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Sample records for topography gmrt synthesis

  1. Accessing the Global Multi-Resolution Topography (GMRT) Synthesis through Gmrt Maptool

    NASA Astrophysics Data System (ADS)

    Ferrini, V. L.; Morton, J. J.; Barg, B.; Carbotte, S. M.

    2014-12-01

    The Global Multi-Resolution Topography (GMRT) Synthesis (http://gmrt.marine-geo.org) is a dynamically maintained global multi-resolution synthesis of terrestrial and seafloor elevation data maintained as both images and gridded data values as part of the IEDA Marine Geoscience Data System. GMRT seamlessly brings together a variety of elevation sources, and includes ship-based multibeam sonar collected throughout the global oceans that is processed by the GMRT Team and is gridded to 100-m resolution. New versions of GMRT are released twice each year, typically adding processed multibeam data from ~80 cruises per year. GMRT grids and images can be accessed through a variety of tools and interfaces including GeoMapApp (http://www.geomapapp.org) the GMRT MapTool (http://www.marine-geo.org/tools/maps_grids.php), and images can also be accessed through a Web Map Service. We have recently launched a new version of our web-based GMRT MapTool interface, which provides custom access to the gridded data values in standard formats including GeoTIFF, ArcASCII and GMT NetCDF. Several resolution options are provided for these gridded data, and corresponding images can also be generated. Coupled with this new interface is an XML metadata service that provides attribution information and detailed metadata about source data components (cruise metadata, sensor metadata, and full list of source data files) for any region of interest. Metadata from the attribution service is returned to the user along with the requested data, and is also combined with the data itself in new Bathymetry Attributed Grid (BAG) formatted files.

  2. The Global Multi-Resolution Topography (GMRT) Synthesis

    NASA Astrophysics Data System (ADS)

    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

    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).

  3. A real-time software backend for the GMRT

    NASA Astrophysics Data System (ADS)

    Roy, Jayanta; Gupta, Yashwant; Pen, Ue-Li; Peterson, Jeffrey B.; Kudale, Sanjay; Kodilkar, Jitendra

    2010-08-01

    The new era of software signal processing has a large impact on radio astronomy instrumentation. Our design and implementation of a 32 antennae, 33 MHz, dual polarization, fully real-time software backend for the GMRT, using only off-the-shelf components, is an example of this. We have built a correlator and a beamformer, using PCI-based ADC cards and a Linux cluster of 48 nodes with dual gigabit inter-node connectivity for real-time data transfer requirements. The highly optimized compute pipeline uses cache efficient, multi-threaded parallel code, with the aid of vectorized processing. This backend allows flexibility in final time and frequency resolutions, and the ability to implement algorithms for radio frequency interference rejection. Our approach has allowed relatively rapid development of a fairly sophisticated and flexible backend receiver system for the GMRT, which will greatly enhance the productivity of the telescope. In this paper we describe some of the first lights using this software processing pipeline. We believe this is the first instance of such a real-time observatory backend for an intermediate sized array like the GMRT.

  4. Rate and topography of cell wall synthesis during the division cycle of Salmonella typhimurium.

    PubMed Central

    Cooper, S

    1988-01-01

    The rates of synthesis of peptidoglycan and protein during the division cycle of Salmonella typhimurium have been measured by using the membrane elution technique and differentially labeled diaminopimelic acid and leucine. The cells were labeled during unperturbed exponential growth and then bound to a nitrocellulose membrane by filtration. Newborn cells were eluted from the membrane with fresh medium. The radioactivity in the newborn cells in successive fractions was determined. As the cells are eluted from the membrane as a function of their cell cycle age at the time of labeling, the rate of incorporation of the different radioactive compounds as a function of cell cycle age can be determined. During the first part of the division cycle, the ratio of the rates of protein and peptidoglycan synthesis was constant. During the latter part of the division cycle, there was an increase in the rate of peptidoglycan synthesis relative to the rate of protein synthesis. These results support a simple, bipartite model of cell surface increase in rod-shaped cells. Before the start of constriction, the cell surface increased only by cylindrical extension. After cell constriction started, the cell surface increased by both cylinder and pole growth. The increase in surface area was partitioned between the cylinder and the pole so that the volume of the cell increased exponentially. No variation in cell density occurred because the increase in surface allowed a continuous exponential increase in cell volume that accommodated the exponential increase in cell mass. Protein was synthesized exponentially during the division cycle. The rate of cell surface increase was described by a complex equation which is neither linear nor exponential. PMID:3275624

  5. Results from GMRT 150 MHz Radio Observations: Search for Steep Spectrum Radio Sources

    NASA Astrophysics Data System (ADS)

    Ishwara-Chandra, C. H.; Marathe, R.

    2007-12-01

    We present results from deep 150 MHz low frequency radio observations with Giant Meterwave Radio Telescope (GMRT), India. GMRT consists of 30 antennas, each of 45 meter diameter operating at frequencies from 150 MHz to 1400 MHz. At 150 MHz, GMRT can image the sky with high resolution ( 20 arcsec) of area of 10 square degrees with single pointing, which allows to detect a few hundred radio sources down to 10 mJy. We have carried out deep imaging at 150 MHz of two fields; one surrounding Upsilon Andromeda and another encompassing the cluster Abell 764. The rms noise achieved is 2 mJy/beam. The resolution in both images were 20 arcsec. The radio spectral index analysis of the sources in the field using the higher frequency NVSS (1400 MHz) flux densities with GMRT flux densities at 150 MHz helps us to detect sources with extreme spectral indices. Because the majority of high redshift radio sources tend to exhibit steeper radio spectra, deep imaging of the fields with GMRT at 150 MHz will help to detect/discover high redshift radio sources. Our analysis shows that 8% of the sources detected at 150 MHz have very steep spectra with the spectral index exceeding 1.25 (S_? ? ?-?).

  6. Rate and topography of peptidoglycan synthesis during cell division in Escherichia coli: Concept of a leading edge

    SciTech Connect

    Wientjes, F.B.; Nanninga, N. )

    1989-06-01

    The rate at which the peptidoglycan of Escherichia coli is synthesized during the division cycle was studied with two methods. One method involved synchronization of E. coli MC4100 lysA cultures by centrifugal elutriation and subsequent pulse-labeling of the synchronously growing cultures with (meso-{sup 3}H)diaminopimelic acid (({sup 3}H)Dap). The second method was autoradiography of cells pulse-labeled with ({sup 3}H)Dap. It was found that the peptidoglycan is synthesized at a more or less exponentially increasing rate during the division cycle with a slight acceleration in this rate as the cells start to constrict. Apparently, polar cap formation requires synthesis of extra surface components, presumably to accommodate for a change in the surface-to-volume ratio. Furthermore, it was found that the pool size of Dap was constant during the division cycle. Close analysis of the topography of ({sup 3}H)Dap incorporation at the constriction site revealed that constriction proceeded by synthesis of peptidoglycan at the leading edge of the invaginating cell envelope. During constriction, no reallocation of incorporation occurred, i.e., the incorporation at the leading edge remained high throughout the process of constriction. Impairment of penicillin-binding protein 3 by mutation or by the specific {beta}-lactam antibiotic furazlocillin did not affect ({sup 3}H)Dap incorporation during initiation of constriction. However, the incorporation at the constriction site was inhibited in later stages of the constriction process. It is concluded that during division at least two peptidoglycan-synthesizing systems are operating sequentially.

  7. VizieR Online Data Catalog: GMRT Radio Halo Cluster Survey diffuse sources (Venturi+, 2013)

    NASA Astrophysics Data System (ADS)

    Venturi, T.; Giacintucci, S.; Dallacasa, D.; Cassano, R.; Brunetti, G.; Macario, G.; Athreya, R.

    2012-11-01

    High sensitivity imaging was performed using the GMRT at 325MHz and 240MHz. The properties of the diffuse emission in each cluster were compared to our 610MHz images and/or literature information available at other frequencies, in order to derive the integrated spectra over a wide frequency range. (5 data files).

  8. GMRT Low frequency radio observation of Cyg X-3 at the time of flare

    NASA Astrophysics Data System (ADS)

    Pal, Sabyasachi; Rao, A. Pramesh

    2007-06-01

    Trushkin et al. (#Atel 1092) detected beginning of a new flaring activity in galactic black hole candidate Cygnus X-3. We have observed the source from UT 2.99 June to 3.08 June, 2007 in 243 and 614 MHz frequencies using Giant Meterwave Radio Telescope (GMRT). The source was variable and seemed to rise during our observation.

  9. Search for Radio Emission from Extrasolar Planets: Preliminary Analysis of GMRT Data

    NASA Astrophysics Data System (ADS)

    Majid, W. A.; Chandra, I.; Kuiper, T.; Lazio, J.; Winterhalter, D.; Naudet, C.; Treumann, R.; Zarka, P.

    2005-05-01

    In 2004 we carried out a series of short calibration runs using the central square array of the GMRT. At the operating RF of 150 MHz, we have determined that the GMRT has a fantastic sensitivity of 2 mJy over a bandwidth of 5 MHz and a timescale of one hour and is relatively free of RFI between midnight and early morning hours local time. As part of the calibration runs, we have carried out brief observation of UpsAnd with various observing strategies. In early 2005, we were granted observing time on the GMRT during its Cycle 7 observation period. Our focus to date has been in characterizing the large scale structure of the dynamic spectra, identifying RFI and developing filters to remove them. We will present our results from both the short calibrations runs of 2004 as well as those obtained from the 2005 observations. We will also describe techniques for detection of chirps as present in Jupiter observations, including match filter strategies. In addition we will describe some preliminary results for detecting bursts via statistical techniques. We plan to use Jupiter and Saturn data to calibrate our detection efficiency for various strategies. We will also discuss our software package for data analysis and computing strategies that we have adopted on our Beowulf Linux cluster at JPL.

  10. Facile synthesis of hydrangea flower-like hierarchical gold nanostructures with tunable surface topographies for single-particle surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Song, C. Y.; Zhou, N.; Yang, B. Y.; Yang, Y. J.; Wang, L. H.

    2015-10-01

    The physicochemical properties of noble metal nanocrystals depend strongly on their size and shape, and it is becoming clear that the design and facile synthesis of particular nanostructures with tailored shape and size is especially important. Herein a novel class of hydrangea flower-like hierarchical gold nanostructures with tunable surface topographies and optical properties are prepared for the first time by a facile, one-pot, seedless synthesis using ascorbic acid (AA) to reduce hydrogen tetrachloroaurate (HAuCl4) in the presence of (1-hexadecyl)trimethylammonium chloride (CTAC). The morphologies of the synthesized gold nanoflowers are controlled and fine-tuned by varying the synthetic conditions such as the concentration of reagents and the growth temperature. Due to their unique hierarchical three-dimensional (3D) structures with rich hot spots, these gold nanoflowers exhibit an efficient performance in single-particle surface-enhanced Raman scattering (SERS). The work stands out as an interesting approach for anisotropic particle synthesis and morphological control, and the proposed novel, hierarchical gold nanoflowers have a number of exciting potential applications in SERS-based sensors.The physicochemical properties of noble metal nanocrystals depend strongly on their size and shape, and it is becoming clear that the design and facile synthesis of particular nanostructures with tailored shape and size is especially important. Herein a novel class of hydrangea flower-like hierarchical gold nanostructures with tunable surface topographies and optical properties are prepared for the first time by a facile, one-pot, seedless synthesis using ascorbic acid (AA) to reduce hydrogen tetrachloroaurate (HAuCl4) in the presence of (1-hexadecyl)trimethylammonium chloride (CTAC). The morphologies of the synthesized gold nanoflowers are controlled and fine-tuned by varying the synthetic conditions such as the concentration of reagents and the growth temperature. Due to their unique hierarchical three-dimensional (3D) structures with rich hot spots, these gold nanoflowers exhibit an efficient performance in single-particle surface-enhanced Raman scattering (SERS). The work stands out as an interesting approach for anisotropic particle synthesis and morphological control, and the proposed novel, hierarchical gold nanoflowers have a number of exciting potential applications in SERS-based sensors. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr04827c

  11. Facile synthesis of hydrangea flower-like hierarchical gold nanostructures with tunable surface topographies for single-particle surface-enhanced Raman scattering.

    PubMed

    Song, C Y; Zhou, N; Yang, B Y; Yang, Y J; Wang, L H

    2015-10-28

    The physicochemical properties of noble metal nanocrystals depend strongly on their size and shape, and it is becoming clear that the design and facile synthesis of particular nanostructures with tailored shape and size is especially important. Herein a novel class of hydrangea flower-like hierarchical gold nanostructures with tunable surface topographies and optical properties are prepared for the first time by a facile, one-pot, seedless synthesis using ascorbic acid (AA) to reduce hydrogen tetrachloroaurate (HAuCl4) in the presence of (1-hexadecyl)trimethylammonium chloride (CTAC). The morphologies of the synthesized gold nanoflowers are controlled and fine-tuned by varying the synthetic conditions such as the concentration of reagents and the growth temperature. Due to their unique hierarchical three-dimensional (3D) structures with rich hot spots, these gold nanoflowers exhibit an efficient performance in single-particle surface-enhanced Raman scattering (SERS). The work stands out as an interesting approach for anisotropic particle synthesis and morphological control, and the proposed novel, hierarchical gold nanoflowers have a number of exciting potential applications in SERS-based sensors. PMID:26416701

  12. Search for millisecond pulsars at the GMRT and the exotic discoveries

    NASA Astrophysics Data System (ADS)

    Bhaswati Bhattacharyya, Bhaswati

    There are, arguably, no other astronomical object whose discovery and subsequent studies provides more insight in such a rich variety of physics and astrophysics than the millisecond pulsars (MSPs). MSPs are a small sub-class of pulsars, rotating with periods of only a few milliseconds and due to their extraordinary rotational stability, MSPs can be considered as astrophysical clocks. The search for such exotic objects will not only enhance the MSP population, but will also allow much wider probe to explore their evolutionary history. We have discovered six MSPs with much diverse characteristics at the positions of Fermi LAT unassociated sources using the GMRT. Being the first galactic disk millisecond pulsars discovered at the GMRT, these discoveries are very important scientific achievement from India and illustrate the importance of low-frequency search for nearby millisecond pulsars. The discovery of these precise astrophysical clocks demands much finer grid in search phase space, which is completely driven by the number crunching capability of the High Performance Compute engine. The discoveries of binary MSPs in exotic evolutionary phases demands complete 3-D search. For example, 7.5 Tflops of compute power is used for the discovery of a very compact binary MSP, a Black Widow pulsar. This pulsar eclipses for about 13% of its orbit by a very low-mass companion (0.017 M_{?}). Such Black Widow pulsars are missing link between the isolated and fully recycled pulsars, where the pulsar is ablating its companion creating significant amount of intra-binary material to obscure the pulsar emission. Radio timing ephemeris allowed us to detect the gamma-ray pulsations from this millisecond pulsar. The details of the GMRT discoveries, the interesting results from our observations and the possible scientific impact of the discoveries of such exotic systems will be illustrated in this presentation.

  13. Low-frequency GMRT observations of the magnetic Bp star HR Lup (HD 133880)

    NASA Astrophysics Data System (ADS)

    George, Samuel J.; Stevens, Ian R.

    2012-06-01

    We present radio observations of the magnetic chemically peculiar Bp star HR Lup (HD 133880) at 647 and 277 MHz with the GMRT. At both frequencies the source is not detected but we are able to determine upper limits to the emission. The 647 MHz limits are particularly useful, with a 5σ value of 0.45 mJy. Also, no large enhancements of the emission were seen. The non-detections, along with previously published higher frequency detections, provide evidence that an optically thick gyrosynchrotron model is the correct mechanism for the radio emission of HR Lup.

  14. The Extended GMRT Radio Halo Survey. II. Further results and analysis of the full sample

    NASA Astrophysics Data System (ADS)

    Kale, R.; Venturi, T.; Giacintucci, S.; Dallacasa, D.; Cassano, R.; Brunetti, G.; Cuciti, V.; Macario, G.; Athreya, R.

    2015-07-01

    The intra-cluster medium contains cosmic rays and magnetic fields that are manifested through the large scale synchrotron sources, termed radio haloes, relics, and mini-haloes. The Extended Giant Metrewave Radio Telescope (GMRT) Radio Halo Survey (EGRHS) is an extension of the GMRT Radio Halo Survey (GRHS) designed to search for radio haloes using GMRT 610/235 MHz observations. The GRHS and EGRHS consists of 64 clusters in the redshift range 0.2-0.4 that have an X-ray luminosity larger than 5 × 1044 erg s-1 in the 0.1-2.4 keV band and declination, δ > -31° in the REFLEX and eBCS X-ray cluster catalogues. In this second paper in the series, GMRT 610/235 MHz data on the last batch of 11 galaxy clusters and the statistical analysis of the full sample are presented. A new mini-halo in RX J2129.6+0005 and candidate diffuse sources in Z5247, A2552, and Z1953 have been discovered. A unique feature of this survey are the upper limits on the detections of 1 Mpc sized radio haloes; 4 new are presented here, making a total of 31 in the survey. Of the sample, 58 clusters with adequately sensitive radio information were used to obtain the most accurate occurrence fractions so far. The occurrence fractions of radio haloes, mini-haloes and relics in our sample are ~22%, ~16% and ~5%, respectively. The P1.4 GHz-LX diagrams for the radio haloes and mini-haloes are presented. The morphological estimators - centroid shift (w), concentration parameter (c), and power ratios (P3/P0) derived from the Chandra X-ray images - are used as proxies for the dynamical states of the GRHS and EGRHS clusters. The clusters with radio haloes and mini-haloes occupy distinct quadrants in the c-w, c-P3/P0 and w-P3/P0 planes, corresponding to the more and less morphological disturbance, respectively. The non-detections span both the quadrants. Appendices are available in electronic form at http://www.aanda.org

  15. Five Years of Multi-frequency Monitoring of GRB030329 Afterglow Using the GMRT and WSRT

    SciTech Connect

    Kamble, Atish; Wijers, Ralph; Rol, Evert; Horst, A. J. van der; Kouveliotou, Chryssa; Bhattacharya, D.; Chandra, C. H. Ishwara; Resmi, L.; Strom, R.

    2009-05-25

    GRB 030329 displayed one of the brightest optical afterglows ever. We have followed the radio afterglow of GRB 030329 for over 5 years using the GMRT and WSRT at low radio frequencies. This is the longest as well as the lowest frequency follow up of any GRB afterglow ever.Radio observations of a GRB afterglow provide a unique probe of the physics of the blast wave at late times, when the expansion of the fireball slows down to non-relativistic speeds. Our GMRT-WSRT observations suggest that the afterglow of GRB030329 entered the non-relativistic phase around 60 days after the burst. The estimate of the fireball energy content, {approx}10{sup 51} erg, in this near-isotropic phase is much less susceptible to the collimation-related uncertainties arising in the relativistic phase. We have also been closely monitoring the evolution of the afterglow to look for possible signatures of emission from a counter jet, but no conclusive evidence has so far been found.

  16. A complete radio study of SNR G15.4+0.1 from new GMRT observations

    NASA Astrophysics Data System (ADS)

    Supan, L.; Castelletti, G.; Joshi, B. C.; Surnis, M. P.; Supanitsky, D.

    2015-04-01

    Aims: The supernova remnant (SNR) G15.4+0.1 is considered to be the possible counterpart of the ?-ray source HESS J1818-154. With the goal of getting a complete view of this remnant and understanding the nature of the ?-ray flux, we conducted a detailed radio study that includes the search for pulsations and a model of the broadband emission for the SNR G15.4+0.1/HESS J1818-154 system. Methods: Low-frequency imaging at 624 MHz and pulsar observations at 624 and 1404 MHz towards G15.4+0.1 were carried out with the Giant Metrewave Radio Telescope (GMRT). We correlated the new radio data with observations of the source at X-ray and infrared wavelengths from XMM-Newton and Herschel observatories, respectively. To characterize the neutral hydrogen (HI) medium towards G15.4+0.1, we used data from the Southern Galactic Plane Survey. We modelled the spectral energy distribution (SED) using both hadronic and leptonic scenarios. Results: From the combination of the new GMRT observations with existing data, we derived a continuum spectral index ? = -0.62 0.03 for the whole remnant. The local synchrotron spectra of G15.4+0.1, calculated from the combination of the GMRT data with 330 MHz observations from the Very Large Array, tends to be flatter in the central part of the remnant, accompanying the region where the blast wave is impinging molecular gas. No spectral index trace was found indicating the radio counterpart to the pulsar wind nebula proposed from X-ray observations. In addition, the search for radio pulsations yielded negative results. Emission at far-infrared wavelengths is observed in the region where the SNR shock is interacting with dense molecular clumps. We also identified HI features forming a shell that wraps most of the outer border of G15.4+0.1. Characteristic parameters were estimated for the shocked HI gas. We found that either a purely hadronic or leptonic model is compatible with the broadband emission known so far.

  17. Improved foreground removal in GMRT 610 MHz observations towards redshifted 21-cm tomography

    NASA Astrophysics Data System (ADS)

    Ghosh, Abhik; Bharadwaj, Somnath; Ali, Sk. Saiyad; Chengalur, Jayaram N.

    2011-12-01

    Foreground removal is a challenge for 21-cm tomography of the high-redshift Universe. We use archival Giant Metrewave Radio Telescope (GMRT) data (obtained for completely different astronomical goals) to estimate the foregrounds at a redshift of 1. The statistic we use is the cross power spectrum between two frequencies separated by ?? at the angular multipole ?, or equivalently the multi-frequency angular power spectrum C?(??). An earlier measurement of C?(??) using these data had revealed the presence of oscillatory patterns along ??, which turned out to be a severe impediment for foreground removal. Using the same data, in this paper we show that it is possible to considerably reduce these oscillations by suppressing the sidelobe response of the primary antenna elements. The suppression works best at the angular multipoles ? for which there is a dense sampling of the u-v plane. For three angular multipoles ?= 1405, 1602 and 1876, this sidelobe suppression along with a low order polynomial fitting completely results in residuals of (? 0.02 mK2), consistent with the noise at the 3? level. Since the polynomial fitting is done after estimation of the power spectrum it can be ensured that the estimation of the H I signal is not biased. The corresponding 99 per cent upper limit on the H I signal is ?, where ? is the mean neutral fraction and b is the bias.

  18. GMRT radio continuum study of Wolf-Rayet galaxies - I. NGC 4214 and NGC 4449

    NASA Astrophysics Data System (ADS)

    Srivastava, S.; Kantharia, N. G.; Basu, Aritra; Srivastava, D. C.; Ananthakrishnan, S.

    2014-09-01

    We report low-frequency observations of Wolf-Rayet galaxies, NGC 4214 and NGC 4449 at 610, 325 and 150 MHz, using the Giant Meterwave Radio Telescope (GMRT). We detect diffuse extended emission from NGC 4214 at and NGC 4449. NGC 4449 is observed to be five times more radio luminous than NGC 4214, indicating vigorous star formation. We estimate synchrotron spectral index after separating the thermal free-free emission and obtain ?nt = -0.63 0.04 (S? ? ^{? _nt}) for NGC 4214 and -0.49 0.02 for NGC 4449. About 22 per cent of the total radio emission from NGC 4214 and 9 per cent from NGC 4449 at 610 MHz is thermal in origin. We also study the spectra of two compact star-forming regions in NGC 4214 from 325 MHz to 15 GHz and obtain ?nt = -0.32 0.02 for NGC 4214-I and ?nt = -0.94 0.12 for NGC 4214-II. The luminosities of these star-forming regions (1019 WHz-1) appear to be similar to those in circumnuclear rings in normal disc galaxies observed with similar linear resolution. We detect the supernova remnant SNR J1228+441 in NGC 4449 and estimate the spectral index of the emission between 325 and 610 MHz to be -1.8 in the epoch 2008-2009. The galaxies follow the radio-FIR correlation slopes suggesting that star formation in Wolf-Rayet galaxies, which are low-metallicity systems, are similar to that of normal disc galaxies.

  19. The GMRT High Resolution Southern Sky Survey for Pulsars and Transients. I. Survey Description and Initial Discoveries

    NASA Astrophysics Data System (ADS)

    Bhattacharyya, B.; Cooper, S.; Malenta, M.; Roy, J.; Chengalur, J.; Keith, M.; Kudale, S.; McLaughlin, M.; Ransom, S. M.; Ray, P. S.; Stappers, B. W.

