Linear models for endocytic transformations from live cell imaging

Endocytosis is the process by which cells internalise molecules including nutrient proteins from the extracellular media. In one form, macropinocytosis, the membrane at the cell surface ruffles and folds over to give rise to an internalised vesicle. Negatively charged phospholipids within the membrane called phosphoinositides then undergo a series of transformations that are critical for the correct trafficking of the vesicle within the cell, and which are often pirated by pathogens such as Salmonella. Advanced fluorescent video microscopy imaging now allows the detailed observation and quantification of these events in live cells over time. Here we use these observations as a basis for building differential equation models of the transformations. An initial investigation of these interactions was modelled with reaction rates proportional to the sum of the concentrations of the individual constituents. A first order linear system for the concentrations results. The structure of the system enables analytical expressions to be obtained and the problem becomes one of determining the reaction rates which generate the observed data plots. We present results with reaction rates which capture the general behaviour of the reactions so that we now have a complete mathematical model of phosphoinositide transformations that fits the experimental observations. Some excellent fits are obtained with modulated exponential functions; however, these are not solutions of the linear system. The question arises as to how the model may be modified to obtain a system whose solution provides a more accurate fit.

Conceptualisation of articular cartilage as a giant reverse micelle: A hypothetical mechanism for joint biocushioning and lubrication

Phospholipid (PL) molecules form the main structure of the membrane that prevents the direct contact of opposing articular cartilage layers. In this paper we conceptualise articular cartilage as a giant reverse micelle (GRM) in which the highly hydrated three-dimensional network of phospholipids is electrically charged and able to resist compressive forces during joint movement, and hence loading. Using this hypothetical base, we describe a hydrophilic-hydrophilic (HL-HL) biopair model of joint lubrication by contacting cartilages, whose mechanism is reliant on lamellar cushioning. To demonstrate the viability of our concept, the electrokinetic properties of the membranous layer on the articular surface were determined by measuring via microelectrophoresis, the adsorption of ions H, OH, Na and Cl on phospholipid membrane of liposomes, leading to the calculation of the effective surface charge density. The surface charge density was found to be -0.08 ± 0.002 cm-2 (mean ± S.D.) for phospholipid membranes, in 0.155 M NaCl solution and physiological pH. This value was approximately five times less than that measured in 0.01 M NaCl. The addition of synovial fluid (SF) to the 0.155 M NaCl solution reduced the surface charge density by 30% which was attributed to the binding of synovial fluid macromolecules to the phospholipid membrane. Our experiments show that particles charge and interact strongly with the polar core of RM. We demonstrate that particles can have strong electrostatic interactions when ions and macromolecules are solubilized by reverse micelle (RM). Since ions are solubilized by reverse micelle, the surface entropy influences the change in the charge density of the phospholipid membrane on cartilage surfaces. Reverse micelles stabilize ions maintaining equilibrium, their surface charges contribute to the stability of particles, while providing additional screening for electrostatic processes. © 2008 Elsevier Ireland Ltd. All rights reserved.

Experimentally induced diesel engine injector faults and some preliminary acoustic emission signal observations

Diesel engine fuel injector faults can lead to reduced power, increased fuel consumption and greater exhaust emission levels and if left unchecked, can eventually lead to premature engine failure. This paper provides an overview of the Diesel, or compression ignition combustion process, and of the two basic fuel injector nozzle designs used in Diesel engines, namely, the pintle-type and hole-type nozzles. Also described are some common faults associated with these two types of fuel injector nozzles and the techniques previously used to experimentally simulate these faults. This paper also presents a recent experimental campaign undertaken using two different diesel engines whereby various fuel injector nozzle faults were induced into the engines. The first series of tests was undertaken using a turbo-charged 5.9 litre; Cummins Diesel engine whist the second series of tests was undertaken using a naturally aspirated 4 cylinder, 2.216 litre, Perkins Diesel engine. Data corresponding to different injector fault conditions was captured using in-cylinder pressure, and acoustic emission transducers along with both crank-angle encoder and top-dead centre reference signals. Using averaged in-cylinder pressure signals, it was possible to qualify the severity of the faults whilst averaged acoustic emission signals were in turn, used as the basis for wavelets decomposition. Initial observations from this signal decomposition are also presented and discussed.

