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787 results on '"Wong, K. L."'

1. Too poor or too far? : partitioning the variability in hospital birth by poverty and travel time in four sub-Saharan countries

Author

Wong, K. L. M., Benova, L., Campbell, O. M., and Brady, O. J.

Subjects
362.1984
Abstract

Poverty and long travel time are barriers to using skilled care at birth, especially care provided at hospitals which can be located far and result in high direct and indirect costs. In parts of sub- Saharan Africa, about one third of births occur in hospitals. This thesis aimed to assess the relative contributions of poverty and long travel time to the probability of giving birth in a hospital in Kenya, Malawi, Nigeria and Tanzania. I first reviewed the literature related to measuring the distance/travel time between women and health facilities in sub-Saharan Africa. Although the measurements and standards adopted by included studies were diverse, the impeding effect of living far from health facilities on use of childbirth care was prominent. In the second study, we compared two approaches to create high-resolution poverty maps in Kenya, Malawi, Nigeria and Tanzania. We found that the spatial variation in poverty and its determinants differed across countries, which should be considered when choosing the most suitable mapping approach. For each country, we used the better-performing approach to construct a national poverty map. These maps showed the highest concentration of poverty in remote locations, where population density was low and the allocation of resources potentially expensive. Next, we assessed the wealth inequality in travel time to the nearest hospital and its trade-off against minimizing overall travel time in the four countries. Travel time was calculated by overlaying locations of the population, wealth subgroups and hospitals. We simulated alternative hospital locations to identify the shortest overall travel time and the narrowest equity gap possible. Results suggest that hospitals in the four countries are currently well placed to minimize overall travel time, but they create wide inequality gaps by wealth. Lastly, we assessed the relative contributions of poverty, travel time, and other factors on the probability of hospital birth in the four countries. Poverty and travel time were important, and they played different roles within and across countries, meaning different strategies are needed to increase hospital-based childbirth. Nonetheless, these strategies alone do not address all barriers, and further research of where they do not lead to the desire result is required to help devise tailor-made actions.

Published
2020
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7. Overhead Lines and Wildfires: Role of Outdoor Insulators: Prepared by a Task Force of the IEEE DEIS Outdoor Insulation Technical Committee

Author

Ghunem, R. A., El-Hag, A. H., Marzinotto, M., Nazir, M. T., Wong, K. L., and Jayaram, S. H.

Subjects
Electrical and Electronic Engineering, Electronic, Optical and Magnetic Materials
Abstract

Insulator leakage current is the primary root cause of pole fires; therefore, it is critical to recognize outdoor insulators as potential cause of wildfires.

Published
2022
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8. Long pulse high performance discharges in the DIII-D tokamak

Author

Luce, TC, Wade, MR, Politzer, PA, Allen, SL, Austin, ME, Baker, DR, Bray, B, Brennan, DP, Burrell, KH, Casper, TA, Chu, MS, DeBoo, JC, Doyle, EJ, Ferron, JR, Garofalo, AM, Gohil, P, Gorelov, IA, Greenfield, CM, Groebner, RJ, Heidbrink, WW, Hsieh, C-L, Hyatt, AW, Jayakumar, R, Kinsey, JE, La Haye, RJ, Lao, LL, Lasnier, CJ, Lazarus, EA, Leonard, AW, Lin-Liu, YR, Lohr, J, Mahdavi, MA, Makowski, MA, Murakami, M, Petty, CC, Pinsker, RI, Prater, R, Rettig, CL, Rhodes, TL, Rice, BW, Strait, EJ, Taylor, TS, Thomas, DM, Turnbull, AD, Watkins, JG, West, WP, and Wong, K-L

Subjects
Atomic, Molecular, Nuclear, Particle and Plasma Physics, Fluids & Plasmas
Abstract

Significant progress in obtaining high performance discharges lasting many energy confinement times in the DIII-D tokamak has been realized in recent experimental campaigns. Normalized performance ∼10 has been sustained for more than 5>E with qmin > 1.5. (The normalized performance is measured by the product βNH89, indicating the proximity to the conventional β limits and energy confinement quality, respectively.) These H mode discharges have an ELMing edge and β < 5%. The limit to increasing β is a resistive wall mode, rather than the tearing modes as previously observed. Confinement remains good despite qmin > 1. The global parameters were chosen to optimize the potential for fully non-inductive current sustainment at high performance, which is a key program goal for the DIII-D facility. Measurement of the current density and loop voltage profiles indicate that ≈75% of the current in the present discharges is sustained non-inductively. The remaining ohmic current is localized near the half-radius. The electron cyclotron heating system is being upgraded to replace this remaining current with ECCD. Density and β control, which are essential for operating advanced tokamak discharges, were demonstrated in ELMing H mode discharges with βNH89 ≈ 7 for up to 6.3 s or ≈34τE. These discharges appear to have stationary current profiles with qmin ≈ 1.05 in agreement with the current profile relaxation time ≈1.8 s.

