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1

Interferometric determination of the topographies of absolute sphere radii using the sphere interferometer of PTB  

NASA Astrophysics Data System (ADS)

This paper presents a method to reconstruct the absolute shape of a sphere—i.e. a topography of radii—using the sphere interferometer of PTB in combination with a stitching approach. The method allows for the reconstruction of absolute radii instead of the relative shape deviations which result from conventional sphericity measurements. The sphere interferometer was developed for the volume determination of spherical material measures—in particular the spheres of the Avogadro project—by precise diameter measurements with an uncertainty of 1 nm or less. In the scope of the present work a procedure has been implemented that extends the applicability of the interferometer to fields where not the volume or diameter but the direction-dependent radii are of interest. The results of the reconstruction were compared quantitatively to the independent results of sphericity measurements from CSIRO.

Bartl, Guido; Krystek, Michael; Nicolaus, Arnold; Giardini, Walter

2010-11-01

2

Curvature sensor for the measurement of the static corneal topography and the dynamic tear film topography in the human eye  

NASA Astrophysics Data System (ADS)

A system to measure the topography of the first optical surface of the human eye noninvasively by using a curvature sensor is described. The static corneal topography and the dynamic topography of the tear film can both be measured, and the topographies obtained are presented. The system makes possible the study of the dynamic aberrations introduced by the tear film to determine their contribution to the overall ocular aberrations in healthy eyes, eyes with corneal pathologies, and eyes wearing contact lenses.

Gruppetta, Steve; Koechlin, Laurent; Lacombe, François; Puget, Pascal

2005-10-01

3

Study of the tear topography dynamics using a lateral shearing interferometer  

E-print Network

topography/index.htm Abstract: The dynamics of the pre-corneal tear film topography are studied on 21Study of the tear topography dynamics using a lateral shearing interferometer Alfredo Dubra in quantitative tear topography estimation. Based on the reconstructed tear topography maps, the effects of tear

Dainty, Chris

4

Evolution of Neogene Dynamic Topography in Africa  

NASA Astrophysics Data System (ADS)

The characteristic basins and swells of Africa's surface topography probably reflect patterns of convective circulation in the sub-lithospheric mantle. We have interrogated drainage networks to determine the spatial and temporal pattern of convectively driven uplift. ~560 longitudinal river profiles were extracted from a digital elevation model of Africa. An inverse model is then used to minimise the misfit between observed and calculated river profiles as a function of uplift rate history. During inversion, the residual misfit decreases from ~22 to ~5. Our results suggest that Africa's topography began to grow most rapidly after ~30 Ma at peak uplift rates of 0.1-0.15 mm/yr. The algorithm resolves distinct phases of uplift which generate localized swells of high topography and relief (e.g. the Angolan Dome). Uplift rate histories are shown to vary significantly from swell to swell. The calculated magnitudes, timing, and location of uplift agree well with local independent geological constraints, such as intense volcanism at Hoggar (42-39 Ma) and Afar (31-29 Ma), uplifted marine terraces, and warped peneplains. We have also calculated solid sediment flux histories for major African deltas which have persisted through time. This onshore record provides an important indirect constraint on the history of vertical motions at the surface, and agrees well with the offshore flux record, obtained from mapping isopachs of deltaic sediments. Our modelling and reconstructed sedimentary flux histories indicate that the evolution of drainage networks may contain useful information about mantle convective processes.

Paul, Jonathan; Roberts, Gareth; White, Nicky

2013-04-01

5

Dynamic and reversible surface topography influences cell morphology.  

PubMed

Microscale and nanoscale surface topography changes can influence cell functions, including morphology. Although in vitro responses to static topography are novel, cells in vivo constantly remodel topography. To better understand how cells respond to changes in topography over time, we developed a soft polyacrylamide hydrogel with magnetic nickel microwires randomly oriented in the surface of the material. Varying the magnetic field around the microwires reversibly induced their alignment with the direction of the field, causing the smooth hydrogel surface to develop small wrinkles; changes in surface roughness, ?RRMS , ranged from 0.05 to 0.70 ?m and could be oscillated without hydrogel creep. Vascular smooth muscle cell morphology was assessed when exposed to acute and dynamic topography changes. Area and shape changes occurred when an acute topographical change was imposed for substrates exceeding roughness of 0.2 ?m, but longer-term oscillating topography did not produce significant changes in morphology irrespective of wire stiffness. These data imply that cells may be able to use topography changes to transmit signals as they respond immediately to changes in roughness. PMID:23355509

Kiang, Jennifer D; Wen, Jessica H; del Álamo, Juan C; Engler, Adam J

2013-08-01

6

Causes and Consequences of Time-Varying Dynamic Topography  

NASA Astrophysics Data System (ADS)

Convective circulation of the Earth's mantle maintains plate motion but we know little about the spatial and temporal details of this circulation. Accurate maps of the spatial and temporal pattern of dynamic topography will profoundly affect our understanding the the relationship between surface geology and deep Earth processes. A major difficulty is the 'tyranny of isostasy'. In other words, dynamic topography is difficult to measure because crustal and lithospheric thickness and density changes are the dominant control of surface elevation. Some progress can be made along continental margins by measuring residual depth anomalies of the oldest oceanic floor on newly available seismic reflection and wide-angle profiles. These estimates of dynamic topography have amplitudes of ±1 km and wavelengths of 102-104 km. They mostly, but not always, correlate with long wavelength free-air gravity anomalies. Correlation with seismic tomographic images is much poorer. The distribution of dynamic topography throughout the rest of the oceanic realm can be supplemented by using ship-track data in regions with sparse sedimentary cover and by exploiting the mid-oceanic ridge system. On the continents, it is more difficult to measure dynamic topography with the same accuracy since the density structure of continental lithosphere is so variable but progress can be made on three fronts. First, long-wavelength gravity anomalies which straddle continental margins are an obvious and important guide. Secondly, stratal geometries across continental shelves contain information about positive and negative surface elevation changes. In several cases, 2- and 3-D seismic surveys calibrated by boreholes can be used to constrain spatial and temporal patterns of dynamic topography. In the North Atlantic Ocean, examples of buried ephemeral landscapes suggest that dynamic topography can grow and decay on timescales as short as a few million years. Recognition of positive and negative vertical motions, which cannot be accounted for by global eustasy, is encouraging and suggests that we are on the verge of creating global dynamic topographic maps which can be used to test predictive global models.

White, Nicky

2013-04-01

7

Static and dynamic support of the Pannonian basin topography  

NASA Astrophysics Data System (ADS)

Determination of isostatic gravity anomalies more than half a century ago indicated that the Pannonian basin was "overcompensated", i. e. it was more elevated than predicted by an Airy-type isostatic compensation model. In other words, the isostatic equilibrium position of this strongly attenuated crust should be well below the sea level. We have revisited this early finding in the possession of reliable data on the structure of the lithosphere-asthenosphere system (Faccenna et al. 2014) and skill to simulate the effect of upper mantle convection on the topography (Becker et al. 2014). The static component of the topography relative to a reference level can be calculated by the assumption that a lithospheric column consisting of a crustal layer and a mantle lid floats freely within the asthenosphere. The difference between the actual and calculated topography in the Pannonian basin turns out to be a robust feature with values as high as 1000 meters This residual topography is supposed to be a dynamic feature and explained in terms of instantaneous mantle flow due to temperature anomalies as inferred from regional P and S wave tomography. Dynamic topography is derived from the radial tractions acting upon a free-slip surface boundary in a Newtonian-type fluid (Becker et al. 2014). Results show a remarkably good fit between dynamic and residual topography pattern suggesting a marked convective support of the elevated Pannonian basin. Finally, we argue that mantle flow pattern in the Pannonian region is part of the Mediterranean upper mantle concvection system, which has been under the control of lithospheric subduction, rollback and eventual slab breakoff processes (Faccenna et al. 2014).

Horváth, Ferenc; Becker, Thorsten; Faccenna, Claudio; Balázs, Attila

2014-05-01

8

Impact of lithosphere rheology on the dynamic topography  

NASA Astrophysics Data System (ADS)

Dynamic topography is a key observable signature of the Earth's and planetary (e.g. Venus) mantle dynamics. In general view, it reflects complex mantle flow patterns, and hence is supposed to correlate at different extent with seismic tomography, SKS fast orientations, geodetic velocity fields and geoid anomalies. However, identification of dynamic topography had no systematic success, specifically in the Earth's continents. Here we argue that lithosphere rheology, in particular, rheological stratification of continents, results in modulation of dynamic topography, converting commonly expected long-wavelength/small amplitude undulations into short-wavelength surface undulations with wide amplitude spectrum, superimposed onto "tectonic" topography. These ideas are explored in 3D using unprecedentedly high resolution numerical experiments (grid step size 2-3 km for 1500x1500x600 km computational area) incorporating realistic rheologically stratified lithosphere. Such high resolution is actually needed to resolve small-scale crustal faulting and inter-layer coupling/uncoupling that shape surface topography. The results reveal strikingly discordant, counterintuitive features of 3D dynamic topography, going far beyond the inferences from previous models. In particular, even weak anisotropic tectonic stress field results both in large-scale small-amplitude dynamic topography and in strongly anisotropic short-wavelength (at least in one direction) dynamic topography with wide amplitude range (from 100 to 2000-3000 m), including basins and ranges and large-scale linear normal and strike-slip faults. Even very slightly pre-stressed strong lithosphere yields and localizes deformation much easier , than un-prestressed one, in response to plume impact and mantle flow. The results shed new light on the importance of lithosphere rheology and active role of lithosphere in mantle-lithosphere interactions as well as on the role of mantle flow and far-field stresses in tectonic-scale deformation. We show, for example, that crustal fault patterns initiated by plume impact are rapidly re-organized in sub-linear rifts and spreading centers, which orientation is largely dictated (e.g., perpendicular to) by the direction of the tectonic far-field stress field, as well as the plume-head material soon starts to flow along the sub-linear rifted shear zones in crustal and mantle lithosphere further amplifying their development. The final surface deformation and mantle flow patterns rapidly loose the initial axisymmetric character and take elongated sub-linear shapes whereas brittle deformation at surface is amplified and stabilized by coherent flow of mantle/plume-head material from below. These "tectonically" looking dynamic topography patterns are quite different from those expected from conventional models as well as from those directly observed, for example, on Venus where plume-lithosphere interactions produce only axisymmetric coronae domal-shaped features with radiating extensional rifts, suggesting that the Venusian lithosphere is rheologically too weak , and its crust is too thin, to produce any significant impact on the dynamic topography.

Burov, Evgueni; Gerya, Taras; Koptev, Alexander

2014-05-01

9

Dynamic wetting and spreading and the role of topography.  

PubMed

The spreading of a droplet of a liquid on a smooth solid surface is often described by the Hoffman-de Gennes law, which relates the edge speed, v(e), to the dynamic and equilibrium contact angles ? and ?(e) through [Formula: see text]. When the liquid wets the surface completely and the equilibrium contact angle vanishes, the edge speed is proportional to the cube of the dynamic contact angle. When the droplets are non-volatile this law gives rise to simple power laws with time for the contact angle and other parameters in both the capillary and gravity dominated regimes. On a textured surface, the equilibrium state of a droplet is strongly modified due to the amplification of the surface chemistry induced tendencies by the topography. The most common example is the conversion of hydrophobicity into superhydrophobicity. However, when the surface chemistry favors partial wetting, topography can result in a droplet spreading completely. A further, frequently overlooked consequence of topography is that the rate at which an out-of-equilibrium droplet spreads should also be modified. In this report, we review ideas related to the idea of topography induced wetting and consider how this may relate to dynamic wetting and the rate of droplet spreading. We consider the effect of the Wenzel and Cassie-Baxter equations on the driving forces and discuss how these may modify power laws for spreading. We relate the ideas to both the hydrodynamic viscous dissipation model and the molecular-kinetic theory of spreading. This suggests roughness and solid surface fraction modified Hoffman-de Gennes laws relating the edge speed to the dynamic and equilibrium contact angle. We also consider the spreading of small droplets and stripes of non-volatile liquids in the capillary regime and large droplets in the gravity regime. In the case of small non-volatile droplets spreading completely, a roughness modified Tanner's law giving the dependence of dynamic contact angle on time is presented. We review existing data for the spreading of small droplets of polydimethylsiloxane oil on surfaces decorated with micro-posts. On these surfaces, the initial droplet spreads with an approximately constant volume and the edge speed-dynamic contact angle relationship follows a power law [Formula: see text]. As the surface texture becomes stronger the exponent goes from p = 3 towards p = 1 in agreement with a Wenzel roughness driven spreading and a roughness modified Hoffman-de Gennes power law. Finally, we suggest that when a droplet spreads to a final partial wetting state on a rough surface, it approaches its Wenzel equilibrium contact angle in an exponential manner with a time constant dependent on roughness. PMID:21715886

McHale, Glen; Newton, Michael I; Shirtcliffe, Neil J

2009-11-18

10

Effects of latent heat release at phase boundaries on flow in the Earth’s mantle, phase boundary topography and dynamic topography at the Earth’s surface  

Microsoft Academic Search

Mantle flow models that do not consider the effects of latent heat on phase boundaries typically predict dynamic surface topography too large to be compatible with observations. Here these effects were implemented in a mantle flow model and resulting changes in dynamic topography and topography of phase boundaries were computed. Inclusion of these effects was found to reduce the rms

Bernhard Steinberger

2007-01-01

11

The dynamics of the Mississippi River plume: Impact of topography, wind and offshore forcing  

E-print Network

The dynamics of the Mississippi River plume: Impact of topography, wind and offshore forcing) were employed to investigate the dynamical processes controlling the fate of the Mississippi River), The dynamics of the Mississippi River plume: Impact of topography, wind and offshore forcing on the fate

Miami, University of

12

Dynamic wetting and spreading and the role of topography  

NASA Astrophysics Data System (ADS)

The spreading of a droplet of a liquid on a smooth solid surface is often described by the Hoffman-de Gennes law, which relates the edge speed, ve, to the dynamic and equilibrium contact angles ? and ?e through v_{\\mathrm {e}} \\propto \\theta (\\theta^{2}-\\theta_{\\mathrm {e}}^{2}) . When the liquid wets the surface completely and the equilibrium contact angle vanishes, the edge speed is proportional to the cube of the dynamic contact angle. When the droplets are non-volatile this law gives rise to simple power laws with time for the contact angle and other parameters in both the capillary and gravity dominated regimes. On a textured surface, the equilibrium state of a droplet is strongly modified due to the amplification of the surface chemistry induced tendencies by the topography. The most common example is the conversion of hydrophobicity into superhydrophobicity. However, when the surface chemistry favors partial wetting, topography can result in a droplet spreading completely. A further, frequently overlooked consequence of topography is that the rate at which an out-of-equilibrium droplet spreads should also be modified. In this report, we review ideas related to the idea of topography induced wetting and consider how this may relate to dynamic wetting and the rate of droplet spreading. We consider the effect of the Wenzel and Cassie-Baxter equations on the driving forces and discuss how these may modify power laws for spreading. We relate the ideas to both the hydrodynamic viscous dissipation model and the molecular-kinetic theory of spreading. This suggests roughness and solid surface fraction modified Hoffman-de Gennes laws relating the edge speed to the dynamic and equilibrium contact angle. We also consider the spreading of small droplets and stripes of non-volatile liquids in the capillary regime and large droplets in the gravity regime. In the case of small non-volatile droplets spreading completely, a roughness modified Tanner's law giving the dependence of dynamic contact angle on time is presented. We review existing data for the spreading of small droplets of polydimethylsiloxane oil on surfaces decorated with micro-posts. On these surfaces, the initial droplet spreads with an approximately constant volume and the edge speed-dynamic contact angle relationship follows a power law v_{\\mathrm {e}} \\propto \\theta ^p . As the surface texture becomes stronger the exponent goes from p = 3 towards p = 1 in agreement with a Wenzel roughness driven spreading and a roughness modified Hoffman-de Gennes power law. Finally, we suggest that when a droplet spreads to a final partial wetting state on a rough surface, it approaches its Wenzel equilibrium contact angle in an exponential manner with a time constant dependent on roughness.

McHale, Glen; Newton, Michael I.; Shirtcliffe, Neil J.

2009-11-01

13

Modeling the dynamic component of the geoid and topography of Venus  

E-print Network

Modeling the dynamic component of the geoid and topography of Venus M. Pauer,1,2 K. Fleming,3 and O) the density structure of Venus' mantle can be approximated by a model in which the mass anomaly distribution of the geoid and topography of Venus, J. Geophys. Res., 111, E11012, doi:10.1029/2005JE002511. 1. Introduction

Cerveny, Vlastislav

14

Global dynamic topography at very-high resolution for Geohazards, Climate Change and Vulnerability mapping  

E-print Network

the mission life-time > Monitor seasonnal 3D topography dynamics > Instrument · Combination of active the time, nor everywhere · Optical system impeded by clouds ­ Orbits minimize cloud potential (local time

Berthier, Etienne

15

A Tailored Computation of the Mean Dynamic Topography for a Consistent Integration into Ocean Circulation Models  

NASA Astrophysics Data System (ADS)

Geostrophic surface velocities can be derived from the gradients of the mean dynamic topography—the difference between the mean sea surface and the geoid. Therefore, independently observed mean dynamic topography data are valuable input parameters and constraints for ocean circulation models. For a successful fit to observational dynamic topography data, not only the mean dynamic topography on the particular ocean model grid is required, but also information about its inverse covariance matrix. The calculation of the mean dynamic topography from satellite-based gravity field models and altimetric sea surface height measurements, however, is not straightforward. For this purpose, we previously developed an integrated approach to combining these two different observation groups in a consistent way without using the common filter approaches (Becker et al. in J Geodyn 59(60):99-110, 2012; Becker in Konsistente Kombination von Schwerefeld, Altimetrie und hydrographischen Daten zur Modellierung der dynamischen Ozeantopographie 2012). Within this combination method, the full spectral range of the observations is considered. Further, it allows the direct determination of the normal equations (i.e., the inverse of the error covariance matrix) of the mean dynamic topography on arbitrary grids, which is one of the requirements for ocean data assimilation. In this paper, we report progress through selection and improved processing of altimetric data sets. We focus on the preprocessing steps of along-track altimetry data from Jason-1 and Envisat to obtain a mean sea surface profile. During this procedure, a rigorous variance propagation is accomplished, so that, for the first time, the full covariance matrix of the mean sea surface is available. The combination of the mean profile and a combined GRACE/GOCE gravity field model yields a mean dynamic topography model for the North Atlantic Ocean that is characterized by a defined set of assumptions. We show that including the geodetically derived mean dynamic topography with the full error structure in a 3D stationary inverse ocean model improves modeled oceanographic features over previous estimates.

Becker, S.; Losch, M.; Brockmann, J. M.; Freiwald, G.; Schuh, W.-D.

2014-11-01

16

Measurement of fine dynamic changes of corneal topography by use of interferometry  

NASA Astrophysics Data System (ADS)

Paper presents results of in vivo measurements of dynamic variations of the corneal topography by use of the Twyman Green interferometer. Sequence of interferograms were recorded by the CCD camera and stored in the computer memory. Then the fringe tracking method was used separately to each interferogram giving the phase surface of the wave reflected from the cornea in the numerical form. Results from neighboring interferograms were subtracted giving new sequence of changes of the corneal topography within 40 ms. Obtained results show the complex space distribution of the corneal topography variations.

Kasprzak, Henryk T.; Jaronski, Jaroslaw W.

2002-06-01

17

Study of the tear topography dynamics using a lateral shearing interferometer  

NASA Astrophysics Data System (ADS)

The dynamics of the pre-corneal tear film topography are studied on 21 subjects with a purpose-built lateral shearing interferometer. Interesting tear topography features such as post-blink undulation, break-up, eyelid-produced bumps/ridges, bubbles and rough pre-contact lens tear surfaces were recorded. Using the calculated tear topography maps, the effects of the tear dynamics in visual performance, refractive surgery and ophthalmic adaptive optics are discussed in terms of wavefront RMS. The potential of lateral shearing interferometry for clinical applications such as dry eye diagnosis and contact lens performance studies is illustrated by the recorded topography features such as post-blink undulation, break-up, eyelid-produced bumps/ridges, bubbles and rough tear surfaces in front of contact lenses.

Dubra, Alfredo; Paterson, Carl; Dainty, Christopher

2004-12-01

18

Mesozoic ocean basins and the link to modeled dynamic topography of the circum-Arctic  

NASA Astrophysics Data System (ADS)

The tectonic evolution of the circum-Arctic is complex, punctuated by the opening and closing of several ocean basins, and the accretion and deformation of numerous autochthonous and allochthonous terranes. Here, we present a new plate tectonic reconstruction for the circum-Arctic and adjacent regions since the start of the Jurassic, incorporating the opening of the Amerasia Basin and associated closure of the South Anuyi Ocean. The location of palaeo-subduction zones can be used to infer mantle heterogeneity structure beneath north-eastern North America, the Canadian Arctic Islands, Northern Atlantic and Russia. We use this kinematic plate reconstruction to drive forward geodynamic models of mantle flow from which we compute the spatio-temporal evolution of dynamic topography. The passage of the evolving circum-Arctic over subducting slabs is expected to impart long-wavelength subsidence followed by uplift. Separating the isostatic and dynamic contributions to circum-Arctic topography is challenging because of the paucity of offshore and onshore regional datasets, and is complicated by multiple processes, including rifting, long-wavelength mantle flow, magmatic underplating, sediment loading, and volcanism. Therefore, we focus on the possible correlation between the evolution of long-wavelength topography and post-Jurassic subduction zones. We compare the dynamic topography predicted by our geodynamic models to residual topography, published palaeo-geographic maps and anomalous tectonic subsidence.

Shephard, Grace; Flament, Nicolas; Heine, Christian; Dietmar Müller, R.

2013-04-01

19

The Mid-Pliocene sea-level conundrum: Glacial isostasy, eustasy and dynamic topography  

NASA Astrophysics Data System (ADS)

Determining eustatic sea level during the Mid-Pliocene warm period (?3.3 to 2.9 Ma) has been a central but elusive goal in the study of past warm climates. Estimates of eustatic sea level based on geologic data span a broad range; variation that we now recognize is due in part to geographically varying post-depositional displacement caused by glacial isostatic adjustment and dynamic topography. In this study, we combine field observations and glacial isostatic adjustment modeling to estimate the dynamic topography signal in three areas that are important to paleo-sea level studies of the Mid-Pliocene warm period (South Africa, West Australia and southeastern United States). We show that dynamic topography played a significant role in the post-depositional displacement of Pliocene, and even younger Pleistocene, shorelines. In this regard, we provide a robust paleo-sea level elevation data set, corrected for glacial isostatic adjustment, that can be used to evaluate predictions from mantle flow models of dynamic topography.

Rovere, A.; Raymo, M. E.; Mitrovica, J. X.; Hearty, P. J.; O'Leary, M. J.; Inglis, J. D.

2014-02-01

20

Bioinspired surfaces with dynamic topography for active control of biofouling.  

PubMed

Dynamic change of the surface area and topology of elastomers is used as a general, environmentally friendly approach for effectively detaching micro- and macro-fouling organisms adhered on the elastomer surfaces. Deformation of elastomer surfaces under electrical or pneumatic actuation can debond various biofilms and barnacles. The bio-inspired dynamic surfaces can be fabricated over large areas through simple and practical processes. This new mechanism is complementary with existing materials and methods for biofouling control. PMID:23292960

Shivapooja, Phanindhar; Wang, Qiming; Orihuela, Beatriz; Rittschof, Daniel; López, Gabriel P; Zhao, Xuanhe

2013-03-13

21

Exploiting Oceanic Residual Depth to Quantify Present-day Dynamic Topography at the Earth's Surface  

NASA Astrophysics Data System (ADS)

Convective circulation within the mantle causes vertical motions at the Earth's surface. This dynamic topography is time dependent and occurs on wavelengths of 1000s km with maximum amplitudes of ±2 km. Convective simulation models have been used extensively to make predictions of dynamic topography and have thus far out-paced observational constraints. Here, the well-established relationship between seafloor subsidence and age is used to produce a global map of residual depth anomalies in the oceanic realm. Care is taken to remove other causes of topography, including an isostatic correction for sedimentary loading that takes compaction into account, a correction for variable oceanic crustal thickness, and lithospheric thickening with age away from mid-ocean ridge spreading centres. A dataset including over 1000 seismic reflection profiles and 300 modern wide-angle refraction experiments has been amassed, primarily on old ocean floor adjacent to the continents. Calculation of residual depth yields a map of present-day dynamic topography with amplitudes significantly larger than the errors associated with the corrections. One of the most interesting results occurs along the west coast of Africa, where two full 2000 km wavelengths of dynamic topography have been captured with amplitudes ±1 km that correlate well with the long-wavelength free air gravity anomaly. Comparison with predictive models reveal poor to moderate correlations. This is a direct result of the limited resolution of the mantle tomography models used to set-up convection simulations and also the currently poor understanding of viscosity structure within the Earth. It is hoped that this residual depth dataset should provide an excellent surface boundary constraint for future convective simulation.

Hoggard, Mark; White, Nicky

2014-05-01

22

Dynamic topography change of the eastern United States since 3 million years ago.  

PubMed

Sedimentary rocks from Virginia through Florida record marine flooding during the mid-Pliocene. Several wave-cut scarps that at the time of deposition would have been horizontal are now draped over a warped surface with a maximum variation of 60 meters. We modeled dynamic topography by using mantle convection simulations that predict the amplitude and broad spatial distribution of this distortion. The results imply that dynamic topography and, to a lesser extent, glacial isostatic adjustment account for the current architecture of the coastal plain and proximal shelf. This confounds attempts to use regional stratigraphic relations as references for longer-term sea-level determinations. Inferences of Pliocene global sea-level heights or stability of Antarctic ice sheets therefore cannot be deciphered in the absence of an appropriate mantle dynamic reference frame. PMID:23686342

Rowley, David B; Forte, Alessandro M; Moucha, Robert; Mitrovica, Jerry X; Simmons, Nathan A; Grand, Stephen P

2013-06-28

23

Free volume hypothetical scanning molecular dynamics method for the absolute free energy of liquids  

E-print Network

Free volume hypothetical scanning molecular dynamics method for the absolute free energy of liquids for calculating the absolute entropy, S, and free energy, F, by analyzing Boltzmann samples obtained by Monte. In this paper we remove the excluded volume EV restriction, replacing it by a "free volume" FV approach

Meirovitch, Hagai

24

The bottom topography and dynamics of the Obskaya and Baydaratskaya Bays, Kara Sea  

NASA Astrophysics Data System (ADS)

The development of the arctic gas fields requires a gas transport system to be laid across the Obskaya Bay and the Baydaratskaya Bay, Kara Sea. Designing, construction and safe operation of the offshore parts of the crossing demands special knowledge about a structure of the bottom topography and coastal zone dynamics. Results of investigation indicate a difference between those regions and common features of structure and evolution. Owing to a quite large scale of research it was possible to detail the bottom topography, to reveal separate elements and forms. The analyses of topography were executed to define the mechanisms and basic phases of relief formation. Accordingly, the geomorphological map describing the bottom topography by the set of parameters (major of them are morphology, morphometry, age, genesis and dynamics) has also become more detailed. Geomorphological structure of a seabed is the important source of the information on location of permafrost relicts, sites of concentration of rip currents, intensive ice bottom gouging, deformations of an underwater coastal slope and other adverse phenomena and dangerous exogenous processes. The analysis of all these data allowed making prediction of bottom topography development, to plan and carry out an engineering construction. Digital model of bottom topography is a basis for engineering constructions designing. Creation of digital models of bottom topography was carried out by the original method consisted of several stages and based on manual author's processing and interpretation of maps. Also a large amount of archival and literary materials on geophysics, geology, geomorphology and paleogeography has been involved for digital model creation with the purpose to determine the features of morphostructure and genesis of the basic elements. It is established, that the geomorphological structure of the bottom of the Baydaratskaya and Obskaya Bays reflects consecutive change of the conditions and relief formation processes in Late Pleistocene-Holocene, since a continental stage of development of the drained erosion plain down to present time, including attributes of non-uniform rise of a sea level and activity of coastal processes (underwater bluffs, ancient beach ridges et al.).

Ermolov, A.; Noskov, A.; Ogorodov, S.

2009-04-01

25

Absolute Binding Free Energy Calculations Using Molecular Dynamics Simulations with Restraining Potentials  

Microsoft Academic Search

The absolute (standard) binding free energy of eight FK506-related ligands to FKBP12 is calculated using free energy perturbation molecular dynamics (FEP\\/MD) simulations with explicit solvent. A number of features are implemented to improve the accuracy and enhance the convergence of the calculations. First, the absolute binding free energy is decomposed into sequential steps during which the ligand-surrounding interactions as well

Jiyao Wang; Yuqing Deng; Benoît Roux

2006-01-01

26

Flight dynamics facility operational orbit determination support for the ocean topography experiment  

NASA Technical Reports Server (NTRS)

The Ocean Topography Experiment (TOPEX/POSEIDON) mission is designed to determine the topography of the Earth's sea surface across a 3 yr period, beginning with launch in June 1992. The Goddard Space Flight Center Dynamics Facility has the capability to operationally receive and process Tracking and Data Relay Satellite System (TDRSS) tracking data. Because these data will be used to support orbit determination (OD) aspects of the TOPEX mission, the Dynamics Facility was designated to perform TOPEX operational OD. The scientific data require stringent OD accuracy in navigating the TOPEX spacecraft. The OD accuracy requirements fall into two categories: (1) on orbit free flight; and (2) maneuver. The maneuver OD accuracy requirements are of two types; premaneuver planning and postmaneuver evaluation. Analysis using the Orbit Determination Error Analysis System (ODEAS) covariance software has shown that, during the first postlaunch mission phase of the TOPEX mission, some postmaneuver evaluation OD accuracy requirements cannot be met. ODEAS results also show that the most difficult requirements to meet are those that determine the change in the components of velocity for postmaneuver evaluation.

Bolvin, D. T.; Schanzle, A. F.; Samii, M. V.; Doll, C. E.

1991-01-01

27

Interferometer for measuring the dynamic surface topography of a human tear film  

NASA Astrophysics Data System (ADS)

The anterior refracting surface of the eye is the thin tear film that forms on the surface of the cornea. Following a blink, the tear film quickly smoothes and starts to become irregular after 10 seconds. This irregularity can affect comfort and vision quality. An in vivo method of characterizing dynamic tear films has been designed based upon a near-infrared phase-shifting interferometer. This interferometer continuously measures light reflected from the tear film, allowing sub-micron analysis of the dynamic surface topography. Movies showing the tear film behavior can be generated along with quantitative metrics describing changes in the tear film surface. This tear film measurement allows analysis beyond capabilities of typical fluorescein visual inspection or corneal topography and provides better sensitivity and resolution than shearing interferometry methods. The interferometer design is capable of identifying features in the tear film much less than a micron in height with a spatial resolution of about ten microns over a 6 mm diameter. This paper presents the design of the tear film interferometer along with the considerations that must be taken when designing an interferometer for on-eye diagnostics. Discussions include eye movement, design of null optics for a range of ocular geometries, and laser emission limits for on-eye interferometry.

Primeau, Brian C.; Greivenkamp, John E.

2012-03-01

28

The Time Dependance of Dynamic Topography: Mantle Dynamic Contributions to Local and Global Sea-Level Histories  

NASA Astrophysics Data System (ADS)

Earth's topography plays an important role in many surface processes, particularly through its influence on the water cycle and erosional processes. Our ability to predict weather patterns and surface/subsurface hydrological processes depends upon our knowledge of this field. Similarly, understanding the evolution of topography through time (paleo-topography) is critically important for the accurate modeling of past climate states such as that of the last glacial maximum. Whilst the present day topographic field can be accurately inferred over the entire globe using satellite based sensors and geodetic techniques, no equivalently comprehensive tools exist that enable access to paleo-topography. The rock record allows for limited, local estimations of deposition elevation with respect to sea level using appropriate fossils combined with sedimentological analyses. However, this method is not available in most locations as a consequence of poor-preservation of the requisite sea level indicators and in any event the accuracy of the relative sea level record is often compromised. Furthermore, just as topography itself consists of distinct dynamic and isostatic contributions, relatives sea level also consists of two contributions, respectively that due to the vertical motion of the surface of the solid Earth and that due to the changing volume of water in the global oceans. In this paper we study the time dependence of Earth's dynamic topography that has occurred over the recent past due to the action of the mantle convection process. We use a modern model of mantle mixing, an extension to three dimensions of the recently published control volume based convection model of Shahnas and Peltier (2010, JGR, vol 115, B11408). This is initialized using a mantle temperature field inferred on the basis of modern seismic tomographic imaging analysis, which enables the model to simulate the present day dynamical state of Earth's mantle. The use of this methodology enables the model to be employed to study the present state of the mantle and its evolution in the recent geological past. The predictions of the model that interest us are those of the rate of uplift and depression of the crust that contribute to records of relative sea level history over timescales sufficiently long to encompass several Late Quaternary glacial cycles. We employ a number of available local records of the time dependence of dynamical topography such as the coral based Barbados record of Peltier and Fairbanks (2006, QSR 25, pp. 3322-3337) to first demonstrate the accuracy with which the convection model is able to reconcile such observational constraints. Although several of the best available constraint data sets derive from regions in the near vicinity of active subduction zones, we proceed to apply the model's predictions to a number of (assumed to be) passive continental margins from which data have been derived that have been assumed to represent variations in eustatic sea level due to the variation of continental land ice volume such as those recently discussed by Miller et al. (2012, Geology 20, pp. 407-410). We assess the extent to which the passive continental margin assumption may have led to significant errors in the inference of global sea level rise for the mid-Pliocene interval of time centered upon 3 Ma.

Durbin, C. J.; Shahnas, M.; Peltier, W. R.

2012-12-01

29

How well can we measure the ocean's mean dynamic topography from space?  

NASA Astrophysics Data System (ADS)

gravity missions have produced a dramatic improvement in our ability to measure the ocean's mean dynamic topography (MDT) from space. To fully exploit this oceanic observation, however, we must quantify its error. To establish a baseline, we first assess the error budget for an MDT calculated using a 3rd generation GOCE geoid and the CLS01 mean sea surface (MSS). With these products, we can resolve MDT spatial scales down to 250 km with an accuracy of 1.7 cm, with the MSS and geoid making similar contributions to the total error. For spatial scales within the range 133-250 km the error is 3.0 cm, with the geoid making the greatest contribution. For the smallest resolvable spatial scales (80-133 km) the total error is 16.4 cm, with geoid error accounting for almost all of this. Relative to this baseline, the most recent versions of the geoid and MSS fields reduce the long and short-wavelength errors by 0.9 and 3.2 cm, respectively, but they have little impact in the medium-wavelength band. The newer MSS is responsible for most of the long-wavelength improvement, while for the short-wavelength component it is the geoid. We find that while the formal geoid errors have reasonable global mean values they fail capture the regional variations in error magnitude, which depend on the steepness of the sea floor topography.

Bingham, R. J.; Haines, K.; Lea, D. J.

2014-06-01

30

Anomalous Subsidence at Rifted Continental Margins: Distinguishing Mantle Dynamic Topography from Anomalous Oceanic Crustal Thickness  

NASA Astrophysics Data System (ADS)

It has been proposed that some continental rifted margins have anomalous subsidence histories and that at breakup they were elevated at shallower bathymetries than the isostatic response of classical rift models (McKenzie 1978) would predict. The existence of anomalous syn or post breakup subsidence of this form would have important implications for our understanding of the geodynamics of continental breakup and rifted continental margin formation, margin subsidence history and the evolution of syn and post breakup depositional systems. We have investigated three rifted continental margins; the Gulf of Aden, Galicia Bank and the Gulf of Lions, to determine whether the oceanic crust in the ocean-continent transition of these margins has present day anomalous subsidence and if so, whether it is caused by mantle dynamic topography or anomalous oceanic crustal thickness. Residual depth anomalies (RDA) corrected for sediment loading, using flexural backstripping and decompaction, have been calculated by comparing observed and age predicted oceanic bathymetries in order to identify anomalous oceanic bathymetry and subsidence at these margins. Age predicted bathymetric anomalies have been calculated using the thermal plate model predictions from Crosby & McKenzie (2009). Non-zero sediment corrected RDAs may result from anomalous oceanic crustal thickness with respect to the global average, or from mantle dynamic uplift. Positive RDAs may result from thicker than average oceanic crust or mantle dynamic uplift; negative RDAs may result from thinner than average oceanic crust or mantle dynamic subsidence. Gravity inversion incorporating a lithosphere thermal gravity anomaly correction and sediment thickness from 2D seismic data has been used to determine Moho depth and oceanic crustal basement thickness. The reference Moho depths used in the gravity inversion have been calibrated against seismic refraction Moho depths. The gravity inversion crustal basement thicknesses together with Airy isostasy have been used to predict a "synthetic" gravity derived RDA. Sediment corrected RDA for oceanic crust in the Gulf of Aden are positive (+750m) indicating anomalous uplift with respect to normal subsidence. Gravity inversion predicts normal thickness oceanic crust and a zero "synthetic" gravity derived RDA in the oceanic domain. The difference between the positive sediment corrected RDA and the zero "synthetic" gravity derived RDA, implies that the anomalous subsidence reported in the Gulf of Aden is the result of mantle dynamic uplift. For the oceanic crust outboard of Galicia Bank both the sediment corrected RDA and the "synthetic" gravity derived RDA are negative (-800m) and of similar magnitude, indicating anomalous subsidence, which is the result of anomalously thin oceanic crust, not mantle dynamic topography. We conclude that there is negligible mantle dynamic topography influencing the Galicia Bank region. In the Gulf of Lions, gravity inversion predicts thinner than average oceanic crust. Both sediment corrected RDA (-1km) and "synthetic" gravity derived RDA (-500m) are negative. The more negative sediment corrected RDA compared with the "synthetic" gravity derived RDA implies that the anomalous subsidence in the Gulf of Lions is the result of mantle dynamic subsidence as well as thinner than average oceanic crust.

Cowie, L.; Kusznir, N. J.

2012-12-01

31

Mean dynamic topography estimates purely based on GOCE gravity field models and altimetry  

NASA Astrophysics Data System (ADS)

The quality of mean dynamic topography (MDT) models derived from an altimetric mean sea surface and a gravity field model mainly depends on the spatial resolution and accuracy of the particular gravity field model. We use an integrated approach which allows for estimating the MDT and its (inverse) covariance matrix on a predefined grid which is one of the requirements for ocean data assimilation. The quality and accuracy of the MDT directly reflects the quality and accuracy of the used gravity field model. For the first time, MDT estimates along with its full error covariance matrix based on Gravity Field and Steady-State Ocean Circulation Explorer (GOCE) data can be provided. We demonstrate the progress accomplished with GOCE processing and the valuable contribution of the GOCE gravity field models regarding the estimation of the MDT by showing results based on altimetric observations of Jason-1 and Envisat in combination with different GOCE gravity field models for the North Atlantic.

Becker, S.; Brockmann, J. M.; Schuh, W.-D.

2014-03-01

32

Advances in large-scale ocean dynamics from a decade of satellite altimetric measurement of ocean surface topography  

NASA Technical Reports Server (NTRS)

The past decade has seen the most intensive observations of the global ocean surface topography from satellite altimeters. The Joint U.S./France TOPEX/Poseidon (T/P) Mission has become the longest radar mission ever flown in space, providing the most accurate measurements for the study of ocean dynamics since October 1992.

Fu, L. L.; Menard, Y.

2002-01-01

33

The Effect of Surface Topography on the Nonlinear Dynamics of Rossby Waves  

NASA Technical Reports Server (NTRS)

Boussinesq convection in rotating systems attracts a sustained attention of the fluid dynamics community, because it has intricate non-linear dynamics (Cross & Hohenberg 1993) and plays an important role in geophysical and astrophysical applications, such as the motion of the liquid outer core of Earth, the Red Spot in Jupiter, the giant cells in the Sun etc. (Alridge et al. 1990). A fundamental distinction between the real geo- and astrophysical problems and the idealized laboratory studies is that natural systems are inhomogeneous (Alridge et al. 1990). Heterogeneities modulate the flow and influence significantly the dynamics of convective patterns (Alridge et al. 1990; Hide 1971). The effect of modulations on pattern formation and transition to turbulence in Boussinesq convection is far from being completely understood (Cross & Hohenberg 1993; Aranson & Kramer 2002). It is generally accepted that in the liquid outer core of the Earth the transport of the angular momentum and internal heat occurs via thermal Rossby waves (Zhang et al. 2001; Kuang & Bloxham 1999). These waves been visualized in laboratory experiments in rotating liquid-filled spheres and concentric spherical shells (Zhang et al. 2001; Kuang & Bloxham 1999). The basic dynamical features of Rossby waves have been reproduced in a cylindrical annulus, a system much simpler than the spherical ones (Busse & Or 1986; Or & Busse 1987). For convection in a cylindrical annulus, the fluid motion is two-dimensional, and gravity is replaced by a centrifugal force, (Busse & Or 1986; Or & Busse 1987). Hide (1971) has suggested that the momentum and heat transport in the core might be influenced significantly by so-called bumps, which are heterogeneities on the mantle-core boundary. To model the effect of surface topography on the transport of momentum and energy in the liquid outer core of the Earth, Bell & Soward (1996), Herrmann & Busse (1998) and Westerburg & Busse (2001) have studied the nonlinear dynamics of thermal Rossby waves in a cylindrical annulus with azimuthally modulated height.

Abarzhi, S. I.; Desjardins, O.; Pitsch, H.

2003-01-01

34

Calibration-free quantification of absolute oxygen saturation based on the dynamics of photoacoustic signals.  

PubMed

Photoacoustic tomography (PAT) is a hybrid imaging technique that has broad preclinical and clinical applications. Based on the photoacoustic effect, PAT directly measures specific optical absorption, which is the product of the tissue-intrinsic optical absorption coefficient and the local optical fluence. Therefore, quantitative PAT, such as absolute oxygen saturation (sO?) quantification, requires knowledge of the local optical fluence, which can only be estimated through invasive measurements or sophisticated modeling of light transportation. In this Letter, we circumvent this requirement by taking advantage of the dynamics in sO?. The new method works when the sO? transition can be simultaneously monitored with multiple wavelengths. For each wavelength, the ratio of photoacoustic amplitudes measured at different sO? states is utilized. Using the ratio cancels the contribution from optical fluence and allows calibration-free quantification of absolute sO?. The new method was validated through both phantom and in vivo experiments. PMID:23903146

Xia, Jun; Danielli, Amos; Liu, Yan; Wang, Lidai; Maslov, Konstantin; Wang, Lihong V

2013-08-01

35

Solid state interferometric interrogator and multiplexer for high-speed dynamic and absolute FBG wavelength measurement  

NASA Astrophysics Data System (ADS)

We present a solid-state FBG array interrogator and multiplexer capable of determining absolute FBG wavelengths and of providing high-speed, high-resolution static and dynamic measurements. Using a described procedure, deployable on multiplexing passive-interferometric schemes, the system is able to determine initial sensor wavelengths and thereafter track wavelength changes with interferometric resolution. The scheme allows high-resolution interrogation of FBG sensor arrays to be applied to many industrial applications, where previously the lack of combined absolute and quasistatic wavelength measurement precluded the use of interferometric techniques. Using a preliminary laboratory embodiment, we demonstrate a wavelength determination accuracy of <0.3 nm and a measurement resolution of 10 fm/?Hz, and propose pathways to improved performance and miniaturisation.

Orr, Philip; Perry, Marcus; Fusiek, Grzegorz; Niewczas, Pawe?

2013-05-01

36

Impacts of topography on aspen and black spruce successional dynamics in the boreal forest  

NASA Astrophysics Data System (ADS)

The boreal forest contains over 30 percent of Earth's terrestrial carbon, stored mainly as organic matter in soils underlain by discontinuous permafrost. In interior Alaska, black spruce trees dominate these nutrient-depleted soils where the combination of cold temperatures and nutrient-poor black spruce detritus results in an accumulation of a thick layer of organic matter that is not easily decomposed. However, warming temperatures have decreased fire return intervals and resulted in permafrost recession, opening more boreal forest space to early-successional hardwoods such aspen. Because aspen and black spruce stands have a much different capacity for near-surface carbon storage, shifts in vegetation type have important implications for carbon storage in boreal forests. Yet, existing global climate models that run at resolutions of 50-100 square kilometers cannot capture vegetation dynamics that result from fire and topographic variation, where significant heterogeneity is present on scales of 1 square kilometer or less. In this study we use the Ecosystem Demography model version 2 to examine the growth and mortality dynamics of black spruce and aspen trees. Employing meteorological forcing data from the Bonanza Creek Long Term Ecological Research (BNZ-LTER) weather station (64.70°N, 148.25°W) we investigate the interdependence of permafrost depth, soil temperature, soil moisture content and plant functional type on topography. Modeled plant densities are corroborated with observed aspen and black spruce distributions at the BNZ-LTER and nearby Delta Junction, AK. We then show how an accurate spatial parameterization of aspen and black spruce trees can be used to better simulate boreal zone carbon dynamics with receding permafrost and increased fire frequency.

Trugman, A. T.; Medvigy, D.

2013-12-01

37

Dynamic sea surface topography, gravity, and improved orbit accuracies from the direct evaluation of Seasat altimeter data  

NASA Technical Reports Server (NTRS)

A gravitational model incorporating Seasat altimetry, surface gravimetry, and satellite tracking data has been determined in terms of global spherical harmonics complete to degree and order 50. This model, PGS-3337, uses altimeter data as a dynamic observation of the satellite's height above the sea surface. A solution for the ocean's dynamic topography is recovered simultaneously with the orbit parameters, gravity, and ocean tidal terms. The recovered dynamic topography reveals the global long wavelength circulation of the oceans with a resolution of 2000 km and is very similar to the mean upper ocean dynamic height derived from historical ship observations. The PGS-3337 geoid has an uncertainty of 60 cm rms globally but 25 cm rms over the ocean because of the altimeter measurements. Seasat orbits determined in this solution have an estimated accuracy for the radial position of 20 cm rms. The difference between the altimeter observed sea height and the geoid plus dynamic topography model is 30 cm rms. Contained in these residuals are the sea height variability, as well as errors from the geoid, orbits, tidal models, and altimeter range measurement. This performance level is 2 to 3 times better than that achieved with previous Goddard gravitational models.

Marsh, J. G.; Koblinsky, C. J.; Lerch, F.; Klosko, S. M.; Robbins, J. W.

1990-01-01

38

A new filter for the Mean Dynamic Topography of the ocean derived directly from satellite observations  

NASA Astrophysics Data System (ADS)

The Mean Dynamic Topography (MDT) of the ocean provides valuable information about the ocean's surface currents. Therefore the MDT is computed from satellite observations and then assimilated into ocean models in order to improve the ocean circulation estimates. However, the computation of the MDT from satellite observations of sea surface height and the Earth's gravity field is not straightforward and requires additional filtering of the data combination. The choice of the filter is crucial as it determines the amount of small-scale noise in the data and the resolution of the final MDT. There exist various approaches for the determination of an "optimal" filter. However, they all have in common the more or less subjective choice of the filter type and filter width. Here, a new filter is presented that is determined directly from the geodetic normal equations. By its construction, this filter accurately accounts for the correlations within the MDT data and requires no subjective choice about the filter radius. The new filtered MDT is assimilated into an inverse ocean model. Modifications in the meridional overturning circulation and in the poleward heat transports can be observed, compared to the result of the assimilation using the unfiltered MDT.

Freiwald, G.

2013-12-01

39

New clinical instrument for the early detection of cataract using dynamic light scattering and corneal topography  

NASA Astrophysics Data System (ADS)

A growing cataract can be detected at the molecular level using the technique of dynamic light scattering (DLS). However, the success of this method in clinical use depends upon the precise control of the scattering volume inside a patient's eye and especially during patient's repeat visits. This is important because the scattering volume (cross-over region between the scattered light and incident light) inside the eye in a high-quality DLS set-up is very small (few microns in dimension). This precise control holds the key for success in the longitudinal studies of cataract and during anti-cataract drug screening. We have circumvented these problems by fabricating a new DLS fiber optic probe with a working distance of 40 mm and by mounting it inside a cone of a corneal analyzer. This analyzer is frequently used in mapping the corneal topography during PRK (photorefractive keratectomy) and LASIK (laser in situ keratomileusis) procedures in shaping of the cornea to correct myopia. This new instrument and some preliminary clinical tests on one of us (RRA) showing the data reproducibility are described.

Ansari, Rafat R.; Datiles, Manuel B., III; King, James F.

2000-06-01

40

Exploring effects of lateral viscosity variations on the geoid undulation and dynamic topography at different wavelengths  

NASA Astrophysics Data System (ADS)

The impact of lateral viscosity variations on surface observations are investigated with an Instantaneous three-dimensional spherical shell mantle flow model. A combined density model of seismic tomography and subducting slab models is considered. In addition, a global strain-rate model is used to describe LVVs in the lithosphere. The LVVs in the upper mantle are obtained either by slab or seismic tomography models and the lower mantle LVVs are derived using a relation between seismic velocity and temperature. Effects on the geoid and dynamic topography caused by different wavelengths of LVV in the lithosphere, upper mantle and lower mantle are systematically addressed. The longest-wavelengths (degree 2 and 3) of the geoid anomalies are controlled by the viscosity contrast between the upper and lower mantle. The presence of LVV in the lower mantle guarantees geoid amplitudes to be comparable with the observations, both for long and short wavelengths. The LVVs in the lithosphere and upper mantle have a minor effect on the global pattern of the geoid. However, on the regional scale, a model with LVV gives a better fit to the observed geoid.

Shahraki, M.; Schmeling, H.; Yoshida, M.; Wallner, H.

2012-12-01

41

LES of atmospheric boundary layer flow over fluvial-like anisotropic topography with a dynamic surface drag model  

NASA Astrophysics Data System (ADS)

A dynamic surface drag model (A. & M. 2011, JFM 679, 288 - 314) is applied in LES of atmospheric boundary layer (ABL) flow over fractal-like topography where the height field exhibits power-law energy spectrum. Initially, the dynamic drag model was applied in LES of ABL flow over isotropic synthetic fractal-like roughness. Here we consider fluvial-like anisotropic landscapes. Two main cases are considered. The first is a fluvial-like topography built through numerical solution of the Kardar-Parisi-Zhang equation.ootnotetextThanks also to Profs. P. Passalacqua and F. Porte-Agel for providing KPZ solution fields. The second is a rescaled topography (Texas) map from the U.S. National Elevation Dataset. These landscapes are dominated by anisotropic modes that have emerged through geomorphological erosion processes. The dynamic model yields stable solutions even in these highly anisotropic cases: performance is strongest for cases where the LES grid- and test-filter width are within the landscape ``self-similar'' range. Weaknesses are reported for cases where spectral exponent changes with wavenumber, motivating the development of a scale-dependent version of the dynamic approach using two test-filters.

