Dust acoustic wave in a strongly magnetized pair-dust plasma

The existence of the dust acoustic wave (DAW) in a strongly magnetized electron-positron (pair)-dust plasma is demonstrated. In the DAW, the restoring force comes from the pressure of inertialess electrons and positrons, and the dust mass provides the inertia. The waves could be of interest in astrophysical settings such as the supernovae and pulsars, as well as in cluster explosions by intense laser beams in laboratory plasmas.Comment: 6 pages, revtex

Gas exploration and production at the Dutch continental shelf: an assessment of the 'Depreciation at Will'.

This report analyses the effects of Depreciation at Will (DAW) on offshore gas production, government budget and employment in the gas industry. The DAW enables firms to accelerate deprecation of investments in platforms and other offshore equipment. The interest advantage due to the postponed payments of taxes raises the profitability of investment projects and, hence, could raise the level of investments. The key question in the debate on the DAW is whether the higher tax base compensates for the interest losses due to postponed tax receipts. The econometric analysis has shown that the DAW increased only the number of development drillings during the period this measure was implemented (1996-2002). A moving long-run average of the oil price has appeared to be a significantly explaining variable behind the level of exploration drillings as well as development drillings. Using the current value of that oil price, 25 dollar per barrel, we find a large number of profitable exploration projects. In the current circumstances, introduction of the DAW will not raise the level of investments in the near future, as several non-financial factors appear to be bottlenecks, such as the duration of licensing procedures. The econometric analysis is also published in A. ten Cate en M. Mulder, 2007, "Impact of the oil price and fiscal facilities on offshore mining at the Dutch Continental Shelf", Energy Policy , vol 35, pp 5601-5613.

Particle acceleration by circularly and elliptically polarised dispersive Alfven waves in a transversely inhomogeneous plasma in the inertial and kinetic regimes

Dispersive Alfven waves (DAWs) offer, an alternative to magnetic reconnection, opportunity to accelerate solar flare particles. We study the effect of DAW polarisation, L-, R-, circular and elliptical, in different regimes inertial and kinetic on the efficiency of particle acceleration. We use 2.5D PIC simulations to study how particles are accelerated when DAW, triggered by a solar flare, propagates in transversely inhomogeneous plasma that mimics solar coronal loop. (i) In inertial regime, fraction of accelerated electrons (along the magnetic field), in density gradient regions is ~20% by the time when DAW develops 3 wavelengths and is increasing to ~30% by the time DAW develops 13 wavelengths. In all considered cases ions are heated in transverse to the magnetic field direction and fraction of the heated particles is ~35%. (ii) The case of R-circular, L- and R- elliptical polarisation DAWs, with the electric field in the non-ignorable transverse direction exceeding several times that of in the ignorable direction, produce more pronounced parallel electron beams and transverse ion beams in the ignorable direction. In the inertial regime such polarisations yield the fraction of accelerated electrons ~20%. In the kinetic regime this increases to ~35%. (iii) The parallel electric field that is generated in the density inhomogeneity regions is independent of m_i/m_e and exceeds the Dreicer value by 8 orders of magnitude. (iv) Electron beam velocity has the phase velocity of the DAW. Thus electron acceleration is via Landau damping of DAWs. For the Alfven speeds of 0.3c the considered mechanism can accelerate electrons to energies circa 20 keV. (v) The increase of mass ratio from m_i/m_e=16 to 73.44 increases the fraction of accelerated electrons from 20% to 30-35% (depending on DAW polarisation). For the mass ratio m_i/m_e=1836 the fraction of accelerated electrons would be >35%.Comment: Final accepted version. To appear in Physics of Plasmas, volume 18, issue 9 (September 2011

Composing/Arranging Familiar Songs in Choir with GarageBand

This practical multi-stage project description demonstrates to teachers how they can engage students in arranging and composing music related to the choral curriculum by using Digital Audio Workstations (DAW) like GarageBand