Density based fuzzy c-means clustering of non-convex patterns

We propose a new technique to perform unsupervised data classification (clustering) based on density induced metric and non-smooth optimization. Our goal is to automatically recognize multidimensional clusters of non-convex shape. We present a modification of the fuzzy c-means algorithm, which uses the data induced metric, defined with the help of Delaunay triangulation. We detail computation of the distances in such a metric using graph algorithms. To find optimal positions of cluster prototypes we employ the discrete gradient method of non-smooth optimization. The new clustering method is capable to identify non-convex overlapped d-dimensional clusters.

Robust ODF smoothing for accurate estimation of fiber orientation

Q-ball imaging was presented as a model free, linear and multimodal diffusion sensitive approach to reconstruct diffusion orientation distribution function (ODF) using diffusion weighted MRI data. The ODFs are widely used to estimate the fiber orientations. However, the smoothness constraint was proposed to achieve a balance between the angular resolution and noise stability for ODF constructs. Different regularization methods were proposed for this purpose. However, these methods are not robust and quite sensitive to the global regularization parameter. Although, numerical methods such as L-curve test are used to define a globally appropriate regularization parameter, it cannot serve as a universal value suitable for all regions of interest. This may result in over smoothing and potentially end up in neglecting an existing fiber population. In this paper, we propose to include an interpolation step prior to the spherical harmonic decomposition. This interpolation based approach is based on Delaunay triangulation provides a reliable, robust and accurate smoothing approach. This method is easy to implement and does not require other numerical methods to define the required parameters. Also, the fiber orientations estimated using this approach are more accurate compared to other common approaches.

Prediction of pedestrians routes within a built environment in normal conditions

Modelling and prediction of pedestrian routing behaviours within known built environments has recently attracted the attention of researchers across multiple disciplines, owing to the growing demand on urban resources and requirements for efficient use of public facilities. This study presents an investigation into pedestrians' routing behaviours within an indoor environment under normal, non-panic situations. A network-based method using constrained Delaunay triangulation is adopted, and a utility-based model employing dynamic programming is developed. The main contribution of this study is the formulation of an appropriate utility function that allows an effective application of dynamic programming to predict a series of consecutive waypoints within a built environment. The aim is to generate accurate sequence waypoints for the pedestrian walking path using only structural definitions of the environment as defined in a standard CAD format. The simulation results are benchmarked against those from the A* algorithm, and the outcome positively indicates the usefulness of the proposed method in predicting pedestrians' route selection activities. © 2014 Elsevier Ltd. All rights reserved.

Triangulation in organizational research : a re-presentation

This paper extends the discussion of postmodern thinking in organizational theory through a re-presentation of the concept of triangulation in organizational research. Initially triangulation is defined through the contrasting lenses of positivism and post-positivism/postmodernism and analysed as a metaphor for fixing and capturing the research subject. Subsequently triangulation is ‘re-presented’ as ‘metaphorization’—in terms of process and movement between researcher-subject positions. Rethinking the lines and angles of enquiry in triangulation, the paper suggests a shift from the ‘triangulation of distance’ tradition to a more reflexive consideration of ‘researcher stance’. This movement is represented across three perspectives: the researcher as a follower of nomothetic lines; the researcher as the taker of an ideographic overview; and the researcher as the finder of a particular angle. The implications of this re-presentation are then discussed in terms of perspective, data capture, reflexivity and metatriangulation.

The Εffects of censoring and the spiral of silence on focus group interviews: a case study of discussions on immigration

Focus groups assess the oral expressions of opinions of participants on a particular topic under discussion. They have several advantages over other qualitative research methodologies such as depth interviews because focus groups can discover people's attitudes and motivations while revealing the underlying views or values held by them. However, as focus groups elicit more socially expressed and contested opinions and discourses than Individual opinions, their discussions can be contaminated by the situational constraints and social pressures within the group. These include group dynamics, confonnity, censoring, the Group Leader Effect, the Groupthink Syndrome, the effects of the Spiral of Silence, characteristics of group members, and the climate of opinion within the group and in society at the time. This case study examines the effects of these factors on the 'horizontal interactions' between group members during a discussion with undecided voters about immigration, using two situations where focus group members took offence at comments made by another and challenged them, when the topic under discussion was personally relevant to them. Other members of the group, offending or otherwise, then remained silent, retracted their opinions to placate the challenger, and expressed neutral or conciliatory opinions in an effort to return the discussion to a state of equilibrium. It then examines some measures that can reduce such contaminations, including
methodological triangulation, where several methods and methodological
approaches are used to examine a given phenomenon, instead of just one method, such as the sole use of transcripts of focus group discussions.

