Optical Magnetometer Array for Fetal Magnetocardiography

We describe an array of spin-exchange relaxation free optical magnetometers designed for detection of fetal magnetocardiography (fMCG) signals. The individual magnetometers are configured with a small volume with intense optical pumping, surrounded by a large pump-free region. Spin-polarized atoms that diffuse out of the optical pumping region precess in the ambient magnetic field and are detected by a probe laser. Four such magnetometers, at the corners of a 7 cm square, are configured for gradiometry by feeding back the output of one magnetometer to a field coil to null uniform magnetic field noise at frequencies up to 200 Hz. Using this array, we present the first measurements of fMCG signals using an atomic magnetometer

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Development and Flammability Testing of Magnesium Alloys for Space Applications

This project will be comparing the flammability of select lightweight Mg alloys for use in a simulated ISS environment. It will also be determining the factors that influence flammability of selected alloys in elevated oxygen, including the formation of an oxide layer. The significance of this work is that such alloys can reduce weight saving by up to 30%. This work is adding to knowledge base of lightweight Mg alloys for possible future applications, as no previous flammability testing of Mg alloys have been conducted at elevated oxygen concentrations

Phosphorus Mitigation to Control River Eutrophication: Murky Waters, Inconvenient Truths, and “Postnormal” Science

This commentary examines an "inconvenient truth" that phosphorus (P)-based nutrient mitigation, long regarded as the key tool in eutrophication management, in many cases has not yet yielded the desired reductions in water quality and nuisance algal growth in rivers and their associated downstream ecosystems. We examine why the water quality and aquatic ecology have not recovered, in some case aft er two decades or more of reduced P inputs, including (i) legacies of past land-use management, (ii) decoupling of algal growth responses to river P loading in eutrophically impaired rivers; and (iii) recovery trajectories, which may be nonlinear and characterized by thresholds and alternative stable states. It is possible that baselines have shifted and that some disturbed river environments may never return to predisturbance conditions or may require P reductions below those that originally triggered ecological degradation. We discuss the practical implications of setting P-based nutrient criteria to protect and improve river water quality and ecology, drawing on a case study from the Red River Basin in the United States. We conclude that the challenges facing nutrient management and eutrophication control bear the hallmarks of "postnormal" science, where uncertainties are large, management intervention is urgently required, and decision stakes are high. We argue a case for a more holistic approach to eutrophication management that includes more sophisticated regime-based nutrient criteria and considers other nutrient and pollutant controls and river restoration (e.g., physical habitat and functional food web interactions) to promote more resilient water quality and ecosystem functioning along the land-freshwater continuum

TIRS Flood Source Calibration

Part of the calibration of the Thermal Infrared Sensor (TIRS) currently on the Landsat Data Continuity Mission was performed using the TIRS Flood Source, a 16” diameter blackbody. This presentation discusses the calibration of the TIRS Flood Source for absolute radiance after the Flood Source had been used to calibrate TIRS. The Flood source calibration was performed at Space Dynamics Lab (SDL) by comparing the output of the Flood Source to the SDL Long Wave Infrared Calibration Source (LWIRCS) blackbody using the SDL transfer radiometer (SDL-XR). LWIRCS is a calibrated, high-emissivity, 2 to 100 micron blackbody and the SDL-XR is a combination radiometer and spectrometer that was used in spectrometer mode with a filter that included the 10.8 and 12 micron TIRS bands. The Flood Source radiance was measured at 10 temperatures from 240 to 345 K, and at several horizontal positions and at several incidence angles. Flood Source effective emissivity was found to be 0.992+/-0.003 at all temperatures with no variation in horizontal position or incidence angle

Threats to coral reefs of Bermuda

Bermuda’s reefs have endured the impact of 400 years of human settlement and resource extraction. Although the reef system has benefited from pro-active regulation and control of fishing and pollution since the twentieth century, the nearshore environment and lagoon reefs are threatened by ongoing and planned activities. Coastal development, including cruise ship ports, marinas and shipping channel expansion are significant potential threats through reef removal and sedimentation. The dense human population on Bermuda has produced chronic chemical and nutrient pollution in nearshore bays and harbours. Sewage has reduced water quality in some enclosed bays but is generally not a major threat. Coral bleaching has occurred repeatedly since the 1980s, in response to elevated seawater temperatures, but these events have not resulted in significant mortality. Corals diseases are prevalent at low levels of infection in a large number of species but do not appear to have caused significant mortality. The invasive lionfish (Pterios volitans) is present and the population is growing but culling and harvesting efforts are conducted. There is great concern for the potential impacts of climate-related changes, in particular ocean acidification. Bermuda’s corals grow at reduced rates compared with Caribbean conspecifics and there is evidence that some corals are already growing slower, under the current condition of declining aragonite saturation state in reef waters. The potential for reduced coral and reef growth, in combination with rising sea level, may compromise the effectiveness of the reef as a natural barrier to storm waves, resulting in greater coastal erosion.<br/

Absence of arterial baroreflex modulation of skin sympathetic activity and sweat rate during whole-body heating in humans

Prior findings suggest that baroreflexes are capable of modulating skin blood flow, but the effects of baroreceptor loading/unloading on sweating are less clear. Therefore, this project tested the hypothesis that pharmacologically induced alterations in arterial blood pressure in heated humans would lead to baroreflex-mediated changes in both skin sympathetic nerve activity (SSNA) and sweat rate.In seven subjects mean arterial blood pressure was lowered (≈8 mmHg) and then raised (≈13 mmHg) by bolus injections of sodium nitroprusside and phenylephrine, respectively. Moreover, in a separate protocol, arterial blood pressure was reduced via steady-state administration of sodium nitroprusside. In both normothermia and heat-stress conditions the following responses were monitored: sublingual and mean skin temperatures, heart rate, beat-by-beat blood pressure, skin blood flow (laser-Doppler flowmetry), local sweat rate and SSNA (microneurography from peroneal nerve).Whole-body heating increased skin and sublingual temperatures, heart rate, cutaneous blood flow, sweat rate and SSNA, but did not change arterial blood pressure. Heart rate was significantly elevated (from 74 ± 3 to 92 ± 4 beats min−1; P < 0.001) during bolus sodium nitroprusside-induced reductions in blood pressure, and significantly reduced (from 92 ± 4 to 68 ± 4 beats min−1; P < 0.001) during bolus phenylephrine-induced elevations in blood pressure, thereby demonstrating normal baroreflex function in these subjects.Neither SSNA nor sweat rate was altered by rapid (bolus infusion) or sustained (steady-state infusion) changes in blood pressure regardless of the thermal condition.These data suggest that SSNA and sweat rate are not modulated by arterial baroreflexes in normothermic or moderately heated individuals