Physical Sciences and Mathematics Commons^™

Somatic Mutation And The Antarctic Ozone Hole, L. J. Clarke, Sharon A. Robinson, D. J. Ayre

Faculty of Science - Papers (Archive)

1 Previous studies of Antarctic clonal moss populations using RAPD markers have reported extraordinarily high levels of genetic variation. This has been claimed to reflect somatic mutation, possibly resulting from elevated UV-B radiation. 2 Our study used microsatellite markers to compare the genetic variation present within continental Antarctic, sub-Antarctic and temperate populations of the moss Ceratodon purpureus. 3 In contrast to the RAPD studies, microsatellite data revealed that C. purpureus populations from continental Antarctica display less intra-population genetic diversity than populations from a range of temperate and sub-Antarctic sites. 4 Analysis of Molecular Variation (AMOVA) revealed that populations within the …

Solvent Isotope Effect On Macromolecular Dynamics In E. Coli, M. Jasnin, M. Tehei, M. Moulin, M. Haertlein, G. Zaccai

Faculty of Science - Papers (Archive)

Elastic incoherent neutron scattering was used to explore solvent isotope effects on average macromolecular dynamics in vivo. Measurements were performed on living E. coli bacteria containing H2O and D2O, respectively, close to physiological conditions of temperature. Global macromolecular flexibility, expressed as mean square fluctuation (MSF) values, and structural resilience in a free energy potential, expressed as a mean effective force constant, hk0i, were extracted in the two solvent conditions. They referred to the average contribution of all macromolecules inside the cell, mostly dominated by the internal motions of the protein fraction. Flexibility and resilience were both found to be smaller …

Synchronicity Of Thermogenic Activity, Alternative Pathway Respiratory Flux, Aox Protein Content, And Carbohydrates In Receptacle Tissues Of Sacred Lotus During Floral Development, Nicole M. Grant, Rebecca E. Miller, Jennifer R. Watling, Sharon A. Robinson

Faculty of Science - Papers (Archive)

The relationships between heat production, alternative oxidase (AOX) pathway flux, AOX protein, and carbohydrates during floral development in Nelumbo nucifera (Gaertn.) were investigated. Three distinct physiological phases were identified: pre-thermogenic, thermogenic, and post-thermogenic. The shift to thermogenic activity was associated with a rapid, 10-fold increase in AOX protein. Similarly, a rapid decrease in AOX protein occurred post-thermogenesis. This synchronicity between AOX protein and thermogenic activity contrasts with other thermogenic plants where AOX protein increases some days prior to heating. AOX protein in thermogenic receptacles was significantly higher than in post-thermogenic and leaf tissues. Stable oxygen isotope measurements confirmed that the …

The Inhabitation Problem For Intersection Types, M. W. Bunder

Faculty of Informatics - Papers (Archive)

In the system lambda ^ of intersection types, without w, the problem as to whether an arbitrary type has an inhabitant, has been shown to be undecidable by Urzyczyn in [9]. For one subsystem of lambda ^, that lacks the ^- introduction rule, the inhabitation problem has been shown to be decidable in Kurata and Takahashi [9]. The natural question that arises is: What other subsystems of lambda ^, have a decidable inhabitation problem? The work in [2], which classifies distinct and inhabitation-distinct subsystems of lambda ^, leads to the extension of the undecidability result to lambda ^ without the …

Modeling Dynamic Controls On Ice Streams: A Bayesian Statistical Approach, L Mark Berliner, Kenneth Jezek, Noel Cressie, Yongku Kim, Calvin Lam, Cornelis Van Der Veen

Faculty of Informatics - Papers (Archive)

Our main goal is to exemplify the study of ice-stream dynamics via Bayesian statistical analysis incorporating physical, though imperfectly known, models using data that are both incomplete and noisy. The physical-statistical models we propose account for these uncertainties in a coherent, hierarchical manner. The initial modeling assumption estimates basal shear stress as equal to driving stress, but subsequently includes a random corrector process to account for model error. The resulting stochastic equation is incorporated into a simple model for surface velocities. Use of Bayes' theorem allows us to make inferences on all unknowns given basal elevation, surface elevation and surface …

