Data assimilation method to de-noise and de-filter particle image velocimetry data

We present a variational data assimilation method in order to improve the accuracy of velocity fields v˜, that are measured using particle image velocimetry (PIV). The method minimises the space-time integral of the difference between the reconstruction u and v˜, under the constraint, that u satisfies conservation of mass and momentum. We apply the method to synthetic velocimetry data, in a two-dimensional turbulent flow, where realistic PIV noise is generated by computationally mimicking the PIV measurement process. The method performs optimally when the assimilation integration time is of the order of the flow correlation time. We interpret these results by comparing them to onedimensional diffusion and advection problems, for which we derive analytical expressions for the reconstruction erro

An exploratory study on the social and genotypic clustering of HIV infection in men having sex with men

OBJECTIVE: To explore the clustering of HIV infected men having sex with men (MSM) using social network approach in conjunction with the phylogenetic relationship of the virus strains. DESIGN: An exploratory study incorporating social network and phylogenetic analysis. METHODS: Recently diagnosed HIV-infected MSM attending one major HIV specialist clinic in Hong Kong were recruited in the study involving the administration of a self-administered questionnaire on behaviours and partnership patterns using a Likert Scale, the results of which were assessed using social network analysis and in context of the phylogenetic analysis from sequencing the HIV-1 pol gene, as part of the clinical investigation for genotypic resistance. Clusters were defined using social and molecular methods. RESULTS: An 'Internet-centred' cluster and 'Sauna-centred' cluster could be delineated using correspondence analysis and network diagrams. The main distinguishing features of MSM in the 'Internet-centred' social cluster were: younger age, higher education level, and multiple partner types. Three genetic clusters could be identified in the phylogenetic tree, two of which associated with Internet use and one with sauna for sex partnership. There were partial overlaps between social and genetic clusters. Characteristically, the virus strains in sauna users were more disperse compared with the closely knit configuration of those using Internet. CONCLUSION: The principle of the duality of place and person can be strategically applied in epidemiologic investigation. The characterization of MSM cluster using anonymized network data provides a potentially powerful tool for informing public health intervention. © 2009 Lippincott Williams & Wilkins, Inc.postprin

New "light" for one-world approach toward safe and effective control of animal diseases and insect vectors from leishmaniac perspectives

Light is known to excite photosensitizers (PS) to produce cytotoxic reactive oxygen species (ROS) in the presence of oxygen. This modality is attractive for designing control measures against animal diseases and pests. Many PS have a proven safety record. Also, the ROS cytotoxicity selects no resistant mutants, unlike other drugs and pesticides. Photodynamic therapy (PDT) refers to the use of PS as light activable tumoricides, microbicides and pesticides in medicine and agriculture.Here we describe "photodynamic vaccination" (PDV) that uses PDT-inactivation of parasites, i.e. Leishmania as whole-cell vaccines against leishmaniasis, and as a universal carrier to deliver transgenic add-on vaccines against other infectious and malignant diseases. The efficacy of Leishmania for vaccine delivery makes use of their inherent attributes to parasitize antigen (vaccine)-presenting cells. Inactivation of Leishmania by PDT provides safety for their use. This is accomplished in two different ways: (i) chemical engineering of PS to enhance their uptake, e.g. Si-phthalocyanines; and (ii) transgenic approach to render Leishmania inducible for porphyrinogenesis. Three different schemes of Leishmania-based PDV are presented diagrammatically to depict the cellular events resulting in cell-mediated immunity, as seen experimentally against leishmaniasis and Leishmania-delivered antigen in vitro and in vivo. Safety versus efficacy evaluations are under way for PDT-inactivated Leishmania, including those further processed to facilitate their storage and transport. Leishmania transfected to express cancer and viral vaccine candidates are being prepared accordingly for experimental trials.We have begun to examine PS-mediated photodynamic insecticides (PDI). Mosquito cells take up rose bengal/cyanosine, rendering them light-sensitive to undergo disintegration in vitro, thereby providing a cellular basis for the larvicidal activity seen by the same treatments. Ineffectiveness of phthalocyanines and porphyrins for PDI underscores its requirement for different PS. Differential uptake of PS by insect versus other cells to account for this difference is under study.The ongoing work is patterned after the one-world approach by enlisting the participation of experts in medicinal chemistry, cell/molecular biology, immunology, parasitology, entomology, cancer research, tropical medicine and veterinary medicine. The availability of multidisciplinary expertise is indispensable for implementation of the necessary studies to move the project toward product development

