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Search Results: 1 - 10 of 9249 matches for " Chi-Fai Lo "
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The Sum and Difference of Two Constant Elasticity of Variance Stochastic Variables  [PDF]
Chi-Fai Lo
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.411203

We have applied the Lie-Trotter operator splitting method to model the dynamics of both the sum and difference of two correlated constant elasticity of variance (CEV) stochastic variables. Within the Lie-Trotter splitting approximation, both the sum and difference are shown to follow a shifted CEV stochastic process, and approximate probability distributions are determined in closed form. Illustrative numerical examples are presented to demonstrate the validity and accuracy of these approximate distributions. These approximate probability distributions can be used to valuate two-asset options, e.g. spread options and basket options, where the CEV variables represent the forward prices of the underlying assets. Moreover, we believe that this new approach can be extended to study the algebraic sum of N CEV variables with potential applications in pricing multi-asset options.

A Simple Generalisation of Kirk’s Approximation for Multi-Asset Spread Options by the Lie-Trotter Operator Splitting Method  [PDF]
Chi-Fai Lo
Journal of Mathematical Finance (JMF) , 2014, DOI: 10.4236/jmf.2014.43016

In this paper, by means of the Lie-Trotter operator splitting method, we have presented a new unified approach not only to rigorously derive Kirk’s approximation but also to obtain a generalisation for multi-asset spread options in a straightforward manner. The derived price formula for the multi-asset spread option bears a great resemblance to Kirk’s approximation in the two-asset case. More importantly, our approach is able to provide a new perspective on Kirk’s approximation and the generalization; that is, they are simply equivalent to the Lie-Trotter operator splitting approximation to the Black-Scholes equation.

Stress and Coping Strategies among University Freshmen in Hong Kong: Validation of the Coping Strategy Indicator  [PDF]
Chi-Fai Lo
Psychology (PSYCH) , 2017, DOI: 10.4236/psych.2017.88081
Abstract: This study has examined the validation of the Coping Strategy Indicator (CSI) with the 12-item General Health Questionnaire (GHQ-12) as a criterion for a sample of Chinese university students in Hong Kong, which consists of one hundred and ninety-four freshmen from the local universities. The relationship between freshmen’s coping efforts and adjustment to university life in the Hong Kong context has been investigated, using the CSI as the measure of coping and the GHQ-12 as the screening instrument for mental health. The results indicate high internal consistency of the three CSI coping scales, implying that the CSI can be a valid instrument to assess the coping efforts of university students of Hong Kong. Moreover, the samples of freshmen are found to prefer positive coping strategies, and female students are more willing to seek social support than males in coping with stress.
Critically Discuss the Revival of Leptin for Obesity Therapy  [PDF]
Chi-Fai Lo
Psychology (PSYCH) , 2018, DOI: 10.4236/psych.2018.92014
Abstract: Obesity has created a very serious public health problem, and World Health Organisation has actually warned that there is an urgent need for multinational cooperation to stem the rise of obesity. More than 20 years ago the discovery of Leptin, which is an adipocyte-secreted hormone and primarily acts on the hypothalamic neurons to activate the regulation of energy homeostasis, created much interest in its potential use for the treatment of obesity, but the hope was soon lost after leptin failed to counteract common diet-induced obesity. In recent years some preclinical studies have surprisingly demonstrated that resistance to leptin can be reversed and the effects of leptin therapy can be amplified by several leptin sensitisers. This paper will critically discuss the plausible revival of leptin for obesity therapy with reference to research findings on various influencing factors contributing to the level of expression and secretion of leptin.
Critically Discuss the Effects of Sleep on Long-Term Memory  [PDF]
Chi-Fai Lo
Psychology (PSYCH) , 2018, DOI: 10.4236/psych.2018.94034
Abstract: In our modern societies, sleep is commonly viewed as a luxury rather than a necessity, and should be kept at a strict minimum to enhance productivity. However, recent empirical studies reveal that sleep does play a critical role in our learning and memory; in fact, it has been shown that good sleep quality, feeling rested at school and having a distinct bed time have been associated with better functioning at school. Although consensus on sleep’s contribution to the active processing of newly acquired memories has been established now, the question about exactly what underlying mechanisms are involved in the sleep-memory connection still remains unclear. This paper will critically discuss how sleep affects learning and memory with reference to current research findings.
Machiavellianism and Intimacy Attitudes in the Interpersonal Relationships  [PDF]
Chi-Fai Lo, Eva Chor-Bing Ng
Psychology (PSYCH) , 2019, DOI: 10.4236/psych.2019.104029
Abstract: The present study investigated the relation between Machiavellianism and intimacy attitudes in the interpersonal relationships. Male (N = 46) and female (N = 56) participants aged 18 to 51 years (M = 31.56, SD = 8.00) were recruited to complete a questionnaire containing Mach IV Scale (Christie & Geis, 1970) and Intimacy Attitude Scale-Revised (Amidon, Kumar, & Treadwell, 1983). The regression analysis has revealed that Machiavellianism is a reliable predictor of the intimacy attitude of an individual, and the hypothesis that Machiavellianism is negatively correlated with positive intimacy and positively correlated with negative intimacy has been confirmed.
The Effects of Ganoderma lucidum on Initial Events Related to the Bacillus Calmette-Guérin Efficacy and Toxicity on High-Risk Uroepithelial Cells: An in Vitro Preliminary Study  [PDF]
John Wai-Man Yuen, Mayur-Danny I. Gohel, Chi-Fai Ng
Chinese Medicine (CM) , 2013, DOI: 10.4236/cm.2013.42009