    2016-02-01

    We are conducting a survey for pulsars and transients using the Giant Metrewave Radio Telescope (GMRT). The GMRT High Resolution Southern Sky (GHRSS) survey is an off-Galactic plane (| b| > 5) survey in the declination range ‑40° to ‑54° at 322 MHz. With the high time (up to 30.72 μs) and frequency (up to 0.016275 MHz) resolution observing modes, the 5σ detection limit is 0.5 mJy for a 2 ms pulsar with a 10% duty cycle at 322 MHz. The total GHRSS sky coverage of 2866 deg2 will result from 1953 pointings, each covering 1.8 deg2. The 10σ detection limit for a 5 ms transient burst is 1.6 Jy for the GHRSS survey. In addition, the GHRSS survey can reveal transient events like rotating radio transients or fast radio bursts. With 35% of the survey completed (i.e., 1000 deg2), we report the discovery of 10 pulsars, 1 of which is a millisecond pulsar (MSP), which is among the highest pulsar per square degree discovery rates for any off-Galactic plane survey. We re-detected 23 known in-beam pulsars. Utilizing the imaging capability of the GMRT, we also localized four of the GHRSS pulsars (including the MSP) in the gated image plane within ±10″. We demonstrated rapid convergence in pulsar timing with a more precise position than is possible with single-dish discoveries. We also show that we can localize the brightest transient sources with simultaneously obtained lower time resolution imaging data, demonstrating a technique that may have application in the Square Kilometre Array.

  20. Map of Mars' Topography

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Map of Mars' topography with zonal spherical harmonic degree 1 (COM/COF offset along the polar z-axis) removed. The projection is rectangular to show topography from pole to pole. Note the general similarity in elevation between the northern and southern hemispheres. The figure highlights the two other significant components of martian topography: the Tharsis province and the Hellas impact basin. Here we have not removed shorter-wavelength topographic features, including those comprising the dichotomy boundary scarp.

  1. Brightest cluster galaxies in the extended GMRT radio halo cluster sample. Radio properties and cluster dynamics

    NASA Astrophysics Data System (ADS)

    Kale, R.; Venturi, T.; Cassano, R.; Giacintucci, S.; Bardelli, S.; Dallacasa, D.; Zucca, E.

    2015-09-01

    Aims: First-ranked galaxies in clusters, usually referred to as brightest cluster galaxies (BCGs), show exceptional properties over the whole electromagnetic spectrum. They are the most massive elliptical galaxies and show the highest probability to be radio loud. Moreover, their special location at the centres of galaxy clusters raises the question of the role of the environment in shaping their radio properties. In the attempt to separate the effect of the galaxy mass and of the environment on their statistical radio properties, we investigate the possible dependence of the occurrence of radio loudness and of the fractional radio luminosity function on the dynamical state of the hosting cluster. Methods: We studied the radio properties of the BCGs in the Extended GMRT Radio Halo Survey (EGRHS), which consists of 65 clusters in the redshift range 0.2-0.4, with X-ray luminosity LX ≥ 5 × 1044 erg s-1, and quantitative information on their dynamical state from high-quality Chandra imaging. We obtained a statistical sample of 59 BCGs, which we divided into two classes, depending on whether the dynamical state of the host cluster was merging (M) or relaxed (R). Results: Of the 59 BCGs, 28 are radio loud and 31 are radio quiet. The radio-loud sources are favourably located in relaxed clusters (71%), while the reverse is true for the radio-quiet BCGs, which are mostly located in merging systems (81%). The fractional radio luminosity function for the BCGs in merging and relaxed clusters is different, and it is considerably higher for BCGs in relaxed clusters, where the total fraction of radio loudness reaches almost 90%, to be compared to the ~30% in merging clusters. For relaxed clusters, we found a positive correlation between the radio power of the BCGs and the strength of the cool core, consistent with previous studies on local samples. Conclusions: Our study suggests that the radio loudness of the BCGs strongly depends on the cluster dynamics; their fraction is considerably higher in relaxed clusters. We compare our results with similar investigations and briefly discuss them in the framework of AGN feedback.

  2. Facile Synthesis of Conductive Polypyrrole Wrinkle Topographies on Polydimethylsiloxane via a Swelling-Deswelling Process and Their Potential Uses in Tissue Engineering.

    PubMed

    Aufan, M Rifqi; Sumi, Yang; Kim, Semin; Lee, Jae Young

    2015-10-28

    Electrically conducting biomaterials have gained great attention in various biomedical studies especially to influence cell and tissue responses. In addition, wrinkling can present a unique topography that can modulate cell-material interactions. In this study, we developed a simple method to create wrinkle topographies of conductive polypyrrole (wPPy) on soft polydimethylsiloxane surfaces via a swelling-deswelling process during and after PPy polymerization and by varying the thickness of the PPy top layers. As a result, various features of wPPy in the range of the nano- and microscales were successfully obtained. In vitro cell culture studies with NIH 3T3 fibroblasts and PC12 neuronal cells indicated that the conductive wrinkle topographies promote cell adhesion and neurite outgrowth of PC12 cells. Our studies help to elucidate the design of the surface coating and patterning of conducting polymers, which will enable us to simultaneously provide topographical and electrical signals to improve cell-surface interactions for potential tissue-engineering applications. PMID:26444932

  3. OpenTopography

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  4. Dynamic Topography Revisited

    NASA Astrophysics Data System (ADS)

    Moresi, Louis

    2015-04-01

    Dynamic Topography Revisited Dynamic topography is usually considered to be one of the trinity of contributing causes to the Earth's non-hydrostatic topography along with the long-term elastic strength of the lithosphere and isostatic responses to density anomalies within the lithosphere. Dynamic topography, thought of this way, is what is left over when other sources of support have been eliminated. An alternate and explicit definition of dynamic topography is that deflection of the surface which is attributable to creeping viscous flow. The problem with the first definition of dynamic topography is 1) that the lithosphere is almost certainly a visco-elastic / brittle layer with no absolute boundary between flowing and static regions, and 2) the lithosphere is, a thermal / compositional boundary layer in which some buoyancy is attributable to immutable, intrinsic density variations and some is due to thermal anomalies which are coupled to the flow. In each case, it is difficult to draw a sharp line between each contribution to the overall topography. The second definition of dynamic topography does seem cleaner / more precise but it suffers from the problem that it is not measurable in practice. On the other hand, this approach has resulted in a rich literature concerning the analysis of large scale geoid and topography and the relation to buoyancy and mechanical properties of the Earth [e.g. refs 1,2,3] In convection models with viscous, elastic, brittle rheology and compositional buoyancy, however, it is possible to examine how the surface topography (and geoid) are supported and how different ways of interpreting the "observable" fields introduce different biases. This is what we will do. References (a.k.a. homework) [1] Hager, B. H., R. W. Clayton, M. A. Richards, R. P. Comer, and A. M. Dziewonski (1985), Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313(6003), 541-545, doi:10.1038/313541a0. [2] Parsons, B., and S. Daly (1983), The relationship between surface topography, gravity anomalies, and temperature structure of convection, Journal of Geophysical Research: Solid Earth (1978-2012), 88(B2), 1129-1144, doi:10.1029/JB088iB02p01129. [3] Robinson, E. M., B. Parsons, and S. F. Daly (1987), The effect of a shallow low viscosity zone on the apparent compensation of mid-plate swells, Earth and Planetary Science Letters, 82(3-4), 335-348, doi:10.1016/0012-821X(87)90207-X.

  5. X Ray Topography

    ERIC Educational Resources Information Center

    Balchin, A. A.

    1974-01-01

    Discusses some aspects in X-ray topography, including formation of dislocations, characteristics of stacking faults, x-ray contrast in defect inspection, Berg-Barrett technique, and Lang traversing crystal and Borrmann's methods. (CC)

  6. GMRT observations of the group Holmberg 124: Evolution by tidal forces and ram pressure?

    NASA Astrophysics Data System (ADS)

    Kantharia, N. G.; Ananthakrishnan, S.; Nityananda, R.; Hota, A.

    2005-05-01

    We report new radio continuum and 21 cm HI observations using the Giant Metrewave Radio Telescope (GMRT) of the group Holmberg 124 (Ho 124) comprising four late-type galaxies, namely NGC 2820, Mrk 108, NGC 2814 and NGC 2805. The three galaxies, NGC 2820, Mrk 108 and NGC 2814 which are closely located in the sky plane have clearly undergone tidal interactions as seen from the various morphological tidal signatures and debris. Moreover we note various features in the group members which we believe might be due to ram pressure. In this paper, we describe four interesting results emerging from our observations: a) detection of the tidal radio continuum bridge at 330 MHz connecting the galaxies NGC 2820+Mrk 108 with NGC 2814. The radio bridge was discovered at 1465 MHz by van der Hulst & Hummel (1985, A&A, 150, 17). We find that the bridge has a fairly steep spectrum with a spectral index ? (S ? ??) of -1.8+0.3-0.2 which is much steeper than the -0.8 quoted by van der Hulst & Hummel (1985); b) detection of other tidal features like the tilted HI and radio continuum disk of NGC 2814, a HI streamer and a radio continuum tail arising from the south of NGC 2814. We also report the detection of a possible tidal dwarf galaxy in HI; c) sharp truncation in the HI distribution in the south of NGC 2820 and in the HI and radio continuum distribution in the north of NGC 2814. The optical disks in both the cases look undisturbed. As pointed out by Davis et al. (1997, AJ, 114, 613), ram pressure affects different components of the interstellar medium to varying degrees. Simple estimates of pressure in different components of the interstellar medium (radio continuum, H? and HI) in NGC 2820 indicate that ram pressure will significantly influence HI; d) detection of a large one-sided HI loop to the north of NGC 2820. No radio continuum emission or H? emission is associated with the HI loop. We discuss various scenarios for the origin of this loop including a central starburst, ram pressure stripping and tidal interaction. We do not support the central starburst scenario since the loop is not detected in ionized gas. Using the upper limit on X-ray luminosity of Ho 124 (Mulchaey et al. 2003, ApJS, 145, 39), we estimate an upper limit on the intragroup medium (IGrM) density of 8.810-4 cm-3. For half this electron density, we estimate the ram pressure force of the IGrM to be comparable to the gravitational pull of the disk of NGC 2820. Since tidal interaction has obviously influenced the group, we suggest that the loop could have formed by ram pressure stripping if tidal effects had reduced the surface density of HI in NGC 2820. From the complex observational picture of Ho 124 and the numerical estimates, we suggest that the evolution of the Ho 124 group may be governed by both tidal forces due to the interaction and the ram pressure due to motion of the member galaxies in the IGrM and that the IGrM densities should not be too low (i.e. ? 410-4). However this needs to be verified by further observations.

  7. Universal multifractal Martian topography

    NASA Astrophysics Data System (ADS)

    Landais, F.; Schmidt, F.; Lovejoy, S.

    2015-11-01

    In the present study, we investigate the scaling properties of the topography of Mars. Planetary topographic fields are well known to roughly exhibit (mono)fractal behavior. Indeed, the fractal formalism reproduces much of the variability observed in topography. Still, a single fractal dimension is not enough to explain the huge variability and intermittency. Previous studies have claimed that fractal dimensions might be different from one region to another, excluding a general description at the planetary scale. In this article, we analyze the Martian topographic data with a multifractal formalism to study the scaling intermittency. In the multifractal paradigm, the apparent local variation of the fractal dimension is interpreted as a statistical property of multifractal fields. We analyze the topography measured with the Mars Orbiter Laser altimeter (MOLA) at 300 m horizontal resolution, 1 m vertical resolution. We adapted the Haar fluctuation method to the irregularly sampled signal. The results suggest a multifractal behavior from the planetary scale down to 10 km. From 10 to 300 m, the topography seems to be simple monofractal. This transition indicates a significant change in the geological processes governing the Red Planet's surface.

  8. The Extended GMRT Radio Halo Survey. I. New upper limits on radio halos and mini-halos

    NASA Astrophysics Data System (ADS)

    Kale, R.; Venturi, T.; Giacintucci, S.; Dallacasa, D.; Cassano, R.; Brunetti, G.; Macario, G.; Athreya, R.

    2013-09-01

    Context. A fraction of galaxy clusters host diffuse radio sources called radio halos, radio relics and mini-halos. These are associated with the relativistic electrons and magnetic fields present on ~Mpc scales in the intra-cluster medium. Aims: We aim to carry out a systematic radio survey of all luminous galaxy clusters selected from the REFLEX and eBCS X-ray catalogues with the Giant Metrewave Radio Telescope, to understand the statistical properties of the diffuse radio emission in galaxy clusters. Methods: We present the sample and first results from the Extended GMRT Radio Halo Survey (EGRHS), which is an extension of the GMRT Radio Halo Survey (GRHS, Venturi et al. 2007, 2008). Analysis of radio data at 610/ 235/ 325 MHz on 12 galaxy clusters are presented. Results: We report the detection of a newly discovered mini-halo in the cluster RX J1532.9+3021 at 610 MHz. The presence of a small-scale relic (~200 kpc) is suspected in the cluster Z348. We do not detect cluster-scale diffuse emission in 11 clusters. Robust upper limits on the detection of radio halo of size of 1 Mpc are determined. We also present upper limits on the detections of mini-halos in a sub-sample of cool-core clusters. The upper limits for radio halos and mini-halos are plotted in the radio power- X-ray luminosity plane and the correlations are discussed. Diffuse extended emission that is not related to the target clusters, but detected as by-products in the sensitive images of two of the cluster fields (A689 and RX J0439.0+0715) is also reported. Conclusions: Based on the information about the presence of radio halos (or upper limits), available on 48 clusters out of the total sample of 67 clusters (EGRHS+GRHS), we find that 23 7% of the clusters host radio halos. The radio halo fraction rises to 31 11%, when only the clusters with X-ray luminosities >8 1044 erg s-1 are considered. Mini-halos are found in ~50% of cool-core clusters. A qualitative examination of the X-ray images of the clusters with no diffuse radio emission indicates that a majority of these clusters do not show extreme dynamical disturbances and supports the idea that mergers play an important role in generating radio halos and relics. The analysis of the full sample will be presented in a future work. Appendix A is available in electronic form at http://www.aanda.org

  9. The Dawn Topography Investigation

    NASA Technical Reports Server (NTRS)

    Raymond, C. A.; Jaumann, R.; Nathues, A.; Sierks, H.; Roatsch, T.; Preusker, E; Scholten, F.; Gaskell, R. W.; Jorda, L.; Keller, H.-U.; Zuber, M. T.; Smith, D. E.; Mastrodemos, N.; Mottola, S.

    2011-01-01

    The objective of the Dawn topography investigation is to derive the detailed shapes of 4 Vesta and 1 Ceres in order to create orthorectified image mosaics for geologic interpretation, as well as to study the asteroids' landforms, interior structure, and the processes that have modified their surfaces over geologic time. In this paper we describe our approaches for producing shape models, plans for acquiring the needed image data for Vesta, and the results of a numerical simulation of the Vesta mapping campaign that quantify the expected accuracy of our results. Multi-angle images obtained by Dawn's framing camera will be used to create topographic models with 100 m/pixel horizontal resolution and 10 m height accuracy at Vesta, and 200 m/pixel horizontal resolution and 20 m height accuracy at Ceres. Two different techniques, stereophotogrammetry and stereophotoclinometry, are employed to model the shape; these models will be merged with the asteroidal gravity fields obtained by Dawn to produce geodetically controlled topographic models for each body. The resulting digital topography models, together with the gravity data, will reveal the tectonic, volcanic and impact history of Vesta, and enable co-registration of data sets to determine Vesta's geologic history. At Ceres, the topography will likely reveal much about processes of surface modification as well as the internal structure and evolution of this dwarf planet.

  10. Toward optical coherence topography

    NASA Astrophysics Data System (ADS)

    Sayegh, Samir; Jiang, Yanshui

    2012-03-01

    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.

  11. Profile measuring and topography modeling of aluminum alloy sheet surface

    NASA Astrophysics Data System (ADS)

    Zhang, Wei; Li, Zhigang

    2006-11-01

    With the development of lightweight vehicles, aluminum alloy sheet plays a more and more important role in auto panel production because of its high strength and low mass. However, aluminum alloy sheet is more difficult to forming than steel and its contact and friction behavior with the die surface in warm forming is more complicated. In order to study the laws of the contact and friction behavior, the topography data of aluminum alloy sheet surface should be obtained first so that the topography model can be set up. The authors introduce the principle and the performance of AF-LI Contact and Non-contact Synthesis Measuring Profilometer, get the topography data of aluminum alloy sheet surface by using contact measuring method. Then a statistical topography model of aluminum alloy sheet surface is set up based on the data.

  12. Antarctic topography from balloons

    NASA Technical Reports Server (NTRS)

    Levanon, N.; Julian, P. R.; Suomi, V. E.

    1977-01-01

    A description is presented of an investigation involving the collection of Antarctic ice sheet surface topography data by means of balloons, floating at an altitude of about 12.5 km, which traversed the Antarctic during its 1975 summer. These balloons were part of 411 constant density balloons launched in the Southern Hemisphere during the Tropical Wind, Energy conversion and Reference Level Experiment. The three sensors carried by each balloon included a radio altimeter, a pressure sensor, and an ambient temperature sensor. Data transmitted by a balloon are received by a measuring system on board the Nimbus-6 satellite. A synoptic map is presented of the 150 mbar pressure surface at 1200 GMT, December 11, 1975.

  13. RADAR Reveals Titan Topography

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

    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

  14. Topography of Io (color)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    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

  15. Topography of chance

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo I.; Cohen, Morrel H.

    2013-11-01

    We present a model of multiplicative Langevin dynamics that is based on two foundations: the Langevin equation and the notion of multiplicative evolution. The model is a nonlinear mechanism transforming a white-noise input to a dynamic-equilibrium output, using a single control: an underlying convex U-shaped potential function. The output is quantified by a stationary density which can attain a given number of shapes and a given number of randomness categories. The model generates each admissible combination of the output's shape and randomness in a universal and robust fashion. Moreover, practically all the probability distributions that are supported on the positive half-line, and that are commonly encountered and applied across the sciences, can be reverse engineered by this model. Hence, this model is a universal equilibrium mechanism, in the context of multiplicative dynamics, for the robust generation of chance: the model's output. In turn, the properties of the produced chance, the output's shape and randomness, are determined with mathematical precision by the control's landscape, its topography. Thus, a topographic map of chance is established. As a particular application, probability distributions with power-law tails are shown to be universally and robustly generated by controls on the edge of convexity: convex U-shaped potential functions with asymptotically linear wings.

  16. Fabrication of gradient colloidal topography.

    PubMed

    Zhang, Jilin; Xue, Longjian; Han, Yanchun

    2005-06-21

    A rather simple but yet effective way to self-assemble polystyrene (PS) beads in gradient colloidal crystal topography is proposed. The PS bead concentration, solvent, and substrate have a big effect on the colloidal crystal topography. Whether the gradient-shaped crystals can form or not depends on the Bond number [Bo; the ratio of gravitational potential energy (G) to adhesive energy (E(a)), or gravitational to capillary forces]. When Bo < 1, that is, the capillary force dominates over the gravitational force, the liquid meniscus is stable. The gradient-shaped crystals can form. Otherwise, PS beads form a uniform multilayer structure. PMID:15952805

  17. X-ray Topography in Protein Crystals

    NASA Astrophysics Data System (ADS)

    Kojima, Kenichi; Tachibana, Masaru

    X-ray topography, especially synchrotron X-ray topography, provides a useful tool for the characterization of protein crystals in order to characterize the defects. We observed clear images of dislocations in hen-egg white lysozyme crystals. In this article we overviewed the research on crystal defects, especially dislocations of protein crystals by synchrotron X-ray topography.

  18. The Shuttle Radar Topography Mission

    NASA Astrophysics Data System (ADS)

    Farr, Tom G.; Rosen, Paul A.; Caro, Edward; Crippen, Robert; Duren, Riley; Hensley, Scott; Kobrick, Michael; Paller, Mimi; Rodriguez, Ernesto; Roth, Ladislav; Seal, David; Shaffer, Scott; Shimada, Joanne; Umland, Jeffrey; Werner, Marian; Oskin, Michael; Burbank, Douglas; Alsdorf, Douglas

    2007-06-01

    The Shuttle Radar Topography Mission produced the most complete, highest-resolution digital elevation model of the Earth. The project was a joint endeavor of NASA, the National Geospatial-Intelligence Agency, and the German and Italian Space Agencies and flew in February 2000. It used dual radar antennas to acquire interferometric radar data, processed to digital topographic data at 1 arc sec resolution. Details of the development, flight operations, data processing, and products are provided for users of this revolutionary data set.

  19. Shape and Topography of Mars

    NASA Technical Reports Server (NTRS)

    Smith, David E.

    2000-01-01

    Observations by the Mars Orbiter Laser Altimeter (MOLA) on the Mars Global Surveyor (MGS) spacecraft are showing a new planet in its range of topography and in the detail of the geological features. MGS arrived at Mars in Sept 1997 and since Feb. 28, 1999 the laser altimeter has operated continuously. By the end of April 2000 MOLA had acquired over 350 million measurements of the planet's shape and topography. These observations show a strong down-hill topographic gradient from the south pole to the north pole with an extremely low and flat basin encompassing most of the northern hemisphere. Large outflow channels are seen in the Chyrse region that strongly suggest considerable quantities of water once flowed into the lower northern hemisphere from the south. The northern icecap, which rises to a height of three kilometers above the surrounding terrain, is shown to be largely composed of water ice and at the center of a large basin. The southern hemisphere is about five kilometers higher than the low northern plains and dominated by the Hellas impact basin whose ejecta is the major contributor to the topography of the hemisphere and the crustal dichotomy. The south polar icecap, which is part of a much larger region of layered terrain composed of water ice and dust, reaches an elevation of nearly five kilometers and except for the large Tharsis volcanoes is the highest part of the planet.

  20. Earth rotation and core topography

    NASA Technical Reports Server (NTRS)

    Hager, Bradford H.; Clayton, Robert W.; Spieth, Mary Ann

    1988-01-01

    The NASA Geodynamics program has as one of its missions highly accurate monitoring of polar motion, including changes in length of day (LOD). These observations place fundamental constraints on processes occurring in the atmosphere, in the mantle, and in the core of the planet. Short-timescale (t less than or approx 1 yr) variations in LOD are mainly the result of interaction between the atmosphere and the solid earth, while variations in LOD on decade timescales result from the exchange of angular momentum between the mantle and the fluid core. One mechanism for this exchange of angular momentum is through topographic coupling between pressure variations associated with flow in the core interacting with topography at the core-mantel boundary (CMB). Work done under another NASA grant addressing the origin of long-wavelength geoid anomalies as well as evidence from seismology, resulted in several models of CMB topography. The purpose of work supported by NAG5-819 was to study further the problem of CMB topography, using geodesy, fluid mechanics, geomagnetics, and seismology. This is a final report.

  1. Topography, Cell Response, and Nerve Regeneration

    PubMed Central

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

    2010-01-01

    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

  2. Precision Measurement Of Corneal Topography

    NASA Astrophysics Data System (ADS)

    Yoder, Paul R.; Macri, Timothy F.; Telfair, William B.; Bennett, Peter S.; Martin, Clifford A.; Warner, John W.

    1989-05-01

    We describe a new electro-optical device being developed to provide precise measurements of the three-dimensional topography of the human cornea. This device, called a digital keratoscope, is intended primarily for use in preparing for and determining the effect of corneal surgery procedures such as laser refractive keratectomy, radial keratotomy or corneal transplant on the refractive power of the cornea. It also may serve as an aid in prescribing contact lenses. The basic design features of the hardware and of the associated computer software are discussed, the means for alignment and calibration are described and typical results are given.

  3. Plasma processing for nanostructured topographies

    NASA Astrophysics Data System (ADS)

    Riedel, Nicholas Alfred

    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.

  4. Venus topography - A harmonic analysis

    NASA Astrophysics Data System (ADS)

    Bills, B. G.; Kobrick, M.

