High Speed and Low-Noise Open-Path Gas Detection System
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07 ISOTOPE AND RADIATION SOURCES↗
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Multi-species outbreak of SARS-CoV-2 Delta variant in a zoological institution, with the detection in two new families of carnivores
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has a worldwide distribution in humans and many other mammalian species. In late September 2021, 12 animals maintained by the Chicago Zoological Society's Brookfield Zoo were observed with variable clinical signs. The Delta variant of SARS-CoV-2 was detected in faeces and nasal swabs by qRT-PCR, including the first detection in animals from the families Procyonidae and Viverridae. Test positivity rate was 12.5% for 35 animals tested. All animals had been vaccinated with at least one dose of a recombinant vaccine designed for animals and all recovered with variable supportive treatment. Sequence analysis showed that six zoo animal strains were closely correlated with 18 human SARS-CoV-2 strains, suggestive of potential human-to-animal transmission events. This report documents the expanding host range of COVID-19 during the ongoing pandemic.
59 BASIC BIOLOGICAL SCIENCES↗
A deterministic verification strategy for electrostatic particle-in-cell algorithms in arbitrary spatial dimensions using the method of manufactured solutions
As simulations of kinetic plasmas continue to increase in scope and complexity, a rigorous and straightforward method for verifying particle-in-cell (PIC) implementations is necessary to ensure their correctness. Here, in this paper, we present a deterministic method for the rigorous verification of multidimensional, multispecies, electrostatic particle-in-cell codes based on the method of manufactured solutions. Specifically, we prove that rigorous verification is possible through the exclusive examination of errors of grid quantities (i.e., moments and/or fields), allowing for a very light-weight and non-intrusive implementation in existing PIC codes. This is a marked improvement over earlier PIC verification approaches (only demonstrated with one species in 1D-1V), which rely on the comparison of cumulative distribution functions, and are invasive on the code base, introduce additional stochastic noise, are significantly more computationally expensive, and lack rigorous convergence properties. Interestingly, we show that different grid quantities feature different rates of convergence with the number of particles and mesh size, impacting the verification process. These theoretical results are confirmed numerically with a multi-species 2D-2V particle-in-cell code, including the ability of the method to detect order reduction due to an incorrect implementation.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
Differentiating multi-MeV, multi-ion spectra with CR-39 solid-state nuclear track detectors
The development of high intensity petawatt lasers has created new possibilities for ion acceleration and nuclear fusion using solid targets. In such laser-matter interaction, multiple ion species are accelerated with broad spectra up to hundreds of MeV. To measure ion yields and for species identification, CR-39 solid-state nuclear track detectors are frequently used. However, these detectors are limited in their applicability for multi-ion spectra differentiation as standard image recognition algorithms can lead to a misinterpretation of data, there is no unique relation between track diameter and particle energy, and there are overlapping pit diameter relationships for multiple particle species. In this report, we address these issues by first developing an algorithm to overcome user bias during image processing. Second, we use calibration of the detector response for protons, carbon and helium ions (alpha particles) from 0.1 to above 10 MeV and measurements of statistical energy loss fluctuations in a forward-fitting procedure utilizing multiple, differently filtered CR-39, altogether enabling high-sensitivity, multi-species particle spectroscopy. To validate this capability, we show that inferred CR-39 spectra match Thomson parabola ion spectrometer data from the same experiment. Filtered CR-39 spectrometers were used to detect, within a background of ~ 2 × 10 11 sr -1 J -1 protons and carbons, (1.3 ± 0.7) × 10 8 sr -1 J -1 alpha particles from laser-driven proton-boron fusion reactions.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
The impact of simultaneous inoculation of Pseudomonas aeruginosa, Staphylococcus aureus , and Candida albicans on rodent burn wounds
Burn wound infection often involves a diverse combination of bacterial and fungal pathogens. In this study, we characterize the mixed species burn wound infection by inoculating the burn surface with 1 × 10 3/4/5 CFU of Pseudomonas aeruginosa, Staphylococcus aureus, and Candida albicans in a 1:1:1 ratio. Using the revised Walker–Mason scald burn rat model, 168 male Sprague-Dawley rats (350–450 g) subject to ~10% TBSA burn injury, with or without inoculation, were evaluated for 11 days after burn. In the wound, P. aeruginosa and S. aureus formed robust biofilms as determined by the bacterial tissue load, ~1 × 10 9 CFU/g, and expression of key biofilm genes. Interestingly, within 3 days C. albicans achieved tissue loads of ~1 × 10 6 CFU/g, but its numbers were significantly reduced beyond the limit of detection in the burn wound by day 7 in partial-thickness injuries and by day 11 in full-thickness injuries. The pathogenic biofilms contributed to burn depth progression, increased release of HMGB-1 into circulation from injured tissue, and significantly elevated the numbers of circulating innate immune cells (Neutrophils, Monocytes, and Basophils). This robust model of multi-species burn wound infection will serve as the basis for the development of new antimicrobials for combating biofilm-based wound infections.
60 APPLIED LIFE SCIENCES↗
Nonlinear coupling of electromagnetic and electron acoustic waves in multi-species degenerate astrophysical plasma
Nonlinear wave-coupling is studied in a multispecies degenerate astrophysical plasma consisting of two electron species (at different temperatures): a highly degenerate main component plus a smaller classical relativistic flow immersed in a static neutralizing ion background. It is shown that the high frequency electromagnetic waves through their strong nonlinear interactions with the electron-acoustic waves [sustained by a multielectron component (degenerate) plasma surrounding a compact astrophysical object] can scatter to lower frequencies so that the radiation observed faraway will be spectrally shifted downward. It is also shown that, under definite conditions, the electromagnetic waves could settle into stationary solitonic states. It is expected that the effects of such structures may persist as detectable signatures in forms of modulated micropulses in the radiation observed far away from the accreting compact object. Both these effects will advance our abilities to interpret the radiation coming out of the compact objects.
70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