Periodic geodesics and geometry of compact Lorentzian manifolds with a Killing vector field

We study the geometry and the periodic geodesics of a compact Lorentzian manifold that has a Killing vector field which is timelike somewhere. Using a compactness argument for subgroups of the isometry group, we prove the existence of one timelike non self-intersecting periodic geodesic. If the Killing vector field is nowhere vanishing, then there are at least two distinct periodic geodesics; as a special case, compact stationary manifolds have at least two periodic timelike geodesics. We also discuss some properties of the topology of such manifolds. In particular, we show that a compact manifold M admits a Lorentzian metric with a nowhere vanishing Killing vector field which is timelike somewhere if and only if M admits a smooth circle action without fixed points.

ON INTEGRABLE CODIMENSION ONE ANOSOV ACTIONS OF R(k)

In this paper, we consider codimension one Anosov actions of R(k), k >= 1, on closed connected orientable manifolds of dimension n vertical bar k with n >= 3. We show that the fundamental group of the ambient manifold is solvable if and only if the weak foliation of codimension one is transversely affine. We also study the situation where one 1-parameter subgroup of R(k) admits a cross-section, and compare this to the case where the whole action is transverse to a fibration over a manifold of dimension n. As a byproduct, generalizing a Theorem by Ghys in the case k = 1, we show that, under some assumptions about the smoothness of the sub-bundle E(ss) circle plus E(uu), and in the case where the action preserves the volume, it is topologically equivalent to a suspension of a linear Anosov action of Z(k) on T(n).

Crossed products by twisted partial actions and graded algebras

For a twisted partial action e of a group G on an (associative non-necessarily unital) algebra A over a commutative unital ring k, the crossed product A x(Theta) G is proved to be associative. Given a G-graded k-algebra B = circle plus(g is an element of G) B-g with the mild restriction of homogeneous non-degeneracy, a criteria is established for B to be isomorphic to the crossed product B-1 x(Theta) G for some twisted partial action of G on B-1. The equality BgBg-1 B-g = B-g (for all g is an element of G) is one of the ingredients of the criteria, and if it holds and, moreover, B has enough local units, then it is shown that B is stably isomorphic to a crossed product by a twisted partial action of G. (c) 2008 Elsevier Inc. All rights reserved.

Story Circle : Digital Storytelling Around the World

Story Circle is the first collection ever devoted to a comprehensive international study of the digital storytelling movement. Exploring subjects of central importance on the emergent and ever-shifting digital landscape-consumer-generated content, memory grids, the digital storytelling youth movement, and micro-documentary- Story Circle pinpoints who is telling what stories, where, on what terms, and what they look and sound like.

Why, how, what for? : motivations, actions and expectations in habitual entrepreneurship

Principal topic: Is habitual entrepreneurship different? Answering this is important to the field, however there is little systematic evidence, thus far. We addresses this by examining the role experience plays at three possible points of difference: motivations, actions and expectations; and by comparing those currently in the process of starting a business with those who have recent success in business creation. Firstly, we assess the balance of opportunity versus necessity motivation, internally versus externally stimulated decision processes and future growth aspirations. Literature suggests novices are more likely motivated to nascency out of necessity, and favour a manageable business size, while habitual entrepreneurs are more likely motivated by internally stimulated or idea driven processes. Secondly, we examine actions undertaken by successful experienced founders during gestation, contrasting ‘information collection’ and ‘opportunity definition’. Drawing on prior research we expect novices more likely to have enacted ‘information search’ while habitual entrepreneurs enact ‘opportunity definition’. Thirdly, we examine perceptions of venture success, where findings on overconfidence suggest that habitual entrepreneurs expect a higher chance of success for their ventures, while inexperience leads novices to underestimate the difficulty of entrepreneurial survival. Method: Empirical evidence to test these conjectures was drawn from a screened random sample of over 1100 Australian nascent and newly started business ventures. This information was collected during 2007/8 using a telephone survey. Results and Implications: Why do habitual entrepreneurs keep coming back? Findings suggest that while the pursuit of opportunity is shared by novice and experienced entrepreneur alike, consideration of repeat entrepreneurship may be motivated by a desire for growth. While idea driven motivations might not delineate a distinction during nascency, it does seem to be a factor contributing to the success of young firms. This warrants further research. How do habitual entrepreneurs behave differently? It seems they act to clearly define market opportunities as a matter of priority during venture gestation. What effect does entrepreneurial experience have on future expectations? Clearly a sense of realism is drawn over the difficulties that might be faced, and accords more circumspect judgements of venture survival. This finding informs practitioners considering entrepreneurship for the first time.

Where the actions are : bring reality into virtual reality

This paper describes a work-in-progress on developing design environments that combine wireless and mobile technologies with augmented reality to facilitate bringing context from the physical environment to the virtual models for design work. One of the challenges for designers in a variety of end-user-oriented design disciplines such as architecture and industrial design has been capturing and replaying the contextual information of the intended domain of the artifact being designed. Either the technology is decidedly low-tech, such as charcoal drawings in a sketchbook, out-of-reach, such as immersive virtual reality CAVEs, or a “make-do” with existing technologies, such as a collage of digital photos. This paper describes a novel combination of “off-the-shelf” technologies that may allow designers more capability to create models using standard computer-aided design applications and augmented reality to combine the current, physical context with the projected, digital context. We demonstrate this approach in the building design domain to address a common problem in building construction, construction defect resolution.

