Isotropic-medium three-dimensional cloaks for acoustic and electromagnetic waves

We propose a generalization of the two-dimensional eikonal-limit cloak derived from a conformal transformation to three dimensions. The proposed cloak is a spherical shell composed of only isotropic media; it operates in the transmission mode and requires no mirror or ground plane. Unlike the well-known omnidirectional spherical cloaks, it may reduce visibility of an arbitrary object only for a very limited range of observation angles. In the short-wavelength limit, this cloaking structure restores not only the trajectories of incident rays, but also their phase, which is a necessary ingredient to complete invisibility. Both scalar-wave (acoustic) and transverse vector-wave (electromagnetic) versions are presented.Comment: 17 pages, 12 figure

Influence of drainage divides versus arid corridors on genetic structure and demography of a widespread freshwater turtle, Emydura macquarii krefftii, from Australia

The influence of Pleistocene climatic cycles on Southern Hemisphere biotas is not yet well understood. Australia's eastern coastal margin provides an ideal setting for examining the relative influence of landscape development, sea level fluctuation, and cyclic climatic aridity on the evolution of freshwater biodiversity. We examined the impact of climatic oscillations and physical biogeographic barriers on the evolutionary history of the wide-ranging Krefft's river turtle (Emydura macquarii krefftii), using range-wide sampling (649 individuals representing 18 locations across 11 drainages) and analysis of mitochondrial sequences (similar to 1.3-kb control region and ND4) and nuclear microsatellites (12 polymorphic loci). A range of phylogeographic (haplotype networks, molecular dating), demographic (neutrality tests, mismatch distributions), and population genetic analyses (pairwise F-ST, analysis of molecular variance, Bayesian clustering analysis) were implemented to differentiate between competing demographic (local persistence vs. range expansion) and biogeographic (arid corridor vs. drainage divide) scenarios. Genetic data reveal population genetic structure in Krefft's river turtles primarily reflects isolation across drainage divides. Striking north-south regional divergence (2.2% ND4 p-distance; c. 4.73Ma, 95% higher posterior density (HPD) 2.08-8.16Ma) was consistent with long-term isolation across a major drainage divide, not an adjacent arid corridor. Ancient divergence among regional lineages implies persistence of northern Krefft's populations despite the recurrent phases of severe local aridity, but with very low contemporary genetic diversity. Stable demography and high levels of genetic diversity are inferred for southern populations, where aridity was less extreme. Range-wide genetic structure in Krefft's river turtles reflects contemporary and historical drainage architecture, although regional differences in the extent of Plio-Pleistocene climatic aridity may be reflected in current levels of genetic diversity

Predicting the Reactions of CS2 with Group IV and Group VI Transition Metal Oxides

Building onto a recent serious of ab initio studies of various acid-gas reactions with metal oxide sorbents, electronic structure methods are being used to study the addition of CS₂ to Group IV (MO₂)ₙ and Group VI (MO₃)ₙ (n = 1, 2, 3) nanoclusters, beginning with the MO₂ and MO₃ monomers according to a “bottom-up” approach. The preliminary density functional theory (DFT) calculations in this study provide structures and vibrational frequency thermodynamic corrections for later expanding upon by way of single point correlated molecular-orbital theory (MO) calculations, mainly CCSD(T) and MP2 to study the structures and energies which could arise from Lewis acid-base addition (physisorption) and formation of COS₂²⁻ (chemisorption) of CS₂ to these clusters will be predicted. For future work, these CS₂ ligand binding energies (LBE) will be compared to established CO₂ results in the literature and to any known experimental and computational values for the interactions of CS₂ with bulk metal oxides. These LBEs will then be analyzed for any correlation to any known trends in the metal oxide Lewis acidity, metal oxide redox chemistry, and acid gas basicity to establish useful thermodynamic benchmarks for the practicality of Group IV and Group VI transition metal oxides for the sequestration and conversion of CS₂. The results of this work and beyond could also have serious implications for the sequestration of CS₂ from high-sulfur areas of the arctic permafrost and could provide valuable mechanistic insights into the possible reactions and products of metal oxide degradation during the Claus Process.https://scholarworks.moreheadstate.edu/celebration_posters_2023/1062/thumbnail.jp

The current state of biomarker research for Friedreich's ataxia: a report from the 2018 FARA biomarker meeting

The 2018 FARA Biomarker Meeting highlighted the current state of development of biomarkers for Friedreich's ataxia. A mass spectroscopy assay to sensitively measure mature frataxin (reduction of which is the root cause of disease) is being developed. Biomarkers to monitor neurological disease progression include imaging, electrophysiological measures and measures of nerve function, which may be measured either in serum and/or through imaging-based technologies. Potential pharmacodynamic biomarkers include metabolic and protein biomarkers and markers of nerve damage. Cardiac imaging and serum biomarkers may reflect cardiac disease progression. Considerable progress has been made in the development of biomarkers for various contexts of use, but further work is needed in terms of larger longitudinal multisite studies, and identification of novel biomarkers for additional use cases

Convergence and Interdependence at the Civil-Military Interface

http://deepblue.lib.umich.edu/bitstream/2027.42/50870/1/91.pd

MIT SchMUSE: Class-Based Remote Delegation in a Capricious Distributed Environment

MIT SchMUSE (pronounced "shmooz") is a concurrent, distributed, delegation-based object-oriented interactive environment with persistent storage. It is designed to run in a "capricious" network environment, where servers can migrate from site to site and can regularly become unavailable. Our design introduces a new form of unique identifiers called "globally unique tickets" that provide globally unique time/space stamps for objects and classes without being location specific. Object location is achieved by a distributed hierarchical lazy lookup mechanism that we call "realm resolution." We also introduce a novel mechanism called "message deferral" for enhanced reliability in the face of remote delegation. We conclude with a comparison to related work and a projection of future work on MIT SchMUSE

Summed Parallel Infinite Impulse Response (SPIIR) Filters For Low-Latency Gravitational Wave Detection

With the upgrade of current gravitational wave detectors, the first detection of gravitational wave signals is expected to occur in the next decade. Low-latency gravitational wave triggers will be necessary to make fast follow-up electromagnetic observations of events related to their source, e.g., prompt optical emission associated with short gamma-ray bursts. In this paper we present a new time-domain low-latency algorithm for identifying the presence of gravitational waves produced by compact binary coalescence events in noisy detector data. Our method calculates the signal to noise ratio from the summation of a bank of parallel infinite impulse response (IIR) filters. We show that our summed parallel infinite impulse response (SPIIR) method can retrieve the signal to noise ratio to greater than 99% of that produced from the optimal matched filter. We emphasise the benefits of the SPIIR method for advanced detectors, which will require larger template banks.Comment: 9 pages, 6 figures, for PR

Hydrocarbon Biogeochemical Setting of the Baffin Island Oil Spill Experimental Sites. II. Water

A baseline for petroleum residues in the waters of the Cape Hatt region of Baffin Island in arctic Canada was obtained in anticipation of controlled oil releases of the Baffin Island Oil Spill (BIOS) Project. Total aliphatic and aromatic residues reflecting multiple sources were found to be in the low to sub micro g/l concentrations range. Alkylated naphthalenes, phenanthrenes and dibenzothiophenes were present in the sub ng/l concentrations range. The hydrocarbon baseline for the waters of the BIOS study area was found to be as low as might be found anywhere on earth and therefore ideally suited to the BIOS study.Key words: BIOS, arctic marine Canada, hydrocarbon baseline, waterMots clés: BIOS, Arctique marin canadien, niveau de référence d’hydrocarbures, ea