Time-dependent reflection at the localization transition

A short quasi-monochromatic wave packet incident on a semi-infinite disordered medium gives rise to a reflected wave. The intensity of the latter decays as a power law $1/t^{\alpha}$ in the long-time limit. Using the one-dimensional Aubry-Andr\'{e} model, we show that in the vicinity of the critical point of Anderson localization transition, the decay slows down and the power-law exponent $\alpha$ becomes smaller than both $\alpha = 2$ found in the Anderson localization regime and $\alpha = 3/2$ expected for a one-dimensional random walk of classical particles.Comment: 9 pages, 6 figures. Revised tex

Robust Emergent Activity in Dynamical Networks

We study the evolution of a random weighted network with complex nonlinear dynamics at each node, whose activity may cease as a result of interactions with other nodes. Starting from a knowledge of the micro-level behaviour at each node, we develop a macroscopic description of the system in terms of the statistical features of the subnetwork of active nodes. We find the asymptotic characteristics of this subnetwork to be remarkably robust: the size of the active set is independent of the total number of nodes in the network, and the average degree of the active nodes is independent of both the network size and its connectivity. These results suggest that very different networks evolve to active subnetworks with the same characteristic features. This has strong implications for dynamical networks observed in the natural world, notably the existence of a characteristic range of links per species across ecological systems.Comment: 4 pages, 5 figure

Experimental Study of Electrophoretic Deposited Carbon Nanotubes on Microstrip Transmission Line Resonators and Filters

The electrical properties of single-walled carbon nanotube electrophoreses deposition on different types of gold-plated microstrip devices are investigated. Simple transmission lines, transmission line resonators and filters were subjected to deposition of functionalized tubes in an aqueous solution. It is found that the process lowers the resonant frequency of the resonators and filters compared to the untreated devices, at the cost of increased insertion loss and reduced resonator Q-factor

Coupled Ocean Atmosphere Processes and European Climate (COAPEC): improved understanding of the coupled climate system

COAPEC (http://coapec.nerc.ac.uk/) is a five-year Directed Science Programme funded by the Natural Environment Research Council (NERC). COAPEC is providing advances in understanding the mechanisms by which the ocean and atmosphere interact, how these processes are represented in state-of-the-art numerical climate models and how they determine the predictability of the climate system over seasonal-decadal timescales. Processes studied include the generation and propagation of salinity and heat anomalies in the North Atlantic, the influence of the thermohaline circulation and the role of storm tracks on European Climate. The influence of remote processes, including ocean-atmosphere coupling in tropical Atlantic warm events and Southern Ocean circulation are also being investigated. As part of the programme, new coupled models are being developed, including: a coupled hybrid isopycnic coordinate model; fast models for multi-ensemble runs to investigate model parameters space, using both high performance machines and spare home PC resources; a QG model to investigate high resolution ocean processes in coupled systems and validated ice models for coupled modelling. Underpinning research into improving the observational datasets, such as the SOC flux climatology, and into the influence of sea-ice observations in General Circulation Models is also being carried out as part of the programme. To place these advances into a socially relevant context, COAPEC is also investigating the methods for using, and economic benefits of, climate forecasts at seasonal timescales for the UK health sector and the UK energy industry

Spectral Red-Shift Versus Broadening from Photon and Dilepton Spectra

We estimate the photon and dilepton emission rates from hot hadronic matter with in-medium spectral shift and broadening of vector mesons. It is observed that both the WA98 photon data and CERES/NA45 dilepton data can be well reproduced with similar initial conditions. The freeze-out condition has been constrained by the transverse mass spectra of pions and protons measured by the NA49 collaboration. We argue that simultaneous measurement of the $p_T$ spectra of single photons as well as invariant mass distribution of dileptons is crucial to understand the in-medium spectral function of the vector mesons.Comment: Title and contents change

Verification and transfer of thermal pollution model. Volume 4: User's manual for three-dimensional rigid-lid model

The theory of a three dimensional (3-D) mathematical thermal discharge model and a related one dimensional (1-D) model are described. Model verification at two sites, a separate user's manual for each model are included. The 3-D model has two forms: free surface and rigid lid. The former allows a free air/water interface and is suited for significant surface wave heights compared to mean water depth, estuaries and coastal regions. The latter is suited for small surface wave heights compared to depth because surface elevation was removed as a parameter. These models allow computation of time dependent velocity and temperature fields for given initial conditions and time-varying boundary conditions. The free surface model also provides surface height variations with time

Quantum Noise and Fluctuations in Gravitation and Cosmology

We give a short update of our research program on nonequilibrium statistical field theory applied to quantum processes in the early universe and black holes, as well as the development of stochastic gravity theory as an extension of semiclassical gravity and an intermediary in the 'bottom-up' approach to quantum gravity.Comment: 16 pages Latex; small changes in a couple of footnote