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Search Results: 1 - 10 of 173331 matches for " Michael Ka Wah Li "
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Single Incision Laparoscopic Transabdominal Preperitoneal Repair for Strangulated Groin Hernia  [PDF]
Po Ching Cathy Ng, George Pei Cheung Yang, Michael Ka Wah Li
International Journal of Clinical Medicine (IJCM) , 2013, DOI: 10.4236/ijcm.2013.46A007
Abstract:

Introduction: Single incision laparoscopic surgery (SILS) has become more popular for various surgical procedures including hernia surgery. Initial results of SILS in elective hernia repair were comparable to those of conventional laparoscopic approaches. However the use of SILS in emergency case has not been widely reported. This study aimed to evaluate the feasibility of the use of single incision laparoscopic transabdominal preperitoneal (TAPP) repair for patients presenting with strangulated groin hernia. Method: Emergency single incision laparoscopic TAPP repair were performed in our unit from June 2011 onwards for selected patients. Retrospectively data including the patient demographics, operative time, type of hernia, hospital stay, complications and recurrence rate were collected and analyzed. Result: There were a total of five patients in this series from June 2011 to June 2012. The median age was 62 years old with a male to female ratio of 4:1. Four patients had unilateral hernia (one femoral and three inguinal hernias) and one had bilateral hernia (unilaterally strangulated femoral hernia and bilaterally reducible indirect inguinal hernia). The median operative time was 75 minutes for patients with unilateral repair. None of the patients required bowel resection. The conversion rate to either conventional laparoscopic or open repair was zero. The median hospital stay was 2 days. No major complication or recurrence was detected. Conclusion: This series showed that single port laparoscopic TAPP repair for strangulated groin hernia is a feasible option with no major complication reported.

Management of Recurrent Large Bowel Obstruction Due to Stent Occlusion by ‘Stent-Over-Stent’: A Case Report and Literature Review  [PDF]
D. Yi-Po Tsang, Hester Yui-Shan Cheung, Cliff Chi-Chiu Chung, Michael Ka-Wah Li
Surgical Science (SS) , 2011, DOI: 10.4236/ss.2011.28091
Abstract: Endoscopic stenting for malignant large bowel obstruction is common nowadays. However, recurrent obstruction secondary to stent occlusion due to tumour ingrowth or overgrowth might occur. We reported a case of a 70-year-old man with large bowel obstruction initially treated with colonic stenting. It was complicated with recurrent intestinal obstruction, with colonoscopy showing stent blockage by tumour ingrowth over distal part of the stent. Successful endoscopic implantation of additional colonic stent over the old stent was achieved and intestinal obstruction was resolved afterwards.
X-ray Signatures of Non-Equilibrium Ionization Effects in Galaxy Cluster Accretion Shock Regions
Ka-Wah Wong,Craig L. Sarazin,Li Ji
Physics , 2010, DOI: 10.1088/0004-637X/727/2/126
Abstract: The densities in the outer regions of clusters of galaxies are very low, and the collisional timescales are very long. As a result, heavy elements will be under-ionized after they have passed through the accretion shock. We have studied systematically the effects of non-equilibrium ionization for relaxed clusters in the LambdaCDM cosmology using one-dimensional hydrodynamic simulations. We found that non-equilibrium ionization effects do not depend on cluster mass but depend strongly on redshift which can be understood by self-similar scaling arguments. The effects are stronger for clusters at lower redshifts. We present X-ray signatures such as surface brightness profiles and emission lines in detail for a massive cluster at low redshift. In general, soft emission (0.3-1.0 keV) is enhanced significantly by under-ionization, and the enhancement can be nearly an order of magnitude near the shock radius. The most prominent non-equilibrium ionization signature we found is the O VII and O VIII line ratio. The ratios for non-equilibrium ionization and collisional ionization equilibrium models are different by more than an order of magnitude at radii beyond half of the shock radius. These non-equilibrium ionization signatures are equally strong for models with different non-adiabatic shock electron heating efficiencies. We have also calculated the detectability of the O VII and O VIII lines with the future International X-ray Observatory (IXO). Depending on the line ratio measured, we conclude that an exposure of ~130-380 ksec on a moderate-redshift, massive regular cluster with the X-ray Microcalorimeter Spectrometer (XMS) on the IXO will be sufficient to provide a strong test for the non-equilibrium ionization model.
