Wooyong, Chun, Jaehun, Rousseau, Roger, Glezakou, Vassiliki-Alexandra, and Fernandez, Carlos A.
- Subjects
- *
GEOTHERMAL ecology , *AQUIFERS , *DENSITY functional theory , *COMPOSITE materials , *BRAIDED structures - Abstract
Abstract To isolate injection and production zones from overlying formations and aquifers during geothermal operations, cement is placed in the annulus between well casing and the formation. However, wellbore cement eventually undergoes fractures due to chemical and physical stress with the resulting time and cost intensive production shutdowns and repairs. To address this difficult problem, a polymer-cement (composite) with self-healing properties was recently developed by our group. Short-term thermal stability tests demonstrated the potential of this material for its application in geothermal environments. In this work, the authors unveil some of the physical and chemical properties of the cement composite in an attempt to better understand its performance as compared to standard cement in the absence of the polymer. Among the properties studied include material's elemental distribution, mineral composition, internal microstructure, and tensile elasticity. Polymer-cement composites have relatively larger, though not interconnected, levels of void spaces compared to conventional cement. Most of these void spaces are filled with polymer. The composites also seem to have higher levels of uncured cement grains as the polymer seems to act as a retarder in the curing process. The presence of homogeneously-distributed more flexible polymer in the cement brings about 60–70% higher tensile elasticity to the composite material, as confirmed experimentally and by density-functional calculations. The improved tensile elasticity suggests that the composite materials can outperform conventional cement under mechanical stress. In addition, calculations indicate that the bonding interactions between the cement and polymer remain stable over the range of strain studied. The results suggest that this novel polymer-cement formulation could represent an important alternative to conventional cement for application in high-temperature subsurface settings. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
50. Diagnosis of Breast Diseases: Integrating the Findings of Clinical Presentation, Mammography, and Ultrasound.
- Author
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Chen, Karen C.
- Published
- 2012
- Full Text
- View/download PDF
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