Published
2001

9. Responsive Regulation of Energy Transfer in Lanthanide-Doped Nanomaterials Dispersed in Chiral Nematic Structure.

Author

Luo, Y, Liu, Q, He, P, Li, L, Zhang, Z, Li, X, Bao, G, Wong, K-L, Tanner, PA, Jiang, L, Luo, Y, Liu, Q, He, P, Li, L, Zhang, Z, Li, X, Bao, G, Wong, K-L, Tanner, PA, and Jiang, L

Abstract

The responsive control of energy transfer (ET) plays a key role in the broad applications of lanthanide-doped nanomaterials. Photonic crystals (PCs) are excellent materials for ET regulation. Among the numerous materials that can be used to fabricate PCs, chiral nematic liquid crystals are highly attractive due to their good photoelectric responsiveness and biocompatibility. Here, the mechanisms of ET and the photonic effect of chiral nematic structures on ET are introduced; the regulation methods of chiral nematic structures and the resulting changes in ET of lanthanide-doped nanomaterials are highlighted; and the challenges and promising opportunities for ET in chiral nematic structures are discussed.

Published
2023

10. Advanced tokamak physics in DIII-D

Author

Petty, CC, Luce, TC, Politzer, PA, Wade, MR, Allen, SL, Austin, ME, Bray, B, Burrell, KH, Casper, TA, Chu, MS, Ferron, JR, Fredrickson, ED, Garofalo, AM, Gohil, P, Gorelov, I, Greenfield, CM, Heidbrink, WW, Hsieh, C-L, Hyatt, AW, Jayakumar, R, Johnson, LC, Kinsey, JE, La Haye, RJ, Lao, LL, Lasnier, CJ, Lazarus, EA, Leonard, AW, Lin-Liu, YR, Lohr, J, Mahdavi, MA, Makowski, MA, McKee, GR, Murakami, M, Navratil, GA, Okabayashi, M, Petrie, TW, Pinsker, RI, Prater, R, Rettig, CL, Rhodes, TL, Rice, BW, Scoville, JT, Staebler, GM, Strait, EJ, Taylor, TS, Watkins, JG, West, WP, Wolf, NS, and Wong, K-L

Subjects
Atomic, Molecular, Nuclear, Particle and Plasma Physics, Other Physical Sciences, Fluids & Plasmas
Abstract

Advanced tokamaks seek to achieve a high bootstrap current fraction without sacrificing fusion power density or fusion gain. Good progress has been made towards the DIII-D research goal of demonstrating a high-β advanced tokamak plasma in steady state with a relaxed, fully non-inductive current profile and a bootstrap current fraction greater than 50%. The limiting factors for transport, stability, and current profile control in advanced operating modes are discussed in this paper.

Published
2000

11. Search for alpha driven BAEs in TFTR

Author

Heidbrink, WW, Batha, SH, Bell, RE, Chang, Z, Darrow, DS, Fang, J, Fredrickson, ED, James, RA, Levington, FM, Nazikian, R, Paul, SF, Ruskov, E, Sabbagh, SA, Santoro, RA, Strait, EJ, Synakowski, EJ, Taylor, G, Turnbull, AD, Wong, K-L, and Zweben, SJ

Subjects
Atomic, Molecular, Nuclear, Particle and Plasma Physics, Fluids & Plasmas
Abstract

A search for alpha driven beta-induced Alfvén eigenmodes (BAEs) was conducted in low current (1.0-1.6 MA) TFTR supershots. Stable high beta deuterium-tritium (DT) discharges were obtained with βp = 2.4 and a central alpha beta of 0.1%. Instabilities between 75 and 200 kHz were observed by magnetics probes in many DT discharges, but the activity was also present in deuterium-deuterium (DD) comparison discharges, indicating that these modes are not destabilized (principally) by the alpha particle population. Losses of fusion products are also similar in the two sets of discharges. Theoretical simulations confirm that the achieved alpha particle pressure is too small to produce instability.

