Periodic solutions of a derivative nonlinear Schrödinger equation: Elliptic integrals of the third kind

International Conference on Engineering and Computational Mathematics, The Hong Kong Polytechnic University, Hong Kong, 27–29 May 2009The nonlinear Schrödinger equation (NLSE) is an important model for wave packet dynamics in hydrodynamics, optics, plasma physics and many other physical disciplines. The 'derivative' NLSE family usually arises when further nonlinear effects must be incorporated. The periodic solutions of one such member, the Chen-Lee-Liu equation, are studied. More precisely, the complex envelope is separated into the absolute value and the phase. The absolute value is solved in terms of a polynomial in elliptic functions while the phase is expressed in terms of elliptic integrals of the third kind. The exact periodicity condition will imply that only a countable set of elliptic function moduli is allowed. This feature contrasts sharply with other periodic solutions of envelope equations, where a continuous range of elliptic function moduli is permitted. © 2011 Elsevier B.V. All rights reserved.postprin

The Hong Kong Telephone Directory Enquiry System

Concerns the design and performance of the telephone directory enquiry system that has been newly adopted in Hong Kong. This system maintains three million telephone records and supports over 40,000 enquiries per hour at the peak. In Hong Kong society, the uses of English and Chinese (in particular, Cantonese) has been blending in a thrust of exciting language culture, giving rise to a variety of telephone enquires that traditional B-tree or hashing-based telephone directory enquiry systems fail to handle. The efficiency and flexibility achieved by the new system stem from hosting all indexing data structures in the main memory; these data structures occupy about half a giga-byte and would have been considered too expensive to be placed in main memory in the past.published_or_final_versio

Polyethylene woven fabric reinforced dentures - properties and construction

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Logistic regression modeling of construction negotiation outcomes

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Bond strengths of alginate adhesive

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Do dry-heat cured dentures fit better?

Abstract no. 69published_or_final_versio

Acrylic resin reinforced with high performance polyethylene fiber

Abstract no. 1269published_or_final_versio

Imaging modalities for preoperative assessment in dental implant therapy: an overview

Preoperative assessment of patients for dental implant therapy often requires extensiveradiographic examination. Many imaging modalities have been reported to be usefulincluding periapical, panoramic, lateral cephalometric and tomographic radiography,computed tomography, interactive computed tomography, and magnetic resonanceimaging. This paper reviews various imaging techniques, their applications and limitationsin dental implant treatment planning.published_or_final_versio

Does timing of surgery matter in fragility hip fractures?

The effect of delay of surgery on the geriatric hip fractures has been a subject of interest in the past two decades. While the elderly patients will not tolerate long periods of immobilization, it is still unclear how soon these surgeries need to be performed. A review of existing literature was performed to examine the effect of timing of surgery on the different outcome parameters of these patients. Although there is conflicting evidence that early surgery would improve mortality, there is widespread evidence in the literature that other outcomes including morbidity, the incidence of pressure sores, and the length of hospital stay could be improved by shortening the waiting time of hip fracture surgery. We concluded that it is beneficial to the elderly patients to receive surgical treatment as an urgent procedure as soon as the body meets the basic anesthetic requirements. © 2010 The Author(s).published_or_final_versionSpringer Open Choice, 21 Feb 201

Prevalence of malnutrition and risk factors in geriatric patients of a convalescent and rehabilitation hospital

Objectives. To investigate the prevalence and risk factors of malnutrition in geriatric patients admitted to a convalescent and rehabilitation hospital. Design. Cross-sectional study. Setting. Regional hospital, Hong Kong. Patients. A total of 120 patients (aged 60 years or older) referred to Tung Wah Eastern Hospital. Main outcome measures. Anthropometric, biochemical, and haematological parameters were measured for nutritional assessment. Malnutrition was defined as a body mass index of lower than 18.5 kg/m2 and serum albumin level of lower than 35 g/L. The clinical outcomes of patients were also recorded. The predictive value of the Chinese Mini Nutritional Assessment as a nutritional screening tool was assessed. Potential risk factors associated with malnutrition were evaluated according to established protocols. Results. The mean age of patients was 80.3 years (standard deviation, 7.4 years), and the mean body mass index was 21.9 kg/m2 (standard deviation, 4.4 kg/m2). The prevalence of malnutrition was 16.7%. The age distribution of malnourished patients (mean, 86.2 years; standard deviation, 7.0 years; n=20) was significantly different to those nourished (mean, 79.1 years; standard deviation, 6.9 years; n=100) [P=0.0001]. Mortality was also higher in malnourished patients (25%) than nourished patients (4%) [P=0.001]. Based on the Chinese Mini Nutritional Assessment, 16.9% of patients were classified as malnourished (cut-off value, 18.5). The Chinese Mini Nutritional Assessment was useful as a screening tool to exclude patients who were not malnourished, ie it had a high negative predictive value (95%). Being totally dependent for the performance of activities of daily living, living in a home for the elderly, and being chair- or bed-bound posed a significantly increased risk of malnutrition. The presence of mental depression (geriatric depression scale score of 8 or higher), moderately or severely impaired cognitive function (abbreviated mental test score of lower than 7), or polypharmacy (five medications or more) did not significantly affect risk of malnutrition. Conclusions. Malnutrition was common in the geriatric patients studied and was associated with an increased mortality. The Chinese Mini Nutritional Assessment was a useful screening tool to exclude malnutrition. Significant risk factors of malnutrition were total dependence, living in a home for the elderly, and being chair- or bed-bound.published_or_final_versio