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171 results on '"Cheung, C.-L."'

1. Anomalous beam transport through Gabor (plasma) lens prototype

Author

Nonnenmacher, T., Dascalu, T. S., Bingham, R., Cheung, C. L., Lau, H. T., Long, K. R., Pozimski, J., and Whyte, C.

Subjects
Physics - Accelerator Physics, Physics - Plasma Physics
Abstract

An electron plasma lens is a cost-effective, compact, strong-focusing element that can ensure efficient capture of low-energy proton and ion beams from laser-driven sources. A Gabor lens prototype was built for high electron density operation at Imperial College London. The parameters of the stable operation regime of the lens and its performance during a beam test with 1.4 MeV protons are reported here. Narrow pencil beams were imaged on a scintillator screen 67 cm downstream of the lens. The lens converted the pencil beams into rings that show position-dependent shape and intensity modulation that are dependent on the settings of the lens. Characterisation of the focusing effect suggests that the plasma column exhibited an off-axis rotation similar to the $m=1$ diocotron instability. The association of the instability with the cause of the rings was investigated using particle tracking simulations., Comment: 22 pages, 17 figures, preprint submitted to Applied Sciences

Published
2021
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2. Interactions of magnetized plasma flows in pulsed-power driven experiments

Author

Suttle, L G, Burdiak, G C, Cheung, C L, Clayson, T, Halliday, J W D, Hare, J D, Rusli, S, Russell, D, Tubman, E, Ciardi, A, Loureiro, N F, Li, J, Frank, A, and Lebedev, S V

Subjects
Physics - Plasma Physics
Abstract

A supersonic flow of magnetized plasma is produced by the application of a 1 MA-peak, 500 ns current pulse to a cylindrical arrangement of parallel wires, known as an inverse wire array. The plasma flow is produced by the JxB acceleration of the ablated wire material, and a magnetic field of several Tesla is embedded at source by the driving current. This setup has been used for a variety of experiments investigating the interactions of magnetized plasma flows. In experiments designed to investigate magnetic reconnection, the collision of counter-streaming flows, carrying oppositely directed magnetic fields, leads to the formation of a reconnection layer in which we observe ions reaching temperatures much greater than predicted by classical heating mechanisms. The breakup of this layer under the plasmoid instability is dependent on the properties of the inflowing plasma, which can be controlled by the choice of the wire array material. In other experiments, magnetized shocks were formed by placing obstacles in the path of the magnetized plasma flow. The pile-up of magnetic flux in front of a conducting obstacle produces a magnetic precursor acting on upstream electrons at the distance of the ion inertial length. This precursor subsequently develops into a steep density transition via ion-electron fluid decoupling. Obstacles which possess a strong private magnetic field affect the upstream flow over a much greater distance, providing an extended bow shock structure. In the region surrounding the obstacle the magnetic pressure holds off the flow, forming a void of plasma material, analogous to the magnetopause around planetary bodies with self-generated magnetic fields., Comment: 46th EPS conference on Plasma Physics, Milan, Italy 2019

Published
2019
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6. Asia-Pacific consensus on long-term and sequential therapy for osteoporosis.

Author

Tai, T-W, Chen, H-Y, Shih, C-A, Huang, C-F, McCloskey, E, Lee, J-K, Yeap, SS, Cheung, C-L, Charatcharoenwitthaya, N, Jaisamrarn, U, Kuptniratsaikul, V, Yang, R-S, Lin, S-Y, Taguchi, A, Mori, S, Li-Yu, J, Ang, SB, Chan, D-C, Chan, WS, Ng, H, Chen, J-F, Tu, S-T, Chuang, H-H, Chang, Y-F, Chen, F-P, Tsai, K-S, Ebeling, PR, Marin, F, Nistal Rodríguez, FJ, Shi, H, Hwang, KR, Kim, K-K, Chung, Y-S, Reid, IR, Chandran, M, Ferrari, S, Lewiecki, EM, Hew, FL, Ho-Pham, LT, Nguyen, TV, Nguyen, VH, Lekamwasam, S, Pandey, D, Bhadada, S, Chen, C-H, Hwang, J-S, Wu, C-H, Tai, T-W, Chen, H-Y, Shih, C-A, Huang, C-F, McCloskey, E, Lee, J-K, Yeap, SS, Cheung, C-L, Charatcharoenwitthaya, N, Jaisamrarn, U, Kuptniratsaikul, V, Yang, R-S, Lin, S-Y, Taguchi, A, Mori, S, Li-Yu, J, Ang, SB, Chan, D-C, Chan, WS, Ng, H, Chen, J-F, Tu, S-T, Chuang, H-H, Chang, Y-F, Chen, F-P, Tsai, K-S, Ebeling, PR, Marin, F, Nistal Rodríguez, FJ, Shi, H, Hwang, KR, Kim, K-K, Chung, Y-S, Reid, IR, Chandran, M, Ferrari, S, Lewiecki, EM, Hew, FL, Ho-Pham, LT, Nguyen, TV, Nguyen, VH, Lekamwasam, S, Pandey, D, Bhadada, S, Chen, C-H, Hwang, J-S, and Wu, C-H

