33 results on '"Tai-Shing Lau"'
Search Results
2. Deduction of paternity index from DNA mixture.
- Author
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Xiang Hai Liao, Tai Shing Lau, Ngan, Karenda Fai Ngor, and Jun Wang
- Subjects
Paternity testing -- Research ,Paternity testing -- Methods ,DNA testing -- Research ,DNA testing -- Methods ,Forensic genetics -- Research - Published
- 2002
3. Folklore-Based Learning on the Web—Pedagogy, Case Study, and Evaluation
- Author
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Jimmy H. M. Lee, Fong-Lok Lee, and Tai-Shing Lau
- Subjects
Cooperative learning ,Folklore ,business.industry ,Teaching method ,Situated learning ,05 social sciences ,050401 social sciences methods ,050301 education ,Experiential learning ,Computer Science Applications ,Education ,World Wide Web ,0504 sociology ,Active learning ,Pedagogy ,Mathematics education ,The Internet ,business ,Psychology ,0503 education ,Folk culture - Abstract
Folklore-based learning is a kind of situated learning paradigm in which students learn by solving problems embedded in a near-real situation. The proposed learning approach employs further interesting story plots from folklores as the background situation to motivate students to participate in learning activities. It is believed that such a paradigm has, on one hand, the advantages of helping students to learn in an authentic situation and, on the other, the provision of interesting story episodes as a stimulating agent for less initiated students. This article reports a folklore-based learning system based on the well-known Chinese folklore called “Tong Pak Fu and Chou Heung,” and its effects on learning the subject of probability by a group of 454 Hong Kong secondary school tsudents when compared with 3 teacher-guided methods. Results show that although no significant differences can be found among the different methods initially, when students with high pre-test scores were excluded the folklore-based learning group outperformed the other groups. Also, from student perception of the system it was found that the students prefer using this system to learn. Consider that no guidance on the subject matters was given to the students learning through this system, while students using the other methods were guided by experienced teachers, the results are very encouraging so that improvement and future developments to cover more topics are warranted.
- Published
- 2006
- Full Text
- View/download PDF
4. A note on D-optimal designs for models with and without an intercept
- Author
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Chongqi Zhang, Kim-Hung Li, and Tai-Shing Lau
- Subjects
Statistics and Probability ,Optimal design ,Polynomial regression ,Mathematical optimization ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Product model ,Regression analysis ,Statistics, Probability and Uncertainty ,D optimal ,Mathematics - Abstract
In this paper we give a sufficient condition under which theD-optimal design for a regression model without an intercept can be obtained from theD-optimal design for the corresponding model with an intercept by simply removing the origin from its support points. Examples are given to demonstrate the applications of the results.
- Published
- 2005
- Full Text
- View/download PDF
5. Stromal expression of vascular endothelial growth factor correlates with tumor grade and microvessel density in mammary phyllodes tumors: A multicenter study of 185 cases
- Author
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Thomas C. Putti, Bonita K.B. Law, Fred Y.L. Kung, C. Soon Lee, Tai-shing Lau, Gary M.K. Tse, Richard A. Scolyer, Rooshdiya Z. Karim, and Philip C.W. Lui
- Subjects
Adult ,Vascular Endothelial Growth Factor A ,Pathology ,medicine.medical_specialty ,Stromal cell ,Angiogenesis ,Mammary gland ,Breast Neoplasms ,Biology ,Malignancy ,Pathology and Forensic Medicine ,chemistry.chemical_compound ,Phyllodes Tumor ,Biomarkers, Tumor ,medicine ,Humans ,Retrospective Studies ,Neovascularization, Pathologic ,Phyllodes tumor ,Epithelial Cells ,Middle Aged ,medicine.disease ,Immunohistochemistry ,Vascular endothelial growth factor ,Vascular endothelial growth factor A ,medicine.anatomical_structure ,chemistry ,Female ,Stromal Cells - Abstract
A retrospective review of 185 mammary phyllodes tumors (105 benign, 51 borderline, 29 malignant) from 4 centers was performed by immunohistochemistry to investigate the expression of vascular endothelial growth factor in the epithelial and stromal cells of mammary phyllodes tumors. The correlation of vascular endothelial growth factor with tumor grade, stromal cell nuclear pleomorphism, cellularity, mitotic rate, margin histomorphology, and the stromal microvessel density was evaluated. Vascular endothelial growth factor expression was found in the epithelium in 29% and in the stromal cells in 31% of cases. There was significant increase of vascular endothelial growth factor expression in the stromal cells with increasing degree of malignancy, but not the epithelium. Microvessel density in the stroma also showed significant correlation with tumor malignancy, and a correlation was shown with the stromal vascular endothelial growth factor expression. Statistical overlap of stromal vascular endothelial growth factor and microvessel density in predicting malignancy suggests that angiogenesis may be an effector mechanism for vascular endothelial growth factor. Assessment of stromal VEGF may be useful as an adjunctive diagnostic criterion in the histologic assessment of malignancy in phyllodes tumors.
