Energetics of interlimb coordination

While the traditional dependent variables of motor skill learning are accuracy and consistency of movement outcome, there has been increasing interest in aspects of motor performance that are described as reflecting the ‘energetics’ of motor behaviour. One defining characteristic of skilled motor performance is the ability to complete the task with minimum energy expenditure (Sparrow & Newell, 1998). A further consideration is that movements also have costs in terms of cognitive ‘effort’ or ‘energy’. The present project extends previous work on energy expenditure and motor skill learning within a coordination dynamics framework. From the dynamic pattern perspective, a coordination pattern lowest on the 11KB model potential curve (Haken, Kelso & Bunz, 1985) is more stable and least energy is required to maintain pattern stability (Temprado, Zanone, Monno & Laurent, 1999). Two experiments investigated the learning of stable and unstable coordination patterns with high metabolic energy demand. An experimental task was devised by positioning two cycle ergometers side-by-side, placing one foot on each, with the pedals free to move independently at any metronome-paced relative phase, Experiment 1 investigated practice-related changes to oxygen consumption, heart rate, relative phase, reaction time and muscle activation (EMG) as participants practiced anti-phase, in-phase and 90°-phase cycling. Across six practice trials metabolic energy cost reduced and AE and VE of relative phase declined. The trend in the metabolic and reaction time data and percent co-contraction of muscles was for the in-phase cycling to demonstrate the highest values, anti-phase the lowest and 90°-phase cycling in-between. It was found that anti- and in-phase cycling were both kinematically stable but anti-phase coordination revealed significantly lower metabolic energy cost. It was, therefore, postulated that of two equally stable coordination patterns, that associated with lower metabolic energy expenditure would constitute a stronger attractor. Experiment 2 was designed to determine whether a lower or higher energy-demanding coordination pattern was a stronger attractor by scanning the attractor layout at thirty-degree intervals from 0° to 330°. The initial attractor layout revealed that in-phase was most stable and accurate, but the remaining coordination patterns were attracted to the low energy cost anti-phase cycling. In Experiment 2 only 90°- phase cycling was practiced with a post-test attractor layout scan revealing that 90°-phase and its symmetrical partner 270°-phase had become attractors of other coordination patterns. Consistent with Experiment 1, practicing 90°-phase cycling revealed a decline in AE and VE and a reduction in metabolic and cognitive cost. Practicing 90°-phase cycling did not, however, destabilise the in-phase or anti-phase coordination patterns either kinematically or energetically. In summary, the findings suggest that metabolic and mental energy can be considered different representations of a ‘global’ energy expenditure or ‘energetic’ phenomenon underlying human coordination. The hypothesis that preferred coordination patterns emerge as stable, low-energy solutions to the problem of inter-and intra-limb coordination is supported here in showing that the low-energy minimum of coordination dynamics is also an energetic minimum.

Chaos theory based detection against network mimicking DDoS attacks

DDoS attack traffic is difficult to differentiate from legitimate network traffic during transit from the attacker, or zombies, to the victim. In this paper, we use the theory of network self-similarity to differentiate DDoS flooding attack traffic from legitimate self-similar traffic in the network. We observed that DDoS traffic causes a strange attractor to develop in the pattern of network traffic. From this observation, we developed a neural network detector trained by our DDoS prediction algorithm. Our preliminary experiments and analysis indicate that our proposed chaotic model can accurately and effectively detect DDoS attack traffic. Our approach has the potential to not only detect attack traffic during transit, but to also filter it.

CADET - Centre for Advanced Design in Engineering Training

BACKGROUND : The Centre for Advanced Design in Engineering Training (CADET) is a partnership of Deakin University and the Gordon Institute of TAFE that will improve access and pathways into careers to address Australia’s critical engineering skills shortage (Walton, C). Local high schools, Belmont High and Matthew Flinders Girls Secondary College are included as strategic partners. CADET is proposed to be a teaching and learning facility providing a project focused modern engineering approach to students at regional schools and TAFE as well as Deakin’s degree programs. CADET will emphasize engineering design and development through virtual and physical modelling, simulation and prototyping – skills at the heart of the 21st century engineering challenges, and will serve as an attractor to engineering and related professions.

PURPOSE : The purpose of this paper is to present an argument toward the development of a Centre for advanced design in engineering training. CADET is proposed to increase the awareness and attractiveness of engineering as an education and career option, particularly for women, in regional schools, provide under one roof state-of-the-art engineering design, modelling and prototyping facilities, facilitate access and articulation pathways between school, VET and Higher Education, increase the physical capacity to serve student demand in western Victoria, and reinvigorate engineering as an essential component of a skilled regional economy.

DESIGN/METHOD : The evidenced based argument towards the proposed centre for advanced design in engineering training is based on a detailed literature review as well as a research study with industry representatives in engineering design. The learning principles of the model are also investigated and aligned to the proposed centre.

RESULTS : CADET is a change to the way engineering has traditionally been taught. The outcomes of CADET will be to provide a broad range of contemporary/relevant teaching programs, improve the social benefits gained from teaching programs, improve retention rates, advance partnerships that link with rural and regional victoria, and collaborate with local communities to encourage governments to support regional capacity building. Through focus group interviews and open discussions with industry and academia over the past 12 months on the integration of design skills in engineering education, results indicate that the following key skills are essential elements required for a successful project oriented design based learning curriculum are creative & innovative skills, successful industry engagement, and awareness of design skills in early years. Feedback also showed that 80% of the industry representatives are looking to recruit graduates who acquired design-equipped skill and 60% indicated that they want graduates who acquired knowledge through projects.

CONCLUSIONS : CADET projected benefits are significant at the strategic and operational levels. They include access for more women in engineering, facilitates articulation pathways between VET and HE, targeted recognised critical current engineering skills shortage in Australia, improvement of regional access, attractiveness and participation in tertiary education, achievement of a significant improvement in the teaching-research nexus.

Material writing: Towards hybrid-making

Writing operates in an expanding field of intersections between symbol, inflection and further meaning. The materiality of writing, its embodied action, situated context and myriad substantive expressions, requires an interdisciplinary approach best advanced by collaborative teams and fuelled by collective concerns. At a recent design conference, Doha 2013: Hybrid Making, our team of creative arts researchers (Jondi Keane, Patrick West and Valerie Jeremijenko) conducted a workshop based on the idea of reverse engineering the notion of a souvenir, by starting with the sensation rather than the iconic image. The approaches explored by the group focused on the ways in which a sensation, emotion and/or idea attach to an object and how an object offers itself as an attractor for memory and indicate that when experience, sensation and place are emphasized, the materiality of writing comes to the fore. We assert that material writing allows or even requires a fluid movement between conceptual and perceptual modes of creative practice. In this paper we will unpack different methods of material writing: the materiality of the act of writing with substances, site-specific/site-conditioned writing and 3D printing. Through the particularity of each mode of material writing our discussions will examine the points of attachment that we, as symbolizing creatures, produce in order to orient and reconstruct a world on the fly. Material writing constantly brings us back to earth, anchoring us to the expanded processes integral to hybrid-making.

DEGENERATE HOPF BIFURCATIONS IN CHUA'S SYSTEM

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

DYNAMICS AT INFINITY of A CUBIC CHUA'S SYSTEM

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

HOPF BIFURCATION FROM LINES of EQUILIBRIA WITHOUT PARAMETERS IN MEMRISTOR OSCILLATORS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Bifurcation analysis of a new Lorenz-like chaotic system

In this paper we study the local codimension one and two bifurcations which occur in a family of three-dimensional vector fields depending on three parameters. An equivalent family, depending on five parameters, was recently proposed as a new chaotic system with a Lorenz-like butterfly shaped attractor and was studied mainly from a numerical point of view, for particular values of the parameters, for which computational evidences of the chaotic attractor was shown. In order to contribute to the understand of this new system we present an analytical study and the bifurcation diagrams of an equivalent three parameter system, showing the qualitative changes in the dynamics of its solutions, for different values of the parameters. (C) 2007 Elsevier Ltd. All rights reserved.

Global dynamics of the Rikitake system

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

On the global dynamics of the Rabinovich system

In this paper by using the Poincare compactification in R(3) make a global analysis of the Rabinovich system(x) over dot = hy - v(1)x + yz, (y) over dot = hx - v(2)y - xz, (z) over dot = -v(3)z + xy,with (x, y, z) is an element of R(3) and ( h, v(1), v(2), v(3)) is an element of R(4). We give the complete description of its dynamics on the sphere at infinity. For ten sets of the parameter values the system has either first integrals or invariants. For these ten sets we provide the global phase portrait of the Rabinovich system in the Poincare ball (i.e. in the compactification of R(3) with the sphere S(2) of the infinity). We prove that for convenient values of the parameters the system has two families of singularly degenerate heteroclinic cycles. Then changing slightly the parameters we numerically found a four wings butterfly shaped strange attractor.

Transition to turbulence in the Reynolds' experiment

In this study we simulate numerically the Reynolds' experiment for the transition from laminar to turbulent flow in a pipe. We present a discussion of the results from a dynamical systems perspective when a control parameter, the Reynolds number, is increased. The Landau scenario, where the transition is described by the excitation of infinite oscillatory modes within the fluid, is not observed. Instead what happens is best explained by the Ruelle-Takens scenario in terms of strange attractors. The Lyapunov exponent and fractal dimension for the attractor are calculated together with a measure of complex behaviour called the Lempel-Ziv complexity. (C) 2001 Elsevier B.V. B.V. All rights reserved.

Age constraints and fine tuning in variable-mass particle models

VAMP (variable-mass particle) scenarios, in which the mass of the cold dark matter particles is a function of the scalar field responsible for the present acceleration of the Universe, have been proposed as a solution to the cosmic coincidence problem, since in the attractor regime both dark energy and dark matter scale in the same way. We find that only a narrow region in parameter space leads to models with viable values for the Hubble constant and dark energy density today. In the allowed region, the dark energy density starts to dominate around the present epoch and consequently such models cannot solve the coincidence problem. We show that the age of the Universe in this scenario is considerably higher than the age for noncoupled dark energy models, and conclude that more precise independent measurements of the age of the Universe would be useful in distinguishing between coupled and noncoupled dark energy models.

Consequences of dark matter-dark energy interaction on cosmological parameters derived from type Ia supernova data

Models where the dark matter component of the Universe interacts with the dark energy field have been proposed as a solution to the cosmic coincidence problem, since in the attractor regime both dark energy and dark matter scale in the same way. In these models the mass of the cold dark matter particles is a function of the dark energy field responsible for the present acceleration of the Universe, and different scenarios can be parametrized by how the mass of the cold dark matter particles evolves with time. In this article we study the impact of a constant coupling delta between dark energy and dark matter on the determination of a redshift dependent dark energy equation of state w(DE)(z) and on the dark matter density today from SNIa data. We derive an analytical expression for the luminosity distance in this case. In particular, we show that the presence of such a coupling increases the tension between the cosmic microwave background data from the analysis of the shift parameter in models with constant w(DE) and SNIa data for realistic values of the present dark matter density fraction. Thus, an independent measurement of the present dark matter density can place constraints on models with interacting dark energy.

Non-supersymmetric attractors in BI black holes

We study attractor mechanism in extremal black holes of Einstein-Born-Infeld theories in four dimensions. We look for solutions which are regular near the horizon and show that they exist and enjoy the attractor behavior. The attractor point is determined by extremization of the effective potential at the horizon. This analysis includes the backreaction and supports the validity of non-supersymmetric attractors in the presence of higher derivative interactions in the gauge field part. (C) 2008 Elsevier B.V. All rights reserved.

Black hole partition function using the hybrid formalism of superstrings

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)