Abstract

OBJECTIVES: This study aimed to present the Asia-Pacific consensus on long-term and sequential therapy for osteoporosis, offering evidence-based recommendations for the effective management of this chronic condition. The primary focus is on achieving optimal fracture prevention through a comprehensive, individualized approach. METHODS: A panel of experts convened to develop consensus statements by synthesizing the current literature and leveraging clinical expertise. The review encompassed long-term anti-osteoporosis medication goals, first-line treatments for individuals at very high fracture risk, and the strategic integration of anabolic and antiresorptive agents in sequential therapy approaches. RESULTS: The panelists reached a consensus on 12 statements. Key recommendations included advocating for anabolic agents as the first-line treatment for individuals at very high fracture risk and transitioning to antiresorptive agents following the completion of anabolic therapy. Anabolic therapy remains an option for individuals experiencing new fractures or persistent high fracture risk despite antiresorptive treatment. In cases of inadequate response, the consensus recommended considering a switch to more potent medications. The consensus also addressed the management of medication-related complications, proposing alternatives instead of discontinuation of treatment. CONCLUSIONS: This consensus provides a comprehensive, cost-effective strategy for fracture prevention with an emphasis on shared decision-making and the incorporation of country-specific case management systems, such as fracture liaison services. It serves as a valuable guide for healthcare professionals in the Asia-Pacific region, contributing to the ongoing evolution of osteoporosis management.

Published
2024

7. Deep optical imaging of AGB circumstellar envelopes

Author

Mauron, N., Huggins, P. J., and Cheung, C. -L.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We report results of a program to image the extended circumstellar envelopes of asymptotic giant branch (AGB) stars in dust-scattered Galactic light. The goal is to characterize the shapes of the envelopes to probe the mass-loss geometry and the presence of hidden binary companions. The observations consist of deep optical imaging of 22 AGB stars with high mass loss rates: 16 with the ESO 3.5 m NTT telescope, and the remainder with other telescopes. The circumstellar envelopes are detected in 15 objects, with mass loss rates > 2E-6 Msun/year. The surface brightness of the envelopes shows a strong decrease with Galactic radius, which indicates a steep radial gradient in the interstellar radiation field. The envelopes range from circular to elliptical in shape, and we characterize them by the ellipticity (E = major/minor axis) of iso-intensity contours. We find that about 50 percent of the envelopes are close to circular with E < 1.1, and others are more elliptical with about 20 percent with E > 1.2. We interpret the shapes in terms of populations of single stars and binaries whose envelopes are flattened by a companion. The distribution of E is qualitatively consistent with expectations based on population synthesis models of binary AGB stars. We also find that about 50 percent of the sample exhibit small-scale, elongated features in the central regions. We interpret these as the escape of light from the central star through polar holes, which are also likely produced by companions. Our observations of envelope flattening and polar holes point to a hidden population of companions within the circumstellar envelopes of AGB stars. These companions are expected to play an important role in the transition to post-AGB stars and the formation of planetary nebulae., Comment: 19 pages, 13 figures, color pictures in Appendix, accepted by A&A

Published
2013
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8. H5N1 Influenza: A Protean Pandemic Threat

Author

Guan, Y., Poon, L. L. M., Cheung, C. Y., Ellis, T. M., Lim, W., Lipatov, A. S., Chan, K. H., Sturm-Ramirez, K. M., Cheung, C. L., Leung, Y. H. C., Yuen, K. Y., Webster, R. G., and Peiris, J. S. M.

