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Search Results: 1 - 10 of 210985 matches for " W. K. Lo "
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Field-induced structure transformation in electrorheological solids
C. K. Lo,K. W. Yu
Physics , 2001, DOI: 10.1103/PhysRevE.64.031501
Abstract: We have computed the local electric field in a body-centered tetragonal (BCT) lattice of point dipoles via the Ewald-Kornfeld formulation, in an attempt to examine the effects of a structure transformation on the local field strength. For the ground state of an electrorheological solid of hard spheres, we identified a novel structure transformation from the BCT to the face-centered cubic (FCC) lattices by changing the uniaxial lattice constant c under the hard sphere constraint. In contrast to the previous results, the local field exhibits a non-monotonic transition from BCT to FCC. As c increases from the BCT ground state, the local field initially decreases rapidly towards the isotropic value at the body-centered cubic lattice, decreases further, reaching a minimum value and increases, passing through the isotropic value again at an intermediate lattice, reaches a maximum value and finally decreases to the FCC value. An experimental realization of the structure transformation is suggested. Moreover, the change in the local field can lead to a generalized Clausius-Mossotti equation for the BCT lattices.
Effects of geometric anisotropy on local field distribution: Ewald-Kornfeld formulation
C. K. Lo,Jones T. K. Wan,K. W. Yu
Physics , 2001, DOI: 10.1088/0953-8984/13/6/311
Abstract: We have applied the Ewald-Kornfeld formulation to a tetragonal lattice of point dipoles, in an attempt to examine the effects of geometric anisotropy on the local field distribution. The various problems encountered in the computation of the conditionally convergent summation of the near field are addressed and the methods of overcoming them are discussed. The results show that the geometric anisotropy has a significant impact on the local field distribution. The change in the local field can lead to a generalized Clausius-Mossotti equation for the anisotropic case.
Self-Esteem, Self-Efficacy and Deviant Behaviour of Young People in Hong Kong  [PDF]
T. Wing Lo, Christopher H. K. Cheng, Dennis S. W. Wong, Tina L. Rochelle, Sharon I. Kwok
Advances in Applied Sociology (AASoci) , 2011, DOI: 10.4236/aasoci.2011.11004
Abstract: This study was designed to explore the psychological and social correlates of deviant behaviour in a sample of Hong Kong school students. Findings revealed that their deviant behaviour was significantly and positively correlated with rebelliousness and susceptibility to negative peer influence. While weak direct relationships were found between self-efficacy, self-esteem and deviant behaviour in general, we found “bullying/vandalism”, “verbally/physically attacking parents”, “lack of motivation to study”, and “verbally/physically attacking teachers” had significant effects with “self-esteem and/or self-efficacy”. The present study concludes that changing the delinquents’ deviant identity is essential; the identity-rebuilding process would strengthen their self-image and prevent them from going astray.
The Choice of Peritoneal Dialysis Catheter Implantation Technique by Nephrologists
T. Yip,S. L. Lui,W. K. Lo
International Journal of Nephrology , 2013, DOI: 10.1155/2013/940106
Abstract:
Managing the Accessibility on Mass Public Transit: the Case of Hong Kong
Hong K Lo,Siman Tang,David Z.W. Wang
Journal of Transport and Land Use , 2008,
Abstract: Public transit services (PTS) improve mobility and accessibility, and reduce car dependence. It is ideal if PTS are financially sustainable, with affordable fares and expedient quality. The success of PTS on accessibility improvement can be reflected by their level of patronage: do travelers choose to use them in lieu of their private cars? PTS in Hong Kong are renowned for their quality and profitability, superbly addressing the accessibility need for the city; they carry over 90% of the 11 million daily trips. A comparison of the per capita train-car and bus-vehicle kilometer run of PTS in Hong Kong with those in London and Singapore, however, suggests that it is not purely the supply that affects the use or accessibility of PTS in Hong Kong. By tracing and analyzing the development of PTS in Hong Kong over the past two decades, we found evidence that the high level of accessibility on mass public transit in the territory can be attributed to the land use policy of developing compact, high-density township, accompanying transport policies of granting high priority to the development of mass transit facilities and providing ways to ensure the financial viability of privately operated PTS, especially the innovative approach of integrating the development of public transport facility and property so as to exploit their synergy. In this paper, we study and highlight elements that contribute to the development of high accessibility on mass public transit in Hong Kong.
