Essence in the philosophy of George Santayana.

Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1954 .D6. Source: Masters Abstracts International, Volume: 40-07, page: . Thesis (M.A.)--University of Windsor (Canada), 1954

Effect of hydrogen on deformation structure and properties of CMSX-2 nickel-base single-crystal superalloy

Material used in this study was a heat of the alloy CMSX-2. This nickel-based superalloy was provided in the form of oriented single crystals, solutionized for 3 hrs at 1315 C. It was then usually heat treated as follows: 1050 C/16h/air cool + 850 C/48h/air cool. The resulting microstructure is dominated by cuboidal, ordered gamma precipitates with a volume fraction of about 75% and an average size of 0.5 microns. In brief, the most compelling hydrogen induced-changes in deformation structure are: (1) enhanced dislocation accumulation in the gamma matrix; and (2) more extensive cross-slip of superdislocations in the gamma precipitates. The enhanced dislocation density in gamma acts to decrease the mean free path of a superdislocation, while easier cross slip hinders superdislocation movement by providing pinning points in the form of sessile jobs. Both processes contribute to the increase of flow stress and the notable work hardening that occurs prior to fracture

The Unexpected Role of Evolving Longitudinal Electric Fields in Generating Energetic Electrons in Relativistically Transparent Plasmas

Superponderomotive-energy electrons are observed experimentally from the interaction of an intense laser pulse with a relativistically transparent target. For a relativistically transparent target, kinetic modeling shows that the generation of energetic electrons is dominated by energy transfer within the main, classically overdense, plasma volume. The laser pulse produces a narrowing, funnel-like channel inside the plasma volume that generates a field structure responsible for the electron heating. The field structure combines a slowly evolving azimuthal magnetic field, generated by a strong laser-driven longitudinal electron current, and, unexpectedly, a strong propagating longitudinal electric field, generated by reflections off the walls of the funnel-like channel. The magnetic field assists electron heating by the transverse electric field of the laser pulse through deflections, whereas the longitudinal electric field directly accelerates the electrons in the forward direction. The longitudinal electric field produced by reflections is 30 times stronger than that in the incoming laser beam and the resulting direct laser acceleration contributes roughly one third of the energy transferred by the transverse electric field of the laser pulse to electrons of the super-ponderomotive tail

High‐Intensity Laser Triggered Proton Acceleration from Ultrathin Foils

The recently developed PIC code MANDOR features arbitrary target design including 3D preplasma and the 6‐component laser fields of a tightly focused laser beam. The 3D simulations have been performed to model recent HERCULES experiments on proton acceleration, where protons with energy greater than 20 MeV were produced using just 1.5 J laser pulses focused to intensity of 2 × 10 21 W/cm 2 . By adapting the 3D target geometry relating to ps‐prepulse effect, reasonable agreement with experimental data for the proton energy spectrum has been achieved. The effect of the 3D preplasma shape on efficiency of proton acceleration is discussed. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/96347/1/161_ftp.pd

Progress in Short Period Multilayer Coatings for Water Window Applications

Absolute photoionization cross-section measurements for amixture of ground and metastable states of Xe4+, Xe5+, and Xe6+ arereported in the photon energy range of 4d-nf transitions, which occurwithin or adjacent to the 13.5 nm window for extreme ultravioletlithography light source development. The reported values allow thequantification of opacity effects in xenon plasmas due to these 4d-4fautoionizing states. The oscillator strengths for the 4d-4f and 4d-5ftransitions in Xeq+ (q=1-6) ions are calculated using nonrelativisticHartree-Fock and random phase approximations. These are compared withpublished experimental values for Xe+ to Xe3+ and with the valuesobtained from the present experimental cross-section measurements forXe4+ to Xe6+. The calculations assisted in the determination of themetastable content in the ion beams for Xe5+T and Xe6+. The experimentswere performed by merging a synchrotron photon beam generated by anundulator beamline of the Advanced Light Source with an ion beam producedby an electron cyclotron resonance ion source

A Bright Spatially-Coherent Compact X-ray Synchrotron Source

Each successive generation of x-ray machines has opened up new frontiers in science, such as the first radiographs and the determination of the structure of DNA. State-of-the-art x-ray sources can now produce coherent high brightness keV x-rays and promise a new revolution in imaging complex systems on nanometre and femtosecond scales. Despite the demand, only a few dedicated synchrotron facilities exist worldwide, partially due the size and cost of conventional (accelerator) technology. Here we demonstrate the use of a recently developed compact laser-plasma accelerator to produce a well-collimated, spatially-coherent, intrinsically ultrafast source of hard x-rays. This method reduces the size of the synchrotron source from the tens of metres to centimetre scale, accelerating and wiggling a high electron charge simultaneously. This leads to a narrow-energy spread electron beam and x-ray source that is >1000 times brighter than previously reported plasma wiggler and thus has the potential to facilitate a myriad of uses across the whole spectrum of light-source applications.Comment: 5 pages, 4 figure