- Published
- 2004
- Full Text
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6. Reliability of Scoring Arousals in Normal Children and Children with Obstructive Sleep Apnea Syndrome
- Author
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Patricia Galster, Tai Shing Lau, Carole L. Marcus, Tat Kong Wong, and Janita Lutz
- Subjects
Male ,medicine.medical_specialty ,Pediatrics ,Intraclass correlation ,Polysomnography ,Sleep, REM ,Validity ,Physiology (medical) ,medicine ,Humans ,Child ,Retrospective Studies ,Sleep Apnea, Obstructive ,medicine.diagnostic_test ,business.industry ,Reproducibility of Results ,Sleep apnea ,Electroencephalography ,Retrospective cohort study ,medicine.disease ,Confidence interval ,Obstructive sleep apnea ,El Niño ,Child, Preschool ,Physical therapy ,Female ,Neurology (clinical) ,Arousal ,business - Abstract
Study objectives Scoring of arousals in children is based on an extension of adult criteria, as defined by the American Sleep Disorders Association (ASDA). By this, a minimum duration of 3 seconds is required. A few recent studies utilized modified criteria for the study of children, with durations as short as 1 second. However, the validity and reliability of scoring these shorter arousals have never been verified. Based on studies in adults, we hypothesized that interscorer agreement for scoring arousals shorter than 3 seconds was poor. Design Retrospective review of polysomnograms by 2 experienced sleep practitioners who independently scored arousals according to the ASDA 3-second criteria and modified duration criteria of 1 and 2 seconds. Setting Academic hospital. Patients or participants 20 polysomnographic studies from children aged 3 to 8 years with mild to severe obstructive sleep apnea syndrome, and 16 polysomnographic studies from normal children. Interventions None. Measurements and results The intraclass correlation coefficient for scoring ASDA arousals was 0.90 (95% confidence interval: 0.81-0.95), indicating excellent interscorer agreement. The intraclass correlation coefficient for scoring modified 1-second and 2-second arousals were 0.35 (95% confidence interval: 0.02-0.61) and 0.42 (95% confidence interval: 0.12-0.65) respectively, indicating poor to fair interscorer agreement. Furthermore, modified 1-second and 2-second arousals accounted for less than 15% of all arousals scored. Conclusions We conclude that there is much poorer interscorer agreement for scoring arousals shorter than 3 seconds, when compared to the standard ASDA criteria. We propose that scoring of arousals in children should follow the standard ASDA criteria.
- Published
- 2004
- Full Text
- View/download PDF
7. Testing for homogeneity of relative differences under inverse sampling
- Author
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Ning-Zhong Shi, Jianhua Guo, Yanping Ma, and Tai Shing Lau
- Subjects
Statistics and Probability ,Score test ,Applied Mathematics ,Homogeneity (statistics) ,Monte Carlo method ,Negative binomial distribution ,Confidence interval ,Computational Mathematics ,Asymptotic power ,Computational Theory and Mathematics ,Test score ,Statistics ,Inverse sampling ,Mathematics - Abstract
A new homogeneity test of relative differences in K independent 2×2 tables arising from inverse sampling is proposed using score-based approach. Asymptotic power formula and confidence interval estimate for the common relative difference are also proposed. The methods are applied to a numerical example and a Monte Carlo simulation study is conducted to evaluate the performance of different tests with respect to size and power.
- Published
- 2004
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8. Impact of programmed second endoscopy with appropriate re-treatment on peptic ulcer re-bleeding: A systematic review
- Author
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K.H. Kwong, Dacita To-Ki Suen, S.P.Y. Kwok, Philip Wai Yan Chiu, and Tai-Shing Lau
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medicine.medical_specialty ,medicine.diagnostic_test ,Ulcer bleeding ,business.industry ,Peptic ,medicine.disease ,law.invention ,Endoscopy ,Surgery ,Re bleeding ,Randomized controlled trial ,law ,Peptic ulcer ,Recurrent bleeding ,Medicine ,In patient ,business - Abstract
Objectives: The aim of the present systematic review is to critically appraise the current evidence from published medical trials on the role of programmed second endoscopy with appropriate therapy on peptic ulcer re-bleeding. Methods: A systematic review of five prospective randomized controlled trials comparing the effect of programmed second endoscopy against conservative management on peptic ulcer re-bleeding was carried out. Results: From the meta-analysis of the combined results from the five trials on the effect of programmed second endoscopy in ulcer bleeding, we found that a programmed second endoscopy with appropriate therapy reduced the number of recurrent bleeding significantly (Peto odds ratio = 1.97, Mantel Haenszel-Peto P
- Published
- 2003
- Full Text
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9. Empirical Likelihood for Partially Linear Models
- Author
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Jian Shi and Tai-Shing Lau
- Subjects
Statistics and Probability ,partially linear model, empirical likelihood, nonparametric likelihood ratio, sieve approximation, weight functions ,Numerical Analysis ,Restricted maximum likelihood ,Linear model ,Nonparametric statistics ,Residual ,Likelihood principle ,Statistics::Computation ,Empirical likelihood ,Likelihood-ratio test ,Econometrics ,Statistics::Methodology ,Statistics, Probability and Uncertainty ,Likelihood function ,Mathematics - Abstract
In this paper, we consider the application of the empirical likelihood method to partially linear model. Unlike the usual cases, we first propose an approximation to the residual of the model to deal with the nonparametric part so that Owen's (1990) empirical likelihood approach can be applied. Then, under quite general conditions, we prove that the empirical log-likelihood ratio statistic is asymptotically chi-squared distributed. Therefore, the empirical likelihood confidence regions can be constructed accordingly.