Published
2004

9. GWAS meta-analysis of over 29,000 people with epilepsy identifies 26 risk loci and subtype-specific genetic architecture

Author

Stevelink, R, Campbell, C, Chen, S, Abou-Khalil, B, Adesoji, OM, Afawi, Z, Amadori, E, Anderson, A, Anderson, J, Andrade, DM, Annesi, G, Auce, P, Avbersek, A, Bahlo, M, Baker, MD, Balagura, G, Balestrini, S, Barba, C, Barboza, K, Bartolomei, F, Bast, T, Baum, L, Baumgartner, T, Baykan, B, Bebek, N, Becker, AJ, Becker, F, Bennett, CA, Berghuis, B, Berkovic, SF, Beydoun, A, Bianchini, C, Bisulli, F, Blatt, I, Bobbili, DR, Borggraefe, I, Bosselmann, C, Braatz, V, Bradfield, JP, Brockmann, K, Brody, LC, Buono, RJ, Busch, RM, Caglayan, H, Campbell, E, Canafoglia, L, Canavati, C, Cascino, GD, Castellotti, B, Catarino, CB, Cavalleri, GL, Cerrato, F, Chassoux, F, Cherny, SS, Cheung, C-L, Chinthapalli, K, Chou, I-J, Chung, S-K, Churchhouse, C, Clark, PO, Cole, AJ, Compston, A, Coppola, A, Cosico, M, Cossette, P, Craig, JJ, Cusick, C, Daly, MJ, Davis, LK, de Haan, G-J, Delanty, N, Depondt, C, Derambure, P, Devinsky, O, Di Vito, L, Dlugos, DJ, Doccini, V, Doherty, CP, El-Naggar, H, Elger, CE, Ellis, CA, Eriksson, JG, Faucon, A, Feng, Y-CA, Ferguson, L, Ferraro, TN, Ferri, L, Feucht, M, Fitzgerald, M, Fonferko-Shadrach, B, Fortunato, F, Franceschetti, S, Franke, A, French, JA, Freri, E, Gagliardi, M, Gambardella, A, Geller, EB, Giangregorio, T, Gjerstad, L, Glauser, T, Goldberg, E, Goldman, A, Granata, T, Greenberg, DA, Guerrini, R, Gupta, N, Haas, KF, Hakonarson, H, Hallmann, K, Hassanin, E, Hegde, M, Heinzen, EL, Helbig, I, Hengsbach, C, Heyne, HO, Hirose, S, Hirsch, E, Hjalgrim, H, Howrigan, DP, Hucks, D, Hung, P-C, Iacomino, M, Imbach, LL, Inoue, Y, Ishii, A, Jamnadas-Khoda, J, Jehi, L, Johnson, MR, Kalviainen, R, Kamatani, Y, Kanaan, M, Kanai, M, Kantanen, A-M, Kara, B, Kariuki, SM, Kasperaviciute, D, Trenite, DK-N, Kato, M, Kegele, J, Kesim, Y, Khoueiry-Zgheib, N, King, C, Kirsch, HE, Klein, KM, Kluger, G, Knake, S, Knowlton, RC, Koeleman, BPC, Korczyn, AD, Koupparis, A, Kousiappa, I, Krause, R, Krenn, M, Krestel, H, Krey, I, Kunz, WS, Kurki, MI, Kurlemann, G, Kuzniecky, R, Kwan, P, Labate, A, Lacey, A, Lal, D, Landoulsi, Z, Lau, Y-L, Lauxmann, S, Leech, SL, Lehesjoki, A-E, Lemke, JR, Lerche, H, Lesca, G, Leu, C, Lewin, N, Lewis-Smith, D, Li, GH-Y, Li, QS, Licchetta, L, Lin, K-L, Lindhout, D, Linnankivi, T, Lopes-Cendes, I, Lowenstein, DH, Lui, CHT, Madia, F, Magnusson, S, Marson, AG, May, P, McGraw, CM, Mei, D, Mills, JL, Minardi, R, Mirza, N, Moller, RS, Molloy, AM, Montomoli, M, Mostacci, B, Muccioli, L, Muhle, H, Mueller-Schlueter, K, Najm, IM, Nasreddine, W, Neale, BM, Neubauer, B, Newton, CRJC