    1985-01-01

    A model of Venusian global topography has been obtained by fitting an eighteenth-degree harmonic series to Pioneer Venus orbiter radar altimeter data. The mean radius is (6051.45 + or - 0.04) km. The corresponding mean density is (5244.8 + or 0.5) kg/cu m. The center of figure is displaced from the center of mass by (0.339 + or - 0.088) km towards (6.6 + or 10.1) deg N, (148. 8 + or - 7.7) deg. The figure of Venus is distinctly triaxial, but the orientation and magnitudes of the principal topographic axes correlate rather poorly with the gravitational principal axes. However, the higher-degree harmonics of topography and gravity are significantly correlated. The topographic variance spectrum of Venus is very similar in form to those of the moon, Mars, and especially earth. It is suggested that this spectral similarity simply reflects a statistical balance between constructional and degradational geomorphic proceses. Venus and earth are particularly similar (and differ from the moon and Mars) in that the larger bodies both exhibit a significant low degree deficit (relative to the extrapolated trend of the higher harmonics).

  5. Topography from single radar images.

    PubMed

    Wildey, R L

    1984-04-13

    A mathematical theory and a corresponding numerical procedure have been developed to produce digital topography from radar images as digital photometric arrays. Thus, as radargrammetry is to photogrammetry, so radarclinometry is to photoclinometry. Photoclinometry encompasses a fundamental indeterminacy principle even for terrain that is homogeneous in normal albedo, because the surface normal consistent with a given reflected specific intensity is not unique. A geometric locus of such normal directions is implied, which generates a surface. For microwave backscatter, in specific application to radarclinometry, this surface is a cone whose half-angle is the incidence angle, whose axis contains the radar, and whose apex coincides with the terrain point. Although the indeterminacy can be removed if a properly directed profile of ground truth is available as a constraint, such is seldom the case. In its absence, an auxiliary assumption, such as that the strike line runs perpendicular to the illumination line, is needed. If metric integrity is a goal, then this is an absurd assumption. Herein, "the hypothesis of local cylindricity" has been assumed, a premise regarding the nature of topographic curvature that seems more realistic and that makes possible the production of topography as a set of parallel line integrals. PMID:17744680

  6. Predicting channel bed topography in hydraulic falls

    NASA Astrophysics Data System (ADS)

    Tam, Alexander; Yu, Zheng; Kelso, Richard M.; Binder, Benjamin J.

    2015-11-01

    We consider inverse methods for predicting the channel bed topography in experiments of hydraulic falls. Nonlinear solutions and weakly nonlinear approximations from Euler-based models are compared to experimental observations. Accurate predictions are obtained for the maximum height of the topography and its constant horizontal level far downstream using the nonlinear method. The weakly nonlinear approximation is shown only to be a good predictor of the maximum height of the topography. The error in the inverse predictions is examined and discussed.

  7. Wrinkled surface topographies of electrospun polymer fibers

    NASA Astrophysics Data System (ADS)

    Wang, Lifeng; Pai, Chia-Ling; Boyce, Mary C.; Rutledge, Gregory C.

    2009-04-01

    Electrospun polymer fibers are shown to have wrinkled surface topographies that result from buckling instabilities during processing. A glassy shell forms on the surface of the gel-like core during solvent evaporation; continued evaporation leads to a contraction mismatch between the core and shell that triggers buckling of the shell. The wrinkled topographies are quantified in terms of the critical buckling wave number and wavelength. The results explain the observed wrinkled topographies and provide a framework for designing fibers with high specific surface areas and textured/patterned surface topographies to enhance surface dominated properties in fibers and fibrous mats.

  8. Carbon Dioxide Exchange in Complex Topography

    NASA Astrophysics Data System (ADS)

    Reif, Matthias; Rotach, Mathias; Wohlfahrt, Georg; Gohm, Alexander

    2015-04-01

    On a global scale the budget of carbon dioxide (CO_2) bears a quite substantial uncertainty, which is commonly understood to be mainly due to land-surface exchange processes. In this project we investigate to what extent complex topography can amplify these land-surface exchange processes. The hypothesis is that, on the meso-scale, topography adds additional atmospheric mechanisms that drive the exchange of CO2 at the surface. This sensitivity model study investigates an idealized sine shaped valley with the atmospheric numerical model Weather Research and Forecasting (WRF) coupled to the community land model (CLM) to study the effect of complex topography on the CO2 budget compared to flat terrain. The experiment is designed to estimate the effect of the topography during maximum ecosystem exchange in summer using meteorological and ecosystem conditions at solstice, the 21. of June. Systematic variation of meteorological initial conditions, plant functional types and the topography creates an ensemble that unveils the fundamental factors that dominate the differences of CO2 between simulations with topography compared to plain surfaces in the model. The sign and magnitude of the difference between the CO2 exchange over topography and over a plain simulation are strongly dependent on the CLM plant functional type, the initial temperature, the initial relative humidity, the latitude and the area height distribution of the topography. However, in this model experiment the topography is, in the mean, a sink to the CO2 budget in the order of 5% per day.

  9. Venus - Global gravity and topography

    NASA Astrophysics Data System (ADS)

    McNamee, J. B.; Borderies, N. J.; Sjogren, W. L.

    1993-05-01

    A new gravity field determination that has been produced combines both the Pioneer Venus Orbiter (PVO) and the Magellan Doppler radio data. Comparisons between this estimate, a spherical harmonic model of degree and order 21, and previous models show that significant improvements have been made. Results are displayed as gravity contours overlaying a topographic map. We also calculate a new spherical harmonic model of topography based on Magellan altimetry, with PVO altimetry included where gaps exist in the Magellan data. This model is also of degree and order 21, so in conjunction with the gravity model, Bouguer and isostatic anomaly maps can be produced. These results are very consistent with previous results, but reveal more spatial resolution in the higher latitudes.

  10. The Shuttle Radar Topography Mission

    NASA Technical Reports Server (NTRS)

    Farr, Tom G.; Kobrick, Mike

    2000-01-01

    On February 22, 2000 Space Shuttle Endeavour landed at Kennedy Space Center, completing the highly successful 11-day flight of the Shuttle Radar Topography Mission (SRTM). Onboard were over 300 high-density tapes containing data for the highest resolution, most complete digital topographic map of Earth ever made. SRTM is a cooperative project between NASA and the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense. The mission was designed to use a single-pass radar interferometer to produce a digital elevation model (DEM) of the Earth's land surface between about 60 deg north and 56 deg south latitude. When completed, the DEM will have 30 m pixel spacing and about 15 m vertical accuracy. Two orthorectified image mosaics (one from the ascending passes with illumination from the southeast and one from descending passes with illumination from the southwest) will also be produced.

  11. Flat Subduction and Dynamic Topography

    NASA Astrophysics Data System (ADS)

    Lithgow-Bertelloni, C. R.; Dávila, F. M.; Eakin, C. M.; Crameri, F.

    2014-12-01

    Mantle dynamics manifests at the surface via the horizontal motions of plates and the vertical deflections that influence topography and the non-hydrostatic geoid. The pioneering work of Mitrovica et al. (1989) and Gurnis (1990) on this dynamic topography revolutionized our understanding of sedimentary basin formation, sea level changes and continental flooding. The temporal evolution of subduction can explain the migration of basins and even the drainage reversal of the Amazon (Shephard et al., 2012; Eakin et al., 2014). Until recently, flat subduction has been seen as enhancing downward deflection of the overriding plate and increasing flooding. However, this interpretation depends crucially on the details of the morphology and density structure of the slab, which controls the loci and amplitude of the deflection. We tend to ignore morphological details in mantle dynamics because flow can smooth out short wavelength variations. We have shown instead that details matter! Using South America as a natural laboratory because of the large changes in morphology of the Nazca slab along strike, we show that downward deflection of the overriding plate and hence basin formation, do not occur over flat segments but at the leading edge, where slabs plunge back into the mantle. This is true in both Argentina and Peru. The temporal evolution from a 'normally' dipplng slab to a flat slab leads to uplift over flat segments rather than enhanced subsidence. Critical for this result is the use of a detailed morphological model of the present-day Nazca slab with a spatial resolution of 50-100 km and based on relocated seismicity and magnetotelluric results. The density structure of the slab, due to age and the presence of overthickened crust from aseismic ridge subduction is essential. Overthickened crust leads to buoyant slabs. We reproduce formation and deposition of the Acres-Solimoes basin and the evolution of the Amazon drainage basin in Peru as well as the Mar Chiquita depression in Argentina. We explain the uplift of the paleosols of the los Llanos formation and the Fitzcarrald Arch. We show the effects of strong viscosity variations and slab dip on the extent of continental flooding.

  12. Topography and Landforms of Ecuador

    USGS Publications Warehouse

    Chirico, Peter G.; Warner, Michael B.

    2005-01-01

    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.

  13. Shuttle Radar Topography Mission (SRTM)

    USGS Publications Warehouse

    U.S. Geological Survey

    2003-01-01

    Under an agreement with the National Aeronautics and Space Administration (NASA) and the Department of Defense's National Imagery and Mapping Agency (NIMA), the U.S. Geological Survey (USGS) is now distributing elevation data from the Shuttle Radar Topography Mission (SRTM). The SRTM is a joint project between NASA and NIMA to map the Earth's land surface in three dimensions at a level of detail unprecedented for such a large area. Flown aboard the NASA Space Shuttle Endeavour February 11-22, 2000, the SRTM successfully collected data over 80 percent of the Earth's land surface, for most of the area between 60? N. and 56? S. latitude. The SRTM hardware included the Spaceborne Imaging Radar-C (SIR-C) and X-band Synthetic Aperture Radar (X-SAR) systems that had flown twice previously on other space shuttle missions. The SRTM data were collected specifically with a technique known as interferometry that allows image data from dual radar antennas to be processed for the extraction of ground heights.

  14. Shuttle Radar Topography Mission (SRTM)

    USGS Publications Warehouse

    U.S. Geological Survey

    2009-01-01

    Under an agreement with the National Aeronautics and Space Administration (NASA) and the Department of Defense's National Geospatial-Intelligence Agency (NGA), the U.S. Geological Survey (USGS) is distributing elevation data from the Shuttle Radar Topography Mission (SRTM). The SRTM is a joint project of NASA and NGA to map the Earth's land surface in three dimensions at an unprecedented level of detail. As part of space shuttle Endeavour's flight during February 11-22, 2000, the SRTM successfully collected data over 80 percent of the Earth's land surface for most of the area between latitudes 60 degrees north and 56 degrees south. The SRTM hardware included the Spaceborne Imaging Radar-C (SIR-C) and X-band Synthetic Aperture Radar (X-SAR) systems that had flown twice previously on other space shuttle missions. The SRTM data were collected with a technique known as interferometry that allows image data from dual radar antennas to be processed for the extraction of ground heights.

  15. Maps of Mars Global Topography

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Maps of Mars' global topography. The projections are Mercator to 70o latitude and stereographic at the poles with the south pole at left and north pole at right. Note the elevation difference between the northern and southern hemispheres. The Tharsis volcano-tectonic province is centered near the equator in the longitude range 220o E to 300o E and contains the vast east-west trending Valles Marineris canyon system and several major volcanic shields including Olympus Mons (18o N, 225o E), Alba Patera (42o N, 252o E), Ascraeus Mons (12o N, 248o E), Pavonis Mons (0o, 247o E), and Arsia Mons (9o S, 239o E). Regions and structures discussed in the text include Solis Planum (25o S, 270o E), Lunae Planum (10o N, 290o E), and Claritas Fossae (30o S, 255o E). Major impact basins include Hellas (45o S, 70o E), Argyre (50o S, 320o E), Isidis (12o N, 88o E), and Utopia (45o N, 110o E). This analysis uses an areocentric coordinate convention with east longitude positive.

  16. Topography driven conceptual modelling (Invited)

    NASA Astrophysics Data System (ADS)

    Savenije, H.

    2009-12-01

    Heterogeneity and complexity of hydrological processes offer substantial challenges to the hydrological modeller. Some hydrologists try to tackle this problem by introducing more and more detail in their models, or by setting-up more and more complex models starting from basic principles at the smallest possible level. As we know, this reductionist approach leads to ever higher levels of equifinality and predictive uncertainty. On the other hand, simple, lumped and parsimonious models may be too simple to be realistic or representative of the dominant hydrological processes. In this paper, a new model approach is proposed that tries to find the middle way between complex distributed and simple lumped modelling approaches. It addresses an aspect often overlooked in model uncertainty assessment: the structural errors made by conceptual misrepresentation. It uses a flexible model architecture based on a classification system that is topography driven. Catchments are divided into different conceptual model classes, which are subsequently modelled with parsimonious conceptual models. The approach is process based, but not physically based in the traditional sense. Instead, it is based on a conceptual representation of the dominant physical processes in certain key elements of the landscape.

  17. Improved Lunar Control and Topography

    NASA Astrophysics Data System (ADS)

    Archinal, B. A.; Rosiek, M. R.; Kirk, R. L.; Redding, B. L.

    2005-08-01

    We are completing the Unified Lunar Control Network (ULCN) 2005, an update and combination of the ULCN (Davies and Colvin 1994) and the Clementine LCN (CLCN) (unpublished) on which USGS Clementine mosaics are based. The new network should correct for large ( 7 km average to > 15 km) errors in the CLCN by constraining ULCN positions and camera angles, and by solving for radii at all points rather than assuming a sphere. The result will be a 3-D network, including a globally complete and consistent topographic model for the Moon tied directly to horizontal control. The estimated horizontal accuracy of our current solution ranges from 1 km in the areas of ULCN points to 3 km outside these areas. The current ULCN has a vertical accuracy of a few hundred meters when compared to Clementine lidar. The true accuracy may be higher, due to interpolation and lidar positional errors involved in the comparison. The final version should be available at the time of the DPS. Our current solution includes 546,142 image measures of 272,949 points and 43,866 Clementine (mostly 750-nm) images. We will report the results in a peer-reviewed article and distribute the network data from our website (http://astrogeology.usgs.gov/Projects/ControlNetworks/). This solution will be useful for scientific study of lunar morphology and basins; and for operational uses in selecting and targeting landing sites and evaluating landing hazards due to topography. A future solution will include Lunar Orbiter, Mariner 10, and Galileo data. Additionally, it will serve as the basis for solutions with data from upcoming missions, thus placing all data in one consistent coordinate system. We acknowledge the initiation of this work by T. Colvin and (the late) M. Davies at RAND, and funding from the NASA PG&G program.

  18. Renormalisation of Global Mantle Dynamic Topography Predictions using Residual Topography Measurements for "Normal" Ocean Crust

    NASA Astrophysics Data System (ADS)

    Cowie, Fergus; Kusznir, Nick; Cowie, Leanne

    2015-04-01

    The best constraint on model predictions of present day mantle dynamic topography are measurements of residual topography. Residual topography is calculated by removing the isostatic effects of bathymetry, sediments, ice, crustal thickness variation and lithosphere thermal anomalies from the observed topography. Comparison of global model predictions of mantle dynamic topography with global compilations of residual topography, while showing a broadly similar pattern at long wavelengths, differ substantially in amplitude. A strong contribution to the present day surface topographic signal arises from crustal thickness variation. As a consequence it is difficult to accurately determine residual topography for continental crust and for oceanic regions with substantially thicker than average oceanic crust (e.g. oceanic crust adjacent to volcanic rifted margins, oceanic plume tracks, volcanic plateaux, micro-continents). Residual topography is best measured on ocean crust of "normal" oceanic thickness. We use global mapping of crustal thickness using gravity inversion to identify crust with thicknesses greater than that of "normal" oceanic crust in order than we can eliminate the less accurate measurements of residual topography for these thicker crustal regions. Comparison of model predicted mantle dynamic topography with residual topography measurements for the remaining regions of thinner "normal" oceanic crust shows an improved correlation but with a dynamic topography showing a positive bias with respect to residual topography and a greater amplitude. We use residual topography measurements for "normal" oceanic crust to downward shift (by approximately 600 m) and rescale (by 0.6) predicted global mantle dynamic topography. We present maps of the renormalised model predictions of global mantle topography from Steinberger (2007) and Flament et al. (2013). One consequence of renormalization is to reduce the amplitude of predicted mantle dynamic topographic uplift in the Pacific. The gravity inversion methodology includes a correction for the elevated geothermal gradient of oceanic and rifted continental margin lithosphere and sediment thickness. Caveats on this methodology are (i) that the gravity inversion methodology used to determine crustal thickness for screening out thick crust is itself dependent on mantle dynamic topography (but fortunately only weakly so) and (ii) that the renormalization procedure is biased towards oceanic regions.

  19. Enhanced Characterization of Niobium Surface Topography

    SciTech Connect

    Chen Xu, Hui Tian, Charles Reece, Michael Kelley

    2011-12-01

    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.

  20. Corneal topography measurements for biometric applications

    NASA Astrophysics Data System (ADS)

    Lewis, Nathan D.

    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.

  1. Electronic Cigarette Topography in the Natural Environment

    PubMed Central

    Morabito, P. N.; Roundtree, K. A.

    2015-01-01

    This paper presents the results of a clinical, observational, descriptive study to quantify the use patterns of electronic cigarette users in their natural environment. Previously published work regarding puff topography has been widely indirect in nature, and qualitative rather than quantitative, with the exception of three studies conducted in a laboratory environment for limited amounts of time. The current study quantifies the variation in puffing behaviors among users as well as the variation for a given user throughout the course of a day. Puff topography characteristics computed for each puffing session by each subject include the number of subject puffs per puffing session, the mean puff duration per session, the mean puff flow rate per session, the mean puff volume per session, and the cumulative puff volume per session. The same puff topography characteristics are computed across all puffing sessions by each single subject and across all subjects in the study cohort. Results indicate significant inter-subject variability with regard to puffing topography, suggesting that a range of representative puffing topography patterns should be used to drive machine-puffed electronic cigarette aerosol evaluation systems. PMID:26053075

  2. Topography Restoration of Historic City Research

    NASA Astrophysics Data System (ADS)

    ho, L. Sung; soo, H. Dong

    2015-08-01

    The preservation of historic cities requires a balance between conservation and development because the urban structures of the old and new city are interwoven on same space. Existing restoration plans rely on old records and excavation reports and are based on the present topography. However, historic cities have undergone significant natural and anthropogenic topographic changes such as alluvial sediment accumulation and uneven terrain construction. Therefore, considering only the present topography is misleading. Thus, to understand a historic city's structure more appropriately, it is necessary to comprehend the ancient geographic environment. This study provides an analysis and GIS visualization of the ancient topography of a historic city, Sabi capital city of the Baekje Dynasty, which collapsed 1,500 years ago.

  3. Retrodicting the late Cenozoic dynamic topography

    NASA Astrophysics Data System (ADS)

    Moucha, Robert; Forte, Alessandro; Glisovic, Petar; Rowley, David; Mitrovica, Jerry; Simmons, Nathan; Grand, Stephen

    2010-05-01

    We reconstruct the global late Cenozoic dynamic topography by carrying out backward-in-time mantle flow simulations starting with present-day heterogeneity derived from a high-resolution joint seismic-geodynamic tomography model (Simmons et al., 2009). Herein, we will explore the associated uncertainties and geological implications of our topography retrodictions. Heuristic estimates of uncertainties are obtained using two different approaches to backward mantle convection -- the backward advection method and the quasi-reversible convection method. Comparison of these two methods exposes the relative importance of diffusion in our retrodictions. Additional contributions to our uncertainties that originate from the starting models of mantle heterogeneity and rheology are also investigated. We further assess the validity of our models of topography evolution with the geological record. In particular, we focus on dynamic surface features such as the Colorado Plateau in the southwestern US, the Angolan margin and Congo-Zaire basins in Africa.

  4. Topography of Earth's Inner Core Boundary

    NASA Astrophysics Data System (ADS)

    Cormier, V. F.; Zheng, Y.; Hernlund, J. W.

    2011-12-01

    Lateral variations in the structure and crystallization of the inner core will likely be associated with lateral variations in the topography of its boundary. Depending on liquid fraction and the ratio of solid over liquid viscosity, the process of compaction of solids and expulsion of fluids at the solidifying boundary can be dynamically unstable, resulting in small-scale corrugations of the boundary of 0.1 to 5 km height with a horizontal scale on the order of 1 to 10 km. Evidence of such ICB topography has been inferred from waveforms of PKiKP doublets (1). An additional observation consistent ICB topography includes the seismic wave diffracted around the top of the inner core (PKP-Cdiff), whose travel time agrees with that predicted by the AK135 Earth model, but whose amplitude decays more rapidly into the inner core shadow than is predicted by AK135 (2). These observations are modeled by synthesizing seismic body waves with a pseudospectral method (3) having a densified grid in the vicinity of a rough ICB. Validation of the forward modeling includes a comparison of results obtained with a boundary element method. Modeled spectra of ICB topography are used to constrain the parameters and processes that produce the topography. These include compaction length (assuming freezing upward from below), the structure of precipitated piles (assuming metallic snow falling from above), the sedimentary processes due to flow in the overlying F-layer of the outer core, and the relaxation of topography from viscous deformation of the inner core. 1. Cao, A., Y. Masson, and B. Romanowicz, PNAS, 104, 31-35, 2007. 2. Zou, Z., K. Koper, and V.F. Cormier, J. Geophys. Res., 113, 2008. doi: 10.1029/2007JB005316. 3. Furumura T., B.L.N. Kennett, and M. Furumura, Geophys. J. Int., 135, 845--860, 1998.

  5. Structures of lee waves over combined topography

    NASA Astrophysics Data System (ADS)

    Makarenko, Nikolay; Maltseva, Janna; Cherevko, Alexander

    2015-10-01

    The problem on non-homogeneous shear flows over rough terrain is considered semi-analytically. A non-linear model of stratified flow over combined obstacle is constructed in the small amplitude limit for the topography. The method uses a Fourier series in modal decomposition of waves caused by a localized multi-bump obstacle modeling a mountain range. The focus of attention is on the stationary wave patterns formed directly above the mountain range. Wave solutions corresponding to topography with a finite number of peaks are calculated. These solutions predict rigorously the splitting of a near-field flow into separate wave zones having different spatial scales.

  6. Effects of patterned topography on biofilm formation

    NASA Astrophysics Data System (ADS)

    Vasudevan, Ravikumar

    2011-12-01

    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)

  7. OPC verification considering CMP induced topography

    NASA Astrophysics Data System (ADS)

    Kuncha, Rakesh Kumar; Narayana Samy, Aravind; Katakamsetty, Ushasree

    2015-09-01

    OPC Verification is important to identify the critical wafer hotspots prior to mask fabrication. It helps to identify process limiting structures and possible yield limiters. These hotspots are also used by litho engineers to set up process conditions upfront. OPC Verification generally involves verification done at nominal and process window conditions. The process window conditions take into consideration typical process variations for lithography. In this standard flow, the post CMP topography variation was also lumped into these process variations via focus. But in current technologies especially in higher metal layers, CMP induced topography variation has become a major contributor to limit the overall process window. This results in different best focus for structures with different topography. This gives rises to requirement of OPC Verification flow taking into account these location-specific variations in order to know if the mask data can be used or not. This paper proposes a method to incorporate the topography induced focus shift into the OPC Verification flow. OPC Verification checks are performed at the new nominal and Process window conditions to identify the real hotspots seen on wafer. Results are shown where the highlighted hotspots with the proposed new flow correlate better with wafer results. Runtime was also taken into consideration when the flow was developed. Experiments on various products show better accuracy with minimal runtime impact.

  8. Sea bottom topography imaging with SAR

    NASA Technical Reports Server (NTRS)

    Vanderkooij, M. W. A.; Wensink, G. J.; Vogelzang, J.

    1992-01-01

    It is well known that under favorable meteorological and hydrodynamical conditions the bottom topography of shallow seas can be mapped with airborne or spaceborne imaging radar. This phenomenon was observed for the first time in 1969 by de Loor and co-workers in Q-band Side Looking Airborne Radar (SLAR) imagery of sandwaves in the North Sea. It is now generally accepted that the imaging mechanism consists of three steps: (1) interaction between (tidal) current and bottom topography causes spatial modulations in the surface current velocity; (2) modulations in the surface current velocity give rise to variations in the spectrum of wind-generated waves, as described by the action balance equation; and (3) variations in the wave spectrum show up as intensity modulations in radar imagery. In order to predict radar backscatter modulations caused by sandwaves, an imaging model, covering the three steps, was developed by the Dutch Sea Bottom Topography Group. This model and some model results will be shown. On 16 Aug. 1989 an experiment was performed with the polarimetric P-, L-, and C-band synthetic aperture radar (SAR) of NASA/JPL. One scene was recorded in SAR mode. On 12 Jul. 1991 another three scenes were recorded, of which one was in the ATI-mode (Along-Track Interferometer). These experiments took place in the test area of the Sea Bottom Topography Group, 30 km off the Dutch coast, where the bottom topography is dominated by sand waves. In-situ data were gathered by a ship in the test area and on 'Measuring Platform Noordwijk', 20 km from the center of the test area. The radar images made during the experiment were compared with digitized maps of the bottom. Furthermore, the profiles of radar backscatter modulation were compared with the results of the model. During the workshop some preliminary results of the ATI measurements will be shown.