Anderson, William; Meneveau, Charles

2011-11-01

42

Retrodicting the Cenozoic evolution of the mantle: Implications for dynamic surface topography  

NASA Astrophysics Data System (ADS)

Seismic tomography is the essential starting ingredient for constructing realistic models of the mantle convective flow and for successfully predicting a wide range of convection-related surface observables. However, the lack of knowledge of the initial thermal state of the mantle in the geological past is still an outstanding problem in mantle convection. The resolution of this problem requires models of 3-D mantle evolution that yield maximum consistency with a wide suite of geophysical constraints. Quantifying the robustness of the reconstructed thermal evolution is another major concern. We have carried out mantle dynamic simulations (Glišovi? & Forte, EPSL 2014) using a pseudo-spectral solution for compressible-flow thermal convection in 3-D spectral geometry that directly incorporate: 1) joint seismic-geodynamic inversions of mantle density structure with constraints provided by mineral physics data (Simmons et al., GJI 2009); and 2) constraints on mantle viscosity inferred by inversion of a suite of convection-related and glacial isostatic adjustment data sets (Mitrovica & Forte, EPSL 2004) characterised by Earth-like Rayleigh numbers. These time-reversed convection simulations reveal how the buoyancy associated with hot, active upwellings is a major driver of the mantle-wide convective circulation and the changes in dynamic topography at the Earth's surface. These simulations reveal, for example, a stable and long-lived superplume under the East Pacific Rise (centred under the Easter and Pitcairn hotspots) that was previously identified by Rowley et al. (AGU 2011, Nature in review) on the basis of plate kinematic data. We also present 65 Myr reconstructions of the Reunion plume that gave rise to the Deccan Traps.

Glišovi?, Petar; Forte, Alessandro; Rowley, David; Simmons, Nathan; Grand, Stephen

2014-05-01

43

Dynamic changes in corneal topography and its influence on the point-spread function of the eye  

NASA Astrophysics Data System (ADS)

The dynamic changes of the anterior surface of the eye are investigated. A Twyman-Green interferometer is used to record topographic images at 40 ms intervals. A method of analysis of the dynamic changes in topography by use of Zernike polynomials enables a general distinction to be made between dynamic alterations in the shape of the cornea itself and the changes in the layer of the tears. The influence of deviations in the shape of the anterior surface of the eye on the retinal image is estimated.

Siedlecki, Damian; Kasprzak, Henryk; Pierscionek, Barbara K.

2007-03-01

44

The Development of a Degree 360 Expansion of the Dynamic Ocean Topography of the POCM_4B Global Circulation Model  

NASA Technical Reports Server (NTRS)

This paper documents the development of a degree 360 expansion of the dynamic ocean topography (DOT) of the POCM_4B ocean circulation model. The principles and software used that led to the final model are described. A key principle was the development of interpolated DOT values into land areas to avoid discontinuities at or near the land/ocean interface. The power spectrum of the POCM_4B is also presented with comparisons made between orthonormal (ON) and spherical harmonic magnitudes to degree 24. A merged file of ON and SH computed degree variances is proposed for applications where the DOT power spectrum from low to high (360) degrees is needed.

Rapp, Richard H.

1998-01-01

45

Structure and Dynamics of the Polar Regions of Mars from MGS Topography and Gravity  

NASA Technical Reports Server (NTRS)

The Mars Global Surveyor (MGS) spacecraft has been engaged in systematic mapping of Mars since insertion into Mars orbit in September, 1997. The objectives of the MGS mission are to globally map Mars as well as to quantify seasonal changes on the planet. MGS geophysical/geodetic observations of topography from the Mars Orbiter Laser Altimeter (MOLA) and gravity from the Radio Science investigation are providing significant new insights on both static and time-varying aspects of the polar regions of Mars. These observations have implications for polar processes on diurnal seasonal and climatic timescales. Thus far, MOLA has collected over 300 million precise measurements of Martian topography and cloud heights. The instrument has also provided measurements of the width of the backscattered optical pulse and of the 1064 nm reflectivity of the Martian surface and atmosphere. The along-track resolution of MOLA ground shots is approx. 300 m and the across-track spacing in the polar regions is a maximum of about four kilometers. The vertical accuracy of the topography is determined by the precision recovery of spacecraft orbits from the Radio Science investigation, which includes MOLA altimetry in the form of crossovers. This accuracy is currently approx. one meter. The gravity field is derived from X-band Doppler tracking with typical accuracy of 0.03 to 0.05 mm/s averaged over ten seconds. Current Mars gravity fields are to approximately degree and order 80 but are interpretable to the approximate degree and order 60 (spatial resolution < 180 km), which represents an estimate of the approximate coefficient limit of a field that can be produced without a power law constraint on the gravitational field inversion, which is commonly imposed for solution stability. Additional information is contained in the original extended abstract.

Zuber, Maria T.; Smith, David E.; Neumann, Gregory A.; Lemoine, Frank G.

2000-01-01

46

Absolute quantification of perfusion using dynamic susceptibility contrast MRI: pitfalls and possibilities  

Microsoft Academic Search

Absolute quantification of cerebral blood flow, cerebral blood volume and mean transit time is desirable in the determination\\u000a of tissue viability thresholds and tissue at risk in acute ischaemic stroke, as well as in cases where a global reduction\\u000a in cerebral blood flow is expected, for example, in patients with dementia or depressive disorders. Absolute values are also\\u000a useful when

Linda Knutsson; Freddy Ståhlberg; Ronnie Wirestam

2010-01-01

47

Large Eddy Simulation of atmospheric boundary layer flow over multi-scale topographies with a dynamic surface drag model  

NASA Astrophysics Data System (ADS)

Many flows especially in geophysical land surface-atmosphere coupling processes involve turbulent boundary layers over rough surfaces. Often these surfaces have multi-scale height distributions. For large eddy simulation (LES), when the filter scale is such that only the large-scale portion of the roughness elements of the surface can be resolved explicitly on the computational grid, new techniques need to be developed. Here we consider LES of flows over rough surfaces with power-law height spectra, as often encountered in natural terrains. In LES, the surface is decomposed into resolved and subgrid-scale height contributions. The effects of the unresolved small-scale height fluctuations are modeled using a local equilibrium wall model (log-law or Monin-Obukhov similarity), but specification of the required aerodynamic roughness length involves an ad-hoc parameter called the roughness parameter. A novel dynamic methodology is proposed based on test-filtering the surface forces and requiring that the total drag force be independent of filter scale or resolution. This dynamic surface roughness model is inspired by the Germano identity traditionally used to determine model parameters for closing subgrid-scale stresses in the bulk of a turbulent flow. A series of LES of fully developed flow over rough surfaces are performed. We firstly consider isotropic stochastic surfaces built using random-phase Fourier modes with prescribed power-law spectra. Results show that the approach yields well-defined, rapidly converging, values of the roughness parameter. Effects of spatial resolution and landscape spectral exponent are investigated. We also consider the case of two fluvial-like anisotropic landscapes. The first is a fluvial-like topography built through numerical solution of the Kardar-Parisi-Zhang equation. The second is rescaled topography (Texas) from the U.S. National Elevation Dataset. These landscapes are dominated by anisotropic modes that have emerged through geomorphological erosion processes. We find that the dynamic approach finds stable solutions also for surfaces with such anisotropies: results are most accurate for cases where the LES grid- and test-filter width are within the landscape 'self-similar' range. Weaknesses are reported for cases where spectral exponent changes with wavenumber, i.e. for cases with scale-dependence where the underlying assumption of the dynamic approach (scale-invariance) breaks down. Supported by NSF (AGS-1045189). We also acknowledge Profs. P. Passalacqua and F. Porte-Agel for providing the authors with KPZ solution fields for fluvial landscape applications.

Meneveau, C. V.; Anderson, W.

2011-12-01

48

Sea level change since the Pliocene - a new formalism for predicting sea level in the presence of dynamic topography and isostasy  

NASA Astrophysics Data System (ADS)

Dynamic topography (DT), as reflected in local sea level change, provides a unique lens for studying the imprint of deep Earth dynamics on the Earth's surface. The elevation of paleo-shorelines over long time scales is, however, not only perturbed by DT but also by glacial isostatic adjustment (GIA) and eustatic changes in sea level. Isolating these contributions is essential for efforts to constrain past changes in ice volume or mantle convection models. Previous studies have performed this separation by modeling dynamic topography and superimposing the signal on the elevation of a GIA-corrected paleo-shoreline. However, this approach neglects deformation of the Earth in response to changes in the ocean load and geometry driven by DT. We describe a generalized, gravitationally self-consistent framework for computing sea-level changes that incorporates DT and GIA. The formalism is based on a sea-level theory developed within the GIA community that takes accurate account of viscoelastic deformation of the solid Earth, perturbations in the gravity field, migration of shorelines and the feedback into sea-level of contemporaneous (load-induced) changes in Earth rotation. Specifically, dynamic topography is introduced as a perturbation to the elevation of the solid surface that does not load the Earth because it is dynamically supported. However, water that is displaced by DT is allowed to redistribute, perturb the gravitational field and load (or unload) the ocean floor wherever the water column is increased (or decreased). The problem is complicated by plate tectonics, which (in a tectonic reference frame) leaves changes in topography and DT undefined in areas of the ocean floor where plates have been subducted. We interpolate these regions by imposing mass conservation of both the solid Earth and water on the reconstructed topography. We use the new formalism to calculate sea level change since the mid-Pliocene (3 Ma) using recent global simulations of dynamic topography that are constrained to fit a large suite of modern geophysical observables. We demonstrate that the results differ significantly from calculations in which dynamic topography is simply added to the elevation of GIA-corrected paleo-shorelines. Moreover, we apply these results to new paleo-shoreline data of Pliocene age from the US east coast, South Africa and southwest Australia to estimate peak eustatic sea level (and, thus, minimum ice volume) during the Mid Pliocene Warm Period.

Austermann, Jacqueline; Rovere, Alessio; Moucha, Robert; Mitrovica, Jerry X.; Rowley, David B.; Forte, Alessandro M.; Raymo, Maureen E.

2014-05-01

49

Effects of dynamic vegetation and topography on hydrological processes in semi-arid areas  

E-print Network

Ecosystems of dry climates represent a particularly interesting object for ecohydrological studies, as water is generally considered to be the key limiting resource. This work focuses on vegetation-water-energy dynamics ...

Ivanov, Valeri Yuryevich, 1974-

2006-01-01

50

Future Antarctic bed topography and its implications for ice sheet dynamics  

NASA Astrophysics Data System (ADS)

The Antarctic bedrock is evolving as the solid Earth responds to the past and ongoing evolution of the ice sheet. A~recently improved ice loading history suggests that the Antarctic Ice Sheet (AIS) is generally losing its mass since the last glacial maximum (LGM). In a sustained warming climate, the AIS is predicted to retreat at a greater pace primarily via melting beneath the ice shelves. We employ the glacial isostatic adjustment (GIA) capability of the Ice Sheet System Model (ISSM) to combine these past and future ice loadings and provide the new solid Earth computations for the AIS. We find that the past loading is relatively less important than future loading on the evolution of the future bed topography. Our computations predict that the West Antarctic Ice Sheet (WAIS) may uplift by a few meters and a few tens of meters at years 2100 and 2500 AD, respectively, and that the East Antarctic Ice Sheet (EAIS) is likely to remain unchanged or subside minimally except around the Amery Ice Shelf. The Amundsen Sea Sector in particular is predicted to rise at the greatest rate; one hundred years of ice evolution in this region, for example, predicts that the coastline of Pine Island Bay approaches roughly 45 mm yr-1 in viscoelastic vertical motion. Of particular importance, we systematically demonstrate that the effect of a pervasive and large GIA uplift in the WAIS is associated with the flattening of reverse bed, reduction of local sea depth, and thus the extension of grounding line (GL) towards the continental shelf. Using the 3-D higher-order ice flow capability of ISSM, such a migration of GL is shown to inhibit the ice flow. This negative feedback between the ice sheet and the solid Earth may promote the stability to marine portions of the ice sheet in future.

Adhikari, S.; Ivins, E.; Larour, E.; Seroussi, H.; Morlighem, M.; Nowicki, S.

2014-01-01

51

Future Antarctic bed topography and its implications for ice sheet dynamics  

NASA Astrophysics Data System (ADS)

A recently improved ice loading history suggests that the Antarctic Ice Sheet (AIS) has been generally losing its mass since the last glacial maximum. In a sustained warming climate, the AIS is predicted to retreat at a greater pace primarily via melting beneath the ice shelves. We employ the glacial isostatic adjustment (GIA) capability of the Ice Sheet System Model (ISSM) to combine these past and future ice loadings and provide the new solid Earth computations for the AIS. We find that the past loading is relatively less important than future loading on the evolution of the future bed topography. Our computations predict that the West Antarctic Ice Sheet (WAIS) may uplift by a few meters and a few tens of meters at years 2100 and 2500 AD, respectively, and that the East Antarctic Ice Sheet (EAIS) is likely to remain unchanged or subside minimally except around the Amery Ice Shelf. The Amundsen Sea Sector of WAIS in particular is predicted to rise at the greatest rate; one hundred years of ice evolution in this region, for example, predicts that the coastline of Pine Island Bay approaches roughly 45 mm/yr in viscoelastic vertical motion. Of particular importance, we systematically demonstrate that the effect of a pervasive and large GIA uplift in the WAIS is associated with the flattening of reverse bed, reduction of local sea depth, and thus the extension of grounding line (GL) towards the continental shelf. Using the 3-D higher-order ice flow capability of ISSM, such a migration of GL is shown to inhibit the ice flow. This negative feedback between the ice sheet and the solid Earth may promote the stability to marine portions of the ice sheet in the future.

Adhikari, Surendra; Ivins, Erik; Larour, Eric; Seroussi, Helene; Morlighem, Mathieu; Nowicki, Sophie

2014-05-01

52

Future Antarctic bed topography and its implications for ice sheet dynamics  

NASA Astrophysics Data System (ADS)

The Antarctic bedrock is evolving as the solid Earth responds to the past and ongoing evolution of the ice sheet. A recently improved ice loading history suggests that the Antarctic Ice Sheet (AIS) has generally been losing its mass since the Last Glacial Maximum. In a sustained warming climate, the AIS is predicted to retreat at a greater pace, primarily via melting beneath the ice shelves. We employ the glacial isostatic adjustment (GIA) capability of the Ice Sheet System Model (ISSM) to combine these past and future ice loadings and provide the new solid Earth computations for the AIS. We find that past loading is relatively less important than future loading for the evolution of the future bed topography. Our computations predict that the West Antarctic Ice Sheet (WAIS) may uplift by a few meters and a few tens of meters at years AD 2100 and 2500, respectively, and that the East Antarctic Ice Sheet is likely to remain unchanged or subside minimally except around the Amery Ice Shelf. The Amundsen Sea Sector in particular is predicted to rise at the greatest rate; one hundred years of ice evolution in this region, for example, predicts that the coastline of Pine Island Bay will approach roughly 45 mm yr-1 in viscoelastic vertical motion. Of particular importance, we systematically demonstrate that the effect of a pervasive and large GIA uplift in the WAIS is generally associated with the flattening of reverse bed slope, reduction of local sea depth, and thus the extension of grounding line (GL) towards the continental shelf. Using the 3-D higher-order ice flow capability of ISSM, such a migration of GL is shown to inhibit the ice flow. This negative feedback between the ice sheet and the solid Earth may promote stability in marine portions of the ice sheet in the future.

Adhikari, S.; Ivins, E. R.; Larour, E.; Seroussi, H.; Morlighem, M.; Nowicki, S.

2014-06-01

53

Dynamics of plasma formation, relaxation, and topography modification induced by femtosecond laser pulses in crystalline and amorphous dielectrics  

SciTech Connect

We have studied plasma formation and relaxation dynamics along with the corresponding topography modifications in fused silica and sapphire induced by single femtosecond laser pulses (800 nm and 120 fs). These materials, representative of high bandgap amorphous and crystalline dielectrics, respectively, require nonlinear mechanisms to absorb the laser light. The study employed a femtosecond time-resolved microscopy technique that allows obtaining reflectivity and transmission images of the material surface at well-defined temporal delays after the arrival of the pump pulse which excites the dielectric material. The transient evolution of the free-electron plasma formed can be followed by combining the time-resolved optical data with a Drude model to estimate transient electron densities and skin depths. The temporal evolution of the optical properties is very similar in both materials within the first few hundred picoseconds, including the formation of a high reflectivity ring at about 7 ps. In contrast, at longer delays (100 ps-20 ns) the behavior of both materials differs significantly, revealing a longer lasting ablation process in sapphire. Moreover, transient images of sapphire show a concentric ring pattern surrounding the ablation crater, which is not observed in fused silica. We attribute this phenomenon to optical diffraction at a transient elevation of the ejected molten material at the crater border. On the other hand, the final topography of the ablation crater is radically different for each material. While in fused silica a relatively smooth crater with two distinct regimes is observed, sapphire shows much steeper crater walls, surrounded by a weak depression along with cracks in the material surface. These differences are explained in terms of the most relevant thermal and mechanical properties of the material. Despite these differences the maximum crater depth is comparable in both material at the highest fluences used (16 J/cm{sup 2}). The evolution of the crater depth as a function of fluence can be described taking into account the individual bandgap of each material.

Puerto, D.; Siegel, J.; Gawelda, W.; Galvan-Sosa, M.; Solis, J. [Laser Processing Group, Instituto de Optica-CSIC, Madrid (Spain); Ehrentraut, L. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie, Berlin (Germany); Bonse, J. [Bundesanstalt fuer Materialforschung und-pruefung (BAM), Berlin (Germany)

2010-05-15

54

Effects of bottom topography on dynamics of river discharges in tidal regions: case study of twin plumes in Taiwan Strait  

NASA Astrophysics Data System (ADS)

The Princeton Ocean Model (POM) is used to investigate the intratidal variability of currents and turbulent mixing and their impact on the characteristics and evolution of the plumes of two neighbouring rivers, the Zhuoshui River and the Wu River, at the central eastern coast of Taiwan Strait. The two estuaries are located close to each other and their conditions are similar in many respects, and yet the two plumes exhibit significantly different behaviour. We explain this through differences of the bottom topography in the areas adjacent to the two river mouths. The Zhuoshui River runs into a shallow area that is permanently exposed to strong tidal mixing, while the Wu River mouth is located in a deeper, stratified area outside the region of intense mixing. This destruction of the plume by tidal mixing is confirmed by the results of numerical modeling with POM. The spatial and temporal variability of turbulent kinetic energy, the rates of its production by shear and destruction rate by buoyancy in the study, as well as the horizontal diffusivity, are analysed with the emphasis given to the dependence of the turbulence parameters on the bottom topography on the one hand and their influence on the river plumes on the other. The results of the study support the central hypothesis of this paper: the dynamic behaviours of the Zhuoshui and Wu plumes are different because their evolution occurs under different regimes of bottom-generated turbulent mixing. Further, we use a Lagrangian particle tracking model in combination with POM to investigate the effect of the tidal wetting-and-drying (WAD) near the Zhuoshui River estuary, and demonstrate that WAD leads to significant reduction of the plume extent and surface salinity deficit near the river mouth. We use observational data from a short field campaign in the study area to tune and validate the model experiments.

Korotenko, K. A.; Osadchiev, A. A.; Zavialov, P. O.; Kao, R.-C.; Ding, C.-F.

2014-10-01

55

New Clinical Instrument for The Early Detection of Cataract Using Dynamic Light Scattering and Corneal Topography.  

National Technical Information Service (NTIS)

A growing cataract can be detected at the molecular level using the technique of dynamic light scattering (DLS). However, the success of this method in clinical use depends upon the precise control of the scattering volume inside a patient's eye and espec...

J. F. King, M. B. Datiles, R. R. Ansari

2000-01-01

56

Wasp-waist populations and marine ecosystem dynamics: Navigating the “ predator pit” topographies  

NASA Astrophysics Data System (ADS)

Many marine ecosystems exhibit a characteristic “wasp-waist” structure, where a single species, or at most several species, of small planktivorous fishes entirely dominate their trophic level. These species have complex life histories that result in radical variability that may propagate to both higher and lower trophic levels of the ecosystem. In addition, these populations have two key attributes: (1) they represent the lowest trophic level that is mobile, so they are capable of relocating their area of operation according to their own internal dynamics; (2) they may prey upon the early life stages of their predators, forming an unstable feedback loop in the trophic system that may, for example, precipitate abrupt regime shifts. Experience with the typical “boom-bust” dynamics of this type of population, and with populations that interact trophically with them, suggests a “predator pit” type of dynamics. This features a refuge from predation when abundance is very low, very destructive predation between an abundance level sufficient to attract interest from predators and an abundance level sufficient to satiate available predators, and, as abundance increases beyond this satiation point, decreasing specific predation mortality and population breakout. A simple formalism is developed to describe these dynamics. Examples of its application include (a) a hypothetical mechanism for progressive geographical habitat expansion at high biomass, (b) an explanation for the out-of-phase alternations of abundances of anchovies and sardines in many regional systems that appear to occur without substantial adverse interactions between the two species groups, and (c) an account of an interaction of environmental processes and fishery exploitation that caused a regime shift. The last is the example of the Baltic Sea, where the cod resource collapsed in concert with establishment of dominance of that ecosystem by the cod’s ‘wasp-waist” prey, herring and sprat.

Bakun, Andrew

2006-02-01

57

Corneal topography  

Microsoft Academic Search

This paper explores the many aspects of the nature and measurement of the corneal surface. Its structure and the factors that influence it are described. The traditional techniques of keratometry are summarized and there is an emphasis on new experimental methods of determining corneal topography including moiré, holographic interferometric and profile techniques. The advantages and disadvantages of these procedures are

Thomas W. Smith

1977-01-01

58

A New Clinical Instrument for The Early Detection of Cataract Using Dynamic Light Scattering and Corneal Topography  

NASA Technical Reports Server (NTRS)

A growing cataract can be detected at the molecular level using the technique of dynamic light scattering (DLS). However, the success of this method in clinical use depends upon the precise control of the scattering volume inside a patient's eye and especially during patient's repeat visits. This is important because the scattering volume (cross-over region between the scattered fight and incident light) inside the eye in a high-quality DLS set-up is very small (few microns in dimension). This precise control holds the key for success in the longitudinal studies of cataract and during anti-cataract drug screening. We have circumvented these problems by fabricating a new DLS fiber optic probe with a working distance of 40 mm and by mounting it inside a cone of a corneal analyzer. This analyzer is frequently used in mapping the corneal topography during PRK (photorefractive keratectomy) and LASIK (laser in situ keratomileusis) procedures in shaping of the cornea to correct myopia. This new instrument and some preliminary clinical tests on one of us (RRA) showing the data reproducibility are described.

Ansari, Rafat R.; Datiles, Manuel B., III; King, James F.

2000-01-01

59

Determination of some dominant parameters of the global dynamic sea surface topography from GEOS-3 altimetry  

NASA Technical Reports Server (NTRS)

The 1977 altimetry data bank is analyzed for the geometrical shape of the sea surface expressed as surface spherical harmonics after referral to the higher reference model defined by GEM 9. The resulting determination is expressed as quasi-stationary dynamic SST. Solutions are obtained from different sets of long arcs in the GEOS-3 altimeter data bank as well as from sub-sets related to the September 1975 and March 1976 equinoxes assembled with a view to minimizing seasonal effects. The results are compared with equivalent parameters obtained from the hydrostatic analysis of sporadic temperature, pressure and salinity measurements of the oceans and the known major steady state current systems with comparable wavelengths. The most clearly defined parameter (the zonal harmonic of degree 2) is obtained with an uncertainty of + or - 6 cm. The preferred numerical value is smaller than the oceanographic value due to the effect of the correction for the permanent earth tide. Similar precision is achieved for the zonal harmonic of degree 3. The precision obtained for the fourth degree zonal harmonic reflects more closely the accuracy expected from the level of noise in the orbital solutions.

Mather, R. S.; Lerch, F. J.; Rizos, C.; Masters, E. G.; Hirsch, B.

1978-01-01

60

Setting the absolute tempo of biodiversity dynamics Andrew P. Allen1  

E-print Network

data that encompass 30 Myr of macroevolution for planktonic foraminifera. By synthesizing the model dynamics. Keywords Demographic stochasticity, environmental stochasticity, extinction, macroevolution

Allen, Andrew P.

61

The scale and time dependence of surface dynamic topography over the last 200 million years in the Atlantic and Indian ocean domains  

NASA Astrophysics Data System (ADS)

We evaluate the evolution of large-scale surface dynamic topography in the Atlantic and Indian Ocean domains using a mantle convection model constrained by a global tectonic model for the time period from 200 Ma to the present. We use the GPlates software to implement a global plate motion model with tectonic plates being represented as an interlocking set of closed topological polygons which evolve through time in a self-consistent manner. We generate plate velocity meshes as surface boundary conditions in 1 million year intervals to impose plate motions on a mantle convection model in order to study the driving factors of surface dynamic topography computed with CitcomS. We implement a mantle rheology with an upper-lower mantle viscosity contrast of 1:100, consistent with other observations constraining this ratio. We use a slab assimilation method in which the thermal structure of the slab, derived analytically, is progressively assimilated in the upper mantle into the dynamic models, improving the continuity of sinking slabs in the mantle. The models generate a global flow and dynamic topography pattern with hemispheric upwellings focused on the antipodal low-velocity seismic-shear-wave regions above the core-mantle boundary, even though these are not imposed on our model. Combined subduction along the western Pacific and northern Tethys margins drives a pronounced return flow centered on the reconstructed position of India in the Cretaceous, resulting in positive dynamic topography from India and Madagascar to the southeastern African margin. After 50 Ma a strong secondary surface topography high becomes established in the North Atlantic, straddling the margins of Northwest Africa and western Europe. This broadly coincides with the onset of alkali volcanism in central/southern Europe, north Africa, and the eastern central North Atlantic. Previous work on this widely-distributed small-scale volcanism had suggested that it may correspond to a broad mantle upwelling in response to a mantle avalanche. Our models suggest that it is rather the consequence of the time-dependence of subduction and associated mantle return flow on both sides of the Atlantic without the necessity for avalanches. Our model predict large-scale dynamic subsidence for both the Arabian peninsula as well as India during the Cenozoic as they move from a mantle upwelling into the downwelling region associated with the closure of the Meso-Tethys. Our model also predicts enhanced uplift of southern Africa during the last 30 million years, as well as major asymmetries not only in conjugate margin evolution but also along-strike passive margins especially where they straddle boundaries between large-scale upwellings and downwellings through time.

Müller, R. D.; Flament, N.; Gurnis, M.

2012-04-01

62

Who is in control? Competing influences of geology, land use and topography on soil moisture and soil temperature dynamics  

NASA Astrophysics Data System (ADS)

Can we identify distinct signatures of landscape elements in the event response of soil moisture and soil temperature? Moisture and temperature dynamics in soils are largely controlled by the climatic boundary conditions of rainfall, evapotranspiration and radiation. However, certain landscape features also leave characteristic finger prints on soil moisture and soil temperature time series. The extent of these influences and their time variable relative importance are important in a number of contexts, such as landscape scale prediction of soil moisture patterns or runoff generation, process predictions in ungauged basins or the improvement of hydrological model structures for the mesoscale. The competing influences of geology, land use and topography on temperature and moisture characteristics in the vadose zone are explored at the CAOS hydrological observatory in Luxemburg (http://www.caos-project.de/) with a unique experimental setup of 45 sensor clusters. These sensor clusters cover three different geologies (schist, sandstone, marls), two land use classes (forest and grassland), five different landscape positions (plateau, top-, mid- and lower hillslope as well as near stream/floodplain locations), and contrasting expositions. At each of these sensor clusters three soil moisture profiles with sensors at depths from 10 to 70 cm, four soil temperature profiles as well as air temperature, relative humidity, global radiation, rainfall/throughfall, sapflow and shallow groundwater and stream water levels were measured continuously. Time series of up to 2 years for the schist region and up to 6 months for the complete set of sites allow for a first intercomparison of characteristic event response behavior.

Blume, Theresa; Hassler, Sibylle; Weiler, Markus

2014-05-01

63

Coseismic temporal changes of slip direction: the effect of absolute stress on dynamic rupture  

USGS Publications Warehouse

We investigate the dynamics of rupture at low-stress level. We show that one main difference between the dynamics of high- and low-stress events is the amount of coseismic temporal rake rotation occurring at given points on the fault. Curved stations on exposed fault surfaces and earthquake dislocation models derived from ground-motion inversion indicate that the slip direction may change with time at a pointon the fault during dynamic rupture. We use a 3D boundary integral method to model temporal rake variations during dynamic rupture propagation assuming a slip-weakening friction law and isotropic friction. The points at which the slip rotates most are characterized by an initial shear stress direction substantially different from the average stress direction over the fault plane. We show that for a given value of stress drop, the level of initial shear stress (i.e., the fractional stress drop) determines the amount of rotation in slip direction. We infer that seismic events that show evidence of temporal rake rorations are characterized by a low initial shear-stress level with spatially variable direction on the fault (possibly due to changes in fault surface geometry) and an almost complete stress drop. Our models motivate a new interpretation of curved and cross-cutting striations and put new constraints on their analysis. The initial rake is in general collinear with the initial stress at the hypocenter zone, supporting the assumptions made in stress-tensor inversion from first-motion analysis. At other points on the fualt, especially away from the hypocenter, the initial slip rake may not be collinear with the initial shear stress, contradicting a common assumption of structural geology. On the other hand, the later part of slip in our models is systematically more aligned withi the average stress direction than the early slip. Our modeling suggests that the length of the straight part of curved striations is usually an upper bound of the slip-weakening distance is this parameter is uniform over the fault plane, and the direction of the late part of slip of curved striations should have more weight in the estimate of initial stress direction.

Guatteri, M.; Spudich, P.

1998-01-01

64

New visualization strategy to study the dynamics of surgical coagulation devices in biological tissue using absolute subsurface thermal imaging  

NASA Astrophysics Data System (ADS)

Visualisation of the thermo dynamics of surgical coagulation devices like laser, diathermy and RFA devices in tissue are essential to get better understanding about the principles of operation of these devices. Thermo cameras have the ability to measure absolute temperatures. However, the visualization of temperature fields using thermal imaging has always been limited to the surface of a medium. We have developed a new strategy to look below the surface of biological tissue by viewing through a ZincSelenide window positioned alongside a block of tissue. When exposed from above with an energy source, the temperature distribution below the surface can be observed through the window. To obtain a close-up view, the thermo camera is enhanced with special macro optics. The thermo dynamics during tissue interaction of various electro surgery modes was studied in biological tissues to obtain a better understanding of the working mechanism. Simultaneously with thermal imaging, normal close-up video footage was obtained to support the interpretation of the thermal imaging. For comparison, temperature gradients were imaged inside a transparent tissue model using color Schlieren imaging. The new subsurface thermal imaging method gives a better understanding of interaction of thermal energy of surgical devices and contributes to the safety and the optimal settings for various medical applications. However, the technique has some limitations that have to be considered. The three imaging modalities showed to be both compatible and complementary showing the pro- and cons- of each modality.

Been, Stefan L.; Verdaasdonk, Rudolf M.; Klaessens, John H. G. M.

2011-03-01

65

Absolutely relativity  

NASA Astrophysics Data System (ADS)

The light speed constancy is proved here and then it is not a principle suppose it is a proposition proved absolutely based on the Galilean transformation and simultaneity and this is a book full from new discoveries along the absolutely proof for Lorentz transformation. Even in a page I have proved Lorentz transformation by the brawer constant point based on the Galilean transformation until to show easily it is possible to generate absolutely relativity and this is not ether theorem suppose we are upon the new discoveries all mathematical and complete, not a theory.

Lutephy, Mohsen

2012-03-01

66

Free Energy Perturbation Hamiltonian Replica-Exchange Molecular Dynamics (FEP\\H-REMD) for absolute ligand binding free energy calculations.  

SciTech Connect

Free Energy Perturbation with Replica Exchange Molecular Dynamics (FEP/REMD) offers a powerful strategy to improve the convergence of free energy computations. In particular, it has been shown previously that a FEP/REMD scheme allowing random moves within an extended replica ensemble of thermodynamic coupling parameters '{lambda}' can improve the statistical convergence in calculations of absolute binding free energy of ligands to proteins [J. Chem. Theory Comput. 2009, 5, 2583]. In the present study, FEP/REMD is extended and combined with an accelerated MD simulations method based on Hamiltonian replica-exchange MD (H-REMD) to overcome the additional problems arising from the existence of kinetically trapped conformations within the protein receptor. In the combined strategy, each system with a given thermodynamic coupling factor {lambda} in the extended ensemble is further coupled with a set of replicas evolving on a biased energy surface with boosting potentials used to accelerate the interconversion among different rotameric states of the side chains in the neighborhood of the binding site. Exchanges are allowed to occur alternatively along the axes corresponding to the thermodynamic coupling parameter {lambda} and the boosting potential, in an extended dual array of coupled {lambda}- and H-REMD simulations. The method is implemented on the basis of new extensions to the REPDSTR module of the biomolecular simulation program CHARMM. As an illustrative example, the absolute binding free energy of p-xylene to the nonpolar cavity of the L99A mutant of the T4 lysozyme was calculated. The tests demonstrate that the dual {lambda}-REMD and H-REMD simulation scheme greatly accelerates the configurational sampling of the rotameric states of the side chains around the binding pocket, thereby improving the convergence of the FEP computations.

Jiang, W.; Roux, B. (Biosciences Division); (Univ. of Chicago)

2010-09-01

67

Does Dynamical Downscaling Introduce Novel Information in Climate Model Simulations of Recipitation Change over a Complex Topography Region?  

NASA Technical Reports Server (NTRS)

Current climate and future climate-warming runs with the RegCM Regional Climate Model (RCM) at 50 and 11 km-resolutions forced by the ECHAM GCM are used to examine whether the increased resolution of the RCM introduces novel information in the precipitation field when the models are run for the mountainous region of the Hellenic peninsula. The model results are inter-compared with the resolution of the RCM output degraded to match that of the GCM, and it is found that in both the present and future climate runs the regional models produce more precipitation than the forcing GCM. At the same time, the RCM runs produce increases in precipitation with climate warming even though they are forced with a GCM that shows no precipitation change in the region. The additional precipitation is mostly concentrated over the mountain ranges, where orographic precipitation formation is expected to be a dominant mechanism. It is found that, when examined at the same resolution, the elevation heights of the GCM are lower than those of the averaged RCM in the areas of the main mountain ranges. It is also found that the majority of the difference in precipitation between the RCM and the GCM can be explained by their difference in topographic height. The study results indicate that, in complex topography regions, GCM predictions of precipitation change with climate warming may be dry biased due to the GCM smoothing of the regional topography.

Tselioudis, George; Douvis, Costas; Zerefos, Christos

2012-01-01

68

Seismic waveform inversion for core-mantle boundary topography  

NASA Astrophysics Data System (ADS)

The topography of the core-mantle boundary (CMB) is directly linked to the dynamics of both the mantle and the outer core, although it is poorly constrained and understood. Recent studies have produced topography models with mutual agreement up to degree 2. A broad-band waveform inversion strategy is introduced and applied here, with relatively low computational cost and based on a first-order Born approximation. Its performance is validated using synthetic waveforms calculated in theoretical earth models that include different topography patterns with varying lateral wavelengths, from 600 to 2500 km, and magnitudes (˜10 km peak-to-peak). The source-receiver geometry focuses mainly on the Pdiff, PKP, PcP and ScS phases. The results show that PKP branches, PcP and ScS generally perform well and in a similar fashion, while Pdiff yields unsatisfactory results. We investigate also how 3-D mantle correction influences the output models, and find that despite the disturbance introduced, the models recovered do not appear to be biased, provided that the 3-D model is correct. Using cross-correlated traveltimes, we derive new topography models from both P and S waves. The static corrections used to remove the mantle effect are likely to affect the inversion, compromising the agreement between models derived from P and S data. By modelling traveltime residuals starting from sensitivity kernels, we show how the simultaneous use of volumetric and boundary kernels can reduce the bias coming from mantle structures. The joint inversion approach should be the only reliable method to invert for CMB topography using absolute cross-correlation traveltimes.

Colombi, Andrea; Nissen-Meyer, Tarje; Boschi, Lapo; Giardini, Domenico

2014-07-01

69

Constraining the Absolute Orientation of eta Carinae's Binary Orbit: A 3-D Dynamical Model for the Broad [Fe III] Emission  

NASA Technical Reports Server (NTRS)

We present a three-dimensional (3-D) dynamical model for the broad [Fe III] emission observed in Eta Carinae using the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS). This model is based on full 3-D Smoothed Particle Hydrodynamics (SPH) simulations of Eta Car's binary colliding winds. Radiative transfer codes are used to generate synthetic spectro-images of [Fe III] emission line structures at various observed orbital phases and STIS slit position angles (PAs). Through a parameter study that varies the orbital inclination i, the PA(theta) that the orbital plane projection of the line-of-sight makes with the apastron side of the semi-major axis, and the PA on the sky of the orbital axis, we are able, for the first time, to tightly constrain the absolute 3-D orientation of the binary orbit. To simultaneously reproduce the blue-shifted emission arcs observed at orbital phase 0.976, STIS slit PA = +38deg, and the temporal variations in emission seen at negative slit PAs, the binary needs to have an i approx. = 130deg to 145deg, Theta approx. = -15deg to +30deg, and an orbital axis projected on the sky at a P A approx. = 302deg to 327deg east of north. This represents a system with an orbital axis that is closely aligned with the inferred polar axis of the Homunculus nebula, in 3-D. The companion star, Eta(sub B), thus orbits clockwise on the sky and is on the observer's side of the system at apastron. This orientation has important implications for theories for the formation of the Homunculus and helps lay the groundwork for orbital modeling to determine the stellar masses.

Madura, T. I.; Gull, T. R.; Owocki, S. P.; Groh, J. H.; Okazaki, A. T.; Russell, C. M. P.

2011-01-01

70

Density Isostasy and Topography  

NSDL National Science Digital Library

Density, Isostasy, and Topography Anne Egger, Stanford University The original activity Density, Isostasy, and Topography already exists within the SERC website. This page describes how this activity can be used ...

71

Moiré topography in odontology  

Microsoft Academic Search

For several decades, measurement of optical techniques has been used in different branches of science and technology. One of these techniques is the so-called moiré topography (MT) that enables the accurate measurement of different parts of the human body topography. This investigation presents the measurement of topographies of teeth and gums using an automated system of shadow moiré and the

A. Moreno Yeras

2003-01-01

72

Two-Phase Thermodynamic Model for Efficient and Accurate Absolute Entropy of Water from Molecular Dynamics Simulations  

E-print Network

to study the properties of water under various physical and chemical environments around biological mol properties from MD simulations. 1. Introduction The thermodynamic properties of water (especially the energyTwo-Phase Thermodynamic Model for Efficient and Accurate Absolute Entropy of Water from Molecular

Goddard III, William A.

73

Dynamics and Topography of QUASI-2D Needle-Like Silver Electrochemical Deposits Under a Quasi-Steady Regime  

NASA Astrophysics Data System (ADS)

The electrochemical formation of single silver needles from aqueous silver sulfate was studied under both potentiostatic and galvanostatic conditions utilizing different quasi-2D cells. Under potentiostatic conditions, four (I-IV) stages of growth were distinguished. Stage III involved single needle growth under a quasi-steady-state (q-ss) regime in which, at the millimeter scale, the tip profile remained almost unchanged. Fast growing needles exhibited a truncated quasi-conical tip, and slow growing ones approached prolate hemispheroids. At stage III, the almost constant q-ss silver deposition rate was evaluated from the tip front displacement (dLz/dt) perpendicularly to the tangential plane of the tip. For the cathode to anode potential difference in the range -1.00 ? Ec-a ? -0.22 V, values of (dLz/dt) in the range 0.08-2.0 ?m s-1 were obtained. At the needle stem, the q-ss radial silver deposition rate (dLx/dt) was about two orders of magnitude lower than (dLz/dt). The transition from stage III to IV was characterized by tip thickening, i.e. a change in the tip q-conical profile to that of a prolate hemispheroid, and eventual tip splitting. Scanning electron micrographs at the micrometer scale of single silver needle tips from potentiostatic runs showed either a defined crystallography or an irregular topography covered by a large number of tiny crystals. In contrast, stems were always faceted. This difference indicated that surface relaxation processes following silver ion mass transport and discharge played a relevant role in the needle growth mode. At stage III, the growth regime is described utilizing a dual diffusion (D) and migration (M) model consisting of a DM direct contribution that becomes dominant at the needle stem, and a space charge (SC)-assisted DM contribution that operates at the tip apex. This explanation is consistent with the local cathodic current density values, the concentration ratio of silver clusters at the stem and tip apex surface, and the distinct kinetic behavior of needles produced from potentiostatic and galvanostatic runs. The complex link between mass transport phenomena of silver ions from the binary solution side, the silver ion discharge at the interface and the surface relaxation of silver adatoms and clusters at the metal lattice shed new light on the aspects of single silver needle formation.

Pasquale, M. A.; Vicente, J. L.; Arvia, A. J.

74

The combined effects of topography and vegetation on catchment connectivity  

NASA Astrophysics Data System (ADS)

The deconvolution of whole catchment runoff response into its temporally dynamic source areas is a grand challenge in hydrology. The extent to which the intersection of static and dynamic catchment characteristics (e.g. topography and vegetation) influences water redistribution within a catchment and the hydrologic connectivity of hillslopes to the riparian and stream system is largely unknown. Over time, patterns of catchment storage shift and, because of threshold connectivity behavior, catchment areas become disconnected from the stream network. We developed a simple but spatially distributed modeling framework that explicitly incorporates static (topography) and dynamic (vegetation) catchment structure to document the evolution of catchment connectivity over the course of a water year. We employed directly measured eddy-covariance evapotranspiration data co-located within a highly instrumented (>150 recording groundwater wells) and gauged catchment to parse the effect of current and zero vegetation scenarios on the temporal evolution of hydrologic connectivity. In the absence of vegetation, and thus in the absence of evapotranspiration, modeled absolute connectivity was 4.5% greater during peak flow and 3.9% greater during late summer baseflow when compared to the actual vegetation scenario. The most significant differences in connected catchment area between current and zero vegetation (14.9%) occurred during the recession period in early July, when water and energy availability were at an optimum. However, the greatest relative difference in connected area occurs during the late summer baseflow period when the absence of evapotranspiration results in a connected area approximately 500% greater than when vegetation is present, while the relative increase during peak flow is just 6%. Changes in connected areas ultimately lead to propose a biologically modified geomorphic width function. This biogeomorphic width function is the result of lateral water redistribution driven by topography and water uptake by vegetation.

Nippgen, F.; McGlynn, B. L.; Emanuel, R. E.

2012-12-01

75

Satellite Remote Sensing of Landscape Freeze/Thaw State Dynamics for Complex Topography and Fire Disturbance Areas Using Multi-Sensor Radar and SRTM Digital Elevation Models  

NASA Astrophysics Data System (ADS)

The annual freeze/thaw cycle drives the length of the growing season in the boreal forest, and is a major factor determining annual productivity and associated exchange of CO2 with the atmosphere. Variations in freeze/thaw processes are spatially and temporally complex in boreal environments, particularly in areas of complex topography and in fire disturbance regimes. We investigate the spatial and temporal characteristics of seasonal freeze/thaw dynamics in complex boreal landscapes, as derived from radar backscatter measured with ERS (C-band, VV polarization, 200m resolution) and JERS-1 (L-band, HH polarization, 100m resolution) Synthetic Aperture Radars (SARs), and with the SeaWinds scatterometer (Ku-band, 25km resolution). C- and L-band backscatter are applied to characterize freeze/thaw transitions for a chronosequence of recovering burn sites near Delta Junction, Alaska, and for a region of complex topography on the Kenai Peninsula, Alaska. We characterize differences in radar-derived freeze/thaw state, examining transitions over complex terrain and landscape disturbance regimes. In areas of complex terrain, we explore freeze/thaw dynamics related to elevation, slope aspect and varying landcover. In the burned regions, we explore the timing of seasonal freeze/thaw transition as related to the recovering landscape, relative to that of a nearby control site. We apply in situ biophysical measurements, including flux tower measurements to validate and interpret the remotely sensed parameters. A multi-scale analysis is performed relating high-resolution SAR backscatter and moderate resolution scatterometer measurements to assess trade-offs in spatial and temporal resolution in the remotely sensed fields. A temporal change discriminator is applied to classify time series radar imagery to classify the landscape freeze-thaw state. We apply a 30m-resolution digital elevation model (DEM) derived from Shuttle Radar Topography Mission (SRTM) data to orthorectify the time series SAR imagery over the complex terrain site. This DEM was integrated with the SAR imagery to examine elevation and slope aspect effects on freeze/thaw transitions. Scaling assessments of the relationship between SAR and SeaWinds backscatter provide a means for determining sub-grid spatial variability in land cover, terrain and freeze/thaw processes, based on semi-variogram analyses. Results show that the high-resolution SARs may be applied to map freeze/thaw transitions in complex landscapes. In regions of complex terrain, dynamics related to elevation and slope aspect are delineated. Fusion with accurate DEM information as provided by SRTM facilitates orthorectification and analysis of terrain effects. The SARs also observe distinguishable differences in backscatter amplitude response and in the timing of freeze/thaw transitions associated with varying disturbance regimes driven by forest fire. These findings demonstrate the importance of considering landscape heterogeneity for development of remote sensing techniques for monitoring phenological processes across complex, heterogeneous landscapes in boreal ecosystems. This work was performed at the Jet Propulsion Laboratory, California Institute of Technology, and the University of Montana under contract with the National Aeronautics and Space Administration.

Podest, E.; McDonald, K.; Kimball, J.; Randerson, J. T.

2003-12-01

76

Plasma radiation dynamics with the upgraded Absolute Extreme Ultraviolet tomographical system in the Tokamak à Configuration Variable  

SciTech Connect

We introduce an upgraded version of a tomographical system which is built up from Absolute Extreme Ultraviolet-type (AXUV) detectors and has been installed on the Tokamak à Configuration Variable (TCV). The system is suitable for the investigation of fast radiative processes usually observed in magnetically confined high-temperature plasmas. The upgrade consists in the detector protection by movable shutters, some modifications to correct original design errors and the improvement in the data evaluation techniques. The short-term sensitivity degradation of the detectors, which is caused by the plasma radiation itself, has been monitored and found to be severe. The results provided by the system are consistent with the measurements obtained with the usual plasma radiation diagnostics installed on TCV. Additionally, the coupling between core plasma radiation and plasma-wall interaction is revealed. This was impossible with other available diagnostics on TCV.

Tal, B.; Nagy, D.; Veres, G. [Institute for Particle and Nuclear Physics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Association EURATOM, P. O. Box 49, H-1525 Budapest (Hungary)] [Institute for Particle and Nuclear Physics, Wigner Research Centre for Physics, Hungarian Academy of Sciences, Association EURATOM, P. O. Box 49, H-1525 Budapest (Hungary); Labit, B.; Chavan, R.; Duval, B. [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association EURATOM-Confédération Suisse, EPFL SB CRPP, Station 13, CH-1015 Lausanne (Switzerland)] [Ecole Polytechnique Fédérale de Lausanne (EPFL), Centre de Recherches en Physique des Plasmas, Association EURATOM-Confédération Suisse, EPFL SB CRPP, Station 13, CH-1015 Lausanne (Switzerland)

2013-12-15

77

Earth's CMB topography and mantle convection  

NASA Astrophysics Data System (ADS)

Better understanding topography on Earth's core-mantle boundary (CMB) may provide important constraints on mantle dynamics, specifically the style of mantle convection, and on lower mantle heterogeneity. For example, the origin of large, lowermost mantle low shear wave velocity provinces beneath the central Pacific and Africa is not well constrained, but are likely related to both mantle dynamics and CMB topography. Two competing hypotheses for these anomalies are: thermal upwellings (e.g., plume clusters) or large intrinsically dense piles of primitive mantle material (e.g., thermochemical piles). Here we discuss the results from our current 3D investigation of CMB topography in two styles of mantle convection: 1) an isochemical mantle with plume clusters, and 2) a thermochemical mantle with large, intrinsically dense piles. In this study, we numerically investigate 3D spherical models of mantle convection and calculate maps of topography (CMB and surface, with self-gravitation included) and geoid (CMB and surface). Maps of CMB topography and geoid (CMB and surface) are produced, and compared to observed CMB topography (e.g., Morelli and Dziewonski, 1987; Boschi and Dziewonski, 2000; Sze and van der Hilst, 2003) and surface geoid (e.g., Earth Geopotential Model, 1996). Our predicted surface geoid maps provide a key image of how CMB topography, for any given model, will affect the geoid. The results of this work emphasize the importance in using a suite of observables (in this case, topography and geoid maps for CMB and surface) to constrain whole mantle dynamics and lower mantle structure.

Lassak, T. M.; McNamara, A. K.; Zhong, S.; Garnero, E.

2008-12-01

78

Transient thermal effects below complex topographies  

NASA Astrophysics Data System (ADS)

The topographical perturbation of steady-state subsurface temperature fields has been an important issue in geothermal interpretations throughout the past century. This paper reports a numerical study, which considers the possible influence of terrain topography on transient temperature signals. Typical morphological situations over wide areas in central Europe affect most likely that same depth range which also contains the temperature signals resulting from the most interesting ground surface temperature changes (i.e. during the last 200 years). The evaluation of the interaction is performed on a synthetic sinusoidal topography with varying wavelength and amplitude. Vertical profiles (i.e. temperature logs) were extracted from these numerical forward 2-D calculations. Thereby, the error could be estimated by comparing ground surface temperature time-histories inverted from temperature logs both with and without topographic correction. The results show that a topographic correction of temperature data is absolutely necessary to achieve a consistent inversion result. Even rather flat topographies with 20-km wavelengths and 100-m amplitudes may introduce topographical effects which confuse the inversion process. On the other hand, the palaeoclimatically induced temperature signal persists even in rough topographies and will show correct inversion results when data are adequately treated. Only extreme situations cause a lateral interference of these transient signals with depth. The results from such 2-D synthetic models have been confirmed by an analysis of a real situation. The example chosen is the area surrounding the German Continental Deep Drilling (KTB) project. The area is situated in a moderately undulating surface topography with maximum altitude variations of the order of 250 m. The additional 3-D simulation demonstrates that a strong topography-dependent variation of the transient temperature signal can occur even at greater depths. The introduction of corrections for topography influence, reduces apparent differences in profiles from different locations in the surroundings of the KTB site to a maximum of 0.2 K.

Kohl, Thomas

1999-06-01

79

OpenTopography  

NASA Astrophysics Data System (ADS)

OpenTopography is a cyberinfrastructure-based facility for online access to high-resolution topography and tools. The project is an outcome of the Geosciences Network (GEON) project, which was a research project funded several years ago in the US to investigate the use of cyberinfrastructure to support research and education in the geosciences. OpenTopography provides online access to large LiDAR point cloud datasets along with services for processing these data. Users are able to generate custom DEMs by invoking DEM services provided by OpenTopography with custom parameter values. Users can track the progress of their jobs, and a private myOpenTopo area retains job information and job outputs. Data available at OpenTopography are provided by a variety of data acquisition groups under joint agreements and memoranda of understanding (MoU). These include national facilities such as the National Center for Airborne Lidar Mapping, as well as local, state, and federal agencies. OpenTopography is also being designed as a hub for high-resolution topography resources. Datasets and services available at other locations can also be registered here, providing a "one-stop shop" for such information. We will describe the OpenTopography system architecture and its current set of features, including the service-oriented architecture, a job-tracking database, and social networking features. We will also describe several design and development activities underway to archive and publish datasets using digital object identifiers (DOIs); create a more flexible and scalable high-performance environment for processing of large datasets; extend support for satellite-based and terrestrial lidar as well as synthetic aperture radar (SAR) data; and create a "pluggable" infrastructure for third-party services. OpenTopography has successfully created a facility for sharing lidar data. In the next phase, we are developing a facility that will also enable equally easy and successful sharing of services related to these data.

Baru, C.; Arrowsmith, R.; Crosby, C.; Nandigam, V.; Phan, M.; Cowart, C.