- Published
- 2000
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10. Robust empirical likelihood for linear models under median constraints
- Author
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Jian Shi and Tai-shing Lau
- Subjects
Statistics and Probability ,Mathematical optimization ,Empirical likelihood ,General theory ,Robustness (computer science) ,Norm (mathematics) ,Statistics ,Linear model ,Likelihood function ,Smoothing ,Confidence interval ,Mathematics - Abstract
In this paper, we consider the application of the empirical likelihood for linear models under median constraints in view of robustness. For two simple median constraints, it is shown that conditions to ensure the consistency of the empirical likelihood confidence regions can be surprisingly relaxed compared with the normal approach under L norm. However, the coverage accuracy of the empirical likelihood confidence regions based on simple median constrains cannot be improved because of the discontinuity of the constraints. Therefore, a smoothed version of median constraint is proposed and a general theory is established to ensure its validity.
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- 1999
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11. Mixture models in hazard rates estimation
- Author
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Tai-shing Lau
- Subjects
Statistics and Probability ,Hazard (logic) ,Discrete time and continuous time ,Hazard ratio ,Statistics ,Applied mathematics ,Mixture model ,Computer Science::Databases ,Quotient ,Confidence interval ,Mixing (physics) ,Mathematics ,Exponential function - Abstract
We propose to use mixture of geometries to model the duration Ot a spell in discrete time. The discrete hazard rate can be determined by the moments of the mixing distribution through the qd(quotient difference) algorithm, By introducing a sequence of parameters called canonical moments, we can ensure the resulting estimate of the mixing distribution is supported on [0,1]. Using the bootstrap method, we can construct, instantaneous confidence intervals for the hazard rates. For the continuous time, a mixture of exponentials is proposed. By a simple transformation, the problem can be reduced to the case for mixture of geometries. The instantaneous confidence intervals for the hazard rates can be constructed.
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- 1998
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12. The latent class model for multiple binary screening tests
- Author
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Tai-Shing Lau
- Subjects
Statistics and Probability ,Distribution (mathematics) ,Screening test ,Binomial (polynomial) ,Epidemiology ,Statistics ,Binary number ,Sample (statistics) ,Gold standard (test) ,Sensitivity (control systems) ,Latent class model ,Mathematics - Abstract
Given multiple binary tests, such as repeated application of a blind screening test to each individual in a sample, we attemt to estimate the prevalence, sensitivity and specificity of the test without knowing the true disease status of those tested (gold standard). This problem is equivalent to finding the mixing distribution of a mixture of binomial distributions. We suggest a new method to determine the number of latent classes. Our simulations show that the coverage probabilities of the bootstrap confidence intervals of our estimates are correct. Our methods are illustrated by examples from published medical research. © 1997 John Wiley & Sons, Ltd.
- Published
- 1997
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13. The reliability of exchangeable binary systems
- Author
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Tai Shing Lau
- Subjects
Statistics and Probability ,Bernoulli's principle ,Applied mathematics ,Binary number ,Statistics, Probability and Uncertainty ,Arithmetic ,Reliability (statistics) ,Mathematics - Abstract
Assuming that the components of a system are Bernoulli and positive dependent by mixture, we can estimate the reliability of a k-out-of-n:F system, a consecutive k-out-of-n:F system and a circular consecutive k-out-of-n:F system by using canonical moments.
- Published
- 1992
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14. Radiation-induced meningiomas: experience at the Mount Sinai Hospital and review of the literature
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Robin J. Mitnick, Michael J. Harrison, Ved P. Sachdev, David E. Wolfe, and Tai-Shing Lau
- Subjects
Adult ,Male ,medicine.medical_specialty ,Neoplasms, Radiation-Induced ,medicine.medical_treatment ,Radiation Dosage ,Malignancy ,Meningioma ,Meningeal Neoplasms ,Humans ,Medicine ,Aged ,medicine.diagnostic_test ,business.industry ,Meninges ,Middle Aged ,medicine.disease ,Surgery ,Radiation therapy ,medicine.anatomical_structure ,Scalp ,Angiography ,Female ,Tinea capitis ,business ,Complication - Abstract
✓ From the records of The Mount Sinai Hospital, seven cases which met established criteria for radiation-induced meningiomas were identified. This represents the largest series of radiogenic meningiomas documented in North America and includes both intracranial and intraspinal tumors. The records and pathological specimens were reviewed and these data analyzed with other cases retrieved from the world literature. This study reveals that radiation-induced meningiomas can be categorized into three groups based on the amount of radiation administered: 1) low dose; 2) moderate dose and miscellaneous; and 3) high dose. The overwhelming majority of cases had received low-dose irradiation (800 rad) to the scalp for tinea capitis and the second largest group resulted from high-dose irradiation for primary brain tumors (> 2000 rad). The unique features distinguishing radiation-induced meningiomas from other meningiomas are reviewed. Although histologically atypical tumors were common in this series, overt malignancy was not encountered. The preoperative management of these lesions should include angiography to evaluate for large-vessel occlusive vasculopathy, a known association of meningiomas induced by high-dose irradiation. Given the propensity these tumors possess for recurrence, a wide bony and dural margin is recommended at surgical resection.