  9. Global relationship between oceanic geoid and topography

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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.

  10. Topography over South America from ERS altimetry

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    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.

  11. Diffraction imaging (topography) with monochromatic synchrotron radiation

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    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.

  12. ATM Coastal Topography-Mississippi, 2001

    USGS Publications Warehouse

    Nayegandhi, Amar; Yates, Xan; Brock, John C.; Sallenger, A.H.; Klipp, Emily S.; Wright, C. Wayne

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of lidar-derived first-surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Mississippi coastline, from Lakeshore to Petit Bois Island, acquired September 9-10, 2001. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative scanning lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM 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 presurvey 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 used routinely to create maps that represent submerged or first-surface topography.

  13. ATM Coastal Topography-Alabama 2001

    USGS Publications Warehouse

    Nayegandhi, Amar; Yates, Xan; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Klipp, Emily S.; Wright, C. Wayne

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Alabama coastline, acquired October 3-4, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface, and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM 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.

  14. Topography measurement of specular and diffuse surfaces

    NASA Astrophysics Data System (ADS)

    Serrano García, David Ignacio; Martínez García, Amalia; Rayas-Alvarez, Juan Antonio

    2010-08-01

    We measured the topography of lens by using a technique of diffuse reflection (fringe projection technique) and by a method based on specular reflection technique (similar to Placido disk system). The obtained results with both techniques are compared with those obtained with a spherometer. The retrieval of the three-dimensional shape of the lens is an issue of great interest for wide medical application, particularly in ophthalmology.

  15. Wholemount immunohistochemistry for revealing complex brain topography.

    PubMed

    White, Joshua J; Reeber, Stacey L; Hawkes, Richard; Sillitoe, Roy V

    2012-01-01

    The repeated and well-understood cellular architecture of the cerebellum make it an ideal model system for exploring brain topography. Underlying its relatively uniform cytoarchitecture is a complex array of parasagittal domains of gene and protein expression. The molecular compartmentalization of the cerebellum is mirrored by the anatomical and functional organization of afferent fibers. To fully appreciate the complexity of cerebellar organization we previously refined a wholemount staining approach for high throughput analysis of patterning defects in the mouse cerebellum. This protocol describes in detail the reagents, tools, and practical steps that are useful to successfully reveal protein expression patterns in the adult mouse cerebellum by using wholemount immunostaining. The steps highlighted here demonstrate the utility of this method using the expression of zebrinII/aldolaseC as an example of how the fine topography of the brain can be revealed in its native three-dimensional conformation. Also described are adaptations to the protocol that allow for the visualization of protein expression in afferent projections and large cerebella for comparative studies of molecular topography. To illustrate these applications, data from afferent staining of the rat cerebellum are included. PMID:22508094

  16. Evolution of Neogene Dynamic Topography in Africa

    NASA Astrophysics Data System (ADS)

    Paul, Jonathan; Roberts, Gareth; White, Nicky

    2013-04-01

    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.

  17. EAARL topography: Gateway National Recreation Area

    USGS Publications Warehouse

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

    2007-01-01

    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.

  18. Neurofunctional topography of the human hippocampus.

    PubMed

    Robinson, Jennifer L; Barron, Daniel S; Kirby, Lauren A J; Bottenhorn, Katherine L; Hill, Ashley C; Murphy, Jerry E; Katz, Jeffrey S; Salibi, Nouha; Eickhoff, Simon B; Fox, Peter T

    2015-12-01

    Much of what was assumed about the functional topography of the hippocampus was derived from a single case study over half a century ago. Given advances in the imaging sciences, a new era of discovery is underway, with potential to transform the understanding of healthy processing as well as the ability to treat disorders. Coactivation-based parcellation, a meta-analytic approach, and ultra-high field, high-resolution functional and structural neuroimaging to characterize the neurofunctional topography of the hippocampus was employed. Data revealed strong support for an evolutionarily preserved topography along the long-axis. Specifically, the left hippocampus was segmented into three distinct clusters: an emotional processing cluster supported by structural and functional connectivity to the amygdala and parahippocampal gyrus, a cognitive operations cluster, with functional connectivity to the anterior cingulate and inferior frontal gyrus, and a posterior perceptual cluster with distinct structural connectivity patterns to the occipital lobe coupled with functional connectivity to the precuneus and angular gyrus. The right hippocampal segmentation was more ambiguous, with plausible 2- and 5-cluster solutions. Segmentations shared connectivity with brain regions known to support the correlated processes. This represented the first neurofunctional topographic model of the hippocampus using a robust, bias-free, multimodal approach. Hum Brain Mapp 36:5018-5037, 2015. 2015 Wiley Periodicals, Inc. PMID:26350954

  19. EAARL topography: George Washington Birthplace National Monument

    USGS Publications Warehouse

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

    2007-01-01

    This Web site contains Lidar-derived topography (first return and bare earth) maps and GIS files for George Washington Birthplace National Monument in Virginia. 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), Northeast Coastal and Barrier 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 coastal resource managers.

  20. EAARL Topography-Padre Island National Seashore

    USGS Publications Warehouse

    Brock, John C.; Wright, C. Wayne; Nayegandhi, Amar; Patterson, Matt; Wilson, Iris; Travers, Laurinda J.

    2007-01-01

    This Web site contains 116 Lidar-derived bare earth topography maps and GIS files for Padre Island National Seashore-Texas. These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Florida Integrated Science Center (FISC) St. Petersburg, Florida, the National Park Service (NPS) Gulf Coast 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.

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

    PubMed

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

    2005-10-15

    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. PMID:16252765

  2. OpenTopography: Enabling Online Access to High-Resolution Lidar Topography Data and Processing Tools

    NASA Astrophysics Data System (ADS)

    Crosby, Christopher; Nandigam, Viswanath; Baru, Chaitan; Arrowsmith, J. Ramon

    2013-04-01

    High-resolution topography data acquired with lidar (light detection and ranging) technology are revolutionizing the way we study the Earth's surface and overlying vegetation. These data, collected from airborne, tripod, or mobile-mounted scanners have emerged as a fundamental tool for research on topics ranging from earthquake hazards to hillslope processes. Lidar data provide a digital representation of the earth's surface at a resolution sufficient to appropriately capture the processes that contribute to landscape evolution. The U.S. National Science Foundation-funded OpenTopography Facility (http://www.opentopography.org) is a web-based system designed to democratize access to earth science-oriented lidar topography data. OpenTopography provides free, online access to lidar data in a number of forms, including the raw point cloud and associated geospatial-processing tools for customized analysis. The point cloud data are co-located with on-demand processing tools to generate digital elevation models, and derived products and visualizations which allow users to quickly access data in a format appropriate for their scientific application. The OpenTopography system is built using a service-oriented architecture (SOA) that leverages cyberinfrastructure resources at the San Diego Supercomputer Center at the University of California San Diego to allow users, regardless of expertise level, to access these massive lidar datasets and derived products for use in research and teaching. OpenTopography hosts over 500 billion lidar returns covering 85,000 km2. These data are all in the public domain and are provided by a variety of partners under joint agreements and memoranda of understanding with OpenTopography. Partners include national facilities such as the NSF-funded National Center for Airborne Lidar Mapping (NCALM), as well as non-governmental organizations and local, state, and federal agencies. OpenTopography has become a hub for high-resolution topography resources. Datasets hosted by other organizations, as well as lidar-specific software, can be registered into the OpenTopography catalog, providing users a "one-stop shop" for such information. With several thousand active users, OpenTopography is an excellent example of a mature Spatial Data Infrastructure system that is enabling access to challenging data for research, education and outreach. Ongoing OpenTopography design and development work includes the archive and publication of datasets using digital object identifiers (DOIs); creation of a more flexible and scalable high-performance environment for processing of large datasets; expanded support for satellite and terrestrial lidar; and creation of a "pluggable" infrastructure for third-party programs and algorithms. OpenTopography has successfully created a facility for sharing lidar data. In the project's next phase, we are working to enable equally easy and successful sharing of services for processing and analysis of these data.

  3. Seismic waveform sensitivity to global boundary topography

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

    We investigate the implications of lateral variations in the topography of global seismic discontinuities, in the framework of high-resolution forward modelling and seismic imaging. We run 3-D wave-propagation simulations accurate at periods of 10 s and longer, with Earth models including core-mantle boundary topography anomalies of 1000 km spatial wavelength and up to 10 km height. We obtain very different waveform signatures for PcP (reflected) and Pdiff (diffracted) phases, supporting the theoretical expectation that the latter are sensitive primarily to large-scale structure, whereas the former only to small scale, where large and small are relative to the frequency. PcP at 10 s seems to be well suited to map such a small-scale perturbation, whereas Pdiff at the same frequency carries faint signatures that do not allow any tomographic reconstruction. Only at higher frequency, the signature becomes stronger. We present a new algorithm to compute sensitivity kernels relating seismic traveltimes (measured by cross-correlation of observed and theoretical seismograms) to the topography of seismic discontinuities at any depth in the Earth using full 3-D wave propagation. Calculation of accurate finite-frequency sensitivity kernels is notoriously expensive, but we reduce computational costs drastically by limiting ourselves to spherically symmetric reference models, and exploiting the axial symmetry of the resulting propagating wavefield that collapses to a 2-D numerical domain. We compute and analyse a suite of kernels for upper and lower mantle discontinuities that can be used for finite-frequency waveform inversion. The PcP and Pdiff sensitivity footprints are in good agreement with the result obtained cross-correlating perturbed and unperturbed seismogram, validating our approach against full 3-D modelling to invert for such structures.

  4. Topography Influences Adherent Cell Regulation of Osteoclastogenesis.

    PubMed

    Nagasawa, M; Cooper, L F; Ogino, Y; Mendonca, D; Liang, R; Yang, S; Mendonca, G; Uoshima, K

    2016-03-01

    The importance of osteoclast-mediated bone resorption in the process of osseointegration has not been widely considered. In this study, cell culture was used to investigate the hypothesis that the function of implant-adherent bone marrow stromal cells (BMSCs) in osteoclastogenesis is influenced by surface topography. BMSCs isolated from femur and tibia of Sprague-Dawley rats were seeded onto 3 types of titanium surfaces (smooth, micro, and nano) and a control surface (tissue culture plastic) with or without osteogenic supplements. After 3 to 14 d, conditioned medium (CM) was collected. Subsequently, rat bone marrow-derived macrophages (BMMs) were cultured in media supplemented with soluble receptor activator of NF-?B ligand (RANKL) and macrophage colony-stimulating factor (M-CSF) as well as BMSC CM from each of the 4 surfaces. Gene expression levels of soluble RANKL, osteoprotegerin, tumor necrosis factor ?, and M-CSF in cultured BMSCs at different time points were measured by real-time polymerase chain reaction. The number of differentiated osteoclastic cells was determined after tartrate-resistant acid phosphatase staining. Analysis of variance and t test were used for statistical analysis. The expression of prominent osteoclast-promoting factors tumor necrosis factor ? and M-CSF was increased by BMSCs cultured on both micro- and nanoscale titanium topographies (P < 0.01). BMSC CM contained a heat-labile factor that increased BMMs osteoclastogenesis. CM from both micro- and nanoscale surface-adherent BMSCs increased the osteoclast number (P < 0.01). Difference in surface topography altered BMSC phenotype and influenced BMM osteoclastogenesis. Local signaling by implant-adherent cells at the implant-bone interface may indirectly control osteoclastogenesis and bone accrual around endosseous implants. PMID:26553885

  5. Macromolecular Topography Leaps into the Digital Age

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

    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.

  6. Carbon contamination topography analysis of EUV masks

    SciTech Connect

    Fan, Y.-J.; Yankulin, L.; Thomas, P.; Mbanaso, C.; Antohe, A.; Garg, R.; Wang, Y.; Murray, T.; Wuest, A.; Goodwin, F.; Huh, S.; Cordes, A.; Naulleau, P.; Goldberg, K. A.; Mochi, I.; Gullikson, E.; Denbeaux, G.

    2010-03-12

    The impact of carbon contamination on extreme ultraviolet (EUV) masks is significant due to throughput loss and potential effects on imaging performance. Current carbon contamination research primarily focuses on the lifetime of the multilayer surfaces, determined by reflectivity loss and reduced throughput in EUV exposure tools. However, contamination on patterned EUV masks can cause additional effects on absorbing features and the printed images, as well as impacting the efficiency of cleaning process. In this work, several different techniques were used to determine possible contamination topography. Lithographic simulations were also performed and the results compared with the experimental data.

  7. EAARL Coastal Topography - Sandy Hook 2007

    USGS Publications Warehouse

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

    2008-01-01

    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.

  8. Welcome to Surface Topography: Metrology and Properties

    NASA Astrophysics Data System (ADS)

    Leach, Richard

    2013-11-01

    I am delighted to welcome readers to this inaugural issue of Surface Topography: Metrology and Properties (STMP). In these days of citation indexes and academic reviews, it is a tough, and maybe a brave, job to start a new journal. But the subject area has never been more active and we are seeing genuine breakthroughs in the use of surfaces to control functional performance. Most manufactured parts rely on some form of control of their surface characteristics. The surface is usually defined as that feature on a component or device, which interacts with either the environment in which it is housed (or in which the device operates), or with another surface. The surface topography and material characteristics of a part can affect how fluids interact with it, how the part looks and feels and how two bearing parts will slide together. The need to control, and hence measure, surface features is becoming increasingly important as we move into a miniaturized world. Surface features can become the dominant functional features of a part and may become large in comparison to the overall size of an object. Research into surface texture measurement and characterization has been carried out for over a century and is now more active than ever, especially as new areal surface texture specification standards begin to be introduced. The range of disciplines for which the function of a surface relates to its topography is very diverse; from metal sheet manufacturing to art restoration, from plastic electronics to forensics. Until now, there has been no obvious publishing venue to bring together all these applications with the underlying research and theory, or to unite those working in academia with engineering and industry. Hence the creation of Surface Topography: Metrology and Properties . STMP will publish the best work being done across this broad discipline in one journal, helping researchers to share common themes and highlighting and promoting the extraordinary benefits this field yields across an array of applications in the modern world. To this end, we have gathered leading experts from across our scope to form our inaugural editorial board. Their broad subject knowledge and experience will help to guide the journal and ensure we meet our goal of high-quality research, published quickly, across the breadth of the subject. We are committed to providing a rapid and yet rigorous peer review process. As a launch promotion, all STMP's published content will be free to readers during 2013. The editorial board and I hope you will be as excited by the possibilities of this new journal as we are, and that you will choose to both submit your research and read STMP in the months and years to come. We look forward to reading your papers!

  9. Support of long-wavelength topography on Mercury inferred from MESSENGER measurements of gravity and topography

    NASA Astrophysics Data System (ADS)

    James, Peter B.; Zuber, Maria T.; Phillips, Roger J.; Solomon, Sean C.

    2015-02-01

    To explore the mechanisms of support of surface topography on Mercury, we have determined the admittances and correlations of topography and gravity in Mercury's northern hemisphere from measurements obtained by NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. These admittances and correlations can be interpreted in the context of a number of theoretical scenarios, including flexural loading and dynamic flow. We find that long-wavelength (spherical harmonic degree l < 15) surface topography on Mercury is primarily supported through a combination of crustal thickness variations and deep mass anomalies. The deep mass anomalies may be interpreted either as lateral variations in mantle density or as relief on compositional interfaces. Domical topographic swells are associated with high admittances and are compensated at 300-400 km depth in the lower reaches of Mercury's mantle. Quasi-linear topographic rises are primarily associated with shallow crustal compensation and are weakly correlated with positive mass anomalies in the mantle. The center of the Caloris basin features some of the thinnest crust on the planet, and the basin is underlain by a large negative mass anomaly. We also explore models of dynamic flow in the presence of compositional stratification above the liquid core. If there is substantial compositional stratification in Mercury's solid outer shell, relaxation of perturbed compositional interfaces may be capable of creating and sustaining long-wavelength topography.

  10. EAARL Topography-Colonial National Historical Park

    USGS Publications Warehouse

    Brock, John C.; Wright, C. Wayne; Nayegandhi, Amar; Stevens, Sara; Travers, Laurinda J.

    2008-01-01

    These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, Florida Integrated Science Center (FISC) St. Petersburg, the National Park Service (NPS) Inventory and Monitoring Program, Northeast Coastal and Barrier Network, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs, barrier islands, and various nearshore coastal environments 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 coastal resource managers.

  11. Uncertainty in measurement of surface topography

    NASA Astrophysics Data System (ADS)

    Haitjema, Han

    2015-09-01

    The 2.5-dimensional (2.5D) roughness parameters were standardized in 2012. With their increasing use in science and industry, the request for traceability and uncertainty evaluation for these parameters follows logically. This paper gives an overview of the problems and possibilities that appear when uncertainties have to be associated with values that are derived from a measured surface topography, such as the Ra-value of a periodic specimen, the RSm value of a type-D standard, and the Sa-value of a single cutoff length of a type D standard. It is shown that straightforward implementation of the methods described in the Guide to the Expression of Uncertainty in Measurement (GUM) leads to impossible and impracticable equations because of the correlations between some millions of measurement points. A practical solution is found by considering the main aspects of uncertainty, as these are given in the recent ISO 25178 standards series, and applying these to a measured surface topography as a whole.

  12. Analysis Of Scoliosis By Back Shape Topography

    NASA Astrophysics Data System (ADS)

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

    1983-07-01

    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.

  13. Hydrothermal circulation in fault slots with topography

    NASA Astrophysics Data System (ADS)

    Titarenko, Sofya; McCaig, Andrew

    2014-05-01

    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.

  14. EAARL Coastal Topography - Northern Gulf of Mexico

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Sallenger, Abby; Wright, C. Wayne; Travers, Laurinda J.; Lebonitte, James

    2008-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived coastal topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. One objective of this research is to create techniques to survey areas for the purposes of geomorphic change studies following major storm events. The USGS Coastal and Marine Geology Program's National Assessment of Coastal Change Hazards project is a multi-year undertaking to identify and quantify the vulnerability of U.S. shorelines to coastal change hazards such as effects of severe storms, sea-level rise, and shoreline erosion and retreat. Airborne Lidar surveys conducted during periods of calm weather are compared to surveys collected following extreme storms in order to quantify the resulting coastal change. Other applications of high-resolution topography include habitat mapping, ecological monitoring, volumetric change detection, and event assessment. The purpose of this project is to provide highly detailed and accurate datasets of the northern Gulf of Mexico coastal areas, acquired on September 19, 2004, immediately following Hurricane Ivan. 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 Airborne Advanced 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 RGB (red-green-blue) 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 sub-meter 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 on September 19, 2004. The survey resulted in the acquisition of 3.2 gigabytes of data. The data were 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 sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of 'last return' elevations.

  15. Origin of bending in uncoated microcantilever - Surface topography?

    SciTech Connect

    Lakshmoji, K.; Prabakar, K.; Tripura Sundari, S. Jayapandian, J.; Tyagi, A. K.; Sundar, C. S.

    2014-01-27

    We provide direct experimental evidence to show that difference in surface topography on opposite sides of an uncoated microcantilever induces bending, upon exposure to water molecules. Examination on opposite sides of the microcantilever by atomic force microscopy reveals the presence of localized surface features on one side, which renders the induced stress non-uniform. Further, the root mean square inclination angle characterizing the surface topography shows a difference of 73° between the opposite sides. The absence of deflection in another uncoated microcantilever having similar surface topography confirms that in former microcantilever bending is indeed induced by differences in surface topography.

  16. Mariner ultraviolet spectrometer: topography and polar cap.

    PubMed

    Barth, C A; Hord, C W

    1971-07-16

    Mars, the red planet, reflects sunlight in the ultraviolet, but it is the atmosphere, not the surface, that is responsible for the reflected light. Even though there are atmospheric scatterers in addition to the molecular scatterers, it is possible to relate the intensity of the scattered radiation with the atmospheric pressure. The variation of pressure over the planet reveals the topography to vary over 7 kilometers in height and to be correlated with visible features. The carbon dioxide polar cap, in addition to being a cold trap for volatile gases in the atmosphere, may alsobe a very efficient adsorption trap for nonvolatiles. This last property may make the cap a repository for gases produced by geological or biological activity (15). PMID:17741407

  17. Gravity and topography. [of planet Mars

    NASA Technical Reports Server (NTRS)

    Esposito, P. B.; Banerdt, W. B.; Lindal, G. F.; Sjogren, W. L.; Slade, M. A.; Bills, B. G.; Smith, D. E.; Balmino, G.

    1992-01-01

    The paper summarizes the fundamental gravity field constants for Mars and a brief historical review of early determinations and current-day accurate estimates. These include the planetary gravitational constant, global figure, dynamical oblateness, mean density, and rotational period. Topographic results from data acquired from the 1967 opposition to the most recent, 1988, opposition are presented. Both global and selected local topographic variations and features are discussed. The inertia tensor and the nonhydrostatic component of Mars are examined in detail. The dimensionless moment of inertia about the rotational axis is 0.4 for a body of uniform density and 0.37621 if Mars were in hydrostatic equilibrium. By comparing models of both gravity and topography, inferences are made about the degree and depth of compensation in the interior and stresses in the lithosphere.

  18. EAARL topography: Dry Tortugas National Park

    USGS Publications Warehouse

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

    2008-01-01

    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, ad 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.

  19. Architecture and development of olivocerebellar circuit topography

    PubMed Central

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

    2013-01-01

    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

  20. Mean Dynamic Topography of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

    Farrell, Sinead Louise; Mcadoo, David C.; Laxon, Seymour W.; Zwally, H. Jay; Yi, Donghui; Ridout, Andy; Giles, Katherine

    2012-01-01

    ICESat and Envisat altimetry data provide measurements of the instantaneous sea surface height (SSH) across the Arctic Ocean, using lead and open water elevation within the sea ice pack. First, these data were used to derive two independent mean sea surface (MSS) models by stacking and averaging along-track SSH profiles gathered between 2003 and 2009. The ICESat and Envisat MSS data were combined to construct the high-resolution ICEn MSS. Second, we estimate the 5.5-year mean dynamic topography (MDT) of the Arctic Ocean by differencing the ICEn MSS with the new GOCO02S geoid model, derived from GRACE and GOCE gravity. Using these satellite-only data we map the major features of Arctic Ocean dynamical height that are consistent with in situ observations, including the topographical highs and lows of the Beaufort and Greenland Gyres, respectively. Smaller-scale MDT structures remain largely unresolved due to uncertainties in the geoid at short wavelengths.

  1. Assimilation of altimeter topography into oceanic models

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

    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.

  2. Rotating barotropic flow over finite isolated topography

    NASA Astrophysics Data System (ADS)

    Bannon, P. R.

    1980-11-01

    A study is presented of the flow of a rotating incompressible fluid over isolated topography whose nondimensional height (i.e., topographic height divided by the mean fluid depth) is large compared with the Rossby number. Attention is restricted to the flow which is sufficiently shallow that the free-surface equations provide an adequate description. The flow is forced laterally by a specified upstream inflow and by a prescribed surface stress; dissipation is incorporated using a Rayleigh friction acting antiparallel to the flow. Steady state solutions for uniform inflow on an f-plane are found for linear viscous flow, quasi-geostrophic flow with and without friction, and inviscid flow with and without a rigid lid.

