A treatise on analytical geometry of three dimensions : containing the theory of curve surfaces and of curves of double curvature /

Mode of access: Internet.

The effects of J-gate potential and interfaces on donor exchange coupling in the Kane quantum computer architecture

We calculate the electron exchange coupling for a phosphorus donor pair in silicon perturbed by a J-gate potential and the boundary effects of the silicon host geometry. In addition to the electron-electron exchange interaction we also calculate the contact hyperfine interaction between the donor nucleus and electron as a function of the varying experimental conditions. Donor separation, depth of the P nuclei below the silicon oxide layer and J-gate voltage become decisive factors in determining the strength of both the exchange coupling and hyperfine interaction-both crucial components for qubit operations in the Kane quantum computer. These calculations were performed using an anisotropic effective-mass Hamiltonian approach. The behaviour of the donor exchange coupling as a function of the parameters varied in this work provides relevant information for the experimental design of these devices.

Cells, surfaces and adhesion

This thesis concerns cell adhesion to polymer surfaces with an experimental emphasis on hydrogels. The thesis begins with a review of the literature and a synthesis of recent evidence to describe the process of cell adhesion in a given situation. The importance of understanding integrin-adhesion protein interactions and adhesion protein-surface interactions is emphasised. The experimental chapters describe three areas of investigation. Firstly, in vitro cell culture techniques are used to explore a variety of surfaces including polyethylene glycol methacrylate (PEGMA) substituted hydrogels, sequence distribution modified hydrogels and worn contact lenses. Cell adhesion to PEGMA substituted gels is found to decrease with increases in polyethylene oxide chain length and correlations are made between sequence distribution and adhesion. Worn contact lenses are investigated for their cell adhesion properties in the presence of antibodies to specific adhesion proteins, demonstrating the presence of vitronectin and fibronectin on the lenses. The second experimental chapter addresses divalent cation regulation of integrin mediated cell adhesion. Several cell types and various cations are used. Zinc, previously not regarded as an important cation in the process, is found to inhibit 3T3 cell adhesion to vitronectin that is promoted by other divalent cations. The final experimental chapter concerns cell adhesion and growth on macroporous hydrogels. A variety of freeze-thaw formed porous gels are investiated and found generally to promote cell growth rate.Interpenetrating networkbased gels (IPN) are made porous by elution of dextrin particles of varying size and loading density. These materials provide the basis for synthetic cartilage. Cartilage cells (chondrocytes) plated onto the surface of the porous IPN materials maintain a rounded shape and hence phenotypic function when a critical pore size and density is achieved. In this way, a prospective implant, made porous at the perpendicular edges contacting natural cartilage can be both mechanically stabilised and encourage the maintenance of normal matrix production at the tissue interface.

Fluctuations and correlations in sandpiles and interfaces with boundary pinning

Interfaces are studied in an inhomogeneous critical state where boundary pinning is compensated with a ramped force. Sandpiles driven off the self-organized critical point provide an example of this ensemble in the Edwards-Wilkinson (EW) model of kinetic roughening. A crossover from quenched to thermal noise violates spatial and temporal translational invariances. The bulk temporal correlation functions have the effective exponents β1D∼0.88±0.03 and β2D∼0.52±0.05, while at the boundaries βb,1D/2D∼0.47±0.05. The bulk β1D is shown to be reproduced in a randomly kicked thermal EW model.

Fluctuations and correlations in sandpiles and interfaces with boundary pinning

Interfaces are studied in an inhomogeneous critical state where boundary pinning is compensated with a ramped force. Sandpiles driven off the self-organized critical point provide an example of this ensemble in the Edwards-Wilkinson (EW) model of kinetic roughening. A crossover from quenched to thermal noise violates spatial and temporal translational invariances. The bulk temporal correlation functions have the effective exponents β1D∼0.88±0.03 and β2D∼0.52±0.05, while at the boundaries βb,1D/2D∼0.47±0.05. The bulk β1D is shown to be reproduced in a randomly kicked thermal EW model.

