7,339 research outputs found
Energetic, relativistic and ultra-relativistic electrons: Comparison of long-term VERB code simulations with Van Allen Probes measurements
In this study, we compare long-term simulations performed by the Versatile Electron Radiation Belt (VERB) code with observations from the Magnetic Electron Ion Spectrometer and Relativistic Electron-Proton Telescope instruments on the Van Allen Probes satellites. The model takes into account radial, energy, pitch angle and mixed diffusion, losses into the atmosphere, and magnetopause shadowing. We consider the energetic (\u3e100ākeV), relativistic (~0.5ā1āMeV), and ultrarelativistic (\u3e2āMeV) electrons. One year of relativistic electron measurements (Ī¼ā=ā700āMeV/G) from 1 October 2012 to 1 October 2013 are well reproduced by the simulation during varying levels of geomagnetic activity. However, for ultrarelativistic energies (Ī¼ā=ā3500āMeV/G), the VERB code simulation overestimates electron fluxes and phase space density. These results indicate that an additional loss mechanism is operational and efficient for these high energies. The most likely mechanism for explaining the observed loss at ultrarelativistic energies is scattering by the electromagnetic ion cyclotron waves
Quantifying the fast outflow in the luminous Seyfert galaxy PG1211+143
We report two new XMM-Newton observations of PG1211+143 in December 2007,
again finding evidence of the fast outflow of highly ionised gas first detected
in 2001. Stacking the new spectra with those from two earlier XMM-Newton
observations reveals strong and broad emission lines of FeXXV and OVIII,
indicating the fast outflow to be persistent and to have a large covering
factor. This finding confirms a high mass rate for the ionised ouflow in
PG1211+143 and provides the first direct measurement of a wide angle,
sub-relativistic outflow from an AGN transporting mechanical energy with the
potential to disrupt the growth of the host galaxy. We suggest PG1211+143 may
be typical of an AGN in a rapid super-Eddington growth phase.Comment: Accepted for publication in MNRAS. Extended version with new figures
and table
Pulsed homodyne measurements of femtosecond squeezed pulses generated by single-pass parametric deamplification
A new scheme is described for pulsed squeezed light generation using
femtosecond pulses parametrically deamplified through a single pass in a thin
(0.1mm) potassium niobate KNbO3 crystal, with a significant deamplification of
about -3dB. The quantum noise of each individual pulse is registered in the
time domain using a single-shot homodyne detection operated with femtosecond
pulses and the best squeezed quadrature variance was measured to be 1.87 dB
below the shot noise level. Such a scheme provides the basic ressource for
time-resolved quantum communication protocols.Comment: Accepted for publication in Optics Letter
Developing a cultural competence assessment tool for people in recovery from racial, ethnic and cultural backgrounds: the journey, challenges and lessons learned.
In 1997, Maryland implemented a new managed care mental health system. Consumer satisfaction, evaluation and cultural competency were considered high priorities for the new system. While standardized tools for measuring consumer satisfaction were readily available, no validated, reliable and standardized tool existed to measure the perception of people from minority groups receiving mental health services. The MHA*/MHP* Cultural Competency Advisory Group (CCAG) accepted the challenge of developing a consumer assessment tool for cultural competency. The CCAG, composed of people in recovery, clinicians and administrators used their collective knowledge and experiences to develop a 52-item tool that met standards for validity and reliability. Consultation from a researcher helped to further develop the tool into one possessing tremendous potential for statewide implementation within Maryland's Public Mental Health System. Recognizing the limitations of the study and the need for further research, this instrument is a work in progress. Strategies to improve the instrument are currently underway with the Mental Hygiene Administration's Systems Evaluation Center of the University of Maryland and several national researchers
Unraveling the causes of radiation belt enhancements
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94606/1/eost16149.pd
Enantioselective Construction of Ī±-Quaternary Cyclobutanones by Catalytic Asymmetric Allylic Alkylation
No strain, no gain! The first transition metal-catalyzed enantioselective Ī±-alkylation of cyclobutanones is reported. This method employs palladium catalysis and an electron-deficient PHOX-type ligand to afford all-carbon Ī±-quaternary cyclobutanones in good to excellent yields and enantioselectivities (see scheme)
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