, Noethen, MM, Nothnagel, M, Nuernberg, P, O'Brien, TJ, Okada, Y, Olafsson, E, Oliver, KL, Ozkara, C, Palotie, A, Pangilinan, F, Papacostas, SS, Parrini, E, Pato, CN, Pato, MT, Pendziwiat, M, Petrovski, S, Pickrell, WO, Pinsky, R, Pippucci, T, Poduri, A, Pondrelli, F, Powell, RHW, Privitera, M, Rademacher, A, Radtke, R, Ragona, F, Rau, S, Rees, MI, Regan, BM, Reif, PS, Rhelms, S, Riva, A, Rosenow, F, Ryvlin, P, Saarela, A, Sadleir, LG, Sander, JW, Sander, T, Scala, M, Scattergood, T, Schachter, SC, Schankin, CJ, Scheffer, IE, Schmitz, B, Schoch, S, Schubert-Bast, S, Schulze-Bonhage, A, Scudieri, P, Sham, P, Sheidley, BR, Shih, JJ, Sills, GJ, Sisodiya, SM, Smith, MC, Smith, PE, Sonsma, ACM, Speed, D, Sperling, MR, Stefansson, H, Stefansson, K, Steinhoff, BJ, Stephani, U, Stewart, WC, Stipa, C, Striano, P, Stroink, H, Strzelczyk, A, Surges, R, Suzuki, T, Tan, KM, Taneja, RS, Tanteles, GA, Tauboll, E, Thio, LL, Thomas, GN, Thomas, RH, Timonen, O, Tinuper, P, Todaro, M, Topaloglu, P, Tozzi, R, Tsai, M-H, Tumiene, B, Turkdogan, D, Unnsteinsdottir, U, Utkus, A, Vaidiswaran, P, Valton, L, van Baalen, A, Vetro, A, Vining, EPG, Visscher, F, von Brauchitsch, S, von Wrede, R, Wagner, RG, Weber, YG, Weckhuysen, S, Weisenberg, J, Weller, M, Widdess-Walsh, P, Wolff, M, Wolking, S, Wu, D, Yamakawa, K, Yang, W, Yapici, Z, Yucesan, E, Zagaglia, S, Zahnert, F, Zara, F, Zhou, W, Zimprich, F, Zsurka, G, Ali, QZ, Stevelink, R, Campbell, C, Chen, S, Abou-Khalil, B, Adesoji, OM, Afawi, Z, Amadori, E, Anderson, A, Anderson, J, Andrade, DM, Annesi, G, Auce, P, Avbersek, A, Bahlo, M, Baker, MD, Balagura, G, Balestrini, S, Barba, C, Barboza, K, Bartolomei, F, Bast, T, Baum, L, Baumgartner, T, Baykan, B, Bebek, N, Becker, AJ, Becker, F, Bennett, CA, Berghuis, B, Berkovic, SF, Beydoun, A, Bianchini, C, Bisulli, F, Blatt, I, Bobbili, DR, Borggraefe, I, Bosselmann, C, Braatz, V, Bradfield, JP, Brockmann, K, Brody, LC, Buono, RJ, Busch, RM, Caglayan, H, Campbell, E, Canafoglia, L, Canavati, C, Cascino, GD, Castellotti, B, Catarino, CB, Cavalleri, GL, Cerrato, F, Chassoux, F, Cherny, SS, Cheung, C-L, Chinthapalli, K, Chou, I-J, Chung, S-K, Churchhouse, C, Clark, PO, Cole, AJ, Compston, A, Coppola, A, Cosico, M, Cossette, P, Craig, JJ, Cusick, C, Daly, MJ, Davis, LK, de Haan, G-J, Delanty, N, Depondt, C, Derambure, P, Devinsky, O, Di