Beyond the therapeutic: a Habermasian view of self-help groups’ place in the public sphere

Self-help groups in the United Kingdom continue to grow in number and address virtually every conceivable health condition, but they remain the subject of very little theoretical analysis. The literature to date has predominantly focused on their therapeutic effects on individual members. And yet they are widely presumed to fulfil a broader civic role and to encourage democratic citizenship. The article uses Habermas’ model of the public sphere as an analytical tool with which to reconsider the literature on self-help groups in order to increase our knowledge of their civic functions. In doing this it also aims to illustrate the continuing relevance of Habermas’ work to our understanding of issues in health and social care. We consider, within the context of current health policies and practices, the extent to which self-help groups with a range of different forms and functions operate according to the principles of communicative rationality that Habermas deemed key to democratic legitimacy. We conclude that self-help groups’ civic role is more complex than is usually presumed and that various factors including groups’ leadership, organisational structure and links with public agencies can affect their efficacy within the public sphere

Problem-based learning in social work: A study of student learning outcomes

This study evaluated the effects of problem-based learning (PBL) in social work education. The participants were 132 second-year social work students who took the core courses of Social Work Theory and Practice and Skills Laboratory in the PBL mode. A 40-item scale was used to measure the students' perceptions of their social work knowledge, skills, and values, Biggs's Study Process Questionnaire and Revised Study Process Questionnaire were employed to examine their learning approaches. The results indicated positive learning outcomes, with the most significant gains occurring in knowledge and lesser gains being made in skills and values. The findings suggest that students with deep learning motives and approaches reap the most benefit from PBL. © 2007 Sage Publications.link_to_subscribed_fulltex

Beyond clinical trials and narratives: A participatory action research with cancer patient self-help groups

The self-help movement in Hong Kong has been gradually gaining its momentum in recent years. The primary purpose of the research was to give voice to the experiences and views of patients towards cancer care and to influence healthcare providers and policy makers to act on patients' agendas. Self-help groups and their members are mobilized through the research activities of focus groups, interviews and a patient forum to specify and act on their needs. This article describes the project and the participatory action research (PAR) strategies in the mobilization of, and collaboration with, patient groups in research design, data analysis, and dissemination of findings. The implications on healthcare practice, particularly within an era of reform and restructuring of the healthcare system, are discussed. © 2005 Elsevier Ireland Ltd. All rights reserved.link_to_subscribed_fulltex

Competing philosophies in the classroom: A challenge to Hong Kong teachers

The present paper examines the experiences of teachers in teaching children with special needs in mainstream schools and how they see and evaluate the feasibility of the new integration initiatives in Hong Kong. The data are based on individual and focus group interviews with general class teachers, resource class teachers and principals of mainstream schools admitting students with special needs. Teachers reported difficulties and problems in maintaining classroom discipline and ambivalence in meeting the competing demands between students with and without special needs. The structural constraints of implementing a rigidly defined curriculum and being accountable for good academic results regardless of student competence pose formidable obstacles in achieving the goals of integrated education. There is a conflict at the systemic level between the philosophy of academic excellence defined by grades on the one hand and the philosophy of equality and inclusion on the other. Improving parent participation, having an ample supply of funds, the provision of necessary equipment and facilities, the availability of pre- and in-service training to teachers, and additional manpower in counselling are the most urgently needed resources in facilitating teachers to engage in teaching students with special needs alongside others.link_to_subscribed_fulltex