Effects of the Non-Equipartition of Electrons and Ions in the Outskirts of Relaxed Galaxy Clusters
Ka-Wah Wong,Craig L. Sarazin
Physics , 2009, DOI: 10.1088/0004-637X/707/2/1141
Abstract: (abridged) We have studied the effects of electron-ion non-equipartition in the outer regions of relaxed clusters for a wide range of masses in the \LambdaCDM cosmology using one-dimensional hydrodynamic simulations. The effects of the non-adiabatic electron heating efficiency, \beta, on the degree of non-equipartition are also studied. Using the gas fraction f_gas = 0.17 (which is the upper limit for a cluster), we give a conservative lower limit of the non-equipartition effect on clusters. Beyond the virial radius, the non-equipartition effect depends rather strongly on \beta, and such a strong dependence at the shock radius can be used to distinguish shock heating models or constrain the shock heating efficiency of electrons. We have also studied systematically the signatures of non-equipartition on X-ray and SZ observables. We have calculated the effect of non-equipartition on the projected temperature and X-ray surface brightness profiles using the MEKAL emission model. The non-equipartition effect can introduce a ~10% bias in the projected temperature at R_vir for a wide range of \beta. We also found that the effect of non-equipartition on the projected temperature profiles can be enhanced by increasing metallicity. We found that for our model in the \LambdaCDM Universe, the integrated SZ bias, Y_{non-eq}/Y_{eq}, evolves slightly (at a percentage level) with redshift, which is in contrast to the self-similar model in the Einstein-de Sitter Universe. This may introduce biases in cosmological studies using the f_gas technique. We discussed briefly whether the equipartition and non-equipartition models near the shock region can be distinguished by future radio observations with, for example, ALMA.
SOAPdenovo-Trans: De novo transcriptome assembly with short RNA-Seq reads
Yinlong Xie,Gengxiong Wu,Jingbo Tang,Ruibang Luo,Jordan Patterson,Shanlin Liu,Weihua Huang,Guangzhu He,Shengchang Gu,Shengkang Li,Xin Zhou,Tak-Wah Lam,Yingrui Li,Xun Xu,Gane Ka-Shu Wong,Jun Wang
Quantitative Biology , 2013,
Abstract: Motivation: Transcriptome sequencing has long been the favored method for quickly and inexpensively obtaining the sequences for a large number of genes from an organism with no reference genome. With the rapidly increasing throughputs and decreasing costs of next generation sequencing, RNA-Seq has gained in popularity; but given the typically short reads (e.g. 2 x 90 bp paired ends) of this technol- ogy, de novo assembly to recover complete or full-length transcript sequences remains an algorithmic challenge. Results: We present SOAPdenovo-Trans, a de novo transcriptome assembler designed specifically for RNA-Seq. Its performance was evaluated on transcriptome datasets from rice and mouse. Using the known transcripts from these well-annotated genomes (sequenced a decade ago) as our benchmark, we assessed how SOAPdenovo- Trans and two other popular software handle the practical issues of alternative splicing and variable expression levels. Our conclusion is that SOAPdenovo-Trans provides higher contiguity, lower redundancy, and faster execution. Availability and Implementation: Source code and user manual are at http://sourceforge.net/projects/soapdenovotrans/ Contact: xieyl@genomics.cn or bgi-soap@googlegroups.com
The Impact of Non-Equipartition on Cosmological Parameter Estimation from Sunyaev-Zel'dovich Surveys
Ka-Wah Wong,Craig L. Sarazin,Daniel R. Wik
Physics , 2010, DOI: 10.1088/0004-637X/719/1/1
Abstract: The collisionless accretion shock at the outer boundary of a galaxy cluster should primarily heat the ions instead of electrons since they carry most of the kinetic energy of the infalling gas. Near the accretion shock, the density of the intracluster medium is very low and the Coulomb collisional timescale is longer than the accretion timescale. Electrons and ions may not achieve equipartition in these regions. Numerical simulations have shown that the Sunyaev-Zel'dovich observables (e.g., the integrated Comptonization parameter Y) for relaxed clusters can be biased by a few percent. The Y-mass relation can be biased if non-equipartition effects are not properly taken into account. Using a set of hydrodynamical simulations, we have calculated three potential systematic biases in the Y-mass relations introduced by non-equipartition effects during the cross-calibration or self-calibration when using the galaxy cluster abundance technique to constraint cosmological parameters. We then use a semi-analytic technique to estimate the non-equipartition effects on the distribution functions of Y (Y functions) determined from the extended Press-Schechter theory. Depending on the calibration method, we find that non-equipartition effects can induce systematic biases on the Y functions, and the values of the cosmological parameters Omega_8, sigma_8, and the dark energy equation of state parameter w can be biased by a few percent. In particular, non-equipartition effects can introduce an apparent evolution in w of a few percent in all of the systematic cases we considered. Techniques are suggested to take into account the non-equipartition effect empirically when using the cluster abundance technique to study precision cosmology. We conclude that systematic uncertainties in the Y-mass relation of even a few percent can introduce a comparable level of biases in cosmological parameter measurements.