The Choice of Peritoneal Dialysis Catheter Implantation Technique by Nephrologists
T. Yip,S. L. Lui,W. K. Lo
International Journal of Nephrology , 2013, DOI: 10.1155/2013/940106
Abstract: Peritoneal dialysis catheter (PDC) is the lifeline of peritoneal dialysis (PD) patients. One of the critical issues for successful PD is a well-functioning PDC which is timely inserted. It is the implantation technique rather than the catheter design that determines the outcome of the catheter. Dedication in acquiring the appropriate technique is vital to the success of a PD program. In this paper, we discuss the pros and cons of various techniques used for PDC implantation. A detailed description of PDC implantation by using the minilaparotomy method is presented. We strongly recommend mini-laparotomy as the method of choice for PDC implantation by nephrologists. Peritoneal dialysis (PD) is a well-established technique of renal replacement therapy in patients with end-stage renal disease (ESRD). The advantages of PD include preservation of residual renal function, better patient survival in the first few years, better quality of life and cost-effectiveness over hemodialysis [1–4]. Thus, PD is well suited to act as a first-line renal replacement therapy in an integrated approach to end-stage renal failure care. In Hong Kong, “PD-first” policy has been adopted since mid-1980s. Currently, up to 80% of ESRD patients on maintenance dialysis are on PD. It has provided a successful model for the PD first policy. For a PD program to succeed, access to peritoneal dialysis catheter (PDC) implantation must be timely and the procedure must be performed by an experienced operator with low catheter failure rates and complications. PDC can be implanted percutaneously or by open surgery (Table 1). The standard percutaneous placement includes the “trocar and cannula” method and the Seldinger technique, with variations like fluoroscopy-assisted or peritoneoscopy-assisted placement. Open surgical approach includes minilaparotomy and laparoscopic placement. Table 1: Comparison of different methods of peritoneal dialysis catheter implantation. In many centers, PDC is implanted by surgeons, either by minilaparotomy or laparoscopic approach. However, referral to surgeons usually causes delay in initiating PD therapy, for both the waiting time to see a surgeon and the time required to arrange the operation afterwards. The date of implantation is often not under the control of nephrologists and this may make timely implantation of a PDC an impossible dream. Some patients may be forced to remain on hemodialysis with a central venous catheter, which is associated with an accelerated decrease in residual renal function and high rates of bacteremia and mortality. Survival data
The Discovery of Sgr A*
W. M. Goss,Robert L. Brown,K. Y. Lo
Physics , 2003, DOI: 10.1002/asna.200385047
Abstract: The compact radio source Sgr A* is associated with a 3.6 million black hole at the center of the Milky Way. The radio source was discovered in February 1974 by Bruce Balick and Robert L.Brown. The National Radio Astronomy Observatory's Green Bank 35 km radio link interferometer was used. We discuss other observations in the years 1965-1985 as well as early VLBI observations. The name Sgr A* was used for the first time in 1982 by Robert L.Brown and has become the accepted name in the intervening years.
Rate Bounds for MIMO Relay Channels
Caleb K. Lo,Sriram Vishwanath,Robert W. Heath Jr
Mathematics , 2007,
Abstract: This paper considers the multi-input multi-output (MIMO) relay channel where multiple antennas are employed by each terminal. Compared to single-input single-output (SISO) relay channels, MIMO relay channels introduce additional degrees of freedom, making the design and analysis of optimal cooperative strategies more complex. In this paper, a partial cooperation strategy that combines transmit-side message splitting and block-Markov encoding is presented. Lower bounds on capacity that improve on a previously proposed non-cooperative lower bound are derived for Gaussian MIMO relay channels.
The Impact of Channel Feedback on Opportunistic Relay Selection for Hybrid-ARQ in Wireless Networks
Caleb K. Lo,Robert W. Heath Jr.,Sriram Vishwanath
Mathematics , 2007,
Abstract: This paper presents a decentralized relay selection protocol for a dense wireless network and describes channel feedback strategies that improve its performance. The proposed selection protocol supports hybrid automatic-repeat-request transmission where relays forward parity information to the destination in the event of a decoding error. Channel feedback is employed for refining the relay selection process and for selecting an appropriate transmission mode in a proposed adaptive modulation transmission framework. An approximation of the throughput of the proposed adaptive modulation strategy is presented, and the dependence of the throughput on system parameters such as the relay contention probability and the adaptive modulation switching point is illustrated via maximization of this approximation. Simulations show that the throughput of the proposed selection strategy is comparable to that yielded by a centralized selection approach that relies on geographic information.
Relay Subset Selection in Wireless Networks Using Partial Decode-and-Forward Transmission
Caleb K. Lo,Sriram Vishwanath,Robert W. Heath Jr
Mathematics , 2007,
Abstract: This paper considers the problem of selecting a subset of nodes in a two-hop wireless network to act as relays in aiding the communication between the source-destination pair. Optimal relay subset selection with the objective of maximizing the overall throughput is a difficult problem that depends on multiple factors including node locations, queue lengths and power consumption. A partial decode-and-forward strategy is applied in this paper to improve the tractability of the relay selection problem and performance of the overall network. Note that the number of relays selected ultimately determines the performance of the network. This paper benchmarks this performance by determining the net diversity achieved using the relays selected and the partial decode-and-forward strategy. This framework is subsequently used to further transform relay selection into a simpler relay placement problem, and two proximity-based approximation algorithms are developed to determine the appropriate set of relays to be selected in the network. Other selection strategies such as random relay selection and a greedy algorithm that relies on channel state information are also presented. This paper concludes by showing that the proposed proximity-based relay selection strategies yield near-optimal expected rates for a small number of selected relays.
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