Vulnerability Assessment Of Power System Using Radial Basis Function Neural Network And A New Feature Extraction Method, Ahmed M. Haidar, Azah Mohamed, Aini Hussain

Faculty of Informatics - Papers (Archive)

Vulnerability assessment in power systems is important so as to determine how vulnerable a power system in case of any unforeseen catastrophic events. This paper presents the application of Radial Basis Function Neural Network (RBFNN) for vulnerability assessment of power system incorporating a new proposed feature extraction method named as the Neural Network Weight Extraction (NNWE) for dimensionality reduction of input data. The performance of the RBFNN is compared with the Multi Layer Perceptron Neural Network (MLPNN) so as to evaluate the effectiveness of the RBFNN in assessing the vulnerability of a power system based on the indices, power system …

Some Diagnostics For Markov Random Fields, Noel A. Cressie, Prasenjit Kapat

Faculty of Informatics - Papers (Archive)

The development of diagnostics to check the fit of a proposed Markov random field (MRP) to data is a very important problem in spatial statistics. In this article, the consequences of fitting a given MRF to spatial data are visualized using diagnostic plots. The Gaussian MRF known as the conditional autoregressive model is featured. Various types of departures of the data from the fitted MRF model are calculated, allowing locally influential observations to be highlighted using the MRF-Neighborhoods plot. Through a global summary statistic and the Model-Comparison plot, we compare MRF models that differ both in terms of the neighborhood …

It Offshoring Risks And Governance Capabilities, Akemi T. Chatfield, Padmaharsha Wanninayaka

Faculty of Informatics - Papers (Archive)

IT offshoring or offshore outsourcing is a fast growing trend that is worldwide and continuing. Driven by the competitive pressure to reduce IT costs, firms in developed countries opt to buy IT services from offshore service providers in developing countries, which provide comparative advantage in lower labour costs and skilled workforce. While much has been written about its relative costs and benefits, there is a lack of comprehensive research on risks of IT offshoring. This research aims to identify IT offshoring risks based on a comprehensive review of the literature and content analysis. It also aims to map those risks …

Generalised Linear Mixed Model Analysis Via Sequential Monte Carlo Sampling, Y Fan, D S. Leslie, M P. Wand

Faculty of Informatics - Papers (Archive)

We present a sequential Monte Carlo sampler algorithm for the Bayesian analysis of generalised linear mixed models (GLMMs). These models support a variety of interesting regression-type analyses, but performing inference is often extremely difficult, even when using the Bayesian approach combined with Markov chain Monte Carlo (MCMC). The Sequential Monte Carlo sampler (SMC) is a new and general method for producing samples from posterior distributions. In this article we demonstrate use of the SMC method for performing inference for GLMMs. We demonstrate the effectiveness of the method on both simulated and real data, and find that sequential Monte Carlo is …

Finding Symmetries By Incorporating Initial Conditions As Side Conditions, J. M. Goard

Faculty of Informatics - Papers (Archive)

It is generally believed that in order to solve initial value problems using Lie symmetry methods, the initial condition needs to be left invariant by the infinitesimal symmetry generator that admits the invariant solution. This is not so. In this paper we incorporate the imposed initial value as a side condition to find ‘infinitesimals’ from which solutions satisfying the initial value can be recovered, along with the corresponding symmetry generator.

Lie Symmetry Methods In Finance: An Example Of The Bond Pricing Equation, Joanna M. Goard

Faculty of Informatics - Papers (Archive)

Using Lie’s classical method of group invariants, new solutions are found for the valuation of zero-coupon bonds. In finding the solutions, the model for the underlying short-term interest rate assumes a realistic time-dependent, mean-reverting drift form and a power-law volatility.

