Van Allen belt plasma physics

Plasma turbulence in Van Allen bel

On the detection of magnetospheric radio bursts from Uranus and Neptune

Earth, Jupiter, and Saturn are sources of intense but sporadic bursts of electromagnetic radiation or magnetospheric radio bursts (MRB). The similarity of the differential power flux spectra of the MRB from all three planets is examined. The intensity of the MRB is scaled for the solar wind power input into a planetary magnetosphere. The possibility of detecting MRB from Uranus and Neptune is considered

A limit on stably trapped particle fluxes

Limits of stably trapped particle fluxes - behavior of Whistler and ion cyclotron noise mode

Investigation of magnetospheric physics Technical status report, period ending 31 Mar. 1967

Magnetospheric physics - auroral zone structur

Spatial Evidence for Transition Radiation in a Solar Radio Burst

Microturbulence, i.e. enhanced fluctuations of plasma density, electric and magnetic fields, is of great interest in astrophysical plasmas, but occurs on spatial scales far too small to resolve by remote sensing, e.g., at ~ 1-100 cm in the solar corona. This paper reports spatially resolved observations that offer strong support for the presence in solar flares of a suspected radio emission mechanism, resonant transition radiation, which is tightly coupled to the level of microturbulence and provides direct diagnostics of the existence and level of fluctuations on decimeter spatial scales. Although the level of the microturbulence derived from the radio data is not particularly high, /n^2 ~ 10^{-5}$, it is large enough to affect the charged particle diffusion and give rise to effective stochastic acceleration. This finding has exceptionally broad astrophysical implications since modern sophisticated numerical models predict generation of much stronger turbulence in relativistic objects, e.g., in gamma-ray burst sources.Comment: 13 pages, 4 figures, ApJL accepte

Shearing Box Simulations of the MRI in a Collisionless Plasma

We describe local shearing box simulations of turbulence driven by the magnetorotational instability (MRI) in a collisionless plasma. Collisionless effects may be important in radiatively inefficient accretion flows, such as near the black hole in the Galactic Center. The MHD version of ZEUS is modified to evolve an anisotropic pressure tensor. A fluid closure approximation is used to calculate heat conduction along magnetic field lines. The anisotropic pressure tensor provides a qualitatively new mechanism for transporting angular momentum in accretion flows (in addition to the Maxwell and Reynolds stresses). We estimate limits on the pressure anisotropy due to pitch angle scattering by kinetic instabilities. Such instabilities provide an effective ``collision'' rate in a collisionless plasma and lead to more MHD-like dynamics. We find that the MRI leads to efficient growth of the magnetic field in a collisionless plasma, with saturation amplitudes comparable to those in MHD. In the saturated state, the anisotropic stress is comparable to the Maxwell stress, implying that the rate of angular momentum transport may be moderately enhanced in a collisionless plasma.Comment: 20 pages, 9 figures, submitted to Ap

Estimating good discrete partitions from observed data: symbolic false nearest neighbors

A symbolic analysis of observed time series data requires making a discrete partition of a continuous state space containing observations of the dynamics. A particular kind of partition, called ``generating'', preserves all dynamical information of a deterministic map in the symbolic representation, but such partitions are not obvious beyond one dimension, and existing methods to find them require significant knowledge of the dynamical evolution operator or the spectrum of unstable periodic orbits. We introduce a statistic and algorithm to refine empirical partitions for symbolic state reconstruction. This method optimizes an essential property of a generating partition: avoiding topological degeneracies. It requires only the observed time series and is sensible even in the presence of noise when no truly generating partition is possible. Because of its resemblance to a geometrical statistic frequently used for reconstructing valid time-delay embeddings, we call the algorithm ``symbolic false nearest neighbors''

Are We Really Listening? A Program to Assess and Mitigate Systemic Factors Contributing to Clinician Burnout

Background: Many US physicians are experiencing burnout affecting patient care quality, safety, and experience. Institutions often focus on personal resilience instead of system-level issues. Our leaders developed a novel process to identify and prioritize key system-related stressors and work to mitigate factors that negatively impact clinician wellbeing through a structured Listening Campaign. Methods: The Listening Campaign consists of meeting with each clinician group leader, a group Listening Session, a follow up meeting with the leader, a final report, and a follow-up session. During the Listening Session, clinicians engage in open discussion about what is going well, complete individual reflection worksheets and identify one “wish” to improve their professional satisfaction. Participants rate these wishes to assist with prioritization. Results: As of January 2020, over 200 clinicians participated in 20 listening sessions. One-hundred twenty-two participants completed a survey; 80% stated they benefited from participation and 83% would recommend it to others. Conclusion: Collecting feedback from clinicians on their experience provides guidance for leaders in prioritizing initiatives and opportunities to connect clinicians to organizational resources. A Listening Campaign is a tool recommended for healthcare systems to elicit clinician perspectives and communicate efforts to address systemic factors

Separation of Metal Ions from Liquid Waste Streams

A unique mechanism was verified for removing uranium from continuously flowing aqueous solutions on a carbon nanofiber electrode with a bias voltage of -0.9 volts (dc versus Ag/AgC1). Uranium concentration was reduced from 100 ppm in the inlet feed to below 1 ppm in a single pass. Cell sizes of 1 cm, 2 inch and 4 inch evaluated during this program were all found to electrosorb uranium from an aqueous stream. The 4 inch cell performed well at uranium concentrations of 1000 ppm. Normally, ordinary electrolysis is not an option for removing uranyl ions because the electrodeposition potential is higher than the dissociation voltage of water. Thus, the ability to electrosorb uranium with greater than 99% effectiveness is a surprising result. In addition, the process was found to be reversible, so that the uranium can be released in a highly concentrated form. In addition to verifying the effectiveness of the system on bench top scale, a regeneration protocol was developed, consisting of passing a 0.1 M KNO{sub3}, solution at a pH of 2.0 and an applied potential of +1.0 V (dc versus Ag/AgC1) which resulted in a measured regeneration of 70% of the electrosorbed uranium. Other experiments studied the effect of pH on electrosorption and desorption, establishing a range of pH for both processes. Finally, it was found that, for an inlet solution of 100 ppm, the carbon nanofiber electrodes were able to electrosorb an amount of uranium in excess of 60% of the electrode mass