Game theoretic power aware wireless data access

The paper examines the following wireless data access scenario: a number of clients are interested in a set of data items kept at the server. A client sends a query request to inform the server of its desired data item. The server replies in the common broadcast channel. We first define a utility function that considers the client's power consumption in transmit, receive and idle modes. Specifically, utility is expressed as the number of queries that can be completed given a fixed energy source. Based on the utility function, we formulate our power aware wireless data access scheme as a non-cooperative game, called the WDA game. From our theoretical analysis, we show that clients are not always necessary to send query requests to the server. Instead, each client determines the request probability without any explicit communication with one another. Furthermore, we design and evaluate the server and client algorithms for the WDA game. Simulation results confirm that our proposed scheme, compared with a simple always-request one, increases the utility and lifetime of every client while reducing the number of requests sent, at the cost of a slightly larger average query delay.published_or_final_versio

Patients with Helicobacter pylori positive and negative duodenal ulcers have distinct clinical characteristics

Aim: To assess the clinical characteristics of Helicobacter pylori (H pylori) negative duodenal ulcer. Methods: Patients with an endoscopic diagnosis of duodenal ulcer between 1996 and 2002 were included in the present study. Patients were considered to be negative for H pylori, if both histological examination and rapid urease test of biopsy specimens were negative. A comparison was made between patients with H pylori positive and negative duodenal ulcers. Results: A total of 1 343 patients were studied. Their mean age was 54.7±0.5 years. There was a male preponderance (M:F = 2.5:1). Three hundred and ninety-eight patients (29.6%) did not have H pylori infection. The annual proportion of patients with H pylori negative duodenal ulcers increased progressively from 1996 to 2002. On multivariate analysis, patients with H pylori negative duodenal ulcer were more likely to be older, have concomitant medical problem, pre-existing malignancy, recent surgery, underlying sepsis, or taken non-steroidal anti-inflammatory drugs. In terms of clinical presentations, patients with H pylori negative duodenal ulcer were more likely to present with bleeding, multiple ulcers and larger ulcers. Conclusion: The proportion of patients with H pylori negative duodenal ulcers is on the rise because of a continued drop in incidence of H pylori positive duodenal ulcers in recent years. Such patients have distinct clinical characteristics and it is important to ascertain the H pylori status before starting eradication therapy. © 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio

Piezoelectric dispenser based on a piezoelectric-metal-cavity actuator

Author name used in this publication: K. H. LamAuthor name used in this publication: C. L. SunAuthor name used in this publication: K. W. KwokAuthor name used in this publication: H. L. W. Chan2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Lead-free piezoelectric-metal-cavity (PMC) actuators

2008-2009 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Spontaneous pneumomediastinum in a scuba diver

Pneumomediastinum usually occurs following an airleak from the lungs, or from a perforated oesophagus. We report on a 30-year-old man who developed pneumomediastinum after scuba diving. The patient presented with acute onset of throat pain, odynophagia, and hoarseness of voice. The literature is reviewed for this condition.published_or_final_versio

GPU-based proximity query processing on unstructured triangular mesh model

This paper presents a novel proximity query (PQ) approach capable to detect the collision and calculate the minimal Euclidean distance between two non-convex objects in 3D, namely the robot and the environment. Such approaches are often considered as computationally demanding problems, but are of importance to many applications such as online simulation of haptic feedback and robot collision-free trajectory. Our approach enables to preserve the representation of unstructured environment in the form of triangular meshes. The proposed PQ algorithm is computationally parallel so that it can be effectively implemented on graphics processing units (GPUs). A GPU-based computation scheme is also developed and customized, which shows >200 times faster than an optimized CPU with single core. Comprehensive validation is also conducted on two simulated scenarios in order to demonstrate the practical values of its potential application in image-guided surgical robotics and humanoid robotic control.published_or_final_versio

A study on the disk-shaped piezoelectric transformer with multiple outputs

Author name used in this publication: K. H. LamAuthor name used in this publication: S. WangAuthor name used in this publication: K. W. KwokAuthor name used in this publication: X. Z. Zhao2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Oesophageal cancer located above the tracheal bifurcation is an independent poor prognostic factor. Neoadjuvant chemoradiation improves survival

published_or_final_versio

香港及珠三角地区MODIS高分辨率气溶胶光学厚度的反演

Author name used in this publication: 黄文声Author name used in this publication: NICHOL JanetAuthor name used in this publication: 李权镐Author name used in this publication: 郭嘉熙Title in Traditional Chinese: 香港及珠三角地區MODIS高分辨率氣溶膠光學厚度的反演Journal title in Traditional Chinese: 環境科學學報2008-2009 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Energy harvesting with piezoelectric drum transducer

Author name used in this publication: Kwok Ho LamAuthor name used in this publication: Cheng Liang SunAuthor name used in this publication: Kin Wing KwokAuthor name used in this publication: Helen Lai Wa ChanAuthor name used in this publication: Ming Sen GuoAuthor name used in this publication: Xing-Zhong Zhao2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe