Maximal disk based histogram for shape retrieval

2002-2003 > Academic research: refereed > Refereed conference paperVersion of RecordPublishe

Visibility-based coverage of mobile sensors in non-convex domains

The area coverage problem of mobile sensor networks has attracted much attention recently, as mobile sensors find many important applications in remote and hostile environments. However, the deployment of mobile sensors in a non-convex domain is nontrivial due to the more general shape of the domain and the attenuation of sensing capabilities caused by the boundary walls or obstacles. We consider the problem of exploration and coverage by mobile sensors in an unknown non-convex domain. We propose the definition of 'visibility-based Voronoi diagram' and extend the continuous-time Lloyd's method, which only works for convex domains, to deploy the mobile sensors in the unknown environments in a distributed manner. Our simulations show the effectiveness of the proposed algorithms. © 2011 IEEE.published_or_final_versionThe 8th International Symposium on Voronoi Diagrams in Science and Engineering (ISVD2011), Qingdao, China, 28-30 June 2011. In Proceedings of the 8th ISVD, 2011, p. 105-11

Planar hexagonal meshing for architecture

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CVT-based 2D motion planning with maximal clearance

Maximal clearance is an important property that is highly desirable in multi-agent motion planning. However, it is also inherently difficult to attain. We propose a novel approach to achieve maximal clearance by exploiting the ability of evenly distributing a set of points by a centroidal Voronoi tessellation (CVT). We adapt the CVT framework to multi-agent motion planning by adding an extra time dimension and optimize the trajectories of the agents in the augmented domain. As an optimization framework, our method can work naturally on complex regions. We demonstrate the effectiveness of our algorithm in achieving maximal clearance in motion planning with some examples.published_or_final_versionThe 2011 IEEE International Conference on Robotics and Automation (ICRA), Shanghai, China, 9-13 May 2011. In Proceedings of the IEEE-ICRA, 2011, p. 2281-228

Generalized self-driven AC-DC synchronous rectification techniques for single- and multiphase systems

This paper extends the single-phase self-driven synchronous rectification (SDSR) technique to multiphase ac-dc systems. Power MOSFETs with either voltage- or current-sensing self-driven gate drives are used to replace the diodes in the rectifier circuits. The generalized methodology allows multiphase SDSRs to be designed to replace the multiphase diode rectifiers. Unlike the traditional SR that is designed for high-frequency power converters, the SDSR proposed here can be a direct replacement of the power diode bridges for both low- and high-frequency operations. The SDSR utilizes its output dc voltage to supply power to its control circuit. No start-up control is needed because the body diodes of the power MOSFETs provide the diode rectifier for the initial start-up stage. The generalized method is demonstrated in 2-kW one-phase and three-phase SDSRs for inductive, capacitive, and resistive loads. Power loss reduction in the range of 50%-69% has been achieved for the resistive load. © 2009 IEEE.published_or_final_versio

VISJET & VISFLOOD: Software for environment hydraulic modeling & visualization

We present two general interactive PC-based modeling and visualization software systems developed for the study of two types of environmental water flows: buoyant jet mixing and urban drainage problems. VISJET (http://www.aoe-water.hku.hk/visjet) is arguably the most robust software with advanced graphics for the prediction of mixing and transport of effluent discharges into a stratified crossflow. The prediction engine is a Lagrangian model for buoyant jets with three-dimensional trajectories, and is based on extensive basic experiments and turbulence model calculations. It can be used in outfall design and environmental impact assessment, and as an educational or training tool. VISFLOOD (http://www.aoe-water.hku.hk/visflood) is based on the numerical solution of the Saint-Venant equations, and caters for the simulation of unsteady flood propagation in urban drainage systems. Both software systems are fully interactive with data interrogation; the 3D visualization is fully integrated with the model engine, and enables the user to appreciate the context of the problem in a most effective way. Both models have been well-validated against laboratory and field data, and have been applied to many actual engineering projects. This software product is an outcome of a grant by the Hong Kong Innovation and Technology Fund (ITF).published_or_final_versio