Equimultiple Locus of Embedded Algebroid Surfaces and Blowing–up in Characteristic Zero

2000 Mathematics Subject Classification: 14B05, 32S25.

Nanoscratch and nanowear testing of TiN coatings on M42 steel

Constant load, progressive load and multipass nanoscratch (nanowear) tests were carried out on 500 and 1500 nm TiN coatings on M42 steel chosen as model systems. The influences of film thickness, coating roughness, scratch direction relative to the grinding grooves on the critical load in the progressive load test and number of cycles to failure in the wear test have been determined. Progress towards the development of a suitable methodology for determining the scratch hardness from nanoscratch tests is discussed. © 2011 W. S. Maney & Son Ltd.

The optical response of nanostructured surfaces and the composite diffracted evanescent wave model

Investigations of the optical response of subwavelength-structure arrays milled into thin metal films have revealed surprising phenomena, including reports of unexpectedly high transmission of light. Many studies have interpreted the optical coupling to the surface in terms of the resonant excitation of surface plasmon polaritons (SPPs), but other approaches involving composite diffraction of surface evanescent waves (CDEW) have also been proposed. Here we present a series of measurements on very simple one-dimensional subwavelength structures to test the key properties of the surface waves, and compare them to the CDEW and SPP models. We find that the optical response of the silver metal surface proceeds in two steps: a diffractive perturbation in the immediate vicinity (2–3 mu m) of the structure, followed by excitation of a persistent surface wave that propagates over tens of micrometres. The measured wavelength and phase of this persistent wave are significantly shifted from those expected for resonance excitation of a conventional SPP on a pure silver surface.

Analysis of Automotive Cybersecurity - Attack surfaces and users’ privacy concerns

Modern automobiles are no longer just mechanical tools. The electronics and computing services they are shipping with are making them not less than a computer. They are massive kinetic devices with sophisticated computing power. Most of the modern vehicles are made with the added connectivity in mind which may be vulnerable to outside attack. Researchers have shown that it is possible to infiltrate into a vehicle’s internal system remotely and control the physical entities such as steering and brakes. It is quite possible to experience such attacks on a moving vehicle and unable to use the controls. These massive connected computers can be life threatening as they are related to everyday lifestyle. First part of this research studied the attack surfaces in the automotive cybersecurity domain. It also illustrated the attack methods and capabilities of the damages. Online survey has been deployed as data collection tool to learn about the consumers’ usage of such vulnerable automotive services. The second part of the research portrayed the consumers’ privacy in automotive world. It has been found that almost hundred percent of modern vehicles has the capabilities to send vehicle diagnostic data as well as user generated data to their manufacturers, and almost thirty five percent automotive companies are collecting them already. Internet privacy has been studies before in many related domain but no privacy scale were matched for automotive consumers. It created the research gap and motivation for this thesis. A study has been performed to use well established consumers privacy scale – IUIPC to match with the automotive consumers’ privacy situation. Hypotheses were developed based on the IUIPC model for internet consumers’ privacy and they were studied by the finding from the data collection methods. Based on the key findings of the research, all the hypotheses were accepted and hence it is found that automotive consumers’ privacy did follow the IUIPC model under certain conditions. It is also found that a majority of automotive consumers use the services and devices that are vulnerable and prone to cyber-attacks. It is also established that there is a market for automotive cybersecurity services and consumers are willing to pay certain fees to avail that.

Microstructural evolution of tungsten oxide thin films

Tungsten oxide thin films are of great interest due to their promising applications in various optoelectronic thin film devices. We have investigated the microstructural evolution of tungsten oxide thin films grown by DC magnetron sputtering on silicon substrate. The structural characterization and surface morphology were carried out using X-ray diffraction and Scanning Electron Microscopy (SEM). The as deposited films were amorphous, where as, thin films annealed above 400 degrees C were crystalline. In order to explain the microstructural changes due to annealing, we have proposed a ``instability wheel'' model for the evolution of the microstructure. This model explains the transformation of mater into various geometries within them selves, followed by external perturbation.

Towards the identification of the common features of bacterial biofilm development

UPNa. Instituto de Agrobiotecnología. Laboratorio de Biofilms Microbianos