Validity of the Taylor Hypothesis for Linear Kinetic Waves in the Weakly Collisional Solar Wind

The interpretation of single-point spacecraft measurements of solar wind turbulence is complicated by the fact that the measurements are made in a frame of reference in relative motion with respect to the turbulent plasma. The Taylor hypothesis---that temporal fluctuations measured by a stationary probe in a rapidly flowing fluid are dominated by the advection of spatial structures in the fluid rest frame---is often assumed to simplify the analysis. But measurements of turbulence in upcoming missions, such as Solar Probe Plus, threaten to violate the Taylor hypothesis, either due to slow flow of the plasma with respect to the spacecraft or to the dispersive nature of the plasma fluctuations at small scales. Assuming that the frequency of the turbulent fluctuations is characterized by the frequency of the linear waves supported by the plasma, we evaluate the validity of the Taylor hypothesis for the linear kinetic wave modes in the weakly collisional solar wind. The analysis predicts that a dissipation range of solar wind turbulence supported by whistler waves is likely to violate the Taylor hypothesis, while one supported by kinetic Alfven waves is not.Comment: 10 pages, 3 figures, Accepted for publication in The Astrophysical Journa

Hydrogen-oxygen electrolytic regenerative fuel cells Quarterly report, 1 Jan. - 31 Mar. 1966

Hydrogen-oxygen regenerative fuel cell testing to improve cycle life capability and to investigate modes of cell performance deterioratio

Structural and mechanical effects of interstitial sinks

Structural changes in niobium base alloys induced by exposure to titanium interstitial sink at elevated temperatur

Jet reconstruction and jet background classification with the ALICE experiment in PbPb collisions at the LHC

For a quantitative interpretation of reconstructed jet properties in heavy-ion collisions it is paramount to characterize the contribution from the underlying event and the influence of background fluctuations on the jet signal. In addition to the pure number fluctuations, region-to-region correlated background within one event can enhance or deplete locally the level of background and modify the jet energy. We show a first detailed assessment of background effects using different probes embedded into heavy-ion data and quantify their influence on the reconstructed jet spectrum.Comment: 4 pages, 2 figures, Proceedings for the XXII International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Quark Matter 2011, Annec

Electrolytically regenerative hydrogen-oxygen fuel cell Patent

Electrolytically regenerative hydrogen-oxygen fuel cell

M82 - A radio continuum and polarisation study II. Polarisation and rotation measures

The composition and morphology of the interstellar medium in starburst galaxies has been well investigated, but the magnetic field properties are still uncertain. The nearby starburst galaxy M82 provides a unique opportunity to investigate the mechanisms leading to the amplification and reduction of turbulent and regular magnetic fields. Possible scenarios of the contribution of the magnetic field to the star-formation rate are evaluated. Archival data from the VLA and WSRT were combined and re-reduced to cover the wavelength regime between 3cm and 22cm. All observations revealed polarised emission in the inner part of the galaxy, while extended polarised emission up to a distance of 2kpc from the disk was only detected at 18cm and 22cm. The observations hint at a magnetised bar in the inner part of the galaxy. We calculate the mass inflow rate due to magnetic stress of the bar to 7.1 solar masses per year, which can be a significant contribution to the star-formation rate of M82 of approximately 13 solar masses per year. The halo shows polarised emission, which might be the remnant of a regular disk field. Indications for a helical field in the inner part of the outflow cone are provided. The coherence length of the magnetic field in the centre is similar to the size of giant molecular clouds. Using polarisation spectra more evidence for a close coupling of the ionised gas and the magnetic field as well as a two-phase magnetic field topology were found. Electron densities in the halo are similar to the ones found in the Milky Way. The magnetic field morphology is similar to the one in other nearby starburst galaxies with possible large-scale magnetic loops in the halo and a helical magnetic field inside the outflow cones. The special combination of a magnetic bar and a circumnuclear ring are able to significantly raise the star-formation rate in this galaxy by magnetic braking