Published
1996

12. Alpha particle losses from Tokamak Fusion Test Reactor deuterium–tritium plasmas

Author

Darrow, DS, Zweben, SJ, Batha, S, Budny, RV, Bush, CE, Chang, Z, Cheng, CZ, Duong, HH, Fang, J, Fisch, NJ, Fischer, R, Fredrickson, ED, Fu, GY, Heeter, RF, Heidbrink, WW, Herrmann, HW, Herrmann, MC, Hill, K, Jaeger, EF, James, R, Majeski, R, Medley, SS, Murakami, M, Petrov, M, Phillips, CK, Redi, MH, Ruskov, E, Spong, DA, Strait, EJ, Taylor, G, White, RB, Wilson, JR, Wong, K-L, and Zarnstorff, MC

Subjects
Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Classical Physics, Fluids & Plasmas
Abstract

Because alpha particle losses can have a significant influence on tokamak reactor viability, the loss of deuterium–tritium alpha particles from the Tokamak Fusion Test Reactor (TFTR) [K. M. McGuire et al., Phys. Plasmas 2, 2176 (1995)] has been measured under a wide range of conditions. In TFTR, first orbit loss and stochastic toroidal field ripple diffusion are always present. Other losses can arise due to magnetohydrodynamic instabilities or due to waves in the ion cyclotron range of frequencies. No alpha particle losses have yet been seen due to collective instabilities driven by alphas. Ion Bernstein waves can drive large losses of fast ions from TFTR, and details of those losses support one element of the alpha energy channeling scenario. © 1996, American Institute of Physics. All rights reserved.

Published
1996

22. A Molecule Carrier

Author

Wong, K. L., Pawin, G., Kwon, K.-Y., Lin, X., Jiao, T., Solanki, U., Fawcett, R. H. J., Bartels, L., Stolbov, S., and Rahman, T. S.

Published
2007
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23. Enhancing Hybrid Upconversion Nanosystems via Synergistic Effects of Moiety Engineered NIR Dyes

Author

Bao, G, Wen, S, Wang, W, Zhou, J, Zha, S, Liu, Y, Wong, K-L, and Jin, D

Subjects
Nanoscience & Nanotechnology
Abstract

Hybrid upconversion nanosystems have been reported to improve the low absorption efficiency of lanthanide-doped upconversion nanoparticles (UCNPs). However, the low quantum yield and poor photostability of NIR dyes pose challenges for practical uses. Here, we introduce a bulky moiety, 4-(1,2,2-triphenylvinyl)-1,1'-biphenyl (TPEO), to enhance its quantum yield by suppressing the bond rotation and improve the stability by deactivating the photoinduced oxidization. Compared with the conventional IR806, the formed NIR dye, TPEO-Cy, has been characterized to deliver three times higher quantum yield and seven times better photostability. Moreover, we take advantage of the strong affinity of sulfonate chains on the TPEO-Cy to bind to the surface of UCNPs. Taking together the synergistic effect, we have achieved a 242-fold upconversion emission enhancement over the benchmark of IR806-sensitized system and an ∼800 000-fold increase than the bare UCNPs. Our design of the NIR dyes suggests a new scope to search for more efficient upconversion nanohybrids.

Published
2021

28. Experimental Results from the TFTR Tokamak

Author

Hawryluk, R. J., Arunasalam, V., Bell, J. D., Bell, M. G., Bitter, M., Blanchard, W. R., Boody, F., Bretz, N., Budny, R., Bush, C. E., Callen, J. D., Cecchi, J. L., Cohen, S., Colchin, R. J., Combs, S. K., Coonrod, J., Davis, S. L., Dimock, D., Dylla, H. F., Efthimion, P. C., Emerson, L. C., England, A. C., Eubank, H. P., Fonck, R., Fredrickson, E., Goldston, R. J., Grisham, L. R., Grek, B., Groebner, R., Hendel, H., Hill, K. W., Hillis, D. L., Hinnov, E., Hiroe, S., Hulse, R., Hsuan, H., Johnson, D., Kaita, R., Kamperschroer, R., Kaye, S. M., Kilpatrick, S., Kugel, H., LaMarche, P. H., Little, R., Ma, C. H., Manos, D. M., Mansfield, D., McCann, R. T., McCarthy, M., McCune, D. C., McGuire, K., Meade, D. M., Medley, S. S., Milora, S. L., Mikkelsen, D. R., Morris, W., Mueller, D., Murakami, M., Nieschmidt, E., Owens, D. K., Pare, V. K., Park, H., Prichard, B., Ramsey, A., Rasmussen, D. A., Redi, M. H., Roquemore, A. L., Sauthoff, N. R., Schivell, J., Schmidt, G. L., Scott, S. D., Sesnic, S., Shimada, M., Simpkins, J. E., Sinnis, J., Stauffer, F., Stratton, B., Tait, G. D., Taylor, G., Thomas, C. E., Towner, H. H., Ulrickson, M., Von Goeler, S., Weiland, R., Wilgen, J. B., Williams, M., Wong, K. L., Yoshikawa, S., Young, K. M., Zarnstorff, M. C., and Zweben, S.

Published
1987

32. Correction to Energy transfer between Tb3+ and Eu3+ in LaPO4: Pulsed Versus Switched‐Off Continuous Wave Excitation.

Author

Luo, Y., Liu, Z., Wong, H.‐T., Zhou, L., Wong, K.‐L., Shiu, K. K., and Tanner, P. A.