Vito, L, Dlugos, DJ, Doccini, V, Doherty, CP, El-Naggar, H, Elger, CE, Ellis, CA, Eriksson, JG, Faucon, A, Feng, Y-CA, Ferguson, L, Ferraro, TN, Ferri, L, Feucht, M, Fitzgerald, M, Fonferko-Shadrach, B, Fortunato, F, Franceschetti, S, Franke, A, French, JA, Freri, E, Gagliardi, M, Gambardella, A, Geller, EB, Giangregorio, T, Gjerstad, L, Glauser, T, Goldberg, E, Goldman, A, Granata, T, Greenberg, DA, Guerrini, R, Gupta, N, Haas, KF, Hakonarson, H, Hallmann, K, Hassanin, E, Hegde, M, Heinzen, EL, Helbig, I, Hengsbach, C, Heyne, HO, Hirose, S, Hirsch, E, Hjalgrim, H, Howrigan, DP, Hucks, D, Hung, P-C, Iacomino, M, Imbach, LL, Inoue, Y, Ishii, A, Jamnadas-Khoda, J, Jehi, L, Johnson, MR, Kalviainen, R, Kamatani, Y, Kanaan, M, Kanai, M, Kantanen, A-M, Kara, B, Kariuki, SM, Kasperaviciute, D, Trenite, DK-N, Kato, M, Kegele, J, Kesim, Y, Khoueiry-Zgheib, N, King, C, Kirsch, HE, Klein, KM, Kluger, G, Knake, S, Knowlton, RC, Koeleman, BPC, Korczyn, AD, Koupparis, A, Kousiappa, I, Krause, R, Krenn, M, Krestel, H, Krey, I, Kunz, WS, Kurki, MI, Kurlemann, G, Kuzniecky, R, Kwan, P, Labate, A, Lacey, A, Lal, D, Landoulsi, Z, Lau, Y-L, Lauxmann, S, Leech, SL, Lehesjoki, A-E, Lemke, JR, Lerche, H, Lesca, G, Leu, C, Lewin, N, Lewis-Smith, D, Li, GH-Y, Li, QS, Licchetta, L, Lin, K-L, Lindhout, D, Linnankivi, T, Lopes-Cendes, I, Lowenstein, DH, Lui, CHT, Madia, F, Magnusson, S, Marson, AG, May, P, McGraw, CM, Mei, D, Mills, JL, Minardi, R, Mirza, N, Moller, RS, Molloy, AM, Montomoli, M, Mostacci, B, Muccioli, L, Muhle, H, Mueller-Schlueter, K, Najm, IM, Nasreddine, W, Neale, BM, Neubauer, B, Newton, CRJC, Noethen, MM, Nothnagel, M, Nuernberg, P, O'Brien, TJ, Okada, Y, Olafsson, E, Oliver, KL, Ozkara, C, Palotie, A, Pangilinan, F, Papacostas, SS, Parrini, E, Pato, CN, Pato, MT, Pendziwiat, M, Petrovski, S, Pickrell, WO, Pinsky, R, Pippucci, T, Poduri, A, Pondrelli, F, Powell, RHW, Privitera, M, Rademacher, A, Radtke, R, Ragona, F, Rau, S, Rees, MI, Regan, BM, Reif, PS, Rhelms, S, Riva, A, Rosenow, F, Ryvlin, P, Saarela, A, Sadleir, LG, Sander, JW, Sander, T, Scala, M, Scattergood, T, Schachter, SC, Schankin, CJ, Scheffer, IE, Schmitz, B, Schoch, S, Schubert-Bast, S, Schulze-Bonhage, A, Scudieri, P, Sham, P, Sheidley, BR, Shih, JJ, Sills, GJ, Sisodiya, SM, Smith, MC, Smith, PE, Sonsma, ACM, Speed, D, Sperling, MR, Stefansson, H, Stefansson, K, Steinhoff, BJ, Stephani, U, Stewart, WC, Stipa, C, Striano, P, Stroink, H, Strzelczyk, A, Surges, R, Suzuki, T, Tan, KM, Taneja, RS, Tanteles, GA, Tauboll, E, Thio, LL, Thomas, GN, Thomas, RH, Timonen, O, Tinuper, P, Todaro, M, Topaloglu, P, Tozzi, R, Tsai, M-H, Tumiene, B, Turkdogan, D, Unnsteinsdottir, U, Utkus, A, Vaidiswaran, P, Valton, L, van Baalen, A, Vetro, A, Vining, EPG, Visscher, F, von Brauchitsch, S, von Wrede, R, Wagner, RG, Weber, YG, Weckhuysen, S, Weisenberg, J, Weller, M, Widdess-Walsh, P, Wolff, M, Wolking, S, Wu, D, Yamakawa, K, Yang, W, Yapici, Z, Yucesan, E, Zagaglia, S, Zahnert, F, Zara, F, Zhou, W, Zimprich, F, Zsurka, G, and Ali, QZ

