Phase Dependent Spectroscopy of Mira Variable Stars

Spectroscopic measurements of Mira variable stars, as a function of phase, probe the stellar atmospheres and underlying pulsation mechanisms. For example, measuring variations in TiO, VO, and ZrO with phase can be used to help determine whether these molecular species are produced in an extended region above the layers where Balmer line emission occurs or below this shocked region. Using the same methods, the Balmer-line increment, where the strongest Balmer line at phase zero is H-delta and not H-alpha can be measured and explanations tested, along with another peculiarity, the absence of the H-epsilon line in the spectra of Miras when other Balmer lines are strong. We present new spectra covering the spectral range from 6200 Angstroms to 9000 Angstroms of 20 Mira variables. A relationship between variations in the CaII IR triplet and H-alpha as a function of phase support the hypothesis that H-epsilon's observational characteristics result from an interaction of H-epsilon photons with the CaII H line. New periods and epochs of variability are also presented for each star

Exploring the Pathogenic and Drug Resistance Mechanisms of Staphylococcus aureus

We have previously identified σS, an ECF sigma factor that is important in the virulence and stress response of S. aureus. Transcriptional profiling of sigS revealed that it is differentially regulated in a variety of laboratory and clinical strains of S. aureus, suggesting that there exists a regulatory network that modulates its expression. In order to identify direct regulators of sigS expression, we performed a biotin pull down assay in tandem with mass spectrometry. We identified CymR as a direct regulator and observed that sigS expression is increased in cells lacking cymR. In addition, transposon mutagenesis was performed to identify regulators of sigS expression. We identified insertions in genes that are transcriptional regulators, and elements involved in amino acid biosynthesis and DNA replication, recombination and repair as influencing sigS expression. Finally, methyl nitro-nitrosoguanidine mutagenesis in conjunction with whole genome sequencing was employed and revealed mutations in the lactose repressor, lacR, and the membrane sensor histidine kinase, kdpD, as negatively effecting sigS expression. EMSAs revealed that LacR is an indirect regulator of sigS expression, while the response regulator KdpE is a direct repressor. These results indicate that a complex regulatory network is in place for sigS that modulates its expression. In a continuation of studies on σS regulation, we next explored interplay with the products of genes conserved within the sigS locus. We determined that this region is conserved amongst all the sequenced staphylococci, and includes four genes: SAUSA300_1721 (a conserved hypothetical protein), as well as sigS, ecfX, and ecfY. In order to investigate the relationship between EcfX and σS we performed protein pull down assays and observed that these two protein interact. Further to this, transcriptional analysis of sigS in an ecfX mutant reveal that expression of sigS is decreased, indicating that it is an activator. Architectural analysis of the sigS locus via RNAseq revealed that the majority of transcription in this region comes from ecfY, a gene that is downstream and divergent to sigS. We demonstrate that inactivation of ecfY leads to a significant increase in sigS expression, and that ecfY null strains are more resistant to DNA damaging agents such as UV, H2O2, MMS, and ethidium bromide, which we have previously demonstrated that a sigS mutant is highly sensitive to. Our studies also revealed that an ecfY null strain is better able to survive intracellularly following phagocytosis by RAW 264.7 cell and demonstrates increased survival in whole-human blood, which is again opposed to that previously observed for sigS deficient strains. Because the ecfY null strain overexpresses sigS, we investigated the regulon of this sigma factor using this mutant in conjunction with RNAseq analysis. We identified that genes putatively under the control of σS are involved in DNA damage and repair, virulence, amino acid starvation and nucleic acid biosynthesis. Collectively, our results indicate that σS is regulated via a unique mechanism: positively through an apparent need for an activator protein (EcfX) and negatively via RNA-RNA interaction (the 3’ UTR of ecfY). We suggest that the evidence presented here greatly adds not only to our understanding of the regulatory circuits extant within S. aureus, but also to alternative sigma factor biology in general. Finally, we evaluated the efficacy of a novel library of quinazoline-based compounds against a highly drug resistant strain of S. aureus. We performed structure activity and structure property relationship assays in order to identify lead compounds. These methods lead to the identification of N2,N4-disubstituted quinazoline-2,4-diamines that had low minimum inhibitory concentrations, along with favorable physiochemical properties. Evaluation of their biological activity demonstrated limited potential for resistance of to our quinazoline based compounds, low toxicity to human epithelial cells, and strong efficacy in vivo. Taken together, our findings support the use of quinazoline derivatives as potential new antimicrobials against multidrug resistant S. aureus

