A vehicular ad hoc network (VANET) is a mobile ad hoc network (MANET) in which network nodes are vehicles -most commonly road vehicles. VANETs present a unique range of challenges and opportunities for routing protocols due to the semi-organised nature of vehicular movements subject to the constraints of road geometry and rules, and the obstacles which limit physical connectivity in urban environments. In particular, the problems of routing protocol reliability and scalability across large urban VANETs are currently the subject of intense research. Clustering can be used to improve routing scalability and reliability in VANETs, as it results in the distributed formation of hierarchical network structures by grouping vehicles together based on correlated spatial distribution and relative velocity. In addition to the benefits to routing, these groups can serve as the foundation for accident or congestion detection, inforomation dissemination and entertainment applications. This paper explores the design choices made in the development of clustering algorithms targeted at VANETs. It presents a taxonomy of the techniques applied to solve the problems of cluster head election, cluster affiliation and cluster management, and identifies new directions and recent trends in the design of these algorithms. Additionally, methodologies for validating clustering performance are reviewed, and a key shortcomingthe lack of realistic vehicular channel modelling -is identified. The importance of a rigorous and standardised performance evaluation regime utilising realistic vehicular channel models is demonstrated.

This paper presents Neutron Capture Enhanced Particle Therapy (NCEPT), a method for enhancing the radiation dose delivered to a tumour relative to surrounding healthy tissues during proton and carbon ion therapy by capturing thermal neutrons produced inside the treatment volume during irradiation. NCEPT utilises extant and in-development boron-10 and gadolinium-157-based drugs from the related field of neutron capture therapy. Using Monte Carlo simulations, we demonstrate that a typical proton or carbon ion therapy treatment plan generates an approximately uniform thermal neutron field within the target volume, centred around the beam path. The tissue concentrations of neutron capture agents required to obtain an arbitrary 10% increase in biological effective dose are estimated for realistic treatment plans, and compared to concentrations previously reported in the literature. We conclude that the proposed method is theoretically feasible, and can provide a worthwhile improvement in the dose delivered to the tumour relative to healthy tissue with readily achievable concentrations of neutron capture enhancement drugs.

The prototype of HDR BrachyView demonstrates a satisfactory level of accuracy in its source position estimation, and additional improvements are achievable with further refinement of HDR BrachyView's image processing algorithms.

Ferromagnetic resonance measurements were made as a function of the static external field angle for c-plane disks of single crystal flux grown manganese substituted barium M-type ͑Ba-M ͒ and zinc Y-type ͑Zn-Y ͒ hexagonal ferrites at 50 and 8.8 GHz, respectively. A shorted waveguide technique was used. Analysis of the FMR field versus angle results confirmed the operational assumption of a uniform mode response. For the easy-axis Ba-M disk, the linewidth was 69 Oe when the external field and magnetization vectors were perpendicular to the disk. The linewidth increased to a maximum measured value of 472 Oe when the magnetization was directed 45.4°from the sample normal. For the easy-plane Zn-Y disk, the linewidth had a minimum value of 18 Oe when the field and magnetization vectors were in-plane. The maximum linewidth was 391 Oe when the magnetization was directed 25.2°from the disk normal. The linewidths were larger than predicted for reasonable values of the Landau-Lifshitz damping and showed angle dependences which indicated nonintrinsic contributions to the loss. A modified two magnon scattering calculation based on the model of Sparks, Loudon, and Kittel was used to investigate these linewidth differences. The calculation included anisotropy modifications to the spin wave band for each material. The angle dependences of the excess linewidths show qualitative agreement with the two magnon predictions, with inhomogeneity sizes on the order of 1 and 0.25 m and volume fractions of 0.01 and 0.005 for the Ba-M and Zn-Y disks, respectively.

Comparative study of alternative Geant4 hadronic ion inelastic physics models Comparative study of alternative Geant4 hadronic ion inelastic physics models for prediction of positron-emitting radionuclide production in carbon and oxygen for prediction of positron-emitting radionuclide production in carbon and oxygen ion therapy ion therapy