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- 1991
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15. Tumour angiogenesis and p53 protein expression in mammary phyllodes tumors
- Author
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C. Soon Lee, Richard A. Scolyer, Thomas C. Putti, Gary M.K. Tse, Tai-shing Lau, Fred Y.L. Kung, Philip C.W. Lui, and Bonita K.B. Law
- Subjects
Adult ,medicine.medical_specialty ,Pathology ,Stromal cell ,Adolescent ,Angiogenesis ,Breast Neoplasms ,Biology ,Malignancy ,Pathology and Forensic Medicine ,Neovascularization ,Surgical pathology ,Phyllodes Tumor ,medicine ,Humans ,Aged ,Cell Nucleus ,Neovascularization, Pathologic ,Microcirculation ,Anatomical pathology ,Middle Aged ,medicine.disease ,Immunohistochemistry ,Logistic Models ,Female ,medicine.symptom ,Stromal Cells ,Tumor Suppressor Protein p53 ,Hematopathology - Abstract
We examined 186 phyllodes tumors (106 benign, 51 borderline, 29 malignant) for angiogenesis by assessing stromal microvessel density by the hot spot method and assessing p53 protein expression; we correlated these factors with stromal cellularity, margin status, nuclear pleomorphism, mitosis, and stromal overgrowth. Increased degree of malignancy in phyllodes tumors is associated with increased patient age and tumor size. Microvessel density and p53 protein expression also showed a similar increase with malignancy. Using a logistic regression model, microvessel density was shown to be useful in predicting malignancy in phyllodes tumors, independent of key criteria of stromal overgrowth, nuclear pleomorphism, and mitosis. Microvessel density showed correlation with stromal cellularity and margin status, suggesting an interrelationship between these parameters. P53 protein expression showed a positive correlation with microvessel density, suggesting possible overlap in the underlying mechanism of these two factors in the pathogenesis of phyllodes tumors. The numbers of recurrences and metastases are small in our series, and no significant difference was demonstrated in microvessel density and p53 protein expression compared with the primary. We conclude that microvessel density and p53 are useful as independent criteria in evaluating malignancy in phyllodes tumors.
- Published
- 2003
16. Hormonal receptors expression in epithelial cells of mammary phyllodes tumors correlates with pathologic grade of the tumor: a multicenter study of 143 cases
- Author
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Fred Y.L. Kung, Bonita K.B. Law, Tai-shing Lau, Gary M.K. Tse, Richard A. Scolyer, Thomas C. Putti, and C. Soon Lee
- Subjects
Adult ,Pathology ,medicine.medical_specialty ,Receptors, Steroid ,Adolescent ,Mammary gland ,Estrogen receptor ,Breast Neoplasms ,Biology ,Phyllodes Tumor ,Progesterone receptor ,Carcinoma ,medicine ,Mitotic Index ,Humans ,Receptor ,Aged ,Phyllodes tumor ,Epithelial Cells ,General Medicine ,Middle Aged ,medicine.disease ,Immunohistochemistry ,Androgen receptor ,medicine.anatomical_structure ,Hormone receptor ,Female ,Neoplasm Recurrence, Local ,Stromal Cells - Abstract
We used immunohistochemical analysis to detect the presence of estrogen receptor (ER), progesterone receptor (PR), and androgen receptor (AR) protein expression in the epithelial and stromal cells of 143 phyllodes tumors (PTs). Expression of epithelial ER and PR proteins was common, occurring in 43% to 84% of PTs. Expression of epithelial AR protein and stromal ER, PR, and AR proteins was low (5% or less) in all tumors. An inverse relationship of epithelial ER and PR protein expression with degree of malignancy in PT was found (P < .05), and ER expression also correlated with mitotic count (P < .05). When considering PT with the expression of ER or PR proteins and the coexpression of both, the inverse relationship with tumor grade also was significant (P < .05). As the hormonal receptor protein expression shows a consistent decrease with increasing malignancy, we infer that the epithelium has a crucial role in the pathogenesis or progression of PT. Mammary phyllodes tumor (PT) is an uncommon stromal-epithelial neoplasm with a reported incidence of 0.3% to 0.5% of female breast tumors. 1-5 The median and mean ages of patients are 45 years, and the average tumor size is 4 to 5 cm. Rarely these lesions can occur in young or elderly women or in men. Pathologically, PTs are divided into benign, borderline, and malignant categories based on assessment of a combination of histologic features, namely mitotic count, cellularity and nuclear pleomorphism of the stromal cells, stromal overgrowth, and circumscription of the tumor border. 2,6 While borderline and malignant PTs can rarely metastasize, all PTs can recur locally. This propensity to recur makes proper and adequate treatment imperative, even in benign cases. Currently the mainstay of treatment of mammary PT remains surgical, and this also applies to recurrences and metastases. The expression of estrogen receptor (ER) and progesterone receptor (PR) in mammary neoplasms is well documented, particularly in carcinoma of the breast. The evaluation of hormonal receptors in breast carcinoma is useful as a predictor of response to endocrine manipulation therapy and as a prognostic index of the course of the disease. 7 While the usefulness of hormone receptor status of mammary PT is unknown, potentially this may offer similar therapeutic and prognostic information. We evaluated the expression of hormonal receptor proteins (ER, PR, and androgen receptor [AR]) in mammary PTs by immunohistochemical analysis with the aim of documenting the hormone receptor status of a large cohort of tumors from 3 centers in the Oceania region in an attempt to gain further insight into the pathobiology of these uncommon tumors.