2012-04-01

80

Validation of Dynamic Contrast Enhanced Ultrasound in Rodent Kidneys as an Absolute Quantitative Method for Measuring Blood Perfusion  

PubMed Central

Contrast-enhanced ultrasound (CEUS) has demonstrated utility in the monitoring of blood flow in tissues, organs, and tumors. However, current CEUS methods typically provide only relative image-derived measurements, rather than quantitative values of blood flow in milliliters/minute per gram of tissue. In this study, CEUS derived parameters of blood flow are compared to absolute measurements of blood flow in rodent kidneys. Additionally, the effect of contrast agent infusion rate and transducer orientation on image-derived perfusion measurements are assessed. Both wash-in curve and time-to-refill algorithms are examined. Data illustrate that for all conditions, image-derived flow measurements were well-correlated with transit-time flow probe measurements (R > 0.9). However, we report differences in the sensitivity to flow across different transducer orientations as well as the contrast analysis algorithm utilized. Results also indicate that there exists a range of contrast agent flow rates for which image-derived estimates are consistent. PMID:21601135

Kogan, Paul; Johnson, Kennita A.; Feingold, Steven; Garrett, Nicholas; Guracar, Ismayil; Arendshorst, William J.; Dayton, Paul A.

2011-01-01

81

Moire topography in odontology  

NASA Astrophysics Data System (ADS)

For several decades measurement optical techniques have been used in different branches of Science and Technology and in medicine. One of these techniques is the so-called Moire topography that allows the accurate measurement of different parts of the human body topography. This investigation presents the measurement of topographies of teeth and gums using an automated system of shadow moire, with which precision can be reached up to the order of the microns by the phase shift instrumentation in an original way. Advantages and disadvantages of using the Moire topography and its comparison with other techniques used in the optical metrology are presented. Also, some positive and negative aspects of the implementation of this technique are shown in dentistry.

Moreno Yeras, A.

2001-08-01

82

Absolute quantification of cerebral blood flow in neurologically normal volunteers: dynamic-susceptibility contrast MRI-perfusion compared with computed tomography (CT)-perfusion.  

PubMed

To improve the reproducibility of arterial input function (AIF) registration and absolute cerebral blood flow (CBF) quantification in dynamic-susceptibility MRI-perfusion (MRP) at 1.5T, we rescaled the AIF by use of a venous output function (VOF). We compared CBF estimates of 20 healthy, elderly volunteers, obtained by computed tomography (CT)-perfusion (CTP) and MRP on two consecutive days. MRP, calculated without the AIF correction, did not result in any significant correlation with CTP. The rescaled MRP showed fair to moderate correlation with CTP for the central gray matter (GM) and the whole brain. Our results indicate that the method used for correction of partial volume effects (PVEs) improves MRP experiments by reducing AIF-introduced variance at 1.5T. PMID:19253361

Ziegelitz, Doerthe; Starck, Göran; Mikkelsen, Irene K; Tullberg, Mats; Edsbagge, Mikael; Wikkelsö, Carsten; Forssell-Aronson, Eva; Holtås, Stig; Knutsson, Linda

2009-07-01

83

The analysis of space-time structure in QCD vacuum II: Dynamics of polarization and absolute X-distribution  

SciTech Connect

Highlights: > We propose a method to compute the polarization for a multi-dimensional random distribution. > We apply the method to the eigenemodes of the Dirac operator in pure glue QCD. > We compute the chiral polarization for these modes and study its scale dependence. > We find that in a finite volume there is a scale where the polarization tendency changes. > We study the continuum limit of this chiral polarization scale. - Abstract: We propose a framework for quantitative evaluation of dynamical tendency for polarization in an arbitrary random variable that can be decomposed into a pair of orthogonal subspaces. The method uses measures based on comparisons of given dynamics to its counterpart with statistically independent components. The formalism of previously considered X-distributions is used to express the aforementioned comparisons, in effect putting the former approach on solid footing. Our analysis leads to the definition of a suitable correlation coefficient with clear statistical meaning. We apply the method to the dynamics induced by pure-glue lattice QCD in local left-right components of overlap Dirac eigenmodes. It is found that, in finite physical volume, there exists a non-zero physical scale in the spectrum of eigenvalues such that eigenmodes at smaller (fixed) eigenvalues exhibit convex X-distribution (positive correlation), while at larger eigenvalues the distribution is concave (negative correlation). This chiral polarization scale thus separates a regime where dynamics enhances chirality relative to statistical independence from a regime where it suppresses it, and gives an objective definition to the notion of 'low' and 'high' Dirac eigenmode. We propose to investigate whether the polarization scale remains non-zero in the infinite volume limit, in which case it would represent a new kind of low energy scale in QCD.

Alexandru, Andrei, E-mail: aalexan@gwu.edu [Department of Physics, George Washington University, Washington, DC 20052 (United States); Draper, Terrence; Horvath, Ivan [Department of Physics and Astronomy, University of Kentucky, Lexington, KY 40506 (United States); Streuer, Thomas [Department of Physics, University of Regensburg, 93040 Regensburg (Germany)

2011-08-15

84

Combining Steady-State and Dynamic Methods for Determining Absolute Signs of Hyperfine Interactions: Pulsed ENDOR Saturation and Recovery (PESTRE)  

PubMed Central

The underlying causes of asymmetric intensities in Davies pulsed ENDOR spectra that are associated with the signs of the hyperfine interaction are reinvestigated. The intensity variations in these asymmetric ENDOR patterns are best described as shifts in an apparent baseline intensity that occurs dynamically following on-resonance ENDOR transitions. We have developed an extremely straightforward multi-sequence protocol that is capable of giving the sign of the hyperfine interaction by probing a single ENDOR transition, without reference to its partner transition. This technique, Pulsed ENDOR Saturatation and Recovery (PESTRE) monitors dynamic shifts in the ‘baseline’ following measurements at a single RF frequency (single ENDOR peak), rather than observing anomalous ENDOR intensity differences between the two branches of an ENDOR response. These baseline shifts, referred to as dynamic reference levels (DRLs), can be directly tied to the electron spin manifold from which that ENDOR transition arises. The application of this protocol is demonstrated on 57Fe ENDOR of a 2Fe-2S ferredoxin. We use the 14N ENDOR transitions of the S = 3/2 [Fe(II)NO]2+ center of the non-heme iron enzyme, anthranilate dioxygenase (AntDO) to examine the details of the relaxation model using PESTRE. PMID:21075026

Doan, Peter E.

2010-01-01

85

Experimental and numerical modeling of wind flow over complex topography  

NASA Astrophysics Data System (ADS)

Wind mapping is of utmost importance in various wind engineering, wind environment, and wind energy applications. The available wind atlases usually provide wind data with low resolutions relative to the wind turbine height and size and usually neglect the effect of topographic features with relatively large or sudden changes in elevation. Developing a cost effective methodology to predict the wind patterns and to obtain wind maps over any topographic terrain is absolutely needed for wind turbine/farm siting. As the previous analytic and empirical attempts to resolve the flow over topographic features were limited to basic geometries that hardly exist in nature, applying Particle Image Velocimetry (PIV) measurement techniques in wind tunnel and Computational Fluid Dynamics (CFD) techniques in numerical simulation of the flow over topography seems to be the best alternative solution to the problem. PIV measurements and CFD simulations are carried out on a 1:3000 scale model of complex topographic area. Three distinct topographic features are investigated: a valley, a ridge and a hill. The PIV measurements compare well with hot-wire based mean velocity profiles for the three cases. Moreover, the turbulence intensity profiles match well for flow regions without recirculation. The ridge wake region shows discrepancies between the two techniques which are attributed to the complexity of the flow in this region and limitations of both techniques. A procedure incorporating Geographic Information System (GIS) and surface modeling techniques is introduced to build the CFD model of a complex terrain starting from the existing topography maps with desired resolutions. Moreover, a new approach is made to simulate the terrain roughness up to ultimate roughness heights, by implementing arrays of bell-shaped roughness elements in the CFD model. The velocity profiles and velocity vectors were compared with the PIV measurements and were found to be in good agreement near the ground and up to the full scale height of 300m. The study shows that PIV measurements and CFD simulations can be successfully used in qualifying and quantifying the flow over complex topography consisting of a wide range of roughness heights, enabling to map the flow structure with very high spatial resolution. KEYWORDS: Wind mapping, Complex topography, Computational fluid dynamics (CFD), Particle image velocimetry (PIV).

Rasouli, Ashkan

86

Moiré topography in odontology  

NASA Astrophysics Data System (ADS)

For several decades, measurement of optical techniques has been used in different branches of science and technology. One of these techniques is the so-called moiré topography (MT) that enables the accurate measurement of different parts of the human body topography. This investigation presents the measurement of topographies of teeth and gums using an automated system of shadow moiré and the phase shift method in an original way. The fringe patterns used to compute the shape and the shape matrix itself are presented in the article. The phase shift method ensures precisions up to the order of microns. Advantages and disadvantages of using the MT are included. Besides, some positive and negative aspects concerned with the implementation of this technique in odontology are shown in the article.

Moreno Yeras, A.

2003-07-01

87

Consequences of membrane topography.  

PubMed

The surface of mammalian cells is neither smooth nor flat and cells have several times more plasma membrane than the minimum area required to accommodate their shape. We discuss the biological function of this apparent excess membrane that allows the cells to migrate and undergo shape changes and probably plays a role in signal transduction. Methods for studying membrane folding and topography--atomic force microscopy, scanning ion conductance microscopy, fluorescence polarization microscopy and linear dichroism--are described and evaluated. Membrane folding and topography is frequently ignored when interpreting microscopy data. This has resulted in several misconceptions regarding for instance colocalization, membrane organization and molecular clustering. We suggest simple ways to avoid these pitfalls and invoke Occam's razor--that simple explanations are preferable to complex ones. Topography, i.e. deviations from a smooth surface, should always be ruled out as the cause of anomalous data before other explanations are presented. PMID:23438106

Parmryd, Ingela; Onfelt, Björn

2013-06-01

88

PRK in patients with a keratoconic topography picture. The concept of a physiological 'displaced apex syndrome'  

Microsoft Academic Search

AIMS\\/BACKGROUND: Keratoconus is generally held to be an absolute contraindication for photorefractive keratectomy (PRK). Corneas with inferior steepening on corneal topography are widely thought to have subclinical keratoconus. We were not convinced that this is always the case, as there seems to be a group of patients with a stable inferior steepening pattern on topography who show no other characteristics

S J Doyle; E Hynes; S Naroo; S Shah

1996-01-01

89

Topography-assisted photoablation  

NASA Astrophysics Data System (ADS)

Topography assisted photoablation (TAP) is an important and logic step for future customized therapeutic photokeratectomy. Its goal is to reshape any irregular corneal surface in order to achieve an ideal sphere. Accuracy and reproducibility of the 2D and 3D topography data, strategies of data acquisition, data modification and transfer are essential elements. Accurate and appropriate subtraction methods for difference mapping are discussed. Furthermore, the properties and algorithms of the lasers' delivery systems, have to be taken into account. The overview paper describes and discusses some of the central elements of TAP.

Jean, Benedikt J.; Bende, Thomas

1999-06-01

90

Interpretation of X-Ray topography  

Microsoft Academic Search

X-Ray topography is a powerfull method to study isolated defects in macroscopic crystals. The contrast of the most common defects is rather well-known and their study may be done without a good knowledge of the dynamical theory. Very simples rules permit to everybody the use of this method. An accurate model for the deformation due to a defect may be

Y. Epelboin; M. Curie

1980-01-01

91

Moiré topography by slit beam scanning.  

PubMed

A new method of moiré topography is suggested in which a slit beam is used in a scanning mode to generate moiré fringes. One remarkable feature of this method is that, as opposed to existing shadow and projection types, height differences between two consecutive fringes become constant so that absolute fringe orders need not be identified. This advantage makes it possible to measure three-dimensional surface profiles in an automatic manner simply by using a computer-aided image-processing technique. In addition this method can be easily implemented in a conventional coordinate measuring machine with a minimum addition of optical hardware. PMID:20733823

Kim, S W; Park, H G

1992-10-01

92

Flow Interaction with Topography  

NSDL National Science Digital Library

This is a foundation module in the Mesoscale Meteorology Primer series. Topics covered include an overview of factors that control whether air will go up and over a mountain or be forced around it, the role of potential and kinetic energy, the Froude number and what it tells you, and air flow blocked by topography.

Comet

2001-01-01

93

Flow Interaction with Topography  

NSDL National Science Digital Library

This module explores the fundamental concepts used to determine how air flow interacts with topography. Using the simple analogy of a marble rolling over a hill, this module examines the relationship between wind speed and static stability of the atmosphere. These results are further extended to include three-dimensional terrain barriers as well as the evolution through time of the interaction.

Spangler, Tim

1999-05-01

94

Phobos' shape and topography models  

NASA Astrophysics Data System (ADS)

The global shape and the dynamic environment are fundamental properties of a body. Other properties such as volume, bulk density, and models for the dynamic environment can subsequently be computed based on such models. Stereo-photogrammetric methods were applied to derive a global digital terrain model (DTM) with 100 m/pixel resolution using High Resolution Stereo Camera images of the Mars Express mission and Viking Orbiter images. In a subsequent least-squares fit, coefficients of the spherical harmonic function to degree and order 45 are computed. The dynamic models for Phobos were derived from a polyhedron representation of the DTM. The DTM, spherical harmonic function model, and dynamic models, have been refined and represent Phobos' dynamic and geometric topography with much more detail when compared to Shi et al. (2012) and Willner et al. (2010) models, respectively. The volume of Phobos has been re-determined to be in the order of 5741 km3 with an uncertainty of only 0.6% of the total volume. This reduces the bulk density to 1.86±0.013 g/cm3 in comparison to previous results. Assuming a homogeneous mass distribution a forced libration amplitude for Phobos of 1.14° is computed that is in better agreement with observations by Willner et al. (2010) than previous estimates.

Willner, K.; Shi, X.; Oberst, J.

2014-11-01

95

Crustal thickness and support of topography on Venus  

E-print Network

The topography of a terrestrial planet can be supported by several mechanisms: (1) crustal thickness variations, (2) density variations in the crust and mantle, (3) dynamic support, and (4) lithospheric stresses. Each of ...

James, Peter Benjamin

96

Gallery of Virtual Topography  

NSDL National Science Digital Library

The Gallery of Virtual Topography features virtual depictions of topography, including 3D perspectives and QuickTime Virtual Reality (QTVR) movies, created from Digital Elevation Models (DEM's). The site showcases QTVR object movies where the user can spin a 3D terrain to view it from different perspectives. It also includes static 3D-perspective images (JPEG files) of the 3D terrains for those users with slower Internet connections. Some movies and images depict only the form of the landscape, but in others topographic contours are draped over the landscape to better illustrate how contours portray different types of topography (cliffs versus badlands, for example). Some animations illustrate the significance of contours, by allowing the user to progressively fill the landscape up with water to see the water interact with different topographic features. The site also contains a topographic contour map for each 3D terrain, so that instructors can develop student exercises, such as locating points on a map and constructing topographic profiles. Some QTVR movies contain numbered topographic features just for this purpose.

Reynolds, Stephen

97

The functional topography and temporal dynamics of overlapping and distinct brain activations for adaptive task control and stable task-set maintenance during performance of an fMRI-adapted clinical continuous performance test.  

PubMed

Previous studies have demonstrated that stable and adaptive attention processes are mediated by partly overlapping, but distinct, brain areas. Dorsal medial PFC and anterior insula may form a "core network" for attention control, which is believed to operate on both temporal scales. However, both the existence of such a network as well as the unique functional topography for adaptive and stable attention processes is still highly debated. In this study, 87 healthy participants performed a clinical not-X continuous performance test optimized for use in a mixed block and event-related fMRI design. We observed overlapping activations related to stable and adaptive attention processes in dorsal medial PFC and anterior insula/adjacent cortex as well as in the right inferior parietal lobe and middle temporal gyrus. We also identified areas of activations uniquely related to stable and adaptive attention processes in widespread cortical, cerebellar, and subcortical areas. Interestingly, the functional topography within the PFC indicated a rostro-caudal distribution of adaptive, relative to stable, attention processes. There was also evidence for a time-on-task effect for activations related to stable, but not adaptive, attention processes. Our results provide further evidence for a "core network" for attention control that is accompanied by unique areas of activation involved in domain-specific processes operating on different temporal scales. In addition, our results give new insights into the functional topography of stable and adaptive attention processes and their temporal dynamics in the context of an extensively used clinical attention test. PMID:23363414

Olsen, Alexander; Ferenc Brunner, Jan; Evensen, Kari Anne Indredavik; Garzon, Benjamin; Landrø, Nils Inge; Håberg, Asta Kristine

2013-06-01

98

Absolute nuclear material assay  

DOEpatents

A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

Prasad, Manoj K. (Pleasanton, CA); Snyderman, Neal J. (Berkeley, CA); Rowland, Mark S. (Alamo, CA)

2012-05-15

99

Toward optical coherence topography  

NASA Astrophysics Data System (ADS)

Commercial OCT systems provide pachymetry measurements. Full corneal topographic information of anterior and posterior corneal surfaces for use in cataract surgery and refractive procedures is a desirable goal and would add to the usefulness of anterior and posterior segment evaluation. While substantial progress has been made towards obtaining "average" central corneal power (D Huang), power in different meridians and topography are still missing. This is usually reported to be due to eye movement. We analyze the role of centration, eye movements and develop a model that allows for the formulation of criteria for obtaining reliable topographic data within ¼ diopter.

Sayegh, Samir; Jiang, Yanshui

2012-03-01

100

Corneal topography system  

NASA Astrophysics Data System (ADS)

A new corneal topography system is described which combines proven grid projection and stereo triangulation techniques with an innovative user interface which simplifies the data capture process. Principles of the imaging, measurement, and calibration processes used with the system are presented. The device generates a complete topographic model of the anterior corneal surface with spatial resolution of 0.2 millimeters and elevation accuracy of 2 microns. System applications include pre- and post-operative assessment of refractive surgery patients, contact lens fitting including specification of custom RGP lenses, and excimer surgery planning and simulation. The innovative features of the system are described along with preliminary results of accuracy evaluations.

Cambier, James L.; Gao, Yan

1998-03-01

101

Measuring Absolute Oxygen Pressure  

NASA Technical Reports Server (NTRS)

Sensor determines absolute pressure of oxygen without reference pressure source. Absolute oxygen pressure transducer with control circuit enables measurement without reference pressure. Transducer, two part device, combines solid electrolyte membranes sensor with diffusional orifice. Device adapted for direct control of oxygen pressure in combustion mixtures.

Richter, R.

1985-01-01

102

RADAR Reveals Titan Topography  

NASA Technical Reports Server (NTRS)

The Cassini Titan RADAR Mapper is a K(sub u)-band (13.78 GHz, lambda = 2.17 cm) linear polarized RADAR instrument capable of operating in synthetic aperture (SAR), scatterometer, altimeter and radiometer modes. During the first targeted flyby of Titan on 26 October, 2004 (referred to as Ta) observations were made in all modes. Evidence for topographic relief based on the Ta altimetry and SAR data are presented here. Additional SAR and altimetry observations are planned for the T3 encounter on 15 February, 2005, but have not been carried out at this writing. Results from the T3 encounter relevant to topography will be included in our presentation. Data obtained in the Ta encounter include a SAR image swath

Kirk, R. L.; Callahan, P.; Seu, R.; Lorenz, R. D.; Paganelli, F.; Lopes, R.; Elachi, C.

2005-01-01

103

Topography of Io (color)  

NASA Technical Reports Server (NTRS)

The images used to create this color composite of Io were acquired by Galileo during its ninth orbit (C9) of Jupiter and are part of a sequence of images designed to map the topography or relief on Io and to monitor changes in the surface color due to volcanic activity. Obtaining images at low illumination angles is like taking a picture from a high altitude around sunrise or sunset. Such lighting conditions emphasize the topography of the volcanic satellite. Several mountains up to a few miles high can be seen in this view, especially near the upper right. Some of these mountains appear to be tilted crustal blocks. Most of the dark spots correspond to active volcanic centers.

North is to the top of the picture which merges images obtained with the clear, red, green, and violet filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. . The resolution is 8.3 kilometers per picture element. The image was taken on June 27, 1997 at a range of 817,000 kilometers by the solid state imaging (CCD) system on NASA's Galileo spacecraft.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

1997-01-01

104

Lake Topography and Wind Waves Determining Seasonal-Spatial Dynamics of Total Suspended Matter in Turbid Lake Taihu, China: Assessment Using Long-Term High-Resolution MERIS Data  

PubMed Central

Multiple comprehensive in situ bio-optical investigations were conducted from 2005 to 2010 and covered a large variability of total suspended matter (TSM) in Lake Taihu to calibrate and validate a TSM concentration estimation model based on Medium Resolution Imaging Spectrometer (MERIS) data. The estimation model of the TSM concentration in Lake Taihu was developed using top-of-atmosphere (TOA) radiance of MERIS image data at band 9 in combination with a regional empirical atmospheric correction model, which was strongly correlated with the in situ TSM concentration (r2?=?0.720, p<0.001, and n?=?73). The relative root mean square error (RRMSE) and mean relative error (MRE) were 36.9% and 31.6%, respectively, based on an independent validation dataset that produced reliable estimations of the TSM concentration. The developed algorithm was applied to 50 MERIS images from 2003 to 2011 to obtain a high spatial and temporal heterogeneity of TSM concentrations in Lake Taihu. Seasonally, the highest and lowest TSM concentrations were found in spring and autumn, respectively. Spatially, TSM concentrations were high in the southern part and center of the lake and low in Xukou Bay, East Lake Taihu. The lake topography, including the water depth and distance from the shore, had a significant effect on the TSM spatial distribution. A significant correlation was found between the daily average wind speed and TSM concentration (r2?=?0.685, p<0.001, and n?=?50), suggesting a critical role of wind speed in the TSM variations in Lake Taihu. In addition, a low TSM concentration was linked to the appearance of submerged aquatic vegetation (SAV). Therefore, TSM dynamics were controlled by the lake topography, wind-driven sediment resuspension and SAV distribution. PMID:24846206

Zhang, Yunlin; Shi, Kun; Liu, Xiaohan; Zhou, Yongqiang; Qin, Boqiang

2014-01-01

105

Spreading of droplet with insoluble surfactant on corrugated topography  

NASA Astrophysics Data System (ADS)

The flow of microscale fluid on a topography surface is a key to further development of MEMS, nanoscience and technology. In the present paper, a theoretical model of the droplet spreading with insoluble surfactant over corrugated topography is established with the lubrication theory, and the evolution equations of film thickness and surfactant concentration in base state and disturbance state are formulated. The droplet dynamics, the nonlinear stability based on nonmodal stability theory, and the effects of topography structure and Marangoni stress are numerically simulated with PDECOL scheme. Results show that the impact of topographical surface is strengthened apparently while the Marangoni stress driven by surfactant concentration is weakened in the mid-late stages of the spreading. The droplet radius on the topography advances faster and the lowest height of liquid/gas interface near the droplet edge reduces remarkably in the intermediate stage compared with those on the flat wall. The quantity of the wavelet similar to the topography increases gradually, with the characteristics of wavelet crest height with time exhibiting a single-hump feature. The spreading stability is enhanced under the disturbance wavenumber of 4, however, is to deteriorate and even to transform into instability when wavenumber increases further. In addition, the reductive Marangoni number, enhancive capillary number, modest Peclet number, the low height of the topography as well as small wavenumber of topography can make contributions to the evident stability of droplet spreading.

Li, Chunxi; Pei, Jianjun; Ye, Xuemin

2014-09-01

106

Absolute Biodiesel Potential Country Name  

E-print Network

Absolute Biodiesel Potential Country Name Production Cost ($/liter) Potential Biodiesel Volume,234 0% 0% #12;Absolute Biodiesel Potential Country Name Production Cost ($/liter) Potential Biodiesel;Absolute Biodiesel Potential Country Name Production Cost ($/liter) Potential Biodiesel Volume (liters

Wisconsin at Madison, University of

107

Shuttle radar topography mapper (SRTM)  

NASA Astrophysics Data System (ADS)

The use of interferometric SAR (IFSAR) to measure elevation is one of the most powerful and promising capabilities of radar. A properly equipped spaceborne IFSAR system can produce a highly accurate global digital elevation map, including cloud-covered areas, in significantly less time and at significantly lower cost than with other systems. For accurate topography, the interferometric measurements must be performed simultaneously in physically sperate receive system, since measurements made at different times with the same system suffer significant decorrelation. The US/German/Italian spaceborne imaging radar C/X-band SAR (SIR-C/X-SAR), successfully flown twice in 1994 aboard the Space Shuttle Endeavor, offers a unique opportunity for global multifrequency elevation mapping by the year 2000. With appropriate augmentation, SIR-C/X-SAR is capable of producing an accurate elevation map covering 80 percent of the Earth's land surface in a single 10-day Shuttle flight. The existing US SIR-C SCANSAR mode provides a 225-km swath at C-band, which makes this coverage possible. Addition of a C-band receive antenna, extended from the Shuttle bay on a mast and operating in concert with the existing SIR-C antenna, produces an interferometric pair. Accuracy is enhanced by utilizing the SIR-C dual polarizations simultaneously to form separate SCANSAR beams. Due to the practical limitation of approximately 60 meters for the mast length, the longer SIR-C L-band wavelength does not produce useful elevation measurement accuracy. IFSAR measurements can also be obtained by the German/Italian X-SAR, simultaneously with SIR-C, by utilizing an added outboard antenna at X-band to produce a swath coverage of about 50 km. Accuracy can be enhanced at both frequencies by processing both ascending and descending data takes. It is estimated that the 90 percent linear absolute elevation error achievable is less that 16 meters for elevation postings of 30 meters. This will be the first use of spaceborne IFSAR to acquire accurate topographic data on a global scale.

Jordan, Rolando L.; Caro, Edward R.; Kim, Yunjin; Kobrick, Michael; Shen, Yuhsyen; Stuhr, Frederick V.; Werner, Marian U.

1996-12-01

108

Computing Solar Absolute Fluxes  

E-print Network

Computed color indices and spectral shapes for individual stars are routinely compared with observations for essentially all spectral types, but absolute fluxes are rarely tested. We can confront observed irradiances with the predictions from model atmospheres for a few stars with accurate angular diameter measurements, notably the Sun. Previous calculations have been hampered by inconsistencies and the use of outdated atomic data and abundances. I provide here a progress report on our current efforts to compute absolute fluxes for solar model photospheres. Uncertainties in the solar composition constitute a significant source of error in computing solar radiative fluxes.

Carlos Allende Prieto

2007-09-14

109

The length-scaling properties of topography  

NASA Technical Reports Server (NTRS)

The scaling properties of synthetic topographic surfaces and digital elevation models (DEMs) of topography are examined by analyzing their 'structure functions,' i.e., the qth order powers of the absolute elevation differences: delta h(sub q) (l) = E((absolute value of h(x + l) - h(x))(exp q)). We find that the relation delta h(sub 1 l) approximately equal cl(exp H) describes well the scaling behavior of natural topographic surfaces, as represented by DEMs gridded at 3 arc sec. Average values of the scaling exponent H between approximately 0.5 and 0.7 characterize DEMs from Ethiopia, Saudi Arabia, and Somalia over 3 orders of magnitude range in length scale l (approximately 0.1-150 km). Differences in appparent topographic roughness among the three areas most likely reflect differences in the amplitude factor c. Separate determination of scaling properties in the x and y coordinate directions allows us to assess whether scaling exponents are azimuthally dependent (anisotropic) or whether they are isotropic while the surface itself is anisotropic over a restricted range of length scale. We explore ways to determine whether topographic surfaces are characterized by simple or multiscaling properties.

Weissel, Jeffrey K.; Pratson, Lincoln F.; Malinverno, Alberto

1994-01-01

110

Synchrotron X-ray topography  

Microsoft Academic Search

The various techniques of X-ray diffraction topography image imperfections in single-crystals by Bragg reflexion, with a spatial resolution of approximately one micrometre. Defects can be studied in relation to crystal growth and physical properties. X-ray interference effects can also be explored in perfect, and nearly perfect, crystals. Synchrotron radiation has given X-ray topography additional powers, including the rapid non-destructive assessment

Moreton Moore

1995-01-01

111

Relative and Absolute Directions  

NSDL National Science Digital Library

The purpose of this resource is to learn about latitude and longitude while developing math skills. Students begin by asking the simple question: 'Where Am I?' Then they learn about the magnetic Earth and the use of compasses and angles. Students also learn about the difference between relative and absolute locations. Throughout this activity, students practice using a variety of math skills.

The GLOBE Program, University Corporation for Atmospheric Research (UCAR)

2003-08-01

112

ABSOLUTE WAARHEID EN TRANSCENDENTIE  

Microsoft Academic Search

The debate about the relation between science and truth is manifestly epistemological, but latently and fundamentally metaphysical. Popper's theory of verisimilitude provides us with a striking example. According to Popper, science aims at bringing us nearer to 'absolute, objective truth'; the growth of scientific knowledge is seen as a never ending realisation of that ultimate aim. This thesis of verisimilitude

A. BURMS

1982-01-01

113

Absolute ultraviolet stellar fluxes  

NASA Technical Reports Server (NTRS)

A study, made to calibrate the ultraviolet spectra of stars to within an absolute accuracy of 10%, is summarized. Data were taken by a 13 inch UVR telescope onboard several rocket flights. Calibrated and existing ground based data are in reasonable agreement. Calibrated results are presented in graphical form.

Evans, D. C.

1972-01-01

114

Satellite remote sensing of landscape freeze/thaw state dynamics for complex Topography and Fire Disturbance Areas Using multi-sensor radar and SRTM digital elevation models  

NASA Technical Reports Server (NTRS)

We characterize differences in radar-derived freeze/thaw state, examining transitions over complex terrain and landscape disturbance regimes. In areas of complex terrain, we explore freezekhaw dynamics related to elevation, slope aspect and varying landcover. In the burned regions, we explore the timing of seasonal freeze/thaw transition as related to the recovering landscape, relative to that of a nearby control site. We apply in situ biophysical measurements, including flux tower measurements to validate and interpret the remotely sensed parameters. A multi-scale analysis is performed relating high-resolution SAR backscatter and moderate resolution scatterometer measurements to assess trade-offs in spatial and temporal resolution in the remotely sensed fields.

Podest, Erika; McDonald, Kyle; Kimball, John; Randerson, James

2003-01-01

115

Asymmetric three-dimensional topography over mantle plumes  

NASA Astrophysics Data System (ADS)

The role of mantle-lithosphere interactions in shaping surface topography has long been debated. In general, it is supposed that mantle plumes and vertical mantle flows result in axisymmetric, long-wavelength topography, which strongly differs from the generally asymmetric short-wavelength topography created by intraplate tectonic forces. However, identification of mantle-induced topography is difficult, especially in the continents. It can be argued therefore that complex brittle-ductile rheology and stratification of the continental lithosphere result in short-wavelength modulation and localization of deformation induced by mantle flow. This deformation should also be affected by far-field stresses and, hence, interplay with the `tectonic' topography (for example, in the `active/passive' rifting scenario). Testing these ideas requires fully coupled three-dimensional numerical modelling of mantle-lithosphere interactions, which so far has not been possible owing to the conceptual and technical limitations of earlier approaches. Here we present new, ultra-high-resolution, three-dimensional numerical experiments on topography over mantle plumes, incorporating a weakly pre-stressed (ultra-slow spreading), rheologically realistic lithosphere. The results show complex surface evolution, which is very different from the smooth, radially symmetric patterns usually assumed as the canonical surface signature of mantle upwellings. In particular, the topography exhibits strongly asymmetric, small-scale, three-dimensional features, which include narrow and wide rifts, flexural flank uplifts and fault structures. This suggests a dominant role for continental rheological structure and intra-plate stresses in controlling dynamic topography, mantle-lithosphere interactions, and continental break-up processes above mantle plumes.

Burov, Evgueni; Gerya, Taras

2014-09-01

116

Absolute beam brightness detector  

SciTech Connect

In generally accepted emittance measurement, main attention is concentrated on emittance areas {epsilon}{sub x}, {epsilon}{sub y} occupied by desired part of ion beam in transverse phase space and shape of these areas. The absolute beam phase density (brightness) as usually is not measured directly and the average beam brightness B is calculated from a beam intensity I and the transverse emittances. In the ion source and low energy beam transport (LEBT) optimization, it is important to preserve the beam brightness because some aberration of ion optic and beam instabilities can decrease the brightness of the central part of ion beam significantly. For these brightness measurements, it is convenient to use an absolute beam brightness detector with the brightness determination from one short considered in this article.

Dudnikov, Vadim [Muons, Inc., Batavia, Illinois 60510 (United States)

2012-02-15

117

Supernova Absolute Magnitude Distributions  

Microsoft Academic Search

We have extended the 1990 study of supernova absolute-magnitude distributions by Miller and Branch. Supernova apparent magnitudes are taken from an updated version of the Asiago Supernova Catalog. Where possible, distances are based on Cepheid variables in the SN parent galaxy or a galaxy in the same group; otherwise re-scaled distances from the Nearby Galaxies Catalog, or Hubble-Law distances (for

D. Richardson; D. Branch; D. Casebeer; J. Deaton; E. Baron

1996-01-01

118

Deep versus shallow origin of gravity anomalies, topography and volcanism on Earth, Venus and Mars  

E-print Network

Deep versus shallow origin of gravity anomalies, topography and volcanism on Earth, Venus and Mars Available online xxxx Keywords: Earth Venus, Interior Mars, Interior Volcanism a b s t r a c t The relation dynamics of planets. From the power spectra of gravity and topography on Earth, Venus and Mars we infer

Steinberger, Bernhard

119

Amplitude of the core–mantle boundary topography estimated by stochastic analysis of core phases  

Microsoft Academic Search

The core–mantle boundary (CMB) topography is an important parameter for constraining the models of mantle dynamics and core–mantle coupling. However, the various large wavelength seismological models of the CMB topography, which have been obtained up to now, are poorly correlated. Moreover, their maximum amplitudes vary considerably from one model to another, with values ranging from ±4 to ±12 km. These

R. Garcia; A. Souriau

2000-01-01

120

Absolute configuration of odorine  

PubMed Central

The title compound, known as odorine or roxburghiline {systematic name: (S)-N-[(R)-1-cinnamoylpyrrolidin-2-yl]-2-methyl­butanamide}, C18H24N2O2, is a nitro­genous compound isolated from the leaves of Aglaia odorata. The absolute configuration was determined by refinement of the Flack parameter with data collected using Cu K? radiation showing positions 2 and 2? to be S and R, respectively. The pyrrolidine ring adopts an envelope conformation. In the crystal, mol­ecules are linked into chains along [010] by inter­molecular N—H?O hydrogen bonds. PMID:21588760

Fun, Hoong-Kun; Chantrapromma, Suchada; Yodsaoue, Orapun; Karalai, Chatchanok

2010-01-01

121

Signalling problem in absolutely unstable systems  

NASA Astrophysics Data System (ADS)

The dynamics of unstable systems crucially depends on the nature of the instability, either convective or absolute. The signalling problem, which is the study of the spatial response to a localized time-harmonic forcing, is generally believed to be relevant only for stable or convectively unstable systems and to be ill-posed for absolutely unstable systems, where the self-sustained perturbations grow faster than the forced harmonic response. The present investigation shows that the signalling problem may still be well posed for media displaying absolutely unstable regions. Considering weakly spatially inhomogenous systems, conditions are derived for the validity of the signalling problem. The complete spatial response to harmonic forcing is first analytically derived in terms of asymptotic approximations and then confirmed by direct numerical simulations.

Pier, Benoît

2011-06-01

122

Noninvasive measurement of corneal topography  

Microsoft Academic Search

The authors present a brief overview of the surface to be measured (the cornea of the eye), review the current state of the technology designed to measure the corneal topography, and define the outstanding issues of current significance. The topics discussed include: eye movements; fundamental operating principles of new systems; videokeratographic systems; fundamental limitations of the operating principles; limitations of

R. A. Applegate; H. C. Howland

1995-01-01

123

Reactions of cells to topography  

Microsoft Academic Search

Though contact guidance has been known since the very early days of cell culture very little quantitative examination of the reaction of cells to topography has been made. Exceptions to this subjective approach are given prominence below. Yet if we are to understand how cells react and if we are to be able to design ideal substrata for particular cells

Adam S. G. Curtis; Chris D. W. Wilkinson

1998-01-01

124

Absolute-structure reports.  

PubMed

All the 139 noncentrosymmetric crystal structures published in Acta Crystallographica Section C between January 2011 and November 2012 inclusive have been used as the basis of a detailed study of the reporting of absolute structure. These structure determinations cover a wide range of space groups, chemical composition and resonant-scattering contribution. Defining A and D as the average and difference of the intensities of Friedel opposites, their level of fit has been examined using 2AD and selected-D plots. It was found, regardless of the expected resonant-scattering contribution to Friedel opposites, that the Friedel-difference intensities are often dominated by random uncertainty and systematic error. An analysis of data collection strategy is provided. It is found that crystal-structure determinations resulting in a Flack parameter close to 0.5 may not necessarily be from crystals twinned by inversion. Friedifstat is shown to be a robust estimator of the resonant-scattering contribution to Friedel opposites, very little affected by the particular space group of a structure nor by the occupation of special positions. There is considerable confusion in the text of papers presenting achiral noncentrosymmetric crystal structures. Recommendations are provided for the optimal way of treating noncentrosymmetric crystal structures for which the experimenter has no interest in determining the absolute structure. PMID:23907862

Flack, Howard D

2013-08-01

125

The information as Absolute  

E-print Network

This article presents and grounds (i.e. presents proof of the existence, the truth, the self-consistence and the completeness of)the informational conception ("the Information as Absolute" conception)in physics and philosophy. the conception defines the information as an ultimately common, real and fundamental concept/phenomenon - "Absolute", which exists as anabsolutely infinite set ("Information" Set) of elements (members) and informational (e.g., logical) linksbetween the elements; where any element itself is some informational structure also. Correspondingly, for example, Matter as the substence, radiation, etc., is some development or realization of informational patterns, constituting a specific - and practically infinitesimal comparing to the Set - subset of the "Information" Set. The conception allows for the resolution, or at least for a consideration on a higher level of comprehension, of the basic ontological and epistemological problems in philosophy and natural sciences; in physics it allows to suggest reasonable model, which makes more clear basic phisical notions,such as space, time, matter, etc.

Sergey V. Shevchenko; Vladimir V. Tokarevsky

2010-04-20

126

ABSOLUTE POLARIMETRY AT RHIC.  

SciTech Connect

Precise and absolute beam polarization measurements are critical for the RHIC spin physics program. Because all experimental spin-dependent results are normalized by beam polarization, the normalization uncertainty contributes directly to final physics uncertainties. We aimed to perform the beam polarization measurement to an accuracy Of {Delta}P{sub beam}/P{sub beam} < 5%. The absolute polarimeter consists of Polarized Atomic Hydrogen Gas Jet Target and left-right pairs of silicon strip detectors and was installed in the RHIC-ring in 2004. This system features proton-proton elastic scattering in the Coulomb nuclear interference (CNI) region. Precise measurements of the analyzing power A{sub N} of this process has allowed us to achieve {Delta}P{sub beam}/P{sub beam} = 4.2% in 2005 for the first long spin-physics run. In this report, we describe the entire set up and performance of the system. The procedure of beam polarization measurement and analysis results from 2004-2005 are described. Physics topics of AN in the CNI region (four-momentum transfer squared 0.001 < -t < 0.032 (GeV/c){sup 2}) are also discussed. We point out the current issues and expected optimum accuracy in 2006 and the future.

OKADA; BRAVAR, A.; BUNCE, G.; GILL, R.; HUANG, H.; MAKDISI, Y.; NASS, A.; WOOD, J.; ZELENSKI, Z.; ET AL.

2007-09-10

127

Dynamic Surface Topography And Its Application To  

E-print Network

. The progression of the disease occurs in three dimensions with the spine simultaneously curving towards the arms and rotating as it collapses with the first indications usually being changes in body symmetry and back surface shape. Following diagnosis, most children do not exhibit any significant worsening of their condition

Torr, Philip H. S.

128

Absolute radiometric code (ARC)  

NASA Astrophysics Data System (ADS)

The Absolute Radiometric Code (ARC) is a collection of Matlab functions tied together under a Matlab Graphical User Interface (GUI). ARC was developed as part of the Satellite Imaging Experiment conducted by the Air Force Research Laboratory at Kirtland, AFB, in order to get fast estimates of the Optical Cross Sections of various satellites. ARC uses multiple star measures to calculate the atmospheric and optical transmission of the system. The transmissions are then used to compute the optical cross section of an object. Generally, the optical transmission of a sensor system can be characterized quite well, so it serves as a sanity check on all ARC results. The atmospheric transmission changes considerably from night to night and even from hour to hour on the same night. ARC uses a collection of calibration stars at various elevation angles to determine the atmospheric transmission through the viewing times. The star calibration is generally taken several times during the experiment period.

Riker, James F.; Roark, Jon; Stogsdill, Stephen E.; DeShetler, W. Bruce; Brunson, Richard L.

1999-08-01

129

Absolute Equilibrium Entropy  

NASA Technical Reports Server (NTRS)

The entropy associated with absolute equilibrium ensemble theories of ideal, homogeneous, fluid and magneto-fluid turbulence is discussed and the three-dimensional fluid case is examined in detail. A sigma-function is defined, whose minimum value with respect to global parameters is the entropy. A comparison is made between the use of global functions sigma and phase functions H (associated with the development of various H-theorems of ideal turbulence). It is shown that the two approaches are complimentary though conceptually different: H-theorems show that an isolated system tends to equilibrium while sigma-functions allow the demonstration that entropy never decreases when two previously isolated systems are combined. This provides a more complete picture of entropy in the statistical mechanics of ideal fluids.

Shebalin, John V.

1997-01-01

130

Optical tweezers absolute calibration  

E-print Network

Optical tweezers are highly versatile laser traps for neutral microparticles, with fundamental applications in physics and in single molecule cell biology. Force measurements are performed by converting the stiffness response to displacement of trapped transparent microspheres, employed as force transducers. Usually, calibration is indirect, by comparison with fluid drag forces. This can lead to discrepancies by sizable factors. Progress achieved in a program aiming at absolute calibration, conducted over the past fifteen years, is briefly reviewed. Here we overcome its last major obstacle, a theoretical overestimation of the peak stiffness, within the most employed range for applications, and we perform experimental validation. The discrepancy is traced to the effect of primary aberrations of the optical system, which are now included in the theory. All required experimental parameters are readily accessible. Astigmatism, the dominant effect, is measured by analyzing reflected images of the focused laser spo...

Dutra, R S; Neto, P A Maia; Nussenzveig, H M

2014-01-01

131

Whitebeam X-ray topography  

Microsoft Academic Search

After radiography, white-beam X-ray topography (XRT) is the simplest X-ray imaging technique for crystals. An X-ray topograph is formed by a Bragg reflexion and is in effect a high-spatial-resolution Laue ‘spot’. Synchrotron radiation has given XRT additional powers, with its broad continuous spectrum, small beam divergence, high intensity, strong polarization and regular pulsed time structure. Each Laue image, however, may

Moreton Moore

2012-01-01

132

Topography, Cell Response, and Nerve Regeneration  

PubMed Central

In the body, cells encounter a complex milieu of signals, including topographical cues. Imposed topography can affect cells on surfaces by promoting adhesion, spreading, alignment, morphological changes, and changes in gene expression. Neural response to topography is complex, and depends on the dimensions and shapes of physical features. Looking toward repair of nerve injuries, strategies are being explored to engineer guidance conduits with precise surface topographies. How neurons and other cell types sense and interpret topography remains to be fully elucidated. Studies reviewed here include those of topography on cellular organization and function as well as potential cellular mechanisms of response. PMID:20438370

Hoffman-Kim, Diane; Mitchel, Jennifer A.; Bellamkonda, Ravi V.

2010-01-01

133

The Role of Topography in Glacial Inception  

NASA Astrophysics Data System (ADS)

We test the influence of model topography on glacial inception using a coupled atmosphere-slab ocean version of NCAR’s Community Climate System Model (CCSM3). Simulations employ a modern orbital configuration and greenhouse gas concentrations representing both recent (year 1990) and hypothetically lower present-day values in accordance with Ruddiman’s Early Anthropogenic Hypothesis (240 ppm CO2 and 450 ppb CH4). The model is run at two different resolutions: a relatively coarse horizontal configuration (T42, approximately 2.8 degrees) and comparatively fine resolution (T85, approximately 1.4 degrees). Although under contemporary greenhouse forcing the extent of permanent boreal snow cover in the two model configurations is similar, imposing lower concentrations of CO2 and CH4 generates much more extensive glacial inception in the T85 experiment (150% increase) than in the T42 version (80% increase). Furthermore, the spatial patterns of glacial inception differ considerably. Only the T85 resolution produces widespread permanent snow cover over the Rocky Mountains and on Baffin Island, consistent with geologic evidence for ice sheet nucleation in northeastern Canada. Although much of the enhanced sensitivity in the higher-resolution simulations is directly attributable to the colder and wetter conditions around elevated topography, some of the response also appears to be driven dynamically and remotely as a function of the simulated elevation of Greenland. The colder conditions over and downstream of the Greenland Ice Sheet in the modern T85 simulation promote a smaller cooling locally under lowered greenhouse forcing that seems to activate a wave-1 dynamical response in the atmospheric pressure field. The resulting circulation anomalies favor stronger upslope wind flow from the Pacific Ocean over the northern Rocky Mountains, enhancing the regional development of a permanent snow pack. Although these experiments are driven by greenhouse forcing rather than historical orbital variations, we believe that our findings apply to the general mechanisms of glacial inception.

Vavrus, S. J.; Philippon-Berthier, G.; Kutzbach, J. E.; Ruddiman, W. F.

2009-12-01

134

Absolute neutrino mass measurements  

SciTech Connect

The neutrino mass plays an important role in particle physics, astrophysics and cosmology. In recent years the detection of neutrino flavour oscillations proved that neutrinos carry mass. However, oscillation experiments are only sensitive to the mass-squared difference of the mass eigenvalues. In contrast to cosmological observations and neutrino-less double beta decay (0v2{beta}) searches, single {beta}-decay experiments provide a direct, model-independent way to determine the absolute neutrino mass by measuring the energy spectrum of decay electrons at the endpoint region with high accuracy.Currently the best kinematic upper limits on the neutrino mass of 2.2eV have been set by two experiments in Mainz and Troitsk, using tritium as beta emitter. The next generation tritium {beta}-experiment KATRIN is currently under construction in Karlsruhe/Germany by an international collaboration. KATRIN intends to improve the sensitivity by one order of magnitude to 0.2eV. The investigation of a second isotope ({sup 137}Rh) is being pursued by the international MARE collaboration using micro-calorimeters to measure the beta spectrum. The technology needed to reach 0.2eV sensitivity is still in the R and D phase. This paper reviews the present status of neutrino-mass measurements with cosmological data, 0v2{beta} decay and single {beta}-decay.

Wolf, Joachim [Karlsruhe Institute of Technology (KIT), IEKP, Postfach 3640, 76021 Karlsruhe (Germany)

2011-10-06

135

Absolute Zero: Science Educator's Guide  

NSDL National Science Digital Library

This guide provides recommendations for curricular modules on low temperature physics. Designed for teachers and informal educators of middle school students. this guide complements the Absolute Zero Community Education Outreach Guide. Suggestions on leading discussions, increasing student participation, and the use of inquiry are included. This material is related to a two-part public broadcasting special, Absolute Zero, produced by Meridian Productions and Windfall Films. Absolute Zero is underwritten by the National Science Foundation and the Alfred P. Sloan Foundation and is based largely on Tom Shachtmanâs acclaimed book, Absolute Zero and the Conquest of Cold.

2008-09-18

136

Supernova absolute-magnitude distributions  

Microsoft Academic Search

The Asiago Supernova Catalogue and the Nearby Galaxies Catalog are used to study the absolute-magnitude distributions of supernovae. SNe Ia that appear to be subluminous are in highly inclined disk galaxies, which implies that the apparent dispersion in SN Ia absolute magnitudes is dominated by interstellar extinction in the parent galaxies, and, thus, that SNe Ia are good intrinsic standard

Douglas L. Miller; David Branch

1990-01-01

137

Absolute and Relative Grading Standards.  

ERIC Educational Resources Information Center

K. K. Waltman and D. A. Frisbie (1994) observed that teachers and parents often interpret grades given to students in both absolute and relative senses. They conclude that this sort of interpretation is illogical and may indicate misunderstandings in several areas. Absolute and relative methods of assigning letter grades are approached from…

Johanson, George A.

138

Plasma processing for nanostructured topographies  

NASA Astrophysics Data System (ADS)

Plasma and directed ion interactions with materials have been widely observed to create complex surface patterns on a micro- and nano- scale. Generally, these texturizations are byproducts of another intended application (such as a feature formation on a sputtering target) and patterning is considered inconsequential or even detrimental. This work examined the possibility of using these phenomena as primary methods for producing beneficial topographies. Specifically, investigations focused on the use of helium plasma exposure and directed ion etching to create nanostructured surfaces capable of affecting biological interactions with implanted materials. Orthogonal argon ion etching and low energy helium plasma texturization of titanium were considered for use on orthopedic and dental implants as a means of increasing osteoblast activity and bone attachment; and oblique angle etching was evaluated for its use in creating topographies with cell deterrent or anti-thrombogenic properties. In addition, the helium driven evolution of surface features on 6061 aluminum alloy was characterized with respect to ion energy and substrate temperature. These surfaces were then considered for ice phobic applications.

Riedel, Nicholas Alfred

139

Quantifying turbidity current interactions with topography  

E-print Network

This thesis advances our understanding of how transport properties of turbidity currents are mediated by interactions with seafloor topography, specifically channelized surfaces. Turbidity currents are responsible for ...

Straub, Kyle M

2007-01-01

140

Transition to Absolute Instability for (not so) Dummies  

E-print Network

These notes are intended as an elementary introduction to the concept of absolute instability. The transition from convective instability to absolute instability is an important issue when the stability of stationary flow solutions is investigated. The arguments here described were first developed in the framework of plasma physics and later applied to the hydrodynamics of mixing layers and shear flows. Far from being a comprehensive analysis of this complicated subject, the aim of these notes is just to sketch a rudimentary and quite elementary ground for physicists or engineers which have a familiarity with the basic features of linear stability in fluid dynamics, but are new to the concept of absolute instability.

Barletta, Antonio

2014-01-01

141

Absolute stereochemistry of anisodorin 5  

Microsoft Academic Search

The absolute stereochemistry of the natural diterpene anisodorin 5 1, previously isolated from the marine dorid nudibranch Anisodoris fontaini, has been established by synthesis of its enantiomer ent-anisodorin 5 3.

Nicon Ungur; Margherita Gavagnin; Ernesto Mollo; Guido Cimino

1999-01-01

142

Tidal Conversion by Rough Topography  

NASA Astrophysics Data System (ADS)

The barotropic tide generates internal gravity waves due to sea floor topography, which leads to conversion of tidal energy into smaller scale waves and eventually dissipation. New measurements indicate that the tidal dissipation in the open ocean is substantially higher than predicted by theoretical models. Hence, the search is on for an effect that enhances the energy conversion rate. Using functional equations techniques, one can show that the solution for a steep triangular seamount is exactly equivalent to a triangular seamount with a slope at the angle of wave propagation. The stream function develops spatial discontinuities (shocks) as the maximum topographic slope approaches the critical slope from below. Nonlinear effects become important in a vortex forming above the seamount, which may cause significant changes in the conversion rate.

Schorghofer, Norbert; Khatiwala, Samar; Aharonson, Oded

2003-03-01

143

Cryogenic, Absolute, High Pressure Sensor  

NASA Technical Reports Server (NTRS)

A pressure sensor is provided for cryogenic, high pressure applications. A highly doped silicon piezoresistive pressure sensor is bonded to a silicon substrate in an absolute pressure sensing configuration. The absolute pressure sensor is bonded to an aluminum nitride substrate. Aluminum nitride has appropriate coefficient of thermal expansion for use with highly doped silicon at cryogenic temperatures. A group of sensors, either two sensors on two substrates or four sensors on a single substrate are packaged in a pressure vessel.