  3. Absorber topography dependence of phase edge effects

    NASA Astrophysics Data System (ADS)

    Shanker, Aamod; Sczyrba, Martin; Connolly, Brid; Waller, Laura; Neureuther, Andy

    2015-10-01

    Mask topography contributes to phase at the wafer plane, even for OMOG binary masks currently in use at the 22nm node in deep UV (193nm) lithography. Here, numerical experiments with rigorous FDTD simulation are used to study the impact of mask 3D effects on aerial imaging, by varying the height of the absorber stack and its sidewall angle. Using a thin mask boundary layer model to fit to rigorous simulations it is seen that increasing the absorber thickness, and hence the phase through the middle of a feature (bulk phase) monotonically changes the wafer-plane phase. Absorber height also influences best focus, revealed by an up/down shift in the Bossung plot (linewidth vs. defocus). Bossung plot tilt, however, responsible for process window variability at the wafer, is insensitive to changes in the absorber height (and hence also the bulk phase). It is seen to depend instead on EM edge diffraction from the thick mask edge (edge phase), but stays constant for variations in mask thickness within a 10% range. Both bulk phase and edge phase are also independent of sidewall angle fluctuation, which is seen to linearly affect the CD at the wafer, but does not alter wafer phase or the defocus process window. Notably, as mask topography varies, the effect of edge phase can be replicated by a thin mask model with 8nm wide boundary layers, irrespective of absorber height or sidewall angle. The conclusions are validated with measurements on phase shifting masks having different topographic parameters, confirming the strong dependence of phase variations at the wafer on bulk phase of the mask absorber.

  4. Bedrock topography beneath the Red Lake peatlands

    SciTech Connect

    Miller, P.; Shaw, G.H. . Geology Dept.); Glaser, P. . Limnological Research Center); Siegel, D. . Dept. of Geology)

    1992-01-01

    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.

  5. An Assessment of Topography Measurements on Europa

    NASA Astrophysics Data System (ADS)

    Greenberg, Richard; Hurford, T.; Foley, M.

    2006-09-01

    Many small patches of chaotic terrain on Europa appear to be bulged upward, giving qualitative impressions that chaos might represent "cryovolcanic" and/or convective upwelling. The same bulged appearance is explained by the oceanic melt-through model, as simply the topography expected after refreezing and buoyant equilibrium. Greenberg et al. suggested an observational test to discriminate between these models, based on whether the up-bulged chaos is higher than the typical tectonic terrain in the region (for up-welling) or only higher than its immediate moat-like surroundings (melt-through and refreezing). Several authors have taken up this challenge, presenting topographic maps to refute the melt-through model by showing high elevations for chaos. However, details on the methods (based on combinations of stereo images and photoclinometry) have been sketchy, and without quantitative analyses of precision. For example, near Tyre, topographic maps and profiles reportedly show elevated chaos areas. Yet the elevations differ between published results by much more than the purported 10m precision. Moreover, high-elevation portions of profiles that were labeled as chaos are actually tectonic terrain. Stereo actually shows that major chaos areas are lower than the tectonic terrain in the area. Also, variations in elevation within the tectonic terrain are so great that differences from chaotic terrain are in the noise. Moreover, our error-analyses for both stereo and photoclinometry indicate that uncertainties are greater than reported differences between elevations of chaotic and tectonic terrain. For example, stereo-based models may exaggerate the height of chaos by favoring rafts as tie features, and photoclinometry is sensitive to an uncertain photometric function and to sub-pixel slope variations. To paraphrase Mark Twain, reports of the death of the melt-through model have been greatly exaggerated. Any results based on topography should not be accepted until the methods involved have been subjected to rigorous and transparent quantitative evaluation.

  6. Geostatistical modeling of topography using auxiliary maps

    NASA Astrophysics Data System (ADS)

    Hengl, Tomislav; Bajat, Branislav; Blagojevi?, Dragan; Reuter, Hannes I.

    2008-12-01

    This paper recommends computational procedures for employing auxiliary maps, such as maps of drainage patterns, land cover and remote-sensing-based indices, directly in the geostatistical modeling of topography. The methodology is based on the regression-kriging technique, as implemented in the R package gstat. The computational procedures are illustrated using a case study in the south-west part of Serbia. Two point data sets were used for geostatistical modeling: (1) 2051 elevation points were used to generate DEMs and (2) an independent error assessment data set (1020 points) was used to assess errors in the topo-DEM and the SRTM-DEM. Four auxiliary maps were used to improve generation of DEMs from point data: (1) distance to streams, (2) terrain complexity measured by standard deviation filter, (3) analytical hillshading map and (4) NDVI map derived from the Landsat image. The auxiliary predictors were significantly correlated with elevations (adj.R2=0.20) and DEM errors (adj.R2=0.27). By including auxiliary maps in the geostatistical modeling of topography, realizations of DEMs can be generated that represent geomorphology of a terrain more accurately. In addition, downscaling of a coarse 3 arcsec SRTM DEM using auxiliary maps and regression-kriging is demonstrated using the same case study. A methodological advantage of regression-kriging, compared to splines, is the possibility to automate the data processing and incorporate multiple auxiliary predictors. The remaining open issues are computational efficiency, application of local regression-kriging algorithms and preparation of suitable auxiliary data layers for such analyses.

  7. Surface Water and Ocean Topography (SWOT) mission

    NASA Astrophysics Data System (ADS)

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

    2012-09-01

    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.

  8. Seismological Modeling of Inner Core Boundary Topography

    NASA Astrophysics Data System (ADS)

    de Silva, S. M.; Cormier, V. F.; Zheng, Y.; Hernlund, J. W.

    2013-12-01

    Earth's solid inner core is created by the slow freezing of a well-mixed, vigorously convecting, iron-rich outer core. The structure near inner core boundary (ICB) has a significant effect on core dynamics including the mechanisms behind the growth of inner core and the compositional convection driving the geodynamo. A dynamically unstable process of compaction of solids and expulsion of fluids at a solidifying boundary can produce small-scale corrugations of the inner core boundary with heights on the order of 1km, consistent with a number of previous observations of body waves interacting with the ICB. We determine topographic models of a rough ICB that match the observed PKiKP and PKP-Cdiff waveforms. In order to constrain parameters of the modeled topography, the observations are compared with synthetic seismograms generated using a boundary element method that exploits a dense discretization along the surface of the ICB. This method of modeling is more computationally efficient and flexible than finite difference methods previously used in these studies, which in turn allows us to make our calculations more accurate. The implementation of the modeling procedure starts by setting up boundary element method for a two-layered homogeneous interior and exterior of ICB system and later adds the real Earth's radial inhomogeneity to the exterior where propagation of rays are calculated using ray theory. An initial test is carried out to identify the parametric limits of models where ICB topography begins to impose observable effects to the PKiKP coda at approximately 50 great circle distance.

  9. Evolution of Neogene Dynamic Topography in Madagascar

    NASA Astrophysics Data System (ADS)

    Paul, J. D.; Roberts, G.; White, N. J.

    2012-12-01

    Madagascar is located on the fringes of the African superswell. Its position and the existence of a +30 mGal long wavelength free-air gravity anomaly suggest that its present-day topography is maintained by convective circulation of the sub-lithospheric mantle. Residual depth anomalies of oceanic crust encompassing the island imply that Madagascar straddles a dynamic topographic gradient. In June-July 2012, we examined geologic evidence for Neogene uplift around the Malagasy coastline. Uplifted coral reef deposits, fossil beach rock, and terraces demonstrate that the northern and southern coasts are probably being uplifted at a rate of ~0.2 mm/yr. Rates of uplift clearly vary around the coastline. Inland, extensive peneplains occur at elevations of 1 - 2 km. These peneplains are underlain by 10 - 20 m thick laterite deposits, and there is abundant evidence for rapid erosion (e.g. lavaka). Basaltic volcanism also occurred during Neogene times. These field observations can be combined with an analysis of drainage networks to determine the spatial and temporal pattern of convectively driven uplift. ~100 longitudinal river profiles were extracted from a digital elevation model of Madagascar. An inverse model is then used to minimize the misfit between observed and calculated river profiles as a function of uplift rate history. During inversion, the residual misfit decreases from ~20 to ~4. Our results suggest that youthful and rapid uplift of 1-2 km occurred at rates of 0.2-0.4 mm/yr during the last ˜15 Myr. The algorithm resolves distinct phases of uplift which generate localized swells of high topography and relief (e.g. the Hauts Plateaux). Our field observations and modeling indicate that the evolution of drainage networks may contain useful information about mantle convective processes.

  10. Effect of surface topography on stress concentration factor

    NASA Astrophysics Data System (ADS)

    Cheng, Zhengkun; Liao, Ridong

    2015-11-01

    Neuber rule and Arola-Ramulu model are widely used to predict the stress concentration factor of rough specimens. However, the height parameters and effective valley radius used in these two models depend strongly on the resolution of the roughness-measuring instruments and are easily introduce measuring errors. Besides, it is difficult to find a suitable parameter to characterize surface topography to quantitatively describe its effect on stress concentration factor. In order to overcome these disadvantages, profile moments are carried out to characterize surface topography, surface topography is simulated by superposing series of cosine components, the stress concentration factors of different micro cosine-shaped surface topographies are investigated by finite element analysis. In terms of micro cosine-shaped surface topography, an equation using the second profile moment to estimate the stress concentration factor is proposed, predictions for the stress concentration factor using the proposed expression are within 10% error compared with the results of finite element analysis, which are more accurate than other models. Moreover, the proposed equation is applied to the real surface topography machined by turning. Predictions for the stress concentration factor using the proposed expression are within 10% of the maximum stress concentration factors and about 5% of the effective stress concentration factors estimated from the finite element analysis for three levels of turning surface topographies under different simulated scales. The proposed model is feasible in predicting the stress concentration factors of real machined surface topographies.

  11. Cokriging surface elevation and seismic refraction data for bedrock topography

    SciTech Connect

    Nyquist, J.E.; Doll, W.E. ); Davis, R.K. ); Hopkins, R.A. )

    1992-01-01

    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.

  12. Cokriging surface elevation and seismic refraction data for bedrock topography

    SciTech Connect

    Nyquist, J.E.; Doll, W.E.; Davis, R.K.; Hopkins, R.A.

    1992-11-01

    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.

  13. Quantifying landscape evolution response to changes in dynamic topography (Invited)

    NASA Astrophysics Data System (ADS)

    Moucha, R.; Ruetenik, G. A.; Braun, J.; Guillocheau, F.; Hoke, G. D.

    2013-12-01

    Earth's topography is a convolution of complex interactions of the mantle, the crust and surface processes, where the latter are controlled by the dynamics of the atmosphere and sea level change. An outstanding problem in landscape evolution and continental dynamics is the delineation of mantle convective flow induced topography (termed dynamic topography) from the geological record. Therefore, to unravel this record, we need to first understand the complex landscape evolution response to long-term dynamic forcing from the mantle in a controlled study. Recent advances in landscape evolution modeling have overcome a previous limitation in spatial and temporal scales making modeling the effects of large-scale long-term features such as dynamic topography, possible. In this study, we utilize FastScape (Braun and Willett, 2013) to quantify the effect of changes in dynamic topography of Africa on landscape evolution and sediment supply to its margins. We utilize a novel iterative approach that uses backward in time advected models of dynamic topography as the initial drivers of uplift/subsidence in the landscape evolution model. Subsequently, with the margins' sedimentary record acting as constraints we refine the changes in topography as a function of time. Our goal is to obtain a geodynamically and geologically consistent model of African topography throughout the late Cenozoic.

  14. Investigation of the mode of compensation of Venus topography

    NASA Technical Reports Server (NTRS)

    Morgan, Paul

    1986-01-01

    The Venus gravity data derived from the Pioneer Venus Orbiter indicates a strong correlation of gravity to topography at all resolvable wavelengths. Focus was on an analysis in the spatial domain, using a geophysical model of topographic compensation together with the topography data to compute gravity vectors corresponding to the observed data and comparison of the calculated and observed gravity vectors.

  15. Video Animation of Ocean Topography From TOPEX/POSEIDON

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng; Leconte, Denis; Pihos, Greg; Davidson, Roger; Kruizinga, Gerhard; Tapley, Byron

    1993-01-01

    Three video loops showing various aspects of the dynamic ocean topography obtained from the TOPEX/POSEIDON radar altimetry data will be presented. The first shows the temporal change of the global ocean topography during the first year of the mission. The time-averaged mean is removed to reveal the temporal variabilities. Temporal interpolation is performed to create daily maps for the animation. A spatial smoothing is also performed to retain only the large-sale features. Gyre-scale seasonal changes are the main features. The second shows the temporal evolution of the Gulf Stream. The high resolution gravimetric geoid of Rapp is used to obtain the absolute ocean topography. Simulated drifters are used to visualize the flow pattern of the current. Meanders and rings of the current are the main features. The third is an animation of the global ocean topography on a spherical earth. The JGM-2 geoid is used to obtain the ocean topography...

  16. Stereo Pair: Inverted Topography, Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The Meseta de Somuncura is a broad plateau capped by basalt. Near its western edge is evidence of multiple volcanic events and a complex erosion history. Most notable are the long, narrow-, and winding lava flows that run across most of the right side of the image. These formed from low-viscosity lava that flowed down gullies over fairly flat terrain. Later, erosion of the landscape continued and the solidified flows were more resistant than the older surrounding rocks. Consequently, the flows became the ridges we see here. This natural process of converting gullies to ridges is called topographic inversion. See image PIA02755 (upper left corner) for a good example of topographic inversion in its earlier stages.

    Other features seen here include numerous and varied closed depressions. The regional drainage is not well integrated, and drainage ends up in salty lakes (blue if shallow, black if deep). Wind streaks indicate that winds blow toward the east (right) and blow salt grains off the lakebeds when dry. The bowtie pattern in the upper left has resulted from differing grazing practices among fenced fields.

    This cross-eyed stereoscopic image pair was generated using topographic data from the Shuttle Radar Topography Mission, combined with an enhanced Landsat 7satellite color image. The topography data are used to create two differing perspectives of a single image, one perspective for each eye. In doing so, each point in the image is shifted slightly, depending on its elevation. When stereoscopically merged, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7 Thematic Mapper image used here was provided to the SRTM project by the United States Geological Survey, Earth Resources Observation Systems (EROS) Data Center,Sioux Falls, South Dakota.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.

    Size: 21.5 kilometers (13.4 miles) x 27.2 kilometers (16.9 miles) Location: 41.6 deg. South lat., 67.9 deg. West lon. Orientation: North toward upper left Image Data: Landsat bands 1,4,7 in blue, green, red Date Acquired: February 19, 2000 (SRTM), January 22, 2000 (Landsat)

  17. New Global Bathymetry and Topography Model Grids

    NASA Astrophysics Data System (ADS)

    Smith, W. H.; Sandwell, D. T.; Marks, K. M.

    2008-12-01

    A new version of the "Smith and Sandwell" global marine topography model is available in two formats. A one-arc-minute Mercator projected grid covering latitudes to +/- 80.738 degrees is available in the "img" file format. Also available is a 30-arc-second version in latitude and longitude coordinates from pole to pole, supplied as tiles covering the same areas as the SRTM30 land topography data set. The new effort follows the Smith and Sandwell recipe, using publicly available and quality controlled single- and multi-beam echo soundings where possible and filling the gaps in the oceans with estimates derived from marine gravity anomalies observed by satellite altimetry. The altimeter data have been reprocessed to reduce the noise level and improve the spatial resolution [see Sandwell and Smith, this meeting]. The echo soundings database has grown enormously with new infusions of data from the U.S. Naval Oceanographic Office (NAVO), the National Geospatial-intelligence Agency (NGA), hydrographic offices around the world volunteering through the International Hydrographic Organization (IHO), and many other agencies and academic sources worldwide. These new data contributions have filled many holes: 50% of ocean grid points are within 8 km of a sounding point, 75% are within 24 km, and 90% are within 57 km. However, in the remote ocean basins some gaps still remain: 5% of the ocean grid points are more than 85 km from the nearest sounding control, and 1% are more than 173 km away. Both versions of the grid include a companion grid of source file numbers, so that control points may be mapped and traced to sources. We have compared the new model to multi-beam data not used in the compilation and find that 50% of differences are less than 25 m, 95% of differences are less than 130 m, but a few large differences remain in areas of poor sounding control and large-amplitude gravity anomalies. Land values in the solution are taken from SRTM30v2, GTOPO30 and ICESAT data. GEBCO has agreed to adopt this model and begin updating it in 2009. Ongoing tasks include building an uncertainty model and including information from the latest IBCAO map of the Arctic Ocean.

  18. Topography and Volcanoes on Io (color)

    NASA Technical Reports Server (NTRS)

    1997-01-01

    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

  19. The length-scaling properties of topography

    NASA Technical Reports Server (NTRS)

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

    1994-01-01

    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.

  20. Imaging, Reconstruction, And Display Of Corneal Topography

    NASA Astrophysics Data System (ADS)

    Klyce, Stephen D.; Wilson, Steven E.

    1989-12-01

    The cornea is the major refractive element in the eye; even minor surface distortions can produce a significant reduction in visual acuity. Standard clinical methods used to evaluate corneal shape include keratometry, which assumes the cornea is ellipsoidal in shape, and photokeratoscopy, which images a series of concentric light rings on the corneal surface. These methods fail to document many of the corneal distortions that can degrade visual acuity. Algorithms have been developed to reconstruct the three dimensional shape of the cornea from keratoscope images, and to present these data in the clinically useful display of color-coded contour maps of corneal surface power. This approach has been implemented on a new generation video keratoscope system (Computed Anatomy, Inc.) with rapid automatic digitization of the image rings by a rule-based approach. The system has found clinical use in the early diagnosis of corneal shape anomalies such as keratoconus and contact lens-induced corneal warpage, in the evaluation of cataract and corneal transplant procedures, and in the assessment of corneal refractive surgical procedures. Currently, ray tracing techniques are being used to correlate corneal surface topography with potential visual acuity in an effort to more fully understand the tolerances of corneal shape consistent with good vision and to help determine the site of dysfunction in the visually impaired.

  1. Mercury's Global Topography from Radar Ranging Data

    NASA Technical Reports Server (NTRS)

    Anderson, J. D.; Schubert, G.; Asmar, S. W.; Jurgens, R. F.; Lau, E. L.; Moore, W. B.; Slade, M. A., III; Standish, E. M., Jr.

    2001-01-01

    When Mercury's radius is expanded in Legendre functions to the second degree and order, the systematic error in radar ranging data is reduced substantially. Previously, data spanning an observing interval from 1966 to 1990 were used to infer an equatorial ellipticity (a - b)/a = (540 +/- 54) X 10(exp -6) and a center-of-figure minus center-of-mass offset of (640 +/- 78) m. The magnitude of this equatorial center of figure offset implies an excess crustal thickness of 12 km or less, comparable to the Moon's excess. By comparing the equatorial ellipticity with the Mariner 10 gravity field, and assuming Airy isostatic compensation, bounds on crustal thickness can be derived. Mercury's crustal thickness is in the range from 100 to 300 km. The Mercury radar ranging observing interval has been extended from 1966 to the present. In addition, improvements in data reduction techniques have resulted in a set of Mercury ranging data less affected by systematic error, in particular the biases introduced by local topographic variations. We use this new set of reduced ranging data to improve Mercury's global topography and center-of-figure minus center-of-mass offset. New results on crustal thickness are derived, and prospects for further improvement with Mercury Orbiter data are discussed.

  2. Epitope topography controls bioactivity in supramolecular nanofibers

    PubMed Central

    Sur, Shantanu; Tantakitti, Faifan; Matson, John B.; Stupp, Samuel I.

    2015-01-01

    Incorporating bioactivity into artificial scaffolds using peptide epitopes present in the extracellular matrix (ECM) is a well-known approach. A common strategy has involved epitopes that provide cells with attachment points and external cues through interaction with integrin receptors. Although a variety of bioactive sequences have been identified so far, less is known about their optimal display in a scaffold. We report here on the use of self-assembled peptide amphiphile (PA) nanofiber matrices to investigate the impact of spatial presentation of the fibronectin derived epitope RGDS on cell response. Using one, three, or five glycine residues, RGDS epitopes were systematically spaced out from the surface of the rigid nanofibers. We found that cell morphology was strongly affected by the separation of the epitope from the nanofiber surface, with the longest distance yielding the most cell-spreading, bundling of actin filaments, and a round-to-polygonal transformation of cell shape. Cell response to this type of epitope display was also accompanied with activated integrin-mediated signaling and formation of stronger adhesions between cells and substrate. Interestingly, unlike length, changing the molecular flexibility of the linker had minimal influence on cell behavior on the substrate for reasons that remain poorly understood. The use in this study of high persistence length nanofibers rather than common flexible polymers allows us to conclude that epitope topography at the nanoscale structure of a scaffold influences its bioactive properties independent of epitope density and mechanical properties. PMID:25745558

  3. Venus atmosphere and extreme surface topography

    NASA Astrophysics Data System (ADS)

    Zasova, L.; Khatuntsev, I.; Patsaeva, M.; Ignatiev, N.; Rodin, A.; Turin, A.; Markiewicz, W.; Piccioni, G.

    2015-10-01

    The temperature fields at several levels in the Venus mesosphere(60-95 km)as well as the altitude of the upper boundary of clouds retrieved from Venera-15 (FS-V15) [1], and the zonal wind fields and albedo of the upper clouds, measured by VMC Venus Express [2], and altitude of the upper boundary of clouds VIRTIS-M VEX [3] data are compared with the topographic map, obtained by Magellan [4] . The results show that the isotherms and the altitude isolines of the upper clouds boundary reproduce the extended surface features Ishtar and Atalanta Planitia. In turn, the shapes of wind isovelocities and albedo at the upper boundary of clouds (VMC) closely follow the details of relief of Terra Aphrodite as well the isolines of altitude of the cloud tops (VIRTIS). In all cases the isolines are shifted with respect to topography by about 30° in the direction of superrotation. Non-hydrostatic general circulation model of the Venus atmosphere[5] demonstrates that the major topographic features such as Maxwell Montes and Terra Aphrodite provide a prominent impact on the atmospheric dynamics at levels as high as 90-95 km.

  4. Inversion of topography in Martian highland terrains

    SciTech Connect

    De Hon, R.A.

    1985-01-01

    Ring furrows are flat-floored trenches, circulate in plan view, forming rings 7 to 50 km in diameter. Typically, ring furrows, which are 0.5 km deep and 2 to 10 km wide, surround a central, flat-topped, circular mesa or plateau. The central plateau is about the same elevation or lower than the plain outside the ring. Ring furrows are unique features of the dissected martian uplands. Related landforms range from ring furrows with fractured central plateaus to circular mesas without encircling moats. Ring furrows are superposed on many types of materials, but they are most common cratered plateau-type materials that are interpreted as volcanic flow material overlying ancient cratered terrain. The ring shape and size suggest that they are related to craters partially buried by lava flows. Ring furrows were formed by preferential removal of exposed rims of partially buried craters. Evidence of overland flow of water is lacking except within the channels. Ground ice decay and sapping followed by fluvial erosion are responsible for removal of the less resistant rim materials. Thus, differential erosion has caused a reversal of topography in which the originally elevated rim is reduced to negative relief.

  5. Wettability control by DLC coated nanowire topography

    NASA Astrophysics Data System (ADS)

    Li, Zihui; Meng, Fanhao; Liu, Xuanyong

    2011-04-01

    Here we have developed a convenient method to fabricate wettability controllable surfaces that can be applied to various nanostructured surfaces with complex shapes for different industrial needs. Diamond-like carbon (DLC) films were synthesized on titanium substrate with a nanowire structured surface using plasma immersion ion implantation and deposition (PIII&D). The nanostructure of the DLC films was characterized by field emission scanning electron microscopy and found to grow in a rippling layer-by-layer manner. Raman spectroscopy was used to investigate the different bonding presented in the DLC films. To determine the wettability of the samples, water contact angles were measured and found to vary in the range of 50-141. The results indicated that it was critical to construct a proper surface topography for high hydrophobicity, while suitable ID/IG and sp2/sp3 ratios of the DLC films had a minor contribution. Superhydrophobicity could be achieved by further CF4 implantation on suitably structured DLC films and was attributed to the existence of fluorine. In order to maintain the nanostructure during CF4 implantation, it was favorable to pre-deposit an appropriate carbon content on the nanostructure, as a nanostructure with low carbon content would be deformed during CF4 implantation due to local accumulation of surface charge and the following discharge resulting from the low conductivity.