Bending and bundling of metal-free vertically aligned ZnO nanowires due to electrostatic interaction

Bending and bundling was observed from vertically aligned arrays of ZnO nanowires with flat (0001) top surfaces, which were synthesized using a vapor-phase method without metal catalysts. Sufficient evidence was found to exclude electron-beam bombardment during scanning electron microscopy as a cause for bending and bundling. We attribute the bending and bundling to electrostatic interactions due to charged (0001) polar surfaces, and also discussed the threshold surface charge densities for the bending and bundling based on a simple cantilever-bending model. Some growth features were indicative of the operation of electrostatic interactions during the growth.

Physical characteristics of small ions and their interaction with ultrafine particles in the urban environment

In recent years, the effect of ions and ultrafine particles on ambient air quality and human health has been well documented, however, knowledge about their sources, concentrations and interactions within different types of urban environments remains limited. This thesis presents the results of numerous field studies aimed at quantifying variations in ion concentration with distance from the source, as well as identifying the dynamics of the particle ionisation processes which lead to the formation of charged particles in the air. In order to select the most appropriate measurement instruments and locations for the studies, a literature review was also conducted on studies that reported ion and ultrafine particle emissions from different sources in a typical urban environment. The initial study involved laboratory experiments on the attachment of ions to aerosols, so as to gain a better understanding of the interaction between ions and particles. This study determined the efficiency of corona ions at charging and removing particles from the air, as a function of different particle number and ion concentrations. The results showed that particle number loss was directly proportional to particle charge concentration, and that higher small ion concentrations led to higher particle deposition rates in all size ranges investigated. Nanoparticles were also observed to decrease with increasing particle charge concentration, due to their higher Brownian mobility and subsequent attachment to charged particles. Given that corona discharge from high voltage powerlines is considered one of the major ion sources in urban areas, a detailed study was then conducted under three parallel overhead powerlines, with a steady wind blowing in a perpendicular direction to the lines. The results showed that large sections of the lines did not produce any corona at all, while strong positive emissions were observed from discrete components such as a particular set of spacers on one of the lines. Measurements were also conducted at eight upwind and downwind points perpendicular to the powerlines, spanning a total distance of about 160m. The maximum positive small and large ion concentrations, and DC electric field were observed at a point 20 m downwind from the lines, with median values of 4.4×103 cm-3, 1.3×103 cm-3 and 530 V m-1, respectively. It was estimated that, at this point, less than 7% of the total number of particles was charged. The electrical parameters decreased steadily with increasing downwind distance from the lines but remained significantly higher than background levels at the limit of the measurements. Moreover, vehicles are one of the most prevalent ion and particle emitting sources in urban environments, and therefore, experiments were also conducted behind a motor vehicle exhaust pipe and near busy motorways, with the aim of quantifying small ion and particle charge concentration, as well as their distribution as a function of distance from the source. The study found that approximately equal numbers of positive and negative ions were observed in the vehicle exhaust plume, as well as near motorways, of which heavy duty vehicles were believed to be the main contributor. In addition, cluster ion concentration was observed to decrease rapidly within the first 10-15 m from the road and ion-ion recombination and ion-aerosol attachment were the most likely cause of ion depletion, rather than dilution and turbulence related processes. In addition to the above-mentioned dominant ion sources, other sources also exist within urban environments where intensive human activities take place. In this part of the study, airborne concentrations of small ions, particles and net particle charge were measured at 32 different outdoor sites in and around Brisbane, Australia, which were classified into seven different groups as follows: park, woodland, city centre, residential, freeway, powerlines and power substation. Whilst the study confirmed that powerlines, power substations and freeways were the main ion sources in an urban environment, it also suggested that not all powerlines emitted ions, only those with discrete corona discharge points. In addition to the main ion sources, higher ion concentrations were also observed environments affected by vehicle traffic and human activities, such as the city centre and residential areas. A considerable number of ions were also observed in a woodland area and it is still unclear if they were emitted directly from the trees, or if they originated from some other local source. Overall, it was found that different types of environments had different types of ion sources, which could be classified as unipolar or bipolar particle sources, as well as ion sources that co-exist with particle sources. In general, fewer small ions were observed at sites with co-existing sources, however particle charge was often higher due to the effect of ion-particle attachment. In summary, this study quantified ion concentrations in typical urban environments, identified major charge sources in urban areas, and determined the spatial dispersion of ions as a function of distance from the source, as well as their controlling factors. The study also presented ion-aerosol attachment efficiencies under high ion concentration conditions, both in the laboratory and in real outdoor environments. The outcomes of these studies addressed the aims of this work and advanced understanding of the charge status of aerosols in the urban environment.