An Operational Model For A Well-Stirred Membrane Bioreactor: Reactor Performance Analysis, Mark Nelson, Harvinder Sidhu, Soji Adesina

Faculty of Informatics - Papers (Archive)

We investigate the behavior of a reaction described by Michaelis-Menten kinetics in an immobilised enzyme reactor (IER). The IER is treated as a well-stirred flow reactor, in which the bound and unbounded enzyme species are immobilized and therefore constrained to remain within the reaction vessel. The product species leaves the bioreactor either in the reactor outflow or by permeating through the semi-permeable reactor wall. We explore how the concentration of recovered product and the reactor productivity vary with process parameters, particularly those associated with the separation of the product from the substrate through the semi-permeable reactor wall. We show that …

Formal Concept Analysis For E-Learning, Ghassan Beydoun

Faculty of Informatics - Papers (Archive)

We capture student interactions in an e-learning community to construct a semantic web (SW) to create a collective meta-knowledge structure guiding students as they search the existing knowledge corpus. We use formal concept analysis (FCA) as a knowledge acquisition tool to process the students virtual surfing trails to express and exploit the dependencies between web-pages to yield subsequent and more effective focused search results. We mirror social navigation and bypass the cumbersome manual annotation of webpages and at the same time paralleling social navigation for knowledge. We present our system KAPUST2 (Keeper and Processor of User Surfing Trails) which constructs …

Chord4s: A P2p-Based Decentralised Service Discovery Approach, Qiang He, Jun Yan, Yun Yang, Ryszard Kowalczyk, Hai Jin

Faculty of Informatics - Papers (Archive)

Service-oriented computing is emerging as a paradigm for developing distributed applications. A critical issue of utilising service-oriented computing is to have a scalable, reliable and robust service discovery mechanism. However, traditional service discovery methods using centralised registries can easily suffer from problems such as performance bottleneck and vulnerability to failures in the large scalable service network, thus functioning abnormally. To address these problems, this paper proposes a peer-to-peer based decentralised service discovery approach named Chord4S. Chord4S utilises the data distribution and lookup capabilities of the popular Chord to distribute and discover services in a decentralised manner. Data availability is further …

Towards An Enterprise Business Process Architecture Standard, George Koliadis, Aditya K. Ghose, Srinivas Padmanabhuni

Faculty of Informatics - Papers (Archive)

An effective process architecture helps provide a high-level blueprint of the complexity underlying an enterprise, which is used by executive committees during key decision and change processes. As existing service standards focus on co-ordination, they fall short in describing the motivational structure depicted in such models. In order to progress towards standardization in this area of complexity, we discuss the practicality of a process architecture, and present a set of 22 questions that can be used in the functional evaluation and construction of a process architecture. We use these questions to evaluate the current “state-of-the-art” in business process architecture. We …

Modelling Quality And Spatial Characteristics For Autonomous E-Service Peers, Jun Shen, Shuai Yuan

Faculty of Informatics - Papers (Archive)

In this paper, we present an autonomous and scalable WSMO-based methodology to describe quality of service (QoS) and geographic features of e-services in a peer-to-peer based environment. To fully explore the usability of service mining and categorisation, we designed an algorithm to select the most appropriate peers to improve effective service composition.

A Practical Geographic Ontology For Spatial Web Services, Shuai Yuan, Jun Shen, Jun Yan

Faculty of Informatics - Papers (Archive)

The application of ontology in Web services context for dynamic discovery, autonomous composition, invocation and monitoring has been deemed as very promising in semantic Web based enterprise application integration and m-commerce. There are many initiatives aiming to realize pervasive services to enable effective enactment of better quality of services, such as sensitiveness on service locations. The traditional WSDL is hardly qualified enough to tackle new challenges such as accurate representation of the non-functional properties of services. Hence, OWL-S came up with an effectual approach to facilitating semantic service description, dynamic composition, on-the-fly execution, and many other tasks. In this paper, …

Mining E-Services In P2p-Based Workflow Enactments, Shuai Yuan, Jun Shen

Faculty of Informatics - Papers (Archive)

This paper aims to explore the feasible mining and proper selection of QoS-aware services for a P2P-based business process enactment framework, and enhance the relevant workflow prototype.

