4,328 research outputs found
Two-Pulse Ionization Injection into Quasi-Linear Laser Wakefields
We describe a scheme for controlling electron injection into the quasi-linear
wakefield driven by a guided drive pulse via ionization of a dopant species by
a collinear injection laser pulse with a short Rayleigh range. The scheme is
analyzed by particle in cell simulations which show controlled injection and
acceleration of electrons to an energy of 370 MeV, a relative energy spread of
2%, and a normalized transverse emittance of 3.0 {\mu}m.
This is an arXiv version of the original APS paper. It should be cited as N.
Bourgeois, J. Cowley, and S. M. Hooker, Phys. Rev. Lett. 111, 155004 (2013).
APS link here: http://link.aps.org/doi/10.1103/PhysRevLett.111.155004Comment: 5 pages, 4 figure
Quasi-phasematching of harmonic generation via multimode beating in waveguides
A new scheme for quasi-phasematching high harmonic generation (HHG) in gases
is proposed. In this, the rapid variation of the axial intensity resulting from
excitation of more than one mode of a waveguide is used to achieve quasi
phasematching. Numerical modeling demonstrates enhancement of the harmonic
signal over that achieved for a single coherence length by factors >10^4.Comment: 6 pages including 3 figure
Quasi-phase-matching of high-order-harmonic generation using multimode polarization beating
The generalization of quasi-phase-matching using polarization beating and of
multimode quasi-phase-matching (MMQPM) for the generation of high-order
harmonics is explored, and a method for achieving polarization beating is
proposed. If two (and in principle more) modes of a waveguide are excited,
modulation of the intensity, phase, and/or polarization of the guided radiation
will be achieved. By appropriately matching the period of this modulation to
the coherence length, quasi-phase-matching of high-order-harmonic radiation
generated by the guided wave can occur. We show that it is possible to achieve
efficiencies with multimode quasi-phase-matching greater than the ideal square
wave modulation. We present a Fourier treatment of QPM and use this to show
that phase modulation, rather than amplitude modulation, plays the dominant
role in the case of MMQPM. The experimental parameters and optimal conditions
for this scheme are explored
Complete spatial characterization of an optical wavefront using a variable-separation pinhole pair
We present a technique for measuring the transverse spatial properties of an
optical wavefront. Intensity and phase profiles are recovered by analysis of a
series of interference patterns produced by the combination of a scanning
X-shaped slit and a static horizontal slit; the spatial coherence may be found
from the same data. We demonstrate the technique by characterizing high
harmonic radiation generated in a gas cell, however the method could be
extended to a wide variety of light sources.Comment: 4 pages, 3 figures, 1 tabl
Teaching Population Health: Innovations in the integration of the healthcare and public health systems
Population health is a critical concept in healthcare delivery today. Many healthcare administrators are struggling to adapt their organization from fee-for-service to value delivery. Payers and patients expect healthcare leaders to understand how to deliver care under this new model. Health administration programs play a critical role in training future leaders of healthcare organizations to be adaptable and effective in this dynamic environment. The purpose of this research was to: (a) engage current educators of health administration students in a dialogue about the best practices of integrating the healthcare and public health systems; (b) identify the content and pedagogy for population health in the undergraduate and graduate curricula; and (c) discuss exemplar population health curriculum models, available course materials, and curriculum integration options. Authors conducted focus groups of participants attending this educational session at the 2017 annual AUPHA meeting. Qualitative analysis of the focus group discussions was performed and themes identified by a consensus process. Study findings provide validated recommendations for population health in the health administration curriculum. The identification of key content areas and pedagogical approaches serves to inform health educators as they prepare future health administrators to practice in this new era of population health
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Modular Strategies for PET Imaging Agents
In recent years, modular and simplified chemical and biological strategies have been developed for the synthesis and implementation of positron emission tomography (PET) radiotracers. New developments in bioconjugation and synthetic methodologies, in combination with advances in macromolecular delivery systems and gene-expression imaging, reflect a need to reduce radiosynthesis burden in order to accelerate imaging agent development. These new approaches, which are often mindful of existing infrastructure and available resources, are anticipated to provide a more approachable entry point for researchers interested in using PET to translate in vitro research to in vivo imaging.Chemistry and Chemical Biolog
From Café to stage to museum: The transformation of the Gypsy music industry in 20th century Hungary
With a few exceptions, the scholarly literature on Hungary’s Gypsy music remains frozen in an increasingly remote past, in what Budapest journalist Imre Déri in 1912 called “the old patriarchal relationship between the Gypsies and the gentlemenmerry-makers.” Yet Gypsy musicians thrived in the twentieth century, through dramatic social and economic changes, adapting to new institutional frameworks and audience expectations. In the early days of the Hungarian Radio, culture brokers attempted to regularize sound production to fit the technical demands of this new medium, in the process asserting new controls over the musicians; their proposed changes led to a public conflict with the musicians, the “Gypsy war” of 1934. Under socialism the state initially strove to break the “feudalist-capitalist” framework of the previous system by closing restaurants, but then reopened them as sites for workers’ entertainment and tourist revenue; additionally, Hungary’s professional folk ensembles (created there and throughout the East bloc after the model of Igor Moiseyev’s ensemble in the USSR) filled the ranks of their orchestras with Gypsy musicians almost exclusively until the 1980s. Using oral history interviews and journalistic and archival sources, this essay shows how these artists sought both economic stability and recognition as they negotiated changing conditions
Pedagogy: How to best teach population health to future healthcare leaders
Our healthcare system is moving from a fee-for-service reimbursement model to one that provides payment for improvements in three areas related to care: quality, coordination, and cost. Healthcare organizations must use a population health approach when delivering care under this new paradigm. Health administration programs play a critical role in training future leaders of healthcare organizations to be adaptable and effective in this dynamic environment. The purpose of this research was to: (1) engage health administration educators in a dialogue about population health and its relevance to healthcare administration education; (2) describe pedagogical methods appropriate for teaching population health skills and abilities needed for successful careers in our healthcare environment; and (3) identify current student learning outcomes that participants can tailor to utilize in their undergraduate and graduate health management courses. Authors conducted focus groups of participants attending this educational session at the 2018 annual AUPHA meeting. Qualitative analysis of the focus group discussions identified themes by a consensus process. Study findings provide validated recommendations for population health in the health administration curriculum. The identification of pedagogical approaches serves to inform educators as they prepare future health administrators to practice in this new era of healthcare delivery
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