- Published
- 2002
17. Deduction of paternity index from DNA mixture
- Author
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Karenda Fai Ngor Ngan, Xianghai Liao, Tai Shing Lau, and Jun Wang
- Subjects
Genetics ,Male ,Likelihood Functions ,Paternity Index ,Genotype ,Paternity ,DNA Fingerprinting ,Pathology and Forensic Medicine ,Vaginal tissue ,Phenotype ,DNA profiling ,Statistics ,Humans ,Female ,Law ,Mathematical Computing ,Forensic genetics ,Mathematics ,Probability - Abstract
Determination of individual genotypes in DNA mixture remains a challenge in forensic science. Using an approach of mixture of distributions, this article provides formula for calculation of paternity index (PI) in cases where only tissue mixture of the mother and alleged father, the genotypes of the mother and child, but not that of the alleged father are available. The formula has been used to solve a real case using mother's vaginal tissue contaminated with semen from alleged father.
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- 2002
18. Increased p53 protein expression in malignant mammary phyllodes tumors
- Author
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Gary M.K. Tse, Bonita K.B. Law, Tai-shing Lau, C. Soon Lee, Richard A. Scolyer, Thomas C. Putti, and Fred Y.L. Kung
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Adult ,Pathology ,medicine.medical_specialty ,Adolescent ,Age Factors ,Breast Neoplasms ,Gene mutation ,Biology ,Middle Aged ,Malignancy ,medicine.disease ,Prognosis ,Immunohistochemistry ,Pathology and Forensic Medicine ,Malignant transformation ,Staining ,Pleomorphism (cytology) ,Phyllodes Tumor ,Positive predicative value ,Statistical significance ,medicine ,Humans ,Neoplasm Recurrence, Local ,Tumor Suppressor Protein p53 - Abstract
The authors reviewed 143 cases (87 benign, 37 borderline, and 19 malignant) of mammary phyllodes tumors (PTs) and used immunohistochemistry to detect p53 protein product semi-quantitatively as negative, weak, moderate and strong (scored 0 to 3). For all PTs, an increasing trend of tumor size and malignancy was detected with increasing age. For p53 staining, 60 cases (42%) were negative, 55 (38%) stained weakly, 28 (13%) stained moderately, and 10 (7%) stained strongly. Of the 87 benign PTs, 41 (47%) were negative, 37 (43%) stained weakly, and 9 (10%) stained moderately. For the 37 borderline PTs, 16 (43%) were negative, 14 (38%) stained weakly, 6 (16%) stained moderately, and 1 (3%) stained strongly. Of the 19 malignant PTs, 3 (16%) were negative, 4 (21%) stained weakly, 3 (16%) stained moderately, and 9 (47%) stained strongly. The mean intensity score for p53 staining increased progressively from benign to borderline to malignant PT, with established statistical significance (P < .0001). This is significantly correlated with mitotic count but not stromal cellularity, pleomorphism, margin, and stromal overgrowth. When considering strong staining alone (score, 3), 47% of malignant, 3% of borderline, and none of the benign PTs were positive. The use of strong positive staining for diagnosing malignant PT gave positive and negative predictive values, specificity, and sensitivity of 90%, 92.5%, 99%, and 47%, respectively. Thus diffuse strong p53 protein staining can be used as a soft sign in assisting the diagnosis of malignant PT. Conversely, negative or weak staining of p53 protein in PT is of little discriminatory value. The role of p53 gene mutation in the malignant transformation of PT is unclear; but this may not be the sole mechanism as many malignant PT were p53 protein negative.