Adaptive unsupervised learning of human actions

Automatic detection of suspicious activities in CCTV camera feeds is crucial to the success of video surveillance systems. Such a capability can help transform the dumb CCTV cameras into smart surveillance tools for fighting crime and terror. Learning and classification of basic human actions is a precursor to detecting suspicious activities. Most of the current approaches rely on a non-realistic assumption that a complete dataset of normal human actions is available. This paper presents a different approach to deal with the problem of understanding human actions in video when no prior information is available. This is achieved by working with an incomplete dataset of basic actions which are continuously updated. Initially, all video segments are represented by Bags-Of-Words (BOW) method using only Term Frequency-Inverse Document Frequency (TF-IDF) features. Then, a data-stream clustering algorithm is applied for updating the system's knowledge from the incoming video feeds. Finally, all the actions are classified into different sets. Experiments and comparisons are conducted on the well known Weizmann and KTH datasets to show the efficacy of the proposed approach.

Adaptive and phase transition behavior in performance of discrete multi-articular actions by degenerate neurobiological systems

The identification of attractors is one of the key tasks in studies of neurobiological coordination from a dynamical systems perspective, with a considerable body of literature resulting from this task. However, with regards to typical movement models investigated, the overwhelming majority of actions studied previously belong to the class of continuous, rhythmical movements. In contrast, very few studies have investigated coordination of discrete movements, particularly multi-articular discrete movements. In the present study, we investigated phase transition behavior in a basketball throwing task where participants were instructed to shoot at the basket from different distances. Adopting the ubiquitous scaling paradigm, throwing distance was manipulated as a candidate control parameter. Using a cluster analysis approach, clear phase transitions between different movement patterns were observed in performance of only two of eight participants. The remaining participants used a single movement pattern and varied it according to throwing distance, thereby exhibiting hysteresis effects. Results suggested that, in movement models involving many biomechanical degrees of freedom in degenerate systems, greater movement variation across individuals is available for exploitation. This observation stands in contrast to movement variation typically observed in studies using more constrained bi-manual movement models. This degenerate system behavior provides new insights and poses fresh challenges to the dynamical systems theoretical approach, requiring further research beyond conventional movement models.

Young children’s active citizenship : storytelling, stories, and social actions

This thesis inquires into possibilities for young children‘s active citizenship as provoked through a practice of social justice storytelling with one Preparatory1 class of children aged five to six years. The inquiry was practitioner-research, through a living educational theory approach cultivating an interrelational view of existing with others in evolving processes of creation. Ideas of young children‘s active citizenship were provoked and explored through storytelling, by a storytelling teacher-researcher, a Prep class of children and their teacher. The three major foci of the study were practice, narrative and action. A series of storytelling workshops with a Prep class was the practice that was investigated. Each workshop began with a story that made issues of social justice visible, followed by critical discussion of the story, and small group activities to further explore the story. The focus on narrative was based on the idea of story as a way knowing. Stories were used to explore social justice issues with young children. Metanarratives of children and citizenship were seen to influence possibilities for young children‘s active citizenship. Stories were purposefully shared to provoke and promote young children‘s active citizenship through social actions. It was these actions that were the third focus of the study. Through action research, a social justice storytelling practice and the children‘s responses to the stories were reflected on both in action and after. These reflections informed and shaped storytelling practice. Learning in a practice of social justice storytelling is explained through living theories of social justice storytelling as pedagogy. Data of the children‘s participation in the study were analysed to identify influences and possibilities for young children‘s active citizenship creating a living theory of possibilities for young children‘s active citizenship.

Development of a novel rolling-circle amplification technique to detect Banana streak virus which also discriminates between integrated and episomal virus sequences

Bananas are hosts to a large number of banana streak virus (BSV) species. However, diagnostic methods for BSV are inadequate because of the considerable genetic and serological diversity amongst BSV isolates and the presence of integrated BSV sequences in some banana cultivars which leads to false positives. In this study, a sequence non-specific, rolling-circle amplification (RCA) technique was developed and shown to overcome these limitations for the detection and subsequent characterisation of BSV isolates infecting banana. This technique was shown to discriminate between integrated and episomal BSV DNA, specifically detecting the latter in several banana cultivars known to contain episomal and/or integrated sequences of Banana streak Mysore virus (BSMyV), Banana streak OL virus (BSOLV) and Banana streak GF virus (BSGFV). Using RCA, the presence of BSMyV and BSOLV was confirmed in Australia, while BSOLV, BSGFV, Banana streak Uganda I virus (BSUgIV), Banana streak Uganda L virus (BSUgLV) and Banana streak Uganda M virus (BSUgMV) were detected in Uganda. This is the first confirmed report of episomally-derived BSUglV, BSUgLV and BSUgMV in Uganda. As well as its ability to detect BSV, RCA was shown to detect two other pararetroviruses, Sugarcane bacilliform virus in sugarcane and Cauliflower mosaic virus in turnip.

A participant’s response : recreating the circle with We Al-Li: a program for sharing and regeneration

Personal reflections on the We Al-Li Program

Full circle : the future of sustainable fashion manufacturing in New Zealand

Many fashion businesses in New Zealand have followed a global trend towards inexpensive off shore manufacturing. The transfer of the production of garments to overseas workers has had consequences for the wellbeing of local businesses, fashion designers and garment makers. The gradual decline of fashion manufacturing also appears to have resulted in a local fashion scene where many garments look the same in style, colour, fabric, cut and fit. The excitement of the past, where the majority of fashion designers established their own individuality through the cut and shape of the garments that they produced, may have been inadvertently lost in an effort to take advantage of cost savings achieved through mass production and manufacturing methods which are now largely unavailable in New Zealand. Consequently, a sustainable local fashion and manufacturing industry, with design integrity, seems further out of reach. This paper is focussed upon the thesis that the design and manufacture of a fashion garment, bearing in mind certain economic and practical restrictions at its inception, can contribute to a more sustainable fashion manufacturing industry in New Zealand.