Chapman, John J. (Inventor); Shams. Qamar A. (Inventor); Powers, William T. (Inventor)

2001-01-01

144

Mercury's global shape and topography from MESSENGER limb images  

NASA Astrophysics Data System (ADS)

We derive models for the global shape and topography of Mercury from limb images obtained by the MESSENGER spacecraft during flybys and from orbit. Crossover heights of 225 individual limb profiles were adjusted by least-squares techniques to establish a rigid global topographic network. Mercury is confirmed to possess an equatorial ellipticity and a polar oblateness. Several large impact basins and craters can be identified in the topographic model, including one basin that was earlier proposed but unconfirmed. Comparisons with absolute height data from laser altimetry indicate that the limb model appears to overestimate planetary radius by ~900 m on average. Limb profiles and local digital terrain models derived from stereo-photogrammetry show good agreement.

Elgner, Stephan; Stark, Alexander; Oberst, Jürgen; Perry, Mark E.; Zuber, Maria T.; Robinson, Mark S.; Solomon, Sean C.

2014-11-01

145

Noise-Sustained currents in quasigeostrophic turbulence over topography  

E-print Network

We study the development of mean structures in a nonlinear model of large scale ocean dynamics with bottom topography and dissipation, and forced with a noise term. We show that the presence of noise in this nonlinear model leads to persistent average currents directed along isobaths. At variance with previous works we use a scale unselective dissipation, so that the phenomenon can not be explained in terms of minimum enstrophy states. The effect requires the presence of both the nonlinear and the random terms, and can be though of as an ordering of the stochastic energy input by the combined effect of nonlinearity and topography. The statistically steady state is well described by a generalized canonical equilibrium with mean energy and enstrophy determined by a balance between random forcing and dissipation. This result allows predicting the strengh of the noise-sustained currents. Finally we discuss the relevance that these noise-induced currents could have on real ocean circulation.

Alberto Alvarez; Emilio Hernandez-Garcia; Joaquin Tintore

1997-01-09

146

Moho depth and residual topography of the Antarctic continent  

NASA Astrophysics Data System (ADS)

A new Moho depth map for the Antarctic continent has been recently assembled (ANTMoho), merging information retrieved from geophysical and geological studies selected from the literature. A large volume of old and new data have been analyzed: from active seismic prospection,including DSS profiles acquired by Soviet Union field experiments, to recent passive seismic receiver function and geological studies. ANTMoho has a reference lateral resolution of 1 degree. The oldest Archean and Proterozoic crust of East Antarctica has a thickness of 36-56 km (with an average of about 41 km). The continental crust of the Transantarctic Mountains, the Antarctic Peninsula and Wilkes Basin has a thickness of 30-40 km (with an average Moho of about 30 km). The youngest rifted continental crust of the West Antarctic Rift System has a thickness of 16-28 km (with an average Moho of about 26 km). The mean Moho depth of the whole model is 33.8 km. We compare this new model to other available for the whole continent (Bassin et al., 2000; Block et al., 2009) and study the possible geodynamic consequences calculating the residual topography -- an indicator of dynamic response to large-scale mantle flow. We adopt the semianalytical methodology implemented in the HC code (developed and maintained by Prof. T. Becker). The spatial resolution is limited by the L=127 of the input model. The Transantarctic Mountains appear not to be isostatically compensated, such as the neighboring Wilkes Subglacial Basin. East Antarctica on a large scale does not show significant uncompensated topography. There are however some smaller-scale residual topography features, that correlate with sub-glacial topography and that may indicate some limitation in resolution or laterally-variable crustal density. Better knowledge of crustal structure is therefore an important tool for better understanding of the complex dynamic processes acting at a regional scale.

Baranov, Alexey; Molinari, Irene; Morelli, Andrea; Danesi, Stefania

2013-04-01

147

Topography and Landforms of Ecuador  

USGS Publications Warehouse

EXPLANATION The digital elevation model of Ecuador represented in this data set was produced from over 40 individual tiles of elevation data from the Shuttle Radar Topography Mission (SRTM). Each tile was downloaded, converted from its native Height file format (.hgt), and imported into a geographic information system (GIS) for additional processing. Processing of the data included data gap filling, mosaicking, and re-projection of the tiles to form one single seamless digital elevation model. For 11 days in February of 2000, NASA, the National Geospatial-Intelligence Agency (NGA), the German Aerospace Center (DLR), and the Italian Space Agency (ASI) flew X-band and C-band radar interferometry onboard the Space Shuttle Endeavor. The mission covered the Earth between 60?N and 57?S and will provide interferometric digital elevation models (DEMs) of approximately 80% of the Earth's land mass when processing is complete. The radar-pointing angle was approximately 55? at scene center. Ascending and descending orbital passes generated multiple interferometric data scenes for nearly all areas. Up to eight passes of data were merged to form the final processed SRTM DEMs. The effect of merging scenes averages elevation values recorded in coincident scenes and reduces, but does not completely eliminate, the amount of area with layover and terrain shadow effects. The most significant form of data processing for the Ecuador DEM was gap-filling areas where the SRTM data contained a data void. These void areas are a result of radar shadow, layover, standing water, and other effects of terrain, as well as technical radar interferometry phase unwrapping issues. To fill these gaps, topographic contours were digitized from 1:50,000 - scale topographic maps which date from the mid-late 1980's (Souris, 2001). Digital contours were gridded to form elevation models for void areas and subsequently were merged with the SRTM data through GIS and remote sensing image-processing techniques. The data contained in this publication includes a gap filled, countrywide SRTM DEM of Ecuador projected in Universal Transverse Mercator (UTM) Zone 17 North projection, Provisional South American, 1956, Ecuador datum and a non gap filled SRTM DEM of the Galapagos Islands projected in UTM Zone 15 North projection. Both the Ecuador and Galapagos Islands DEMs are available as an ESRI Grid, stored as ArcInfo Export files (.e00), and in Erdas Imagine (IMG) file formats with a 90 meter pixel resolution. Also included in this publication are high and low resolution Adobe Acrobat (PDF) files of topography and landforms maps in Ecuador. The high resolution map should be used for printing and display, while the lower resolution map can be used for quick viewing and reference purposes.

Chirico, Peter G.; Warner, Michael B.

2005-01-01

148

Supernova absolute-magnitude distributions  

SciTech Connect

The Asiago Supernova Catalogue and the Nearby Galaxies Catalog are used to study the absolute-magnitude distributions of supernovae. SNe Ia that appear to be subluminous are in highly inclined disk galaxies, which implies that the apparent dispersion in SN Ia absolute magnitudes is dominated by interstellar extinction in the parent galaxies, and, thus, that SNe Ia are good intrinsic standard candles (sigma below 0.4 mag). An upper limit to the difference between SNe Ib and SNe Ia in the B band is 1.87 mag, but the bolometric difference is smaller. Due to a large intrinsic range in peak absolute magnitude (about 6 mag), the observed sample of SNe II is severely influenced by selection effects; intrinsically faint SNe II (M/B/greater than about -17 for H0 = 75 km/s per Mpc) are much more common than intrinsically bright ones. 45 refs.

Miller, D.L.; Branch, D. (Oklahoma Univ., Norman (USA))

1990-08-01

149

Absolute configuration of amphidinin A.  

PubMed

The absolute configurations at six stereogenic centers in amphidinin A (1), a cytotoxic linear polyketide isolated from a symbiotic marine dinoflagellate, Amphidinium sp., were elucidated to be 2R, 4R, 6S, 9R 11R, and 12S by the combination of J-based configuration analysis, modified Mosher's method, and density-functional theory calculations. PMID:24836179

Iwai, Takahiro; Kubota, Takaaki; Kobayashi, Jun'ichi

2014-06-27

150

Absolute transition probabilities of phosphorus.  

NASA Technical Reports Server (NTRS)

Use of a gas-driven shock tube to measure the absolute strengths of 21 P I lines and 126 P II lines (from 3300 to 6900 A). Accuracy for prominent, isolated neutral and ionic lines is estimated to be 28 to 40% and 18 to 30%, respectively. The data and the corresponding theoretical predictions are examined for conformity with the sum rules.-

Miller, M. H.; Roig, R. A.; Bengtson, R. D.

1971-01-01

151

The Concept of the Absolute  

E-print Network

KU ScholarWorks | The University of Kansas Pre-1923 Dissertations and Theses Collection The Concept of the Absolute; Its Historical Development 1910 by C.O. VanDyke This work was digitized by the Scholarly Communications program staff in the KU...

Van Dyke, C. O.

1910-01-01

152

Genetic topography of brain morphology  

PubMed Central

Animal data show that cortical development is initially patterned by genetic gradients largely along three orthogonal axes. We previously reported differences in genetic influences on cortical surface area along an anterior-posterior axis using neuroimaging data of adult human twins. Here, we demonstrate differences in genetic influences on cortical thickness along a dorsal-ventral axis in the same cohort. The phenomenon of orthogonal gradations in cortical organization evident in different structural and functional properties may originate from genetic gradients. Another emerging theme of cortical patterning is that patterns of genetic influences recapitulate the spatial topography of the cortex within hemispheres. The genetic patterning of both cortical thickness and surface area corresponds to cortical functional specializations. Intriguingly, in contrast to broad similarities in genetic patterning, two sets of analyses distinguish cortical thickness and surface area genetically. First, genetic contributions to cortical thickness and surface area are largely distinct; there is very little genetic correlation (i.e., shared genetic influences) between them. Second, organizing principles among genetically defined regions differ between thickness and surface area. Examining the structure of the genetic similarity matrix among clusters revealed that, whereas surface area clusters showed great genetic proximity with clusters from the same lobe, thickness clusters appear to have close genetic relatedness with clusters that have similar maturational timing. The discrepancies are in line with evidence that the two traits follow different mechanisms in neurodevelopment. Our findings highlight the complexity of genetic influences on cortical morphology and provide a glimpse into emerging principles of genetic organization of the cortex. PMID:24082094

Chen, Chi-Hua; Fiecas, Mark; Gutierrez, E. D.; Panizzon, Matthew S.; Eyler, Lisa T.; Vuoksimaa, Eero; Thompson, Wesley K.; Fennema-Notestine, Christine; Hagler, Donald J.; Jernigan, Terry L.; Neale, Michael C.; Franz, Carol E.; Lyons, Michael J.; Fischl, Bruce; Tsuang, Ming T.; Dale, Anders M.; Kremen, William S.

2013-01-01

153

Sensory properties of menthol and smoking topography  

PubMed Central

Although there is a great deal known about menthol as a flavoring agent in foods and confections, less is known about the particular sensory properties of menthol cigarette smoke. Similarly, although smoking topography (the unique way an individual smokes a cigarette) has been well studied using non-menthol cigarettes, there is relatively less known about how menthol affects smoking behavior. The objective of this review is to assess the sensory properties of menthol tobacco smoke, and smoking topography associated with menthol cigarettes. The cooling, analgesic, taste, and respiratory effects of menthol are well established, and studies have indicated that menthol’s sensory attributes can have an influence on the positive, or rewarding, properties associated smoking, including ratings of satisfaction, taste, perceived smoothness, and perceived irritation. Despite these sensory properties, the data regarding menthol’s effect on smoking topography are inconsistent. Many of the topography studies have limitations due to various methodological issues. PMID:21624149

2011-01-01

154

Scholte waves generated by seafloor topography  

E-print Network

Seafloor topography can excite strong interface waves called Scholte waves that are often dispersive and characterized by slow propagation but large amplitude. This type of wave can be used to invert for near seafloor shear ...

Zheng, Yingcai

2012-01-01

155

Enhanced Characterization of Niobium Surface Topography  

SciTech Connect

Surface topography characterization is a continuing issue for the Superconducting Radio Frequency (SRF) particle accelerator community. Efforts are underway to both to improve surface topography, and its characterization and analysis using various techniques. In measurement of topography, Power Spectral Density (PSD) is a promising method to quantify typical surface parameters and develop scale-specific interpretations. PSD can also be used to indicate how chemical processes modifiesy the roughnesstopography at different scales. However, generating an accurate and meaningful topographic PSD of an SRF surface requires careful analysis and optimization. In this report, polycrystalline surfaces with different process histories are sampled with AFM and stylus/white light interferometer profilometryers and analyzed to indicate trace topography evolution at different scales. evolving during etching or polishing. Moreover, Aan optimized PSD analysis protocol will be offered to serve the SRF surface characterization needs is presented.

Chen Xu, Hui Tian, Charles Reece, Michael Kelley

2011-12-01

156

Evaluating Marie Byrd Land stability using an improved basal topography  

NASA Astrophysics Data System (ADS)

Prior understanding of the ice-sheet setting in Marie Byrd Land (MBL) was derived primarily from geologic and geochemical studies of the current nunataks, with very few geophysical surveys imaging the ice covered regions. The geologic context suggested that the ice rests on a broad regional high, in contrast to the deep basins and trenches that characterize the majority of West Antarctica. This assumed topography would favor long-term stability for the West Antarctic Ice Sheet (WAIS) in MBL. Airborne geophysical data collected in 2009 reveal a much deeper bed than previously estimated, including a significant trough underlying DeVicq Glacier and evidence for extensive glacial erosion. Using these data, we produce a new map of subglacial topography, with which we model the sensitivity of WAIS to a warming ocean using the ice-sheet model of Pollard and DeConto (2012b). We compare the results to estimates of ice loss during WAIS collapse using the previously defined subglacial topography, to determine the impact of the newly discovered subglacial features. Our results indicate that the topographic changes are not sufficient to destabilize the northern margin of MBL currently feeding the Getz Ice Shelf; the majority of ice loss occurs from flow toward the Siple Coast. However, despite only slight dynamic differences, using the new bed as a boundary condition results in an additional 8 cm of sea-level rise during major glacial retreat, an increase of just over 2%. Precise estimation of past and future ice retreat, as well as a complete understanding of the geologic history of the region, will require a higher resolution picture of the bed topography around the Executive Committee mountains.

Holschuh, N.; Pollard, D.; Alley, R. B.; Anandakrishnan, S.

2014-12-01

157

Corneal topography measurements for biometric applications  

NASA Astrophysics Data System (ADS)

The term biometrics is used to describe the process of analyzing biological and behavioral traits that are unique to an individual in order to confirm or determine his or her identity. Many biometric modalities are currently being researched and implemented including, fingerprints, hand and facial geometry, iris recognition, vein structure recognition, gait, voice recognition, etc... This project explores the possibility of using corneal topography measurements as a trait for biometric identification. Two new corneal topographers were developed for this study. The first was designed to function as an operator-free device that will allow a user to approach the device and have his or her corneal topography measured. Human subject topography data were collected with this device and compared to measurements made with the commercially available Keratron Piccolo topographer (Optikon, Rome, Italy). A third topographer that departs from the standard Placido disk technology allows for arbitrary pattern illumination through the use of LCD monitors. This topographer was built and tested to be used in future research studies. Topography data was collected from 59 subjects and modeled using Zernike polynomials, which provide for a simple method of compressing topography data and comparing one topographical measurement with a database for biometric identification. The data were analyzed to determine the biometric error rates associated with corneal topography measurements. Reasonably accurate results, between three to eight percent simultaneous false match and false non-match rates, were achieved.

Lewis, Nathan D.

158

Barbour, J. B., 1989, Absolute Or Relative Motion?: A Study from Machian Point of View of the Discovery and the Structure of Dynamical Theories, Cambridge, UK: Cambridge University Press.  

E-print Network

Press. Ducheyne, S., 2001, "Isaac Newton on Space and Time: Metaphysician Or Not?", Philosophica, Unpublished Scientific Papers of Isaac Newton; a Selection from the Portsmouth Collection in the University. Power, J. E., 1970, "Henry More and Isaac Newton on Absolute Space", Journal of the History of Ideas, 31

Huggett, Nicholas

159

Numerical modeling and analysis of the effect of complex Greek topography on tornadogenesis  

NASA Astrophysics Data System (ADS)

Tornadoes have been reported in Greece over recent decades in specific sub-geographical areas and have been associated with strong synoptic forcing. While it has been established that meteorological conditions over Greece are affected at various scales by the significant variability of topography, the Ionian Sea to the west and the Aegean Sea to the east, there is still uncertainty regarding topography's importance on tornadic generation and development. The aim of this study is to investigate the role of topography in significant tornadogenesis events that were triggered under strong synoptic scale forcing over Greece. Three tornado events that occurred over the last years in Thebes (Boeotia, 17 November 2007), Vrastema (Chalkidiki, 12 February 2010) and Vlychos (Lefkada, 20 September 2011) were selected for numerical experiments. These events were associated with synoptic scale forcing, while their intensities were T4-T5 (on the TORRO scale), causing significant damage. The simulations were performed using the non-hydrostatic weather research and forecasting model (WRF), initialized by European Centre for Medium-Range Weather Forecasts (ECMWF) gridded analyses, with telescoping nested grids that allow for the representation of atmospheric circulations ranging from the synoptic scale down to the mesoscale. In the experiments, the topography of the inner grid was modified by: (a) 0% (actual topography) and (b) -100% (without topography), making an effort to determine whether the occurrence of tornadoes - mainly identified by various severe weather instability indices - could be indicated by modifying topography. The principal instability variables employed consisted of the bulk Richardson number (BRN) shear, the energy helicity index (EHI), the storm-relative environmental helicity (SRH), and the maximum convective available potential energy (MCAPE, for parcels with maximum ?e). Additionally, a model verification was conducted for every sensitivity experiment accompanied by analysis of the absolute vorticity budget. Numerical simulations revealed that the complex topography constituted an important factor during the 17 November 2007 and 12 February 2010 events, based on EHI, SRH, BRN, and MCAPE analyses. Conversely, topography around the 20 September 2011 event was characterized as the least significant factor based on EHI, SRH, BRN, and MCAPE analyses.

Matsangouras, I. T.; Pytharoulis, I.; Nastos, P. T.

2014-07-01

160

Evaluation of corneal thickness and topography in normal eyes using the Orbscan corneal topography system  

Microsoft Academic Search

AIMSTo map the thickness, elevation (anterior and posterior corneal surface), and axial curvature of the cornea in normal eyes with the Orbscan corneal topography system.METHODS94 eyes of 51 normal subjects were investigated using the Orbscan corneal topography system. The anterior and posterior corneal elevation maps were classified into regular ridge, irregular ridge, incomplete ridge, island, and unclassified patterns, and the

Zuguo Liu; Andrew J Huang; Stephen C Pflugfelder

1999-01-01

161

Absolute image registration for geosynchronous satellites  

NASA Technical Reports Server (NTRS)

A procedure for the absolute registration of earth images acquired by cameras on geosynchronous satellites is described. A conventional least squares process is used to estimate navigational parameters and camera pointing biases from observed minus computed landmark line and element numbers. These estimated parameters along with orbit and attitude dynamic models are used to register images, employing an automated grey-level correlation technique, inside the span represented by the landmark data. Experimental results obtained from processing the SMS-2 observation data base covering May 2, 1979 through May 20, 1979 show registration accuracies with a standard deviation of less than two pixels if the registration is within the landmark data span. It is also found that accurate registration can be expected for images obtained up to 48 hours outside of the landmark data span.

Nankervis, R.; Koch, D.; Sielski, H.; Hall, D.

1980-01-01

162

Mantle convection and core-mantle boundary topography: explanations and implications  

NASA Astrophysics Data System (ADS)

Recent seismic inferences of the topography on the core-mantle boundary (CMB) constitute a new and potentially important constraint on the dynamics of the thermal convective circulation in the Earth's mantle. We employ viscous flow models for the mantle to predict the flow-induced deflections of the CMB that are expected on the basis of seismic tomographic inferences of internal mantle density heterogeneity. The good agreement between our theoretical predictions and the seismically inferred CMB deflections of Morelli and Dziewonski (1987) suggests that the latter may indeed be good approximations to the dynamically induced CMB topography. The amplitude of the seismically inferred CMB topography may be construed to provide a direct constraint on the temperature derivative of seismic P-wave velocity in the lower mantle and we determine a value for this parameter, in the course of fitting the data, that differs significantly from the value determined by laboratory measurements as appropriate for upper-mantle phases. The seismically observed topography on the CMB is also shown to provide evidence favouring the whole-mantle convection hypothesis and in this connection we argue that deep penetration of subducted lithospheric slabs into the lower mantle is likely to be responsible for controlling many of the features of this topography.

Forte, Alessandro M.; Peltier, W. Richard

1991-02-01

163

PROJECTIVE GROUP STRUCTURES AS ABSOLUTE GALOIS STRUCTURES  

E-print Network

PROJECTIVE GROUP STRUCTURES AS ABSOLUTE GALOIS STRUCTURES of a cover to a cartesioan square . . . . . . . . . . . . . . * *. 1 4. Projective groups structures of the Main Theorem . . . . . . . . . . . . . . . . . . . . 1 14. Projective group structures as absolute

164

PROJECTIVE GROUP STRUCTURES AS ABSOLUTE GALOIS STRUCTURES  

E-print Network

PROJECTIVE GROUP STRUCTURES AS ABSOLUTE GALOIS STRUCTURES. A proper profinite group structure G is projective if and only if G* * is the absolute Galois group to a cartesian square . . . . . . . . . . . . . . . * * 19 4. Projective group structures

Pop, Florian

165

Effects of patterned topography on biofilm formation  

NASA Astrophysics Data System (ADS)

Bacterial biofilms are a population of bacteria attached to each other and irreversibly to a surface, enclosed in a matrix of self-secreted polymers, among others polysaccharides, proteins, DNA. Biofilms cause persisting infections associated with implanted medical devices and hospital acquired (nosocomial) infections. Catheter-associated urinary tract infections (CAUTIs) are the most common type of nosocomial infections accounting for up to 40% of all hospital acquired infections. Several different strategies, including use of antibacterial agents and genetic cues, quorum sensing, have been adopted for inhibiting biofilm formation relevant to CAUTI surfaces. Each of these methods pertains to certain types of bacteria, processes and has shortcomings. Based on eukaryotic cell topography interaction studies and Ulva linza spore studies, topographical surfaces were suggested as a benign control method for biofilm formation. However, topographies tested so far have not included a systematic variation of size across basic topography shapes. In this study patterned topography was systematically varied in size and shape according to two approaches 1) confinement and 2) wetting. For the confinement approach, using scanning electron microscopy and confocal microscopy, orienting effects of tested topography based on staphylococcus aureus (s. aureus) (SH1000) and enterobacter cloacae (e. cloacae) (ATCC 700258) bacterial models were identified on features of up to 10 times the size of the bacterium. Psuedomonas aeruginosa (p. aeruginosa) (PAO1) did not show any orientational effects, under the test conditions. Another important factor in medical biofilms is the identification and quantification of phenotypic state which has not been discussed in the literature concerning bacteria topography characterizations. This was done based on antibiotic susceptibility evaluation and also based on gene expression analysis. Although orientational effects occur, phenotypically no difference was observed between the patterned topography tested. Another potential strategy for biofilm control through patterned topography is based on the design of robust non-wetting surfaces with undercut feature geometries, characterized by 1) breakthrough pressure and 2) triple phase contact line model. It was found that height and presence of undercut had statistically significant effects, directly proportional to breakthrough pressures, whereas extent of undercut did not. A predictive triple phase contact line model was also developed. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

Vasudevan, Ravikumar

166

Visualization of lumbar muscle contraction synergy using surface electromyography (sEMG) streaming topography  

Microsoft Academic Search

Because of the difficulty in analysis and interpretation of surface electromyography (sEMG), the specific muscle contraction synergy associated with low back pain continues to be debated. Streaming topography is a novel method of continuously visualizing the distribution of sEMG signals during dynamic motion to provide a more comprehensive examination and subsequent insight into the synergy of muscle recruitment pattern. The

Yong Hu; J. N. F. Mak; W. W. Lu; K. M. C. Cheung; K. D. K. Luk

2004-01-01

167

Absolutely Continuous Convolutions of Singular Measures and an Application to the Square Fibonacci Hamiltonian  

E-print Network

We prove for the square Fibonacci Hamiltonian that the density of states measure is absolutely continuous for almost all pairs of small coupling constants. This is obtained from a new result we establish about the absolute continuity of convolutions of measures arising in hyperbolic dynamics with exact-dimensional measures.

David Damanik; Anton Gorodetski; Boris Solomyak

2013-06-18

168

Absolute MR thermometry using nanocarriers.  

PubMed

Accurate time-resolved temperature mapping is crucial for the safe use of hyperthermia-mediated drug delivery. We here propose a magnetic resonance imaging temperature mapping method in which drug delivery systems serve not only to improve tumor targeting, but also as an accurate and absolute nano-thermometer. This method is based on the temperature-dependent chemical shift difference between water protons and the protons in different groups of drug delivery systems. We show that the chemical shift of the protons in the ethylene oxide group in polyethylene glycol (PEG) is temperature-independent, whereas the proton resonance of water decreases with increasing temperature. The frequency difference between both resonances is linear and does not depend on pH and physiological salt conditions. In addition, we show that the proton resonance of the methyl group in N-(2-hydroxypropyl)-methacrylamide (HPMA) is temperature-independent. Therefore, PEGylated liposomes, polymeric mPEG-b-pHPMAm-Lac2 micelles and HPMA copolymers can provide a temperature-independent reference frequency for absolute magnetic resonance (MR) thermometry. Subsequently, we show that multigradient echo MR imaging with PEGylated liposomes in situ allows accurate, time-resolved temperature mapping. In conclusion, nanocarrier materials may serve as highly versatile tools for tumor-targeted drug delivery, acting not only as hyperthermia-responsive drug delivery systems, but also as accurate and precise nano-thermometers. PMID:24706612

Deckers, Roel; Sprinkhuizen, Sara M; Crielaard, Bart J; Ippel, Johannes H; Boelens, Rolf; Bakker, Chris J G; Storm, Gert; Lammers, Twan; Bartels, Lambertus W

2014-01-01

169

Absolute Neutron Emission Measurement in Burning Plasma Experiments  

SciTech Connect

The absolute measurement of neutron emission rate from the whole plasma is a very important diagnostics as a fusion power monitor in fusion experimental devices with D-T or D-T operations. Here measurement techniques of time-resolved and time-integrated absolute neutron emission on the present tokamaks and ITER are reviewed. In the present tokamaks, fission chamber installed outside the vacuum vessel are very popular in the absolute neutron emission rate measurement. As well as conventional neutron monitors installed outside the vacuum vessel, in-vessel neutron monitors using micro fission chamber are proposed for the absolute neutron emission rate measurement in ITER. The neutron activation system provides time-integrated measurements of the total neutron yield with high accuracy by using well known neutron reaction cross sections, which is useful to maintain a robust measure of fusion energy production with stability and wide dynamic range. The calibration of the relation between the neutron emission rate in the whole plasma and the output of neutron monitor is the most important issue in the absolute neutron emission rate measurements. The calibration of the neutron detectors has been performed by moving a neutron source such as a {sup 252}Cf neutron or a small accelerator-based neutron generator. For the calibration in ITER, the neutron generator with neutron emission rate of 10{sup 11} s{sup -1} or stronger is required to obtain high accuracy.

Nishitani, Takeo; Ishikawa, Masao; Kondoh, Takashi; Kusama, Yoshinori [Japan Atomic Energy Agency, Naka, Ibaraki-ken, 311-0193 (Japan); Asai, Keisuke [Nagoya University, Chikusa-ku, Nagoya, 464-8603 (Japan); Sasao, Mmamiko [Tohoku University, Aoba-ku, Sendai, 980-8579 (Japan)

2008-03-12

170

Detecting and Quantifying Topography in Neural Maps  

PubMed Central

Topographic maps are an often-encountered feature in the brains of many species, yet there are no standard, objective procedures for quantifying topography. Topographic maps are typically identified and described subjectively, but in cases where the scale of the map is close to the resolution limit of the measurement technique, identifying the presence of a topographic map can be a challenging subjective task. In such cases, an objective topography detection test would be advantageous. To address these issues, we assessed seven measures (Pearson distance correlation, Spearman distance correlation, Zrehen's measure, topographic product, topological correlation, path length and wiring length) by quantifying topography in three classes of cortical map model: linear, orientation-like, and clusters. We found that all but one of these measures were effective at detecting statistically significant topography even in weakly-ordered maps, based on simulated noisy measurements of neuronal selectivity and sparse sampling of the maps. We demonstrate the practical applicability of these measures by using them to examine the arrangement of spatial cue selectivity in pallid bat A1. This analysis shows that significantly topographic arrangements of interaural intensity difference and azimuth selectivity exist at the scale of individual binaural clusters. PMID:24505279

Yarrow, Stuart; Razak, Khaleel A.; Seitz, Aaron R.; Series, Peggy

2014-01-01

171

Transient thermal effects below complex topographies  

Microsoft Academic Search

The topographical perturbation of steady-state subsurface temperature fields has been an important issue in geothermal interpretations throughout the past century. This paper reports a numerical study, which considers the possible influence of terrain topography on transient temperature signals. Typical morphological situations over wide areas in central Europe affect most likely that same depth range which also contains the temperature signals

Thomas Kohl

1999-01-01

172

Absolute radiance re-calibration of FIRST  

NASA Astrophysics Data System (ADS)

The FIRST (Far-InfraRed Spectroscopy of the Troposphere) instrument is a 10 to 100 micron spectrometer with 0.64 micron resolution designed to measure the complete mid and far-infrared radiance of the Earth's Atmosphere. FIRST has been successfully used to obtain high-quality atmospheric radiance data from the ground and from a high-altitude balloon. A Fourier transform interferometer is used to provide the spectral resolution and two on-board blackbodies are used for calibration. This paper discusses the recent re-calibration of FIRST at Space Dynamics Laboratory for absolute radiance accuracy. The calibration used the LWRICS (Long Wave Infrared Calibration Source) blackbody, which NIST testing shows to be accurate to the ~100 mK level in brightness temperature. There are several challenges to calibrating FIRST, including the large dynamic range, out of phase light, and drift in the interferogram phase. The accuracy goal for FIRST was 0.2 K over most of the 10 to 100 micron range, and results show FIRST meets this goal for a range of target temperatures.

Latvakoski, Harri; Mlynczak, Martin; Johnson, David; Cageao, Rich; Swasey, Jason; Johnson, Kendall

2012-10-01

173

Representation of topography by porous barriers and objective interpolation of topographic data  

NASA Astrophysics Data System (ADS)

We present a porous medium approach to representing topography, and a new algorithm for the objective interpolation of topography, for use in ocean circulation models of fixed resolution. The representation and algorithm makes use of two concepts; impermeable thin walls and porous barriers. Impermeable thin walls allow the representation of knife-edge sub-grid-scale barriers that block lateral flow between model grid cells. Porous barriers permit the sub-grid scale geometry to modulate lateral transport as a function of elevation. We find that the porous representation and the resulting interpolated topography retains key features, such as overflow sill depths, without compromising other dynamically relevant aspects, such as mean ocean depth for a cell. The accurate representation of the ocean depth is illustrated in a simple model of a tsunami that has a cross-basin travel time very much less dependent on horizontal resolution than when using conventional topographic interpolation and representation.

Adcroft, Alistair

2013-07-01

174

Wind Energy Forecasting Utilizing High Resolution Topography in the WRF Model  

NASA Astrophysics Data System (ADS)

Local topography has considerable effects on the dynamics of low-level winds. Many wind farms take advantage of the local landscape when deciding where to place their turbines. In this study we attempt to better model these unique local features by representing them more accurately. The current default WRF topography has a maximum resolution of 30 arc seconds which at mid-latitudes is roughly 1 kilometer whereas the USGS database currently covers 95% of the United States at 30 meter resolution. In this study the 1/3 arc second national elevation database (NED13) is interfaced with the WRF model using a tool developed specifically to make this process simple and the effects of modeling with the updated topography are investigated.

Beechler, B. E.; Zupanski, D.

2012-12-01

175

The influence of topography and vegetation self-organization over resource fluxes in wetland ecosystems  

NASA Astrophysics Data System (ADS)

While it is recognized that topography and vegetation self-organization (SO) are both first order controls over ecosystem dynamics, the discrete contributions that these two controls have over ecosystem functioning have not been studied in any rigorous way. This work is focused on systematically isolating the separate and combined impacts of topography and SO over vegetation dynamics. We simulate the steady state and transient dynamics of nitrogen-limited patterned peat vegetation observed in the bogs of northern Siberia. We do so across a realistic range of land slopes, nutrient limitation values, and rainfall amounts. Simulation results show that on relatively shallow slopes, vegetation SO is a primary control over the spatial arrangement of vegetation, and that such self-organized arrangements yield the most efficient capture of ecosystem resources. However, as slope increases, and or resource limitation is low, topography begins to exert its control over the temporal and spatial dynamics. As will be discussed, these results suggest a simple continuum framework, valid across biomes, for understanding the interplay between these two first order controls. Specifically, as resources (e.g., water, nutrients) increase, ecosystem dynamics shift towards topographic control, while when resources are reduced, ecosystem dynamics shift towards vegetation SO control.

Stieglitz, Marc; Cheng, Yiwei; Truk, Greg; Engel, Victor; Ross, Joshua

2014-05-01

176

X-Ray Topography Techniques for Defect Characterization of Crystals  

NASA Astrophysics Data System (ADS)

X-ray topography is the general term for a family of x-ray diffraction imaging techniques capable of providing information on the nature and distribution of structural defects such as dislocations, inclusions/precipitates, stacking faults, growth sector boundaries, twins, and low-angle grain boundaries in single-crystal materials. From the first x-ray diffraction image, recorded by Berg in 1931, to the double-crystal technique developed by Bond and Andrus in 1952 and the transmission technique developed by Lang in 1958 through to present-day synchrotron-radiation-based techniques, x-ray topography has evolved into a powerful, nondestructive method for the rapid characterization of large single crystals of a wide range of chemical compositions and physical properties, such as semiconductors, oxides, metals, and organic materials. Different defects are readily identified through interpretation of contrast using well-established kinematical and dynamical theories of x-ray diffraction. This method is capable of imaging extended defects in the entire volume of the crystal and in some cases in wafers with devices fabricated on them. It is well established as an indispensable tool for the development of growth techniques for highly perfect crystals (for, e.g., Czochralski growth of silicon) for semiconductor and electronic applications. The capability of in situ characterization during crystal growth, heat treatment, stress application, device operation, etc. to study the generation, interaction, and propagation of defects makes it a versatile technique to study many materials processes.

Raghothamachar, Balaji; Dudley, Michael; Dhanaraj, Govindhan

177

Ice sheet motion and topography from radar interferometry  

Microsoft Academic Search

Both topography and motion information are present in repeat pass ERS-1 interferograms over ice sheets. The authors demonstrate that the topography is separable from the surface displacement field when a sequence of radar images are available. If the velocity field is constant over the time span of observation, the topography can be derived from differential interferograms formed from sequential observations.

Ronald Kwok; Mark A. Fahnestock

1996-01-01

178

CZARNOTA ET AL.:DYNAMIC TOPOGRAPHY AROUND AUSTRALIA Residual Topography Estimates From Wide Angle Seismic  

E-print Network

maximum LSD57 Curray et al. (1977) 108.150 -14.950 -34 -87 -153 maximum LSD58 Curray et al. (1977) 115.550 -13.783 -472 -554 -651 maximum LSD59 Curray et al. (1977) 118.433 -13.517 -370 -451 -546 maximum MSN12

Cambridge, University of

179

New null screen design for corneal topography  

NASA Astrophysics Data System (ADS)

In this work we report the design of a null screen for corneal topography. Here we assume that the corneal surface is an ellipsoid with a diameter of 12 mm and a curvature radius of 7.8 mm. To avoid the difficulties in the alignment of the test system due to the face contour (eyebrows, nose, or eyelids), we design a conical null-screen with spots (similar to ellipses) drawn on it in such a way that its image, which is formed by reflection on the test surface, becomes an exact radial array of circular spots if the surface is perfect. Additionally, we performed a numerical simulation introducing Gaussian random errors in the coordinates of the centroids of the spots on the image plane, and in the coordinates of the sources (spots on the null-screen) in order to obtain the conical null-screen that reduces the error in the evaluation of the topography.

Campos-García, Manuel; Estrada-Molina, Amilcar; Díaz-Uribe, Rufino

2011-09-01

180

Absolute configuration of isovouacapenol C  

PubMed Central

The title compound, C27H34O5 {systematic name: (4aR,5R,6R,6aS,7R,11aS,11bR)-4a,6-dihy­droxy-4,4,7,11b-tetra­methyl-1,2,3,4,4a,5,6,6a,7,11,11a,11b-dodeca­hydro­phenanthro[3,2-b]furan-5-yl benzoate}, is a cassane furan­oditerpene, which was isolated from the roots of Caesalpinia pulcherrima. The three cyclo­hexane rings are trans fused: two of these are in chair conformations with the third in a twisted half-chair conformation, whereas the furan ring is almost planar (r.m.s. deviation = 0.003?Å). An intra­molecular C—H?O inter­action generates an S(6) ring. The absolute configurations of the stereogenic centres at positions 4a, 5, 6, 6a, 7, 11a and 11b are R, R, R, S, R, S and R, respectively. In the crystal, mol­ecules are linked into infinite chains along [010] by O—H?O hydrogen bonds. C?O [3.306?(2)–3.347?(2)?Å] short contacts and C—H?? inter­actions also occur. PMID:21588364

Fun, Hoong-Kun; Yodsaoue, Orapun; Karalai, Chatchanok; Chantrapromma, Suchada

2010-01-01

181

Sensory properties of menthol and smoking topography  

Microsoft Academic Search

Although there is a great deal known about menthol as a flavoring agent in foods and confections, less is known about the\\u000a particular sensory properties of menthol cigarette smoke. Similarly, although smoking topography (the unique way an individual\\u000a smokes a cigarette) has been well studied using non-menthol cigarettes, there is relatively less known about how menthol affects\\u000a smoking behavior. The

Deirdre Lawrence; Brie Cadman; Allison C Hoffman

2011-01-01

182

Global relationship between oceanic geoid and topography  

NASA Technical Reports Server (NTRS)

The transfer function of geoid over topography as a function of wavelength is derived. The relationship between oceanic geoid and seafloor depth is analyzed. The correction of the geoid and topological data for thermal cooling of the oceanic lithosphere, sediment loading, and crustal thickening induced by volcanism under large ocean plateaus is discussed. The global residual depth and geoid anomalies are computed. The admittance and correlation between residual depth and geoid anomalies as a function of wavelength are examined.

Cazenave, A.; Dominh, K.; Allegre, C. J.; Marsh, J. G.

1986-01-01

183

Topography over South America from ERS altimetry  

NASA Technical Reports Server (NTRS)

The results of the surface topography mapping of South America during the ERS-1 geodetic mission are presented. The altimeter waveforms, the range measurement, and the internal and Doppler range corrections were obtained. The atmospheric corrections and solid tides were calculated. Comparisons between Shuttle laser altimetry and ERS-1 altimetry grid showed good agreement. Satellite radar altimetry data can be used to improve the topographic knowledge of regions for which only poor elevation data currently exist.

Brenner, Anita; Frey, Herb; DiMarzio, John; Tsaoussi, Lucia

1997-01-01

184

Diffraction imaging (topography) with monochromatic synchrotron radiation  

NASA Technical Reports Server (NTRS)

Structural information of special interest to crystal growers and device physicists is now available from high resolution monochromatic synchrotron diffraction imaging (topography). In the review, the importance of superior resolution in momentum transfer and in space is described, and illustrations are taken from a variety of crystals: gallium arsenide, cadmium telluride, mercuric iodide, bismuth silicon oxide, and lithium niobate. The identification and understanding of local variations in crystal growth processes are shown. Finally, new experimental opportunities now available for exploitation are indicated.

Steiner, Bruce; Kuriyama, Masao; Dobbyn, Ronald C.; Laor, Uri

1988-01-01

185

Impacts of Topography on Sea Level Change  

NSDL National Science Digital Library

This lesson is comprised of three activities (three class periods). Students use web-based animations to explore the impacts of ice melt and changes to sea level. Students are introduced to topographic maps by doing a hands-on activity to model the contours of an island. Students examine the relationship between topography and sea level change by mapping changing shorelines using a topographic map.

Whitfield, Lise; Mcmillon, Bill; Scotchmoor, Judy; Stoffer, Phil; DLESE (Digital Library for Earth System Education)

186

EAARL topography: Gateway National Recreation Area  

USGS Publications Warehouse

This Web site contains Lidar-derived topography (bare earth) maps and GIS files for the Sandy Hook Unit within Gateway National Recreation Area in New Jersey. These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, the National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

Brock, John C.; Wright, C. Wayne; Patterson, Matt; Nayegandhi, Amar; Patterson, Judd

2007-01-01

187

Prelaunch absolute radiometric calibration of LANDSAT-4 protoflight Thematic Mapper  

NASA Technical Reports Server (NTRS)

Results are summarized and analyzed from several prelaunch tests with a 122 cm integrating sphere used as part of the absolute radiometric calibration experiments for the protoflight TM sensor carried on the LANDSAT-4 satellite. The calibration procedure is presented and the radiometric sensitivity of the TM is assessed. The internal calibrator and dynamic range after calibration are considered. Tables show dynamic range after ground processing, spectral radiance to digital number and digital number to spectral radiance values for TM bands 1, 2, 3, 4, 5, 7 and for channel 4 of band 6.

Barker, J. L.; Ball, D. L.; Leung, K. C.; Walker, J. A.

1984-01-01

188

Absolute Income, Relative Income, and Happiness  

ERIC Educational Resources Information Center

This paper uses data from the World Values Survey to investigate how an individual's self-reported happiness is related to (i) the level of her income in absolute terms, and (ii) the level of her income relative to other people in her country. The main findings are that (i) both absolute and relative income are positively and significantly…

Ball, Richard; Chernova, Kateryna

2008-01-01

189

Absolute Optical Metrology: Nanometers to Kilometers  

Microsoft Academic Search

We provide an overview of developments in high-accuracy absolute optical metrology with emphasis on space-based applications. Specific work on the Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor is described along with novel applications of the sensor.

S. Dubovitsky; O. P. Lay; R. D. Peters; C. C. Liebe

2005-01-01

190

Nonequilibrium equalities in absolutely irreversible processes  

NASA Astrophysics Data System (ADS)

We generalize nonequilibrium integral equalities to situations involving absolutely irreversible processes for which the forward-path probability vanishes and the entropy production diverges, rendering conventional integral fluctuation theorems inapplicable. We identify the mathematical origins of absolute irreversibility as the singularity of probability measure. We demonstrate the validity of the obtained equalities for several models.

Murashita, Yûto; Funo, Ken; Ueda, Masahito

2014-10-01

191

Dependence of Eemian Greenland temperature reconstructions on the ice sheet topography  

NASA Astrophysics Data System (ADS)

The influence of a reduced Greenland ice sheet (GrIS) on Greenland's surface climate during the Eemian interglacial is studied using a comprehensive climate model. We find a distinct impact of changes in the GrIS topography on Greenland's surface air temperatures (SAT) even when correcting for changes in surface elevation which influences SAT through the lapse rate effect. The resulting lapse rate corrected SAT anomalies are thermodynamically driven by changes in the local surface energy balance rather than dynamically caused through anomalous advection of warm/cold air masses. The large-scale circulation is indeed very stable among all sensitivity experiments and the NH flow pattern does not depend on Greenland's topography in the Eemian. In contrast, Greenland's surface energy balance is clearly influenced by changes in the GrIS topography and this impact is seasonally diverse. In winter, the variable reacting strongest to changes in the topography is the sensible heat flux (SHFLX). The reason is its dependence on surface winds, which themselves are controlled to a large extent by the shape of the GrIS. Hence, regions where a receding GrIS causes higher surface wind velocities also experience anomalous warming through SHFLX. Vice-versa, regions that become flat and ice-free are characterized by low wind speeds, low SHFLX and anomalous cold winter temperatures. In summer, we find surface warming induced by a decrease in surface albedo in deglaciated areas and regions which experience surface melting. The Eemian temperature records derived from Greenland proxies, thus, likely include a temperature signal arising from changes in the GrIS topography. For the NEEM ice core site, our model suggests that up to 3.2 °C of the annual mean Eemian warming can be attributed to these topography-related processes and hence is not necessarily linked to large-scale climate variations.

Merz, N.; Born, A.; Raible, C. C.; Fischer, H.; Stocker, T. F.

2013-12-01

192

Dependence of Eemian Greenland temperature reconstructions on the ice sheet topography  

NASA Astrophysics Data System (ADS)

The influence of a reduced Greenland Ice Sheet (GrIS) on Greenland's surface climate during the Eemian interglacial is studied using a set of simulations with different GrIS realizations performed with a comprehensive climate model. We find a distinct impact of changes in the GrIS topography on Greenland's surface air temperatures (SAT) even when correcting for changes in surface elevation, which influences SAT through the lapse rate effect. The resulting lapse-rate-corrected SAT anomalies are thermodynamically driven by changes in the local surface energy balance rather than dynamically caused through anomalous advection of warm/cold air masses. The large-scale circulation is indeed very stable among all sensitivity experiments and the Northern Hemisphere (NH) flow pattern does not depend on Greenland's topography in the Eemian. In contrast, Greenland's surface energy balance is clearly influenced by changes in the GrIS topography and this impact is seasonally diverse. In winter, the variable reacting strongest to changes in the topography is the sensible heat flux (SHF). The reason is its dependence on surface winds, which themselves are controlled to a large extent by the shape of the GrIS. Hence, regions where a receding GrIS causes higher surface wind velocities also experience anomalous warming through SHF. Vice-versa, regions that become flat and ice-free are characterized by low wind speeds, low SHF, and anomalous low winter temperatures. In summer, we find surface warming induced by a decrease in surface albedo in deglaciated areas and regions which experience surface melting. The Eemian temperature records derived from Greenland proxies, thus, likely include a temperature signal arising from changes in the GrIS topography. For the Eemian ice found in the NEEM core, our model suggests that up to 3.1 °C of the annual mean Eemian warming can be attributed to these topography-related processes and hence is not necessarily linked to large-scale climate variations.

Merz, N.; Born, A.; Raible, C. C.; Fischer, H.; Stocker, T. F.

2014-06-01

193

Absolute instability of the Gaussian wake profile  

NASA Technical Reports Server (NTRS)

Linear parallel-flow stability theory has been used to investigate the effect of viscosity on the local absolute instability of a family of wake profiles with a Gaussian velocity distribution. The type of local instability, i.e., convective or absolute, is determined by the location of a branch-point singularity with zero group velocity of the complex dispersion relation for the instability waves. The effects of viscosity were found to be weak for values of the wake Reynolds number, based on the center-line velocity defect and the wake half-width, larger than about 400. Absolute instability occurs only for sufficiently large values of the center-line wake defect. The critical value of this parameter increases with decreasing wake Reynolds number, thereby indicating a shrinking region of absolute instability with decreasing wake Reynolds number. If backflow is not allowed, absolute instability does not occur for wake Reynolds numbers smaller than about 38.

Hultgren, Lennart S.; Aggarwal, Arun K.

1987-01-01

194

The Reliability of Puff Topography and Subjective Responses During Ad lib Smoking of a Single Cigarette  

PubMed Central

Introduction: Acute smoking behavior (i.e., puff topography) and subjective responses during the ad lib smoking of a single cigarette in the laboratory may provide useful measures of smoking reinforcement and reward, respectively. However, the reliability of such measures is not clear, leaving uncertain the utility of a single assessment of smoking behavior as an individual difference measure. Methods: Dependent smokers (N = 94) smoked normally prior to each of 4 laboratory sessions during which they were instructed to smoke 1 cigarette of their preferred brand in ad libitum and unblinded fashion and then rate it for subjective effects. Puff topography (puff number, total volume, and maximum volume) was assessed via portable Clinical Research Support System device. Subjective reward and perception were assessed by visual analog scales of “liking” and “how strong,” respectively. The reliability of puff topography and subjective measures was determined across days by intra-class correlations (ICCs). Differences due to sex and nicotine dependence (high and low Fagerström Test for Nicotine Dependence score) were also examined. Results: Reliability was highly significant for each measure. ICCs were .70 for total puff volume, .60 for maximum puff volume, .73 for puff number, .64 for liking, and .78 for how strong. Reliability generally did not differ by sex or dependence, but absolute values for total volume and maximum puff volume were greater in men and in high dependent smokers. Liking was also greater in high dependent smokers. Conclusions: Puff topography and subjective measures during the ad lib smoking of a single cigarette are highly reliable. Smoking responses during a single ad lib smoking session may be useful in identifying stable individual differences in smoking reinforcement and reward. PMID:22039077

Karelitz, Joshua L.; Giedgowd, Grace E.; Conklin, Cynthia A.

2012-01-01

195

Macromolecular Topography Leaps into the Digital Age  

NASA Technical Reports Server (NTRS)

A low-cost, real-time digital topography system is under development which will replace x-ray film and nuclear emulsion plates. The imaging system is based on an inexpensive surveillance camera that offers a 1000x1000 array of 8 im square pixels, anti-blooming circuitry, and very quick read out. Currently, the system directly converts x-rays to an image with no phosphor. The system is small and light and can be easily adapted to work with other crystallographic equipment. Preliminary images have been acquired of cubic insulin at the NSLS x26c beam line. NSLS x26c was configured for unfocused monochromatic radiation. Six reflections were collected with stills spaced from 0.002 to 0.001 degrees apart across the entire oscillation range that the reflections were in diffracting condition. All of the reflections were rotated to the vertical to reduce Lorentz and beam related effects. This particular CCD is designed for short exposure applications (much less than 1 sec) and so has a relatively high dark current leading to noisy raw images. The images are processed to remove background and other system noise with a multi-step approach including the use of wavelets, histogram, and mean window filtering. After processing, animations were constructed with the corresponding reflection profile to show the diffraction of the crystal volume vs. the oscillation angle as well as composite images showing the parts of the crystal with the strongest diffraction for each reflection. The final goal is to correlate features seen in reflection profiles captured with fine phi slicing to those seen in the topography images. With this development macromolecular topography finally comes into the digital age.

Lovelace, J.; Bellamy, H.; Snell, E. H.; Borgstahl, G.

2003-01-01

196

EAARL Coastal Topography - Sandy Hook 2007  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Northeast Coastal and Barrier Network, Kingston, RI; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of Gateway National Recreation Area's Sandy Hook Unit in New Jersey, acquired on May 16, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL) was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for pre-survey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Stevens, Sara; Yates, Xan; Bonisteel, Jamie M.

2008-01-01

197

Comparison of parameters describing stratified surface topography  

NASA Astrophysics Data System (ADS)

There are a lot of methods of two-process surface topography description. Some parameters can be computed from material ratio graph. There are included in ISO standards. The methods described in ISO standards 13565-2 (Pk, Ppk, Pvk, Pmr1 and Pmr2) and 13565-3 (Pmq, Pvq and Pmq) are compared in this paper. Profiles with given values of Pmq, Pvq and Pmq parameters and wavelengths were modelled. For these profiles, material ratio curve and Pk, Ppk, Pvk, Pmr1 and Pmr2 parameters were calculated. As a result, dependencies among parameters from ISO 13565-3 and ISO 13565-2 standard were found.

Pawlus, P.; Reizer, R.; Lenart, A.

2014-03-01

198

Evaluation of entire-cornea topography measurement  

NASA Astrophysics Data System (ADS)

We quantitatively evaluated a technique for combining multiple videokeratograph views of different areas of cornea. To achieve this we first simulated target reflection from analytic descriptions of various shapes believed to mimic common corneal topographies. The splicing algorithm used the simulated reflections to achieve a good quality estimation of the shapes. Actual imagery was then acquired of manufactured models of the same shapes and the splicing algorithm was found to achieve a less perfect estimation. The cause was thought mainly to be image blur due to defocus. To investigate this, blur was introduced into the reflection simulation, and the results of the splicing algorithm compared to those found from the actual imagery.