Through observing and analysing unpredictable dynamic changes which commonly exist in e-service workflow, we propose a set of QoS specifications and monitoring mechanisms in a P2P workflow framework. These specifications are an evolving extension of services’ description with semantic Web facilitators for P2P-based e-services.

It has been demonstrated that our QoS-OWL approach can be effectively used to describe and exploit e-services, particularly in decentralised environment. QoS-OWL is also able to provide the deliberation …

A Flexible And Reasonable Mechanism For Self-Interested Agent Team Forming, Q. Bai, Minjie Zhang

Faculty of Informatics - Papers (Archive)

As social entities, intelligent agents need to collaborate with others regardless of whether they are cooperative or self interested. Compared with cooperative agents, collaborations among self-interested agents are more complex and dynamic due to the selfish features. Self-interested agents are impelled to cooperate with others by their individual goals. In an agent team composed of self-interested agents, "common" goals of agents may change to be conflicted as the environment changes.

Non-Optimal Receiver For Space Time Spreading Across A Time Hopping Over Ultra Wideband Ppm, Peter James Vial, Beata J. Wysocki, Tadeusz A. Wysocki

Faculty of Informatics - Papers (Archive)

A novel non-optimal chip based technique is proposed to use two antennas to transmit data across a Direct Sequence Time Hopping Ultra Wideband dual antenna wireless communication system to a single receiver. The spread data is sent over the independent channels using the Space Time Spreading technique to encode the chips which are sent on each antenna simultaneously. A hard decision is made at each chip of the spreading code received based on the known Channel State Information which Pulse Position Modulated signal was received from each antenna. The paper shows that by adapting the Space Time Spreading technique to …

New Orthogonal Designs From Weighing Matrices, Ilias Kotsireas, Christos Koukouvinos, Jennifer Seberry

Faculty of Informatics - Papers (Archive)

In this paper we show the existence of new orthogonal designs, based on a number of new weighing matrices of order 2n and weights 2n − 5 and 2n−9 constructed from two circulants. These new weighing matrices were constructed recently by establishing various patterns on the locations of the zeros in a potential solution, in conjunction with the power spectral density criterion. We also demonstrate that some of these new orthogonal designs, the ones that are full, can be used to construct inequivalent Hadamard matrices.

A New Link Scheduling Algorithm For Concurrent Tx/Rx Wireless Mesh Networks, Kwan-Wu Chin

Faculty of Informatics - Papers (Archive)

Wireless routers equipped with smart antennas are capable of forming beams to neighboring devices to transmit/receive multiple packets simultaneously, hence achieving high network capacity. This however is dependent on the link scheduling algorithm employed by these routers. To this end, we describe a simple link activation algorithm that tradeoffs path length to increase network capacity. We show via analysis and simulation that the proposed algorithm improves network capacity and lowers end-to-end delay despite a slight increase in path length.

A Spatially Aware Rfid-Enhanced Wireless Sensor Network, Dheeraj Klair, Kwan-Wu Chin, Raad Raad, Darryn Lowe

Faculty of Informatics - Papers (Archive)

Radio frequency identification (RFID) systems are becoming increasingly popular for automatic object identification and supply chain management. Wide acceptance of this technology has led to several new areas of research, one of which is RFID-enhanced wireless sensor networks (WSNs). Such networks have the ability to self-organize, identify tagged objects, perform localization, and carry out searches; all of which are enablers of pervasive computing. This paper therefore presents various challenges to creating such networks, and describes our recent research on energy efficient RFID tag reading protocols.

Calibrating Mean-Reverting Jump Diffusion Models: An Application To The Nsw Electricity Market, Jamie Alcock, J. M. Goard, Tony Vassallo

Faculty of Informatics - Papers (Archive)

[extract] In recent years the Australian National Electricity Market (the NEM) has been undergoing the transition to a fully deregulated marketplace. In December 1998, for the first time, the wholesale price of electricity was subject to market forces. The NEM includes the Queensland, New South Wales, Victorian, South australian, Tasmanian and Australian Capital Territory electricity markets. Almost 8 million end users are supplied by the world's longest interconnected power system, and the NEM trades up to $7 billion of electricity annually.