Demanding a change : time to act on statutory demands

The statutory demand procedure has been a part of our corporate law from its earliest modern formulations and it has been suggested, albeit anecdotally, that under the current regime, it gives rise to more litigation than any other part of the Corporations Act. Despite this there has been a lack of consideration of the underlying policy behind the procedure in both the case law and literature; both of which are largely centred on the technical aspects of the process. The purpose of this article is to examine briefly the process of the statutory demand in the context of the current insolvency law in Australia. This paper argues that robust analysis of the statutory demand regime is overdue. The paper first sets out to discover if there is a policy justification for the process and to articulate what that may be. Second, it will briefly examine the current legislation and argue that the structure actually encourages litigation which is arguably undesirable in the context of insolvency. In particular we will ask if the current rigid legal regime is appropriate for dealing efficiently with the highly charged atmosphere of contested insolvency. Third, it will examine suggested reforms in this area as to whether they might be a way forward.

Corona ions from high-voltage power lines : nature of emission and dispersion

Positive and negative small ions, aerosol ion and number concentration and dc electric fields were monitored at an overhead high-voltage power line site. We show that the emission of corona ions was not spatially uniform along the lines and occurred from discrete components such as a particular set of spacers. Maximum ion concentrations and atmospheric dc electric fields were observed at a point 20 m downwind of the lines. It was estimated that less than 7% of the total number of aerosol particles was charged. The electrical parameters decreased steadily with further downwind distance but remained significantly higher than background.

Community participation in the development of digital radio : the Australian experience

The participation of the community broadcasting sector in the development of digital radio provides a potentially valuable opportunity for non-market, end user-driven experimentation in the development of these new services in Australia. However this development path is constrained by various factors, some of which are specific to the community broadcasting sector and others that are generic to the broader media and communications policy, industrial and technological context. This paper filters recent developments in digital radio policy and implementation through the perspectives of community radio stakeholders, obtained through interviews, to describe and analyse these constraints. The early stage of digital community radio presented here is intended as a baseline for tracking the development of the sector as digital radio broadcasting develops. We also draw upon insights from scholarly debates about citizens media and participatory culture to identify and discuss two sets of opportunities for social benefit that are enabled by the inclusion of community radio in digital radio service development. The first arises from community broadcasting’s involvement in the propagation of the multi-literacies that drive new digital economies, not only through formal and informal multi- and trans-media training, but also in the ‘co-creative’ forms of collaborative and participatory media production that are fostered in the sector. The second arises from the fact that community radio is uniquely placed — indeed charged with the responsibility — to facilitate social participation in the design and operation of media institutions themselves, not just their service outputs.

Advance pricing arrangements : an Australian Tax Office success or a legislative failure?