Shevlin, Fergal P.; Klein, Stanley A.; Mandell, Robert B.; Carney, Thom

2000-06-01

199

Bessel Function Model for Corneal Topography  

E-print Network

In this paper we consider a new nonlinear mathematical model for corneal topography formulated as two-point boudary value problem. We derive it from first physical principles and provide some mathematical analysis. The existence and uniqeness theorems are proved as well as various estimates on exact solution. At the end we fit the simplified model based on Modified Bessel Function of the First Kind with the real corneal data consisting of matrix of 123x123 points and obtain an error of order of 1%.

Okrasi?ski, Wojciech

2011-01-01

200

Topography and subduction geometry in the central Andes: Clues to the mechanics of a noncollisional orogen  

NASA Technical Reports Server (NTRS)

The central Andeean orogen between 12 deg and 32 deg S latitude exhibits a high degree of spatial order: principally an extraordinary bilateral symmetry that is common to the Earth's surface, the underlying Wadati-Benioff zone, and the Nazca/South America plate kinematics, which has been stable since the mid-Tertiary. This spatial order must reflect the physical mechanisms of mountain building in this noncollisional orogen. The shapes of the topography and subduction zone can be reduced to symmetric and antisummeric components relative to any verical symmetry plane; the particular plaen which minimizes the antisymmetry (and maximizes the symmetry) is well resolved and is essentially coincident with the stable Euler equator of Nacza/South America relative motion since the mid-Tertiary. That the topography, subduction geometry, and persistent mid-Tertiary plate kinematics share common spatial and geometric elements suggests that he distribution of topography in this orogen depends strongly on the dynamics of subduction. Other factors that might affect the topography and underlying tectonics, such as climate and inherited strutura fabric, which have different spatial characterisitcs, must be of less significance at a continental scale. Furthermore, the small components of asymmetry among the various elements of the orogen appear to be mutually relate in a simple way; it is possible that this coupled asymmetry is associated with a late Teriary change in plate kinematics. These observations suggest that there is a close connection between plate tectonics and the form of the Earth's surface in this noncollisional setting. It follows hta the distribution of topography near convergent plate boundaries may provide a powerful constraing for understanding the dynamics of subduction.

Gephart, John W.

1994-01-01

201

Absolute charge calibration of scintillating screens for relativistic electron detection  

SciTech Connect

We report on new charge calibrations and linearity tests with high-dynamic range for eight different scintillating screens typically used for the detection of relativistic electrons from laser-plasma based acceleration schemes. The absolute charge calibration was done with picosecond electron bunches at the ELBE linear accelerator in Dresden. The lower detection limit in our setup for the most sensitive scintillating screen (KODAK Biomax MS) was 10 fC/mm{sup 2}. The screens showed a linear photon-to-charge dependency over several orders of magnitude. An onset of saturation effects starting around 10-100 pC/mm{sup 2} was found for some of the screens. Additionally, a constant light source was employed as a luminosity reference to simplify the transfer of a one-time absolute calibration to different experimental setups.

Buck, A.; Popp, A.; Schmid, K.; Karsch, S.; Krausz, F. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Ludwig-Maximilians-Universitaet Muenchen, Am Coulombwall 1, D-85748 Garching (Germany); Zeil, K.; Jochmann, A.; Kraft, S. D.; Sauerbrey, R.; Cowan, T.; Schramm, U. [Forschungszentrum Dresden Rossendorf, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Hidding, B.; Kudyakov, T. [Institut fuer Laser und Plasmaphysik, Heinrich-Heine-Universitaet Duesseldorf, Universitaetsstrasse 1, D-40225 Duesseldorf (Germany); Sears, C. M. S.; Veisz, L. [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching (Germany); Pawelke, J. [Forschungszentrum Dresden Rossendorf, Bautzner Landstrasse 400, D-01328 Dresden (Germany); Oncoray, Technische Universitaet Dresden, Fetscher Strasse 74, D-01307 Dresden (Germany)

2010-03-15

202

Reconstituting ring-rafts in bud-mimicking topography of model membranes  

NASA Astrophysics Data System (ADS)

During vesicular trafficking and release of enveloped viruses, the budding and fission processes dynamically remodel the donor cell membrane in a protein- or a lipid-mediated manner. In all cases, in addition to the generation or relief of the curvature stress, the buds recruit specific lipids and proteins from the donor membrane through restricted diffusion for the development of a ring-type raft domain of closed topology. Here, by reconstituting the bud topography in a model membrane, we demonstrate the preferential localization of cholesterol- and sphingomyelin-enriched microdomains in the collar band of the bud-neck interfaced with the donor membrane. The geometrical approach to the recapitulation of the dynamic membrane reorganization, resulting from the local radii of curvatures from nanometre-to-micrometre scales, offers important clues for understanding the active roles of the bud topography in the sorting and migration machinery of key signalling proteins involved in membrane budding.

Ryu, Yong-Sang; Lee, In-Ho; Suh, Jeng-Hun; Park, Seung Chul; Oh, Soojung; Jordan, Luke R.; Wittenberg, Nathan J.; Oh, Sang-Hyun; Jeon, Noo Li; Lee, Byoungho; Parikh, Atul N.; Lee, Sin-Doo

2014-07-01

203

Reconstituting ring-rafts in bud-mimicking topography of model membranes  

PubMed Central

During vesicular trafficking and release of enveloped viruses, the budding and fission processes dynamically remodel the donor cell membrane in a protein- or a lipid-mediated manner. In all cases, in addition to the generation or relief of the curvature stress, the buds recruit specific lipids and proteins from the donor membrane through restricted diffusion for the development of a ring-type raft domain of closed topology. Here, by reconstituting the bud topography in a model membrane, we demonstrate the preferential localization of cholesterol- and sphingomyelin-enriched microdomains in the collar band of the bud-neck interfaced with the donor membrane. The geometrical approach to the recapitulation of the dynamic membrane reorganization, resulting from the local radii of curvatures from nanometre-to-micrometre scales, offers important clues for understanding the active roles of the bud topography in the sorting and migration machinery of key signalling proteins involved in membrane budding. PMID:25058275

Ryu, Yong-Sang; Lee, In-Ho; Suh, Jeng-Hun; Park, Seung Chul; Oh, Soojung; Jordan, Luke R.; Wittenberg, Nathan J.; Oh, Sang-Hyun; Jeon, Noo Li; Lee, Byoungho; Parikh, Atul N.; Lee, Sin-Doo

2014-01-01

204

Antarctic hypsometry and the source of East Antarctica's anomalous topography  

NASA Astrophysics Data System (ADS)

The re-examined hypsometry of Antarctica based on BEDMAP2 data reveals deglaciated modal elevations of ~-450 m and ~650 m for West and East Antarctica, respectively. Although the East Antarctic modal elevation is 300 m lower than the original measurement, it still renders the plateau topographically anomalous by ~400-600 m with respect to the existing global continental modal elevation estimates of 87 m and 250 m. Superimposed on the plateau are the Gamburtsev Subglacial Mountains, the Dronning Maud Land Mountains and the Vostok Highlands with modal elevations ~400 m in excess of the East Antarctic mode. To ascertain whether East Antarctica's anomalous topography can be attributed to Airy-type crustal compensation, a continental-scale crustal thickness model is derived from the inversion of GOCO03S satellite gravity data constrained by seismic crustal thickness measurements. The average crustal thickness of East Antarctica is ~40 km (for West Antarctica ~24 km), a value typical of Archean shields. While crustal thickening to >50 km locally beneath the Gamburtsev Subglacial Mountains and Dronning Maud Land can account for their differential modal elevation above the plateau, the evidently typical Archean crust elsewhere across East Antarctica offers no suggestion of crustal-level continental-scale support for the broader plateau. The plateau of southern Africa offers a tectonic analogue: Like East Antarctica, the lithosphere is largely Archean and cratonic, the crust is of typical shield thickness, there is no obvious Cenozoic tectonism and the upper mantle does not appear to be unduly perturbed. The relative accessibility of the African continent, meanwhile, has led to conclusive imaging of large-scale perturbations in the lower mantle beneath the southern African plateau pointing to dynamic, rather that isostatic, support of the associated long wavelength topography. While several global seismic tomography models infer somewhat anomalously slow lower mantle structure beneath Antarctica, the resolution presently offered by such models in this region is poor. That said, the apparent absence of crustal-level continental-scale support for the East Antarctic plateau coupled with the fact that the underlying upper mantle does not appear unduly anomalous suggest, by analogy with southern Africa, lower mantle generated epeirogeny as a likely explanation for the anomalous topography. The incorporation of data from the Antarctic seismic deployments of recent years in the next generation of global tomography models should resolve the issue.

O'Donnell, J.; Nyblade, A.

2013-12-01

205

Swath Measurements of Ice Sheet Bottom Topography and Radar Reflectivity  

NASA Astrophysics Data System (ADS)

Ice sheet thickness is a fundamental measurement for understanding the dynamics of large ice sheets (terrestrial or extraterrestrial). Radar is the primary tool used to measure ice thickness but a major challenge is accurately measuring the arrival time of the basal echo in the presence of surface clutter, which may arise from processes such as wind driven deposition and erosion or crevassing. Essentially, the basal echo strength, which is weak because of attenuation through the ice, becomes comparable to the surface scattering signal even though the coincident surface return comes from a large, off-nadir angle. During the past 4 years, we explored three surface clutter rejection techniques and applied them to data collected with 150/450 MHz radars operated from aircraft over the Greenland Ice Sheet. We also investigated how the techniques could be used to go beyond nadir sounding of ice sheets and, when operated used with broad-beam antennas, could successfully acquire 3-dimensional intensity images of the ice sheet base. In this paper, we describe experiments to image the ice sheet base using: synthetic aperture radar (SAR) interferogram filtering; SAR tomography; and beam steering. For the case of a broad beam antenna array, we show that interferograms filtering provides the highest quality topographic data from both the left and right sides of the aircraft but only under optimal conditions. We show that a beam-steering/radar tomography hybrid algorithm provides the most robust topography and also yields an intensity map. We provide example topographies for the base of the Greenland Ice Sheet and suggest how the approach could be used for future sounding of extraterrestrial ice. The research described in this paper was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under a grant from the National Aeronautics and Space Administration. 3-d radar image of the base of the ice sheet. Scene is an orthorectified mosaic located just south of the main Jacobshavn Drainage Channel

Freeman, A.; Gogineni, P. S.; Jezek, K. C.; Rodriguez, E.; Wu, X.

2009-12-01

206

X-Ray Stress Topography of Thin Films on Germanium and Silicon  

Microsoft Academic Search

X-ray stress topography of thin films deposited on single-crystal substrates is established. This method permits a nondestructive rapid analysis of the stress environment of film-crystal interfaces. It is based on dynamical diffraction phenomena that occur at such interfaces. This technique is principally useful for the measurement of the sign of the stress in film and?or substrate. It is used to

G. H. Schwuttke; J. K. Howard

1968-01-01

207

X-Ray Topography of Magnetic Domains in Iron Whisker Crystals  

Microsoft Academic Search

Magnetic domains in well annealed [001] whisker crystals have been studied by X-ray topography. The three-dimensional shape of the rectangular domain observed by the powder pattern technique was found to be a cuboid. Qualitative explanation is given to the image contrast of 90° domain walls by the dynamical theory of X-ray diffraction in distorted crystals. The lattice distortion around the

Sigemaro Nagakura; Yoshinori Chikaura

1971-01-01

208

Measurement of the topography of human cadaver lenses using the PAR corneal topography system  

NASA Astrophysics Data System (ADS)

To measure the radius of curvature and asphericity of the anterior and posterior surfaces of crystalline lenses of human Eye-Bank eyes using the PAR Corneal Topography System. The measured values will be used in an optical model of the eye for lens refilling procedures.

Fernandez, Viviana; Manns, Fabrice; Zipper, Stanley; Sandadi, Samith; Hamaoui, Marie; Tahi, Hassan; Ho, Arthur; Parel, Jean-Marie A.

2001-06-01

209

A puzzle about the Scandinavian topography  

NASA Astrophysics Data System (ADS)

In this contribution we analyze the topography of Scandinavia with a method recently used to assess the age and the stage of topographical evolution of the Alps (Hergarten, Wagner & Stüwe, EPSL 297:453, 2010). The method considers the mean (channel) slope at fixed catchment size as a function of the elevation. For continental Europe (without Scandinavia) we found a linear relationship without any offset up to elevations of several hundred meters, which means that slope is directly proportional to elevation. This relationship also holds for smaller parts of Europe such as the region directly draining to the Atlantic Ocean or the Mediterranean region, although the reason for this phenomenon remains unclear. In contrast, the region of Norway draining to the Atlantic Ocean west of Norway's southernmost point shows a different behavior. The slope-elevation relation follows is a straight line, too, but with a significant offset of about 500 m. Extrapolating this relation towards negative elevations suggests that zero slope would be achieved about 500 m below sea level. A possible interpretation of this vertical shift in topography might be that 500 m of glacial subsidence are still left at Norway's coast of the Atlantic Ocean. But on the other hand, analyzing the part of Scandinavia draining to Skagerrak, Kattegat and Baltic Sea yields a linear slope-elevation relationship without any vertical shift, although this region should include the center of Scandinavia's glacial subsidence.

Hergarten, S.; Stüwe, K.

2012-04-01

210

Retrieving lunar topography from multispectral LROC images  

NASA Astrophysics Data System (ADS)

A technique for retrieving information about the lunar topography from any individual multispectral LROC Wide Angle Camera (WAC) image has been developed. This technology is possible, since images acquired at different wavelengths correspond to different viewing angles and the influence of color differences between the images on the parallax assessments is small. This method provides the precision of Digital Elevation Models (DEMs) comparable to the global lunar 100 m raster DTM retrieved from the LROC WAC stereo model (GLD100). It potentially allows one to obtain maps of the elevations with better horizontal resolution than those of the GLD100. An empirical model of the distortion for LROC WAC has been developed and used for correction of the initial WAC images. In contrast to the standard pre-flight model, our model allows for compensation of the radial distortion, decentering the optics, and tilt of the CCD array almost fully. The DEMs obtained using our approach exhibit real morphological details in some cases that are invisible in GLD100 maps. Thus, our method suggests additional independent information about the lunar topography. The fact that our elevation maps have the same projection as the initial images allows valid corrections of these images to account for topographic effects (i. e. orthorectification) in contrast to the use of the GLD100 that may have slightly different coordinates referencing in comparison to individual WAC images.

Korokhin, Viktor V.; Velikodsky, Yuri I.; Shalygin, Eugene V.; Shkuratov, Yuriy G.; Kaydash, Vadym G.; Videen, Gorden

2014-03-01

211

Analysis Of Scoliosis By Back Shape Topography  

NASA Astrophysics Data System (ADS)

The use of surface topography for the assessment of scoliotic deformity in the clinic depends firstly on the quality of measures which reliably characterise deformity of the back, and secondly on the ease and speed with which these measures can be applied. A method of analysis of back shape measurements is presented which can be applied to any topographic measurement system. Measures presented are substantially independent of minor changes in the patient's posture in rotation and flexion from one clinic to the next, and yet sensitive enough to indicate significant improvement or degeneration of the disease. The presentation shows (1) horizontal cross-sections at ten levels up the back from sacrum to vertebra prominens, (2) angles of rotation of the surface over a small region about the spine, (3) three vertical profiles following the line of the spine, and (4) measures of maximum kyphosis and lordosis. Dependence on the operator has been reduced to a minimum. Extreme care in positioning the patient is unnecessary and those spinous processes which are easily palpable, the vertebra prominens and the two dimples over the posterior superior iliac spines are marked. Analysis proceeds entirely automatically once the basic shape data have been supplied. Applications of the technique to indirect moire topography and a television topographic measurement system are described.

Turner-Smith, Alan R.; Harris, John D.

1983-07-01

212

Interpreting layer thickness advection in terms of eddy-topography interaction  

NASA Astrophysics Data System (ADS)

A parameterization for the spatial pattern of the eddy induced thickness advection parameter estimated from a dynamically consistent data assimilation procedure is presented. Values of the thickness advection parameter are predominantly negative (positive) over seamounts, and positive (negative) over the deep ocean in the southern (northern) hemisphere along strong currents; its magnitude is large at high latitudes but low in the tropical regions. Those characteristics motivate a parameterization based on the Coriolis parameter, the bottom depth and an eddy length scale. As a parameterization for an eddy streamfunction, the associated bolus velocities advect density anti-cyclonically (cyclonically) around seamounts (troughs). Although the parameterization has the same form as Holloway’s streamfunction for the Neptune effect, and is also related to eddy-topography interactions, Holloway’s streamfunction is in contrast applied to the momentum equation. The parameterization is independently confirmed by the flux-mean gradient relation from the output of a high resolution model. The effect of the proposed scheme is investigated using a channel model with idealized bottom topographies and a global ocean circulation model with realistic bottom topography. In agreement with the high resolution model, our scheme generates cold (warm) domes and cyclonic circulations over seamounts (troughs), which is consistent with the eddy movement in presence of the topographic ? effect. This provides a different mechanism for eddy-topography interaction than the Neptune effect, which generates circulations of opposing sign.

Liu, Chuanyu; Köhl, Armin; Stammer, Detlef

2014-09-01

213

Hydrothermal circulation in fault slots with topography  

NASA Astrophysics Data System (ADS)

There are numerous cases where the circulation of hydrothermal fluid is likely to be confined within a permeable fault slot. Examples are (1) the Lost City Hydrothermal Field (LCHF) at 30 N in the Atlantic, which is likely to be controlled by large E-W faults related to the Atlantis transform fault and mass wasting on the southern wall of the Atlantis Massif, and (2) large normal faults bounding the Hess Deep rift in the East Pacific, which contain intense hydrothermal metamorphic assemblages in lower crustal gabbros formed at 200-350 ° C. This type of circulation could occur anywhere where steep faults cut the oceanic crust, including large near-axis normal faults, transform faults and faults at subduction bend zones, and could be the major way in which the upper mantle and lower crust are hydrated. It is therefore important to constrain the controls on temperature conditions of alteration and hence mineral assemblages. Previous 2-D modelling of the LCHF shows that seafloor topography and permeability structure combine together to localise the field near the highest point of the Atlantis Massif. Our new models are 3-D, based on a 10km cube with seafloor topography of ~ 2km affecting both the fault slot and impermeable wall rocks. We have used Comsol multiphysics in this modelling, with a constant basal heatflow corresponding to the near conductive thermal gradient measured in IODP Hole 1309D, 5km north of the LCHF, and a constant temperature seafloor boundary condition. The wall rocks of the slot have a permeability of 10-17 m2 while permeability in the slot is varied between 10-14 and 10-15 m2. Initial conditions are a conductive thermal structure corresponding to the basal heatflow at steady state. Generic models not based on any particular known topography quickly stabilise a hydrothermal system in the fault slot with a single upflow zone close to the model edge with highest topography. In models with a depth of circulation in the fault slot of about 6 km, after an initial period of higher temperature venting which removes heat from the initial condition, venting temperature is approximately 200 ° C with a permeability of 3x10-15 m2. This falls to about 170 ° C with a permeability of 5x10-15 m2. Temperatures can be reduced by restricting the depth of hydrothermal circulation. These temperatures correspond to prehnite-chlorite assemblages seen in fault rocks at Hess Deep, but are higher than those observed at the LCHF. Work is continuing to vary permeability, fault slot geometry and topography to better match the conditions in the Atlantis Massif, and to model the effects of dyke intrusion into the fault zone as observed at Hess Deep.

Titarenko, Sofya; McCaig, Andrew

2014-05-01

214

Imaging defects in macromolecular crystals with x-ray topography  

Microsoft Academic Search

X-ray topography is a well established technique to characterize growth or process induced defects. As a characterization tool for crystal growers X-ray topography is probably the simplest non destructive imaging technique available. However, only recently it has been applied to image growth induced defects in protein crystals.We will discuss the use of white and monochromatic x-ray topography methods in understanding

V. Stojanoff; D. P. Siddons

1996-01-01

215

Absolute Measure of Local Chirality and the Chiral Polarization Scale of the QCD Vacuum  

E-print Network

The use of the absolute measure of local chirality is championed since it has a uniform distribution for randomly reshuffled chiral components so that any deviations from uniformity in the associated "X-distribution" are directly attributable to QCD-induced dynamics. We observe a transition in the qualitative behavior of this absolute X-distribution of low-lying eigenmodes which, we propose, defines a chiral polarization scale of the QCD vacuum.

Andrei Alexandru; Terrence Draper; Ivan Horváth; Thomas Streuer

2010-10-26

216

Magnifying absolute instruments for optically homogeneous regions  

NASA Astrophysics Data System (ADS)

We propose a class of magnifying absolute optical instruments with a positive isotropic refractive index. They create magnified stigmatic images, either virtual or real, of optically homogeneous three-dimensional spatial regions within geometrical optics.

Tyc, Tomáš

2011-09-01

217

Absolute vs. intensity-based emission caps  

E-print Network

Cap-and-trade systems limit emissions to some pre-specified absolute quantity. Intensity-based limits, that restrict emissions to some pre-specified rate relative to input or output, are much more widely used in environmental ...

Ellerman, A. Denny.

218

The Simplicity Argument and Absolute Morality  

ERIC Educational Resources Information Center

In this paper the author has maintained that there is a similarity of thought to be found in the writings of Cudworth, Emerson, and Husserl in his investigation of an absolute system of morality. (Author/RK)

Mijuskovic, Ben

1975-01-01

219

STS-99 Shuttle Radar Topography Mission Stability and Control  

NASA Technical Reports Server (NTRS)

The Shuttle Radar Topography Mission (SRTM) flew aboard Space Shuttle Endeavor February 2000 and used interferometry to map 80% of the Earth's landmass. SRTM employed a 200-foot deployable mast structure to extend a second antenna away from the main antenna located in the Shuttle payload bay. Mapping requirements demanded precision pointing and orbital trajectories from the Shuttle on-orbit Flight Control System (PCS). Mast structural dynamics interaction with the FCS impacted stability and performance of the autopilot for attitude maneuvers and pointing during mapping operations. A damper system added to ensure that mast tip motion remained with in the limits of the outboard antenna tracking system while mapping also helped to mitigate structural dynamic interaction with the FCS autopilot. Late changes made to the payload damper system, which actually failed on-orbit, required a redesign and verification of the FCS autopilot filtering schemes necessary to ensure rotational control stability. In-flight measurements using three sensors were used to validate models and gauge the accuracy and robustness of the pre-mission notch filter design.

Hamelin, Jennifer L.; Jackson, Mark C.; Kirchwey, Christopher B.; Pileggi, Roberto A.

2001-01-01

220

A Cryogenic Radiometer for Absolute Radiometric Measurements  

Microsoft Academic Search

The adoption in 1979 of a new definition of the candela, which permitted a detector-based approach to the realization of the unit, has emphasized the importance of high-accuracy absolute radiation detectors. This paper describes a new electrical-substitution absolute radiometer operating at 5 K, based on a standard commercial helium cryostat, which has been developed at NPL for optical radiant-power measurements.

J E Martin; N P Fox; P J Key

1985-01-01

221

MSTAR: a submicrometer absolute metrology system.  

PubMed

The Modulation Sideband Technology for Absolute Ranging (MSTAR) sensor permits absolute distance measurement with subnanometer accuracy, an improvement of 4 orders of magnitude over current techniques. The system uses fast phase modulators to resolve the integer cycle ambiguity of standard interferometers. The concept is described and demonstrated over target distances up to 1 m. The design can be extended to kilometer-scale separations. PMID:12816236

Lay, O P; Dubovitsky, S; Peters, R D; Burger, J P; Ahn, S W; Steier, W H; Fetterman, H R; Chang, Y

2003-06-01

222

State estimation and absolute image registration for geosynchronous satellites  

NASA Technical Reports Server (NTRS)

Spacecraft state estimation and the absolute registration of Earth images acquired by cameras onboard geosynchronous satellites are described. The basic data type of the procedure consists of line and element numbers of image points called landmarks whose geodetic coordinates, relative to United States Geodetic Survey topographic maps, are known. A conventional least squares process is used to estimate navigational parameters and camera pointing biases from observed minus computed landmark line and element numbers. These estimated parameters along with orbit and attitude dynamic models are used to register images, using an automated grey level correlation technique, inside the span represented by the landmark data. In addition, the dynamic models can be employed to register images outside of the data span in a near real time mode. An important application of this mode is in support of meteorological studies where rapid data reduction is required for the rapid tracking and predicting of dynamic phenomena.

Nankervis, R.; Koch, D. W.; Sielski, H.

1980-01-01

223

Determination of ¹?N-incorporation into plant proteins and their absolute quantitation: a new tool to study nitrogen flux dynamics and protein pool sizes elicited by plant-herbivore interactions.  

PubMed

Herbivory leads to changes in the allocation of nitrogen among different pools and tissues; however, a detailed quantitative analysis of these changes has been lacking. Here, we demonstrate that a mass spectrometric data-independent acquisition approach known as LC-MS(E), combined with a novel algorithm to quantify heavy atom enrichment in peptides, is able to quantify elicited changes in protein amounts and (15)N flux in a high throughput manner. The reliable identification/quantitation of rabbit phosphorylase b protein spiked into leaf protein extract was achieved. The linear dynamic range, reproducibility of technical and biological replicates, and differences between measured and expected (15)N-incorporation into the small (SSU) and large (LSU) subunits of ribulose-1,5-bisphosphate-carboxylase/oxygenase (RuBisCO) and RuBisCO activase 2 (RCA2) of Nicotiana attenuata plants grown in hydroponic culture at different known concentrations of (15)N-labeled nitrate were used to further evaluate the procedure. The utility of the method for whole-plant studies in ecologically realistic contexts was demonstrated by using (15)N-pulse protocols on plants growing in soil under unknown (15)N-incorporation levels. Additionally, we quantified the amounts of lipoxygenase 2 (LOX2) protein, an enzyme important in antiherbivore defense responses, demonstrating that the approach allows for in-depth quantitative proteomics and (15)N flux analyses of the metabolic dynamics elicited during plant-herbivore interactions. PMID:22905865

Ullmann-Zeunert, Lynn; Muck, Alexander; Wielsch, Natalie; Hufsky, Franziska; Stanton, Mariana A; Bartram, Stefan; Böcker, Sebastian; Baldwin, Ian T; Groten, Karin; Svatoš, Aleš

2012-10-01

224

Absolute entropy and free energy of fluids using the hypothetical scanning method. I. Calculation of transition probabilities from local grand  

E-print Network

Absolute entropy and free energy of fluids using the hypothetical scanning method. I. Calculation the absolute entropy and free energy from a Boltzmann sample generated by Monte Carlo, molecular dynamics for the free energy. We demonstrate that very good results for the entropy and the free energy can be obtained

Meirovitch, Hagai

225

Projecting picosecond lattice dynamics through x-ray topography  

Microsoft Academic Search

A method for time-resolved x-ray diffraction studies has been demonstrated. As a test case, coherent acoustic phonon propagation into crystalline InSb is observed using a laser plasma x-ray source. An extended x-ray topogram of the semiconductor's surface was projected onto a high spatial resolution x-ray detector and acoustic phonons were excited by rapidly heating the crystal's surface with a femtosecond

O. Synnergren; M. Harbst; T. Missalla; J. Larssona; G. Katona; R. Neutze; R. Wouts

2002-01-01

226

The Influence of Topography on Volatile Transport  

NASA Astrophysics Data System (ADS)

Topography can exert important influences on volatile transport on bodies, such as Pluto and Triton, with global atmospheres supported by vapor pressure equilibrium with volatile frost on the surface. First, because local energy balance depends on the illumination angle, volatile frost will preferentially sublime from (condense on) areas tilted towards (away from) the Sun, as has been previously modelled at small spatial scales [e.g. 1]. Topographic features can also cause a completely different kind of vertical volatile transport resulting from the decrease in atmospheric pressure with altitude. On Pluto and Triton the sublimation flux from a topographic feature approximately one km high is comparable to the seasonal or inter-hemispheric sublimation flux (1 g/cm2^/year). To the extent that seasonal transport influences the distribution of volatile ices (and related characteristics such as albedo, emissivity, reflectance spectrum), topography-driven transport will exert a comparable influence around features a km or more above (or below) the global mean altitude of the frost deposits. This implies that in addition to there being a global "frost temperature" (defined by the temperature at which the frost vapor pressure equals the atmospheric pressure), there is a "frost altitude" (defined by the globally-averaged altitude of all the volatile frost). The sense of topography-driven volatile transport is to denude high areas. Consider two frost patches with equilibrium temperatures equal to the frost temperature, but at different altitudes. The high(low)-altitude patch is in contact with a lower(higher)-pressure atmosphere due to the e^(-z/H) dependence of atmospheric pressure. If the high(low)-altitude patch is above(below) the frost altitude, frost will sublime from (condense on) the high (low) frost patch, resulting in net downhill transport. We present models for the combined effects of illumination and altitude on frost transport rates for simple topographic features and discuss how these may influence the appearance of Pluto's surface as it will be seen by the New Horizons spacecraft in July 2015. [1] Yelle (1992) Science 255, 1553-1555.

Stansberry, John A.; Grundy, Will; Young, Leslie

2014-11-01

227

Verification of Geosat sea surface topography in the Gulf Stream extension with surface drifting buoys and hydrographic measurements  

Microsoft Academic Search

Altimeter data from Geosat have been analyzed in the Gulf Stream extension area. Horizontal maps of the sea surface height anomaly relative to an annual mean for various 17-day intervals were constructed using an objective mapping procedure. The mean sea level was approximated by the dynamic topography from climatological hydrographic data. Geostrophic surface velocities derived from the composite maps (mean

J. Willebrand; R. H. Käse; D. Stammer; H.-H. Hinrichsen; W. Krauss

1990-01-01

228

EAARL submarine topography: Biscayne National Park  

USGS Publications Warehouse

This lidar-derived submarine topography map was produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs for the purposes of habitat mapping, ecological monitoring, change detection, and event assessment (for example: bleaching, hurricanes, disease outbreaks). As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring water depth and conducting cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to managers of coastal tropical habitats.

Brock, John C.; Wright, C. Wayne; Patterson, Matt; Nayegandhi, Amar; Patterson, Judd; Harris, Melanie S.; Mosher, Lance

2006-01-01

229

Architecture and development of olivocerebellar circuit topography  

PubMed Central

The cerebellum has a simple tri-laminar structure that is comprised of relatively few cell types. Yet, its internal micro-circuitry is anatomically, biochemically, and functionally complex. The most striking feature of cerebellar circuit complexity is its compartmentalized topography. Each cell type within the cerebellar cortex is organized into an exquisite map; molecular expression patterns, dendrite projections, and axon terminal fields divide the medial-lateral axis of the cerebellum into topographic sagittal zones. Here, we discuss the mechanisms that establish zones and highlight how gene expression and neural activity contribute to cerebellar pattern formation. We focus on the olivocerebellar system because its developmental mechanisms are becoming clear, its topographic termination patterns are very precise, and its contribution to zonal function is debated. This review deconstructs the architecture and development of the olivocerebellar pathway to provide an update on how brain circuit maps form and function. PMID:23293588

Reeber, Stacey L.; White, Joshua J.; George-Jones, Nicholas A.; Sillitoe, Roy V.

2013-01-01

230

Assimilation of altimeter topography into oceanic models  

NASA Technical Reports Server (NTRS)

The primary goals of the authors are to build an intuition for assimilation techniques and to investigate the impact of variable altimeter topography on simple or complex oceanic models. In particular, applying various techniques and sensitivity studies to model and data constraints plays a key role. We are starting to use quasi-geostrophic, semigeostrophic, and primitive-equation (PE) models and to test the schemes in regions of interest to the World Ocean Circulation Experiment (WOCE), as well as in the northeast Atlantic and the Mediterranean. The impact of scatterometer wind forcing on the results is also investigated. The use of Geosat, European Remote Sensing satellite (ERS-1), and TOPEX/POSEIDON altimetry data is crucial in fine tuning the models and schemes to the selected areas of interest.

Demey, Pierre; Menard, Yves; Pinardi, Nadia; Schroeter, J.; Verron, J.

1991-01-01

231

Australian topography from Seasat overland altimetry  

NASA Technical Reports Server (NTRS)

Retracking of overland returns from the Seasat altimeter using algorithms originally developed for recovering elevations over ice has led to the successful recovery of high quality continental topography over Australia and other continents. Cross-over analysis both before and after orbit adjustment shows the altimetric data over land to have a 2-3 m quality. Direct comparison of gridded Seasat data with surface data re-averaged in the same way shows excellent agreement except where Seasat data are sparse, due either to poor track spacing or to dropouts caused by loss of tracker lock over steeply sloping ground. These results suggest that useful topographic data can be derived from Seasat and the more recent Geosat altimeters for parts of the world where surface data are few or of poor quality.

Frey, Herbert; Brenner, Anita C.

1990-01-01

232

Temporal and spatial distribution of exhumed topography  

NASA Technical Reports Server (NTRS)

Perhaps the greatest chance for exhumation, or burial, of a landscape by terrestrial processes exists near the boundaries of the climatic belts. In the Southern Hemisphere, there is comparatively little land area within Budel's zone of extra-tropical valley formation, which contains most of the examples of exhumed topography in the Northern Hemisphere. The only examples of resurrected landforms that occur within Budel's tropical zone are located near the boundary of this zone, where climate may have changed during the Pleistocene. The ages of exhumed landforms sampled are not equally distributed through geologic time. Most of the exhumed features were created either during the Precambrian or the Tertiary periods which are commonly cited as episodes of significant landform development.

Rhodes, D. D.

1984-01-01

233

Episodic growth of topography in eastern Tibet  

NASA Astrophysics Data System (ADS)

High topography associated with the eastern portions of the Tibetan Plateau is thought to have developed as eastward flow of deep crust from beneath central Tibet drove crustal thickening and attendant surface uplift along the periphery of the plateau. The onset of rapid Late Miocene exhumation (ca. 10-15 Ma) in deep canyons of eastern Tibet is inferred to herald surface uplift which enabled rapid fluvial incision and the development of high topographic relief. Although consistent with geophysical data, this model struggles to explain the timing and amount of Cenozoic shortening adjacent to the Sichuan Basin. Here we report cooling histories of rocks currently exposed along a ~3 km vertical section adjacent to the Sichuan Basin derived from multiple low-temperature thermochronologic systems including apatite and zircon fission-track and (U-Th)/He. Our results reveal that this margin of the plateau was subject to slow, steady exhumation during early Cenozoic time, requiring that limited topographic relief (<1000m) was present prior to initial collision of India and Asia. Moreover, thermal models of exhumation-driven cooling demonstrate that subsequent exhumation of >10 km occurred in two temporally-distinct episodes, during Oligocene (~30-25 Ma) and Late Miocene (~10-15 Ma) time, separated by a hiatus of at least 10 Ma. These results challenge the notion that the plateau in eastern Tibet developed as a singular consequence of lower crustal flow. Rather, our findings require a punctuated history of mountain building that potentially reconciles conflicting models for relative roles of upper crustal shortening and lower crustal flow in the development of topography adjacent to the Sichuan Basin.

Kirby, E.; Furlong, K.; Wang, E.; Shi, X.; van Soest, M.; Xu, G.; Kamp, P.; Hodges, K.

2012-04-01

234

Bedrock topography beneath the Red Lake peatlands  

SciTech Connect

Detailed hydrologic investigations of peat landforms in the Red Lake Peatlands have revealed that groundwater flow is significantly related to the type of landform and vegetation community present at a given site. Hydrogeologic modeling of shallow groundwater systems suggests that bedrock topography is an important, perhaps the vital, boundary condition controlling groundwater flow. Determination of depth to bedrock beneath different peat landforms is necessary to test the hydrogeologic models and obtain a better understanding of the processes which produce them. Direct determination of bedrock depth in peatlands is hampered by the difficult conditions and high costs of boring. In addition, environmental impacts from boring activities would probably be substantial in these sensitive ecosystems. Shallow seismic methods appear to be the most promising approach to obtain the necessary data. Unfortunately the 2+ meters of peat covering Lake Agassiz sediments overlying the bedrock is not only a poor substrate for geophone emplacement, but is a strong attenuator of seismic waves. These difficulties have been overcome by constructing a tool which allows the geophones to be emplaced beneath the peat and into the top of the sediments. The shotgun cartridge source is also located beneath the peat. This combination results in very good seismic records, far better than those possible with surface sources and geophones. The results from a preliminary survey along a 600m line show that there are significant variations in bedrock topography below the peat. In a distance of less than 500m, depth to bedrock changes by about 30%, from about 55m to about 40m. This is similar to variations indicated by the models.

Miller, P.; Shaw, G.H. (Union Coll., Schenectady, NY (United States). Geology Dept.); Glaser, P. (Univ. of Minnesota, Minneapolis, MN (United States). Limnological Research Center); Siegel, D. (Syracuse Univ., NY (United States). Dept. of Geology)

1992-01-01

235

Surface Water and Ocean Topography (SWOT) mission  

NASA Astrophysics Data System (ADS)

The Surface Water Ocean Topography (SWOT) mission was recommended in 2007 by the National Research Council's Decadal Survey, "Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond", for implementation by NASA. The SWOT mission is a partnership between two communities, the physical oceanography and the hydrology, to share high vertical accuracy and high spatial resolution topography data produced by the science payload, principally a Ka-band radar Interferometer (KaRIn). The SWOT payload also includes a precision orbit determination system consisting of GPS and DORIS receivers, a Laser Retro-reflector Assembly (LRA), a Jason-class nadir radar altimeter, and a JASON-class radiometer for tropospheric path delay corrections. The SWOT mission will provide large-scale data sets of ocean sea-surface height resolving scales of 15km and larger, allowing the characterization of ocean mesoscale and submesoscale circulation. The SWOT mission will also provide measurements of water storage changes in terrestrial surface water bodies and estimates of discharge in large (wider than 100m) rivers globally. The SWOT measurements will provide a key complement to other NASA spaceborne global measurements of the water cycle measurements by directly measuring the surface water (lakes, reservoirs, rivers, and wetlands) component of the water cycle. The SWOT mission is an international partnership between NASA and the Centre National d'Etudes Spatiales (CNES). The Canadian Space Agency (CSA) is also expected to contribute to the mission. SWOT is currently nearing entry to Formulation (Phase A). Its launch is targeted for October 2020.

Neeck, Steven P.; Lindstrom, Eric J.; Vaze, Parag V.; Fu, Lee-Lueng

2012-09-01

236

Representation of topography in spectral climate models and its effect on simulated precipitation  

SciTech Connect

Spectral climate models are distinguished by their representation of variables as finite sums of spherical harmonics, with coefficients computed by an orthogonal projection of the variables onto the spherical harmonics. Representing the surface elevation in this manner results in its contamination by Gibbs-like truncation artifacts, which appear as spurious valleys and mountain chains in the topography. These {open_quotes}Gibbs ripples{close_quotes} are present in the surface topographies of spectral climate models from a number of research institutions. Integrations of the Geophysical Fluid Dynamics Laboratory (GFDL) climate model over a range of horizontal resolutions indicate that the Gibbs ripples lead to spurious, small-scale extrema in the spatial distribution of precipitation. This {open_quotes}cellular precipitation pathology{close_quotes} becomes more pronounced with increasing horizontal resolution, causing a deterioration in the fidelity of simulated precipitation in higher resolution models. A method is described for reducing the Gibbs ripples that occur when making an incomplete spherical harmonic expansion of the topography. The new spherical harmonic representations of topography are formed by fitting a nonuniform spherical smoothing spline to geodetic data and found by solving a fixed-point problem. This regularization technique results in less distortion of features such as mountain height and continental boundaries than previous smoothing methods. These new expansions of the topography, when used as a lower boundary surface in the GFDL climate model, substantially diminish the cellular precipitation pathology and produce markedly more realistic simulations of precipitation. These developments make the prospect of using higher resolution spectral models for studies of regional hydrologic climate more attractive. 34 refs., 11 figs., 1 tab.

Lindberg, C.; Broccoli, A.J. [Princeton Univ., NJ (United States)] [Princeton Univ., NJ (United States)

1996-11-01

237

Jasminum flexile flower absolute from India--a detailed comparison with three other jasmine absolutes.  

PubMed

Jasminum flexile flower absolute from the south of India and the corresponding vacuum headspace (VHS) sample of the absolute were analyzed using GC and GC-MS. Three other commercially available Indian jasmine absolutes from the species: J. sambac, J. officinale subsp. grandiflorum, and J. auriculatum and the respective VHS samples were used for comparison purposes. One hundred and twenty-one compounds were characterized in J. flexile flower absolute, with methyl linolate, benzyl salicylate, benzyl benzoate, (2E,6E)-farnesol, and benzyl acetate as the main constituents. A detailed olfactory evaluation was also performed. PMID:19831037

Braun, Norbert A; Kohlenberg, Birgit; Sim, Sherina; Meier, Manfred; Hammerschmidt, Franz-Josef

2009-09-01

238

Geophysical implications of the longwavelength topography of the Saturnian satellites  

E-print Network

Geophysical implications of the longwavelength topography of the Saturnian satellites F. Nimmo,1 B may also play a role in determining the variance spectra of some bodies. Citation: Nimmo, F., B. G thickness variations likely cause the observed longwavelength topography on Titan [Nimmo and Bills, 2010

Nimmo, Francis

239

Surface mining simulator for application in steep slope topography  

Microsoft Academic Search

A surface mining simulator has been developed for application in steep slope topography. The simulator is designed to model haulback mining, as commonly practiced in Appalachian areas, and is applicable to contour mining and mountain top removal mining. Its primary use will be comparison of alternative overburden handling plans. Major inputs include pre-mining topography as a sequence of mining block

C. E. Zipper; A. Chakraborty; E. Topuz; W. L. Daniels

1985-01-01

240

X-ray topography and precision diffractometry of semiconducting materials  

Microsoft Academic Search

The application of double axis x-ray diffractometry to the nondestructive evaluation of semiconducting materials is reviewed. Particular emphasis is placed on the data which can be obtained in standard geometry from commercially available instruments. Following a brief summary of the state of the art, x-ray topography techniques are discussed in relation to their application for quality control. Section topography is

B. K. Tanner

1989-01-01

241

Rigorous topography simulation of contamination to defect transformation  

Microsoft Academic Search

Particulate contamination deposited on silicon wafers is typically the dominant reason for yield loss in VLSI manufacturing. The transformation of contaminating particles into defects and then electrical faults is a very complex process which depends on the defect location, size, material and the underlying IC topography. Rigorous 2D and 3D topography simulators based on the waveguide method have been developed

Xiaolei Li; Andrzej Strojwas; A. Swecker; L. Milor; Yung-Tao Linb

1997-01-01

242

Cokriging surface elevation and seismic refraction data for bedrock topography  

SciTech Connect

Analysis of seismic refraction data collected at a proposed site of the Advanced Neutron Source (ANS) Facility showed a strong correlation between surface and bedrock topography. By combining seismically determined bedrock elevation data with surface elevation data using cokriging, we were able to significantly improve our map of bedrock topography without collecting additional seismic data.

Nyquist, J.E.; Doll, W.E. [Oak Ridge National Lab., TN (United States); Davis, R.K. [Automated Sciences Group, Inc., Oak Ridge, TN (United States); Hopkins, R.A. [Marrich, Inc., Knoxville, TN (United States)

1992-11-01

243

Cokriging surface elevation and seismic refraction data for bedrock topography  

SciTech Connect

Analysis of seismic refraction data collected at a proposed site of the Advanced Neutron Source (ANS) Facility showed a strong correlation between surface and bedrock topography. By combining seismically determined bedrock elevation data with surface elevation data using cokriging, we were able to significantly improve our map of bedrock topography without collecting additional seismic data.

Nyquist, J.E.; Doll, W.E. (Oak Ridge National Lab., TN (United States)); Davis, R.K. (Automated Sciences Group, Inc., Oak Ridge, TN (United States)); Hopkins, R.A. (Marrich, Inc., Knoxville, TN (United States))

1992-01-01

244

Characterizing topography-induced contrast in photoelectron emission microscopy  

Microsoft Academic Search

As part of an ongoing study to quantify the imaging response of the photoelectron emission microscope (PEEM), we have investigated the effect of sample topography on PEEM contrast. Both numerical simulations and well characterized samples were used to investigate topography-induced contrast. As expected, numerical simulations show that the lateral field strength that is present at a step edge is the

K. Siegrist; E. D. Williams; V. W. Ballarotto

2003-01-01

245

The relationship between topography and gravity on Earth and Venus  

Microsoft Academic Search

The measurement of the admittance between the topography and the gravity of a planet as a function of wavelength provides important constraints on its interior processes. A detailed discussion of the influence of noise on such measurements shows that at long wavelengths the admittance is best determined in the frequency domain, using gravity as input and topography as output. This

Dan McKenzie

1994-01-01

246

The Topographic Mapping Flash Lidar for micro-topography of river systems  

NASA Astrophysics Data System (ADS)

The Topographic Mapping Flash Lidar (TMFL) instrument built by Ball Aerospace is a pushbroom lidar operating at 1064nm that provides the ability to map the topographic structure of river beds and surrounding terrain. The receiver is a pixilated array, allowing small-scale resolution of micro-topography that is critical to understanding river dynamics and the biodiversity of the area. The instrument uses no mechanical scanning, which is a key feature allowing the design to be applicable to space flight like the NASA Decadal Survey mission LIST. The TMFL instrument has been flown on a Twin Otter aircraft. This poster will exhibit examples of river topography over dry and wet riverbeds. Examples are given of imaging a river even when partially obscured under trees in an area of high canopy density.

Donley, B.; Ramond, T.; Weimer, C. S.; Ruppert, L.; Delker, T.; Applegate, J.

2010-12-01

247

Absolute Zero: Community Education Outreach Guide  

NSDL National Science Digital Library

This guide provides curricular resources for study of the history and science of the quest for ever colder temperature. Designed for teachers and informal educators of middle school students. this guide offers hands-on demonstrations, questions to encourage student participation, suggestions for class activities, and ways to encourage students to continue studying the science. Topics include low-temperature physics and the impact of technologies such as air conditioning, refrigeration and liquefied gases. This material is related to a two-part public broadcasting special, Absolute Zero, produced by Meridian Productions and Windfall Films. Absolute Zero is underwritten by the National Science Foundation and the Alfred P. Sloan Foundation and is based largely on Tom Shachtmanâs acclaimed book, Absolute Zero and the Conquest of Cold.

2008-09-18

248

Absolute Photoacoustic Thermometry in Deep Tissue  

PubMed Central

Photoacoustic (PA) thermography is a promising tool for temperature measurement in deep tissue. Here, we propose an absolute temperature measurement method based on the dual temperature dependences of the Grüneisen parameter and the speed of sound in tissue. By taking ratiometric measurements at two adjacent temperatures, we can eliminate the factors that are temperature irrelevant but difficult to correct for in deep tissue. To validate our method, absolute temperatures of blood-filled tubes embedded ~9 mm deep in chicken tissue were measured in a biologically relevant range from 28 °C to 46 °C. The temperature measurement accuracy was ~0.6 °C. The results suggest that our method can be potentially used for absolute temperature monitoring in deep tissue during thermotherapy. PMID:24322224

Tai, Stephen; Zhou, Yong; Wang, Lihong V.

2013-01-01

249

Absolute photoacoustic thermometry in deep tissue.  

PubMed

Photoacoustic thermography is a promising tool for temperature measurement in deep tissue. Here we propose an absolute temperature measurement method based on the dual temperature dependences of the Grüneisen parameter and the speed of sound in tissue. By taking ratiometric measurements at two adjacent temperatures, we can eliminate the factors that are temperature irrelevant but difficult to correct for in deep tissue. To validate our method, absolute temperatures of blood-filled tubes embedded ~9 mm deep in chicken tissue were measured in a biologically relevant range from 28°C to 46°C. The temperature measurement accuracy was ~0.6°C. The results suggest that our method can be potentially used for absolute temperature monitoring in deep tissue during thermotherapy. PMID:24322224

Yao, Junjie; Ke, Haixin; Tai, Stephen; Zhou, Yong; Wang, Lihong V

2013-12-15

250

Absolute distance metrology for space interferometers  

NASA Astrophysics Data System (ADS)

Space interferometers consisting of several free flying telescopes, such as the planned Darwin mission, require a complex metrology system to make all the components operate as a single instrument. Our research focuses on one of its sub-systems that measures the absolute distance between two satellites with high accuracy. For Darwin the required accuracy would be in the order of 10 µm over 250 meter. To measure this absolute distance, we are currently exploring the frequency sweeping interferometry technique. Its measurement principle is to first measure a phase in the interferometer, sweep a tunable laser over a known frequency interval and finally measure a second phase. By also counting the number of fringes during the sweep it is possible to determine the absolute path length difference without ambiguities. The wavelength at the endpoints of the sweep is stabilized on a Fabry-Perot cavity. In this way the unknown distance is directly referenced to the length of the Fabry-Perot cavity.

Swinkels, Bas L.; Wendrich, Thijs J.; Bhattacharya, Nandini; Wielders, Arno A.; Braat, Joseph J.

2004-09-01

251

Influence of planetary-scale topography on the diurnal thermal tide during the 1971 Martian dust storm  

NASA Technical Reports Server (NTRS)

Data obtained with the Mariner 9 infrared spectroscopy experiment during the Martian Dust Storm of 1971 to 1972 are examined for evidence of topographic influence on the atmospheric thermal structure. Temperature perturbations which are well correlated with the planetary scale topography are found superposed on the large amplitude diurnal thermal tide. Applications of tidal theory to the data indicate that the observed perturbations result from the kinematic interaction of the westward traveling diurnal wave with the large scale components of topography. The dominant mode is excited by the wave-number two topography component and is a vertically evanescent eastward traveling wave with an equivalent depth comparable to the atmospheric scale height. The principle dynamic effect of this mode is the enhancement of the amplitude of the near-surface diurnal wind to over 40m/sec in limited areas near 30 deg south latitude. It appears likely that dust was injected into the atmosphere in these regions during the storm.

Conrath, B. J.

1976-01-01

252

Precise Measurement of the Absolute Fluorescence Yield  

SciTech Connect

We present preliminary results of the absolute yield of fluorescence emission in atmospheric gases. Measurements were performed at the Fermilab Test Beam Facility with a variety of beam particles and gases. Absolute calibration of the fluorescence yield to 5% level was achieved by comparison with two known light sources - the Cherenkov light emitted by the beam particles, and a calibrated nitrogen laser. The uncertainty of the energy scale of current Ultra-High Energy Cosmic Rays experiments will be significantly improved by the AIRFLY measurement.

Ave, M.; Daumiller, K.; Keilhauer, B.; Klages, H.; Salamida, F.; Smida, R. [Karlsruhe Institute of Technology, IK, Postfach 6980, D - 76021 Karlsruhe (Germany); Bohacova, M.; Nozka, L.; Palatka, M.; Ridky, J.; Schovanek, P. [Institute of Physics of the Academy of Sciences of the Czech Republic, Na Slovance 2, CZ-182 21 Praha 8 (Czech Republic); Di Carlo, P.; Iarlori, M.; Petrera, S.; Rizi, V. [Dipartimento di Fisica dell'Universita de l'Aquila and INFN, Via Vetoio, I-67010 Coppito, Aquila (Italy); Di Giulio, C.; Verzi, V. [Dipartimento di Fisica dell'Universita di Roma Tor Vergata and Sezione INFN, Via della Ricerca Scientifica, I-00133 Roma (Italy); San Luis, P. Facal; Monasor, M.; Privitera, P. [University of Chicago, Enrico Fermi Institute and Kavli Institute for Cosmological Physics, 5640 S. Ellis Ave., Chicago, IL 60637 (United States)

2011-09-22

253

Absolute measurement of hyperspectral and angular reflection.  

