Combining Harmonic Generation and Laser Chirping to Achieve High Spectral Density in Compton Sources

Recently various laser-chirping schemes have been investigated with the goal of reducing or eliminating ponderomotive line broadening in Compton or Thomson scattering occurring at high laser intensities. As a next level of detail in the spectrum calculations, we have calculated the line smoothing and broadening expected due to incident beam energy spread within a one-dimensional plane wave model for the incident laser pulse, both for compensated (chirped) and unchirped cases. The scattered compensated distributions are treatable analytically within three models for the envelope of the incident laser pulses: Gaussian, Lorentzian, or hyperbolic secant. We use the new results to demonstrate that the laser chirping in Compton sources at high laser intensities: (i) enables the use of higher order harmonics, thereby reducing the required electron beam energies; and (ii) increases the photon yield in a small frequency band beyond that possible with the fundamental without chirping. This combination of chirping and higher harmonics can lead to substantial savings in the design, construction and operational costs of the new Compton sources. This is of particular importance to the the widely popular laser-plasma accelerator based Compton sources, as the improvement in their beam quality enters the regime where chirping is most effective.Comment: 5 pages, 4 figure

Urban Air Mobility Fleet Manager Gap Analysis and System Design

NASA's Urban Air Mobility (UAM) Sub-Project is engaged in research to support the introduction of air taxis into the National Airspace System. Such operations will require a range of communication, navigation, and surveillance systems. Air vehicles for UAM are under development and will initially have human pilots. Separation from other aircraft, obstacles, and weather may be a pilot responsibility or provided by an operator's ground-based systems. Eventually, air taxis may be flown from the ground or fly autonomously. There will be a need for dispatch services for UAM. This report presents a gap analysis, data and capability requirements, and workstation design concepts for the UAM dispatcher or Fleet Manager (FM) position

Using Land Values to Predict Future Farm Income

land values, almon lag, farm profitability, Agribusiness, Agricultural Finance, Farm Management, Financial Economics, Production Economics,

Performance statistics of the FORTRAN 4 /H/ library for the IBM system/360

Test procedures and results for accuracy and timing tests of the basic IBM 360/50 FORTRAN 4 /H/ subroutine library are reported. The testing was undertaken to verify performance capability and as a prelude to providing some replacement routines of improved performance

Data Comets: Designing a Visualization Tool for Analyzing Autonomous Aerial Vehicle Logs with Grounded Evaluation

Autonomous unmanned aerial vehicles are complex systems of hardware, software, and human input. Understanding this complexity is key to their development and operation. Information visualizations already exist for exploring flight logs but comprehensive analyses currently require several disparate and custom tools. This design study helps address the pain points faced by autonomous unmanned aerial vehicle developers and operators. We contribute: a spiral development process model for grounded evaluation visualization development focused on progressively broadening target user involvement and refining user goals; a demonstration of the model as part of developing a deployed and adopted visualization system; a data and task abstraction for developers and operators performing post-flight analysis of autonomous unmanned aerial vehicle logs; the design and implementation of DATA COMETS, an open-source and web-based interactive visualization tool for post-flight log analysis incorporating temporal, geospatial, and multivariate data; and the results of a summative evaluation of the visualization system and our abstractions based on in-the-wild usage. A free copy of this paper and source code are available at osf.io/h4p7gComment: EuroVis 2020 Full Pape

A Search for Pulsation in Very Low-mass Stars and Brown Dwarfs

Brown dwarfs and very low-mass stars constitute a crucial link between the intertwined processes of star formation and planet formation. To date, however, observational methods to uncover their formation mechanism or determine important properties such as mass and age have been lacking. Pulsation powered by deuterium burning in brown dwarfs and very low-mass stars is a newly suggested phenomenon that offers unprecedented opportunities to probe the interiors and evolution of these objects. We report on a photometric campaign to search for low-amplitude pulsations among young star-cluster members using a number of telescopes

The scaffold protein POSH regulates T lymphocyte function

T lymphocytes are critical mediators of the adaptive immune response. T cell receptor (TCR) mediated cJUN NH2-terminal kinase (JNK) activation is required for mounting proper T cell mediated immune responses. However, little is know as to how JNK activation is coupled to the TCR. This dissertation shows that the scaffold protein Plenty of SH3s (POSH) is required for optimal JNK activation and effector function in both CD4+ and CD8+ T cells. Additionally, this work shows that POSH is dispensable for JNK activation and positive and negative selection in developing thymocytes. Thus, POSH couples the TCR to JNK activation in a cell type and developmental stage dependent manner. This work also revels a novel target for the treatment of autoimmune disorders such as Type I Diabetes and Multiple Sclerosis