Australia’s domestic income tax legislation and double tax agreements contain transfer pricing rules which are designed to counter the underpayment of tax by businesses engaged in international dealings between related parties. The current legislation and agreements require that related party transactions take place at a value which reflects an arm’s length price, that is, a price which would be charged between unrelated parties. For a host of reasons, it is increasingly difficult for multinational entities to demonstrate that they are transferring goods and services at a price which is reflective of the behaviour of independent parties, thereby making it difficult to demonstrate compliance with the relevant legislation. Further, where an Australian business undertakes cross-border related party transactions there is the risk of an audit by the Australian Tax Office (ATO). If a business wishes to avoid the risk of an audit, and any ensuing penalties, there is one option: an advance pricing arrangement (APA). An APA is an agreement whereby the future transfer pricing methodology to be used to determine the arm’s length price is agreed to by the taxpayer and the relevant tax authority or authorities. The ATO views the APA process as an important part of its international tax strategy and believes that there are complementary benefits provided to both the taxpayer and the ATO. The ATO promotes the APA process on the basis of creating greater certainty for all parties while reducing compliance costs and the risk of audit and penalty. While the ATO regards the APA system as a success, it may be argued that the implementation of such a system is simply a practical solution to an ongoing problem of an inherent failure in both the legislation and ATO interpretation and application of this legislation to provide certainty to the taxpayer. This paper investigates the use of APAs as a solution to the problem of transfer pricing and considers whether they are the success the ATO claims. It is argued that there is no doubt that APAs provide a valuable practical tool for multinational entities facing the challenges of the taxation of global trading under the current transfer pricing regime. It does not, however, provide a long term solution. Rather, the long term solution may be in the form of legislative amendment.

Regulating the cost of small loans : overdue or overkill?

Small-amount short-term lending began in 1994 in response to the initial exemption of such loans from consumer credit regulation. Growing demand for such loans now produces industry turnover of approximately $800 million each year. Regulators recognised early the need for consumer protection due to the vulnerability of borrowers and the emergence of various predatory practices. This led to reforms designed to regulate these loans, prevent particular misconduct and provide remedies against injustice. Some were enacted as part of the National Consumer Credit Protection Act 2009 (Cth), which also imposed licensing and responsible lending requirements on lenders and increased consumer access to remedies. The Government has now introduced the Consumer Credit and Corporations Amendment (Enhancements) Bill 2011 which limits the price that can be charged for credit and restricts access to small loans. This article examines the extensive reforms which have taken place in this sector, and compares these regulatory approaches with the “bright line approach” of the Enhancements Bill. The article argues that the repercussions of this step will require careful monitoring to ensure that further harm is not suffered by those least able to bear it, and that the government will also need to facilitate other, more sustainable, solutions to the problem that small loans are currently used to solve. After we wrote this article, the Report of the Parliamentary Joint Committee on Corporations and Financial Services and the Report of the Senate Economics Legislation Committee on the Enhancements Bill were released. These are referred to in a postscript.

Analysis and correction of voltage profile in low voltage distribution networks containing photovoltaic cells and electric vehicles

Voltage drop and rise at network peak and off–peak periods along with voltage unbalance are the major power quality problems in low voltage distribution networks. Usually, the utilities try to use adjusting the transformer tap changers as a solution for the voltage drop. They also try to distribute the loads equally as a solution for network voltage unbalance problem. On the other hand, the ever increasing energy demand, along with the necessity of cost reduction and higher reliability requirements, are driving the modern power systems towards Distributed Generation (DG) units. This can be in the form of small rooftop photovoltaic cells (PV), Plug–in Electric Vehicles (PEVs) or Micro Grids (MGs). Rooftop PVs, typically with power levels ranging from 1–5 kW installed by the householders are gaining popularity due to their financial benefits for the householders. Also PEVs will be soon emerged in residential distribution networks which behave as a huge residential load when they are being charged while in their later generation, they are also expected to support the network as small DG units which transfer the energy stored in their battery into grid. Furthermore, the MG which is a cluster of loads and several DG units such as diesel generators, PVs, fuel cells and batteries are recently introduced to distribution networks. The voltage unbalance in the network can be increased due to the uncertainties in the random connection point of the PVs and PEVs to the network, their nominal capacity and time of operation. Therefore, it is of high interest to investigate the voltage unbalance in these networks as the result of MGs, PVs and PEVs integration to low voltage networks. In addition, the network might experience non–standard voltage drop due to high penetration of PEVs, being charged at night periods, or non–standard voltage rise due to high penetration of PVs and PEVs generating electricity back into the grid in the network off–peak periods. In this thesis, a voltage unbalance sensitivity analysis and stochastic evaluation is carried out for PVs installed by the householders versus their installation point, their nominal capacity and penetration level as different uncertainties. A similar analysis is carried out for PEVs penetration in the network working in two different modes: Grid to vehicle and Vehicle to grid. Furthermore, the conventional methods are discussed for improving the voltage unbalance within these networks. This is later continued by proposing new and efficient improvement methods for voltage profile improvement at network peak and off–peak periods and voltage unbalance reduction. In addition, voltage unbalance reduction is investigated for MGs and new improvement methods are proposed and applied for the MG test bed, planned to be established at Queensland University of Technology (QUT). MATLAB and PSCAD/EMTDC simulation softwares are used for verification of the analyses and the proposals.