Abstract

Epilepsy is a highly heritable disorder affecting over 50 million people worldwide, of which about one-third are resistant to current treatments. Here we report a multi-ancestry genome-wide association study including 29,944 cases, stratified into three broad categories and seven subtypes of epilepsy, and 52,538 controls. We identify 26 genome-wide significant loci, 19 of which are specific to genetic generalized epilepsy (GGE). We implicate 29 likely causal genes underlying these 26 loci. SNP-based heritability analyses show that common variants explain between 39.6% and 90% of genetic risk for GGE and its subtypes. Subtype analysis revealed markedly different genetic architectures between focal and generalized epilepsies. Gene-set analyses of GGE signals implicate synaptic processes in both excitatory and inhibitory neurons in the brain. Prioritized candidate genes overlap with monogenic epilepsy genes and with targets of current antiseizure medications. Finally, we leverage our results to identify alternate drugs with predicted efficacy if repurposed for epilepsy treatment.

Published
2023

10. Elevated risk of multimorbidity post-COVID-19 infection: protective effect of vaccination.

Author

Lai, F T T, Liu, W, Hu, Y, Wei, C, Chu, R Y K, Lum, D H, Leung, J C N, Cheng, F W T, Chui, C S L, Li, X, Wan, E Y F, Wong, C K H, Cheung, C L, Chan, E W Y, Hung, I F N, and Wong, I C K

Subjects
COMORBIDITY, COVID-19 pandemic, COVID-19, HEALTH facilities, VACCINATION
Abstract

Background It is unclear how the coronavirus disease 2019 (Covid-19) pandemic has affected multimorbidity incidence among those with one pre-existing chronic condition, as well as how vaccination could modify this association. Aim To examine the association of Covid-19 infection with multimorbidity incidence among people with one pre-existing chronic condition, including those with prior vaccination. Design Nested case–control study. Methods We conducted a territory-wide nested case–control study with incidence density sampling using Hong Kong electronic health records from public healthcare facilities and mandatory Covid-19 reports. People with one listed chronic condition (based on a list of 30) who developed multimorbidity during 1 January 2020–15 November 2022 were selected as case participants and randomly matched with up to 10 people of the same age, sex and with the same first chronic condition without having developed multimorbidity at that point. Conditional logistic regression was used to estimate adjusted odds ratios (aORs) of multimorbidity. Results In total, 127 744 case participants were matched with 1 230 636 control participants. Adjusted analysis showed that there were 28%-increased odds of multimorbidity following Covid-19 [confidence interval (CI) 22% to 36%] but only 3% (non-significant) with prior full vaccination with BNT162b2 or CoronaVac (95% CI −2% to 7%). Similar associations were observed in men, women, older people aged 65 or more, and people aged 64 or younger. Conclusions We found a significantly elevated risk of multimorbidity following a Covid-19 episode among people with one pre-existing chronic condition. Full vaccination significantly reduced this risk increase. [ABSTRACT FROM AUTHOR]

Published
2024
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16. Establishment of Multiple Sublineages of H5N1 Influenza Virus in Asia: Implications for Pandemic Control

Author

Chen, H., Smith, G. J. D., Li, K. S., Wang, J., Fan, X. H., Rayner, J. M., Vijaykrishna, D., Zhang, J. X., Zhang, L. J., Guo, C. T., Cheung, C. L., Xu, K. M., Duan, L., Huang, K., Qin, K., Leung, Y. H. C., Wu, W. L., Lu, H. R., Chen, Y., Xia, N. S., Naipospos, T. S. P., Yuen, K. Y., Hassan, S. S., Bahri, S., Nguyen, T. D., Webster, R. G., Peiris, J. S. M., and Guan, Y.