Development of superconducting YBa2Cu3O(x) wires with low resistance electrical contacts

Materials exhibiting superconductivity above liquid nitrogen temperatures (77 K) will enable new applications of this phenomena. One of the first commercial applications of this technology will be superconducting magnets for medical imaging. However, a large number of aerospace applications of the high temperature superconducting materials have also been identified. These include magnetic suspension and balance of models in wind tunnels and resistanceless leads to anemometers. The development of superconducting wires fabricated from the ceramic materials is critical for these applications. The progress in application of a patented fiber process developed by Clemson University for the fabrication of superconducting wires is reviewed. The effect of particle size and heat treatment on the quality of materials is discussed. Recent advances made at Christopher Newport College in the development of micro-ohm resistance electrical contacts which are capable of carrying the highest reported direct current to this material is presented

Three-Dimensional Numerical Simulations of Equatorial Spread F: Results and Observations in the Pacific Sector

A three-dimensional numerical simulation of plasma density irregularities in the postsunset equatorial F region ionosphere leading to equatorial spread F (ESF) is described. The simulation evolves under realistic background conditions including bottomside plasma shear flow and vertical current. It also incorporates C/NOFS satellite data which partially specify the forcing. A combination of generalized Rayleigh-Taylor instability (GRT) and collisional shear instability (CSI) produces growing waveforms with key features that agree with C/NOFS satellite and ALTAIR radar observations in the Pacific sector, including features such as gross morphology and rates of development. The transient response of CSI is consistent with the observation of bottomside waves with wavelengths close to 30 km, whereas the steady state behavior of the combined instability can account for the 100+ km wavelength waves that predominate in the F region

Using rhythm for rehabilitation: evaluation of a novel haptic device

This project explored how new and novel approaches to stroke rehabilitation could improve physical function and the confidence of stroke survivors to remain active and engaged in the community. The innovation trialed was a ‘Haptic bracelet/cueing device’, developed at The Open University. An overview of the Haptic device, its development and role in stroke rehabilitation can be viewed at: https://www.youtube.com/watch?v=S4ZxN6H6XGk The Haptic bracelets provide a physical (embodied) beat that someone can walk to as an alternative to existing audio cuing ways of working. The haptic device provides a non-invasive, relatively cheap way of facilitating people after stroke to continue to maintain or even improve their mobility after intensive rehabilitation has finished. This research explored the impact of the haptic device to gains in mobility. The project had two key aims: 1. To develop a usable and practical prototype of a haptic device to restore gait symmetry after stroke. 2. To investigate the feasibility and acceptability of the prototype in stroke patients. Summary of findings and recommendations When introduced to the Haptic Bracelets participants hoped the product would provide them with: • More confidence and make them feel safer when walking. • Greater ability to take bigger strides rather than little steps. • A way to combat the silly mistakes participants reported making due to tiredness. • Reduced pain (knees, hips) The physiotherapists saw potential for the Haptic devices as part of post stroke rehabilitation, but expressed concern about their lack of access to mobile technologies when out in community practice settings. There were also concerns about use with some stroke survivors because of issues of cognition; and the sensation from the Haptic beat. In the Haptic gait testing • All the participants demonstrated good mobility performance prior to the study (high score on the Rivermead mobility scale) • 4/7* (57.1%) participants who were the most asymmetrical at baseline improved their gait symmetry whilst wearing the haptic device • 3/7* (42%) participant’s gait symmetry continued to improve in the post off condition. • All the participants walked quicker in post-op condition. However, gait speed varied between participants when they were wearing the haptic bracelets. • Participants were had had their strokes between 3-10 years ago, but there was still an indication that the Haptic bracelets were having some impact on mobility. • Syncing of the Haptic device and more mobile Inertial Measurement Unit (IMU) to the fixed gait laboratory (gold standard) system has improved the potential for more community based rehabilitation and commercialisation of the Haptic bracelets. • Post Haptic interviews identified that there were mixed participant feelings about the bracelets. However, some did express positive experiences from testing the Haptic bracelets, including a carry over effect after the devices were removed. Recommendations As this was a pilot study more work is now required to explore the: • use of the Haptic bracelets in community rehabilitation settings • feasibility of the using Haptic bracelets in community settings, particularly looking at staff access to new technologies • potential for the Haptic bracelets to be used in the home as part of ongoing rehabilitation • benefits of Haptic bracelets in the context of longer term stroke rehabilitation • future design needs to improve the look, size and ease of application • cost benefits of using Haptic bracelets as part of an overall program of stroke rehabilitation