A review of system safety failure probability objectives for Unmanned Aircraft Systems

Unmanned Aircraft Systems (UAS) are one of a number of emerging aviation sectors. Such new aviation concepts present a significant challenge to National Aviation Authorities (NAAs) charged with ensuring the safety of their operation within the existing airspace system. There is significant heritage in the existing body of aviation safety regulations for Conventionally Piloted Aircraft (CPA). It can be argued that the promulgation of these regulations has delivered a level of safety tolerable to society, thus justifying the “default position” of applying these same standards, regulations and regulatory structures to emerging aviation concepts such as UAS. An example of this is the proposed “1309” regulation for UAS, which is based on the 1309 regulation for CPA. However, the absence of a pilot on-board an unmanned aircraft creates a fundamentally different risk paradigm to that of CPA. An appreciation of these differences is essential to the justification of the “default position” and in turn, to ensure the development of effective safety standards and regulations for UAS. This paper explores the suitability of the proposed “1309” regulation for UAS. A detailed review of the proposed regulation is provided and a number of key assumptions are identified and discussed. A high-level model characterising the expected number of third party fatalities on the ground is then used to determine the impact of these assumptions. The results clearly show that the “one size fits all” approach to the definition of 1309 regulations for UAS, which mandates equipment design and installation requirements independent of where the UAS is to be operated, will not lead to an effective management of the risks.

The Industry Commission inquiry into charitable organisations : the draft report implications for the future of community services

In December 1993, the Commonwealth Assistant Treasurer., Mr George Gear announced an Inquiry into Charitable Organisations in Australia. The inquiry would be undertaken by the Industry Commission, the structure charged by the Commonwealth to oversight its micro-economic reform agenda. The inquiry had been on the Industry Commission's forward workplan since 1992. In July 1993 a draft terms of reference was prepared for comment by the State Premiers...

The geostationary orbit : a critical legal geography of space’s most valuable real estate