- Published
- 2002
19. On the heterogeneity of fecundability
- Author
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Tai-Shing Lau
- Subjects
Male ,Sequence ,Biometry ,Distribution (number theory) ,Applied Mathematics ,General Medicine ,Models, Biological ,Moment (mathematics) ,Standard error ,Fertility ,Pregnancy ,Data Interpretation, Statistical ,Infertility ,Statistics ,Bijection ,Applied mathematics ,Humans ,Female ,Life Tables ,Mixing (physics) ,Mathematics - Abstract
We propose to use a general mixing distribution in modeling the heterogeneity of the fecundability of couples. We introduce a sequence of parameters called canonical moments, which is in one to one correspondence with the moments, to characterize the mixing distribution. By using the bootstrap method, we can estimate the standard errors of our estimates. Our method modifies the usual moment estimates so that the resulting mixing distribution is always supported on [0, 1]. Moreover, the downward bias of the moment estimate of the number of support points would be reduced. Our approach can be used for censored data. The application of our technique in finding the sterile subpopulation is also discussed. The theory is illustrated with several data examples and simulations.
- Published
- 1996
20. On the heterogeneity of proportions
- Author
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Tai-Shing, Lau, primary
- Published
- 2000
- Full Text
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21. FOLKLORE-BASED LEARNING ON THE WEB-- PEDAGOGY, CASE STUDY, AND EVALUATION.
- Author
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Ho-Man Lee, Jimmy, Fong-Lok Lee, and Tai-Shing Lau
- Subjects
FOLKLORE ,LEARNING ,CHINESE people ,STUDENTS ,EDUCATION ,PSYCHOLOGY of learning ,LEARNING strategies - Abstract
Folklore-based learning is a kind of situated learning paradigm in which students learn by solving problems embedded in a near-real situation. The proposed learning approach employs further interesting story plots from folklores as the background situation to motivate students to participate in learning activities. It is believed that such a paradigm has, on one hand, the advantages of helping students to learn in an authentic situation and, on the other, the provision of interesting story episodes as a stimulating agent for less initiated students. This article reports a folklore-based learning system based on the well-known Chinese folklore called "Tong Pak Fu and Chou Heung," and its effects on learning the subject of probability by a group of 454 Hong Kong secondary school tsudents when compared with 3 teacher-guided methods. Results show that although no significant differences can be found among the different methods initially, when students with high pre-test scores were excluded the folklore-based learning group outperformed the other groups. Also, from student perception of the system it was found that the students prefer using this system to learn. Consider that no guidance on the subject matters was given to the students learning through this system, while students using the other methods were guided by experienced teachers, the results are very encouraging so that improvement and future developments to cover more topics are warranted. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
22. A note on D-optimal designs for models with and without an intercept.
- Author
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Kim-Hung Li, Tai-Shing Lau, and Congqi Zhang
- Subjects
REGRESSION analysis ,OPTIMAL designs (Statistics) ,MATHEMATICAL statistics ,STATISTICS ,ANALYSIS of variance ,EXPERIMENTAL design - Abstract
In this paper we give a sufficient condition under which the Z)-optimaI design for a regression model without an intercept can be obtained from the O-optimal design for the corresponding model with an intercept by simply removing the origin from its support points. Examples are given to demonstrate the applications of the results. [ABSTRACT FROM AUTHOR]
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- 2005
- Full Text
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23. Drug Treatment of Hypertension in the Elderly
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Daniel Pagano, Thomas C. Chalmers, Henry S. Sacks, Tai-Shing Lau, Joseph Lau, Dinah Reitman, and Jorge T. Insua
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Male ,medicine.medical_specialty ,medicine.drug_class ,Coronary Disease ,Severity of Illness Index ,law.invention ,Randomized controlled trial ,law ,Internal medicine ,Severity of illness ,Odds Ratio ,Internal Medicine ,medicine ,Humans ,Antihypertensive drug ,Stroke ,Aged ,Aged, 80 and over ,business.industry ,Mortality rate ,General Medicine ,Odds ratio ,Middle Aged ,medicine.disease ,Surgery ,Cerebrovascular Disorders ,Study heterogeneity ,Meta-analysis ,Hypertension ,Female ,business - Abstract
PURPOSE A meta-analysis of the effect of antihypertensive drug treatment on mortality and morbidity in elderly patients. DATA SOURCES A literature search of published articles from January 1980 to February 1992. STUDY SELECTION Randomized controlled trials of drug treatment of hypertension with end points for elderly patients reported separately. DATA EXTRACTION Mortality or morbidity end points or both in patients older than 59 years were pooled by determination of typical odds ratio. A meta-regression was used to study heterogeneity. RESULTS Nine major trials with 15,559 patients older than 59 years were identified. Death rates in the control group varied between 2.7% and 77.2%; stroke and coronary mortality increased with the severity-of-illness rank (P < 0.001). Overall, treated patients had an approximately 12% reduction in all-cause mortality (odds ratio, 0.88; 95% CI, 0.80 to 0.97; 953 events compared with 1069 events, P = 0.009). There was a 36% reduction in stroke mortality (odds ratio, 0.64; CI, 0.49 to 0.82; 94 events compared with 149 events, P < 0.001) and a 25% reduction in coronary heart disease mortality (odds ratio, 0.75; CI, 0.64 to 0.88; 263 events compared with 350 events, P < 0.001). Coronary morbidity was reduced 15% (odds ratio, 0.85; CI, 0.73 to 0.99; 325 events compared with 379 events, P = 0.036), and stroke morbidity was reduced 35% (odds ratio, 0.65; CI, 0.55 to 0.76; 247 events compared with 382 events, P < 0.001). CONCLUSION Overall, treatment of hypertension in elderly patients produces a significant benefit in total mortality and cardiovascular morbidity and mortality. However, this benefit may be reduced in the oldest age groups.