PubMed

A new instrument for absolute measurement of hyperspectral and angular reflection is presented. The instrument determines absolute values of angular reflection quantities in a wavelength range from 380 to 780 nm with a 3 nm spectral resolution by using a white source and a CCD-based spectroradiometer. Through uncertainty evaluation, the measurement uncertainty is determined as 1.4%-2.9% (k=2) for white diffuse material of Spectralon. The gonioreflectometric determination and an integrating-sphere-based reflection measurement traceable to KRISS spectral reflectance scale are compared by determining hemispherical reflectance, which results in agreement in their uncertainties. PMID:25322100

Hwang, Jisoo

2014-09-20

254

Mask topography effect in chromeless phase lithography  

NASA Astrophysics Data System (ADS)

Different types of phase-shift masks (PSM) in combination with the proper illumination condition are widely used to allow 193nm lithography to print ever-decreasing pitches with a sufficient process window. A viable option for the 65nm node is Chromeless Phase Lithography (CPL), which combines a chromeless phase shift mask and 193nm off-axis illumination. It has been demonstrated that CPL has a high flexibility for through pitch imaging. Also concerning mask making CPL masks showed advantages over alternating and attenuated PSM [1]. This paper discusses how the mask quality and its topography influence the imaging performance of CPL. It is shown that mask topography is an important factor for CPL, as the imaging relies also on the quartz depth differences in the mask. The wafer image is sensitive to phase variations induced by the quartz etch depth and the sidewall profile. Their impact is separately studied using rigorous 3D mask electro-magnetic field simulations (Sigma-C Solid-CM). Correlation of experimental results to simulation explains that the observed pitch-dependent tilt in the Bossung curves is mainly related to the 3D character of the mask. In search for a global compensation valid through pitch, the simulation study also evaluates the effect of other contributors such as lens aberrations in the optical system, assist features and half-toning Cr zebra lines in the design. However, as the tilt is inherent to the CPL mask fabrication, a compensation of the Bossung tilt effect can only be obtained for specific combinations of all sources, as will be shown. We concentrate on the imaging of 70nm lines and 100nm contact holes in pitches ranging from dense up to isolated. The wafers are exposed on an ASML PAS5500/1100 ArF scanner working with a 0.75NA projection lens and various types of off-axis illumination. The wafers are evaluated on a top-down CD SEM (KLA-Tencor 8250XR).

Philipsen, Vicky; Bekaert, Joost; Vandenberghe, Geert; Jonckheere, Rik; Van Den Broeke, Douglas; Socha, Robert

2004-12-01

255

Topography and Volcanoes on Io (color)  

NASA Technical Reports Server (NTRS)

The images used to create this enhanced color composite of Io were acquired by NASA's Galileo spacecraft during its seventh orbit (G7) of Jupiter. Low sun angles near the terminator (day-night boundary near the left side of the image) offer lighting conditions which emphasize the topography or relief on the volcanic satellite. The topography appears very flat near the active volcanic centers such as Loki Patera (the large dark horse-shoe shaped feature near the terminator) while a variety of mountains and plateaus exist elsewhere. The big reddish-orange ring in the lower right is formed by material deposited from the eruption of Pele, Io's largest volcanic plume.

North is to the top of this picture which merges images obtained with the clear, red, green, and violet filters of the solid state imaging (CCD) system on NASA's Galileo spacecraft. The resolution is 6.1 kilometers per picture element. The images were taken on April 4th, 1997 at a range of 600,000 kilometers.

The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is an operating division of California Institute of Technology (Caltech).

Concurrent results from Galileo's exploration of Io appear in the October 15th, 1997 issue of Geophysical Research Letters. The papers are: Temperature and Area Constraints of the South Volund Volcano on Io from the NIMS and SSI Instruments during the Galileo G1 Orbit, by A.G. Davies, A.S. McEwen, R. Lopes-Gautier, L. Keszthelyi, R.W. Carlson and W.D. Smythe. High-temperature hot spots on Io as seen by the Galileo Solid-State Imaging (SSI) experiment, by A. McEwen, D. Simonelli, D. Senske, K. Klassen, L. Keszthelyi, T. Johnson, P. Geissler, M. Carr, and M. Belton. Io: Galileo evidence for major variations in regolith properties, by D. Simonelli, J. Veverka, and A. McEwen.

This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

1997-01-01

256

Accurate measurements of residual topography from the oceanic realm  

NASA Astrophysics Data System (ADS)

In the oceans, our understanding of plate subsidence as a function of age permits residual depth anomalies to be identified and mapped. These anomalies may reflect dynamic topography and could be an important means for constraining convective circulation of the sublithospheric mantle. Here we analyze a global database of seismic reflection and wide-angle profiles from heavily sedimented oceanic crust, which abuts continental lithosphere. At 449 locations, we calculated water-loaded subsidence, compared it with a reference age-depth relationship, and determined residual depth. We then combined these spot measurements of residual depth with observations from mid-oceanic ridges and from selected ship track bathymetry to construct a global map of residual depth. Our results suggest that the amplitude of residual depth varies by up to ±1 km with wavelengths of order 103 km. We compare our residual depths with free-air gravity and seismic tomographic anomalies. Our results show that residual depths correlate with long-wavelength gravity anomalies. In contrast, correlations between residual depths and vertically averaged shear velocity anomalies within the upper and/or the lower mantle are weaker. The largest discrepancies occur at short (˜1000 km) wavelengths. These combined observations suggest that residual depth anomalies could be generate by density variations within a thin (˜102 km) low-viscosity layer beneath the lithosphere. Our global compilation should play a significant role in helping to refine predictive geodynamical models.

Winterbourne, Jeffrey; White, Nicky; Crosby, Alistair

2014-06-01

257

Surface topography effects in protein adsorption on nanostructured carbon allotropes.  

PubMed

We report a molecular dynamics (MD) simulation study of protein adsorption on the surface of nanosized carbon allotropes, namely single-walled carbon nanotubes (SWNT) considering both the convex outer surface and the concave inner surface, together with a graphene sheet for comparison. These systems are chosen to investigate the effect of the surface curvature on protein adsorption at the same surface chemistry, given by sp(2) carbon atoms in all cases. The simulations show that proteins do favorably interact with these hydrophobic surfaces, as previously found on graphite which has the same chemical nature. However, the main finding of the present study is that the adsorption strength does depend on the surface topography: in particular, it is slightly weaker on the outer convex surfaces of SWNT and is conversely enhanced on the inner concave SWNT surface, being therefore intermediate for flat graphene. We additionally find that oligopeptides may enter the cavity of common SWNT, provided their size is small enough and the tube diameter is large enough for both entropic and energetic reasons. Therefore, we suggest that proteins can effectively be used to solubilize in water single-walled (and by analogy also multiwalled) carbon nanotubes through adsorption on the outer surface, as indeed experimentally found, and to functionalize them after insertion of oligopeptides within the cavity of nanotubes of appropriate size. PMID:23517008

Raffaini, Giuseppina; Ganazzoli, Fabio

2013-04-16

258

Topography of lactose permease from Escherichia coli.  

PubMed

The topography of lactose permease, in native membrane vesicles and after reconstitution of the purified protein into proteoliposomes, has been investigated by labeling the membrane-embedded portions of the protein using photoactivatable, hydrophobic reagents and by labeling the exposed portions of the protein with water-soluble, electrophilic reagents. Some sites of modification have been localized in fragments of the protein produced by chemical and enzymatic cleavage. These define a number of hydrophilic loops and membrane-spanning regions and give some substance to topographic models of the permease. The N-terminal third of the molecule was labeled by three photoactivatable reagents (3-(trifluoromethyl)-3-m-iodophenyldiazirine and the phospholipid analogues 2-(aceto-(4-benzoylphenylether]-1-palmitoylphosphatidylcholine) and 2-(4-azido-2-nitrophenylaminoacetyl)-1-palmitoylphosphatidylcholin e) as well as the water soluble, electrophilic reagents. The C-terminal part of the molecule is labeled by the diazirine and, to a lesser extent, by the phospholipid analogues. It apparently has more nucleophilic groups accessible to water-soluble reagents than the N-terminal domain, in which the density of apparently unreactive ionizable residues proved to be unexpectedly high. The apparent lack of reactivity of some of these residues may be explained either by their being buried in the protein moiety within the membrane domain, or by their close association with other ionizable residues on the surface of the protein. PMID:3053685

Page, M G; Rosenbusch, J P

1988-11-01

259

Absolute versus temporal anomaly and percent of saturation soil moisture spatial variability for six networks worldwide  

NASA Astrophysics Data System (ADS)

analysis of the spatial-temporal variability of soil moisture can be carried out considering the absolute (original) soil moisture values or relative values, such as the percent of saturation or temporal anomalies. Over large areas, soil moisture data measured at different sites can be characterized by large differences in their minimum, mean, and maximum absolute values, even though in relative terms their temporal patterns are very similar. In these cases, the analysis considering absolute compared with percent of saturation or temporal anomaly soil moisture values can provide very different results with significant consequences for their use in hydrological applications and climate science. In this study, in situ observations from six soil moisture networks in Italy, Spain, France, Switzerland, Australia, and United States are collected and analyzed to investigate the spatial soil moisture variability over large areas (250-150,000 km2). Specifically, the statistical and temporal stability analyses of soil moisture have been carried out for absolute, temporal anomaly, and percent of saturation values (using two different formulations for temporal anomalies). The results highlight that the spatial variability of the soil moisture dynamic (i.e., temporal anomalies) is significantly lower than that of the absolute soil moisture values. The spatial variance of the time-invariant component (temporal mean of each site) is the predominant contribution to the total spatial variance of absolute soil moisture data. Moreover, half of the networks show a minimum in the spatial variability for intermediate conditions when the temporal anomalies are considered, in contrast with the widely recognized behavior of absolute soil moisture data. The analyses with percent saturation data show qualitatively similar results as those for the temporal anomalies because of the applied normalization which reduces spatial variability induced by differences in mean absolute soil moisture only. Overall, we find that the analysis of the spatial-temporal variability of absolute soil moisture does not apply to temporal anomalies or percent of saturation values.

Brocca, L.; Zucco, G.; Mittelbach, H.; Moramarco, T.; Seneviratne, S. I.

2014-07-01

260

PROJECTIVE GROUP STRUCTURES AS ABSOLUTE GALOIS STRUCTURES  

E-print Network

PROJECTIVE GROUP STRUCTURES AS ABSOLUTE GALOIS STRUCTURES WITH BLOCK APPROXIMATION # by Dan Haran Bonn, Germany e­mail: pop@math.uni­bonn.de Abstract. A proper profinite group structure G is projective of a cover to a cartesian square . . . . . . . . . . . . . . . 19 4. Projective group structures

Pop, Florian

261

Absolute Points for Multiple Assignment Problems  

ERIC Educational Resources Information Center

An algorithm is presented to solve multiple assignment problems in which a cost is incurred only when an assignment is made at a given cell. The proposed method recursively searches for single/group absolute points to identify cells that must be loaded in any optimal solution. Unlike other methods, the first solution is the optimal solution. The…

Adlakha, V.; Kowalski, K.

2006-01-01

262

HARDCOVER JACKET COPY--FLAPS Absolutely Small  

E-print Network

salt dissolve in water, while oil does not, and much more "There are a few books that I always keep Michael D. Fayer, Ph.D. Our intuition about how things should behave is usually right in the everyday, Absolutely Small develops your intuition for the nature of things at their smallest and most intriguing level

Fayer, Michael D.

263

High-accuracy absolute distance metrology Proefschrift  

E-print Network

High-accuracy absolute distance metrology Proefschrift ter verkrijging van de graad van doctor aan-ray telescopes and synthetic aperture telescopes. For most of these, a metrology system that measures with a complex metrology system that monitors all the distances, angles and velocities in the system

264

Absolute Irreducibility of Polynomials via Newton Polytopes  

Microsoft Academic Search

A multivariable polynomial is associated with a polytope, called its Newton polytope. A polynomial is absolutely irreducible if its Newton polytope is indecomposable in the sense of Minkowski sum of polytopes. Two general constructions of indecomposable polytopes are given, and they give many simple irreducibility criteria including the well-known Eisenstein criterion. Polynomials from these criteria are over any field and

Shuhong Gao

2001-01-01

265

The Global Multi-Resolution Topography (GMRT) Synthesis  

NASA Astrophysics Data System (ADS)

Topographic maps provide a backdrop for research in nearly every earth science discipline. There is particular demand for bathymetry data in the ocean basins, where existing coverage is sparse. Ships and submersibles worldwide are rapidly acquiring large volumes of new data with modern swath mapping systems. The science community is best served by a global topography compilation that is easily accessible, up-to-date, and delivers data in the highest possible (i.e. native) resolution. To meet this need, the NSF-supported Marine Geoscience Data System (MGDS; www.marine-geo.org) has partnered with the National Geophysical Data Center (NGDC; www.ngdc.noaa.gov) to produce the Global Multi-Resolution Topography (GMRT) synthesis - a continuously updated digital elevation model that is accessible through Open Geospatial Consortium (OGC; www.opengeospatial.org) Web services. GMRT had its genesis in 1992 with the NSF RIDGE Multibeam Synthesis (RMBS); later grew to include the Antarctic Multibeam Synthesis (AMBS); expanded again to include the NSF Ridge 2000 and MARGINS programs; and finally emerged as a global compilation in 2005 with the NSF Legacy of Ocean Exploration (LOE) project. The LOE project forged a permanent partnership between MGDS and NGDC, in which swath bathymetry data sets are routinely published and exchanged via the Open Archives Initiative Protocol for Metadata Harvesting (OAI-PMH; www.openarchives.org). GMRT includes both color-shaded relief images and underlying elevation values at ten different resolutions as high as 100m. New data are edited, gridded, and tiled using tools originally developed by William Haxby at Lamont-Doherty Earth Observatory. Global and regional data sources include the NASA Shuttle Radar Topography Mission (SRTM; http://www.jpl.nasa.gov/srtm/); Smith & Sandwell Satellite Predicted Bathymetry (http://topex.ucsd.edu/marine_topo/); SCAR Subglacial Topographic Model of the Antarctic (BEDMAP; http://www.antarctica.ac.uk/bedmap/); and International Bathymetric Chart of the Arctic Ocean (IBCAO; http://www.ngdc.noaa.gov/mgg/bathymetry/arctic/). Local data sources include high-resolution bathymetry swaths and grids from over 210 research cruises, submersible dives, and related compilations to date. GMRT is accessible via a OGC Web Map Service (WMS) which offers dynamic resolution and on-the-fly map re- projection. A growing number of commercial and open-source clients support OGC protocols, including recent versions of Google Earth and Google Maps which now support WMS natively. GMRT is incorporated as a primary basemap in science Web portals and geobrowsers including EarthChem (www.earthchem.org) and GeoMapApp (www.geomapapp.org), which also serves the underlying elevation values. Future development work will include extension of GMRT to higher resolutions; addition of the International Bathymetric Chart of the Southern Ocean (IBCSO; www.ibcso.org) and the improved SRTM V2; and deployment of new OGC services including a Web Coverage Service (WCS) and Web Terrain Service (WTS).

Arko, R.; Ryan, W.; Carbotte, S.; Melkonian, A.; Coplan, J.; O'Hara, S.; Chayes, D.; Weissel, R.; Goodwillie, A.; Ferrini, V.; Stroker, K.; Virden, W.

2007-12-01

266

Shape, topography, gravity anomalies and tidal deformation of Titan  

NASA Astrophysics Data System (ADS)

Gravity measurements and elevation data from the Cassini mission have been used to create shape, global topography and gravity anomaly models of Titan that enable an improved understanding of its outer ice I shell structure. We provide constraints on the averaged ice shell thickness and its long-wavelength lateral variations, as well as the density of the subsurface ocean using gravity anomalies, the tidal Love number k2 measurement and long-wavelength topography. We found that Titan’s surface topography is consistent with an approximate isostatically compensated ice shell of variable thickness, likely in a thermally conductive or in a subcritical convective state, overlying a relatively dense subsurface ocean.

Mitri, Giuseppe; Meriggiola, Rachele; Hayes, Alex; Lefevre, Axel; Tobie, Gabriel; Genova, Antonio; Lunine, Jonathan I.; Zebker, Howard

2014-07-01

267

Pyroclastic density currents and local topography as seen with the conveyer model  

NASA Astrophysics Data System (ADS)

Pyroclastic density currents (PDCs) are multiphase flows generated during explosive volcanic eruptions, and they move down the volcano, and over the surrounding topography. The flow-topography interaction can play a fundamental role in the sedimentary processes, and in the resulting deposit facies architecture, as well as can play a dramatic role in the flow behavior, and in the associated volcanic hazard. This paper aims at discussing the PDC-topography interaction theme from the viewpoint of both deposits and flow structure, by accounting for appropriate literature, and revising the concepts in light of the theoretical conveyer model of Doronzo and Dellino (2013) on sedimentation and deposition in particulate density currents. First the effects, then the causes of the flow-topography interaction are discussed, in order to follow the historical development of theme concepts. The discussion is relative in terms of inertial and forced currents, which are defined on the basis of a dimensionless quantity (SD) representing the conservation of mass. Momentum equation relating depositional unit thickness, flow shear velocity, and density contrast shows that the flow is the cause of PDC motion, whereas the density contrast sustains the momentum, and the deposits are the process effect. In particular, the flow structure is described into three parts, flow-substrate boundary zone, boundary layer (lower part), and wake region (upper part) of the current. The facies architecture of PDC deposits, and the volcanic hazard depend on fluid dynamic and hydraulic behavior represented, in light of the conveyer model, by the balance of sedimentation and deposition rates through transport and erosion (“sedimentation-deposition” ratio, SD). This balance acts between flow-substrate boundary zone and boundary layer. The paper discussion mainly applies to small-to-intermediate volume eruptions. Field and modeling examples of Vulcano tuff cone and Colli Albani maar (Italy) constrain the conveyer model, whereas the literature of very large, ignimbrite-forming eruptions, and stratovolcanism is accounted for theme completeness. The main findings are some relative guidelines on PDC-topography interaction that can be used when modeling the flow, and interpreting the pyroclastic deposits: low SD is typical of inertial currents, whereas high SD is typical of forced currents, which can vary depending on topography.

Doronzo, Domenico M.; Dellino, Pierfrancesco

2014-05-01

268

Science in Motion: Isolated Araneiform Topography  

NASA Technical Reports Server (NTRS)

[figure removed for brevity, see original site] Figure 1

Have you ever found that to describe something you had to go to the dictionary and search for just the right word?

The south polar terrain is so full of unearthly features that we had to visit Mr. Webster to find a suitable term. 'Araneiform' means 'spider-like'. These are channels that are carved in the surface by carbon dioxide gas. We do not have this process on Earth.

The channels are somewhat radially organized (figure 1) and widen and deepen as they converge. In the past we've just refered to them as 'spiders.' 'Isolated araneiform topography' means that our features look like spiders that are not in contact with each other.

Observation Geometry Image PSP_003087_0930 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on 24-Mar-2007. The complete image is centered at -87.1 degrees latitude, 126.3 degrees East longitude. The range to the target site was 244.4 km (152.8 miles). At this distance the image scale is 24.5 cm/pixel (with 1 x 1 binning) so objects 73 cm across are resolved. The image shown here has been map-projected to 25 cm/pixel . The image was taken at a local Mars time of 08:22 PM and the scene is illuminated from the west with a solar incidence angle of 81 degrees, thus the sun was about 9 degrees above the horizon. At a solar longitude of 206.4 degrees, the season on Mars is Northern Autumn.

2007-01-01

269

Traveltime computation and imaging from rugged topography in 3D TTI media  

NASA Astrophysics Data System (ADS)

Foothill areas with rugged topography are of great potential for oil and gas seismic exploration, but subsurface imaging in these areas is very challenging. Seismic acquisition with larger offset and wider azimuth is necessary for seismic imaging in complex areas. However, the scale anisotropy in this case must be taken into account. To generalize the pre-stack depth migration (PSDM) to 3D transversely isotropic media with vertical symmetry axes (VTI) and tilted symmetry axes (TTI) from rugged topography, a new dynamic programming approach for the first-arrival traveltime computation method is proposed. The first-arrival time on every uniform mesh point is calculated based on Fermat's principle with simple calculus techniques and a systematic mapping scheme. In order to calculate the minimum traveltime, a set of nonlinear equations is solved on each mesh point, where the group velocity is determined by the group angle. Based on the new first-arrival time calculation method, the corresponding PSDM and migration velocity analysis workflow for 3D anisotropic media from rugged surface is developed. Numerical tests demonstrate that the proposed traveltime calculation method is effective in both VTI and TTI media. The migration results for 3D field data show that it is necessary to choose a smooth datum to remove the high wavenumber move-out components for PSDM with rugged topography and take anisotropy into account to achieve better images.

Liu, Shaoyong; Wang, Huazhong; Yang, Qinyong; Fang, Wubao

2014-02-01

270

X-ray topography of a lysozyme crystal  

SciTech Connect

X-ray topography methods were employed to identify defects in lysozyme crystals. White-beam and monochromatic topographs of lysozyme crystals obtained at the National Synchrotron Light Source are presented.

Stojanoff,V.; Siddons, D.

1996-01-01

271

Superoleophobic Surfaces through Control of Sprayed-on Stochastic Topography  

E-print Network

The liquid repellency and surface topography characteristics of coatings comprising a sprayed-on mixture of fluoroalkyl-functional precipitated silica and a fluoropolymer binder were examined using contact and sliding angle ...

Campos, Raymond

272

Calculation of irrotational wind pattern with application to Cleveland topography  

NASA Technical Reports Server (NTRS)

Small perturbation theory is applied to compute the deflection of the wind blowing across land that has an irregular topography. As an illustration, the method is applied first to the flow around a single hill of Gaussian profile. Then calculations are made for the irregular topography on the east side of Cleveland where the elevation changes by several hundred feet. It was found that the topography produced small wind deflections that would not be of practical importance in air pollution dispersion studies. The calculations were for a neutrally stable atmosphere. Although they are not investigated here, other factors such as thermal stratification of the atmosphere, diurnal variations, and convection currents resulting from the proximity of Lake Erie and the city heat island effect are expected to be more significant than the influence of topography.

Siegel, R.

1972-01-01

273

Teleseismic traveltimes, topography and the lithospheric structure across central Mongolia  

E-print Network

Teleseismic traveltimes, topography and the lithospheric structure across central Mongolia Carole to constrain the deep lithospheric structure of this region. Time residuals appear positively correlated-fitting Moho and lithosphere-asthenosphere boundary (LAB) geometries which satisfyingly reproduce the observed

Paris-Sud XI, Université de

274

X-Ray Topography of Shock Loaded Copper Crystals.  

National Technical Information Service (NTIS)

Single crystals of high purity copper subjected to shock loading have been examined by X-ray diffraction topography. The topographs reveal a basic substructure consisting of narrow, close packed kinks normal to highly stressed slip directions and extendin...

P. W. Kingman

1973-01-01

275

Infragravity waves over topography: generation, dissipation, and reflection  

E-print Network

Ocean surface infragravity waves (periods from 20 to 200 s) observed along the southern California coast are shown to be sensitive to the bottom topography of the shelf region, where propagation is linear, and of the ...

Thomson, James M. (James McArthur)

2006-01-01

276

Absolute dose calculations for Monte Carlo simulations of radiotherapy beams  

NASA Astrophysics Data System (ADS)

Monte Carlo (MC) simulations have traditionally been used for single field relative comparisons with experimental data or commercial treatment planning systems (TPS). However, clinical treatment plans commonly involve more than one field. Since the contribution of each field must be accurately quantified, multiple field MC simulations are only possible by employing absolute dosimetry. Therefore, we have developed a rigorous calibration method that allows the incorporation of monitor units (MU) in MC simulations. This absolute dosimetry formalism can be easily implemented by any BEAMnrc/DOSXYZnrc user, and applies to any configuration of open and blocked fields, including intensity-modulated radiation therapy (IMRT) plans. Our approach involves the relationship between the dose scored in the monitor ionization chamber of a radiotherapy linear accelerator (linac), the number of initial particles incident on the target, and the field size. We found that for a 10 × 10 cm2 field of a 6 MV photon beam, 1 MU corresponds, in our model, to 8.129 × 1013 ± 1.0% electrons incident on the target and a total dose of 20.87 cGy ± 1.0% in the monitor chambers of the virtual linac. We present an extensive experimental verification of our MC results for open and intensity-modulated fields, including a dynamic 7-field IMRT plan simulated on the CT data sets of a cylindrical phantom and of a Rando anthropomorphic phantom, which were validated by measurements using ionization chambers and thermoluminescent dosimeters (TLD). Our simulation results are in excellent agreement with experiment, with percentage differences of less than 2%, in general, demonstrating the accuracy of our Monte Carlo absolute dose calculations.

Popescu, I. A.; Shaw, C. P.; Zavgorodni, S. F.; Beckham, W. A.

2005-07-01

277

Morphology and Absolute Magnitudes of the SDSS DR7 QSOs  

NASA Astrophysics Data System (ADS)

The ESA mission Gaia will furnish a complete census of the Milky Way, delivering astrometrics, dynamics, and astrophysics information for 1 billion stars. Operating in all-sky repeated survey mode, Gaia will also provide measurements of extra-galactic objects. Among the later there will be at least 500,000 QSOs that will be used to build the reference frame upon which the several independent observations will be combined and interpreted. Not all the QSOs are equally suited to fulfill this role of fundamental, fiducial grid-points. Brightness, morphology, and variability define the astrometric error budget for each object. We made use of 3 morphological parameters based on the PSF sharpness, circularity and gaussianity, which enable us to distinguish the "real point-like" QSOs. These parameters are being explored on the spectroscopically certified QSOs of the SDSS DR7, to compare the performance against other morphology classification schemes, as well as to derive properties of the host galaxy. We present a new method, based on the Gaia quasar database, to derive absolute magnitudes, on the SDSS filters domain. The method can be extrapolated all over the optical window, including the Gaia filters. We discuss colors derived from SDSS apparent magnitudes and colors based on absolute magnitudes that we obtained tanking into account corrections for dust extinction, either intergalactic or from the QSO host, and for the Lyman ? forest. In the future we want to further discuss properties of the host galaxies, comparing for e.g. the obtained morphological classification with the color, the apparent and absolute magnitudes, and the redshift distributions.

Coelho, B.; Andrei, A. H.; Antón, S.

2014-10-01

278

Phase contrast in Simultaneous Topography and Recognition imaging.  

PubMed

The operation of a force microscope in Simultaneous Topography and Recognition (TREC) imaging mode is analyzed by means of numerical simulations. Both topography and recognition signals are analyzed by using a worm-like chain force as the specific interaction between the functionalized tip probe and the sample. The special feedback mechanism in this mode is shown to couple the phase signal to the presence of molecular recognition interactions even in absence of dissipation. PMID:19523768

Fuss, M C; Sahagún, E; Köber, M; Briones, F; Luna, M; Sáenz, J J

2009-08-01

279

Defect analysis in crystals using X-ray topography  

Microsoft Academic Search

A brief review of X-ray topography—a nondestructive method for direct observation and characterization of defects in single crystals—is presented here. The origin and development of this characterization method and the different techniques derived from it are described. Emphasis is placed on synchrotron X-ray topography and its application in studying various crystal imperfec- tions. Mechanisms of contrast formation on X-ray topographs

Balaji Raghothamachar; Govindhan Dhanaraj; Jie Bai; Michael Dudley

2006-01-01

280

X ray topography study of gallium phosphate crystals and resonators  

Microsoft Academic Search

Using the synchrotron radiation delivered by the DCI storage ring at LURE (Orsay, France), the X-ray topography technique was used to study the crystalline perfection of GaPO4 samples grown under different conditions. The growth of gallium phosphate on a berlinite seed is analyzed by X-ray section topography. The results obtained demonstrate the feasibility of gallium phosphate epitaxy on large berlinite

B. Capelle; A. Zarka; J. Schwartzel; J. Detaint; Y. Zheng; A. Ibanez; E. Philippot

1993-01-01

281

X-ray topography study of microsegregation in crystals  

Microsoft Academic Search

Concentration microinhomogeneities in crystals were characterized using x-ray topography, digital image processing, and spectral\\u000a analysis of signals. Based on the features in lattice strains in such layered inhomogeneous crystals, methods for optimizing\\u000a the conditions of x-ray topography detection of growth striations were proposed to obtain quantitative information on the\\u000a composition fluctuation amplitude and spatial characteristics.

I. A. Prokhorov; I. Z. Bezbakh; B. G. Zakharov; I. L. Shul’pina

2007-01-01

282

Feedback Control Scheme for Scanning X-Ray Topography  

Microsoft Academic Search

Feedback control of scanning x-ray topography is described. A control scheme is developed that maintains the x-ray topography system at all times at the peak of the rocking curve I(?). The mathematical control scheme is implemented through an angular derivative generator capable of generating the signal dI?d? on a continuous basis. Circuit requirements to measure dI?d? continuously are established. Actual

L. J. van Mellaert; G. H. Schwuttke

1972-01-01

283

Absolutely continuous spectrum implies ballistic transport for quantum particles in a random potential on tree graphs  

SciTech Connect

We discuss the dynamical implications of the recent proof that for a quantum particle in a random potential on a regular tree graph absolutely continuous (ac) spectrum occurs non-perturbatively through rare fluctuation-enabled resonances. The main result is spelled in the title.

Aizenman, Michael [Departments of Physics and Mathematics, Princeton University, Princeton, New Jersey 08544 (United States); Warzel, Simone [Zentrum Mathematik, TU Munich, Boltzmannstr. 3, 85747 Garching (Germany)

2012-09-15

284

[Absolute measurement of laminar flow with the aid of an orthogonal excitation technic in NMR tomography].  

PubMed

A method for absolute measurement of flow quantities by excitation of a slice orthogonal to the measuring plane is presented. The developing flow profile can be imaged directly and its dynamic behaviour can be sampled and measured using the multiecho technique. Simple formulas can be derived by means of Hagen-Poiseuille's law for quantification. PMID:3024261

Bielke, G; Meindl, S; von Seelen, W

1986-11-01

285

Effect of topography on deposition from dilute pyroclastic density currents simulated by Ansys Fluent software  

NASA Astrophysics Data System (ADS)

Pyroclastic density currents are volcanic gas-particle flows that move along volcano flanks and over the neighboring topography. Flow particle concentration can vary between two end members, concentrated and dilute. When a pyroclastic density current interacts with an uneven topography, the flow-field variables (velocity, pressure, particle concentration) are drastically changed at the flow-substrate boundary. These changes may significantly affect the sedimentation rate and the resulting deposits can record such effects in their sedimentological features. Here we show, by means of numerical simulations, how a dilute pyroclastic density current interacts with four different types of topographies, namely: flat, one hill, one valley and two hills. The simulations are carried out by Ansys Fluent commercial software for applications in fluid dynamic engineering. Our numerical scheme treats the very fine particles as being in full thermo-mechanical equilibrium with the volcanic gas (pseudo-fluid phase), and the trajectories of the coarser particles are tracked by means of the pseudo-fluid solution (Lagrangian particles). There is a two-way coupling between the pseudo-fluid phase and Lagrangian particles, which accounts for the reciprocal mechanical effects of the two phases. Numerical results are then used to analyze the local effects of topography on the deposition of the Lagrangian particles, by monitoring with time and space the local changes at the boundary between the dilute pyroclastic density current and substrate. We use the sedimentation rate and grain-size distribution of the Lagrangian particles as proxies of the deposit features, and by these parameters we compare qualitatively the numerical results with the deposits of known eruptions: Mount St. Helens blast, Taupo ignimbrite and Vulcano surge deposits. The results reproduce qualitatively the natural deposits very well, and we conclude that Ansys Fluent software could be used in volcanology with success.

Doronzo, Domenico Maria; Valentine, Greg A.; Dellino, Pierfrancesco; de Tullio, Marco D.

2010-05-01

286

Absolute calibration of TFTR helium proportional countersa)  

NASA Astrophysics Data System (ADS)

The TFTR helium proportional counters are located in the central five (5) channels of the TFTR multichannel neutron collimator. These detectors were absolutely calibrated using a 14 MeV neutron generator positioned at the horizontal midplane of the TFTR vacuum vessel. The neutron generator position was scanned in centimeter steps to determine the collimator aperture width to 14 MeV neutrons and the absolute sensitivity of each channel. Neutron profiles were measured for TFTR plasmas with time resolution between 5 and 50 ms depending upon count rates. The He detectors were used to measure the burnup of 1 MeV tritons in deuterium plasmas, the transport of tritium in trace tritium experiments, and the residual tritium levels in plasmas following 50:50 DT experiments.

Strachan, J. D.; Barnes, Cris W.; Diesso, M.; Jassby, D.; Johnson, L.; Loughlin, M.; McCauley, S.; Munsat, T.; Roquemore, A. L.

1995-02-01

287

Absolute-magnitude Distributions of Supernovae  

NASA Astrophysics Data System (ADS)

The absolute-magnitude distributions of seven supernova (SN) types are presented. The data used here were primarily taken from the Asiago Supernova Catalogue, but were supplemented with additional data. We accounted for both foreground and host-galaxy extinction. A bootstrap method is used to correct the samples for Malmquist bias. Separately, we generate volume-limited samples, restricted to events within 100 Mpc. We find that the superluminous events (MB < -21) make up only about 0.1% of all SNe in the bias-corrected sample. The subluminous events (MB > -15) make up about 3%. The normal Ia distribution was the brightest with a mean absolute blue magnitude of -19.25. The IIP distribution was the dimmest at -16.75.

Richardson, Dean; Jenkins, Robert L., III; Wright, John; Maddox, Larry

2014-05-01

288

An absolute measure for a key currency  

NASA Astrophysics Data System (ADS)

It is generally considered that the US dollar and the euro are the key currencies in the world and in Europe, respectively. However, there is no absolute general measure for a key currency. Here, we investigate the 24-hour periodicity of foreign exchange markets using a recurrence plot, and define an absolute measure for a key currency based on the strength of the periodicity. Moreover, we analyze the time evolution of this measure. The results show that the credibility of the US dollar has not decreased significantly since the Lehman shock, when the Lehman Brothers bankrupted and influenced the economic markets, and has increased even relatively better than that of the euro and that of the Japanese yen.

Oya, Shunsuke; Aihara, Kazuyuki; Hirata, Yoshito

289

A Global Approach to Absolute Parallelism Geometry  

NASA Astrophysics Data System (ADS)

In this paper we provide a global investigation of the geometry of parallelizable manifolds (or absolute parallelism geometry) frequently used in applications. We discuss different linear connections and curvature tensors from a global point of view. We give an existence and uniqueness theorem for a remarkable linear connection, called the canonical connection. Different curvature tensors are expressed in a compact form in terms of the torsion tensor of the canonical connection only. Using the Bianchi identities, some interesting identities are derived. An important special fourth-order tensor, which we refer to as Wanas tensor, is globally defined and investigated. Finally a "double-view" for the fundamental geometric objects of an absolute parallelism space is established: The expressions of these geometric objects are computed in the parallelization basis and are compared with the corresponding local expressions in the natural basis. Physical aspects of some geometric objects considered are pointed out.

Youssef, Nabil L.; Elsayed, Waleed A.

2013-08-01

290

Absolute and relative dosimetry for ELIMED  

SciTech Connect

The definition of detectors, methods and procedures for the absolute and relative dosimetry of laser-driven proton beams is a crucial step toward the clinical use of this new kind of beams. Hence, one of the ELIMED task, will be the definition of procedures aiming to obtain an absolute dose measure at the end of the transport beamline with an accuracy as close as possible to the one required for clinical applications (i.e. of the order of 5% or less). Relative dosimetry procedures must be established, as well: they are necessary in order to determine and verify the beam dose distributions and to monitor the beam fluence and the energetic spectra during irradiations. Radiochromic films, CR39, Faraday Cup, Secondary Emission Monitor (SEM) and transmission ionization chamber will be considered, designed and studied in order to perform a fully dosimetric characterization of the ELIMED proton beam.

Cirrone, G. A. P.; Schillaci, F.; Scuderi, V. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Institute of Physics Czech Academy of Science, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic)] [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Institute of Physics Czech Academy of Science, ELI-Beamlines project, Na Slovance 2, Prague (Czech Republic); Cuttone, G.; Candiano, G.; Musumarra, A.; Pisciotta, P.; Romano, F. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy)] [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania (Italy); Carpinelli, M. [INFN Sezione di Cagliari, c/o Dipartimento di Fisica, Università di Cagliari, Cagliari (Italy)] [INFN Sezione di Cagliari, c/o Dipartimento di Fisica, Università di Cagliari, Cagliari (Italy); Leonora, E.; Randazzo, N. [INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy)] [INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy); Presti, D. Lo [INFN-Sezione di Catania, Via Santa Sofia 64, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy)] [INFN-Sezione di Catania, Via Santa Sofia 64, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Raffaele, L. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy)] [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and INFN-Sezione di Catania, Via Santa Sofia 64, Catania (Italy); Tramontana, A. [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy)] [INFN, Laboratori Nazionali del Sud, Via Santa Sofia 62, Catania, Italy and Università di Catania, Dipartimento di Fisica e Astronomia, Via S. Sofia 64, Catania (Italy); Cirio, R.; Sacchi, R.; Monaco, V. [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino, Italy and Università di Torino, Dipartimento di Fisica, Via P.Giuria, 1 10125 Torino (Italy)] [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino, Italy and Università di Torino, Dipartimento di Fisica, Via P.Giuria, 1 10125 Torino (Italy); Marchetto, F.; Giordanengo, S. [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino (Italy)] [INFN, Sezione di Torino, Via P.Giuria, 1 10125 Torino (Italy)

2013-07-26

291

Absolute distance metrology for space interferometers  

NASA Astrophysics Data System (ADS)

Future space missions, among which the Darwin Space Interferometer, will consist of several free flying satellites. A complex metrology system is required to have all the components fly accurately in formation and have it operate as a single instrument. Our work focuses on a possible implementation of the sub-system that measures the absolute distance between two satellites with high accuracy. For Darwin the required accuracy is on the order of 70 micrometer over a distance of 250 meter. We are exploring a technique called frequency sweeping interferometry, which involves interferometrically measuring a phase difference while sweeping the wavelength of a tunable laser. This phase difference is directly proportional to the absolute distance. A very high finesse Fabry-Perot cavity is used as a reference standard, to which the laser is locked at the end-points of the sweep. We will discuss our measurement scheme, our set-up and some first measurements.

Swinkels, Bas L.; Latoui, Abdelhalim; Bhattacharya, Nandini; Wielders, Arno A.; Braat, Joseph J. M.

2005-08-01

292

Absolute distance metrology for space interferometers  

NASA Astrophysics Data System (ADS)

Future space missions, among which the Darwin Space Interferometer, will consist of several free flying satellites. A complex metrology system is required to have all the components fly accurately in formation and have it operate as a single instrument. Our work focuses on a possible implementation of the sub-system that measures the absolute distance between two satellites with high accuracy. For Darwin the required accuracy is on the order of 70 micrometer over a distance of 250 meter. We are exploring a technique called frequency sweeping interferometry, which involves interferometrically measuring a phase difference while sweeping the wavelength of a tunable laser. This phase difference is directly proportional to the absolute distance. A very high finesse Fabry-Perot cavity is used as a reference standard, to which the laser is locked end-points of the sweep. We will discuss the control system that drives the setup and show some first experimental results.

Swinkels, Bas L.; Bhattacharya, Nandini; Wielders, Arno A.; Braat, Joseph J. M.

2005-06-01

293

Absolute photoionization cross sections of atomic oxygen  

NASA Technical Reports Server (NTRS)

The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

Samson, J. A. R.; Pareek, P. N.

1985-01-01

294

Absolute photoionization cross sections of atomic oxygen  

NASA Technical Reports Server (NTRS)

The absolute values of photoionization cross sections of atomic oxygen were measured from the ionization threshold to 120 A. An auto-ionizing resonance belonging to the 2S2P4(4P)3P(3Do, 3So) transition was observed at 479.43 A and another line at 389.97 A. The experimental data is in excellent agreement with rigorous close-coupling calculations that include electron correlations in both the initial and final states.

Samson, J. A. R.; Pareek, P. N.

1982-01-01

295

On absolute CM-periods, II  

Microsoft Academic Search

For a CM-fieldK, Shimura defined the period symbolpK by factorizing periods of abelian varieties with complex multiplication. We define the absolute period symbolgK using division values of the multiple gamma function and conjecture that pK coincides with gK up to the multiplication by algebraic numbers. Taking the action of Gal(Q Q) into account, we present a refined version of this

Hiroyuki Yoshida

1998-01-01

296

The absolute bioavailability of caffeine in man  

Microsoft Academic Search

The absolute bioavailability of orally administered caffeine was investigated in 10 healthy adult male volunteers, aged 18.8 to 30.0 years. The subjects were administered a 5 mg\\/kg dose of caffeine as either an aqueous oral solution or an intravenous infusion, on separate occasions about 1 week apart, in a randomized crossover fashion. Plasma samples were collected over the 24-h period

J. Blanchard; S. J. A. Sawers

1983-01-01

297

The absolute spectrophotometric catalog by Anita Cochran  

NASA Astrophysics Data System (ADS)

The absolute spectrophotometric catalog by Anita Cochran is presented in a machine-readable form. The catalog systematizes observations acquired at the McDonald Observatory in 1977-1978. The data are compared with other sources, in particular, the calculated broadband stellar magnitudes are compared with photometric observations by other authors, to show that the observational data given in the catalog are reliable and suitable for a variety of applications. Observations of variable stars of different types make Cochran's catalog especially valuable.

Burnashev, V. I.; Burnasheva, B. A.; Ruban, E. V.; Hagen-Torn, E. I.

2014-06-01

298

The absolute position of a resonance peak  

E-print Network

It is common practice in scattering theory to correlate between the position of a resonance peak in the cross section and the real part of a complex energy of a pole of the scattering amplitude. In this work we show that the resonance peak position appears at the absolute value of the pole's complex energy rather than its real part. We further demonstrate that a local theory of resonances can still be used even in cases previously thought impossible.

Shachar Klaiman; Nimrod Moiseyev

2010-05-26

299

Absolute distance metrology for space interferometers  

NASA Astrophysics Data System (ADS)

Space interferometers consisting of several free flying telescopes, such as the planned Darwin mission, require a complex metrology system to make all the components operate as a single instrument. This metrology system consists of various sub-systems to monitor distances, angles and speeds. Our research focuses on one of these sub-systems that measures the absolute distance between two satellites with high accuracy. For Darwin the required accuracy would be in the order of 10 ?m over 250 meter. To measure this absolute distance, we are currently building a frequency sweeping interferometer. It is operated by first measuring a phase in the interferometer, sweeping a tunable laser over a known frequency interval and finally measuring a second phase. By also counting the number of fringes during the sweep it is possible to determine the absolute path length difference without ambiguities. We plan on actively stabilizing the wavelength at the endpoints of the sweep on a Fabry-Perot cavity using the Pound-Drever-Hall technique. In this way the unknown distance is directly referenced to the length of the Fabry-Perot cavity.

Swinkels, B. L.; Wendrich, T. J.; Bhattacharya, N.; Wielders, A. A.; Braat, J. J. M.

2004-06-01

300

First order sensitivity analysis of flexible multibody systems using absolute nodal coordinate formulation  

Microsoft Academic Search

Design sensitivity analysis of flexible multibody systems is important in optimizing the performance of mechanical systems.\\u000a The choice of coordinates to describe the motion of multibody systems has a great influence on the efficiency and accuracy\\u000a of both the dynamic and sensitivity analysis. In the flexible multibody system dynamics, both the floating frame of reference\\u000a formulation (FFRF) and absolute nodal

Ting Pi; Yunqing Zhang; Liping Chen

301

Absolute and relative quantification of RNA modifications via biosynthetic isotopomers.  

PubMed

In the resurging field of RNA modifications, quantification is a bottleneck blocking many exciting avenues. With currently over 150 known nucleoside alterations, detection and quantification methods must encompass multiple modifications for a comprehensive profile. LC-MS/MS approaches offer a perspective for comprehensive parallel quantification of all the various modifications found in total RNA of a given organism. By feeding (13)C-glucose as sole carbon source, we have generated a stable isotope-labeled internal standard (SIL-IS) for bacterial RNA, which facilitates relative comparison of all modifications. While conventional SIL-IS approaches require the chemical synthesis of single modifications in weighable quantities, this SIL-IS consists of a nucleoside mixture covering all detectable RNA modifications of Escherichia coli, yet in small and initially unknown quantities. For absolute in addition to relative quantification, those quantities were determined by a combination of external calibration and sample spiking of the biosynthetic SIL-IS. For each nucleoside, we thus obtained a very robust relative response factor, which permits direct conversion of the MS signal to absolute amounts of substance. The application of the validated SIL-IS allowed highly precise quantification with standard deviations <2% during a 12-week period, and a linear dynamic range that was extended by two orders of magnitude. PMID:25129236

Kellner, Stefanie; Ochel, Antonia; Thüring, Kathrin; Spenkuch, Felix; Neumann, Jennifer; Sharma, Sunny; Entian, Karl-Dieter; Schneider, Dirk; Helm, Mark

2015-02-01

302

Topography and hillslope soil water relationships in a catchment of low relief  

NASA Astrophysics Data System (ADS)

Soil water potentials are mapped on a 6° hillslope during summer and winter conditions in a 0.8-km 2 catchment. It is shown that the dynamic hillslope contributing area is maintained at the slope base for long periods after precipitation has ceased. Additionally, the focus of the hillslope soil water convergence is not always at the hollow base, but is seen to migrate in the downstream direction and to accord with a hillslope spur. Microtopographic features are shown thereby to influence, but not to be the sole dominant control upon the spatial disposition of hillslope contributing areas in low-angled topography.

Anderson, M. G.; Kneale, P. E.

1980-05-01

303

The combined effect of topography and vegetation on the temporal evolution of catchment connectivity  

NASA Astrophysics Data System (ADS)

The deconvolution of whole catchment runoff response into its constituent small-scale runoff generation processes remains a grand challenge in catchment hydrology. The extent to which the intersection of topography and vegetation influences the hydrologic connectivity of catchment uplands to the riparian and stream system is largely unknown. Often studied topographic variables can be considered static over timescales of interest for most hydrologic questions. However, less attention has been paid to more dynamic catchment variables, particularly vegetation. Plants can act as spatial and temporal sinks for water through transpiration, adding a biological layer to otherwise topographically/hydrologically controlled runoff generation. The runoff observed at the catchment outlet therefore contains imprints from interactions between both static and dynamic catchment structure. Here we present a modeling framework that explicitly incorporates static (topography) and dynamic (vegetation) catchment structure. We employ sub-daily evapotranspiration data from an eddy flux tower co-located within a highly instrumented (>150 recording groundwater wells) and gaged catchment to parse the effect of current and synthetic vegetation pattern scenarios on the temporal evolution of hydrologic connectivity.

Nippgen, F.; McGlynn, B. L.; Emanuel, R. E.

2012-04-01

304

Shuttle Topography Data Inform Solar Power Analysis  

NASA Technical Reports Server (NTRS)

The next time you flip on a light switch, there s a chance that you could be benefitting from data originally acquired during the Space Shuttle Program. An effort spearheaded by Jet Propulsion Laboratory (JPL) and the National Geospatial-Intelligence Agency (NGA) in 2000 put together the first near-global elevation map of the Earth ever assembled, which has found use in everything from 3D terrain maps to models that inform solar power production. For the project, called the Shuttle Radar Topography Mission (SRTM), engineers at JPL designed a 60-meter mast that was fitted onto Shuttle Endeavour. Once deployed in space, an antenna attached to the end of the mast worked in combination with another antenna on the shuttle to simultaneously collect data from two perspectives. Just as having two eyes makes depth perception possible, the SRTM data sets could be combined to form an accurate picture of the Earth s surface elevations, the first hight-detail, near-global elevation map ever assembled. What made SRTM unique was not just its surface mapping capabilities but the completeness of the data it acquired. Over the course of 11 days, the shuttle orbited the Earth nearly 180 times, covering everything between the 60deg north and 54deg south latitudes, or roughly 80 percent of the world s total landmass. Of that targeted land area, 95 percent was mapped at least twice, and 24 percent was mapped at least four times. Following several years of processing, NASA released the data to the public in partnership with NGA. Robert Crippen, a member of the SRTM science team, says that the data have proven useful in a variety of fields. "Satellites have produced vast amounts of remote sensing data, which over the years have been mostly two-dimensional. But the Earth s surface is three-dimensional. Detailed topographic data give us the means to visualize and analyze remote sensing data in their natural three-dimensional structure, facilitating a greater understanding of the features and processes taking place on Earth."

2013-01-01

305

Predicting Maximum Lake Depth from Surrounding Topography  

EPA Science Inventory

Lake volume aids understanding of the physical and ecological dynamics of lakes, yet is often not readily available. The data needed to calculate lake volume (i.e. bathymetry) are usually only collected on a lake by lake basis and are difficult to obtain across broad regions. ...

306

Corneal Topography: A review, new ANSI standards and problems to solve Stanley A. Klein  

E-print Network

Corneal Topography: A review, new ANSI standards and problems to solve Stanley A. Klein School@spectacle.berkeley.edu Abstract: This review of corneal topography has three sections: 1. a brief introduction to how corneal for corneal topography. 3. an examination of problems still facing corneal topography. OCIS codes: (120

Klein, Stanley

307

The Absolute Calibration of the EUV Imaging Spectrometer on Hinode  

NASA Astrophysics Data System (ADS)

We investigate the absolute calibration of the EUV Imaging Spectrometer (EIS) on Hinode by comparing EIS full-disk mosaics with irradiance observations from the EUV Variability Experiment on the Solar Dynamics Observatory. We also use extended observations of the quiet corona above the limb combined with a simple differential emission measure model to establish new effective area curves that incorporate information from the most recent atomic physics calculations. We find that changes to the EIS instrument sensitivity are a complex function of both time and wavelength. We find that the sensitivity is decaying exponentially with time and that the decay constants vary with wavelength. The EIS short wavelength channel shows significantly longer decay times than the long wavelength channel.

Warren, Harry P.; Ugarte-Urra, Ignacio; Landi, Enrico

2014-07-01

308

Visualization of High-Resolution LiDAR Topography in Google Earth  

NASA Astrophysics Data System (ADS)

The growing availability of high-resolution LiDAR (Light Detection And Ranging) topographic data has proven to be revolutionary for Earth science research. These data allow scientists to study the processes acting on the Earth’s surfaces at resolutions not previously possible yet essential for their appropriate representation. In addition to their utility for research, the data have also been recognized as powerful tools for communicating earth science concepts for education and outreach purposes. Unfortunately, the massive volume of data produced by LiDAR mapping technology can be a barrier to their use. To facilitate access to these powerful data for research and educational purposes, we have been exploring the use of Keyhole Markup Language (KML) and Google Earth to deliver LiDAR-derived visualizations. The OpenTopography Portal (http://www.opentopography.org/) is a National Science Foundation-funded facility designed to provide access to Earth science-oriented LiDAR data. OpenTopography hosts a growing collection of LiDAR data for a variety of geologic domains, including many of the active faults in the western United States. We have found that the wide spectrum of LiDAR users have variable scientific applications, computing resources, and technical experience and thus require a data distribution system that provides various levels of access to the data. For users seeking a synoptic view of the data, and for education and outreach purposes, delivering full-resolution images derived from LiDAR topography into the Google Earth virtual globe is powerful. The virtual globe environment provides a freely available and easily navigated viewer and enables quick integration of the LiDAR visualizations with imagery, geographic layers, and other relevant data available in KML format. Through region-dependant network linked KML, OpenTopography currently delivers over 20 GB of LiDAR-derived imagery to users via simple, easily downloaded KMZ files hosted at the Portal. This method provides seamlessly access to hillshaded imagery for both bare earth and first return terrain models with various angles of illumination. Seamless access to LiDAR-derived imagery in Google Earth has proven to be the most popular product available in the OpenTopography Portal. The hillshade KMZ files have been downloaded over 3000 times by users ranging from earthquake scientists to K-12 educators who wish to introduce cutting edge real world data into their earth science lessons. OpenTopography also provides dynamically generated KMZ visualizations of LiDAR data products produced when users choose to use the OpenTopography point cloud access and processing system. These Google Earth compatible products allow users to quickly visualize the custom terrain products they have generated without the burden of loading the data into a GIS environment. For users who have installed the Google Earth browser plug-in, these visualizations can be launched directly from the OpenTopography results page and viewed directly in the browser.