A Gentleman with Anemia and Cholestasis
Siu-Tong Law,Wai-Ki Lee,Michael Kin-Kong Li,Ka-Ho Lok
Case Reports in Medicine , 2010, DOI: 10.1155/2010/536207
Abstract: Primary sclerosing cholangitis is a rare cause of cholestasis caused by progressive inflammation and fibrosis of both intrahepatic and extrahepatic bile ducts leading to multifocal ductal strictures. Herein, we report a case of primary sclerosing cholangitis and inflammatory bowel disease. The concomitant diagnosis of these two diseases is not typical. The management includes the treatment of inflammatory bowel disease and potential complications of primary sclerosing cholangitis, including dominant strictures of bile duct, portal hypertension, gallbladder diseases, cholangiocarcinoma, and colonoscopic surveillance.
Patient beliefs and attitudes towards the acceptability of receiving alcohol use enquiry from general practitioners: a literature review
Louis Leong,Chun Wah Michael Tam
PeerJ , 2015, DOI: 10.7287/peerj.preprints.439v1
Abstract: Background: Routine use of alcohol screening questionnaires is recommended in primary care, but patient beliefs and attitudes towards the acceptability of receiving alcohol enquiry from general practitioners (GPs) are unclear.
Advanced Metering Infrastructure for Electric Vehicle Charging  [PDF]
Lun Ka Lam, King Tim Ko, Hoi Yan Tung, Hoi Ching Tung, Wah Ching Lee, Kim Fung Tsang, Loi Lei Lai
Smart Grid and Renewable Energy (SGRE) , 2011, DOI: 10.4236/sgre.2011.24036
Abstract: The widely adoption of Electric Vehicle (EV) has been identified as a major challenge for future development of smart grids. The ever increasing electric vehicle charging further increases the energy demand. This paper reports the development of an Advanced Metering Infrastructure (AMI) as an effective tool to reshape the load profile of EV charging by adopting appropriate demand side management strategy. This paper presents a total solution for EV charging service platform (EVAMI) based on power line and internet communication. It must be stressed that the development of Third Party Customer Service Platform in this investigation facilitates a single bill to be issued to EV owners. Hence, EV owners understand their energy usage and thus may perform energy saving activity efficiently. Experiment and evaluation of the proposed system show that the throughput achieved is about 5 Mbps at 10 ms end to end delay in Power line Communication. By introducing two dimensional dynamic pricing and charging schedule, the proposed EVAMI successfully reduces 36% peak consumption and increases the “off peak” consumption by 54%. Therefore the EVAMI does not only reduce the peak consumption but also relocates the energy demand effectively.
A Study of Address Shortage in a Tree Based ZigBee Network for Mobile Health Applications  [PDF]
Ka Lun Lam, Hoi Yan Tung, King Tim Ko, Kim Fung Tsang, Hoi Ching Tung, Yat Wah Leung, Wing Hong Lau
Wireless Sensor Network (WSN) , 2012, DOI: 10.4236/wsn.2012.45021
Abstract: There are increasing demands for mobile health applications. This paper reports the development of a mobile health profile which dedicates to mobile applications. The mobile health profile is developed in association with the ZigBee Health Care profile and the IEEE 11073 standard which is normally applied to non-mobile applications. Since mobile sensors have to be carried by patients, the mobile health profile must facilitate mobility. In this investigation, a ZigBee fixed-mobile network (ZFMN) is defined and developed to supplement the ZigBee Health Care Profile for patient monitoring. The mobility study of ZigBee is performed using a random waypoint OPNET simulation model. In a ZFMN, the critical issue of address shortage is identified and discussed. It is analyzed that the problematic address shortage in a ZFMN may generate a huge amount of orphaned end devices and thus the packet drop percentage may potentially rise to 70%, rendering the network unable to function properly. Without introducing additional governing schemes, it is evaluated that the communication of the entire ZigBee network may paralyze. Further vigorous test are performed (by OPNET) on the communication capability of ZFMN when devices are randomly moving and sending data in 1s. It is vital to point out that under the adverse condition of address shortage, the performance of a ZFMN is still encouraging as long as the packet drop percentage has been kept below 3% before running out of address. The conclusion drawn in this analysis is that the packet drop percentage should be kept below 3% to provide a satisfactory QoS for an effective mobile health application using ZFMN such as patient monitoring. Such finding is also important for other future mobile application design of ZigBee. The address shortage issue is left as an open problem that needs attention for a resolution.
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