- Published
- 1994
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24. Systematic review Impact of programmed second endoscopy with appropriate re-treatment on peptic ulcer re-bleeding: A systematic review.
- Author
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Chiu, Philip Wai-Yan, Tai-Shing Lau, Kwok-Hung Kwong, Philip Wai-Yan, Suen, Dacita To-Ki, and Kwok, Samuel Po-Yin
- Subjects
- *
PEPTIC ulcer , *ULCER treatment , *ENDOSCOPY - Abstract
The aim of the present systematic review is to critically appraise the current evidence from published medical trials on the role of programmed second endoscopy with appropriate therapy on peptic ulcer re-bleeding. A systematic review of five prospective randomized controlled trials comparing the effect of programmed second endoscopy against conservative management on peptic ulcer re-bleeding was carried out. From the meta-analysis of the combined results from the five trials on the effect of programmed second endoscopy in ulcer bleeding, we found that a programmed second endoscopy with appropriate therapy reduced the number of recurrent bleeding significantly (Peto odds ratio = 1.97, Mantel Haenszel-Peto P < 0.01). The number of patients needed for treatment with a programmed second endoscopy in order to prevent one recurrent bleeding ranged from four to 11. Programmed second endoscopy with appropriate therapy reduced the number of recurrent bleeding significantly in patients with bleeding peptic ulcers. Individual trials also showed a possible benefit in reduction of the number of surgical interventions. [ABSTRACT FROM AUTHOR]
- Published
- 2003
- Full Text
- View/download PDF
25. Tumour Angiogenesis and p53 Protein Expression in Mammary Phyllodes Tumors.
- Author
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Tse, Gary M.K., Lui, Philip C.W., Scolyer, Richard A., Putti, Thomas C., Bd, Dip. Am., Kung, Fred Y.L., Law, Bonita K.B ., Tai Shing Lau, and C. Soon Lee
- Published
- 2003
- Full Text
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26. Higher-Order Kappa-Type Statistics for a Dichotomous Attribute in Multiple Ratings
- Author
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Tai-Shing Lau
- Subjects
Statistics and Probability ,Sequence ,Models, Statistical ,General Immunology and Microbiology ,Applied Mathematics ,Binary number ,Blood Pressure ,General Medicine ,General Biochemistry, Genetics and Molecular Biology ,Moment (mathematics) ,Inter-rater reliability ,Cohen's kappa ,Research Design ,Hypertension ,Statistics ,Binary data ,Humans ,Order (group theory) ,General Agricultural and Biological Sciences ,Mathematics ,Kappa ,Probability - Abstract
We introduce a sequence of parameters called canonical moments to characterize the predictive value of the pattern of consensus among (kappa-1) ratings to an additional rating. The usual kappa coefficient of agreement among ratings (two or more) is just the second canonical moment. By using the higher canonical moments, we can evaluate the consensus of multiple binary ratings.
- Published
- 1993
- Full Text
- View/download PDF
27. On Dependent Repeated Screening Tests
- Author
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Tai-Shing Lau
- Subjects
Statistics and Probability ,General Immunology and Microbiology ,Screening test ,Applied Mathematics ,Statistics ,General Medicine ,Sensitivity (control systems) ,General Agricultural and Biological Sciences ,General Biochemistry, Genetics and Molecular Biology ,Mathematics ,Statistical hypothesis testing ,Test (assessment) - Abstract
A screening test is applied n times to a person with known true status. If more than k tests have positive outcomes, then the person is assigned to be screen-positive; otherwise, the person is assigned to be screen-negative. Assuming that the tests are exchangeable, we can characterize the possible dependence among tests by at most n parameters called canonical moments, which can be estimated from the data. The performance characteristics of the composite test (such as likelihood ratios, sensitivity, and specificity) can be computed based on these estimates. Thus, we can choose n and k so that the desired levels of likelihood ratios, sensitivity, and specificity can be achieved. We study the cases n = 2 and n = 3 in detail.