Crosby, C. J.; Nandigam, V.; Arrowsmith, R.; Blair, J. L.

2009-12-01

309

Soil moisture variation in relation to topography and land use in a hillslope catchment of the Loess Plateau, China  

NASA Astrophysics Data System (ADS)

The profile characteristics and the temporal dynamics of soil moisture variation were studied at 26 locations in Da Nangou catchment (3.5 km 2) in the loess area of China. Soil moisture measurements were performed biweekly at five depths in the soil profile (0-5, 10-15, 20-25, 40-45 and 70-75 cm) from May to October 1998 using Delta-T theta probe. Soil moisture profile type and temporal variation type and their relationship to topography and land use were identified by detrended canonical correspondence analysis (DCCA) and correlation analysis. The profile distribution of time-averaged soil moisture content can be classified into three types i.e. decreasing-type, waving-type and increasing-type. The profile features of soil moisture (e.g. profile gradient and profile variability) are influenced by different environmental factors. The profile type of soil moisture is only attributed to land use while profile gradient and profile variability of soil moisture is mainly related to land use and topography (e.g. landform type and slope). The temporal dynamics of layer-averaged soil moisture content is grouped into three types including three-peak type, synchro-four-peak type and lagged-four-peak type. These types are controlled by topography rather than by land use. The temporal dynamic type of soil moisture shows significant correlation with relative elevation, slope, aspect, while temporal variance displays significant relation with slope shape. The mean soil moisture is related to both the profile and dynamics features of soil moisture and is controlled by both land use and topography (e.g. aspect, position, slope and relative elevation). The spatial variability of soil moisture across landscape varies with both soil depths and temporal evolution.

Qiu, Yang; Fu, Bojie; Wang, Jun; Chen, Liding

2001-01-01

310

Responses of microbial biomass and respiration of soil to topography, burning, and nitrogen fertilization in a temperate steppe  

Microsoft Academic Search

Temporal dynamics of microbial biomass and respiration of soil and their responses to topography, burning, N fertilization,\\u000a and their interactions were determined in a temperate steppe in northern China. Soil microbial indices showed strong temporal\\u000a variability over the growing season. Soil microbial biomass C (MBC) and N (MBN) were 14.8 and 11.5% greater in the lower than\\u000a upper slope, respectively.

Weixing Liu; Wenhua Xu; Yi Han; Changhui Wang; Shiqiang Wan

2007-01-01

311

Achieving Climate Change Absolute Accuracy in Orbit  

NASA Technical Reports Server (NTRS)

The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5-50 micron), the spectrum of solar radiation reflected by the Earth and its atmosphere (320-2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a "NIST [National Institute of Standards and Technology] in orbit." CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations.

Wielicki, Bruce A.; Young, D. F.; Mlynczak, M. G.; Thome, K. J; Leroy, S.; Corliss, J.; Anderson, J. G.; Ao, C. O.; Bantges, R.; Best, F.; Bowman, K.; Brindley, H.; Butler, J. J.; Collins, W.; Dykema, J. A.; Doelling, D. R.; Feldman, D. R.; Fox, N.; Huang, X.; Holz, R.; Huang, Y.; Jennings, D.; Jin, Z.; Johnson, D. G.; Jucks, K.; Kato, S.; Kratz, D. P.; Liu, X.; Lukashin, C.; Mannucci, A. J.; Phojanamongkolkij, N.; Roithmayr, C. M.; Sandford, S.; Taylor, P. C.; Xiong, X.

2013-01-01

312

Determination of the absolute contours of optical flats  

NASA Technical Reports Server (NTRS)

Emersons procedure is used to determine true absolute contours of optical flats. Absolute contours of standard flats are determined and a comparison is then made between standard and unknown flats. Contour differences are determined by deviation of Fizeau fringe.

Primak, W.

1969-01-01

313

Gravity, Topography, and Magnetic Field of Mercury from Messenger  

NASA Technical Reports Server (NTRS)

On 18 March 2011, the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft was inserted into a 12-hour, near-polar orbit around Mercury, with an initial periapsis altitude of 200 km, initial periapse latitude of 60 deg N, and apoapsis at approximately 15,200 km altitude in the southern hemisphere. This orbit has permitted the mapping of regional gravitational structure in the northern hemisphere, and laser altimetry from the MESSENGER spacecraft has yielded a geodetically controlled elevation model for the same hemisphere. The shape of a planet combined with gravity provides fundamental information regarding its internal structure and geologic and thermal evolution. Elevations in the northern hemisphere exhibit a unimodal distribution with a dynamic range of 9.63 km, less than that of the Moon (19.9 km), but consistent with Mercury's higher surface gravitational acceleration. After one Earth-year in orbit, refined models of gravity and topography have revealed several large positive gravity anomalies that coincide with major impact basins. These candidate mascons have anomalies that exceed 100 mGal and indicate substantial crustal thinning and superisostatic uplift of underlying mantle. An additional uncompensated 1000-km-diameter gravity and topographic high at 68 deg N, 33 deg E lies within Mercury's northern volcanic plains. Mercury's northern hemisphere crust is generally thicker at low latitudes than in the polar region. The low-degree gravity field, combined with planetary spin parameters, yields the moment of inertia C/MR2 = 0.353 +/- 0.017, where M=3.30 x 10(exp 23) kg and R=2440 km are Mercury's mass and radius, and a ratio of the moment of inertia of Mercury's solid outer shell to that of the planet of Cm/C = 0.452 +/- 0.035. One proposed model for Mercury's radial density distribution consistent with these results includes silicate crust and mantle layers overlying a dense solid (possibly Fe-S) layer, a liquid Fe-rich outer core of radius 2030 +/- 37 km, and an assumed solid inner core. Magnetic field measurements indicate a northward offset of Mercury's axial magnetic dipole from the geographic equator by 479 +/-3 km and provide evidence for a regional-scale magnetic field approximately collocated with the northern volcanic plains of possible crustal origin. These results from MESSENGER indicate a complex and asymmetric evolution of internal structure and dynamics in this end-member inner planet.

Neumann, Gregory A.; Solomon, Sean C.; Zuber, Maria T.; Phillips, Roger J.; Barnouin, Olivier; Ernst, Carolyn; Goosens, Sander; Hauck, Steven A., II; Head, James W., III; Johnson, Catherine L.; Lemoine, Frank G.; Margot, Jean-Luc; McNutt, Ralph; Mazarico, Erwan M.; Oberst, Jurgen; Peale, Stanley J.; Perry, Mark; Purucker, Michael E.; Rowlands, David D.; Torrence, Mark H.

2012-01-01

314

An absolute radius scale for Saturn's rings  

NASA Technical Reports Server (NTRS)

Radio and stellar occultation observations of Saturn's rings made by the Voyager spacecraft are discussed. The data reveal systematic discrepancies of almost 10 km in some parts of the rings, limiting some of the investigations. A revised solution for Saturn's rotation pole has been proposed which removes the discrepancies between the stellar and radio occultation profiles. Corrections to previously published radii vary from -2 to -10 km for the radio occultation, and +5 to -6 km for the stellar occultation. An examination of spiral density waves in the outer A Ring supports that the revised absolute radii are in error by no more than 2 km.

Nicholson, Philip D.; Cooke, Maren L.; Pelton, Emily

1990-01-01

315

Absolute Priority for a Vehicle in VANET  

NASA Astrophysics Data System (ADS)

In today's world, traffic jams waste hundreds of hours of our life. This causes many researchers try to resolve the problem with the idea of Intelligent Transportation System. For some applications like a travelling ambulance, it is important to reduce delay even for a second. In this paper, we propose a completely infrastructure-less approach for finding shortest path and controlling traffic light to provide absolute priority for an emergency vehicle. We use the idea of vehicular ad-hoc networking to reduce the imposed travelling time. Then, we simulate our proposed protocol and compare it with a centrally controlled traffic light system.

Shirani, Rostam; Hendessi, Faramarz; Montazeri, Mohammad Ali; Sheikh Zefreh, Mohammad

316

Note: Real-time absolute air refractometer.  

PubMed

We present a real-time absolute air refractometer benefiting from the synthetic pseudo-wavelength (SPW) method. Based on laser heterodyne interferometry, the SPW method uses three vacuum cells with specific lengths to synthesize a set of synthetic pseudo-wavelengths, by combination of which the refractive index can be determined directly without ambiguity. In addition, owing to the parallel arrangement of the vacuum cells in the optical path, the measured data can be collected simultaneously so that one measurement process can be less than 2 ms. The real-time feature makes it possible for instantaneous compensation for laser interferometers. PMID:24880432

Huang, Pei; Zhang, Jitao; Li, Yan; Wei, Haoyun

2014-05-01

317

Absolute method of measuring magnetic susceptibility  

USGS Publications Warehouse

An absolute method of standardization and measurement of the magnetic susceptibility of small samples is presented which can be applied to most techniques based on the Faraday method. The fact that the susceptibility is a function of the area under the curve of sample displacement versus distance of the magnet from the sample, offers a simple method of measuring the susceptibility without recourse to a standard sample. Typical results on a few substances are compared with reported values, and an error of less than 2% can be achieved. ?? 1959 The American Institute of Physics.

Thorpe, A.; Senftle, F.E.

1959-01-01

318

Continuum limit of electrostatic gyrokinetic absolute equilibrium  

SciTech Connect

Electrostatic gyrokinetic absolute equilibria with continuum velocity field are obtained through the partition function and through the Green function of the functional integral. The new results justify and explain the prescription for quantization/discretization or taking the continuum limit of velocity. The mistakes in the Appendix D of our earlier work [J.-Z. Zhu and G. W. Hammett, Phys. Plasmas 17, 122307 (2010)] are explained and corrected. If the lattice spacing for discretizing velocity is big enough, all the invariants could concentrate at the lowest Fourier modes in a negative-temperature state, which might indicate a possible variation of the dual cascade picture in 2D plasma turbulence.

Zhu Jianzhou [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2012-06-15

319

Absolute temperature stability of passive imaging radiometers  

NASA Astrophysics Data System (ADS)

A challenge in the development of multi-channel millimeter wave imaging radiometers is overcoming effects associated with the temperature dependence of receiver responsivity. In this paper, the stability of absolute radiation temperature measurements, made with direct and heterodyne detection radiometers, is investigated theoretically and experimentally. The agreement between theory and experiment is found to be good. Changes in measured radiation temperatures were found to be between 6 degree(s)K at 35 GHz and 145 degree(s)K at 220 GHz, for a one degree change in instrumental temperature. Suggestions are made, as to how the temperature stability of radiometers may be improved.

Salmon, Neil A.; Borrill, Jonathan R.; Gleed, David G.

1997-06-01

320

Smoking topography and abstinence in adult female smokers.  

PubMed

Preliminary evidence, within both adults and adolescents, suggests that the intensity with which cigarettes are smoked (i.e., smoking topography) is predictive of success during a cessation attempt. These reports have also shown topography to be superior compared to other variables, such as cigarettes per day, in the prediction of abstinence. The possibility that gender may influence this predictive relationship has not been evaluated but may be clinically useful in tailoring gender-specific interventions. Within the context of a clinical trial for smoking cessation among women, adult daily smokers completed a laboratory session that included a 1-hour ad libitum smoking period in which measures of topography were collected (N=135). Participants were then randomized to active medication (nicotine patch vs. varenicline) and abstinence was monitored for 4weeks. Among all smoking topography measures and all abstinence outcomes, a moderate association was found between longer puff duration and greater puff volume and continued smoking during the active 4-week treatment phase, but only within the nicotine patch group. Based on the weak topography-abstinence relationship among female smokers found in the current study, future studies should focus on explicit gender comparisons to examine if these associations are specific to or more robust in male smokers. PMID:24018226

McClure, Erin A; Saladin, Michael E; Baker, Nathaniel L; Carpenter, Matthew J; Gray, Kevin M

2013-12-01

321

Rapid Ice Flow Related Topography from ICESat Altimetry in NE Greenland  

NASA Astrophysics Data System (ADS)

Extending approximately 700 km inland from the coast of Greenland, the `Bronlund' Ice Stream in Northeast Greenland has a clear influence on the topography of the ice sheet from the coast to near the central divide. This onset of flow in this feature is associated with high rates of basal melt; flow in the interior is characterized by high strain rates in distinct shear margins. Fahnestock et al. (2001) investigated the topography and ice flow patterns in the interior based on data from SAR interferometry from Joughin et al. (2001). In this paper, we use ICESat precision laser altimetry data to examine the morphology of the shear margins of this feature. ICESat's high frequency sampling, 172 m along-track, provides consistent and accurate elevation data on the relief associated with the shear margins and surface undulations in the stream itself. The marginal shear zones and the undulating internal topography that define the ice stream are clearly illustrated by the sampling of the ICESat data. Repeat tracks obtained during ICESat's first four operational periods enable the impact of clouds on the elevation data to be minimized. The resulting pattern of ICESat tracks, supported by enhanced MODIS imagery, allows us to revisit the previous study based on interferometry, enabling us to study the dynamically generated topography using a consistently sampled set of detailed elevation profiles over large areas. Narrow marginal troughs are shown to be as much as 10 m deep over distances of a kilometer; this is pronounced topography in ice 3 km thick. The relief and extent of the marginal trough on the southeastern edge of the stream is in contrast to the less well-pronounced margin on the northwest. Significant surface undulations, with horizontal extents of approximately 3 ice thicknesses, are found where ice stream flow speeds reach 50 m/year, and change character downstream as flow speeds increase. Changes in the positions of the marginal troughs may be discernable if the ICESat instrument, or a follow-on mission, repeats the same tracks in a few years with similar accuracy.

Shuman, C. A.; Fahnestock, M. A.

2004-12-01

322

Dynamics of roll waves  

NASA Astrophysics Data System (ADS)

Roll waves are large, shock-like undulations of the free surface on a thin-film flowing on an incline. We present a unified theory for the dynamics of these waves, with the addition of bottom topography, for laminar or turbulent flows using a shallow-water-like approach. As a result of the bottom topogaphy, the steady flow can develop hydraulic jumps which greatly alter the stability of the flow. We derive a nonlinear amplitude equation in the limit of small but fast-varying bottom topography. Nonlinear dynamics of the amplitude equation reveals the pattern formation mechanism which selects the periodicity of the waves.

Mandre, Shreyas; Balmforth, Neil

2003-11-01

323

Sea-Surface Topography and Precise Geodesy From Aircraft: Applications to Coastal Oceanography  

NASA Astrophysics Data System (ADS)

Highly dynamic coastal ocean processes occur at temporal and spatial scales that cannot be captured by present or planned satellite altimeters. Space-borne gravity missions such as CHAMP, GRACE and GOCE also provide time-varying gravity and a geoidal msl reference surface at resolution that is too coarse for many coastal applications. The Naval Research Laboratory and the Naval Oceanographic Office have been testing airborne measurement techniques, gravity and altimetry, to determine sea-surface height and height anomaly at the short scales required for littoral regions. We have developed a precise local gravimetric geoid over a test region in the northern Gulf of Mexico from historical gravity data and recent airborne gravity surveys. The local geoid provides a msl reference surface with a resolution of about 10-15 km. A series of altimetry reflights over the region with time scales of 1 day to 1 year reveal a highly dynamic environment with coherent and rapidly varying sea-surface height anomalies. Although wind-driven topography may also be a factor, airborne expendable bathy-thermograph (AXBT) data collected at the same time show apparent correlation with wave-like temperature anomalies propagating up the continental slope of the Desoto Canyon. The observed variability may be responsible for some part of the long-term average topography calculated by differencing the gravimetric geoid with a satellite altimetry msl reference.

Brozena, J. M.; Childers, V. A.; Jacobs, G.; Blaha, J.; Ball, D.

2002-12-01

324

Effects of lunar topography on the near-surface dusty-plasma environment  

NASA Astrophysics Data System (ADS)

Due to interactions with the solar wind and ultraviolet radiation, the lunar surface develops a complex plasma environment, especially around features like craters and boulders. Various phenomena have been observed on the lunar surface, including dust levitation and horizontal dust transport. Dust levitation and transport could result in dust ponding, as has been observed on asteroid 433 Eros. To understand these phenomena a three-dimensional particle-in-cell (PIC) code was ran using the high-performance code, VORPAL©. The plasma environment was modeled above various topographies, including: (1) a flat surface; (2) a crater with a diameter of seven meters; (3) a 1x1x1 meter block; and (4) a system including a crater and a block. All four scenarios were modeled with changing solar angles to simulate a full days worth of plasma conditions. Dust dynamics were then modeled with a test particle approach, where individual dust grains are introduced into the PIC-modeled plasma environment. We simulated multiple lunar days of dust dynamics in order to detect net transport of the dust. To do this, we stepped through time while interpolating between solar angles to obtain plasma conditions and continuously eject charged grains off the surface to interact with the electric fields. A comparison of the effects of the various surface topographies on the dust and plasma environment will be presented.

Piquette, M. R.; Horanyi, M.; Likhanskii, A.

2013-12-01

325

Experimental results for absolute cylindrical wavefront testing  

NASA Astrophysics Data System (ADS)

Applications for Cylindrical and near-cylindrical surfaces are ever-increasing. However, fabrication of high quality cylindrical surfaces is limited by the difficulty of accurate and affordable metrology. Absolute testing of such surfaces represents a challenge to the optical testing community as cylindrical reference wavefronts are difficult to produce. In this paper, preliminary results for a new method of absolute testing of cylindrical wavefronts are presented. The method is based on the merging of the random ball test method with the fiber optic reference test. The random ball test assumes a large number of interferograms of a good quality sphere with errors that are statistically distributed such that the average of the errors goes to zero. The fiber optic reference test utilizes a specially processed optical fiber to provide a clean high quality reference wave from an incident line focus from the cylindrical wave under test. By taking measurements at different rotation and translations of the fiber, an analogous procedure can be employed to determine the quality of the converging cylindrical wavefront with high accuracy. This paper presents and discusses the results of recent tests of this method using a null optic formed by a COTS cylindrical lens and a free-form polished corrector element.

Reardon, Patrick J.; Alatawi, Ayshah

2014-09-01

326

Calern Observatory absolute declinations (Martin+, 1999)  

NASA Astrophysics Data System (ADS)

A regular observational programme with a photoelectric astrolabe have been performed at ``Observatoire du Calern" (Observatoire de la Cote d'Azur, OCA, ?=+43°44'55.011"; ?=-0h27m42.44s, Calern, Caussols, France) for the last twenty years. It has been almost fully automatized between 1984 and 1987. Since 1988 the photoelectric astrolabe was used without any modification. In addition to determining the daily orientation of the local vertical, the yearly analysis of the residuals permits to derive corrections to the used star catalogue Vigouroux et al. (1992A&AS...96..477V). A global reduction method was applied for the ASPHO observations. The new form of the equations Martin & Leister (1997A&AS..126..169M) give us the possibility of using the entire set of the observing program using data taken at two zenith distances (30° and 45°). The program contains about 41648 stars' transits of 269 different stars taken at ``Observatoire du Calern" (OCA). The reduction was based on the HIPPARCOS system. We discuss the possibility of computing absolute declinations through stars belonging simultaneously to the 30° and 45° zenith distances programmes. The absolute declination corrections were determined for 185 stars with precision of 0.027" and the value of the determined equator correction is -0.018"+/-0.005". The instrumental effects were also determined. The mean epoch is 1995.29. (1 data file).

Martin, V. A. F.; Leister, N. V.; Vigouroux, G.; Furia, M.; Journet, A.

1999-05-01

327

Absolute Spectrophotometry of 237 Open Cluster Stars  

NASA Astrophysics Data System (ADS)

We present absolute spectrophotometry of 237 stars in 7 nearby open clusters: Hyades, Pleiades, Alpha Persei, Praesepe, Coma Berenices, IC 4665, and M 39. The observations were taken using the Wampler single-channel scanner (Wampler 1966) on the Crossley 0.9m telescope at Lick Observatory from July 1973 through December 1974. 21 bandpasses spanning the spectral range 3500 Angstroms to 7780 Angstroms were observed for each star, with bandwiths ranging from 32Angstroms to 64 Angstroms. Data are standardized to the Hayes--Latham (1975) system. Our measurements are compared to filter colors on the Johnson BV, Stromgren ubvy, and Geneva U V B_1 B_2 V_1 G systems, as well as to spectrophotometry of a few stars published by Gunn, Stryker & Tinsley and in the Spectrophotometric Standards Catalog (Adelman; as distributed by the NSSDC). Both internal and external comparisons to the filter systems indicate a formal statistical accuracy per bandpass of 0.01 to 0.02 mag, with apparent larger ( ~ 0.03 mag) differences in absolute calibration between this data set and existing spectrophotometry. These data will comprise part of the spectrophotometry that will be used to calibrate the Beijing-Arizona-Taipei-Connecticut Color Survey of the Sky (see separate paper by Burstein et al. at this meeting).

Clampitt, L.; Burstein, D.

1994-12-01

328

Influence of nanophase titania topography on bacterial attachment and metabolism  

PubMed Central

Surfaces with nanophase compared to conventional (or nanometer smooth) topographies are known to have different properties of area, charge, and reactivity. Previously published research indicates that the attachment of certain bacteria (such as Pseudomonas fluorescens 5RL) is higher on surfaces with nanophase compared to conventional topographies, however, their effect on bacterial metabolism is unclear. Results presented here show that the adhesion of Pseudomonas fluorescens 5RL and Pseudomonas putida TVA8 was higher on nanophase than conventional titania. Importantly, in terms of metabolism, bacteria attached to the nanophase surfaces had higher bioluminescence rates than on the conventional surfaces under all nutrient conditions. Thus, the results from this study show greater select bacterial metabolism on nanometer than conventional topographies, critical results with strong consequences for the design of improved biosensors for bacteria detection. PMID:19337418

Park, Margaret R; Banks, Michelle K; Applegate, Bruce; Webster, Thomas J

2008-01-01

329

Ulva linza zoospore sensitivity to systematic variation of surface topography  

NASA Astrophysics Data System (ADS)

The use of surface topographical microstructure is abundant in nature. The lotus plant uses a fractal-like topography to create a highly non-wetting surface that self-cleans as water drops take dirt particles with them as they roll off. Analysis of how topography affects surface interactions offers a unique opportunity to attack a problem that affects our economy and societal health significantly. The attachment of biological material to manmade surfaces can be looked at as fouling or directed adhesion. Marine fouling on ship hulls costs the United States $600 million each year due to increased fuel usage caused by drag. Hospital-acquired methicillin-resistant Staphylococcus aureus infections cause thousands of deaths annually as a result of colonization of hospital surfaces. The lack of biocompatible synthetic surfaces for implants such as vascular grafts lead to restenosis as cells are unable to develop a natural interaction with the graft surface. In each circumstance there is much to learn about the complicated attachment process. This work expands the investigation of the role of topography in the attachment of the green fouling algae Ulva linza to poly(dimethylsiloxane) surfaces. Spore attachment density was correlated to the Wenzel roughness ratio on low surface energy, high-modulus poly(dimethylsiloxane)-grafted-silicon topographies. The role of topography on a scale less than the size of a spore was investigated on nano-roughened poly(dimethylsiloxane) elastomer surfaces. For a specific group of patterns, the spatial distribution of spores attached to topographies was quantitatively analyzed and shown to correlate with feature dimensions.

Sheats, Julian Taylor

330

Research of the Method of Local Topography Rapid Reconstructed  

NASA Astrophysics Data System (ADS)

For fast and convenient access to the environment based on the geomorphic characteristics of camouflage regional model for the complexity of topography, this article analyzes a variety of terrain modeling method’s advantages and limitations, discussed a variety of modeling methods in the set up of the study of basic on the hybrid modeling method and the integrated use of research results to generate the details of the existing landform characteristics can be controlled on all-terrain results. Generate local terrain adaptive modeling method, as a regional model disguised form with the local terrain topography of the region to adapt to a good camouflage effect.

Zhao, Minrong; Deng, Shengli; Shi, Ze

331

Airborne Lidar Simulator for the Lidar Surface Topography (LIST) Mission  

NASA Technical Reports Server (NTRS)

In 2007, the National Research Council (NRC) completed its first decadal survey for Earth science at the request of NASA, NOAA, and USGS. The Lidar Surface Topography (LIST) mission is one of fifteen missions recommended by NRC, whose primary objectives are to map global topography and vegetation structure at 5 m spatial resolution, and to acquire global surface height mapping within a few years. NASA Goddard conducted an initial mission concept study for the LIST mission in 2007, and developed the initial measurement requirements for the mission.

Yu, Anthony W.; Krainak, Michael A.; Abshire, James B.; Cavanaugh, John; Valett, Susan; Ramos-Izquierdo, Luis

2010-01-01

332

Adaptation of an Asperity Ploughing Model to Measured Roll Topographies  

NASA Astrophysics Data System (ADS)

A previously published asperity ploughing model has been adapted in order to approximate the measured as-ground roll surface topography. The model is then integrated with classical cold rolling plastic deformation equations including coupling to the lubricant film evolution through the roll bite. The friction distribution through the roll bite is thus a function of the specific details of the roll surface topography as well as the process parameters. predictions of roll force, torque and forward slip as well as sliding distance and volume of metal swept out by the asperities are then made and compared to experimental measurements for an aluminum alloy rolled on a laboratory rolling mill.

Lalli, L. A.; Malkani, H. G.; Sheu, S.

2004-06-01

333

Use of absolute and comparative performance feedback in absolute and comparative judgments and decisions  

Microsoft Academic Search

Which matters more—beliefs about absolute ability or ability relative to others? This study set out to compare the effects of such beliefs on satisfaction with performance, self-evaluations, and bets on future performance. In Experiment 1, undergraduate participants were told they had answered 20% correct, 80% correct, or were not given their scores on a practice test. Orthogonal to this manipulation,

Don A. Moore; William M. P. Klein

2008-01-01

334

Perceiving pitch absolutely: Comparing absolute and relative pitch possessors in a pitch memory task  

Microsoft Academic Search

BACKGROUND: The perceptual-cognitive mechanisms and neural correlates of Absolute Pitch (AP) are not fully understood. The aim of this fMRI study was to examine the neural network underlying AP using a pitch memory experiment and contrasting two groups of musicians with each other, those that have AP and those that do not. RESULTS: We found a common activation pattern for

Katrin Schulze; Nadine Gaab; Gottfried Schlaug

2009-01-01

335

Use of Absolute and Comparative Performance Feedback in Absolute and Comparative Judgments and Decisions  

ERIC Educational Resources Information Center

Which matters more--beliefs about absolute ability or ability relative to others? This study set out to compare the effects of such beliefs on satisfaction with performance, self-evaluations, and bets on future performance. In Experiment 1, undergraduate participants were told they had answered 20% correct, 80% correct, or were not given their…

Moore, Don A.; Klein, William M. P.

2008-01-01

336

Optical cryostat realizations at absolut System  

NASA Astrophysics Data System (ADS)

This paper describes two kinds of optical cryostats designed and manufactured at Absolut System. The first one makes use of pressurized LN2 for temperature control of a sample holder in the 80 K - 470 K temperature range. An optical window is implemented above the sample holder to allow for rugosity and 3D distortion of heterogeneous semicon sample assemblies on a wafer. The second one makes use of CRYOMECH remote motor type pulse tube cryocoolers for temperature control of the sample holder in the 3 K - 300 K temperature range. In this type of cryostats, particular attention has been paid to reduce the vibrations exported by the cooler. These 4 K ultra low vibration cryostats are used for characterization of samples via optical windows. Both designs will be presented and the performance reported.

Trollier, T.; Ravex, A.; Tanchon, J.

2014-01-01

337

Absolute Maximal Entanglement and Quantum Secret Sharing  

E-print Network

We study the existence of absolutely maximally entangled (AME) states in quantum mechanics and its applications to quantum information. AME states are characterized by being maximally entangled for all bipartitions of the system and exhibit genuine multipartite entanglement. With such states, we present a novel parallel teleportation protocol which teleports multiple quantum states between groups of senders and receivers. The notable features of this protocol are that (i) the partition into senders and receivers can be chosen after the state has been distributed, and (ii) one group has to perform joint quantum operations while the parties of the other group only have to act locally on their system. We also prove the equivalence between pure state quantum secret sharing schemes and AME states with an even number of parties. This equivalence implies the existence of AME states for an arbitrary number of parties based on known results about the existence of quantum secret sharing schemes.

Helwig, Wolfram; Riera, Arnau; Latorre, José I; Lo, Hoi-Kwong

2012-01-01

338

Absolute radiometric calibration of the Thematic Mapper  

NASA Technical Reports Server (NTRS)

Calibration data for the solar reflective bands of the Landsat-5 TM obtained from five in-flight absolute radiometric calibrations from July 1984-November 1985 at White Sands, New Mexico are presented and analyzed. Ground reflectance and atmospheric data were utilized to predict the spectral radiance at the entrance pupil of the TM and the average number of digital counts in each TM band. The calibration of each of the TM solar reflective bands was calculated in terms of average digital counts/unit spectral radiance for each band. It is observed that for the 12 reflectance-based measurements the rms variation from the means as a percentage of the mean is + or - 1.9 percent; for the 11 measurements in the IR bands, it is + or - 3.4 percent; and the rms variation for all 23 measurements is + or - 2.8 percent.

Slater, P. N.; Biggar, S. F.; Holm, R. G.; Jackson, R. D.; Mao, Y.

1986-01-01

339

Absolute astrometry in the next 50 years  

E-print Network

With ESA's astrometry satellite Gaia in orbit since December 2013 it is time to look at the future of fundamental astrometry and a time frame of 50 years is needed in this matter. A dozen science issues for a Gaia successor mission in twenty years are presented and in this context the possibilities for absolute astrometry with mas or sub-mas accuracies are discussed. The three powerful techniques: VLBI, the MICADO camera on the E-ELT, and the LSST are described and documented by literature references and by an extensive correspondence with leading astronomers who readily responded with all the information I needed. In brief, the two Gaia-like missions would provide an astrometric foundation for all branches of astronomy from the solar system and stellar systems to compact galaxies, quasars and dark matter by data which cannot be surpassed in the next 50 years.

Høg, Erik

2014-01-01

340

Measured and modelled absolute gravity in Greenland  

NASA Astrophysics Data System (ADS)

Present day changes in the ice volume in glaciated areas like Greenland will change the load on the Earth and to this change the lithosphere will respond elastically. The Earth also responds to changes in the ice volume over a millennial time scale. This response is due to the viscous properties of the mantle and is known as Glaical Isostatic Adjustment (GIA). Both signals are present in GPS and absolute gravity (AG) measurements and they will give an uncertainty in mass balance estimates calculated from these data types. It is possible to separate the two signals if both gravity and Global Positioning System (GPS) time series are available. DTU Space acquired an A10 absolute gravimeter in 2008. One purpose of this instrument is to establish AG time series in Greenland and the first measurements were conducted in 2009. Since then are 18 different Greenland GPS Network (GNET) stations visited and six of these are visited more then once. The gravity signal consists of three signals; the elastic signal, the viscous signal and the direct attraction from the ice masses. All of these signals can be modelled using various techniques. The viscous signal is modelled by solving the Sea Level Equation with an appropriate ice history and Earth model. The free code SELEN is used for this. The elastic signal is modelled as a convolution of the elastic Greens function for gravity and a model of present day ice mass changes. The direct attraction is the same as the Newtonian attraction and is calculated as this. Here we will present the preliminary results of the AG measurements in Greenland. We will also present modelled estimates of the direct attraction, the elastic and the viscous signals.

Nielsen, E.; Forsberg, R.; Strykowski, G.

2012-12-01

341

Interaction of dipolar vortices with a step-like topography  

NASA Astrophysics Data System (ADS)

The interaction of a barotropic, dipolar vortex with a step-like topography is studied by means of laboratory experiments in a rotating tank and by numerical simulations based on a quasi-two-dimensional model. Two main configurations are analyzed: when the dipole approaches a "low" or a "high" step with respect to the maximum water depth. For relatively low steps, the vortex crosses the topography with a deflected trajectory, while maintaining its dipolar structure. The sense of this deflection depends on whether the dipole reaches a step-up or a step-down. For high steps, in contrast, the dipole is not able to cross the topography, and the reflection of one of the dipole structures is observed. In both cases, one observes a weak flow along the topography with shallow water on its right. The essential features of the flow evolution for low and high steps can be explained by using arguments of potential vorticity conservation (due to the weakness of viscous effects). In order to determine whether a barotropic dipole is able to cross the step or is reflected, qualitative criteria based on the step height and dipole strength are derived using inviscid arguments.

Tenreiro, M.; Zavala Sansón, L.; van Heijst, G. J. F.

2006-05-01

342

Evidence from gravity and topography data for folding of Tibet  

Microsoft Academic Search

Bouguer gravity and topography data from Tibet suggest that the surface of the plateau and the subsurface density interfaces are warped into two series of ridges and troughs trending parallel to the collision zone with wavelengths of 150 and 500 km. These folds are superimposed on an overall state of isostatic compensation owing to crustal thickening. Such folding is predicted

Yu Jin; Marcia K. McNutt; Yongsheng Zhu

1994-01-01

343

Estimates of Martian crustal thickness from viscous relaxation of topography  

Microsoft Academic Search

Isostatically compensated crustal thickness variations and associated topographic contrasts at the surface of a planet result in lateral pressure gradients, which may cause the lower crust to flow and reduce the relief. Areas of thicker crust are generally associated with more rapid relaxation of topography. On Mars, topographic features such as impact basins and the hemispheric dichotomy have survived for

F. Nimmo; D. J. Stevenson

2001-01-01

344

Geophysical implications of the longwavelength topography of Rhea  

E-print Network

Geophysical implications of the longwavelength topography of Rhea F. Nimmo,1 B. G. Bills,2 P. C. Citation: Nimmo, F., B. G. Bills, P. C. Thomas, and S. W. Asmar (2010), Geophysical implications; Nimmo et al., 2007], impact cratering [e.g., Thomas et al., 2002], flexure [Luttrell and Sandwell, 2006

Nimmo, Francis

345

Topography within the axial channels of Monterey and Soquel Canyons  

Microsoft Academic Search

Ultrahigh resolution surveys have been conducted that outline the topography and near seafloor structure within the axial channels of Monterey and Soquel Canyons. Multibeam bathymetry (vertical precision of 0.15 m and horizontal resolution of 1.0 m at 50 m survey altitude) were collected using an autonomous underwater vehicle (AUV). An inertial navigation system combined with a doppler velocity sonar allows

E. Lundsten; C. K. Paull; D. W. Caress; W. Ussler; H. Thomas

2009-01-01

346

An anatomical and functional topography of human auditory cortical areas  

PubMed Central

While advances in magnetic resonance imaging (MRI) throughout the last decades have enabled the detailed anatomical and functional inspection of the human brain non-invasively, to date there is no consensus regarding the precise subdivision and topography of the areas forming the human auditory cortex. Here, we propose a topography of the human auditory areas based on insights on the anatomical and functional properties of human auditory areas as revealed by studies of cyto- and myelo-architecture and fMRI investigations at ultra-high magnetic field (7 Tesla). Importantly, we illustrate that—whereas a group-based approach to analyze functional (tonotopic) maps is appropriate to highlight the main tonotopic axis—the examination of tonotopic maps at single subject level is required to detail the topography of primary and non-primary areas that may be more variable across subjects. Furthermore, we show that considering multiple maps indicative of anatomical (i.e., myelination) as well as of functional properties (e.g., broadness of frequency tuning) is helpful in identifying auditory cortical areas in individual human brains. We propose and discuss a topography of areas that is consistent with old and recent anatomical post-mortem characterizations of the human auditory cortex and that may serve as a working model for neuroscience studies of auditory functions. PMID:25120426

Moerel, Michelle; De Martino, Federico; Formisano, Elia

2014-01-01

347

Mars Mantle (MOHO) Topography with Mantle Elevation Texture Map  

NSDL National Science Digital Library

This site from NASA features a rotating animation of Mars using data from Mars Orbiting Laser Altimeter (MOLA). The topography is colored to indicate elevation. Additionally, an image highlighting the mantle is colored to indicate its elevation. A flat version of this same dataset is also available.

Studio, Nasa/goddard S.; Nasa

348

SWOT: The Surface Water & Ocean Topography Satellite Mission  

E-print Network

SWOT: The Surface Water & Ocean Topography Satellite Mission Doug Alsdorf Byrd Polar Research Arctic Lakes, Science, 2005 Arctic lakes are losing storage, despite a slight increase in precipitation of Oceans ECCO-2 MIT JPL ocean current model Although altimetry data have significantly advanced the study

349

The Global Multi-Resolution Topography (GMRT) Synthesis  

Microsoft Academic Search

Topographic maps provide a backdrop for research in nearly every earth science discipline. There is particular demand for bathymetry data in the ocean basins, where existing coverage is sparse. Ships and submersibles worldwide are rapidly acquiring large volumes of new data with modern swath mapping systems. The science community is best served by a global topography compilation that is easily

R. Arko; W. Ryan; S. Carbotte; A. Melkonian; J. Coplan; S. O'Hara; D. Chayes; R. Weissel; A. Goodwillie; V. Ferrini; K. Stroker; W. Virden

2007-01-01

350

Plasma Molding over Surface Topography: IED and IAD over Steps  

Microsoft Academic Search

Plasma molding over surface topography finds applications in MEMS microfabrication, plasma extraction through grids, and plasma contact with internal reactor parts (e.g., wafer chuck edge). The flux, energy and angular distributions of ions incident on the target are of primary importance in these applications. These quantities depend critically on the shape of the meniscus (plasma-sheath boundary) formed over the surface

Demetre Economou; Doosik Kim

2001-01-01

351

Global Topography of Titan from Cassini RADAR Data (Invited)  

NASA Astrophysics Data System (ADS)

Cassini RADAR data are used to construct a global, albeit sparsely-sampled, topography map, and to generate a hypsometric profile to compare with other planetary bodies. Titan’s hypsogram is unimodal and strikingly narrow compared with the terrestrial planets. To investigate topographic extremes, a novel variant on the classic hypsogram is introduced, with a logarithmic abscissa to highlight mountainous terrain. In such a plot, the top of the terrestrial hypsogram is quite distinct from those of Mars and Venus due to the ‘glacial buzz-saw’ that clips terrestrial topography above the snowline. In contrast to the positive skew seen in other hypsograms, with a long tail of positive relief due to mountains, there is an indication (weak, given the limited data for Titan so far) that the Titan hypsogram appears slightly negatively skewed, suggesting a significant population of unfilled depressions. Limited data permit only a simplistic comparison of Titan topography with other icy satellites but we find that the standard deviation of terrain height (albeit at different scales) is similar to those of Ganymede and Europa. The topography of terrestrial planets is sampled with the same coverage that we have for Titan to gauge what as-yet-undiscovered topographic surprises may yet be hidden by Titan’s haze.

Lorenz, R. D.; Cassini RADAR Team

2010-12-01

352

The Lang method of X-ray diffraction topography  

Microsoft Academic Search

The paper sets forth the basic principles of the Lang method of X-ray diffraction topography for the investigation of imperfections in crystals. Main Techniques for its experimental implementation are described, and relations and procedures used in the interpretation of the topograms are examined. The problem of resolution is analyzed along with the main factors determining contrast at dislocations. Some of

R. Fiedler; M. Polcarova

1975-01-01

353

Some Bristol Prague explorations in x-ray topography  

Microsoft Academic Search

This paper briefly chronicles a long-standing and productive collaboration between the Institute of Physics, Czech Academy of Science and the H H Wills Physics Laboratory. It began in early 1962 with a brief visit to Bristol by Milena Polcarová. The initial aim, successfully achieved, was the mapping by transmission topography of dislocations in melt-grown single crystals of a Fe Si

A. R. Lang

2005-01-01

354

Stroboscopic X-Ray Topography of Surface Acoustic Wave Devices  

Microsoft Academic Search

X-ray topography can be used to obtain images of microscopic strains in single crystals. inely applied to the characterisation of defects such as dislocations and low angle grain boundaries. Pre- vious studies have shown that the average strain fields associated with travelling surface waves can be imaged on an x-ray topograph, together with the defects in the crystal substrate. This

R. W. Whatmore; P. A. Goddard; B. K. Tanner

1982-01-01

355

Extraction of Martian valley networks from digital topography  

E-print Network

are inferred from digital topography by an autonomous computer algorithm as drainage networks, instead of being. Slopes of ``streams'' in Martian valley networks decrease downstream at a slower rate than slopes resemblance gave rise to an early suggestion [Masursky, 1973; Milton, 1973] of a common origin of VNs

Stepinski, Tomasz F.

356

Tidal Conversion by Supercritical Topography NEIL J. BALMFORTH  

E-print Network

of internal waves as the barotropic tide flows over topography on the ocean floor has lately received wide that the breaking of such waves could play an important role in setting up large-scale ocean circula- tion (Munk, Massachusetts (Manuscript received 22 May 2008, in final form 20 January 2009) ABSTRACT Calculations

Balmforth, Neil

357

Very high-resolution mapping of river-immersed topography  

E-print Network

techniques used for river bathymetry are reviewed. Frequently, these techniques have been developedVery high-resolution mapping of river-immersed topography by remote sensing Denis Feurer,1,2 * Jean cases: inaccessible rivers, large-scale depth mapping, very shallow rivers. The remote sensing

Paris-Sud XI, Université de

358

Generation of internal undular bores by transcritical flow over topography  

E-print Network

Generation of internal undular bores by transcritical flow over topography R.H.J. Grimshaw1 , D. H propagating internal solitary waves. Often these waves appear as a wave-train, or undular bore description of undular bores, for flow over isolated obstacles and for flow over a step. 1 Introduction

359

Invariance of operant topography throughout changes in motivational conditions  

Microsoft Academic Search

To determine the extent that distribution of responses established through reinforcement contingencies would be affected by motivational changes, 11 male rats were trained to manipulate a lever that could be displaced in any of 8 directions within a circular aperture. Both frequency (total number of contacts) and response topography (frequency of contact at various positions) were recorded. Groups were tested

Charles D. Corman; Raymond C. Miles

1966-01-01

360

Short wavelength topography on the inner-core boundary  

PubMed Central

Constraining the topography of the inner-core boundary is important for studies of core–mantle coupling and the generation of the geodynamo. We present evidence for significant temporal variability in the amplitude of the inner core reflected phase PKiKP for an exceptionally high-quality earthquake doublet, observed postcritically at the short-period Yellowknife seismic array (YK), which occurred in the South Sandwich Islands within a 10-year interval (1993/2003). This observation, complemented by data from several other doublets, indicates the presence of topography at the inner-core boundary, with a horizontal wavelength on the order of 10 km. Such topography could be sustained by small-scale convection at the top of the inner core and is compatible with a rate of super rotation of the inner core of ?0.1–0.15° per year. In the absence of inner-core rotation, decadal scale temporal changes in the inner-core boundary topography would provide an upper bound on the viscosity at the top of the inner core. PMID:17190798

Cao, Aimin; Masson, Yder; Romanowicz, Barbara

2007-01-01

361

Corneal topography of photorefractive keratectomy versus laser in situ keratomileusis  

Microsoft Academic Search

ObjectiveThis study aimed to compare qualitative patterns of corneal topography early in the postoperative course after excimer laser photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) when used for the treatment of myopia of 6.0 to 15.0 diopters.

Peter S Hersh; Kevin S Scher; Rashna Irani

1998-01-01

362

THE INFLUENCE OF TOPOGRAPHY AND TEMPERATURE ON QUERCUS ILICIFOLIA SUCCESSION  

E-print Network

and tree oak plot. I found that colder microclimates are created by the effects of the low topography as well as by the unique structure of the low scrub oak canopy. Data shows that these microclimates oak thickets can become widespread due to forest fires (Mouw 2000). The landscape of Martha's Vineyard

Vallino, Joseph J.

363

Nanoscale surface topography reshapes neuronal growth in culture  

E-print Network

that contrasts with the complex tri-dimensional topography of the embryonic brain1 . Moreover, cellular adhesion on the micrometric2 and ever sub-micrometric scale3 . Understanding the mechanisms of cell adhesion might therefore spaced adhesive gold nanoparticles to demonstrate that cell spreading is an active process controlled

Boyer, Edmond

364

Rapid topography mapping of scalar fields: large molecular clusters.  

PubMed

An efficient and rapid algorithm for topography mapping of scalar fields, molecular electron density (MED) and molecular electrostatic potential (MESP) is presented. The highlight of the work is the use of fast function evaluation by Deformed-atoms-in-molecules (DAM) method. The DAM method provides very rapid as well as sufficiently accurate function and gradient evaluation. For mapping the topography of large systems, the molecular tailoring approach (MTA) is invoked. This new code is tested out for mapping the MED and MESP critical points (CP's) of small systems. It is further applied to large molecular clusters viz. (H(2)O)(25), (C(6)H(6))(8) and also to a unit cell of valine crystal at MP2/6-31+G(d) level of theory. The completeness of the topography is checked by extensive search as well as applying the Poincaré-Hopf relation. The results obtained show that the DAM method in combination with MTA provides a rapid and efficient route for mapping the topography of large molecular systems. PMID:22920112

Yeole, Sachin D; López, Rafael; Gadre, Shridhar R

2012-08-21

365

Moire Topography For The Detection Of Orthopaedic Defects  

NASA Astrophysics Data System (ADS)

Moire topography is applied for the follow-up of scoliosis patients. The results are then compared with the X-rays. A special lamp and scale arrangement is utilized for patient alignment. It is suggested that this technique will be used for the detection of all orthopaedic defects.

Kamal, Syed A.; Lindseth, Richard E.

1981-02-01

366

Controls of initial topography on temporal and spatial patterns of glacial erosion  

NASA Astrophysics Data System (ADS)

Here we investigate the influence of initial pre-glacial topography on spatial and temporal patterns of glacial erosion using numerical surface process modelling, including a higher order ice sheet model. First, we consider glacier dynamics when simulating glaciation in two real landscapes, representing plateau-type topography (southeast Australia) and characteristic steady-state fluvial topography (southern Taiwan). We find that the different initial landscape configurations result in distinctly different ice configurations and patterns of basal sliding. The sliding patterns are controlled by ice configuration and the resulting basal shear stresses and by the thermal properties at the base of the ice. We then investigate how these characteristic patterns of basal sliding control glacial erosion and long-term landscape evolution using synthetic representations of the two landscapes. The two landscape configurations result in markedly different spatial and temporal patterns of glacial erosion. However, the resulting landscapes may have similar morphology, irrespective of initial landscapes and glacial erosion patterns being significantly different. The numerical experiments also suggest that, in addition to basal temperature, basal shear stress is important in restricting long-term glacial erosion, which is relevant for the preservation of landforms during glaciations. Specifically, pre-glacial landforms may be eroded although they are initially protected by cold-based ice, when the ice configuration promotes significant basal shear stress (glacial erosion) at the edge of a plateau-like landscape. In contrast, pre-glacial landforms may be preserved irrespective of the ice being warm-based, when low gradients in the ice surface act to limit basal shear stress.

Pedersen, Vivi K.; Huismans, Ritske S.; Herman, Frédéric; Egholm, David L.

2014-10-01

367

COMMUNICATIONS Determination of absolute photoionization cross sections  

E-print Network

spectrometry has recently been implemented as a flame diagnostic technique, in which the chemical constituents of California, Berkeley, California 94720 and Chemical Sciences Division, Lawrence Berkeley National Laboratory use in chemical dynamics experi- ments. Photodissociation and bimolecular scattering experi- ments

Neumark, Daniel M.

368

Influence of lunar topography on simulated surface temperature  

NASA Astrophysics Data System (ADS)

The surface temperature of the Moon is one of the essential parameters for the lunar exploration, especially to evaluate the Moon thermophysical features. The distribution of the temperature is heavily influenced by the Moon topography, which, however, is rarely studied in the state-of-art surface temperature models. Therefore, this paper takes the Moon topography into account to improve the surface temperature model, Racca model. The main parameters, such as slopes along the longitude and latitude directions, are estimated with the topography data from Chang'E-1 satellite and the Horn algorithm. Then the effective solar illumination model is then constructed with the slopes and the relative position to the subsolar point. Finally, the temperature distribution over the Moon surface is obtained with the effective illumination model and the improved Racca model. The results indicate that the distribution of the temperature is very sensitive to the fluctuation of the Moon surface. The change of the surface temperature is up to 150 K in some places compared to the result without considering the topography. In addition, the variation of the surface temperature increases with the distance from the subsolar point and the elevation, along both latitude and longitude directions. Furthermore, the simulated surface temperature coincides well with the brightness temperature in 37 GHz observed by the microwave sounder onboard Chang'E-2 satellite. The corresponded emissivity map not only eliminates the influence of the topography, but also hints the inherent properties of the lunar regolith just below the surface. Last but not the least, the distribution of the permanently shadowed regions (PSRs) in the lunar pole area is also evaluated with the simulated surface temperature result.

Zhiguo, Meng; Yi, Xu; Zhanchuan, Cai; Shengbo, Chen; Yi, Lian; Hang, Huang

2014-11-01

369

Absolute quantification of protein copy number using a single-molecule-sensitive microarray.  

PubMed

We report the use of a microfluidic microarray incorporating single molecule detection for the absolute quantification of protein copy number in solution. In this paper we demonstrate protocols which enable calibration free detection for two protein detection assays. An EGFP protein assay has a limit of detection of <30 EGFP proteins in a microfluidic analysis chamber (limited by non-specific background binding), with a measured limit of linearity of approximately 6 × 10(6) molecules of analyte in the analysis chamber and a dynamic range of >5 orders of magnitude in protein concentration. An antibody sandwich assay was used to detect unlabelled human tumour suppressor protein p53 with a limit of detection of approximately 21 p53 proteins and a dynamic range of >3 orders of magnitude. We show that these protocols can be used to calibrate data retrospectively to determine the absolute protein copy number at the single cell level in two human cancer cell lines. PMID:24676423

Burgin, Edward; Salehi-Reyhani, Ali; Barclay, Michael; Brown, Aidan; Kaplinsky, Joseph; Novakova, Miroslava; Neil, Mark A A; Ces, Oscar; Willison, Keith R; Klug, David R

2014-07-01

370

Gravity studies at Etna volcano: a comparison between relative and absolute gravity measurements  

NASA Astrophysics Data System (ADS)

The INGV has been operating at Mt Etna a discrete gravity network since 1986 and three continuous gravity stations since 1998. The combined use of discrete and continuous gravity measurements has provided, through the detection of phenomena with a wide range of evolution rates (periods ranging from minutes to years), both substantial improvements in the knowledge of the dynamics of the shallow plumbing system at Etna and the identification of any gravity transient before and during the last volcanic eruptions. Recently, with the aim of compare relative microgravity measurements routinely acquired on Etna volcano using spring gravimeters with absolute gravity observations, we performed two surveys in June 2007 and July 2008 by using the new IMGC-02 transportable absolute gravimeter. The IMGC-02 transportable instrument, developed by INRiM - Torino, adopts the absolute ballistic method, which was recognized at international level (Comité International des Poids et Mesures - CIPM) as primary method of measurement of the acceleration due to gravity. Taking into account the logistic situation of Etna, four absolute gravity stations were settled in 2007, while a fifth station was installed in 2008. Four of them were located very close to the active craters at: (i) the Serra la Nave Astrophysical Observatory (1740 m a.s.l.); (ii) the Montagnola (2500 m a.s.l.); (iii) the Pizzi Deneri Volcanological Observatory (2810 m a.s.l.); and the newest (iv) the Caserma Donnavita (1250 m a.s.l.). One absolute station was installed out of the volcanic area, inside the gravity laboratory of INGV - Catania, to be adopted as reference. We present the results obtained by comparing relative and absolute gravity measurements and their implications on the latest Etna eruption started on 13th May 2008.

