Stimulated Raman and Brillouin backscattering of collimated beams carrying orbital angular momentum.

We study theoretically the exchange of angular momentum between electromagnetic and electrostatic waves in a plasma, due to the stimulated Raman and Brillouin backscattering processes. Angular momentum states for plasmon and phonon fields are introduced for the first time. We demonstrate that these states can be excited by nonlinear wave mixing, associated with the scattering processes. This could be relevant for plasma diagnostics, both in laboratory and in space. Nonlinearly coupled paraxial equations and instability growth rates are derived.

Cardiovascular diagnostics mining on Borneo island: from labour-intensive to prototype.

Mining for medical data poses different challenges compared with mining other types of data. The wide range of imaging modalities of medical data leads to data integration and compatibility issues. The analysis of imaging modalities is further complicated by the different format and attributes used by the different imaging equipment by different vendors. Human factors such as interest of adapting data mining into diagnosis and planning process raised the difficulty of engaging the users into the development of a practical and useful data miner. Requirement engineering technique prototyping further enhanced the engagement of users towards the data-miner. Data from different equipment and different vendors are also merged for efficient data analysis and subsequently charting and reporting. We have also successfully engaged the medical doctors into believing the data miner's capability after they reviewed and walkthrough the prototype.

Using bijective maps to improve free-energy estimates.

We derive a fluctuation theorem for generalized work distributions, related to bijective mappings of the phase spaces of two physical systems, and use it to derive a two-sided constraint maximum likelihood estimator of their free-energy difference which uses samples from the equilibrium configurations of both systems. As an application, we evaluate the chemical potential of a dense Lennard-Jones fluid and study the construction and performance of suitable maps.

Utilization of photon orbital angular momentum in the low-frequency radio domain.

We show numerically that vector antenna arrays can generate radio beams that exhibit spin and orbital angular momentum characteristics similar to those of helical Laguerre-Gauss laser beams in paraxial optics. For low frequencies (< or = 1 GHz), digital techniques can be used to coherently measure the instantaneous, local field vectors and to manipulate them in software. This enables new types of experiments that go beyond what is possible in optics. It allows information-rich radio astronomy and paves the way for novel wireless communication concepts.