  6. Wettability control by DLC coated nanowire topography.

    PubMed

    Li, Zihui; Meng, Fanhao; Liu, Xuanyong

    2011-04-01

    Here we have developed a convenient method to fabricate wettability controllable surfaces that can be applied to various nanostructured surfaces with complex shapes for different industrial needs. Diamond-like carbon (DLC) films were synthesized on titanium substrate with a nanowire structured surface using plasma immersion ion implantation and deposition (PIII&D). The nanostructure of the DLC films was characterized by field emission scanning electron microscopy and found to grow in a rippling layer-by-layer manner. Raman spectroscopy was used to investigate the different bonding presented in the DLC films. To determine the wettability of the samples, water contact angles were measured and found to vary in the range of 50-141. The results indicated that it was critical to construct a proper surface topography for high hydrophobicity, while suitable I(D)/I(G) and sp/sp ratios of the DLC films had a minor contribution. Superhydrophobicity could be achieved by further CF? implantation on suitably structured DLC films and was attributed to the existence of fluorine. In order to maintain the nanostructure during CF? implantation, it was favorable to pre-deposit an appropriate carbon content on the nanostructure, as a nanostructure with low carbon content would be deformed during CF? implantation due to local accumulation of surface charge and the following discharge resulting from the low conductivity. PMID:21343636

  7. Dynamic and reversible surface topography influences cell morphology

    PubMed Central

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

    2015-01-01

    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

  8. Characterizing smoking topography of cannabis in heavy users

    PubMed Central

    Stitzer, Maxine L.; Vandrey, Ryan

    2013-01-01

    Rationale Little is known about the smoking topography characteristics of heavy cannabis users. Such measures may be able to predict cannabis use-related outcomes and could be used to validate self-reported measures of cannabis use. Objectives The current study was conducted to measure cannabis smoking topography characteristics during periods of ad libitum use and to correlate topography assessments with measures of self-reported cannabis use, withdrawal and craving during abstinence, and cognitive task performance. Methods Participants (N=20) completed an inpatient study in which they alternated between periods of ad libitum cannabis use and abstinence. Measures of self-reported cannabis use, smoking topography, craving, withdrawal, and sleep measures were collected. Results Participants smoked with greater intensity (e.g., greater volume, longer duration) on initial cigarette puffs with a steady decline on subsequent puffs. Smoking characteristics were significantly correlated with severity of withdrawal, notably sleep quality and architecture, and craving during abstinence, suggesting dose-related effects of cannabis use on these outcomes. Smoking characteristics generally were not significantly associated with cognitive performance. Smoking topography measures were significantly correlated with self-reported measures of cannabis use, indicating validity of these assessments, but topography measures were more sensitive than self-report in predicting cannabis-related outcomes. Conclusions A dose–effect relationship between cannabis consumption and outcomes believed to be clinically important was observed. With additional research, smoking topography assessments may become a useful clinical tool. PMID:21922170

  9. SRTM Anaglyph: Inverted Topography, Patagonia, Argentina

    NASA Technical Reports Server (NTRS)

    2000-01-01

    The Meseta de Somuncura is a broad plateau capped by basalt. Near its western edge is evidence of multiple volcanic events and a complex erosion history. Most notable are the long, narrow, and winding lava flows that run across most of the right side of the image. These formed from low-viscosity lava that flowed down gullies over fairly flat terrain. Later, erosion of the landscape continued, and the solidified flows were more resistant than the older surrounding rocks. Consequently, the flows became the ridges we see here. This natural process of converting gullies to ridges is called topographic inversion. See image PIA02755 (upper left corner) for a good example of topographic inversion in its earlier stages.

    Other features seen here include numerous and varied closed depressions. The regional drainage is not well integrated, but instead the drainage ends up in salty lakes (dark water, some with bright shores). Wind streaks indicate that winds blow toward the east (right) and blow salt grains off the lake beds when dry. The bowtie pattern in the upper left has resulted from differing grazing practices among fenced fields.

    This anaglyph was generated by first draping a Landsat Thematic Mapper image over a topographic map from the Shuttle Radar Topography Mission, then producing the two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of the Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and the right eye with a blue filter.

    Landsat satellites have provided visible light and infrared images of the Earth continuously since 1972. SRTM topographic data match the 30-meter (99-foot) spatial resolution of most Landsat images and provide a valuable complement for studying the historic and growing Landsat data archive. The Landsat 7 Thematic Mapper image used here was provided to the SRTM project by the United States Geological Survey, Earth Resources Observation Systems (EROS) Data Center,Sioux Falls, South Dakota.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.

    Size: 21.5 kilometers (13.4 miles) x 27.2 kilometers (16.9 miles) Location: 41.6 deg. South lat., 67.9 deg. West lon. Orientation: North toward upper left Image Data: Landsat band 7 (short infrared) Date Acquired: February 19, 2000 (SRTM), January 22, 2000 (Landsat)

  10. Global dynamic topography: geoscience communities requirements

    NASA Astrophysics Data System (ADS)

    Dewez, T.; Costeraste, J.

    2012-04-01

    The advent of free-of-charge global topographic data sets SRTM and Aster GDEM have enabled testing a host of geoscience hypotheses. This is because they first revealed the relief of previously unavailable earth landscapes, enabled quantitative geomorphometric analyses across entire landscapes and improved the resolution of measurements. Availability of such data is now considered standard, and though resolved at 30-m to 90-m pixel, which is amazing seeing where we come from, they are now regarded as mostly obsolete given the sub-meter imagery coming through web services like Google Earth. Geoscientists now appear to desire two additional features: field-scale-compatible elevation datasets (i.e. meter-scale digital models and sub-meter elevation precision) and dispose of regularly updated topography to retrieve earth surface changes, while retaining the key for success: data availability at no charge. A new satellite instrument is currently under phase 0 study at CNES, the French space agency, to fulfil these aims. The scientific community backing this demand is that of natural hazards, glaciology and to a lesser extent the biomass community. The system under study combines a native stereo imager and a lidar profiler. This combination provides spatially resolved elevation swaths together with absolute along-track elevation control point profiles. Data generated through this system, designed for revisit time better than a year, is intended to produce not only single acquisition digital surface models, colour orthoimages and small footprint full-wave-form lidar profiles to update existing topographic coverages, but also time series of them. This enables 3D change detection with centimetre-scale planimetric precision and metric vertical precision, in complement of classical spectral change appoaches. The purpose of this contribution, on behalf of the science team, is to present the mission concepts and philosophy and the scientific needs for such instrument including foreseen societal benefits.

  11. Epithelial topography for repetitive tooth formation

    PubMed Central

    Gaete, Marcia; Fons, Juan Manuel; Popa, Elena Mădălina; Chatzeli, Lemonia; Tucker, Abigail S.

    2015-01-01

    ABSTRACT During the formation of repetitive ectodermally derived organs such as mammary glands, lateral line and teeth, the tissue primordium iteratively initiates new structures. In the case of successional molar development, new teeth appear sequentially in the posterior region of the jaw from Sox2+ cells in association with the posterior aspect of a pre-existing tooth. The sequence of molar development is well known, however, the epithelial topography involved in the formation of a new tooth is unclear. Here, we have examined the morphology of the molar dental epithelium and its development at different stages in the mouse in vivo and in molar explants. Using regional lineage tracing we show that within the posterior tail of the first molar the primordium for the second and third molar are organized in a row, with the tail remaining in connection with the surface, where a furrow is observed. The morphology and Sox2 expression of the tail retains characteristics reminiscent of the earlier stages of tooth development, such that position along the A-P axes of the tail correlates with different temporal stages. Sox9, a stem/progenitor cell marker in other organs, is expressed mainly in the suprabasal epithelium complementary with Sox2 expression. This Sox2 and Sox9 expressing molar tail contains actively proliferating cells with mitosis following an apico-basal direction. Snail2, a transcription factor implicated in cell migration, is expressed at high levels in the tip of the molar tail while E-cadherin and laminin are decreased. In conclusion, our studies propose a model in which the epithelium of the molar tail can grow by posterior movement of epithelial cells followed by infolding and stratification involving a population of Sox2+/Sox9+ cells. PMID:26538639

  12. Science in Motion: Isolated Araneiform Topography

    NASA Technical Reports Server (NTRS)

    2007-01-01

    [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.

  13. Functional topography of the dorsomedial hypothalamus.

    PubMed

    Tanaka, Mutsumi; McAllen, Robin M

    2008-02-01

    The dorsomedial hypothalamus (DMH) has been proposed to play key roles in both the defense reaction to acute stress and in the thermoregulatory response to cold. We reasoned that the autonomic/respiratory motor patterns of these responses would be mediated by at least partly distinct DMH neuron populations. To test this, we made simultaneous recordings of phrenic nerve and plantar cutaneous vasoconstrictor (CVC) activity in 14 vagotomized, ventilated, urethane-anesthetized rats. Microinjections of d,l-homocysteic acid (DLH; 15 nl, 50 mM) were used to cause localized, short-lasting (<1 min) activation of DMH neuron clusters. Cooling the rat's trunk skin by perfusing cold water through a water jacket-activated plantar CVC activity but depressed phrenic burst rate (cold-response pattern). The expected "stress/defense response" pattern would be phrenic activation, with increased blood pressure, heart rate, and possibly CVC activity. DLH microinjections into 76 sites within the DMH region never reduced phrenic activity. They frequently increased phrenic rate and/or plantar CVC activity, but the magnitudes of those two responses were not significantly correlated. Plantar CVC responses were evoked most strongly from the dorsal hypothalamic area and most dorsal part of the dorsomedial nucleus, whereas peak phrenic rate responses were evoked from more caudal sites; their relative magnitudes varied systematically with rostrocaudal position. Tachycardia correlated with plantar CVC responses but not phrenic rate. These findings indicate that localized activation of DMH neurons does not evoke full "cold-response" or stress/defense response patterns, but they demonstrate the existence of significant functional topography within the DMH region. PMID:18077509

  14. Tectonic control on the persistence of glacially sculpted topography

    PubMed Central

    Prasicek, Günther; Larsen, Isaac J.; Montgomery, David R.

    2015-01-01

    One of the most fundamental insights for understanding how landscapes evolve is based on determining the extent to which topography was shaped by glaciers or by rivers. More than 104 years after the last major glaciation the topography of mountain ranges worldwide remains dominated by characteristic glacial landforms such as U-shaped valleys, but an understanding of the persistence of such landforms is lacking. Here we use digital topographic data to analyse valley shapes at sites worldwide to demonstrate that the persistence of U-shaped valleys is controlled by the erosional response to tectonic forcing. Our findings indicate that glacial topography in Earth's most rapidly uplifting mountain ranges is rapidly replaced by fluvial topography and hence valley forms do not reflect the cumulative action of multiple glacial periods, implying that the classic physiographic signature of glaciated landscapes is best expressed in, and indeed limited by, the extent of relatively low-uplift terrain. PMID:26271245

  15. Tectonic control on the persistence of glacially sculpted topography

    NASA Astrophysics Data System (ADS)

    Prasicek, Gnther; Larsen, Isaac J.; Montgomery, David R.

    2015-08-01

    One of the most fundamental insights for understanding how landscapes evolve is based on determining the extent to which topography was shaped by glaciers or by rivers. More than 104 years after the last major glaciation the topography of mountain ranges worldwide remains dominated by characteristic glacial landforms such as U-shaped valleys, but an understanding of the persistence of such landforms is lacking. Here we use digital topographic data to analyse valley shapes at sites worldwide to demonstrate that the persistence of U-shaped valleys is controlled by the erosional response to tectonic forcing. Our findings indicate that glacial topography in Earth's most rapidly uplifting mountain ranges is rapidly replaced by fluvial topography and hence valley forms do not reflect the cumulative action of multiple glacial periods, implying that the classic physiographic signature of glaciated landscapes is best expressed in, and indeed limited by, the extent of relatively low-uplift terrain.

  16. Surface topography and the impact on fatigue performance

    NASA Astrophysics Data System (ADS)

    Ardi, D. T.; Li, Y. G.; Chan, K. H. K.; Blunt, L.; Bache, M. R.

    2015-03-01

    Areal characterization was applied to plain fatigue specimens manufactured from a nickel-based superalloy, Alloy 720Li, to determine the impact of machined/finished surface topography on fatigue performance of this material. Samples were subjected to fatigue testing in the as-turned and shot peened conditions to study the interaction between residual stresses and topography in influencing the fatigue performance. The turning process was deliberately manipulated to produce three distinct finishes which were subsequently given an identical shot peening, resulting in six grades of surface topography. Surface topography was found to influence fatigue even in the presence of peened compressive residual stresses by promoting crack initiation at valley sites. Both the roughness amplitude and spatial characteristics of the surface were found to be important when correlating to fatigue performance.

  17. X-ray topography of a lysozyme crystal

    SciTech Connect

    Stojanoff,V.; Siddons, D.

    1996-01-01

    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.

  18. Geoid height versus topography for oceanic plateaus and swells

    NASA Technical Reports Server (NTRS)

    Sandwell, David T.; Mackenzie, Kevin R.

    1989-01-01

    Gridded geoid height data (Marsh et al.l, 1986) and gridded bathymetry data (Van Wykhouse, 1973) are used to estimate the average compensation depths of 53 oceanic swells and plateaus. The relationship between geoid height and topography is examined using Airy and thermal compensation models. It is shown that geoid height is linearly related to topography between wavelengths of 400 and 4000 m as predicted by isostatic compensation models. The geoid/topography ratio is dependent on the average depth of compensation. The intermediate geoid/topography ratios of most thermal swells are interpreted as a linear combination of the decaying thermal swell signature and that of the persisting Airy-compensated volcanic edifice.

  19. Stimulus control topography coherence theory: Foundations and extensions

    PubMed Central

    McIlvane, William J.; Dube, William V.

    2003-01-01

    Stimulus control topography refers to qualitative differences among members of a functional stimulus class. Stimulus control topography coherence refers to the degree of concordance between the stimulus properties specified as relevant by the individual arranging a reinforcement contingency (behavior analyst, experimenter, teacher, etc.) and the stimulus properties that come to control the behavior of the organism (experimental subject, student, etc.) that experiences those contingencies. This paper summarizes the rationale for analyses of discrimination learning outcomes in terms of stimulus control topography coherence and briefly reviews some of the foundational studies that led to this perspective. We also suggest directions for future research, including pursuit of conceptual and methodological challenges to a complete stimulus control topography coherence analysis of processes involved in discriminated and generalized operants. ImagesFigure 3Figure 5 PMID:22478402

  20. Calculation of irrotational wind pattern with application to Cleveland topography

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1972-01-01

    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.

  1. Influence of local topography on precision irrigation management

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Precision irrigation management is currently accomplished using spatial information about soil properties through soil series maps or electrical conductivity (EC measurements. Crop yield, however, is consistently influenced by local topography, both in rain-fed and irrigated environments. Utilizing ...

  2. Engineering microscale topographies to control the cellsubstrate interface

    PubMed Central

    Nikkhah, Mehdi; Edalat, Faramarz; Manoucheri, Sam; Khademhosseini, Ali

    2013-01-01

    Cells in their in vivo microenvironment constantly encounter and respond to a multitude of signals. While the role of biochemical signals has long been appreciated, the importance of biophysical signals has only recently been investigated. Biophysical cues are presented in different forms including topography and mechanical stiffness imparted by the extracellular matrix and adjoining cells. Microfabrication technologies have allowed for the generation of biomaterials with microscale topographies to study the effect of biophysical cues on cellular function at the cellsubstrate interface. Topographies of different geometries and with varying microscale dimensions have been used to better understand cell adhesion, migration, and differentiation at the cellular and sub-cellular scales. Furthermore, quantification of cell-generated forces has been illustrated with micropillar topographies to shed light on the process of mechanotransduction. In this review, we highlight recent advances made in these areas and how they have been utilized for neural, cardiac, and musculoskeletal tissue engineering application. PMID:22521491

  3. 2. GENERAL VIEW SHOWING RELATION OF BRIDGE TO THE TOPOGRAPHY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. GENERAL VIEW SHOWING RELATION OF BRIDGE TO THE TOPOGRAPHY OF THE APPROACH ROAD. - Speicher Bridge, Church Road over Tulpehocken Creek between Penn & North Heidelberg Townships, Bernville, Berks County, PA

  4. 23. SPILLWAY NO. 1 LOWER END TOPOGRAPHY AND SECTIONS. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. SPILLWAY NO. 1 - LOWER END TOPOGRAPHY AND SECTIONS. February 1934. Reference BS-150. - Cushman No. 1 Hydroelectric Power Plant, Spillway, North Fork of Skokomish River, 5 miles West of Hood Canal, Hoodsport, Mason County, WA

  5. Tectonic control on the persistence of glacially sculpted topography.

    PubMed

    Prasicek, Günther; Larsen, Isaac J; Montgomery, David R

    2015-01-01

    One of the most fundamental insights for understanding how landscapes evolve is based on determining the extent to which topography was shaped by glaciers or by rivers. More than 10(4) years after the last major glaciation the topography of mountain ranges worldwide remains dominated by characteristic glacial landforms such as U-shaped valleys, but an understanding of the persistence of such landforms is lacking. Here we use digital topographic data to analyse valley shapes at sites worldwide to demonstrate that the persistence of U-shaped valleys is controlled by the erosional response to tectonic forcing. Our findings indicate that glacial topography in Earth's most rapidly uplifting mountain ranges is rapidly replaced by fluvial topography and hence valley forms do not reflect the cumulative action of multiple glacial periods, implying that the classic physiographic signature of glaciated landscapes is best expressed in, and indeed limited by, the extent of relatively low-uplift terrain. PMID:26271245

  6. The Effect of Surface Topography on Interface Stresses During Peeling

    NASA Astrophysics Data System (ADS)

    Xu, Ye; Dufresne, Eric

    2012-02-01

    Surface topography can have a large impact on the adhesive strength of soft interfaces. While previous experiments have revealed some of the underlying mechanisms, there has been no direct measurement of interface stresses during adhesive failure. We use traction force microscopy to measure the microscopic distribution of interface stresses during peeling. We focus on the relationship between local stresses and topography near the peeling front.

  7. Lower mantle heterogeneity, dynamic topography and the geoid

    NASA Technical Reports Server (NTRS)

    Hager, B. H.; Clayton, R. W.; Richards, M. A.; Comer, R. P.; Dziewonski, A. M.

    1984-01-01

    Density contrasts in the lower mantle, recently imaged using seismic tomography, drive convective flow which results in kilometers of dynamically maintained topography at the core-mantle boundary and at the Earth's surface. The total gravity field due to interior density contrasts and boundary topography predicts the largest wavelength components of the geoid remarkably well. Neglecting dynamic surface deformation leads to geoid anomalies of opposite sign than are observed.

  8. Three-dimensional inversion of CSAMT data including topography

    NASA Astrophysics Data System (ADS)

    Lin, C.; Tan, H.; Tong, T.; Zeng, W.

    2013-12-01

    CSAMT is widely used in geothermal prospecting, mineral and petroleum exploration, environmental geophysics and geological engineering. However, few data are collected on the flat surface in the field CSAMT work. Most of CSAMT data are collected in the presence of strong topography either at the source position or in the survey area. Large interpretation errors may occur in CSAMT surveys if field distortions caused by the surface topography are not considered. Therefore, the CSAMT inversion should consider the topographic effect. In this work we develop a 3D inversion algorithm for inverting CSAMT data with topography using conjugate gradient inversion method. In the 3D forward problem, the total electric and magnetic fields is separated into their primary and secondary components to calculate the response from the 3D model with irregular topography. 3D rectangular grid with stair-stepped ground-air interface is used to approximate topography. The primary electric and magnetic field can be calculated by one-dimensional modeling, using the altitude of the highest point of the topography as the altitude of the flat surface. The secondary electric and magnetic field can be calculated using the staggered-grid finite difference method. Then, the apparent resistivity and phase response can be obtained by Cagniard equation. In the 3D inversion problem, conjugate gradient method is used to invert the CSAMT apparent resistivity and phase data including topography. The background resistivity is a constant value and the anomalous resistivity is used as the inversion parameter. Only the anomalous resistivity under the surface topography is updated in the inversion. Results from the synthetic tests show the validity and stability of the inversion algorithm.

  9. Shuttle Topography Data Inform Solar Power Analysis

    NASA Technical Reports Server (NTRS)

    2013-01-01

    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."

  10. Overland Tsunami Flow through Complex Topography

    NASA Astrophysics Data System (ADS)

    Lynett, P. J.; Cox, D. T.; Park, H.; Wiebe, D. M.

    2012-12-01

    As seen in numerous Japanese eyewitness videos that captured the tsunami inundation on March 11th 2011, flow interaction with the built environment is extremely complex. In addition to the entrainment of sediment and large discrete objects such as cars and ships, tsunami energy amplification due to topographic focusing was widely observed. In coastal towns and cities, this topographic focusing was due to large structures which channelled the flow to either side, often through roadways or other low-obstruction pathways. Structures in the "line-of-fire" of this channelized flow were often found to have been inflicted with relatively greater levels of damage, while the opposite was true for structures in the flow-shadow of large buildings. In this presentation, we attempt to quantify the hydrodynamic variability of flow through complex topography, such as a city layout. Understanding this variability is of particular relevance to on-going engineering efforts to develop standards for tsunami design of coastal structures. A novel set of large-scale experimental data will be introduced and used to validate a depth-integrated model. The experiment was performed in the Tsunami Wave Basin at Oregon State University. Transient long wave flooding in a 1/50 scale model of the town of Seaside, Oregon was tested. Data from the experiment, including water elevations and co-located flow speeds, are used to confirm the simulated dynamics in the numerical model. The model is shown to be capable of accurately reproducing the instantaneous wave elevation, velocity, and momentum flux of a long wave flooding a town. It is found that the numerical prediction is sensitive to the value of the bottom roughness coefficient. The model is then extended to look at the hydrodynamics in more detail and for other cases. Predicted momentum flux values from with structures resolved, with-out structures resolved, and with spatially variable bottom roughness will be discussed. It is found that localized maximum momentum flux values can be two orders of magnitude greater than the alongshore-transect mean. A method to calculate statistical variability of hydrodynamic flow properties, such as might be used in a risk-based analysis, will be discussed.

  11. Evolution of Topography in Glaciated Mountain Ranges

    NASA Technical Reports Server (NTRS)

    Brocklehurst, Simon H.

    2002-01-01

    This thesis examines the response of alpine landscapes to the onset of glaciation. The basic approach is to compare fluvial and glacial laudscapes, since it is the change from the former to the latter that accompanies climatic cooling. This allows a detailed evaluation of hypotheses relating climate change to tectonic processes in glaciated mountain belts. Fieldwork was carried out in the eastern Sierra Nevada, California, and the Sangre de Cristo Range, Colorado, alongside digital elevation model analyses in the western US, the Southern Alps of New Zealand, and the Himalaya of northwestern Pakistan. hypothesis is overstated in its appeal to glacial erosion as a major source of relief production and subsequent peak uplift. Glaciers in the eastern Sierra Nevada and the western Sangre de Cristos have redistributed relief, but have produced only modest relief by enlarging drainage basins at the expense of low-relief topography. Glaciers have lowered valley floors and ridgelines by similar amounts, limiting the amount of "missing mass' that can be generated, and causing a decrease in drainage basin relief. The principal response of glaciated landscapes to rapid rock uplift is the development of towering cirque headwalls. This represents considerable relief production, but is not caused by glacial erosion alone. Large valley glaciers can maintain their low gradient regardless of uplift rate, which supports the "glacial buzzsaw" hypothesis. However, the inability of glaciers to erode steep hillslopes as rapidly can cause mean elevations to rise. Cosmogenic isotope dating is used to show that (i) where plucking is active, the last major glaciation removed sufficient material to reset the cosmogenic clock; and (ii) former glacial valley floors now stranded near the crest of the Sierra Nevada are at varying stages of abandonment, suggesting a cycle of drainage reorganiszation and relief inversion due to glacial erosion similar to that observed in river networks. Glaciated landscapes are quite distinct from their fluvial counterparts in both landforms and processes. Given the scarcity of purely fluvial, active mountain ranges, it is essential that glacial erosion be considered amongst the processes sculpting active orogenic belts.

  12. Spectral analysis of the gravity and topography of Mars

    NASA Technical Reports Server (NTRS)

    Bills, Bruce G.; Frey, Herbert V.; Kiefer, Walter S.; Nerem, R. Steven; Zuber, Maria T.