Published
2006
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28. Interactions of magnetized plasma flows in pulsed-power driven experiments

Author

Massachusetts Institute of Technology. Plasma Science and Fusion Center, Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Suttle, L G, Burdiak, G C, Cheung, C L, Clayson, T, Halliday, J W D, Hare, J D, Rusli, S, Russell, D R, Tubman, E R, Ciardi, A, Gomes Loureiro, Nuno F, Li, J, Frank, A, Lebedev, S V, Massachusetts Institute of Technology. Plasma Science and Fusion Center, Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Suttle, L G, Burdiak, G C, Cheung, C L, Clayson, T, Halliday, J W D, Hare, J D, Rusli, S, Russell, D R, Tubman, E R, Ciardi, A, Gomes Loureiro, Nuno F, Li, J, Frank, A, and Lebedev, S V

Abstract

A supersonic flow of magnetized plasma is produced by the application of a 1 MA-peak, 500 ns current pulse to a cylindrical arrangement of parallel wires, known as an inverse wire array. The plasma flow is produced by the J × B acceleration of the ablated wire material, and a magnetic field of several Tesla is embedded at source by the driving current. This setup has been used for a variety of experiments investigating the interactions of magnetized plasma flows. In experiments designed to investigate magnetic reconnection, the collision of counter-streaming flows, carrying oppositely directed magnetic fields, leads to the formation of a reconnection layer in which we observe ions reaching temperatures much greater than predicted by classical heating mechanisms. The breakup of this layer under the plasmoid instability is dependent on the properties of the inflowing plasma, which can be controlled by the choice of the wire array material. In other experiments, magnetized shocks were formed by placing obstacles in the path of the magnetized plasma flow. The pile-up of magnetic flux in front of a conducting obstacle produces a magnetic precursor acting on upstream electrons at the distance of the ion inertial length. This precursor subsequently develops into a steep density transition via ion-electron fluid decoupling. Obstacles which possess a strong private magnetic field affect the upstream flow over a much greater distance, providing an extended bow shock structure. In the region surrounding the obstacle the magnetic pressure holds off the flow, forming a void of plasma material, analogous to the magnetopause around planetary bodies with self-generated magnetic fields., Department of Energy (Awards DE-NA0003764, DE-F03-02NA00057, DE-SC-0001063, DE-SC0016215), National Science Foundation (Award DE-SC0016215), Air Force Office of Scientific Research (Grant FA9550-17-1-0036), Engineering and Physical Sciences Research Council (EPSRC) (Grant EP/ N013379/1)

Published
2020

29. Interactions of magnetized plasma flows in pulsed-power driven experiments

Author

Suttle, L G, primary, Burdiak, G C, additional, Cheung, C L, additional, Clayson, T, additional, Halliday, J W D, additional, Hare, J D, additional, Rusli, S, additional, Russell, D R, additional, Tubman, E R, additional, Ciardi, A, additional, Loureiro, N F, additional, Li, J, additional, Frank, A, additional, and Lebedev, S V, additional

Published
2019
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31. Local structures surrounding Zr in nanostructurally stabilized cubic zirconia: Structural origin of phase stability.

Author

Soo, Y. L., Chen, P. J., Huang, S. H., Shiu, T. J., Tsai, T. Y., Chow, Y. H., Lin, Y. C., Weng, S. C., Chang, S. L., Wang, G., Cheung, C. L., Sabirianov, R. F., Mei, W. N., Namavar, F., Haider, H., Garvin, K. L., Lee, J. F., Lee, H. Y., and Chu, P. P.