Power-Law And Stable Distributions Of Bgp Paths, Julien Clement, Kwan-Wu Chin

Faculty of Informatics - Papers (Archive)

This paper presents two new properties of BGP routes. First, it shows that the frequency of autonomous systems (ASs) appearing in path vectors follow a Power-Law relationship. Secondly, it shows that path lengths can be characterized accurately by stable distributions. The main implication of these properties is that it allows the creation of realistic forwarding tables for simulation studies. Moreover, they extend previous works that have thus far only shown Power-Law relationships exhibited by ASs degree.

On The Viability And Performance Of Dns Tunneling, Tom Van Leijenhorst, Kwan-Wu Chin, Darryn Lowe

Faculty of Informatics - Papers (Archive)

DNS tunnels are network covert channels that allow the transmission of arbitrary data using the DNS infrastructure. Users can use such tunnels to hide their communication sessions in order to bypass local security and accounting policies. Hence, it is important that we investigate the viability and performance of DNS tunneling. Our results show that clients can obtain up to 110 KB/s in throughput, and delays as low as 150ms. These results, however, incur very high overheads. In the worst case, clients generate up to 2000% more traffic!

Are There Hilbert-Style Pure Type Systems?, Martin Bunder, Willibrordus Dekkers

Faculty of Informatics - Papers (Archive)

For many a natural deduction style logic there is a Hilbert-style logic that is equivalent to it in that it has the same theorems (i.e. valid judgements with empty contexts). For intuitionistic logic, the axioms of the equivalent Hilbert-style logic can be propositions which are also known as the types of the combinators I, K and S. Hilbert-style versions of illative combinatory logic have formulations with axioms that are actual type statements for I, K and S. As pure type systems (PTSs)are, in a sense, equivalent to systems of illative combinatory logic, it might be thought that Hilbert-style PTSs (HPTSs) …

Modelling Social Networks As Authorised Domains With Decay, Nicholas Sheppard, Reihaneh Safavi-Naini

Faculty of Informatics - Papers (Archive)

Sharing multimedia among friends and acquaintances is a common practice that, in appropriate settings, need not be detrimental to the interests of copyright owners. In this paper, we propose a model for sharing multimedia based on the notion of an acquaintance domain whose members will have access to the domain owner’s multimedia. Membership of an acquaintance domain is determined by the closeness of a relationship – where “closeness” can be defined by factors such as the frequency of visits – and membership of the domain deteriorates as the relationship becomes more distant. We have made an implementation of the proposal …

A Hierarchical Learning Network For Face Detection With In-Plane Rotation, Fok Hing Chi Tivive, Abdesselam Bouzerdoum

Faculty of Informatics - Papers (Archive)

This paper presents a scale and rotation invariant face detection system. The system employs a hierarchical neural network, called SICoNNet, whose processing elements are governed by the nonlinear mechanism of shunting inhibition. The neural network is used as a face/nonface classifier that can handle in-plane rotated patterns. To train the network as a rotation invariant face classifier, an enhanced bootstrap training technique is developed, which prevents bias towards the nonface class. Furthermore, a multi-resolution processing is employed for scale invariance: an image pyramid is formed through subsampling and face detection is performed at each scale of the pyramid using an …

Multivariate Autoregressive Modelling Of Multichannel Reverberant Speech, Eva Cheng, Ian Burnett, Christian Ritz

Faculty of Informatics - Papers (Archive)

Recent research in speech localization and dereverberation introduced processing of the multichannel linear prediction (LP) residual of speech recorded with multiple microphones. This paper investigates the novel use of intra- and inter-channel speech prediction by proposing the use of a multichannel LP model derived from multivariate autoregression (MVAR), where current LP approaches are based on univariate autoregression (AR). Experiments were conducted on simulated anechoic and reverberant synthetic speech vowels and real speech sentences; results show that, especially at low reverberation times, the MVAR model exhibits greater prediction gains from the residual signal, compared to residuals obtained from univariate AR models …