    1993-01-01

    New spherical harmonic models of the gravity and topography of Mars place important constraints on the structure and dynamics of the interior. The gravity and topography models are significantly phase coherent for harmonic degrees n less than 30 (wavelengths greater than 700 km). Loss of coherence below that wavelength is presumably due to inadequacies of the models, rather than a change in behavior of the planet. The gravity/topography admittance reveals two very different spectral domains: for n greater than 4, a simple Airy compensation model, with mean depth of 100 km, faithfully represents the observed pattern; for degrees 2 and 3, the effective compensation depths are 1400 and 550 km, respectively, strongly arguing for dynamic compensation at those wavelengths. The gravity model has been derived from a reanalysis of the tracking data for Mariner 9 and the Viking Orbiters, The topography model was derived by harmonic analysis of the USGS digital elevation model of Mars. Before comparing gravity and topography for internal structure inferences, we must ensure that both are consistently referenced to a hydrostatic datum. For the gravity, this involves removal of hydrostatic components of the even degree zonal coefficients. For the topography, it involves adding the degree 4 equipotential reference surface, to get spherically referenced values, and then subtracting the full degree 50 equipotential. Variance spectra and phase coherence of orthometric heights and gravity anomalies are addressed.

  13. The strength of contributions from topography mismatch and measurement filtering to simulated net ecosystem exchange in complex terrain

    NASA Astrophysics Data System (ADS)

    Brooks, B.; Desai, A. R.; Stephens, B. B.; Jacobson, A. R.

    2011-12-01

    Global scale carbon cycle inverse models provide invaluable information for the construction of empirically based carbon budgets based on in situ measurements. In landscapes of predominantly smooth topography inverse carbon cycle models are useful for diagnosing the magnitude and climate sensitivity of different regional carbon sinks. However, in landscapes of predominately complex topography inversion model results come with strong caveats for two reasons: 1) Coarse gridding of model topography can lead the model to sample observations at elevations far above the model surface, and 2) Transport wind fields over smoothed model representations of mountain regions are not always sufficiently resolved to inform the model about the source region for assimilated measurements. The uncertainty contributed by incorrect winds and topography mismatches (e.g., differences between the actual measurement elevation and model surface on the order of 1,000 m) is thought to be smaller for higher resolution regional inversion models (e.g., Gockede et al., 2010; Schuh et al. 2010), but these uncertainties are not well constrained for larger scale inversion systems (e.g., Peters et al., 2010), which are one of few ways for determining the relative priority of regional sinks. In this work we examine the effects on net ecosystem exchange (NEE) for a global scale inversion system when 1) topography mismatches are ameliorated, and 2) subset observations consistent with model resolution are used rather than observation-based subsets. Our focus is to use an example inversion model system, CarbonTracker (Peters et al., 2007; 2010), driven by CO2 mixing ratio measurements, including the RACCOON Network in the United States Mountain West (raccoon.ucar.edu), to quantify and compare the contribution to NEE from tower elevation mismatches and filtering strategies across biomes and and in terms of forecast skill (model data mismatch). We further compare our results to the differences in NEE over the same region from both inverse and forward models that participated in the North American Carbon Program Regional-Continental Model Synthesis.

  14. A method of calculating the total flow from a given sea surface topography

    NASA Technical Reports Server (NTRS)

    Rao, Desiraju B.; Steenrod, Stephen D.; Sanchez, Braulio V.

    1987-01-01

    Using a simple dynamical model of a wind-driven ocean circulation of the Stommel type, and an analytical basis developed to objectively analyze the sea surface height residuals from an altimeter and, in the process, to determine the total flow instead of just the near surface geostrophic component associated with the given sea surface topography. The method is based on first deriving the solution to the forced problem for a given wind stress required to develop a hypothetical true or perfect data field and to establishing the basis for the objective analysis. The stream function and the surface height field for the forced problem are developed in terms of certain characteristic functions with the same expansion coefficients for both fields. These characteristic functions are simply the solutions for a homogeneous elliptic equation for the stream function and the solutions of an inhomogeneous balance equation for the height field. For the objective analysis, using a sample of randomly selected height values from the true data field, the height field characteristic functions are used to fit the given topography in a least squares sense. The resulting expansion coefficients then permit the synthesis of the total flow field via the stream function characteristic modes and the solution is perfectly well behaved even along the equator. The method of solution is easily adaptable to realistic ocean basis by straight forward numerical methods. The analytical basis of the theory and the results for an ideal rectangular basin on a beta plane are described.

  15. Resolving the influences of climatology and topography on water isotopes

    NASA Astrophysics Data System (ADS)

    Auerbach, D. J.; Brandon, M. T.; Hren, M. T.

    2014-12-01

    Paleotopography records are critical to understanding geodynamic processes in ancient mountain ranges. The imprint of topography on stable isotopes of precipitation ("water isotopes") has become the most widely used method for reconstructing topography. Current approximations of how orographic lifting drives fractionation of water isotopes use 1D topography and a model based on either empirical observations or 1D Rayleigh fractionation. However, atmospheric physics tells us that the pattern and magnitude of lifting varies due to the shape of topography. We also know that the source of water isotopes and the local climatology (e.g., wind speed and direction, moist stability of the air) vary on both short and long time scales. Current approaches fail to separate the signal of topography from that of potentially large, short-term (<100 kyr) climate variations in water isotope records. We present an isotope-enabled version of the linear theory of orographic precipitation (LTOP) of Smith and Barstad (2004), which describes the response of water isotopes to topography. This model provides a first-order approximation of the water-isotope field produced by moist air flowing over complex 3D topography, which allows us to explore how the water isotope field is influenced by variations in climatology and topography. The LTOP model is attractive because of its simplicity: just 7 variables are used calculate the water isotope field, but the model still accounts for lateral flow and upwind phase tilting due to topographic barriers (to the non-linear limit). We tested this model in modern Patagonia, where there is a simple westerly pattern of atmospheric flow across a north-south mountain range. The model reproduces the strong observed fractionation and matches 166 field measurements of water isotopes in precipitation fairly well (R2 = 0.61). Sensitivity tests indicate the water isotope field is most sensitive to variations in the composition of source water (ocean), wind speed, and wind direction. Short-term climate variations are on the order of 16 ?D; isotope records showing less variability should be treated as unreliable. The capacity of the LTOP model to describe the observed complexity of atmospheric behavior in response to 3D topography is an important step towards future advances in paleotopography work.

  16. Button-pressing affects P300 amplitude and scalp topography

    PubMed Central

    Salisbury, Dean F.; Rutherford, Bret; Shenton, Martha E.; McCarley, Robert W.

    2009-01-01

    Background Scant and equivocal research exists examining the effects of button-pressing on P300. Button-pressing may decrease P300 latency and amplitude. The melding of motor potentials and P300 may also confound studies of P300 topography, such as studies of temporal scalp-area asymmetries in schizophrenia. Method P300 was measured on button-press and silent-count tasks in control subjects. An estimate of motor activity was constructed from a simple reaction time task, with reaction times matched to the button-press task. The motor estimate was subtracted from the button-press P300 to assess Koks (1988) additive model. Lastly, lateral P300 from schizophrenia patients was compared with each conditions P300. Results P300 was smaller and its topography different in the button-pressing task relative to silent-counting. The motor-correction procedure generated a P300 with normal topography. Comparison of the button-press P300 in controls to the silent-count P300 in schizophrenia patients reduced a significant lateral asymmetry to trend level. This asymmetry was significant after the correction procedure. Conclusions Button-pressing generates smaller P300 than silent-counting. Also, P300 topography in button-pressing tasks is confounded by motor potentials. The distortion can be corrected with a motor potential estimate. Motor potentials can occlude differences in P300 topography between groups. PMID:11514251

  17. Linear baroclinic instability in the presence of large scale topography

    NASA Technical Reports Server (NTRS)

    Reynolds, Nathaniel Dunton

    1987-01-01

    The effect of a planetary-scale, wavenumber 2 topography on baroclinically active disturbances is investigated for a channel domain in a two-layer, quasi-geostrophic context. When the lower-layer zonal velocity is nonzero, the topography influences the disturbances by forcing a stationary wave, and the topography and the forced wave influence the growth rates and the spatial structures of the time-dependent solutions. The case of zero zonal velocity in the lower layer was also investigated, for which no forced wave exists. Asymptotic forms of the equations, valid when the topographic effect (governed by the ratio of the nondimensional topographic height to the rotational Froude number) is small, are used to obtain both the stationary and time-dependent solutions. The latter are also obtained using a numerical approach, in which is determined the eigenvalues and eigenfunctions of a matrix representing the dynamical equations. Agreement is good between the two approaches. Recent laboratory experiments with a baroclinic annulus in which there is a false bottom with wavenumber 2 topography, are used to select governing parameters. The simultaneous presence of a stationary forced wave of wavenumber 2 and a time-dependent baroclinic wave of wavenumber 4, which has wavenumber 2 and 6 sidebands due to the topography, yields a flow field that exhibits some principal features of the laboratory experiments. The position of the forced wave and the location of an excursion in latitude of the storm track show qualitative resemblance to those features observed in the atmosphere.

  18. Static and dynamic support of western United States topography

    NASA Astrophysics Data System (ADS)

    Becker, Thorsten W.; Faccenna, Claudio; Humphreys, Eugene D.; Lowry, Anthony R.; Miller, Meghan S.

    2014-09-01

    Isostatic and dynamic models of Earth's surface topography can provide important insights into the driving processes of tectonic deformation. We analyze these two estimates for the tectonically-active western United States using refined structural models derived from EarthScope USArray. For the crust, use of recent Moho depth measurements and crustal density anomalies inferred from passive source seismology improve isostatic models. However, seismically determined lithospheric thickness variations from lithosphere-asthenosphere boundary (LAB) maps, and lithospheric and mantle density anomalies derived from heat flow or uppermost mantle tomography, do not improve isostatic models substantially. Perhaps this is a consequence of compositional heterogeneity, a mismatch between thermal and seismological LAB, and structural complexity caused by smaller-scale dynamics. The remaining, non-isostatic (dynamic) component of topography is large. Topography anomalies include negative residuals likely due to active subduction of the Juan de Fuca plate, and perhaps remnants of formerly active convergence further south along the margin. Our finding of broad-scale, positive residual topography in the Basin and Range substantiates previous results, implying the presence of anomalous buoyancy there which we cannot fully explain. The Colorado Plateau does not appear dynamically anomalous at present, except at its edges. Many of the residual topography features are consistent with predictions from mantle flow computations. This suggests a convective origin, and important interactions between vigorous upper mantle convection and intraplate deformation.

  19. Mercury's Thermal Evolution, Dynamical Topography and Geoid

    NASA Astrophysics Data System (ADS)

    Ziethe, Ruth; Benkhoff, Johannes

    Among the terrestrial planets Mercury is not only the smallest, but also the densest (after correction for self-compression). To explain Mercury's high density it is considered likely that the planet's mantle was removed during a giant impact event, when proto-Mercury was already differentiated into an iron core and a silicate mantle. Beside the damage to the planet's mantle the vaporization would cause a significant loss of volatile elements, leaving the remaining planet molten and dominated by extremely refractory material.Since the arrival of a spacecraft at the enigmatic planet is not to be expected before 2011 (Messenger) or 2019 (BepiColombo) we might already prepare ourselves for the upcoming results and perform tests that allow some anticipation of the measured data. The hermean mantle is modelled as an internally and bottom heated, isochemical fluid in a spherical shell. The principle of this convection model is widely accepted and is used for various models of thermal evolution of terrestrial planets, e.g., the Earth, Mars or the Moon. We are solving the hydrodynamical equations, derived from the conservation of mass, momentum and energy. A program originally written by S. Zhang is used to solve the temperature field which employs a combination of a spectral and a finite difference method. Beside the large core as a heat source 'from below' the decay of radioactive isotopes provides internal heating of the hermean mantle. The viscosity of the mantel material depends exponentially on the inverse temperature. The model results show the typical behaviour of a one-plate-planet, meaning the surface is not broken into several tectonic plates but the outside is a single rigid shell. The thermal evolution is generally charaterized by the growth of a massive lithosphere on top of the convecting mantle. The lower mantle and core cool comparatively little and stay at temperatures between 1900K and 2000K until about 2.0Ga after the simulation was started. The stagnant lid comprises roughly half the mantle after only 0.5Ga. Since the rigid lithosphere does not take part in the convection anymore, the heat coming from the interior (due to the cooling of the large core) can only be transported through the lithosphere by thermal conduction. This is a significantly less effective mechanism of heat transport than convection and hence the lithosphere forms an insulating layer. As a result, the interior is kept relatively warm.Because the mantle is relatively shallow compared to the planet's radius, and additionally the thick stagnant lid is formed relatively rapid, the convection is confined to a layer of only about 200km to 300km. Convection structures are therefore relatively small structured. The flow patterns in the early evolution show that mantle convection is characterized by numerous upwelling plumes, which are fed by the heat flow from the cooling core. These upwellings are relatively stable regarding their spatial position. As the core cools down the temperature anomalies become colder and less pronounced but not less numerous. In our calculations, a region of partial melt in the mantle forms immediately after the start of the model at a depths of roughly 220km. While in the entire lower mantle the temperature exceeds the solidus, the highest melt degrees can be found in the upwelling plumes. The partial molten region persists a significant time (up to 2.5Ga). How long the partial molten zone actually survives depends strongly on the initial conditions of the model. For instance, an outer layer with a reduced thermal conductivity would keep the lower mantle significantly warmer and a molten layer survives longer. The hot upwellings cause a surface deformation (dynamical topography) which itself causes a gravity anomaly. Due to the weak constraints of important parameters (e.g. sulfur content of the core, mantle rheology, amount and distribution of radiogenic heat sources, planetary contraction, thermal conductivity, etc) numerous models are required to understand the importance and influence of the mentioned variables.

  20. The global topography of Mars and implications for surface evolution.

    PubMed

    Smith, D E; Zuber, M T; Solomon, S C; Phillips, R J; Head, J W; Garvin, J B; Banerdt, W B; Muhleman, D O; Pettengill, G H; Neumann, G A; Lemoine, F G; Abshire, J B; Aharonson, O; Brown, C D; Hauck, S A; Ivanov, A B; McGovern, P J; Zwally, H J; Duxbury, T C

    1999-05-28

    Elevations measured by the Mars Orbiter Laser Altimeter have yielded a high-accuracy global map of the topography of Mars. Dominant features include the low northern hemisphere, the Tharsis province, and the Hellas impact basin. The northern hemisphere depression is primarily a long-wavelength effect that has been shaped by an internal mechanism. The topography of Tharsis consists of two broad rises. Material excavated from Hellas contributes to the high elevation of the southern hemisphere and to the scarp along the hemispheric boundary. The present topography has three major drainage centers, with the northern lowlands being the largest. The two polar cap volumes yield an upper limit of the present surface water inventory of 3.2 to 4.7 million cubic kilometers. PMID:10348732

  1. Sintered silver joints via controlled topography of electronic packaging subcomponents

    DOEpatents

    Wereszczak, Andrew A.

    2014-09-02

    Disclosed are sintered silver bonded electronic package subcomponents and methods for making the same. Embodiments of the sintered silver bonded EPSs include topography modification of one or more metal surfaces of semiconductor devices bonded together by the sintered silver joint. The sintered silver bonded EPSs include a first semiconductor device having a first metal surface, the first metal surface having a modified topography that has been chemically etched, grit blasted, uniaxial ground and/or grid sliced connected to a second semiconductor device which may also include a first metal surface with a modified topography, a silver plating layer on the first metal surface of the first semiconductor device and a silver plating layer on the first metal surface of the second semiconductor device and a sintered silver joint between the silver plating layers of the first and second semiconductor devices which bonds the first semiconductor device to the second semiconductor device.

  2. Topographies of plasma-hardened surfaces of poly(dimethylsiloxane)

    NASA Astrophysics Data System (ADS)

    Grrn, Patrick; Wagner, Sigurd

    2010-11-01

    We studied the formation of surface layers hardened by plasma-enhanced oxidation of the silicone elastomer poly(dimethylsiloxane). We explored the largest parameter space surveyed to date. The surface layers may wrinkle, crack, or both, under conditions that at times are controlled by design, but more often have been discovered by trial-and-error. We find four distinct topographies: flat/wrinkled/cracked/cracked and wrinkled. Each topography is clearly separated in the space of plasma dose versus plasma pressure. We analyzed wrinkle amplitude and wavelength by atomic force microscopy in the tapping mode. From these dimensions we calculated the elastic modulus and thickness of the hard surface layer, and inferred a graded hardness, by employing a modified theoretical model. Our main result is the identification of the parameters under which the technologically important pure wrinkled, crack-free topography is obtained.

  3. Implications of MOLA Global Roughness, Statistics, and Topography

    NASA Technical Reports Server (NTRS)

    Aharonson, O.; Zuber, M. T.; Neumann, G. A.

    1999-01-01

    New insights are emerging as the ongoing high-quality measurements of the Martian surface topography by Mars Orbiter Laser Altimeter (MOLA) on board the Mars Global Surveyor (MGS) spacecraft increase in coverage, resolution, and diversity. For the first time, a global characterization of the statistical properties of topography is possible. The data were collected during the aerobreaking hiatus, science phasing, and mapping orbits of MGS, and have a resolution of 300-400 m along track, a range resolution of 37.5 cm, a range precision of 1-10 m for surface slopes up to 30 deg., and an absolute accuracy of topography of 13 m. The spacecraft's orbit inclination dictates that nadir observations have latitude coverage of about 87.1S to 87.1N; the addition of observations obtained during a period of off-nadir pointing over the north pole extended coverage to 90N. Additional information is contained in the original extended abstract.

  4. A scanning radar altimeter for mapping continental topography

    NASA Technical Reports Server (NTRS)

    Dixon, T. H.

    1986-01-01

    Topographic information constitutes a fundamental data set for the Earth sciences. In the geological and geophysical sciences, topography combined with gravitational information provides an important constraint on the structure and rheologic properties of the crust and lithosphere. Detailed topography data can also be used to map offsets associated with faulting and to reveal the effects of tectonic deformation. In the polar regions, elevation data form a crucial but as yet largely unavailable resource for studying ice sheet mass balance and ice flow dynamics. The vast Antarctic ice sheet is the largest fresh water reservoir on Earth and is an important influence on ocean circulation and global climate. However, our knowledge of its stability is so limited that we cannot even specify whether the Antarctic ice sheet is growing or shrinking. It is clear that there is need for high quality global topography data. A summary of potential applications with their resolution requirements is shown.

  5. Crystal quality analysis and improvement using x-ray topography.

    SciTech Connect

    Maj, J.; Goetze, K.; Macrander, A.; Zhong, Y.; Huang, X.; Maj, L.; Univ. of Chicago

    2008-01-01

    The Topography X-ray Laboratory of the Advanced Photon Source (APS) at Argonne National Laboratory operates as a collaborative effort with APS users to produce high performance crystals for APS X-ray beamline experiments. For many years the topography laboratory has worked closely with an on-site optics shop to help ensure the production of crystals with the highest quality, most stress-free surface finish possible. It has been instrumental in evaluating and refining methods used to produce high quality crystals. Topographical analysis has shown to be an effective method to quantify and determine the distribution of stresses, to help identify methods that would mitigate the stresses and improve the Rocking curve, and to create CCD images of the crystal. This paper describes the topography process and offers methods for reducing crystal stresses in order to substantially improve the crystal optics.

  6. Topographies of plasma-hardened surfaces of poly(dimethylsiloxane)

    SciTech Connect

    Goerrn, Patrick; Wagner, Sigurd

    2010-11-15

    We studied the formation of surface layers hardened by plasma-enhanced oxidation of the silicone elastomer poly(dimethylsiloxane). We explored the largest parameter space surveyed to date. The surface layers may wrinkle, crack, or both, under conditions that at times are controlled by design, but more often have been discovered by trial-and-error. We find four distinct topographies: flat/wrinkled/cracked/cracked and wrinkled. Each topography is clearly separated in the space of plasma dose versus plasma pressure. We analyzed wrinkle amplitude and wavelength by atomic force microscopy in the tapping mode. From these dimensions we calculated the elastic modulus and thickness of the hard surface layer, and inferred a graded hardness, by employing a modified theoretical model. Our main result is the identification of the parameters under which the technologically important pure wrinkled, crack-free topography is obtained.

  7. Effect of topography on sulfate redistribution in Cumulonimbus cloud development.

    PubMed

    Vujovi?, Dragana; Vu?kovi?, Vladan; Curi?, Mla?en

    2014-03-01

    An aqueous chemical module is created and included into a complex three-dimensional atmospheric cloud-resolving mesoscale model. In the chemical module, oxidation of S(IV) by ozone and hydrogen peroxide in cloud-water and rainwater, as important process of the sulfate production is included. To examine the impact of topography on the sulfate redistribution in a clean and a polluted environment, the complex topography of Serbia is included in the model. Numerical simulations of an isolated summer Cumulonimbus cloud shows that thunderstorms generate very strong vertical sulfate redistribution from the planetary boundary layer to the upper troposphere. This redistribution is sensitive to cloud dynamics, while cloud microphysics and precipitation determine wet removal of the chemical species. In simulations with realistic topography, the chemical species are transported over larger distances close to the surface, while in the upper atmosphere, there is no difference compared to the simulations without topography. The sensitivity tests of cloud chemistry to the physical processes are made. Omission of nucleation and impact scavenging of aerosols in the model simulations shows that 75.8 and 62.5 % of total sulfur mass deposited in the base experiment for the clean and the polluted environment, respectively, is the result of other processes. Exclusion of oxidation accounted for 19.2 and 37.7 % of total sulfur deposited for clean and polluted environment. Ignoring the ice phase almost not change mass of deposited sulfur: there is an increase of 2.9 and 1.5 % for clean and polluted atmosphere, respectively. Real topography conditions affect the sulfate redistribution in the sense of greater possibilities of transport. Numerical simulations without real topography give an artificial increase of deposited sulfur mass of about 25-30 %. PMID:24243093

  8. Ulva linza zoospore sensitivity to systematic variation of surface topography

    NASA Astrophysics Data System (ADS)

    Sheats, Julian Taylor

    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.

  9. Switchable micropatterned surface topographies mediated by reversible shape memory.

    PubMed

    Turner, Sara A; Zhou, Jing; Sheiko, Sergei S; Ashby, Valerie Sheares

    2014-06-11

    Reversibly switching topography on micrometer length scales greatly expands the functionality of stimuli-responsive substrates. Here we report the first usage of reversible shape memory for the actuation of two-way transitions between microscopically patterned substrates, resulting in corresponding modulations of the wetting properties. Reversible switching of the surface topography is achieved through partial melting and recrystallization of a semi-crystalline polyester embossed with microscopic features. This behavior is monitored with atomic force microscopy (AFM) and contact angle measurements. We demonstrate that the magnitude of the contact angle variations depends on the embossment pattern. PMID:24824729

  10. Sound propagation over uneven ground and irregular topography

    NASA Technical Reports Server (NTRS)

    Berthelot, Yves H.; Pierce, Allan D.; Kearns, James A.; Zhou, Ji-Xun

    1988-01-01

    Theoretical, computational, and experimental techniques were developed for predicting the effects of irregular topography on long range sound propagation in the atmosphere. Irregular topography is understood to imply a ground surface that: (1) is not idealizable as being perfectly flat, or (2) that is not idealizable as having a constant specific acoustic impedance. The focus is on circumstances where the propagation is similar to what might be expected for noise from low altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence.

  11. Venus gravity anomalies and their correlations with topography

    NASA Technical Reports Server (NTRS)

    Sjogren, W. L.; Bills, B. G.; Birkeland, P. W.; Esposito, P. B.; Konopliv, A. R.; Mottinger, N. A.; Ritke, S. J.; Phillips, R. J.

    1983-01-01

    This report provides a summary of the high-resolution gravity data obtained from the Pioneer Venus Orbiter radio tracking data. Gravity maps, covering a 70 deg latitude band through 360 deg of longitude, are displayed as line-of-sight and vertical gravity. Topography converted to gravity and Bouguer gravity maps are also shown in both systems. Topography to gravity ratios are made over several regions of the planet. There are markedly different ratios for the Aphrodite area as compared to the Beta and Atla areas.

  12. Sound propagation over uneven ground and irregular topography

    NASA Technical Reports Server (NTRS)

    Berthelot, Yves H.; Pierce, Allan D.; Main, Geoffrey L.; Zhou, Ji-Xun; Kearns, James A.

    1988-01-01

    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 is understood to imply a ground surface that is not idealizable as being perfectly flat or that is no idealizable as having a constant specific acoustic impedance. The focus is on circumstances where the propagation is similar to what might be expected for noise from low-altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence.