Subjects
ENERGY transfer, EQUATIONS
Abstract

Energy transfer between Tb3+ and Eu3+ in LaPO4: pulsed versus switched‐off continuous wave excitation. Advanced Science 1900487 (1‐12), 2019. Advanced Science2019; 6: 1900487 (1‐12).There is a typographic error in Equation (5), which should read as "τD(s‐3)k+1Rs‐3" and not as written "τD(s‐3)k+1Rs‐3". Also, the headings in Table 1 are "[ms]−1" and not "[ms−1]".We apologize for this error.By Y. Luo; Z. Liu; H.‐T. Wong; L. Zhou; K.‐L. Wong; K. K. Shiu and P. A. TannerReported by Author; Author; Author; Author; Author; Author; Author [Extracted from the article]

Published
2024
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43. Charge exchange and fusion reaction measurements during compression experiments with neutral beam heating in the Tokamak Fusion Test Reactor

Author

Kaita, R, Heidbrink, WW, Hammett, GW, Chan, AA, England, AC, Hendel, HW, Medley, SS, Nieschmidt, E, Roquemore, AL, Scott, SD, Strachan, JD, Tait, GD, Taylor, G, Thomas, CE, and Wong, K-L

Subjects
Atomic, Molecular, Nuclear, Particle and Plasma Physics, Fluids & Plasmas
Abstract

Adiabatic toroidal compression experiments were performed in conjunction with high power neutral beam injection in the Tokamak Fusion Test Reactor (TFTR). Acceleration of beam ions to energies nearly twice the injection energy was measured with a charge exchange neutral particle analyser. Measurements were also made of 2.5 MeV neutrons and 15 MeV protons produced in fusion reactions between the deuterium beam ions and the thermal deuterium and3He ions, respectively. When the plasma was compressed, the d(d, n)3He fusion reaction rate increased by a factor of five, and the3He(d, p) α rate by a factor of twenty. These data were simulated with a bounce averaged Fokker-Planck program, which assumed conservation of angular momentum and magnetic moment during compression. The results indicate that the beam ion acceleration was consistent with adiabatic scaling. © 1986 IOP Publishing Ltd.

Published
1986

44. High-temperature plasmas in a tokamak fusion test reactor

Author

Strachan, JD, Bitter, M, Ramsey, AT, Zarnstorff, MC, Arunasalam, V, Bell, MG, Bretz, NL, Budny, R, Bush, CE, Davis, SL, Dylla, HF, Efthimion, PC, Fonck, RJ, Fredrickson, E, Furth, HP, Goldston, RJ, Grisham, LR, Grek, B, Hawryluk, RJ, Heidbrink, WW, Hendel, HW, Hill, KW, Hsuan, H, Jaehnig, KP, Jassby, DL, Jobes, F, Johnson, DW, Johnson, LC, Kaita, R, Kampershroer, J, Knize, RJ, Kozub, T, LeBlanc, B, Levinton, F, La Marche, PH, Manos, DM, Mansfield, DK, McGuire, K, McNeill, DH, Meade, DM, Medley, SS, Morris, W, Mueller, D, Nieschmidt, EB, Owens, DK, Park, H, Schivell, J, Schilling, G, Schmidt, GL, Scott, SD, Sesnic, S, Sinnis, JC, Stauffer, FJ, Stratton, BC, Tait, GD, Taylor, G, Towner, HH, Ulrickson, M, von Goeler, S, Wieland, R, Williams, MD, Wong, K-L, Yoshikawa, S, Young, KM, and Zweben, SJ

Subjects
Mathematical Sciences, Physical Sciences, Engineering, General Physics
Abstract

Neutral-beam heating of plasmas in the Tokamak Fusion Test Reactor at low preinjection densities [ne(0)1019 m-3] were characterized by Te(0)=6.5 keV, Ti(0)=20 keV, ne(0)=7×1019 m-3, E=170 msec, theta=2, and a d(d,n)3He neutron emission rate of 1016 sec-1. The ion temperature and the deuterium-fusion neutron yields were significantly higher than for previous tokamak experiments. The low initial densities were achieved by operation of the Tokamak Fusion Test Reactor with low plasma currents (1 MA) and by extensive limiter conditioning. © 1987 The American Physical Society.

Published
1987

49. Retracted: Disjunctive programming-tabu search (dp-ts) approach for job Shop scheduling problem

Author

Wong, K. L. and Nordin, S. Z.

Subjects
job shop scheduling, tabu search, disjunctive graph
Abstract

This article was withdrawn and retracted by the Journal of Fundamental and Applied Sciences and has been removed from AJOL at the request of the journal Editor in Chief and the organisers of the conference at which the articles were presented (www.iccmit.net). Please address any queries to editor@jfas.info.

Published
2018

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