Validation of a food-frequency questionnaire assessment of carotenoid and vitamin E intake using weighed food records and plasma biomarkers: the method of triads model.

Background: Reliability or validity studies are important for the evaluation of measurement error in dietary assessment methods. An approach to validation known as the method of triads uses triangulation techniques to calculate the validity coefficient of a food-frequency questionnaire (FFQ).

Objective: To assess the validity of an FFQ estimates of carotenoid and vitamin E intake against serum biomarker measurements and weighed food records (WFRs), by applying the method of triads. Design: The study population was a sub-sample of adult participants in a randomised controlled trial of b-carotene and sunscreen in the prevention of skin cancer. Dietary intake was assessed by a self-administered FFQ and a WFR. Nonfasting blood samples were collected and plasma analysed for five carotenoids (a-carotene, b-carotene, b-cryptoxanthin, lutein, lycopene) and vitamin E. Correlation coefficients were calculated between each of the dietary methods and the validity coefficient was calculated using
the method of triads. The 95% confidence intervals for the validity coefficients were estimated using bootstrap sampling.

Results: The validity coefficients of the FFQ were highest for a-carotene (0.85) and lycopene (0.62), followed by b-carotene (0.55) and total carotenoids (0.55), while the lowest validity coefficient was for lutein (0.19). The method of triads could not be used for b-cryptoxanthin and vitamin E, as one of the three underlying correlations was negative.

Conclusions: Results were similar to other studies of validity using biomarkers and the method of triads. For many dietary factors, the upper limit of the validity coefficients was less than 0.5 and therefore only strong relationships between dietary exposure and disease will be detected.

A discussion on passive location discovery in emitter networks using angle-only measurements

In this paper we discuss the ghost node problem found when triangulation of 2 or more nodes is required. We present and discuss a simple algorithm, termed ABLE (Angle Based Location Estimation), that will position randomly placed emitters in a wireless sensor network using a mobile antenna array. The individual nodes in the network are relieved of the localization task by the mobile antenna system and require no modifications to account for location determination. Furthermore, no beacon nodes (i.e. nodes that know their own position) are required. We provide analysis that indicates a reasonably small number of measurements are required to guarantee the successful
localization of the emitting nodes and demonstrate our results through simulation.

Nurse practitioner standards : an Australian and New Zealand research collaboration

This paper will report the findings from research conducted in Australia and New Zealand to inform development of standards for nurse practitioner education and practice competencies. In New Zealand and Australia the nurse practitioner is a new and unique level of health-care provider. The shifting boundaries caused by health-care reform have created impetus and demand for development of new models of health-care, but have also created some uncertainty regarding nurse practitioner standards, education and models of care. The title, Nurse Practitioner, is now legislated in New Zealand and most jurisdictions in Australia but there is scant research to inform development of nurse practitioner standards. This research, sponsored by the Australian Nursing Council and the Nursing Council of New Zealand, was conducted to develop generic standards that could be applied for the education, authorisation and practice of nurse practitioners in both countries. The study involved collection and triangulation of data from a range of sources across Australia and New Zealand including: in-depth interviews with 15 nurse practitioners from different geographical and clinical contexts; curriculum survey of all nurse practitioner courses in the two countries and interview with convenors of these courses; collation of the authorisation/registration processes and policies from states and territories in Australia, New Zealand and internationally. These data were analysed within and across the data modalities to provide information on standards for nurse practitioner practice and education. Findings from the study included identification of the core role of the nurse practitioner as it is expressed in New Zealand and Australia and generic standards for nurse practitioner competencies, education and authorisation. These findings will standardise expectations, support mutual recognition of nurse practitioner authorisation across the two countries and make an important contribution to the current international debate on nurse practitioner standards and scope of practice.

Disorganization theory; explorations in alternative organizational analysis

Contents: Paradigm plurality and its prospects -- Organizational knowledge : production and consumption -- Escaping the confines of organization theory / with Ian Atkin -- Actor-networks and sociological symmetry / with Christine McLean -- Fluidity and identity / with Beverly Metcalfe -- Time and temporality -- Decoration and disorganization / with Stella Minahan -- Governmentality and networks -- Actor-networks, research strategy and organization / with Nick Lee -- Rethinking triangulation -- Critical retrospective research -- Concluding remarks : a future agenda for alternative organization studies.