Smoking and non-neoplastic lung disease in Canadian men and women

MAIN OBJECTIVE: To document and assess the current health impact of non-neoplastic lung disease (NNLD) in Canadian men and women that is attributable to smoking. DESIGN: Comparison of three recent studies providing estimates of smoking-attributable deaths, potential years of life lost, hospital separations and hospital days due to NNLD in Canada. Review of recent epidemiological studies providing relative risk estimates of smoking-attributable mortality and morbidity for chronic obstructive pulmonary disease and pneumonia, including a meta-analysis. MAIN RESULTS: Each year at least 6700 Canadian men and women die from NNLD attributable to smoking. Smoking-attributable NNLD deaths in men outnumber those in women by about 2 to 1. The majority of these deaths are due to chronic obstructive pulmonary disease, which is exceeded in importance as a smoking-attributable cause of death only by lung cancer and ischemic heart disease. NNLD accounts for about 20% of all smokingattributable deaths in Canada, 14% of the potential years of life lost due to smoking, and 22% and 25% of all smokingattributable hospital separations and hospital days, respectively. Long term follow-up assessments of large cohorts suggest that the impact of smoking on health has been underestimated. Recent studies also suggest that women may be more susceptible than men to the adverse effects of smoking on lung function. CONCLUSION: NNLD caused by smoking has an important health impact in Canada. Tobacco control strategies must be enhanced. Key Words: Lung diseases, Morbidity, Mortality, Smoking Le tabagisme et la maladie pulmonaire non cancéreuse chez les Canadiens et Canadiennes OBJECTIF PRINCIPAL : Documenter et évaluer les influences actuelles sur la santé de la maladie pulmonaire non cancéreuse chez des Canadiens et Canadiennes, et qui sont imputables au tabagisme. MODÈLE : Comparaison de trois études récentes fournissant des estimés des décès attribuables au tabagisme, des années potentielles de vie perdues, des congés donnés aux patients hospitalisés et des journées d'hospitalisation dus à la maladie pulmonaire non cancéreuse au Canada. Revue des études épidémiologiques récen-tes fournissant des estimés du risque relatif de la mortalité attribuable au tabagisme et de la morbidité liée à la maladie pulmonaire obstructive chronique et à la pneumonie, incluant une méta-analyse. voir page suivante I t is now well established that smoking is the most important preventable cause of premature mortality and morbidity in Canadian men and women (1,2), as it is in the populations of other developed countries (3,4). At least 33,000 Canadians die each year as a result of tobacco use, which also accounts for more than 200,000 hospital separations, three million hospital days and some $9.5 billion in costs from lost productivity and direct health care expenditures (2). Despite this enormous health toll, smoking remains prevalent. Estimates from the National Population Health Survey conducted in 1994 indicate that 6.9 million Canadians, 31% of the population aged 15 years and over, smoke (5). Further, rates of smoking among young Canadians, after some years of decline, have now plateaued (6) and may actually be increasing in some provinces, notably in Ontario The primary purpose of this paper is to document and assess current estimates of the health impact of smoking in Canada with regard to non-neoplastic lung disease (NNLD) and to point out some limitations of these data. As well, recent reports concerning long term epidemiological studies of the relationship of smoking to NNLD are reviewed, including a meta-analysis of relative risk estimates. Attention is drawn to recent studies that indicate the possibility that the lungs of women may be particularly susceptible to the adverse effects of tobacco smoke. HEALTH IMPACT OF SMOKING DUE TO NNLD Smoking-attributable mortality: Three studies provide estimates of the current mortality impact of tobacco use in Canadian men and women Makomaski Illing and Kaiserman (1), using risk estimates from the same source, concluded that in 1991 there were more than 8100 NNLD deaths among Canadians attributable to smoking, out of a total of 41,408 smoking-attributable deaths. Most recently, Single et al (2) used mortality estimates derived from a meta-analysis of epidemiological studies conducted by English et al (10), discussed further below. They concluded that in 1992 NNLD deaths in Canadians attributable to smoking exceeded 6700, out of a total estimate of more than 33,000 smoking-attributable deaths. In all three estimates shown in Comparability of the mortality estimates: Because the RISKS OF NNLD MORTALITY AND MORBIDITY ASSOCIATED WITH SMOKING Mortality: A study by Canadian investigators was among the first to document the excess risk of mortality from NNLD in smokers compared with nonsmokers (11,12). In the final six-year follow-up study of some 78,000 male veterans, initiated in 1955 by the Department of National Health and Welfare (12), it was found that veterans with a lifetime history of smoking cigarettes had about 11 and eight times the risk of mortality from chronic bronchitis and emphysema, respectively, compared with nonsmokers. A dose-response relationship between the amount smoked daily and the risk of mortality was also observed. For pneumonia and influenza there was a small increase in relative risk (1.4). Since then, a host of epidemiological studies from many countries have confirmed the causal relationship between smoking and COPD in both men and women, as well as a small increase in the risk of mortality from pneumonia (13-17). Doll et al Doll et al Recently, Gold et al (27), in a study of the effects of cigarette smoking on the level and rate of growth of pulmonary function in large cohorts of adolescent boys and girls, demonstrated that the growth of lung function in association with smoking was more severely affected in the girls. This finding is particularly worrisome in the context of the ages at which adolescent girls and boys begin to smoke. In the 1994 Canadian Youth Smoking Survey (6) it was found that although the rates of beginning to smoke were similar in boys and girls ages 10 to 12 years (4% in each), by ages 13 to 14 years this rate was significantly higher than girls (15%) compared with boys (9%). Girls may not only be more susceptible to the adverse effects of smoking, but they appear to be getting a 'head start' on this addiction. While sex differences in susceptibility to the smokinginduced changes in lung function require more study, particularly with regard to underlying biological mechanisms, the primal importance of smoking cessation in reducing the age-related decline in FEV 1 in smokers with mild obstructive pulmonary disease is beyond disput

