31,160 research outputs found
Cooperation on Competition: The Multistate Tax Commission and State Corporate Tax Uniformity
This report explores how interstate uniformity of state corporate income taxes has varied over time, the role played by the MTC, and how likely it is that uniformity will be achieved. FRC Report 11
Polarization Structures in the Thomson-Scattered Emission Lines in Active Galactic Nuclei
A line photon incident in an electron-scattering medium is transferred in a
diffusive way both in real space and in frequency space, and the mean number of
scatterings changes as the wavelength shifts from the line center. This leads
to the profile broadening and polarization dependence on the wavelength shift
as a function of the Thomson optical depth . We find that the
polarization of the Thomson-scattered emission lines has a dip around the line
center when does not exceed a few. Various structures such as the
polarization flip are also seen. An application to an ionized halo component
surrounding the broad emission line region in active galactic nuclei is
considered and it is found that the polarization structures may still persist.
Brief discussions on observational implications are given.Comment: 14 pages, 3 figures, accepted for publication in ApJ Letter
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Ionising radiation exposure from medical imaging – A review of Patient's (un) awareness
Introduction: Medical imaging is the main source of artificial radiation exposure. Evidence, however, suggests that patients are poorly informed about radiation exposure when attending diagnostic scans. This review provides an overview of published literature with a focus on nuclear medicine patients on the level of awareness of radiation exposure from diagnostic imaging. Methods: A review of available literature on awareness, knowledge and perception of ionising radiation in medical imaging was conducted. Articles that met the inclusion criteria were subjected to critical appraisal using the Mixed Methods Appraisal Tool. Results: 140 articles identified and screened for eligibility, 24 critically assessed and 4 studies included in synthesis. All studies demonstrated that patients were generally lacking awareness about radiation exposure and highlighted a lack of communication between healthcare professionals and patients with respect to radiation exposure. Conclusion: Studies demonstrate a need to better inform patients about their radiation exposure, and further studies focusing on nuclear medicine patients are particularly warranted. Implications for practice: Adequate and accurate information is crucial to ensure the principle of informed consent is present
Hsp104 Gives Clients the Individual Attention They Need
Yeast heat shock protein 104 (Hsp104), the only known eukaryotic disaggregase, remodels both disordered protein aggregates and cross-β sheet amyloids. To handle this diverse clientele, DeSantis et al. report that Hsp104 hexamers use distinct mechanisms—individual subunits are able to dissolve disordered aggregates, but global subunit cooperativity is required to untangle amyloids
Macroscopic description of particle systems with non-local density-dependent diffusivity
In this paper we study macroscopic density equations in which the diffusion
coefficient depends on a weighted spatial average of the density itself. We
show that large differences (not present in the local density-dependence case)
appear between the density equations that are derived from different
representations of the Langevin equation describing a system of interacting
Brownian particles. Linear stability analysis demonstrates that under some
circumstances the density equation interpreted like Ito has pattern solutions,
which never appear for the Hanggi-Klimontovich interpretation, which is the
other one typically appearing in the context of nonlinear diffusion processes.
We also introduce a discrete-time microscopic model of particles that confirms
the results obtained at the macroscopic density level.Comment: 4 pages, 3 figure
Interplanetary propulsion using inertial fusion
Inertial fusion can be used to power spacecraft within the solar system and beyond. Such spacecraft have the potential for short-duration manned-mission performance exceeding other technologies. We are conducting a study to assess the systems aspects of inertial fusion as applied to such missions, based on the conceptual engine design of Hyde (1983) we describe the required systems for an entirely new spacecraft design called VISTA that is based on the use of DT fuel. We give preliminary design details for the power conversion and power conditioning systems for manned missions to Mars of total duration of about 100 days. Specific mission performance results will be published elsewhere, after the study has been completed
Perceptual adaptation by normally hearing listeners to a simulated "hole" in hearing
Simulations of cochlear implants have demonstrated that the deleterious effects of a frequency misalignment between analysis bands and characteristic frequencies at basally shifted simulated electrode locations are significantly reduced with training. However, a distortion of frequency-to-place mapping may also arise due to a region of dysfunctional neurons that creates a "hole" in the tonotopic representation. This study simulated a 10 mm hole in the mid-frequency region. Noise-band processors were created with six output bands (three apical and three basal to the hole). The spectral information that would have been represented in the hole was either dropped or reassigned to bands on either side. Such reassignment preserves information but warps the place code, which may in itself impair performance. Normally hearing subjects received three hours of training in two reassignment conditions. Speech recognition improved considerably with training. Scores were much lower in a baseline (untrained) condition where information from the hole region was dropped. A second group of subjects trained in this dropped condition did show some improvement; however, scores after training were significantly lower than in the reassignment conditions. These results are consistent with the view that speech processors should present the most informative frequency range irrespective of frequency misalignment. 0 2006 Acoustical Society of America
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