Numerical simulations of astrophysical cyclotron-maser emission

[Abstract unavailable

Laboratory investigation of cyclotron emission processes for auroral radiation

When a beam of electrons encounters an increasing magnetic field along its vector of motion, conservation of the magnetic moment results in the formation of a crescent or horseshoe shaped velocity distribution. A scenario analogous to this occurs in the terrestrial auroral zone where particles are accelerated into the polar regions of the Earth's magnetic dipole and expand adiabatically in velocity space. The resultant horseshoe shaped velocity distribution has been shown to be unstable with respect to a cyclotron-maser type instability. This instability has been postulated as the mechanism responsible for auroral kilometric radiation and thermal radiation from other astrophysical bodies. In this paper we present the results of recent numerical simulations and laboratory investigations of radiation emissions from electron beam which have been subject to magnetic compression. Electron beam diagnostics demonstrated the formation of the desired velocity distribution. Radiation was generated at both 11.7GHz and 4.45GHz by an electron beam of current 5-25A and energy 75kV subject to magnetic compression ration of up to 30. Conversion efficiencies between beam and radiation power were achieved of up to 2.5% and strong agreement was achieved between the numerical investigations and the experimental measurements

Treatment strategies for tics in Tourette syndrome

Tourette syndrome (TS) is a chronic neurodevelopmental disorder characterized by tics: repetitive, involuntary movements and vocalizations. These symptoms can have a significant impact on patients’ daily functioning across many domains. Tics tend to be most severe in child and adolescent sufferers, so their presence has the potential to impact a period of life that is both critical for learning and is often associated with the experience of greater social tension and self-consciousness than adulthood. Furthermore, control over tics that lead to physical impairment or self-injurious behaviour is of vital importance in maintaining health and quality of life. There are numerous complicating factors in the prescription of treatment for tics, due to both the side effects associated with alleviating agents and patient characteristics, such as age and comorbid conditions. This review summarizes literature pertaining to the efficacy and safety of both traditionally prescribed and more modern medications. We also discuss the merits of behavioural and surgical techniques and highlight newer emerging treatments. Although treatment response is to some extent variable, there are a number of agents that are clearly useful as first-line treatments for TS. Other interventions may be of most benefit to patients exhibiting refractory tics or more specific symptom profiles