110 research outputs found

    Linking goniometer measurements to hyperspectral and multi-sensor imagery for retrieval of beach properties and coastal characterization

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    In June 2011, a multi-sensor airborne remote sensing campaign was flown at the Virginia Coast Reserve Long Term Ecological Research site with coordinated ground and water calibration and validation (cal/val) measurements. Remote sensing imagery acquired during the ten day exercise included hyperspectral imagery (CASI-1500), topographic LiDAR, and thermal infra-red imagery, all simultaneously from the same aircraft. Airborne synthetic aperture radar (SAR) data acquisition for a smaller subset of sites occurred in September 2011 (VCR\u2711). Focus areas for VCR\u2711 were properties of beaches and tidal flats and barrier island vegetation and, in the water column, shallow water bathymetry. On land, cal/val emphasized tidal flat and beach grain size distributions, density, moisture content, and other geotechnical properties such as shear and bearing strength (dynamic deflection modulus), which were related to hyperspectral BRDF measurements taken with the new NRL Goniometer for Outdoor Portable Hyperspectral Earth Reflectance (GOPHER). This builds on our earlier work at this site in 2007 related to beach properties and shallow water bathymetry. A priority for VCR\u2711 was to collect and model relationships between hyperspectral imagery, acquired from the aircraft at a variety of different phase angles, and geotechnical properties of beaches and tidal flats. One aspect of this effort was a demonstration that sand density differences are observable and consistent in reflectance spectra from GOPHER data, in CASI hyperspectral imagery, as well as in hyperspectral goniometer measurements conducted in our laboratory after VCR\u2711

    Comparison of baroreflex sensitivity with a fall and rise in blood pressure induced by the Valsalva manoeuvre

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    Abstract The baroreflex plays a key role in human BP (blood pressure) regulation. Its efferent limb consists of a vagal and a sympathetic component. The Valsalva manoeuvre is widely used to quantify vagal baroreflex function [BRS_vagal (vagal baroreflex sensitivity)], but most studies have focused on the R-R interval response to BP decrement, even though the subsequent response to an increment in BP is important and different. In the present study, we sought to evaluate whether BRS_vagal can be determined from BRSvagal inc (BRS_vagal derived from the rise in BP during phases III-IV of the Valsalva manoeuvre), to assess the association between BRSvagal inc and BRSvagal dec (BRS_vagal derived from the preceeding BP decrement) and to validate BRSvagal inc as an index of autonomic function. We studied patients with severe autonomic failure (n = 49, 25 female), mild autonomic failure (n = 25, 11 female) and matched normal controls (n = 29, 15 female). BRSvagal inc and BRSvagal dec were calculated as the regression slope of R-R interval and systolic BP during phases III-IV and the early phase II of the Valsalva manoeuvre respectively, and compared these with other autonomic indices across the groups. BRSvagal inc was calculated in all subjects and correlated highly with BRSvagal dec (r = 0.72, P < 0.001). BRSvagal inc also correlated significantly with BP changes during phases II and IV of the Valsalva manoeuvre and sympathetic barosensitivity. BRSvagal inc was significantly different between the groups, being highest in the controls and lowest in patients with severe autonomic failure. In conclusion, vagal BRS, determined by relating R-R interval with the BP increase following phase III, is a valuable autonomic index, provides additional information about vagal baroreflex function and reflects overall severity of autonomic failure

    Scalable Multispecies Ion Transport in a Grid Based Surface-Electrode Trap

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    We present a scalable method for the control of ion crystals in a grid-based surface electrode Paul trap and characterize it in the context of transport operations that sort and reorder multispecies crystals. By combining co-wiring of control electrodes at translationally symmetric locations in each grid site with the site-wise ability to exchange the voltages applied to two special electrodes gated by a binary input, site-dependent operations are achieved using only a fixed number of analog voltage signals and a single digital input per site. In two separate experimental systems containing nominally identical grid traps, one using 171Yb+^{171}\mathrm{Yb}^{+}-138Ba+^{138}\mathrm{Ba}^{+} crystals and the other 137Ba+^{137}\mathrm{Ba}^{+}-88Sr+^{88}\mathrm{Sr}^{+}, we demonstrate this method by characterizing the conditional intra-site crystal reorder and the conditional exchange of ions between adjacent sites on the grid. Averaged across a multi-site region of interest, we measure sub-quanta motional excitation in the axial in-phase and out-of-phase modes of the crystals following these operations at exchange rates of 2.5 kHz. These conditional transport operations display all necessary components for sorting qubits, and could be extended to implement other conditional operations involving control fields such as gates, initialization, and measurement.Comment: 11 pages, 7 figure

    Drying colloidal systems: laboratory models for a wide range of applications

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    The drying of complex fluids provides a powerful insight into phenomena that take place on time and length scales not normally accessible. An important feature of complex fluids, colloidal dispersions and polymer solutions is their high sensitivity to weak external actions. Thus, the drying of complex fluids involves a large number of physical and chemical processes. The scope of this review is the capacity to tune such systems to reproduce and explore specific properties in a physics laboratory. A wide variety of systems are presented, ranging from functional coatings, food science, cosmetology, medical diagnostics and forensics to geophysics and art

    African hydroclimatic variability during the last 2000 years

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