Electron transport and anisotropy of the upper critical magnetic field in a Ba0.68K0.32Fe2As2 single crystals

Early work on the iron-arsenide compounds supported the view, that a reduced dimensionality might be a necessary prerequisite for high-Tc superconductivity. Later, however, it was found that the zero-temperature upper critical magnetic field, Hc2(0), for the 122 iron pnictides is in fact rather isotropic. Here, we report measurements of the temperature dependence of the electrical resistivity, \Gamma(T), in Ba0.5K0.5Fe2As2 and Ba0.68K0.32Fe2As2 single crystals in zero magnetic field and for Ba0.68K0.32Fe2As2 as well in static and pulsed magnetic fields up to 60 T. We find that the resistivity of both compounds in zero field is well described by an exponential term due to inter-sheet umklapp electron-phonon scattering between light electrons around the M point to heavy hole sheets at the \Gamma point in reciprocal space. From our data, we construct an H-T phase diagram for the inter-plane (H || c) and in-plane (H || ab) directions for Ba0.68K0.32Fe2As2. Contrary to published data for underdoped 122 FeAs compounds, we find that Hc2(T) is in fact anisotropic in optimally doped samples down to low temperatures. The anisotropy parameter, {\gamma} = Habc2/Hcc2, is about 2.2 at Tc. For both field orientations we find a concave curvature of the Hc2 lines with decreasing anisotropy and saturation towards lower temperature. Taking into account Pauli spin paramagnetism we perfectly can describe Hc2(T) and its anisotropy.Comment: 7 pages, 3 figure

The Red Sea, Coastal Landscapes, and Hominin Dispersals

This chapter provides a critical assessment of environment, landscape and resources in the Red Sea region over the past five million years in relation to archaeological evidence of hominin settlement, and of current hypotheses about the role of the region as a pathway or obstacle to population dispersals between Africa and Asia and the possible significance of coastal colonization. The discussion assesses the impact of factors such as topography and the distribution of resources on land and on the seacoast, taking account of geographical variation and changes in geology, sea levels and palaeoclimate. The merits of northern and southern routes of movement at either end of the Red Sea are compared. All the evidence indicates that there has been no land connection at the southern end since the beginning of the Pliocene period, but that short sea crossings would have been possible at lowest sea-level stands with little or no technical aids. More important than the possibilities of crossing the southern channel is the nature of the resources available in the adjacent coastal zones. There were many climatic episodes wetter than today, and during these periods water draining from the Arabian escarpment provided productive conditions for large mammals and human populations in coastal regions and eastwards into the desert. During drier episodes the coastal region would have provided important refugia both in upland areas and on the emerged shelves exposed by lowered sea level, especially in the southern sector and on both sides of the Red Sea. Marine resources may have offered an added advantage in coastal areas, but evidence for their exploitation is very limited, and their role has been over-exaggerated in hypotheses of coastal colonization

