Thermal Inactivation of Bacillus anthracis Using Laser Irradiation of Micro-Etched Platforms

The purpose of this research was to determine the probability of kill for a thermal inactivation strategy for use against biological agents; specifically the resilient endospore of Bacillus anthracis (Ba). The effort focused on short durations (milliseconds to several seconds) and temperatures (300 to 1300 K) simulating the periphery effects after an explosion generated by conventional munitions. For an improved statistical counting, applied microlithography techniques were used to produce micro-etched glass platforms consisting of 532 circular sample wells, evenly spaced. Small carbon black radiators, which provide fast heating/cooling rate and confined temperature distribution, were produced by populating the etched wells with fine carbon particles for good contact with the spores. In order to prevent the carbon black from oxidation at high temperatures in air, a multifunctional sol-gel coating was designed to cover both the hydrophilic glass surface and hydrophobic carbon surface. Ba spores were sparely populated into the small wells on another micro-etched platform for improved statistical counting. The platform with carbon wells was paired with the other platform populated with the spores by aligning row by row and column by column using a laser diffraction method aided with an infrared beam finder. The study refined techniques to populate the sample wells with as few as one Ba spore per well. This enables researchers to qualify, quantify, treat and measure small samples of spores over time. Spores were heated against black carbon wells using a solid state laser (Nd:YAG). Heating temperatures were varied by using different laser powers. The heating times were controlled by adjusting the raster rate of the sample relative to the laser beam

Proceedings of the opening of the Drug Addiction Research Unit of the University of Hong Kong

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A numerical study of the effects of wind forcing on the Chilean Current System

Distinguished Alumni Award Program author. CAPT Jeffrey Bacon, USN (Ret) (Presented 14 Oct 06)A high-resolution, multi-level, primitive equation ocean model is used to examine the response of an idealized, flat-bottomed, eastern boundary oceanic regime on a beta-plane to both steady and daily-varying climatological wind forcing. The area of study is a coastal region within the Chile Current System from 22°Sto34°S. When steady wind forcing is used, an equatorward surface current and poleward flowing undercurrent develop. Eddies are also generated, with initial formation in the poleward end of the domain. When daily-varying wind forcing is used, there is large spatial variability in the oceanic response. A relatively weak poleward flowing undercurrent appears, first in the poleward part of the domain. An equatorward surface current also develops and intensifies during the upwelling season. Eddies are generated and develop farther poleward in the domain than in the first experiment. The eddies are largest in the equatorward end of the domain. The eddy motion is closely tied to seasonal influences, with cyclonic (divergent) eddies traversing towards areas of higher dynamic heights when there are divergent wind fields present, and vice versa. In addition to the currents and eddies, upwelling and cold filaments are evident in both experiments.http://www.archive.org/details/numericalstudyof00bac

Measuring galaxy [OII] emission line doublet with future ground-based wide-field spectroscopic surveys

The next generation of wide-field spectroscopic redshift surveys will map the large-scale galaxy distribution in the redshift range 0.7< z<2 to measure baryonic acoustic oscillations (BAO). The primary optical signature used in this redshift range comes from the [OII] emission line doublet, which provides a unique redshift identification that can minimize confusion with other single emission lines. To derive the required spectrograph resolution for these redshift surveys, we simulate observations of the [OII] (3727,3729) doublet for various instrument resolutions, and line velocities. We foresee two strategies about the choice of the resolution for future spectrographs for BAO surveys. For bright [OII] emitter surveys ([OII] flux ~30.10^{-17} erg /cm2/s like SDSS-IV/eBOSS), a resolution of R~3300 allows the separation of 90 percent of the doublets. The impact of the sky lines on the completeness in redshift is less than 6 percent. For faint [OII] emitter surveys ([OII] flux ~10.10^{-17} erg /cm2/s like DESi), the detection improves continuously with resolution, so we recommend the highest possible resolution, the limit being given by the number of pixels (4k by 4k) on the detector and the number of spectroscopic channels (2 or 3).Comment: 5 pages, 1 figur

A new method for imaging nuclear threats using cosmic ray muons

Muon tomography is a technique that uses cosmic ray muons to generate three dimensional images of volumes using information contained in the Coulomb scattering of the muons. Advantages of this technique are the ability of cosmic rays to penetrate significant overburden and the absence of any additional dose delivered to subjects under study above the natural cosmic ray flux. Disadvantages include the relatively long exposure times and poor position resolution and complex algorithms needed for reconstruction. Here we demonstrate a new method for obtaining improved position resolution and statistical precision for objects with spherical symmetry

Obtaining material identification with cosmic ray radiography

The passage of muons through matter is mostly affected by their Coulomb interactions with electrons and nuclei. The muon interactions with electrons lead to continuous energy loss and stopping of muons, while their scattering off nuclei lead to angular 'diffusion'. By measuring both the number of stopped muons and angular changes in muon trajectories we can estimate density and identify materials. Here we demonstrate the material identification using data taken at Los Alamos with the Mini Muon Tracker.Comment: 10 pages, 9 figures, Accepted to AIP Advance

Littoral undersea warfare: a case study in process modelling for functionality and introperability of complex systems

The goal of this investigation is to demonstrate the application of a process modelling approach to architect a System of Systems (SoS) capable of conducting Anti-Submarine Warfare (ASW) operations projecting to the year 2025. Process modelling is a methodology for architectural analysis for complex systems whose operation is characterised by ‘processes’ whose sequential execution may be scaled-up to understand overall system behaviour. It is ideally suited to address complexity and interoperability issues of an ASW SoS. New contributions of this work include the successful implementation of a process modelling approach to architect an ASW SoS and a cohesive set of results analysing its operation with future projections to the year 2025. We believe this work may serve as a foundation for future systems engineering research addressing interoperability and performance of complex systems whose function is closely tied to time-dependent processes, with particular application to military and security systems