Greco, F.; D'Agostino, G.; Del Negro, C.; Germak, A.; Sicali, A.; Vitiello, F.

2008-12-01

371

Issues in Absolute Spectral Radiometric Calibration: Intercomparison of Eight Sources  

NASA Technical Reports Server (NTRS)

The application of atmospheric models to AVIRIS and other spectral imaging data to derive surface reflectance requires that the sensor output be calibrated to absolute radiance. Uncertainties in absolute calibration are to be expected, and claims of 92% accuracy have been published. Measurements of accurate surface albedos and cloud absorption to be used in radiative balance calculations depend critically on knowing the absolute spectral-radiometric response of the sensor. The Earth Observing System project is implementing a rigorous program of absolute radiometric calibration for all optical sensors. Since a number of imaging instruments that provide output in terms of absolute radiance are calibrated at different sites, it is important to determine the errors that can be expected among calibration sites. Another question exists about the errors in the absolute knowledge of the exoatmospheric spectral solar irradiance.

Goetz, Alexander F. H.; Kindel, Bruce; Pilewskie, Peter

1998-01-01

372

Radiation and dissipation of internal waves generated by geostrophic motions impinging on small-scale topography  

E-print Network

Observations and inverse models suggest that small-scale turbulent mixing is enhanced in the Southern Ocean in regions above rough topography. The enhancement extends 1 km above the topography suggesting that mixing is ...

Nikurashin, Maxim (Maxim Anatolevich)

2009-01-01

373

Positioning, alignment and absolute pointing of the ANTARES neutrino telescope  

NASA Astrophysics Data System (ADS)

A precise detector alignment and absolute pointing is crucial for point-source searches. The ANTARES neutrino telescope utilises an array of hydrophones, tiltmeters and compasses for the relative positioning of the optical sensors. The absolute calibration is accomplished by long-baseline low-frequency triangulation of the acoustic reference devices in the deep-sea with a differential GPS system at the sea surface. The absolute pointing can be independently verified by detecting the shadow of the Moon in cosmic rays.

Fehr, F.; Distefano, C.; Antares Collaboration

2010-01-01

374

Absolute luminosity measurements with the LHCb detector at the LHC  

Microsoft Academic Search

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of

R. Aaij; B. Adeva; M. Adinolfi; C. Adrover; A. Affolder; Z. Ajaltouni; J. Albrecht; F. Alessio; M. Alexander; G. Alkhazov; P. Alvarez Cartelle; A. A. Alves Jr; S. Amato; Y. Amhis; J. Anderson; R. B. Appleby; O. Aquines Gutierrez; F. Archilli; L. Arrabito; A. Artamonov; M. Artuso; E. Aslanides; G. Auriemma; S. Bachmann; J. J. Back; D. S. Bailey; V. Balagura; W. Baldini; R. J. Barlow; C. Barschel; S. Barsuk; W. Barter; A. Bates; C. Bauer; Th. Bauer; A. Bay; I. Bediaga; K. Belous; I. Belyaev; E. Ben-Haim; M. Benayoun; G. Bencivenni; S. Benson; J. Benton; R. Bernet; M van Beuzekom; A. Bien; S. Bifani; A. Bizzeti; P. M. Bjørnstad; T. Blake; F. Blanc; C. Blanks; J. Blouw; S. Blusk; A. Bobrov; V. Bocci; A. Bondar; N. Bondar; W. Bonivento; S. Borghi; A. Borgia; T. J. V. Bowcock; C. Bozzi; T. Brambach; J. van den Brand; J. Bressieux; D. Brett; S. Brisbane; M. Britsch; T. Britton; N. H. Brook; H. Brown; A. Büchler-Germann; I. Burducea; A. Bursche; J. Buytaert; S. Cadeddu; J. M. Caicedo Carvajal; O. Callot; M. Calvi; M. Calvo Gomez; A. Camboni; P. Campana; A. Carbone; G. Carboni; R. Cardinale; A. Cardini; L. Carson; K. Carvalho Akiba; G. Casse; M. Cattaneo; M. Charles; Ph. Charpentier; N. Chiapolini; K. Ciba; X. Cid Vidal; G. Ciezarek; P. E. L. Clarke; M. Clemencic; H. V. Cliff; J. Closier; C. Coca; V. Coco; J. Cogan; P. Collins; F. Constantin; G. Conti; A. Contu; A. Cook; M. Coombes; G A Cowan; R. Currie; B. D'Almagne; C. D'Ambrosio; P. David; I. De Bonis; S. De Capua; M. De Cian; F. De Lorenzi; J. M. De Miranda; L. De Paula; P. De Simone; D. Decamp; M. Deckenhoff; H. Degaudenzi; M. Deissenroth; L. Del Buono; C. Deplano; O. Deschamps; F. Dettori; J. Dickens; H. Dijkstra; P. Diniz Batista; S. Donleavy; F. Dordei; A. Dosil Suárez; D. Dossett; A. Dovbnya; F. Dupertuis; R. Dzhelyadin; C. Eames; S. Easo; U. Egede; V. Egorychev; S. Eidelman; D. van Eijk; F. Eisele; S. Eisenhardt; R. Ekelhof; L. Eklund; Ch. Elsasser; D. G. d'Enterria; D. Esperante Pereira; L. Estève; A. Falabella; E. Fanchini; C. Färber; G. Fardell; C. Farinelli; S. Farry; V. Fave; V. Fernandez Albor; M. Ferro-Luzzi; S. Filippov; C. Fitzpatrick; M. Fontana; F. Fontanelli; R. Forty; M. Frank; C. Frei; M. Frosini; S. Furcas; A. Gallas Torreira; D. Galli; M. Gandelman; P. Gandini; Y. Gao; J. C. Garnier; J. Garofoli; J. Garra Tico; L. Garrido; C. Gaspar; N. Gauvin; M. Gersabeck; T. Gershon; Ph. Ghez; V V Gligorov; C. Göbel; D. Golubkov; A. Golutvin; A. Gomes; H. Gordon; M. Grabalosa Gándara; R. Graciani Diaz; L. A. Granado Cardoso; E. Graugés; G. Graziani; A. Grecu; S. Gregson; B. Gui; E. Gushchin; Yu. Guz; T. Gys; G. Haefeli; C. Haen; S. C. Haines; T. Hampson; S. Hansmann-Menzemer; R. Harji; N. Harnew; J. Harrison; P. F. Harrison; J. He; V. Heijne; K. Hennessy; P. Henrard; J. A. Hernando Morata; E. van Herwijnen; E. Hicks; W. Hofmann; K. Holubyev; P. Hopchev; W. Hulsbergen; P. Hunt; T. Huse; R. S. Huston; D. Hutchcroft; D. Hynds; V. Iakovenko; P. Ilten; J. Imong; R. Jacobsson; A. Jaeger; M. Jahjah Hussein; E. Jans; F. Jansen; P. Jaton; B. Jean-Marie; F. Jing; M. John; D. Johnson; C. R. Jones; B. Jost; S. Kandybei; M. Karacson; T. M. Karbach; J. Keaveney; U. Kerzel; T. Ketel; A. Keune; B. Khanji; Y. M. Kim; M. Knecht; S. Koblitz; P. Koppenburg; A. Kozlinskiy; L. Kravchuk; K. Kreplin; M. Kreps; G. Krocker; P. Krokovny; F. Kruse; K. Kruzelecki; M. Kucharczyk; S. Kukulak; R. Kumar; T. Kvaratskheliya; V. N. La Thi; D. Lacarrere; G. Lafferty; A. Lai; D. Lambert; R. W. Lambert; E. Lanciotti; G. Lanfranchi; C. Langenbruch; T. Latham; R. Le Gac; J. van Leerdam; J.-P. Lees; R. Lefèvre; A. Leflat; J. Lefrançois; O. Leroy; T. Lesiak; L. Li; L. Li Gioi; M. Lieng; M. Liles; R. Lindner; C. Linn; B. Liu; G. Liu; J. H. Lopes; E. Lopez Asamar; N. Lopez-March; J. Luisier; F. Machefert; I. V. Machikhiliyan; F. Maciuc; O. Maev; J. Magnin; S. Malde; R. M. D. Mamunur; G Mancinelli; N. Mangiafave; U. Marconi; R. Märki; J. Marks; G. Martellotti; A. Martens; L. Martin; A. Martín Sánchez; D. Martinez Santos; A. Massafferri; R. Matev; Z. Mathe; C. Matteuzzi; M. Matveev; E. Maurice; B. Maynard; A. Mazurov; G. McGregor; R. McNulty; C. Mclean; M. Meissner; M. Merk; J. Merkel; R. Messi; S. Miglioranzi; D. A. Milanes; M.-N. Minard; S. Monteil; D. Moran; P. Morawski; I. Mous; F. Muheim; K. Müller; R. Muresan; B. Muryn; M. Musy; J. Mylroie-Smith; P. Naik; T. Nakada; R. Nandakumar; J. Nardulli; I. Nasteva; M Needham; N. Neufeld; C. Nguyen-Mau; M. Nicol; S. Nies; V. Niess; N. Nikitin; A. Oblakowska-Mucha; V. Obraztsov; S. Oggero; S. Ogilvy; O. Okhrimenko; R. Oldeman; M. Orlandea; J. M. Otalora Goicochea; P. Owen; B. Pal; J. Palacios; M. Palutan; J. Panman; A. Papanestis; M. Pappagallo; C J Parkinson; G. Passaleva; G. D. Patel; M. Patel; S. K. Paterson; G. N. Patrick; C Pavel-Nicorescu; A. Pazos Alvarez; A. Pellegrino; G. Penso

2011-01-01

375

Absolute nuclear material assay using count distribution (LAMBDA) space  

DOEpatents

A method of absolute nuclear material assay of an unknown source comprising counting neutrons from the unknown source and providing an absolute nuclear material assay utilizing a model to optimally compare to the measured count distributions. In one embodiment, the step of providing an absolute nuclear material assay comprises utilizing a random sampling of analytically computed fission chain distributions to generate a continuous time-evolving sequence of event-counts by spreading the fission chain distribution in time.

Prasad, Manoj K. (Pleasanton, CA); Snyderman, Neal J. (Berkeley, CA); Rowland, Mark S. (Alamo, CA)

2012-06-05

376

Absolute quantum energy inequalities in curved spacetime  

E-print Network

Quantum Energy Inequalities (QEIs) are results which limit the extent to which the smeared renormalised energy density of the quantum field can be negative, when averaged along a timelike curve or over a more general timelike submanifold in spacetime. On globally hyperbolic spacetimes the minimally-coupled massive quantum Klein--Gordon field is known to obey a `difference' QEI that depends on a reference state chosen arbitrarily from the class of Hadamard states. In many spacetimes of interest this bound cannot be evaluated explicitly. In this paper we obtain the first `absolute' QEI for the minimally-coupled massive quantum Klein--Gordon field on four dimensional globally hyperbolic spacetimes; that is, a bound which depends only on the local geometry. The argument is an adaptation of that used to prove the difference QEI and utilises the Sobolev wave-front set to give a complete characterisation of the singularities of the Hadamard series. Moreover, the bound is explicit and can be formulated covariantly under additional (general) conditions. We also generalise our results to incorporate adiabatic states.

Christopher J. Fewster; Calvin J. Smith

2007-02-09

377

Optimizing an Absolute Gravimeter Comparison Schedule  

NASA Astrophysics Data System (ADS)

Since 1980 various groups have executed comparisons of absolute gravimeters for the purpose of determining the accuracy of operational meters. While the final method of processing data and estimating meter accuracy has varied from comparison to comparison, one common fact has persisted - two meters can not observe gravity at both the same time and the same place. With this simple fact in mind, and despite variations in the final method of data processing, it has always been necessary to develop an efficient observation schedule for a comparison. Such a schedule must obviously depend on the number of meters in attendance and number of observing piers available. But other factors must be considered, such as how many observations each meter is required to make, how many times a meter compares to another meter and how many times a meter compares to itself - all of which effect the conditioning of the equation system. Finding the most efficient schedule with the greatest conditioning of the equation system is a problem of optimization. The number of possible combinations for even small numbers of meters and piers grows exponentially out of computational possibility if a brute force method is used. This talk discusses an efficient solution to forming such an optimized schedule, and a fast computer program which makes use of this solution.

Smith, D. A.; Saleh, J.; Eckl, M. C.

2013-12-01

378

Absolute number concentration measurement of submicrometer particles  

SciTech Connect

Condensation nuclei in the atmosphere are known to be an important factor in the development of clouds, the occurrence of rainfall, and the formation of particulate air pollutions that can cause undesirable effects on man and his environment. Condensation nuclei are invisible and numerous, and their number concentration has become the characteristic of interest and has been widely studied since the development of the first condensation nuclei counter by Aitken in 1888. A conventional nuclei counter employs the so-called condensation technique which enables the minute nuclei to grow, in a supersaturated environment, to ..mu..m-sized droplets; the number concentration of the visible droplets is then measured. Since each nucleus grows to a droplet, the number concentration of droplets and nuclei remains the same. The number of droplets is measured by (1) direct observation with a microscope (direct counter), (2) counting from photographs of the droplets (photographic counter), (3) suitably calibrated light transmission (or scattering) measurement (relative photoelectric counter). Most of the widely-used counters are relative counters in which the instrument reading must be calibrated against a direct or photographic counter. A new condensation nuclei counter is described which is designed to have the following advantages over the widely-used counters: (a) It provides an absolute concentration measurement. (b) Even a small random fluctuation of nuclei concentration can immediately be detected.

Chen, T.H.B.

1982-01-01

379

Absolute spacetime: the twentieth century ether  

E-print Network

All gauge theories need ``something fixed'' even as ``something changes.'' Underlying the implementation of these ideas all major physical theories make indispensable use of an elaborately designed spacetime model as the ``something fixed,'' i.e., absolute. This model must provide at least the following sequence of structures: point set, topological space, smooth manifold, geometric manifold, base for various bundles. The ``fine structure'' of spacetime inherent in this sequence is of course empirically unobservable directly, certainly when quantum mechanics is taken into account. This issue is at the basis of the difficulties in quantizing general relativity and has been approached in many different ways. Here we review an approach taking into account the non-Boolean properties of quantum logic when forming a spacetime model. Finally, we recall how the fundamental gauge of diffeomorphisms (the issue of general covariance vs coordinate conditions) raised deep conceptual problems for Einstein in his early development of general relativity. This is clearly illustrated in the notorious ``hole'' argument. This scenario, which does not seem to be widely known to practicing relativists, is nevertheless still interesting in terms of its impact for fundamental gauge issues.

Carl H. Brans

1998-01-09

380

Models for the volume of earliest Oligocene Antarctic ice on reconstructed Antarctic topography  

NASA Astrophysics Data System (ADS)

The Eocene-Oligocene (E-O) climate transition is widely recognized as including both growth of a substantial Antarctic ice sheet and cooling of the deep ocean, recorded most quantitatively by a sharp increase in benthic marine oxygen isotopes. As the oceanographic record of oxygen isotopes depends on both ice volume and temperature, substantial recent effort has been directed to interpreting proxy records of temperature and sea level in order to determine the changes in ice volume and temperature. The general consensus is that the ice-volume increase at E-O is comparable to or most plausibly larger than the volume of present Antarctic ice (25.4 M km3, BEDMAP). Early models of E-O ice growth have not produced this volume. One of the factors limiting the value of the early ice-growth models is the use of present Antarctic bedrock topography as a boundary condition. The use of present topography ignores the potentially significant long-term processes of landscape evolution including glacial erosion, thermal subsidence and tectonics which are likely to have changed the relationship between topography and ice dynamics in Antarctica. We present models contrasting the ice volume supported by the present topography (BEDMAP, restored for removing the load of modern ice) with the ice volume supported by minimum and maximum estimates of reconstructed E-O topography [Wilson, D.S., et al., Antarctic topography at the Eocene-Oligocene boundary, Palaeogeogr. Palaeoclimatol. Palaeoecol., 2011, in press, doi:10.1016/j.palaeo.2011.05.028], which restore substantial areas of West Antarctica above sea level. These models are based on running a 3-D ice-sheet model to equilibrium, in a climate obtained from a look-up matrix of GENESIS GCM snapshots with atmospheric CO2 set to 2x preindustrial level, and an average Earth orbit. Using a uniformly high-friction basal boundary condition for ice sliding, our preliminary predictions for total ice volume are 23.6 Mkm3 for BEDMAP, 35.6 Mkm3 for the reconstructed minimum, and 41.1 Mkm3 for the reconstructed maximum. Assuming the ?18O isotopic composition of early Oligocene ice was ~ -35%, these volumes would have increased deep-ocean-water ?18O by 0.58%, 0.87% and 1.01%, respectively. To account for the observed isotopic increase in benthic foraminifera of ~1.5% from the latest Eocene to the peak of Oi-1 (Oligocene isotope event 1), these values imply deep-ocean cooling of ~3.7°, 2.5° and 2.0° C, respectively. Cooling of 2.0-2.5° C is within the range of various proxy estimates.

Wilson, D. S.; Pollard, D.; DeConto, R.; Jamieson, S.; Luyendyk, B. P.

2011-12-01

381

TOPO-EUROPE: Studying Continental Topography and Deep Earth - Surface Processes in 4D  

NASA Astrophysics Data System (ADS)

Topography influences various aspects of society, not only in terms of the slow process of landscape evolution but also through climate (e.g. mountain building). Topographic evolution (changes in land, water and sea level) can seriously affect human life, as well as terrestrial geo-ecosystems. When fresh water or sea-water levels rise, or when land subsides, the risk of flooding increases. This directly affects local geo- ecosystems and human settlements. On the other hand, declining water levels and uplift may lead to a higher risk of erosion and even desertification. Similar examples could be given for groundwater, early life and climate change. Studying these aspects in an integrated way is essential to forward solid Earth Sciences in response to the needs of society (see http://www.yearofplanetearth.org/). To quantify topography evolution in space and time, understanding of the coupled deep Earth and surface processes is a requisite. The TOPO-EUROPE initiative of the International Lithophere Program (ILP) addresses the 4-D topography of the orogens and intra-plate regions of Europe through a multidisciplinary approach linking geology, geophysics, geodesy and geotechnology. TOPO-EUROPE integrates monitoring, imaging, reconstruction and modelling of the interplay between processes controlling continental topography and related natural hazards. Until now, research on neotectonics and related topography development of orogens and intra-plate regions has received little attention. TOPO-EUROPE initiates a number of novel studies on the quantification of rates of vertical motions, related tectonically controlled river evolution and land subsidence in carefully selected natural laboratories in Europe. From orogen through platform to continental margin, these natural laboratories include the Alps/Carpathians-Pannonian Basin System, the West and Central European Platform, the Apennines-Tyrrhenian-Maghrebian and the Aegean-Anatolian regions, the Iberian Peninsula and the Scandinavian Continental Margin. TOPO-EUROPE integrates European research facilities and know- how essential to advance the understanding of the role of topography in Earth System Dynamics. The principal objective of the network is twofold. Namely, to integrate national research programs into a common European network and, furthermore, to integrate activities among TOPO-EUROPE institutes and participants. Key objectives are to provide an interdisciplinary forum to share knowledge and information in the field of the neotectonic and topographic evolution of Europe, to promote and encourage multidisciplinary research on a truly European scale, to increase mobility of scientists and to train young scientists. An important step has been the selection in early 2008 by the European Science Foundation (ESF) of TOPO-EUROPE as one of its large scale European collaborative research initiatives (EUROCORES). In response to the ESF call for proposals, 42 outline proposals were submitted, resulting in 22 full proposals submitted for international peer-review. Out of these, ten collaborative research projects (CRP's) were selected for the ESF EUROCORES TOPO-EUROPE, with a total funding of 13 million Euro (M 18) and new research positions for more than 50 PhD students and post-doctoral researchers.

Cloetingh, S.; Topo-Europe Science Community, The

2009-04-01

382

Absolute and Convective Instability of a Liquid Jet  

NASA Technical Reports Server (NTRS)

The existence of absolute instability in a liquid jet has been predicted for some time. The disturbance grows in time and propagates both upstream and downstream in an absolutely unstable liquid jet. The image of absolute instability is captured in the NASA 2.2 sec drop tower and reported here. The transition from convective to absolute instability is observed experimentally. The experimental results are compared with the theoretical predictions on the transition Weber number as functions of the Reynolds number. The role of interfacial shear relative to all other relevant forces which cause the onset of jet breakup is explained.

Lin, S. P.; Hudman, M.; Chen, J. N.

1999-01-01

383

Balance of chemistry, topography, and mechanics at the cellbiomaterial interface: Issues and challenges for  

E-print Network

Balance of chemistry, topography, and mechanics at the cell­biomaterial interface: Issues of physicochemical cues: chemical, topographical, and mechanical. While sur- face chemistry and topography have been of creating surfaces with well-defined chemistry and topography combined with sensitive surface

384

Gaussian Power with Cylinder Vector Field Representation for Corneal Topography Maps Brian A. Barsky  

E-print Network

Gaussian Power with Cylinder Vector Field Representation for Corneal Topography Maps Brian A on commercially available corneal topography instru- ments are really one-dimensional, defining quantities only on the videokeratograph axis or on the location of asymmetries. We propose a new repre- sentation for corneal topography

California at Irvine, University of

385

On a correlation between the reciprocal of cometary semi-major axis and absolute brightness  

NASA Astrophysics Data System (ADS)

Data on observed comets have been studied in order to find out whether there exists a correlation between 1/a (where a is the semi-major radius) and H10 (the absolute magnitude). It is found that the increase in H10 from nearly parabolic orbits (D) to orbits of a period of 100 yr (B) is an average of 1.6, while the number of revolutions required for dynamical evolution from D to B orbits is about 700. The nuclear radius estimated from these data is consistent with Roemer's estimates of the nuclear radii of nearly parabolic comets. Thus, the process of dynamical diffusion is consistent with the observational results.

Yabushita, S.; Hasegawa, I.

1981-05-01

386

Ice sheet topography from retracked ERS-1 altimetry  

NASA Technical Reports Server (NTRS)

An objective of the ERS-1 radar altimeter is to measure the surface topography of the polar ice sheets to a precision on the order of a meter. ERS-1 Waveform Altimeter Product (WAP) data was corrected for several processing errors. A range correction from the WAP waveforms, using the multiparameter retracking algorithm to account for range tracking limitations inherent to radar altimetry, was derived. From crossover analysis, the resulting precision is shown to be about 2.1 m in ocean mode and 2.2 m in ice mode. A topography map, produced with 23 days of corrected data, shows details of the western part of west Antarctic ice sheet and part of the Ross ice shelf including ice divides, ice stream boundaries, and ice shelf grounding lines.

Zwally, H. Jay; Brenner, Anita C.; Dimarzio, John; Seiss, Timothy

1994-01-01

387

The long wavelength topography of Beethoven and Tolstoj basins, Mercury  

NASA Astrophysics Data System (ADS)

Topography derived from Mariner 10 stereo images is used to characterize the interior structure of two mercurian basins, Beethoven and Tolstoj. Beethoven and Tolstoj basins are shallow (~2.5 km and ~2 km deep, respectively) and relatively flat-floored. Beethoven basin has an interior topographic rise near the northwest margin. The topography of Beethoven and Tolstoj basins is similar to that of lunar mare-filled basins. Well-developed basin-concentric wrinkle ridges and arcuate graben associated with lunar mascons are absent in both Beethoven and Tolstoj basins. The lack of mascon tectonic features suggests that either 1) the mercurian basins have a relatively thin veneer of fill material, 2) Mercury's elastic lithosphere was too strong for significant lithospheric flexure and subsidence to occur, or 3) the basin fill material has little or no density contrast with the surrounding crust and thus exerts little net load on the mercurian lithosphere.

André, Sarah L.; Watters, Thomas R.; Robinson, Mark S.

2005-11-01

388

Irregular topography at the Earth's inner core boundary.  

PubMed

Compressional seismic wave reflected off the Earth's inner core boundary (ICB) from earthquakes occurring in the Banda Sea and recorded at the Hi-net stations in Japan exhibits significant variations in travel time (from -2 to 2.5 s) and amplitude (with a factor of more than 4) across the seismic array. Such variations indicate that Earth's ICB is irregular, with a combination of at least two scales of topography: a height variation of 14 km changing within a lateral distance of no more than 6 km, and a height variation of 4-8 km with a lateral length scale of 2-4 km. The characteristics of the ICB topography indicate that small-scale variations of temperature and/or core composition exist near the ICB, and/or the ICB topographic surface is being deformed by small-scale forces out of its thermocompositional equilibrium position and is metastable. PMID:22547788

Dai, Zhiyang; Wang, Wei; Wen, Lianxing

2012-05-15

389

Irregular topography at the Earth's inner core boundary  

PubMed Central

Compressional seismic wave reflected off the Earth’s inner core boundary (ICB) from earthquakes occurring in the Banda Sea and recorded at the Hi-net stations in Japan exhibits significant variations in travel time (from -2 to 2.5 s) and amplitude (with a factor of more than 4) across the seismic array. Such variations indicate that Earth’s ICB is irregular, with a combination of at least two scales of topography: a height variation of 14 km changing within a lateral distance of no more than 6 km, and a height variation of 4–8 km with a lateral length scale of 2–4 km. The characteristics of the ICB topography indicate that small-scale variations of temperature and/or core composition exist near the ICB, and/or the ICB topographic surface is being deformed by small-scale forces out of its thermocompositional equilibrium position and is metastable. PMID:22547788

Dai, Zhiyang; Wang, Wei; Wen, Lianxing

2012-01-01

390

Keratometry and corneal topography using multiple delay element OCT  

NASA Astrophysics Data System (ADS)

We have presented previously a novel method for the evaluation of the surface shape of an object, with immediate application to measurement of cornea shape. This method uses single shot C-scans obtained by using a multiple delay element (MDE) in the reference path of an OCT system. A calibrated MDE-OCT system can be used to measure the elevation of points on the cornea, in contrast to existing methods which are based on measurement of the cornea slope. The associated algorithm for extracting corneal topography data points from the MDE-OCT C-Scan image will be presented, data points which can then be used to calculate the Zernike coefficients for the cornea shape. The differences between the existing systems and the MDE-OCT method for keratometry and corneal topography are discussed.

Plesea, Lucian; Podoleanu, Adrian G.

2008-02-01

391

Synchronous interferometric demodulation of Placido mires applied to corneal topography  

E-print Network

This paper presents a novel digital interferometric method to demodulate Placido fringe patterns. This is a synchronous method which uses a computer-stored conic-wavefront as demodulating reference. Here we focuses on the experimental aspects to phase-demodulate Placido mires applied to corneal topography. This synchronous method is applied to two topographic Placido images and their de-modulated corneal-slope deformation is estimated. This conic-interferometric method is highly robust against typical "noisy" signals in Placido topography such as: reflected eyelashes and iris structures. That is because the eyelashes and the iris structure are high frequency "noisy" signals corrupting the reflected Placido mire, so they are filtered-out by this method. Digital synchronous interferometry is here applied for the first time to demodulate corneal topographic concentric-rings images (Patent pending at the USPTO).

Servin, Manuel

2012-01-01

392

Sound propagation over uneven ground and irregular topography  

NASA Technical Reports Server (NTRS)

The goal of this research is to develop theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere. Irregular topography here is understood to imply a ground surface that is not idealizable as being perfectly flat or that is not idealizable as having a constant specific acoustic impedance. The interest of this study focuses on circumstances where the propagation is similar to what might be expected for noise from low-attitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence. The activities and developments that have resulted during the period, August 1986 through February 1987, are discussed.

Berthelot, Yves H.; Kearns, James A.; Pierce, Allan D.; Main, Geoffrey L.

1987-01-01

393

Topography and refractometry of nanostructures using spatial light interference microscopy.  

PubMed

Spatial light interference microscopy (SLIM) is a novel method developed in our laboratory that provides quantitative phase images of transparent structures with a 0.3 nm spatial and 0.03 nm temporal accuracy owing to the white light illumination and its common path interferometric geometry. We exploit these features and demonstrate SLIM's ability to perform topography at a single atomic layer in graphene. Further, using a decoupling procedure that we developed for cylindrical structures, we extract the axially averaged refractive index of semiconductor nanotubes and a neurite of a live hippocampal neuron in culture. We believe that this study will set the basis for novel high-throughput topography and refractometry of man-made and biological nanostructures. PMID:20081970

Wang, Zhuo; Chun, Ik Su; Li, Xiuling; Ong, Zhun-Yong; Pop, Eric; Millet, Larry; Gillette, Martha; Popescu, Gabriel

2010-01-15

394

Evaluation of Esophageal Contractile Propagation using Esophageal Pressure Topography  

PubMed Central

Background High-resolution manometry and esophageal pressure topography have ienhanced our ability to analyze esophageal motor disturbances by improving the detail and accuracy of measurements of peristaltic activity. This has been extremely helpful in the evaluation of disorders of rapid propagation as the technique is able to define important time points and physiologic landmarks that are crucial in defining peristaltic velocity and latency intervals. Purpose The goal of the current review will be to assess how esophageal pressure topography has impacted our ability to define important phenotypes of rapid propagation. Additionally, this review will also be utilized to complement the description of the Chicago Classification of Esophageal Motor Disorders, which is presented in this supplement issue. PMID:22248104

Pandolfino, J.E.; Sifrim, D.

2013-01-01

395

Fracture surface topography analysis of in-beam fatigue behavior for 20% cold-worked 316 stainless steel  

NASA Astrophysics Data System (ADS)

Topography on the fatigue fracture surface was examined by using a confocal laser microscope for the side-notched small specimens of 20% cold-worked 316 stainless steel fractured in stress-controlled fatigue tests under the in-beam (dynamic), post-irradiation (static) and unirradiation conditions with 17 MeV protons at 60 °C. A technique of the fracture surface topography analysis (FRASTA) was adopted to extract the information of plastic deformation at the crack tip for the in-beam, post-irradiation and unirradiated specimens. The progress in plastic deformation at the crack tip was significantly delayed in the dynamic irradiation condition while not so much as in the static irradiation condition. The present results of FRASTA would not only support the superiority of dynamic irradiation effect to the static irradiation effect on fatigue behavior but also provide good evidence for the mechanism of the dynamic irradiation effect based on the interaction between continuously induced defect clusters and mobile dislocations.

Murase, Y.; Nagakawa, Johsei; Yamamoto, N.

2003-11-01

396

Three-dimensional modeling and numerical simulations of avalanches over a real mountain topography  

NASA Astrophysics Data System (ADS)

For real three-dimensional numerical simulations of avalanches over mountain topography, we have developed a new preprocessor that generates the mesh and sets the initial conditions. In our approach, first we select the region of interest on which the preprocessor creates a colored overlay with possible starting positions, then we choose the initial sliding zone. Afterwards, the preprocessor creates an unstructured triangulated surface. Together with an initial hexahedral mesh, the utility, called the snappyHexMesh in the OpenFOAM software package [1], creates the final mesh. Our second reprocessing utility sets the initial conditions needed by the numerical solver for the avalanche flow simulation. In the next step, we calculate the flow dynamics with our numerical solver, which is based on interFoam [1]. Different rheological models and parameters can be chosen in this solver. We implement, for the first time, the Coulomb-type internal friction rheology with a Coulomb sliding law at the base in connection to the continuum dynamical model equations for the mass and momentum balances. We show good comparisons between our numerical solutions and published results of small scale laboratory experiments. We also present some preliminary results for avalanche flows down real mountain slopes. When calibrated with field measurements, our numerical simulations (based on the full three-dimensional flow dynamics) can provide a deeper understanding of the dynamics of real avalanches, with applications to proper hazard mapping and improved risk management. [1] http://www.openfoam.org/

Kröner, C.; Pudasaini, S. P.

2012-04-01

397

Orion Absolute Navigation System Progress and Challenge  

NASA Technical Reports Server (NTRS)

The absolute navigation design of NASA's Orion vehicle is described. It has undergone several iterations and modifications since its inception, and continues as a work-in-progress. This paper seeks to benchmark the current state of the design and some of the rationale and analysis behind it. There are specific challenges to address when preparing a timely and effective design for the Exploration Flight Test (EFT-1), while still looking ahead and providing software extensibility for future exploration missions. The primary onboard measurements in a Near-Earth or Mid-Earth environment consist of GPS pseudo-range and delta-range, but for future explorations missions the use of star-tracker and optical navigation sources need to be considered. Discussions are presented for state size and composition, processing techniques, and consider states. A presentation is given for the processing technique using the computationally stable and robust UDU formulation with an Agee-Turner Rank-One update. This allows for computational savings when dealing with many parameters which are modeled as slowly varying Gauss-Markov processes. Preliminary analysis shows up to a 50% reduction in computation versus a more traditional formulation. Several state elements are discussed and evaluated, including position, velocity, attitude, clock bias/drift, and GPS measurement biases in addition to bias, scale factor, misalignment, and non-orthogonalities of the accelerometers and gyroscopes. Another consideration is the initialization of the EKF in various scenarios. Scenarios such as single-event upset, ground command, and cold start are discussed as are strategies for whole and partial state updates as well as covariance considerations. Strategies are given for dealing with latent measurements and high-rate propagation using multi-rate architecture. The details of the rate groups and the data ow between the elements is discussed and evaluated.

Holt, Greg N.; D'Souza, Christopher

2012-01-01

398

Absolute determination of local tropospheric OH concentrations  

NASA Technical Reports Server (NTRS)

Long path absorption (LPA) according to Lambert Beer's law is a method to determine absolute concentrations of trace gases such as tropospheric OH. We have developed a LPA instrument which is based on a rapid tuning of the light source which is a frequency doubled dye laser. The laser is tuned across two or three OH absorption features around 308 nm with a scanning speed of 0.07 cm(exp -1)/microsecond and a repetition rate of 1.3 kHz. This high scanning speed greatly reduces the fluctuation of the light intensity caused by the atmosphere. To obtain the required high sensitivity the laser output power is additionally made constant and stabilized by an electro-optical modulator. The present sensitivity is of the order of a few times 10(exp 5) OH per cm(exp 3) for an acquisition time of a minute and an absorption path length of only 1200 meters so that a folding of the optical path in a multireflection cell was possible leading to a lateral dimension of the cell of a few meters. This allows local measurements to be made. Tropospheric measurements have been carried out in 1991 resulting in the determination of OH diurnal variation at specific days in late summer. Comparison with model calculations have been made. Interferences are mainly due to SO2 absorption. The problem of OH self generation in the multireflection cell is of minor extent. This could be shown by using different experimental methods. The minimum-maximum signal to noise ratio is about 8 x 10(exp -4) for a single scan. Due to the small size of the absorption cell the realization of an open air laboratory is possible in which by use of an additional UV light source or by additional fluxes of trace gases the chemistry can be changed under controlled conditions allowing kinetic studies of tropospheric photochemistry to be made in open air.

Armerding, Wolfgang; Comes, Franz-Josef

1994-01-01

399

An Absolute Radius Scale for Saturn's Rings from Cassini Occultations  

NASA Astrophysics Data System (ADS)

Abstract (2,250 Maximum Characters): The Cassini mission has provided a remarkable opportunity to investigate the structure and dynamics of the Saturn ring system at the sub-km radial scale, using hundreds of individual stellar and radio occultations from the UVIS, VIMS, and RSS instruments. From precise measurements of ring and gap edges, we have been able to determine the orbital characteristics of over one hundred features in the rings. A crucial step in the orbital determination is the establishment of a highly accurate radius scale for the rings. This is compounded by uncertainties in the positions of the occulted stars, km-scale trajectory errors in the spacecraft location, and inexact knowledge of the direction and precession rate of Saturn’s pole. We have taken an iterative approach in which we identify a set of 30 or so putative circular, equatorial features, solve for along-track trajectory errors for each occultation, and use this best-fitting orbital solution to establish the reference system for determination of the orbits of non-circular ring features. Using thousands of individual measurements of rings in the Cassini data, we have determined an absolute radius scale for each contributing occultation with an accuracy of about 200 m for the C and B rings and the Cassini Division. This enables us to detect and measure very small dynamical effects such as weak normal modes in ring edges, and to determine the phases of density waves, including very short wavelength outer Lindblad resonances in the C ring, as reported at this meeting. We calculate the sensitivity of the radius scale to the assumed pole direction and precession rate. Ultimately, we will combine these results with Voyager, HST, and pre-Cassini Earth-based occultation measurements to refine our knowledge of Saturn’s pole direction and precession.

McGhee, Colleen; French, R. G.; Jacobson, R. A.; Nicholson, P. D.; Colwell, J. E.; Marouf, E. A.; Lonergan, K.; Sepersky, T.

2013-05-01

400

Printability of topography in alternating aperture phase-shift masks  

Microsoft Academic Search

Alternating aperture phase-shift mask (AAPSM) technology in combination with conventional illumination enables the imaging needed in the 65nm node and beyond, thanks to its high image contrast and small mask error factor (MEF). It is a known point of attention that AAPSM topography induces an image intensity imbalance between the light propagating through the zero and pi-shifted space. There are

Vicky Philipsen; Rik Jonckheere

2004-01-01

401

Correcting for surface topography in X-ray fluorescence imaging.  

PubMed

Samples with non-planar surfaces present challenges for X-ray fluorescence imaging analysis. Here, approximations are derived to describe the modulation of fluorescence signals by surface angles and topography, and suggestions are made for reducing this effect. A correction procedure is developed that is effective for trace element analysis of samples having a uniform matrix, and requires only a fluorescence map from a single detector. This procedure is applied to fluorescence maps from an incised gypsum tablet. PMID:25343805

Geil, E C; Thorne, R E

2014-11-01

402

Stroboscopic X-ray topography of quartz resonators  

Microsoft Academic Search

Stroboscopic X-ray topography of 1-ns time resolution with synchrotron radiation has been used to study the vibrations in quartz resonators. Time-resolved images of the vibration reveal the existence of particular modes which cannot be observed on time-integrated images by conventional methods. A theoretical calculation is carried out to characterize pendellosung fringes on stroboscopic X-ray section topographs in weakly vibrating crystals.

A. Zarka; B. Capelle; Y. Zheng; J. Detaint; J. Schwartzel

1988-01-01

403

Mode shape analysis techniques using synchrotron X-ray topography  

Microsoft Academic Search

X-ray topography using synchrotron radiation is used to investigate vibrational states in quartz resonators. After a brief review of different methods and possibilities obtained with synchrotron radiation, some observations on vibration modes, especially on coupled piezo-electric components in quartz AT and BT resonators, are reported. The results from experiments reveal time-progressive components and several complex coupled components in AT and

B. Capelle; J. Detaint; A. Zarka; Y. Zheng; J. Schwartzel

1990-01-01

404

Some Bristol–Prague explorations in x-ray topography  

Microsoft Academic Search

This paper briefly chronicles a long-standing and productive collaboration between the Institute of Physics, Czech Academy of Science and the H H Wills Physics Laboratory. It began in early 1962 with a brief visit to Bristol by Milena Polcarov. The initial aim, successfully achieved, was the mapping by transmission topography of dislocations in melt-grown single crystals of a Fe–Si alloy.

A R Lang

2005-01-01

405

X-ray topography analysis of bulk acoustic wave resonators  

Microsoft Academic Search

X-ray topography is first used to totally examine the fundamental modes of acoustic oscillations in the bulk-acoustic-wave\\u000a (BAW) resonator on the base of an AT-cut quartz crystal at the first and third harmonics. As is evident from the experiments,\\u000a the anharmonic longitudinal oscillations of the resonator can be visualized, just as the fundamental transverse acoustic oscillations\\u000a can be. The amplitude-frequency

D. V. Irzhak; D. V. Roshchupkin; D. V. Punegov; S. A. Sakharov

2007-01-01

406

X-ray diffraction topography image materials by molecular probe  

Microsoft Academic Search

Crystallinity, composition, homogeneity and anisotropy determine the mechanical properties of materials significantly, but the performance of most non-destructive techniques is too poor for measuring these micro structures as they are optimized for finding individual flaws\\/defects. X-ray (wide angle) Diffraction Topography by single beam scanning images molecular information at a spatial resolution of several ten micrometers even in three dimensions. Especially

Manfred P. Hentschel; Axel Lange; Joerg Schors; Oliver Wald

2005-01-01

407

X-ray topography study of complex silicon microcircuits  

Microsoft Academic Search

The correlation between the yield of silicon microcircuits wafers versus defects observed in X-ray topographs produced by a high speed curved wafer X-ray topographic camera was investigated. Most of the topographs were made after final wafer probe. Results indicated that most high volume silicon wafer processing does not need X-ray topography as a routine process control. It is further indicated

D. L. Parker

1981-01-01

408

Research of the Method of Local Topography Rapid Reconstructed  

Microsoft Academic Search

\\u000a For fast and convenient access to the environment based on the geomorphic characteristics of camouflage regional model for\\u000a the complexity of topography, this article analyzes a variety of terrain modeling method’s advantages and limitations, discussed\\u000a a variety of modeling methods in the set up of the study of basic on the hybrid modeling method and the integrated use of\\u000a research

Minrong Zhao; Shengli Deng; Ze Shi

2009-01-01

409

Intraocular lens power calculations using corneal topography after photorefractive keratectomy  

Microsoft Academic Search

PURPOSE: To report two patients (two eyes) with previous photorefractive keratectomy, who subsequently underwent cataract extraction years later.DESIGN: Case reports.METHODS: Corneal topography was used to determine corneal power used in intraocular lens power calculations.RESULTS: In two eyes of two patients, intraocular lens calculations after photorefractive keratectomy were inadequate, which resulted in a hyperopic postoperative refractive error requiring implantation of a

John G Ladas; Brian S Boxer Wachler; John D Hunkeler; Daniel S Durrie

2001-01-01

410

On fractional Bessel equation and the description of corneal topography  

E-print Network

In this note we apply a modified fractional Bessel differential equation to the problem of describing corneal topography. We find the solution in terms of the power series. This solution has an interesting behavior at infinity which is a generalization of the classical results for modified Bessel function of order 0. Our model fits the real corneal geometry data with an error of order of a few per cent.

Okrasi?ski, Wojciech

2012-01-01

411

Electronic cigarettes: abuse liability, topography and subjective effects  

PubMed Central

Objective To review the available evidence evaluating the abuse liability, topography, subjective effects, craving and withdrawal suppression associated with e-cigarette use in order to identify information gaps and provide recommendations for future research. Methods Literature searches were conducted between October 2012 and January 2014 using five electronic databases. Studies were included in this review if they were peer-reviewed scientific journal articles evaluating clinical laboratory studies, national surveys or content analyses. Results A total of 15 peer-reviewed articles regarding behavioural use and effects of e-cigarettes published between 2010 and 2014 were included in this review. Abuse liability studies are limited in their generalisability. Topography (consumption behaviour) studies found that, compared with traditional cigarettes, e-cigarette average puff duration was significantly longer, and e-cigarette use required stronger suction. Data on e-cigarette subjective effects (such as anxiety, restlessness, concentration, alertness and satisfaction) and withdrawal suppression are limited and inconsistent. In general, study data should be interpreted with caution, given limitations associated with comparisons of novel and usual products, as well as the possible effects associated with subjects’ previous experience/inexperience with e-cigarettes. Conclusions Currently, very limited information is available on abuse liability, topography and subjective effects of e-cigarettes. Opportunities to examine extended e-cigarette use in a variety of settings with experienced e-cigarette users would help to more fully assess topography as well as behavioural and subjective outcomes. In addition, assessment of ‘real-world’ use, including amount and timing of use and responses to use, would clarify behavioural profiles and potential adverse health effects. PMID:24732159

Evans, Sarah E; Hoffman, Allison C

2014-01-01

412

Core-mantle boundary topography and whole-mantle convection  

NASA Astrophysics Data System (ADS)

The seismically observed topography of the core-mantle boundary (CMB) and the velocities of the surface tectonic plates together provide important observational constraints on viscous flow models of the earth's mantle. It is shown here that the CMB deflections inferred by Morelli and Dziewonski (1987) may be explained in terms of a simple model of whole-mantle convection. A new method for inferring the penetration depths of subducted slabs is presented.

Forte, Alessandro; Peltier, W. Richard

1989-07-01

413

Bridges of the sella turcica - anatomy and topography.  

PubMed

This paper presents anatomy and topography of the inconstant osseous bridges that may occur in the sella turcica region. The interclinoid bridge and the caroticoclinoid bridge can be formed in consequence of abnormal ossification of the dural folds or disturbances in development of the sphenoid bone. Their presence may be of clinical importance because of potential influence on the neurovascular structures passing in the vicinity of the clinoid processes of the sphenoid bone. PMID:24852690

Skrzat, Janusz; Mroz, Izabela; Marchewka, Justyna

2012-01-01

414

Topography of the Northern Hemisphere of Mercury from MESSENGER Laser Altimetry  

NASA Technical Reports Server (NTRS)

Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury s topography occurred after the earliest phases of the planet s geological history.

Zuber,Maria T.; Smith, David E.; Phillips, Roger J.; Solomon, Sean C.; Neumann, Gregory A.; Hauck, Steven A., Jr.; Peale, Stanton J.; Barnouin, Oliver S.; Head, James W.; Johnson, Catherine L.; Lemoine, Frank G.; Mazarico, Erwan; Sun, Xiaoli; Torrence, Mark H.; Freed, Andrew M.; Klimczak, Christian; Margot, Jean-Luc; Oberst, Juergen; Perry, Mark E.; McNutt, Ralph L., Jr.; Balcerski, Jeffrey A.; Michel, Nathalie; Talpe, Matthieu J.; Yang, Di

2012-01-01

415

Topography of the northern hemisphere of Mercury from MESSENGER laser altimetry.  

PubMed

Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history. PMID:22438510

Zuber, Maria T; Smith, David E; Phillips, Roger J; Solomon, Sean C; Neumann, Gregory A; Hauck, Steven A; Peale, Stanton J; Barnouin, Olivier S; Head, James W; Johnson, Catherine L; Lemoine, Frank G; Mazarico, Erwan; Sun, Xiaoli; Torrence, Mark H; Freed, Andrew M; Klimczak, Christian; Margot, Jean-Luc; Oberst, Jürgen; Perry, Mark E; McNutt, Ralph L; Balcerski, Jeffrey A; Michel, Nathalie; Talpe, Matthieu J; Yang, Di

2012-04-13

416

Anomalous topography on the continental shelf around Hudson Canyon  

USGS Publications Warehouse

Recent seismic-reflection data show that the topography on the Continental Shelf around Hudson Canyon is composed of a series of depressions having variable spacings (< 100 m to 2 km), depths (1-10 m), outlines, and bottom configurations that give the sea floor an anomalous "jagged" appearance in profile. The acoustic and sedimentary characteristics, the proximity to relict shores, and the areal distribution indicate that this rough topography is an erosional surface formed on Upper Pleistocene silty sands about 13,000 to 15,000 years ago by processes related to Hudson Canyon. The pronounced southward extension of the surface, in particular, may reflect a former increase in the longshore-current erosion capacity caused by the loss of sediments over the canyon. Modern erosion or nondeposition of sediments has prevented the ubiquitous sand sheet on the Middle Atlantic shelf from covering the surface. The "anomalous" topography may, in fact, be characteristic of areas near other submarine canyons that interrupt or have interrupted the longshore drift of sediments. ?? 1979.

Knebel, H. J.

1979-01-01

417

A Simple Laboratory Experiment for the Determination of Absolute Zero  

Microsoft Academic Search

A novel method that evaluates absolute zero was developed. It employs a remarkably simple and inexpensive apparatus and is based on the extrapolation of the volume of a given amount of dry air to zero volume after a volume of air trapped inside a 10-mL graduated cylinder is measured at various temperatures. This method of determining absolute zero is new

Michelle Song Kim; Suw-Young Ly

2001-01-01

418

Determination of Absolute Zero Using a Computer-Based Laboratory  

ERIC Educational Resources Information Center

We present a simple computer-based laboratory experiment for evaluating absolute zero in degrees Celsius, which can be performed in college and undergraduate physical sciences laboratory courses. With a computer, absolute zero apparatus can help demonstrators or students to observe the relationship between temperature and pressure and use…

Amrani, D.

2007-01-01

419

A vertically integrated media-isolated absolute pressure sensor  

Microsoft Academic Search

A novel, media-isolated, temperature-compensated, bulk-micromachined integrated absolute pressure sensor has successfully been developed. The sensor is usable for most applications involving exposure to harsh media, such as fuel vapor seen by manifold absolute pressure (MAP) sensors. Characterization of the device indicates that the devices fabricated meet specifications of a MAP sensor

Ken Goldman; George Gritt; Ira Baskett; K. Sooriakumar; Dan Wallace; Don Hughes; Mahesh Shah

1997-01-01

420

Automated guided vehicle with absolute encoded guide-path  

Microsoft Academic Search

An automated guided vehicle (AGV) having the ability to recover its absolute position anywhere on the guide-path is described. It uses an original guide-path encoding technique, based on the properties of pseudorandom binary sequences, resulting in a minimum code complexity of 1 bit per quantization step. An experimental AGV system was built to test the proposed absolute position measurement method

E. M. Petriu

1991-01-01

421

Absolute Model of Autonomy and Power: Toward Group Effects  

E-print Network

of Autonomy We consider an agent reacting in a rapidly changing environment and thereby consider it situated is a distinguished entity that might judge or change an agent's autonomy. This is studied under adjustable autonomy We present a model of absolute autonomy and power in agent systems. This absolute sense of autonomy

Hexmoor, Henry

422

Influence of planetary-scale topography on the diurnal thermal tide during the 1971 Martian dust storm  

NASA Technical Reports Server (NTRS)

Data obtained with the Mariner 9 infrared spectroscopy experiment during the Martian dust storm of 1971-72 are examined for evidence of topographic influence on the atmospheric thermal structure. Temperature perturbations which are well correlated with the planetary-scale topography are found superposed on the large-amplitude diurnal thermal tide previously reported. Applications of tidal theory to the data indicate that the observed perturbations result from the kinematic interaction of the westward traveling diurnal wave with the large-scale components of topography. The dominant mode is excited by the wavenumber 2 topography component and is a vertically evanescent, eastward traveling wave with an equivalent depth comparable to the atmospheric-scale height. The principle dynamic effect of this mode is the enhancement of the amplitude of the near-surface diurnal wind to over 40 m/s in limited areas near 30 deg S latitude. Thus, it appears likely that dust was injected into the atmosphere in these regions during the storm. Other waves excited include vertically propagating modes which produce little effect in the lower atmosphere, but may represent a source of energy for the upper atmosphere during dust storm conditions.

Conrath, B. J.

1976-01-01

423

Geophysics of Titan from gravity, topography and spin state  

NASA Astrophysics Data System (ADS)

For the terrestrial planets, combined analyses of gravity and topography have greatly improved our understanding of these bodies' interiors [1]. The spin state and orientation of a planetary body can also be diagnostic of its internal structure [2]. Recently acqu