This chapter attends to the legal and political geographies of one of Earth's most important, valuable, and pressured spaces: the geostationary orbit. Since the first, NASA, satellite entered it in 1964, this small, defined band of Outer Space, 35,786km from the Earth's surface, and only 30km wide, has become a highly charged legal and geopolitical environment, yet it remains a space which is curiously unheard of outside of specialist circles. For the thousands of satellites which now underpin the Earth's communication, media, and data industries and flows, the geostationary orbit is the prime position in Space. The geostationary orbit only has the physical capacity to hold approximately 1500 satellites; in 1997 there were approximately 1000. It is no overstatement to assert that media, communication, and data industries would not be what they are today if it was not for the geostationary orbit. This chapter provides a critical legal geography of the geostationary orbit, charting the topography of the debates and struggles to define and manage this highly-important space. Drawing on key legal documents such as the Outer Space Treaty and the Moon Treaty, the chapter addresses fundamental questions about the legal geography of the orbit, questions which are of growing importance as the orbit’s available satellite spaces diminish and the orbit comes under increasing pressure. Who owns the geostationary orbit? Who, and whose rules, govern what may or may not (literally) take place within it? Who decides which satellites can occupy the orbit? Is the geostationary orbit the sovereign property of the equatorial states it supertends, as these states argued in the 1970s? Or is it a part of the res communis, or common property of humanity, which currently legally characterises Outer Space? As challenges to the existing legal spatiality of the orbit from launch states, companies, and potential launch states, it is particularly critical that the current spatiality of the orbit is understood and considered. One of the busiest areas of Outer Space’s spatiality is international territorial law. Mentions of Space law tend to evoke incredulity and ‘little green men’ jokes, but as Space becomes busier and busier, international Space law is growing in complexity and importance. The chapter draws on two key fields of research: cultural geography, and critical legal geography. The chapter is framed by the cultural geographical concept of ‘spatiality’, a term which signals the multiple and dynamic nature of geographical space. As spatial theorists such as Henri Lefebvre assert, a space is never simply physical; rather, any space is always a jostling composite of material, imagined, and practiced geographies (Lefebvre 1991). The ways in which a culture perceives, represents, and legislates that space are as constitutive of its identity--its spatiality--as the physical topography of the ground itself. The second field in which this chapter is situated—critical legal geography—derives from cultural geography’s focus on the cultural construction of spatiality. In his Law, Space and the Geographies of Power (1994), Nicholas Blomley asserts that analyses of territorial law largely neglect the spatial dimension of their investigations; rather than seeing the law as a force that produces specific kinds of spaces, they tend to position space as a neutral, universally-legible entity which is neatly governed by the equally neutral 'external variable' of territorial law (28). 'In the hegemonic conception of the law,' Pue similarly argues, 'the entire world is transmuted into one vast isotropic surface' (1990: 568) on which law simply acts. But as the emerging field of critical legal geography demonstrates, law is not a neutral organiser of space, but is instead a powerful cultural technology of spatial production. Or as Delaney states, legal debates are “episodes in the social production of space” (2001, p. 494). International territorial law, in other words, makes space, and does not simply govern it. Drawing on these tenets of the field of critical legal geography, as well as on Lefebvrian concept of multipartite spatiality, this chapter does two things. First, it extends the field of critical legal geography into Space, a domain with which the field has yet to substantially engage. Second, it demonstrates that the legal spatiality of the geostationary orbit is both complex and contested, and argues that it is crucial that we understand this dynamic legal space on which the Earth’s communications systems rely.

Travel behavior of workers in Dhaka and their attitude towards road pricing

Dhaka, the capital of Bangladesh, is facing severe traffic congestion. Owing to the flaws in past land use and transport planning decisions, uncontrolled population growth and urbanization, Dhaka’s traffic condition is worsening. Road space is widely regarded in the literature as a utility, so a common view of transport economists is that its usage ought to be charged. Road pricing policy has proven to be effective in managing travel demand, in order to reduce traffic congestion from road networks in a number of cities including London, Stockholm and Singapore. Road pricing as an economic mechanism to manage travel demand can be more effective and user-friendly when revenue is hypothecated into supply alternatives such as improvements to the transit system. This research investigates the feasibility of adopting road pricing in Dhaka with respect to a significant Bus Rapid Transit (BRT) project. Because both are very new concepts for the population of Dhaka, public acceptability would be a principal issue driving their success or failure. This paper explores the travel behaviour of workers in Dhaka and public perception toward Road Pricing with regards to work trips- based on worker’s travel behaviour. A revealed preference and stated preference survey has been conducted on sample of workers in Dhaka. They were asked limited demographic questions, their current travel behaviour and at the end they had been given several hypothetical choices of integrated BRT and road pricing to choose from. Key finding from the survey is the objective of integrated road pricing; subsidies Bus rapid Transit by road pricing to get reduced BRT fare; cannot be achieved in Dhaka. This is because most of the respondent stated that they would choose the cheapest option Walk-BRT-Walk, even though this would be more time consuming and uncomfortable as they have to walk from home to BRT station and also from BRT station to home. Proper economic analysis has to be carried out to find out the appropriate fare of BRT and road charge with some incentive for the low income people.