A decentralized control framework for modular robots

Distributed control paradigm offers robustness, scalability, and simplicity to the control and organization of module based systems. MSR (Modular Self-Reconfigurable) robot is a class of robot that best demonstrate the effectiveness of distributed systems as all modules in the robot are individuals that perform their own actuation and computation; the behavior of the complete robot is a collective behavior of all independent modules. In this paper, a general control framework, named General Suppression Framework, is proposed and a distributed control system based on the framework is presented. The control system is designed to control a set of MSR robots configured into a planar manipulator arm. All modules in the manipulator arm contain their own processing and actuation units, which allow them to evaluate and react to the environment independently. The modules can perform passive communication with their immediate neighbors and can exhibit aggressive or tolerant behavior based on the environment change to generate emergent group behaviors. A simulation program is developed to demonstrate the effectiveness of the distributed system in controlling the module based planar manipulator arm.published_or_final_versio

Topological representation and analysis method for multi-port and multi-orientation docking modular robots

For MSR Robots to successfully configure from one configuration into another, the control system must be able to visualize the current structure of the robot, which cannot be done without appropriate information about each module's docking status. Although the type of information required to visualize the structure of a MSR robot differs with the physical design of the modules, there are essential information that are commonly required, such as docking orientation and identity of neighboring modules. This paper presents a novel multi-port and multi-orientation modular robot, and a representation method that can uniquely represent the geometric structure of a group of connected modules and to analyze the number of "reconfigurable DOF" within the structure. The proposed method uses labeled planar graphs and incidence matrices to describe the docking status of the modules within the structure, which helps to effectively encode the data in computer understandable expressions. In addition to the work in configuration analysis, an innovative mechanism for detecting the orientation of each docking port is also presented.published_or_final_versio

Management of primary immunodeficiency

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Juvenile chronic arthritis in Chinese children: a review of the local experience

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Outcomes of interferon alpha and ribavirin treatment for chronic hepatitis C in patients with normal serum aminotransaminases

INTRODUCTION: Information on treatment outcomes with interferon plus ribavirin combination therapy in chronic hepatitis C patients with normal alanine aminotransaminase (ALT) levels is limited. AIM: The aims of this study were to assess outcomes of treatment with interferon plus ribavirin in patients with normal ALT levels (normal ALT group, n=52) compared with those with elevated ALT levels (raised ALT group, n=53), and to document the rate at which patients with normal ALT levels have an apparent worsening of disease, as shown by increases in ALT levels. RESULTS: At the end of treatment (week 48), 31 patients (59.6%) in the normal ALT group and 30 patients (56.6%) in the raised ALT group had undetectable hepatitis C virus (HCV) RNA (p=0.75). A sustained virological response (SVR) was achieved in 20 patients (38.5%) in the normal ALT group and in 21 patients (39.6%) in the raised ALT group (p=0.90). Patients were subsequently followed up for a median of 29.8 (interquartile range 25th-75th percentile (IQR) 20.8-36.2) months in the normal ALT group and for a median of 26.1 (IQR 17.7-36.3) months in the raised group (p=0.20) after week 72 of treatment. Among patients without SVR in the normal ALT group, only three patients (9.4%) developed persistently raised ALT levels following therapy. CONCLUSIONS: Combination therapy with interferon plus ribavirin is associated with a similar SVR in patients with normal ALT levels compared with those with elevated ALT levels. In patients with normal ALT levels, virological non-response to therapy results in new elevations in serum ALT levels in a small minority only.published_or_final_versio

Identification of five novel WASP mutations in Chinese families with Wiskott-Aldrich syndrome.

The Wiskott-Aldrich Syndrome (WAS) is an X-linked recessive immunodeficiency caused by mutation in the gene encoding WAS protein (WASP). The disease is characterized by eczema, thrombocytopenia and severe immunodeificency and is associated with extensive clinical heterogeneity. Mutation studies indicated that the mutated genotypes are also highly variable. In this study, we performed PCR-direct sequencing analysis of the WAS gene in six unrelated Chinese families. Five novel mutations identified, included two nonsense mutations (506C-->T, 1388-->T), a small insertion (685-686insCGCA) and two single-base deletions (384delT, 984delC). All of the mutations are predicted to lead to premature translational termination of WASP. Copyright 2002 Wiley-Liss, Inc.postprin

Implication of the overlap representation for modelling generalized parton distributions

Based on a field theoretically inspired model of light-cone wave functions, we derive valence-like generalized parton distributions and their double distributions from the wave function overlap in the parton number conserved s-channel. The parton number changing contributions in the t-channel are restored from duality. In our construction constraints of positivity and polynomiality are simultaneously satisfied and it also implies a model dependent relation between generalized parton distributions and transverse momentum dependent parton distribution functions. The model predicts that the t-behavior of resulting hadronic amplitudes depends on the Bjorken variable x_Bj. We also propose an improved ansatz for double distributions that embeds this property.Comment: 15 pages, 8 eps figure

Human oropharynx as natural reservoir of Streptobacillus hongkongensis

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Primary immunodeficiency in Hong Kong and the use of genetic analysis for diagnosis

Objectives. To review the management of primary immunodeficiency and discuss recent advances in genetic analysis. Design. Retrospective study. Setting. University teaching hospital, Hong Kong. Patients. Children diagnosed with primary immunodeficiency and followed up in the immunology clinic during the period 1988 to 2003. Main outcome measures. Demographic data, co-morbidities and treatment of patients, outcome and complications; identification of disease by genetic mutations. Results. Medical records of a total of 117 patients (72 male, 45 female) diagnosed with primary immunodeficiency in the Department of Paediatrics and Adolescent Medicine, Queen Mary Hospital, Hong Kong during the past 15 years (1988-2003) were reviewed. All patients were followed up in the immunology clinic. Some patients had been referred from the private sector or other hospitals for immunological workup. Six categories of primary immunodeficiency were identified: predominantly humoral defect (n=50), predominantly cellular defect (n=22), combined humoral and cellular defect (n=5), phagocytic defect (n=18), complement disorders (n=4), and others (n=18). Although infection was the underlying cause of most co-morbidities and mortality, autoimmune (n=7) and allergic (n=23) manifestations were common. In addition, three patients developed lymphoma. Recent advances in the genetic diagnosis of several types of primary immunodeficiency were also reviewed: X-linked Wiskott-Aldrich syndrome, X-linked chronic granulomatous disease, X-linked agammaglobulinaemia, X-linked lymphoproliferative syndrome, leukocyte adhesion disease type I, and X-linked hyperimmunoglobulin M syndrome. This provides an invaluable means of understanding the molecular basis of primary immunodeficiency and has important clinical applications. Conclusions. Co-morbidities like autoimmune disease and allergic disease are common in patients with primary immunodeficiency and should be carefully evaluated. Likewise, a diagnosis of primary immunodeficiency should be considered when evaluating patients with these conditions. Rapid progress in the field of molecular genetics will enable definite and early diagnosis, and more importantly, potential curative therapy to be administered.published_or_final_versio

Force measurement by visibility modulated fiber optic sensor

Author name used in this publication: K. H. WongVersion of RecordPublishe