Concomitant CIS on TURBT does not impact oncological outcomes in patients treated with neoadjuvant or induction chemotherapy followed by radical cystectomy

© Springer-Verlag GmbH Germany, part of Springer Nature 2018Background: Cisplatin-based neoadjuvant chemotherapy (NAC) for muscle invasive bladder cancer improves all-cause and cancer specific survival. We aimed to evaluate whether the detection of carcinoma in situ (CIS) at the time of initial transurethral resection of bladder tumor (TURBT) has an oncological impact on the response to NAC prior to radical cystectomy. Patients and methods: Patients were identified retrospectively from 19 centers who received at least three cycles of NAC or induction chemotherapy for cT2-T4aN0-3M0 urothelial carcinoma of the bladder followed by radical cystectomy between 2000 and 2013. The primary and secondary outcomes were pathological response and overall survival, respectively. Multivariable analysis was performed to determine the independent predictive value of CIS on these outcomes. Results: Of 1213 patients included in the analysis, 21.8% had concomitant CIS. Baseline clinical and pathologic characteristics of the ‘CIS’ versus ‘no-CIS’ groups were similar. The pathological response did not differ between the two arms when response was defined as pT0N0 (17.9% with CIS vs 21.9% without CIS; p = 0.16) which may indicate that patients with CIS may be less sensitive to NAC or ≤ pT1N0 (42.8% with CIS vs 37.8% without CIS; p = 0.15). On Cox regression model for overall survival for the cN0 cohort, the presence of CIS was not associated with survival (HR 0.86 (95% CI 0.63–1.18; p = 0.35). The presence of LVI (HR 1.41, 95% CI 1.01–1.96; p = 0.04), hydronephrosis (HR 1.63, 95% CI 1.23–2.16; p = 0.001) and use of chemotherapy other than ddMVAC (HR 0.57, 95% CI 0.34–0.94; p = 0.03) were associated with shorter overall survival. For the whole cohort, the presence of CIS was also not associated with survival (HR 1.05 (95% CI 0.82–1.35; p = 0.70). Conclusion: In this multicenter, real-world cohort, CIS status at TURBT did not affect pathologic response to neoadjuvant or induction chemotherapy. This study is limited by its retrospective nature as well as variability in chemotherapy regimens and surveillance regimens.Peer reviewedFinal Accepted Versio