Subjects
ZIRCONIUM, NANOSTRUCTURES, ZIRCONIUM oxide, THIN films, EXTENDED X-ray absorption fine structure, NANOCRYSTALS, ION bombardment
Abstract

Local environment surrounding Zr atoms in the thin films of nanocrystalline zirconia (ZrO2) has been investigated by using the extended x-ray absorption fine structure (EXAFS) technique. These films prepared by the ion beam assisted deposition exhibit long-range structural order of cubic phase and high hardness at room temperature without chemical stabilizers. The local structure around Zr probed by EXAFS indicates a cubic Zr sublattice with O atoms located on the nearest tetragonal sites with respect to the Zr central atoms, as well as highly disordered locations. Similar Zr local structure was also found in a ZrO2 nanocrystal sample prepared by a sol-gel method. Variations in local structures due to thermal annealing were observed and analyzed. Most importantly, our x-ray results provide direct experimental evidence for the existence of oxygen vacancies arising from local disorder and distortion of the oxygen sublattice in nanocrystalline ZrO2. These oxygen vacancies are regarded as the essential stabilizing factor for the nanostructurally stabilized cubic zirconia. [ABSTRACT FROM AUTHOR]

Published
2008
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32. Trans-ethnic polygenic analysis supports genetic overlaps of lumbar disc degeneration with height, body mass index, and bone mineral density

Author

Zhou, X. (Xueya), Cheung, C.-L. (Ching-Lung), Karasugi, T. (Tatsuki), Karppinen, J. (Jaro), Samartzis, D. (Dino), Hsu, Y.-H. (Yi-Hsiang), Mak, T. S. (Timothy Shin-Heng), Song, Y.-Q. (You-Qiang), Chiba, K. (Kazuhiro), Kawaguchi, Y. (Yoshiharu), Li, Y. (Yan), Chan, D. (Danny), Cheung, K. M. (Kenneth Man-Chee), Ikegawa, S. (Shiro), Cheah, K. S. (Kathryn Song-Eng), Sham, P. C. (Pak Chung), Zhou, X. (Xueya), Cheung, C.-L. (Ching-Lung), Karasugi, T. (Tatsuki), Karppinen, J. (Jaro), Samartzis, D. (Dino), Hsu, Y.-H. (Yi-Hsiang), Mak, T. S. (Timothy Shin-Heng), Song, Y.-Q. (You-Qiang), Chiba, K. (Kazuhiro), Kawaguchi, Y. (Yoshiharu), Li, Y. (Yan), Chan, D. (Danny), Cheung, K. M. (Kenneth Man-Chee), Ikegawa, S. (Shiro), Cheah, K. S. (Kathryn Song-Eng), and Sham, P. C. (Pak Chung)

Abstract

Lumbar disc degeneration (LDD) is age-related break-down in the fibrocartilaginous joints between lumbar vertebrae. It is a major cause of low back pain and is conventionally assessed by magnetic resonance imaging (MRI). Like most other complex traits, LDD is likely polygenic and influenced by both genetic and environmental factors. However, genome-wide association studies (GWASs) of LDD have uncovered few susceptibility loci due to the limited sample size. Previous epidemiology studies of LDD also reported multiple heritable risk factors, including height, body mass index (BMI), bone mineral density (BMD), lipid levels, etc. Genetics can help elucidate causality between traits and suggest loci with pleiotropic effects. One such approach is polygenic score (PGS) which summarizes the effect of multiple variants by the summation of alleles weighted by estimated effects from GWAS. To investigate genetic overlaps of LDD and related heritable risk factors, we calculated the PGS of height, BMI, BMD and lipid levels in a Chinese population-based cohort with spine MRI examination and a Japanese case-control cohort of lumbar disc herniation (LDH) requiring surgery. Because most large-scale GWASs were done in European populations, PGS of corresponding traits were created using weights from European GWASs. We calibrated their prediction performance in independent Chinese samples, then tested associations with MRI-derived LDD scores and LDH affection status. The PGS of height, BMI, BMD and lipid levels were strongly associated with respective phenotypes in Chinese, but phenotype variances explained were lower than in Europeans which would reduce the power to detect genetic overlaps. Despite of this, the PGS of BMI and lumbar spine BMD were significantly associated with LDD scores; and the PGS of height was associated with the increased the liability of LDH. Furthermore, linkage disequilibrium score regression suggested that, osteoarthritis, another degenerative disorde

Published
2018

48. Ethnic difference of clinical vertebral fracture risk

Author

Bow, C. H., primary, Cheung, E., additional, Cheung, C. L., additional, Xiao, S. M., additional, Loong, C., additional, Soong, C., additional, Tan, K. C., additional, Luckey, M. M., additional, Cauley, J. A., additional, Fujiwara, S., additional, and Kung, A. W. C., additional

Published
2011
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