Wildlife hunting in complex human-environmental systems: How understanding natural resource use and human welfare can improve conservation in the Ankarafantsika National Park, Madagascar

Conservation officials work to manage complex and interacting human-environmental systems, where balancing needs between the two systems can become a source of tension. This study presents information on the use of natural resources by, and the health and welfare of, rural  communities within and near Ankarafantsika National Park (ANP) in northwestern Madagascar. We focus on behaviors that are difficult for natural resource managers to measure themselves, including the hunting of threatened and protected wildlife and on sensitive information about humanwealth, health, and food security. We surveyed 41 9 households and measured the health of 1 860 individuals in 1 8 communities adjacent to or within the boundaries of ANP. We found a very high prevalence of child malnutrition, illness, and food insecurity and a heavy reliance on natural products to meet subsistence needs. More than 90% of the population reported that they hunted wildlife and harvested wild vegetables at least one day during the prior week as a direct means to cope with their food insecurity. Further, we found a high reliance on the forest for both healthcare and the building of adequate shelter. Efforts to improve overall food security would likely improve both human welfare and the long-term conservation of the threatened wildlife and habitat of Ankarafantsika. These data can help both conservation and community livelihood programs to find integrated solutions to the shared challenges of improving the well-being of human populations and the protection of Madagascar’s unique, endemic, and highly threatened biodiversity.   Les gestionnaires oeuvrant pour la protection de la nature sont généralement confrontés à des systèmes socio-écologiques complexes et interactifs dans lesquels la recherche de l’équilibre entre les besoins de ces deux systèmes peut s’avérer être une source de tension. Cette étude présente des informations sur l'utilisation des ressources naturelles par les communautés rurales riveraines du parc national d'Ankarafantsika (PNA) dans le nord-ouest de Madagascar, ainsi que sur la santé et le bien-être de ces communautés. L’étude s’est en particulier orientée sur les comportementsdifficiles à mesurer pour les gestionnaires de ressources naturelles, à savoir la chasse d'animaux sauvages menacés et protégés et les informations portant sur l’opulence, la santé et la sécurité alimentaire des gens. Une enquête a été réalisée auprès de 41 9 ménages et l’état de santé de 1 860 personnes a été mesuré dans 1 8 communautés vivant à la périphérie ou à l’intérieur des limites du PNA. Une très forte prévalence de la  malnutrition infantile a été observée ainsi que diverses pathologies, une insécurité alimentaire et une dépendance importante à l'égard des produits naturels pour répondre aux besoins de subsistance. Plus de 90% de la population a déclaré qu'elle avait chassé des animaux et récolté des plantes sauvages au moins un jour au cours de la semaine précédente, à titre de moyen direct pour faire face à l' insécurité alimentaire. Une forte dépendance à l'égard des forêts a également été notée pour les produits destinés à la santé et la construction de maisons. Les efforts visant à améliorer la sécurité alimentaire dans son ensemble pourraient vraisemblablement améliorer le bien-être humain aussi bien que la conservationà long terme de la faune et des habitats menacés de l'Ankarafantsika. Ces données peuvent aider les programmes de conservation et de subsistance de la communauté à trouver des solutions intégrées aux problèmes communs de l’amélioration du bien-être des populations humaines et de la protection de la biodiversité unique, endémique et hautement menacée de Madagascar

Control of proton energy in ultra-high intensity laser-matter interaction

Recent breakthroughs in short pulse laser technology resulted in (i) generation of ultra-high intensity (2×1022 W/cm2) and (ii) ultra-high contrast (10−11) short pulses at the Hercules facility of the University of Michigan, which has created the possibility of exploring a new regime of ion acceleration – the regime of Directed Coulomb Explosion (DCE). In this regime of sufficiently high laser intensities and target thicknesses approaching the relativistic plasma skin depth it is possible to expel electrons from the target focal volume by the laser's ponderomotive force allowing for direct laser ion acceleration combined with a Coulomb explosion. That results in greater than 100 MeV protons with a quasi-monoenergetic energy spectrum. The utilization of beam shaping, namely, the use of flat-top beams, leads to more efficient proton acceleration due to the increase of the longitudinal field. According to the results of 2D PIC simulations a 500 TW laser pulse with a super-Gaussian beam profile interacting with 0.1 micron aluminium-hydrogen foil is able to produce monoenergetic protons with the energy up to 240 MeV.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/85403/1/jpconf10_244_042025.pd