Avian retinal oil droplets : dietary manipulation of colour vision?

Avian vision is highly developed, with bird retinas containing rod and double-cone photoreceptors, plus four classes of single cones subserving tetrachromatic colour vision. Cones contain an oil droplet, rich in carotenoid pigments (except VS/ultraviolet-sensitive cones), that acts as a filter, substantially modifying light detected by the photoreceptor. Using dietary manipulations, we tested the effects of carotenoid availability on oil droplet absorbance properties in two species: Platycercus elegans and Taeniopygia guttata. Using microspectrophotometry, we determined whether manipulations affected oil droplet carotenoid concentration and whether changes would alter colour discrimination ability. In both species, increases in carotenoid concentration were found in carotenoid-supplemented birds, but only in the double cones. Magnitudes of effects of manipulations were often dependent on retinal location. The study provides, to our knowledge, the first experimental evidence of dietary intake over a short time period affecting carotenoid concentration of retinal oil droplets. Moreover, the allocation of carotenoids to the retina by both species is such that the change potentially preserves the spectral tuning of colour vision. Our study generates new insights into retinal regulation of carotenoid concentration of oil droplets, an area about which very little is known, with implications for our understanding of trade-offs in carotenoid allocation in birds.

Incorporating design explanation within formal object-oriented method (FOOM)

Requirements engineering is a commencing phase in the development of either software applications or information systems. It is concerned with understanding and specifying the customer's requirements of the system to be delivered. Throughout the literature, this is agreed to be one of the most crucial and, unfortunately, problematic phases in development. Despite the diversity of research directions, approaches and methods, the question of process understanding and management is still limited. Among contemporary approaches to the improvement of the current practice of Requirements Engineering, Formal Object-Oriented Method (FOOM) has been introduced as a new promising solution. The FOOM approach to requirements engineering is based on a synthesis of socio-organisational theory, the object-oriented approach, and mathematical formal specification. The entire FOOM specification process is evolutionary and involves a large volume of changes in requirements. During this process, requirements evolve through various forms of informal, semi-formal, and formal while maintaining a semantic link between these forms and, most importantly, conforming to the customer's requirements. A deep understanding of the complexity of the requirements model and its dynamics is critical in improving requirements engineering process management. This thesis investigates the benefits of documenting both the evolution of the requirements model and the rationale for that evolution. Design explanation explains and justifies the deliberations of, and decisions made during, the design activity. In this thesis, design explanation is used to describe the requirements engineering process in order to improve understandability of, and traceability within, the evolving requirements specification. The design explanation recorded during this research project is also useful in assisting the researcher in gaining insights into the creativity and opportunistic characteristics of the requirements engineering process. This thesis offers an interpretive investigation into incorporating design explanation within FOOM in order to extend and advantage the method. The researcher's interpretation and analysis of collected data highlight an insight-driven and opportunistic process rather than a strictly and systematically predefined one. In fact, the process was not smoothly evolutionary, but involved occasional 'crisis' points at which the model was reconceptualised, simplified and restructured. Therefore, contributions of the thesis lie not only in an effective incorporation of design explanation within FOOM, but also a deep understanding of the dynamic process of requirements engineering. The new understanding of the complexity of the requirements model and its dynamics suggests new directions for future research and forms a basis for a new approach to process management.

Strategic vote manipulation in a simple democracy

In both the Employee Stock Ownership Plan (ESOP) and employee buyouts, the common and crucial phenomenon is that some workers have two sources of income, namely wages and shares of profit. We analyze that phenomenon in an economy where workers are nonunionized and wages are determined by voting. If the employers sell a certain amount of shares of the capital stock to some non-risk-loving workers, these workers vote for the lowest possible wage along with the employers. As a result, all workers become equally worse off because of the competition among workers to buy those shares.

Magnetic liquid marbles : manipulation of liquid droplets using highly hydrophobic Fe3O4 nanoparticles

Magnetic liquid marbles exhibit a remarkable ability to be opened and closed reversibly under the action of a magnetic field. Liquid can be either extracted from or added to the opened liquid marble simply with a capillary needle. Two opened liquid marbles can also be coalesced into a larger one. The magnetic liquid marbles can be maneuvered two- and three-dimensionally.

Computational simulation of gas flow and heat transfer near immersed object in fluidised bed

To improve the understanding of the heat transfer mechanism and find a reliable and simple heat-transfer model, the gas flow and heat transfer between fluidised beds and immersed object surfaces was numerically simulated based on a double particlelayer and porous medium model. The velocity field and temperature distribution of gas were discussed to analyse the heat transfer process.

On the simultaneous estimation of optical flow and object state

This thesis focuses on the enhancement of differential optical flow techniques. The framwork of differential optical flow has been built upon to improve object motion estimation within a video stream or image sequence. This augmentation comes in the form of a combined optical flow and object state estimation method (SEOS)

Prototyping real-time systems using Petri net and object-oriented models

The objective of the research for this thesis is to develop techniques in order to build an executable model of a real-time system. This model is to be used early in the development of the system not only to detect errors in the specification of the system but also to validate expectations of the developer as to the operation of the system. A graphical specification of a real-time system called the transformation schema was chosen to be used to build the model. Two executable models of a real-time system are described.

The roles of object-image relative motion and static depth information in the perception of heading

Investigates visual information that enables human to effectively guide their movement through the environment. This problem is fundamental to the study of human behaviour, since survival is contingent upon the acquisition of resources that lie in different locations throughout the environment.

Dielectrophoretic manipulation and separation of microparticles using curved microelectrodes

This paper presents the development and experimental analysis of a dielectrophoresis (DEP) system, which is used for the manipulation and separation of microparticles in liquid flow. The system is composed of arrays of microelectrodes integrated to a microchannel. Novel curved microelectrodes are symmetrically placed with respect to the centre of the microchannel with a minimum gap of 40 mm. Computational fluid dynamics method is utilised to characterise the DEP field and predict the dynamics of particles. The performance of the system is assessed with microspheres of 1, 5 and 12 mm diameters. When a high-frequency potential is applied to microelectrodes a spatially varying electric field is induced in the microchannel, which creates the DEP force. Negative-DEP behaviour is observed with particles being repelled from the microelectrodes. The particles of different dimensions experience different DEP forces and thus settle to separate equilibrium zones across the microchannel. Experiments demonstrate the capability of the system as a field flow fraction tool for sorting microparticles according to their dimensions and dielectric properties.

Dielectrophoresis for manipulation of micro/nano particles in microfluidic systems

Dielectrophoretic (DEP) force is exerted when a neutral particle is polarized in a non-uniform electric field, and depends on the dielectric properties of the particle and the suspending medium. The integration of DEP and microfluidic systems offers numerous applications for the separation, trapping, assembling, transportation, and characterization of micro/nano particles. This article reviews the applications of DEP forces in microfluidic systems. It presents the theory of dielectrophoresis, different configurations, and the applications of such systems for particle manipulation and device fabrication.