A novel prophylactic regimen is demanded for preventing bladder cancer recurrence, because of the high side-effect tolls of conventional adjuvant Bacillus Calmette-Guérin (BCG) immunotherapy, in addition to its only moderate efficacy. In vitro and animal studies have demonstrated the anti-cancer properties of a medicinal mushroom called Ganoderma lucidum (GL). In this study, a pre-malignant human uroepithelial cells (HUC-PC) model was utilized to compare the effectiveness between ethanol extract of GL (GLe) and BCG on interleukin-6 (IL-6) secretion and lactate dehydrogenase (LDH) cytotoxicity. Additionally, parameters relevant to the BCG efficacy and safety, including free soluble fibronectin (FN) and cell-surface glycosaminoglycans (GAGs) levels were tested, following the exposure of GLe to the cells. GLe at 100 μg/ml and BCG at 4.8 × 107 CFU were shown to induce equivalent levels of IL-6, suggesting the potential synergism, while the tested concentrations of GLe were non-cytotoxic. During the initial four hours of GLe exposure, the free FN concentrations in harvested media were significantly reduced that might facilitate the binding of BCG for uroepithelial internalization to enhance BCG efficacy. Furthermore, the cell membrane-bound GAGs levels of HUC-PC cells were significant increased in response to GLe to suggest cellular protection from BCG infection. In summary, current findings suggest the potential additive synergism of GLe with the BCG efficacy, as well as its protective effects, and thus reducing the BCG toxicity.

Synergistic Cytotoxic Effects of Ganoderma lucidum and Bacillus Calmette Guérin on Premalignant Urothelial HUC-PC Cells and Its Regulation on Proinflammatory Cytokine Secretion
John Wai-man Yuen,Mayur-Danny I. Gohel,Chi-fai Ng
Evidence-Based Complementary and Alternative Medicine , 2012, DOI: 10.1155/2012/147896
Abstract: Bacillus Calmette-Guérin (BCG) is conventionally used as an adjuvant immunotherapy to reduce the recurrence of bladder cancer. To address the issues of efficacy and safety, an ethanol extract of Ganoderma lucidum (GLe) was evaluated for its interaction with BCG. In a model of premalignant human uroepithelial cells (HUC-PC), GLe exerted immediate cytotoxic effects while BCG showed a delayed response, given that both were immunological active in inducing the secretion of interleukin (IL)-6, IL-8, and monocyte chemotactic protein-1 (MCP-1). Synergistic cytotoxic effects were observed when cells were either coincubated with both drugs or firstly preincubated with GLe. Synergism between GLe and BCG was demonstrated to achieve a complete cytostasis in 24 hours, and such effects were progressed in the subsequent 5 days. However, the pretreatment of GLe resulted in suppression of IL-6, IL-8, and MCP-1 secretions without affecting the cytotoxicity. Given that numerous proinflammatory cytokines are associated with the high side effects toll of BCG, results herein suggested the potential implications of GL to supplement the BCG immunotherapy in bladder cancer, for better efficacy and reducing side effects.
Late retroperitoneal recurrence of hepatocellular carcinoma 12 years after initial diagnosis
Tiffany Cho-Lam Wong, Ka-Fai To, Simon See-Ming Hou, Sidney Kam-Hung Yip, Chi-Fai Ng
World Journal of Gastroenterology , 2010,
Abstract: Hepatocellular carcinoma (HCC) is an aggressive tumor with poor long-term prognosis. Here, we present an unusual patient with a solitary recurrence of HCC in the right kidney 12 years after the initial diagnosis. This illustrates the importance of considering late recurrence in patients with a history of HCC and the management of these metastases.
A MicroRNA-7 Binding Site Polymorphism in HOXB5 Leads to Differential Gene Expression in Bladder Cancer
Junhua Luo, Qingqing Cai, Wei Wang, Hui Huang, Hong Zeng, Wang He, Weixi Deng, Hao Yu, Eddie Chan, Chi-fai NG, Jian Huang, Tianxin Lin
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0040127
Abstract: Purpose To investigate the biological function of HOXB5 in human bladder cancer and explore whether the HOXB5 3′-UTR SNP (1010A/G), which is located within the microRNA-7 binding site, was correlated with clinical features of bladder cancer. Methods Expression of HOXB5 in 35 human bladder cancer tissues and 8 cell lines were examined using real-time PCR and immunohistochemistry. Next, we explored the biological function of HOXB5 in vitro using cell proliferation, migration and colony formation assays. Using bioinformatics, a SNP (1010A/G) was found located within the microRNA-7 binding site in the 3′-UTR of HOXB5. Real-time PCR was used to test HOXB5 expression affected by different alleles. Finally, multivariate logistic regression analysis was used to determine the relationship between SNP (1010A/G) frequency and clinical features in 391 cases. Results HOXB5 was frequently over-expressed both in bladder cancer tissues and cell lines. Inhibition of HOXB5 suppressed the oncogenic function of cancer cells. Next, we demonstrated that a SNP (1010A/G), located within the microRNA-7 binding site in the 3′-UTR of HOXB5, could affect HOXB5 expression in bladder cancer mainly by differential binding activity of microRNA-7 and SNP-related mRNA stability. Finally, we also showed the frequency of 1010G genotype was higher in cancer group compared to normal controls and correlated with the risk of high grade and high stage. Conclusion HOXB5 is overexpressed in bladder cancer. A miRNA-binding SNP (1010A/G) located within 3′-UTR of HOXB5 is associated with gene expression and may be a promising prognostic factor for bladder cancer.
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