Using Kernel-Based Statistical Distance to Study the Dynamics of Charged Particle Beams in Particle-Based Simulation Codes

Measures of discrepancy between probability distributions (statistical distance) are widely used in the fields of artificial intelligence and machine learning. We describe how certain measures of statistical distance can be implemented as numerical diagnostics for simulations involving charged-particle beams. Related measures of statistical dependence are also described. The resulting diagnostics provide sensitive measures of dynamical processes important for beams in nonlinear or high-intensity systems, which are otherwise difficult to characterize. The focus is on kernel-based methods such as Maximum Mean Discrepancy, which have a well-developed mathematical foundation and reasonable computational complexity. Several benchmark problems and examples involving intense beams are discussed. While the focus is on charged-particle beams, these methods may also be applied to other many-body systems such as plasmas or gravitational systems

Extracting Dynamical Frequencies from Invariants of Motion in Finite-Dimensional Nonlinear Integrable Systems

Integrable dynamical systems play an important role in many areas of science, including accelerator and plasma physics. An integrable dynamical system with $n$ degrees of freedom (DOF) possesses $n$ nontrivial integrals of motion, and can be solved, in principle, by covering the phase space with one or more charts in which the dynamics can be described using action-angle coordinates. To obtain the frequencies of motion, both the transformation to action-angle coordinates and its inverse must be known in explicit form. However, no general algorithm exists for constructing this transformation explicitly from a set of $n$ known (and generally coupled) integrals of motion. In this paper we describe how one can determine the dynamical frequencies of the motion as functions of these $n$ integrals in the absence of explicitly-known action-angle variables, and we provide several examples.Comment: Accepted, to appear in Phys. Rev.

Net Farm Income Impacts of Alternative Risk Management Bills

The impacts of the bills are measured against the FAPRI January 1999 baseline which may be found at http://hdl.handle.net/10355/3318At the request of Senator Richard Lugar, Chairman of the Committee on Agriculture, Nutrition and Forestry, FAPRI has analyzed impacts of two alternative risk management proposals. The first proposal is the Farmers' Risk Management Act of 1999, sponsored by Senator Lugar (IN) and co-sponsored by Senators McConnell (KY), Fitzgerald (IL), and Helms (NC). The second proposal is the Risk Management for the 21st Century Act, put forth by Senator Roberts (KS) and co-sponsored by Senator Kerrey (NE) and others

Analysis of Risk Management Proposals

An earlier analysis which concentrated on the aggregate net farm income and government outlay impacts may be found at http://hdl.handle.net/10355/3318At the request of several members of the Committee on Agriculture, Nutrition, and Forestry of the Senate, FAPRI has continued to analyze the impacts of two alternative risk management proposals. The proposals are the Farmers' Risk Management Act of 1999 (S. 1666) and the Risk Management for the 21st Century Act (S. 1580)

Accurate Transfer Maps for Realistic Beamline Elements: Part I, Straight Elements

The behavior of orbits in charged-particle beam transport systems, including both linear and circular accelerators as well as final focus sections and spectrometers, can depend sensitively on nonlinear fringe-field and high-order-multipole effects in the various beam-line elements. The inclusion of these effects requires a detailed and realistic model of the interior and fringe fields, including their high spatial derivatives. A collection of surface fitting methods has been developed for extracting this information accurately from 3-dimensional field data on a grid, as provided by various 3-dimensional finite-element field codes. Based on these realistic field models, Lie or other methods may be used to compute accurate design orbits and accurate transfer maps about these orbits. Part I of this work presents a treatment of straight-axis magnetic elements, while Part II will treat bending dipoles with large sagitta. An exactly-soluble but numerically challenging model field is used to provide a rigorous collection of performance benchmarks.Comment: Accepted to PRST-AB. Changes: minor figure modifications, reference added, typos corrected

Community College Presidents and Campus Safety: Perspectives on Critical Issues

Community college presidents must understand the phenomenon of campus safety. For this mixed-methods study, community college presidents in one state were surveyed, and three presidents from the same community college system participated in in-depth interviews. Descriptive statistics measured the levels community college presidents’ knowledge and perceptions on campus safety. The in-depth interviews provided a deeper understanding of the connections between community college presidents and campus safety. Overall, the results show that campus safety is important to community college presidents, who believe that, overall, their institutions are safe. We found that community college presidents believe they should be proactive and reinforce values that promote and prioritize campus safety, follow regulations, and provide sufficient resources to ensure campus safety measures. However, inadequate funding also plays a role in what can be allocated, and community college presidents voiced that they were concerned about promoting safety in the face of declining budgets and resources

Prospectus, September 4, 1985

https://spark.parkland.edu/prospectus_1985/1016/thumbnail.jp

Interrogating a Hexokinase-Selected Small-Molecule Library for Inhibitors of Plasmodium falciparum Hexokinase

This is the published version.Parasites in the genus Plasmodium cause disease throughout the tropic and subtropical regions of the world. P. falciparum, one of the deadliest species of the parasite, relies on glycolysis for the generation of ATP while it inhabits the mammalian red blood cell. The first step in glycolysis is catalyzed by hexokinase (HK). While the 55.3-kDa P. falciparum HK (PfHK) shares several biochemical characteristics with mammalian HKs, including being inhibited by its products, it has limited amino acid identity (∼26%) to the human HKs, suggesting that enzyme-specific therapeutics could be generated. To that end, interrogation of a selected small-molecule library of HK inhibitors has identified a class of PfHK inhibitors, isobenzothiazolinones, some of which have 50% inhibitory concentrations (IC50s) of <1 μM. Inhibition was reversible by dilution but not by treatment with a reducing agent, suggesting that the basis for enzyme inactivation was not covalent association with the inhibitor. Lastly, six of these compounds and the related molecule ebselen inhibited P. falciparum growth in vitro (50% effective concentration [EC50] of ≥0.6 and <6.8 μM). These findings suggest that the chemotypes identified here could represent leads for future development of therapeutics against P. falciparum

Prospectus, August 26, 1985

https://spark.parkland.edu/prospectus_1985/1015/thumbnail.jp

A Laser-Plasma Ion Beam Booster Based on Hollow-Channel Magnetic Vortex Acceleration

Laser-driven ion acceleration can provide ultra-short, high-charge, low-emittance beams. Although undergoing extensive research, demonstrated maximum energies for laser-ion sources are non-relativistic, complicating injection into high-$\beta$ accelerator elements and stopping short of desirable energies for pivotal applications, such as proton tumor therapy. In this work, we decouple the efforts towards relativistic beam energies from a single laser-plasma source via a proof-of-principle concept, boosting the beam into this regime through only a few plasma stages. We employ full 3D particle-in-cell simulations to demonstrate the capability for capture of high-charge beams as produced by laser-driven sources, where both source and booster stages utilize readily available laser pulse parameters.Comment: 4 pages, 4 figures, submitted for peer revie