- Published
- 1991
- Full Text
- View/download PDF
28. Drug treatment of hypertension in the elderly: a meta-analysis.
- Author
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Insua, Jorge T., Sacks, Henry S., Tai-Shing Lau, Lau, Joseph, Reitman, Dinah, Pagano, Daniel, Chalmers, Thomsa C., Insua, J T, Sacks, H S, Lau, T S, Lau, J, Reitman, D, Pagano, D, and Chalmers, T C
- Subjects
MEDICAL care for older people ,DRUG efficacy ,HYPERTENSION ,THERAPEUTICS ,CEREBROVASCULAR disease ,COMPARATIVE studies ,CORONARY disease ,RESEARCH methodology ,MEDICAL cooperation ,META-analysis ,RESEARCH ,EVALUATION research ,SEVERITY of illness index ,ODDS ratio ,DISEASE complications - Abstract
Purpose: A meta-analysis of the effect of antihypertensive drug treatment on mortality and morbidity in elderly patients.Data Sources: A literature search of published articles from January 1980 to February 1992.Study Selection: Randomized controlled trials of drug treatment of hypertension with end points for elderly patients reported separately.Data Extraction: Mortality or morbidity end points or both in patients older than 59 years were pooled by determination of typical odds ratio. A meta-regression was used to study heterogeneity.Results: Nine major trials with 15,559 patients older than 59 years were identified. Death rates in the control group varied between 2.7% and 77.2%; stroke and coronary mortality increased with the severity-of-illness rank (P < 0.001). Overall, treated patients had an approximately 12% reduction in all-cause mortality (odds ratio, 0.88; 95% CI, 0.80 to 0.97; 953 events compared with 1069 events, P = 0.009). There was a 36% reduction in stroke mortality (odds ratio, 0.64; CI, 0.49 to 0.82; 94 events compared with 149 events, P < 0.001) and a 25% reduction in coronary heart disease mortality (odds ratio, 0.75; CI, 0.64 to 0.88; 263 events compared with 350 events, P < 0.001). Coronary morbidity was reduced 15% (odds ratio, 0.85; CI, 0.73 to 0.99; 325 events compared with 379 events, P = 0.036), and stroke morbidity was reduced 35% (odds ratio, 0.65; CI, 0.55 to 0.76; 247 events compared with 382 events, P < 0.001).Conclusion: Overall, treatment of hypertension in elderly patients produces a significant benefit in total mortality and cardiovascular morbidity and mortality. However, this benefit may be reduced in the oldest age groups. [ABSTRACT FROM AUTHOR]- Published
- 1994
- Full Text
- View/download PDF
29. On an extremal problem of Fejér
- Author
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Tai-Shing Lau and W. J. Studden
- Subjects
Mathematics(all) ,Numerical Analysis ,General Mathematics ,Applied Mathematics ,Orthogonal polynomials ,Calculus ,Applied mathematics ,Function minimization ,Analysis ,Mathematics ,Interpolation - Published
- 1988
- Full Text
- View/download PDF
30. Moment inequalities
- Author
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Tai-shing Lau
- Subjects
Statistics and Probability ,Statistics, Probability and Uncertainty - Published
- 1989
- Full Text
- View/download PDF
31. D-optimal designs on the unit q-ball
- Author
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Tai-Shing Lau
- Subjects
Statistics and Probability ,Optimal design ,Discrete mathematics ,Polynomial regression ,Mathematical optimization ,Polynomial ,Applied Mathematics ,Regression analysis ,D optimal ,symbols.namesake ,Q-ball ,symbols ,Statistics, Probability and Uncertainty ,Fisher information ,Unit (ring theory) ,Mathematics - Abstract
Consider a polynomial regression model on the unit q-ball. We can express the determinant of the information matrix in terms of canonical moments. Thus we can find the robust-type D-optimal designs in the sense of Stigler (1971) and Studden (1982). We also consider the D-optimal design for some special multi-response regression models where each response is a polynomial.
- Published
- 1988
- Full Text
- View/download PDF
32. Optimal Designs for Trigonometric and Polynomial Regression Using Canonical Moments
- Author
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Tai-Shing Lau and W. J. Studden
- Subjects
Statistics and Probability ,Optimal design ,Polynomial regression ,Mathematical optimization ,Degree (graph theory) ,Type (model theory) ,Regression ,62J05 ,canonical moments ,62K05 ,Order (group theory) ,Applied mathematics ,trig regression ,Statistics, Probability and Uncertainty ,Trigonometry ,Optimal designs ,Mathematics - Abstract
Consider a trigonometric regression of order $m$ or a polynomial regression of degree $m$. Explicit $D_s$-optimal designs are given for some subsets of the coefficients. Lauter type optimal designs are given for various models involving the order or the degree. The designs are calculated using canonical moments.
- Published
- 1985
33. On Repeated Screening Tests
- Author
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Tai Shing Lau
- Subjects
Statistics and Probability ,General Immunology and Microbiology ,Screening test ,Applied Mathematics ,Statistics ,Polytomous Rasch model ,General Medicine ,General Agricultural and Biological Sciences ,General Biochemistry, Genetics and Molecular Biology ,Test (assessment) - Abstract
We point out the connection between quality control and repeated screening tests, and suggest a practical way to design the repeated screening tests so that the composite test achieves the desired level of sensitivity and specificity. We further point out the benefits of using likelihood ratios to measure the performance of a screening test. Then we investigate repeated tests when we have polytomous disease levels and polytomous diagnostic levels.
- Published
- 1989
- Full Text
- View/download PDF
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