Magnetospheric and solar wind dependences of coupled fast-mode resonances outside the plasmasphere

We investigate the magnetospheric and solar wind factors that control the occurrence probabilities, locations, and frequencies of standing Alfvén waves excited via coupled fast-mode resonances (cFMRs) in the outer magnetosphere's dawn and dusk sectors. The variation of these cFMR properties with the observed magnetospheric plasma density profiles and inputs to the semiempirically modeled magnetic field from the numerical cFMR calculations of Archer et al. (2015) are studied. The probability of cFMR occurrence increases with distance between the magnetopause and the Alfvén speed's local maximum. The latter's location depends on magnetospheric activity: during high activity it is situated slightly outside the plasmapause, whereas at low activity it is found at much larger radial distances. The frequencies of cFMR are proportional to the Alfvén speed near the magnetopause, which is affected by both density and magnetic field variations. The location of the excited resonance, however, depends on the relative steepness of the Alfvén speed radial profile. The steeper this is, the closer the resonance is to the outer boundary and vice versa. The variation of the density profiles with solar wind conditions and activity is also shown

Frequency variability of standing Alfven waves excited by fast mode resonances in the outer magnetosphere

NASA. Grant Number: NAS5-0209

Direct observations of a surface eigenmode of the dayside magnetopause

The abrupt boundary between a magnetosphere and the surrounding plasma, the magnetopause, has long been known to support surface waves. It was proposed that impulses acting on the boundary might lead to a trapping of these waves on the dayside by the ionosphere, resulting in a standing wave or eigenmode of the magnetopause surface. No direct observational evidence of this has been found to date and searches for indirect evidence have proved inconclusive, leading to speculation that this mechanism might not occur. By using fortuitous multipoint spacecraft observations during a rare isolated fast plasma jet impinging on the boundary, here we show that the resulting magnetopause motion and magnetospheric ultra-low frequency waves at well-defined frequencies are in agreement with and can only be explained by the magnetopause surface eigenmode. We therefore show through direct observations that this mechanism, which should impact upon the magnetospheric system globally, does in fact occur

Direct observations of a surface eigenmode of the dayside magnetopause

The abrupt boundary between a magnetosphere and the surrounding plasma, the magnetopause, has long been known to support surface waves. It was proposed that impulses acting on the boundary might lead to a trapping of these waves on the dayside by the ionosphere, resulting in a standing wave or eigenmode of the magnetopause surface. No direct observational evidence of this has been found to date and searches for indirect evidence have proved inconclusive, leading to speculation that this mechanism might not occur. By using fortuitous multipoint spacecraft observations during a rare isolated fast plasma jet impinging on the boundary, here we show that the resulting magnetopause motion and magnetospheric ultra-low frequency waves at well-defined frequencies are in agreement with and can only be explained by the magnetopause surface eigenmode. We therefore show through direct observations that this mechanism, which should impact upon the magnetospheric system globally, does in fact occur

Magnetospheric “magic” frequencies as magnetopause surface eigenmodes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/100327/1/grl50979.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/100327/2/text01.pd

High Antiproliferative Activity of Hydroxythiopyridones over Hydroxypyridones and Their Organoruthenium Complexes

Hydroxypyr(id)ones are a pharmaceutically important class of compounds that have shown potential in diverse areas of drug discovery. We investigated the 3-hydroxy-4-pyridones 1a–1c and 3-hydroxy-4-thiopyridones 1d–1f as well as their Ru(η6-p-cymene)Cl complexes 2a–2f, and report here the molecular structures of 1b and 1d as determined by X-ray diffraction analysis. Detailed cell biological investigations revealed potent cytotoxic activity, in particular of the 3-hydroxy-4-thiopyridones 1d–1f, while the Ru complexes of both compound types were less potent, despite still showing antiproliferative activity in the low μM range. The compounds did not modulate the cell cycle distribution of cancer cells but were cytostatic in A549 and cytotoxic in NCI-H522 non-small lung cancer cells, among other effects on cancer cells