Demonstration of metaplectic geometrical optics for reduced modeling of plasma waves.

The Wentzel, Kramers, and Brillouin (WKB) approximation of geometrical optics is widely used in plasma physics, quantum mechanics, and reduced wave modeling, in general. However, it is well-known that the approximation breaks down at focal and turning points. In this paper, we present an unsupervised numerical implementation of the recently developed metaplectic geometrical optics framework, which extends the applicability of geometrical optics beyond the limitations of WKB, such that the wave field remains finite at caustics.

A radiometer to diagnose parametric instabilities during linear excitation of electron Bernstein waves in the Mega Amp Spherical Tokamak (MAST) Upgrade.

Highly overdense magnetically confined fusion plasmas, such as the Mega Amp Spherical Tokamak (MAST) Upgrade, cannot easily be heated using conventional electron cyclotron resonance heating because high density cutoffs block microwave access to the plasma core. Instead, electromagnetic waves can be coupled to electron Bernstein waves (EBWs) through the O-X-B mode coupling scheme, and the EBWs can then be absorbed at higher densities. The excitation of EBWs occurs at the upper hybrid (UH) layer where nonlinear wave interactions, called parametric decay instabilities (PDIs), are known to occur at reduced power thresholds.

[Not all exacerbations of chronic obstructive pulmonary disease should be treated with antibiotics].

This review gives an update on antibiotic treatment of exacerbation of chronic obstructive pulmonary disease (COPD). Patients who do not need hospital admission and do not present with purulent sputum nor increased levels of C reactive protein/procalcitonin have no beneficial effect of antibiotic treatment. Those with severe COPD and increased sputum purulence should be treated with antibiotics, and first-line treatment should be amoxicillin, which is effective against the most common types of bacteria in COPD exacerbation.