Methodological considerations in the analysis of fecal glucocorticoid metabolites in tufted capuchins (Cebus apella)

Analysis of fecal glucocorticoid (GC) metabolites has recently become the standard method to monitor adrenocortical activity in primates noninvasively. However, given variation in the production, metabolism, and excretion of GCs across species and even between sexes, there are no standard methods that are universally applicable. In particular, it is important to validate assays intended to measure GC production, test extraction and storage procedures, and consider the time course of GC metabolite excretion relative to the production and circulation of the native hormones. This study examines these four methodological aspects of fecal GC metabolite analysis in tufted capuchins (Cebus apella). Specifically, we conducted an adrenocorticotrophic hormone (ACTH) challenge on one male and one female capuchin to test the validity of four GC enzyme immunoassays (EIAs) and document the time course characterizing GC me- tabolite excretion in this species. In addition, we compare a common field-friendly technique for extracting fecal GC metabolites to an established laboratory extraction methodology and test for effects of storing “field extracts” for up to 1 yr. Results suggest that a corticosterone EIA is most sensitive to changes in GC production, provides reliable measures when extracted according to the field method, and measures GC metabolites which remain highly stable after even 12 mo of storage. Further, the time course of GC metabolite excretion is shorter than that described yet for any primate taxa. These results provide guidelines for studies of GCs in tufted capuchins, and underscore the importance of validating methods for fecal hormone analysis for each species of interest

High accuracy measurement of gravitational wave back-reaction in the OJ287 black hole binary

Blazar OJ287 exhibits large thermal flares at least twice every 12 years. The times of these flares have been predicted successfully using the model of a quasi-Keplerian eccentric black hole binary where the secondary impacts the accretion disk of the primary, creating the thermal flares. New measurements of the historical light curve have been combined with the observations of the 2015 November/December flare to identify the impact record since year 1886, and to constrain the orbit of the binary. The orbital solution shows that the binary period, now 12.062 years, is decreasing at the rate of 36 days per century. This corresponds to an energy loss to gravitational waves that is 6.5 ± 4 % less than the rate predicted by the standard quadrupolar gravitational wave (GW) emission. We show that the difference is due to higher order gravitational radiation reaction terms that include the dominant order tail contributions

Ground and Space-Based Measurement of Rocket Engine Burns in the Ionosphere

On-orbit firings of both liquid and solid rocket motors provide localized disturbances to the plasma in the upper atmosphere. Large amounts of energy are deposited to ionosphere in the form of expanding exhaust vapors which change the composition and flow velocity. Charge exchange between the neutral exhaust molecules and the background ions (mainly O+) yields energetic ion beams. The rapidly moving pickup ions excite plasma instabilities and yield optical emissions after dissociative recombination with ambient electrons. Line-of-sight techniques for remote measurements rocket burn effects include direct observation of plume optical emissions with ground and satellite cameras, and plume scatter with UHF and higher frequency radars. Long range detection with HF radars is possible if the burns occur in the dense part of the ionosphere. The exhaust vapors initiate plasma turbulence in the ionosphere that can scatter HF radar waves launched from ground transmitters. Solid rocket motors provide particulates that become charged in the ionosphere and may excite dusty plasma instabilities. Hypersonic exhaust flow impacting the ionospheric plasma launches a low-frequency, electromagnetic pulse that is detectable using satellites with electric field booms. If the exhaust cloud itself passes over a satellite, in situ detectors measure increased ion-acoustic wave turbulence, enhanced neutral and plasma densities, elevated ion temperatures, and magnetic field perturbations. All of these techniques can be used for long range observations of plumes in the ionosphere. To demonstrate such long range measurements, several experiments were conducted by the Naval Research Laboratory including the Charged Aerosol Release Experiment, the Shuttle Ionospheric Modification with Pulsed Localized Exhaust experiments, and the Shuttle Exhaust Ionospheric Turbulence Experiments