  13. Topography aware DFM rule based scoring for silicon yield modeling

    NASA Astrophysics Data System (ADS)

    Tripathi, Vikas; Katakamsetty, Ushasree; Yeo, Sky; Hui, Colin

    2015-03-01

    DFM rule based scoring is associated with manufacturability rules checking and applying the scoring to predict the yield entitlement for an IC chip design. Achieving high DFM score is one of the key requirements to get high yield. The DFM scoring methodology is currently limited to DFM recommend rules and their associated failure rates. In contrast to failure mechanism, chemical-mechanical polishing (CMP) step topography variations places an important role to it. In this paper, we present an advanced DFM analysis flow to compute DFM score that incorporate topography variation along with recommend rule scoring using complex scoring model to increase silicon yield correlation.

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    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.

  15. Influence of surface topography on the multilayer film formation

    SciTech Connect

    Grishchenko, Yu. V.; Zanaveskin, M. L.; Tolstikhina, A. L.

    2010-01-15

    The relationship between the topography of substrates and multilayer films deposited on these substrates (which are used in ring laser gyroscopes) has been investigated. The surfaces were studied by atomic-force microscopy. The statistical properties of the surface topography are analyzed within the approach based on a comparative analysis of the power spectral density functions of roughness calculated for the substrate and film. The degree of correlation between the substrate nanotopography and multilayer film is determined, and the influence of the substrate roughness on the optical characteristics of the deposited mirrors is established.

  16. Sound propagation over uneven ground and irregular topography

    NASA Technical Reports Server (NTRS)

    Kearns, J. A.; Pierce, A. D.; Main, G. L.

    1986-01-01

    Theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere was developed. Irregular topography here is understood to imply a ground surface that is not idealized as being perfectly flat or that is not idealized as having a constant specific acoustic impedance. The interest focuses on circumstances where the propagation is similar to what might be expected for noise from low altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence.

  17. Sound propagation over uneven ground and irregular topography

    NASA Technical Reports Server (NTRS)

    Pierce, A. D.; Main, G. L.; Kearns, J. A.; Benator, D. R.; Parish, J. R., Jr.

    1986-01-01

    The development of theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere is discussed. Irregular topography here is understood to imply a ground surface that (1) is not idealizable as being perfectly flat or (2) that is not idealizable as having a constant specific acoustic impedance. The study focuses on circumstances where the propagation is similar to what might be expected for noise from low-altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence.

  18. EAARL topography-Potato Creek watershed, Georgia, 2010

    USGS Publications Warehouse

    Bonisteel-Cormier, J.M.; Nayegandhi, Amar; Fredericks, Xan; Jones, J.W.; Wright, C.W.; Brock, J.C.; Nagle, D.B.

    2011-01-01

    This DVD contains lidar-derived first-surface (FS) and bare-earth (BE) topography GIS datasets of a portion of the Potato Creek watershed in the Apalachicola-Chattahoochee-Flint River basin, Georgia. These datasets were acquired on February 27, 2010.

  19. Oral Streptococci Biofilm Formation on Different Implant Surface Topographies

    PubMed Central

    Pita, Pedro Paulo Cardoso; Rodrigues, Jos Augusto; Ota-Tsuzuki, Claudia; Miato, Tatiane Ferreira; Zenobio, Elton G.; Giro, Gabriela; Figueiredo, Luciene C.; Gonalves, Cristiane; Gehrke, Sergio A.; Cassoni, Alessandra; Shibli, Jamil Awad

    2015-01-01

    The establishment of the subgingival microbiota is dependent on successive colonization of the implant surface by bacterial species. Different implant surface topographies could influence the bacterial adsorption and therefore jeopardize the implant survival. This study evaluated the biofilm formation capacity of five oral streptococci species on two titanium surface topographies. In vitro biofilm formation was induced on 30 titanium discs divided in two groups: sandblasted acid-etched (SAE- n = 15) and as-machined (M- n = 15) surface. The specimens were immersed in sterilized whole human unstimulated saliva and then in fresh bacterial culture with five oral streptococci species: Streptococcus sanguinis, Streptococcus salivarius, Streptococcus mutans, Streptococcus sobrinus, and Streptococcus cricetus. The specimens were fixed and stained and the adsorbed dye was measured. Surface characterization was performed by atomic force and scanning electron microscopy. Surface and microbiologic data were analyzed by Student's t-test and two-way ANOVA, respectively (P < 0.05). S. cricetus, S. mutans, and S. sobrinus exhibited higher biofilm formation and no differences were observed between surfaces analyzed within each species (P > 0.05). S. sanguinis exhibited similar behavior to form biofilm on both implant surface topographies, while S. salivarius showed the lowest ability to form biofilm. It was concluded that biofilm formation on titanium surfaces depends on surface topography and species involved. PMID:26273590

  20. Analysis of Multiple Manding Topographies during Functional Communication Training

    ERIC Educational Resources Information Center

    Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Winborn-Kemmerer, Lisa; Lee, John F.; Ibrahimovic, Muska

    2009-01-01

    We evaluated the effects of reinforcing multiple manding topographies during functional communication training (FCT) to decrease problem behavior for three preschool-age children. During Phase 1, a functional analysis identified conditions that maintained problem behavior for each child. During Phase 2, the children's parents taught them to

  1. Payload topography camera of Chang'e-3

    NASA Astrophysics Data System (ADS)

    Yu, Guo-Bin; Liu, En-Hai; Zhao, Ru-Jin; Zhong, Jie; Zhou, Xiang-Dong; Zhou, Wu-Lin; Wang, Jin; Chen, Yuan-Pei; Hao, Yong-Jie

    2015-11-01

    Chang'e-3 was China's first soft-landing lunar probe that achieved a successful roving exploration on the Moon. A topography camera functioning as the lander's “eye” was one of the main scientific payloads installed on the lander. It was composed of a camera probe, an electronic component that performed image compression, and a cable assembly. Its exploration mission was to obtain optical images of the lunar topography in the landing zone for investigation and research. It also observed rover movement on the lunar surface and finished taking pictures of the lander and rover. After starting up successfully, the topography camera obtained static images and video of rover movement from different directions, 360° panoramic pictures of the lunar surface around the lander from multiple angles, and numerous pictures of the Earth. All images of the rover, lunar surface, and the Earth were clear, and those of the Chinese national flag were recorded in true color. This paper describes the exploration mission, system design, working principle, quality assessment of image compression, and color correction of the topography camera. Finally, test results from the lunar surface are provided to serve as a reference for scientific data processing and application.

  2. Recent advances in engineering topography mediated antibacterial surfaces

    PubMed Central

    Hasan, Jafar

    2015-01-01

    The tendency of bacterial cells to adhere and colonize a material surface leading to biofilm formation is a fundamental challenge underlying many different applications including microbial infections associated with biomedical devices and products. Although, bacterial attachment to surfaces has been extensively studied in the past, the effect of surface topography on bacteria–material interactions has received little attention until more recently. We review the recent progress in surface topography based approaches for engineering antibacterial surfaces. Biomimicry of antibacterial surfaces in nature is a popular strategy. Whereas earlier endeavors in the field aimed at minimizing cell attachment, more recent efforts have focused on developing bactericidal surfaces. However, not all such topography mediated bactericidal surfaces are necessarily cytocompatible thus underscoring the need for continued efforts for research in this area for developing antibacterial and yet cytocompatible surfaces for use in implantable biomedical applications. This mini-review provides a brief overview of the current strategies and challenges in the emerging field of topography mediated antibacterial surfaces. PMID:26372264

  3. Recent advances in engineering topography mediated antibacterial surfaces.

    PubMed

    Hasan, Jafar; Chatterjee, Kaushik

    2015-10-14

    The tendency of bacterial cells to adhere and colonize a material surface leading to biofilm formation is a fundamental challenge underlying many different applications including microbial infections associated with biomedical devices and products. Although, bacterial attachment to surfaces has been extensively studied in the past, the effect of surface topography on bacteria-material interactions has received little attention until more recently. We review the recent progress in surface topography based approaches for engineering antibacterial surfaces. Biomimicry of antibacterial surfaces in nature is a popular strategy. Whereas earlier endeavors in the field aimed at minimizing cell attachment, more recent efforts have focused on developing bactericidal surfaces. However, not all such topography mediated bactericidal surfaces are necessarily cytocompatible thus underscoring the need for continued efforts for research in this area for developing antibacterial and yet cytocompatible surfaces for use in implantable biomedical applications. This mini-review provides a brief overview of the current strategies and challenges in the emerging field of topography mediated antibacterial surfaces. PMID:26372264

  4. Tectonic velocities, dynamic topography, and relative sea level

    NASA Astrophysics Data System (ADS)

    Husson, L.; Conrad, C. P.

    2006-12-01

    The competition between ocean volume and dynamic topography in response to variable tectonic velocities can be captured by a simple, yet dynamically consistent, analysis based on the boundary layer theory. Our model reveals that short-lived changes in plate velocity (""tectonic pulses") have a negligible impact on dynamic topography. Tectonic velocities essentially mirror variations in mantle viscosity, but are not indicative of substantial modification of dynamic topography, which primarily reflects mass anomalies in the mantle. This implies that relative sea level is unlikely to be affected by "tectonic pulses" and also that observed tilting of cratonic margins couldn't result from a pulse of increased tectonic velocities. Thus, relative sea level is primarily controlled by the seafloor age distribution, although long-term (>100 myrs) changes in tectonic velocity will produce dynamic topography that reinforces sea level changes associated with changing ridge volume. These results can be related to present day plate motion and trench migration and mantle flow inferred from mantle tomography, in order to characterize the current variation -either dynamic or isostatic- of the volume of the oceans.

  5. Short wavelength topography on the inner-core boundary

    PubMed Central

    Cao, Aimin; Masson, Yder; Romanowicz, Barbara

    2007-01-01

    Constraining the topography of the inner-core boundary is important for studies of coremantle 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 ?0.10.15 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

  6. Dental topography of platyrrhines and prosimians: convergence and contrasts.

    PubMed

    Winchester, Julia M; Boyer, Doug M; St Clair, Elizabeth M; Gosselin-Ildari, Ashley D; Cooke, Siobhn B; Ledogar, Justin A

    2014-01-01

    Dental topographic analysis is the quantitative assessment of shape of three-dimensional models of tooth crowns and component features. Molar topographic curvature, relief, and complexity correlate with aspects of feeding behavior in certain living primates, and have been employed to investigate dietary ecology in extant and extinct primate species. This study investigates whether dental topography correlates with diet among a diverse sample of living platyrrhines, and compares platyrrhine topography with that of prosimians. We sampled 111 lower second molars of 11 platyrrhine genera and 121 of 20 prosimian genera. For each tooth we calculated Dirichlet normal energy (DNE), relief index (RFI), and orientation patch count (OPCR), quantifying surface curvature, relief, and complexity respectively. Shearing ratios and quotients were also measured. Statistical analyses partitioned effects of diet and taxon on topography in platyrrhines alone and relative to prosimians. Discriminant function analyses assessed predictive diet models. Results indicate that platyrrhine dental topography correlates to dietary preference, and platyrrhine-only predictive models yield high rates of accuracy. The same is true for prosimians. Topographic variance is broadly similar among platyrrhines and prosimians. One exception is that platyrrhines display higher average relief and lower relief variance, possibly related to lower relative molar size and functional links between relief and tooth longevity distinct from curvature or complexity. Explicitly incorporating phylogenetic distance matrices into statistical analyses of the combined platyrrhine-prosimian sample results in loss of significance of dietary effects for OPCR and SQ, while greatly increasing dietary significance of RFI. PMID:24318939

  7. Role of Cigarette Sensory Cues in Modifying Puffing Topography

    PubMed Central

    Rees, Vaughan W.; Kreslake, Jennifer M.; Wayne, Geoffrey Ferris; O Connor, Richard J.; Cummings, K. Michael; Connolly, Gregory N.

    2012-01-01

    Background Human puffing topography promotes tobacco dependence by ensuring nicotine delivery, but the factors that determine puffing behavior are not well explained by existing models. Chemosensory cues generated by variations in cigarette product design features may serve as conditioned cues to allow the smoker to optimize nicotine delivery by adjusting puffing topography. Internal tobacco industry research documents were reviewed to understand the influence of sensory cues on puffing topography, and to examine how the tobacco industry has designed cigarettes, including modified risk tobacco products (MRTPs), to enhance puffing behavior to optimize nicotine delivery and product acceptability. Methods Relevant internal tobacco industry documents were identified using systematic searching with key search terms and phrases, and then snowball sampling method was applied to establish further search terms. Results Modern cigarettes are designed by cigarette manufacturers to provide sensory characteristics that not only maintain appeal, but provide cues which inform puffing intensity. Alterations in the chemosensory cues provided in tobacco smoke play an important role in modifying smoking behavior independently of the central effects of nicotine. Conclusions An associative learning model is proposed to explain the influence of chemosensory cues on variation in puffing topography. These cues are delivered via tobacco smoke and are moderated by design features and additives used in cigarettes. The implications for regulation of design features of modified risk tobacco products, which may act to promote intensive puffing while lowering risk perceptions, are discussed. PMID:22365895

  8. Product layout induced topography effects on intrafield levelling

    NASA Astrophysics Data System (ADS)

    Simiz, J.-G.; Hasan, T.; Staals, F.; Le-Gratiet, B.; Tel, W. T.; Prentice, C.; Tishchenko, A.

    2015-09-01

    With continuing dimension shrinkage using the TWINSCAN NXT:1950i scanner on the 28nm node and beyond, the imaging depth of focus (DOF) becomes more critical. Focus budget breakdown studies [Ref 2, 5] show that even though the intrafield component stays the same, it becomes a larger relative percentage of the overall DOF. Process induced topography along with reduced Process Window can lead to yield limitations and defectivity issues on the wafer. In a previous paper, the feasibility of anticipating the scanner levelling measurements (Level Sensor, Agile and Topography) has been shown [1]. This model, built using a multiple variable analysis (PLS: Partial Least Square regression) and GDS densities at different layers showed prediction capabilities of the scanner topography readings up to 0.78 Q² (the equivalent of R² for expected prediction). Using this model, care areas can be defined as parts of the field that cannot be seen nor corrected by the scanner, which can lead to local DOF shrinkage and printing issues. This paper will investigate the link between the care areas and the intrafield focus that can be seen at the wafer level, using offline topography measurements as a reference. Some improvements made on the model are also presented.

  9. Recent advances in engineering topography mediated antibacterial surfaces

    NASA Astrophysics Data System (ADS)

    Hasan, Jafar; Chatterjee, Kaushik

    2015-09-01

    The tendency of bacterial cells to adhere and colonize a material surface leading to biofilm formation is a fundamental challenge underlying many different applications including microbial infections associated with biomedical devices and products. Although, bacterial attachment to surfaces has been extensively studied in the past, the effect of surface topography on bacteria-material interactions has received little attention until more recently. We review the recent progress in surface topography based approaches for engineering antibacterial surfaces. Biomimicry of antibacterial surfaces in nature is a popular strategy. Whereas earlier endeavors in the field aimed at minimizing cell attachment, more recent efforts have focused on developing bactericidal surfaces. However, not all such topography mediated bactericidal surfaces are necessarily cytocompatible thus underscoring the need for continued efforts for research in this area for developing antibacterial and yet cytocompatible surfaces for use in implantable biomedical applications. This mini-review provides a brief overview of the current strategies and challenges in the emerging field of topography mediated antibacterial surfaces.

  10. Analysis of Multiple Manding Topographies during Functional Communication Training

    ERIC Educational Resources Information Center

    Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Winborn-Kemmerer, Lisa; Lee, John F.; Ibrahimovic, Muska

    2009-01-01

    We evaluated the effects of reinforcing multiple manding topographies during functional communication training (FCT) to decrease problem behavior for three preschool-age children. During Phase 1, a functional analysis identified conditions that maintained problem behavior for each child. During Phase 2, the children's parents taught them to…

  11. Stress distribution and topography of Tellus Regio, Venus

    NASA Technical Reports Server (NTRS)

    Williams, David R.; Greeley, Ronald

    1989-01-01

    The Tellus Regio area of Venus represents a subset of a narrow latitude band where Pioneer Venus Orbiter (PVO) altimetry data, line-of-sight (LOS) gravity data, and Venera 15/16 radar images have all been obtained with good resolution. Tellus Regio also has a wide variety of surface morphologic features, elevations ranging up to 2.5 km, and a relatively low LOS gravity anomaly. This area was therefore chosen in order to examine the theoretical stress distributions resulting from various models of compensation of the observed topography. These surface stress distributions are then compared with the surface morphology revealed in the Venera 15/16 radar images. Conclusions drawn from these comparisons will enable constraints to be put on various tectonic parameters relevant to Tellus Regio. The stress distribution is calculated as a function of the topography, the equipotential anomaly, and the assumed model parameters. The topography data is obtained from the PVO altimetry. The equipotential anomaly is estimated from the PVO LOS gravity data. The PVO LOS gravity represents the spacecraft accelerations due to mass anomalies within the planet. These accelerations are measured at various altitudes and angles to the local vertical and therefore do not lend themselves to a straightforward conversion. A minimum variance estimator of the LOS gravity data is calculated, taking into account the various spacecraft altitudes and LOS angles and using the measured PVO topography as an a priori constraint. This results in an estimated equivalent surface mass distribution, from which the equipotential anomaly is determined.

  12. Residual topography and lithospheric structure of the Antarctic continent

    NASA Astrophysics Data System (ADS)

    Molinari, I.; Baranov, A.; Danesi, S.; Morelli, A.

    2012-12-01

    Antarctica has been the subject of considerable interest in the past few years, following the International Polar Year. The structure of its crust at a continental scale is however still known with large uncertainty. A new Moho depth map for the Antarctic continent has been recently assembled (AntMoho), merging copious information from geophysical and geological studies selected from the literature. A large volume of old and new data has been analyzed: mostly seismic experiments, as well as receiver functions and geological studies, ranging from DSS profiles acquired by Soviet Union field experiments, to recent seismic receiver function studies. AntMoho has a reference lateral resolution of 1 degree. 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. Residual topography is obtained by removing the isostatic contribution of the crust from the observed topography. Long-wavelength residual topography is interpreted as dynamic response to large scale mantle convection and density contrasts. Our calculations show that significantly different inferences on lithospheric structure and mantle dynamics may result from the variance in Moho depth recorded in the different models. A better knowledge of Moho depth and, more generally, crustal structure for Antarctica at a continent scale is a goal with likely consequences for better understanding of the complex dynamic processes acting at a regional scale.

  13. Moire Topography For The Detection Of Orthopaedic Defects

    NASA Astrophysics Data System (ADS)

    Kamal, Syed A.; Lindseth, Richard E.

    1981-02-01

    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.

  14. Coupled Evolution of Topography and Orographic Precipitation in Varied Climates

    NASA Astrophysics Data System (ADS)

    Anders, A. M.

    2006-12-01

    Landscapes respond to climate change. However, even in the absence of external drivers of climate change, topography and regional climate evolve together over timescales of thousands to millions of years. Topography itself is a strong control on precipitation patterns and produces persistent precipitation gradients of 150-500 percent over spatial scales of 5-30 km. As precipitation fundamentally affects the ability of rivers and glaciers to erode, these same precipitation gradients directly influence topographic development. A coupled model of landscape evolution and orographic precipitation is used to explore the co-evolution of climate and topography under a range of climatic conditions. The CASCADE landscape evolution model simulates fluvial erosion with a threshold slope condition over a uniformly uplifting surface. An orographic precipitation model simulates flow over topography and the production and advection of precipitation particles. The delay time (timescale for advection of precipitation from its formation until it reaches the land surface) is a strong control on the steady-state landscape form produced by the coupled model. Delay time controls the peak elevation, hypsometric integral, channel concavity and ridge-valley relief in modeled landscapes. These results indicate that in addition to the clear impact of precipitation amounts on topography, spatial patterns of precipitation - which are controlled by delay time - also strongly influence topography. The delay time can be interpreted to represent the temperature of the region. Short delay times are consistent with fast-falling rain and a warm climate. Long delay times are consistent with climates in which precipitation falls more slowly, as snow, for a large portion of its descent. Thus, large differences in peak elevation, hypsometry, channel concavity and ridge-valley relief are predicted in different climatic settings. Moreover, a transition from a snow-dominated to a rain-dominated climate is predicted to increase peak elevation and channel concavity. This behavior is simply due to a shift in the spatial pattern of precipitation and lacks consideration of a transition from fluvial to glacial erosion. Further research is needed to refine understanding of the impact of spatial patterns of precipitation on landscape evolution, but initial results demonstrate that spatial variability in precipitation and its relationship to topography has a strong impact on both mountain geomorphology and moutain climates.

  15. Seismic waveform inversion for core-mantle boundary topography

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  16. Shape and topography corrections for planetary nuclear spectroscopy

    NASA Astrophysics Data System (ADS)

    Prettyman, Thomas H.; Hendricks, John S.

    2015-11-01

    The elemental composition of planetary surfaces can be determined using gamma ray and neutron spectroscopy. Most planetary bodies for which nuclear spectroscopy data have been acquired are round, and simple, analytic corrections for measurement geometry can be applied; however, recent measurements of the irregular asteroid 4 Vesta by Dawn required more detailed corrections using a shape model (Prettyman et al., Science 2012). In addition, subtle artifacts of topography have been observed in low altitude measurements of lunar craters, with potential implications for polar hydrogen content (Eke et al., JGR 2015). To explore shape and topography effects, we have updated the general-purpose Monte Carlo radiation transport code MCNPX to include a polygonal shape model (Prettyman and Hendricks, LPSC 2015). The shape model is fully integrated with the code’s 3D combinatorial geometry modules. A voxel-based acceleration algorithm enables fast ray-intersection calculations needed for Monte Carlo. As modified, MCNPX can model neutron and gamma ray transport within natural surfaces using global and/or regional shape/topography data (e.g. from photogrammetry and laser altimetry). We are using MCNPX to explore the effect of small-scale roughness, regional-, and global-topography for asteroids, comets and close-up measurements of high-relief features on larger bodies, such as the lunar surface. MCNPX can characterize basic effects on measurements by an orbiting spectrometer such as 1) the angular distribution of emitted particles, 2) shielding of galactic cosmic rays by surrounding terrain and 3) re-entrant scattering. In some cases, re-entrant scattering can be ignored, leading to a fast ray-tracing model that treats effects 1 and 2. The algorithm is applied to forward modeling and spatial deconvolution of epithermal neutron data acquired at Vesta. Analyses of shape/topography effects and correction strategies are presented for Vesta, selected small bodies and cratered planetary surfaces.

  17. Allometric scaling of infraorbital surface topography in Homo.

    PubMed

    Maddux, Scott D; Franciscus, Robert G

    2009-02-01

    Infraorbital morphology is often included in phylogenetic and functional analyses of Homo. The inclusion of distinct infraorbital configurations, such as the "canine fossa" in Homo sapiens or the "inflated" maxilla in Neandertals, is generally based on either descriptive or qualitative assessments of this morphology, or simple linear chord and subtense measurements. However, the complex curvilinear surface of the infraorbital region has proven difficult to quantify through these traditional methods. In this study, we assess infraorbital shape and its potential allometric scaling in fossil Homo (n=18) and recent humans (n=110) with a geometric morphometric method well-suited for quantifying complex surface topographies. Our results indicate that important aspects of infraorbital shape are correlated with overall infraorbital size across Homo. Specifically, individuals with larger infraorbital areas tend to exhibit relatively flatter infraorbital surface topographies, taller and narrower infraorbital areas, sloped inferior orbital rims, anteroinferiorly oriented maxillary body facies, posteroinferiorly oriented maxillary processes of the zygomatic, and non-everted lateral nasal margins. In contrast, individuals with smaller infraorbital regions generally exhibit relatively depressed surface topographies, shorter and wider infraorbital areas, projecting inferior orbital rims, posteroinferiorly oriented maxillary body facies, anteroinferiorly oriented maxillary processes, and everted lateral nasal margins. These contrasts form a continuum and only appear dichotomized at the ends of the infraorbital size spectrum. In light of these results, we question the utility of incorporating traditionally polarized infraorbital morphologies in phylogenetic and functional analyses without due consideration of continuous infraorbital and facial size variation in Homo. We conclude that the essentially flat infraorbital surface topography of Neandertals is not unique and can be explained, in part, as a function of possessing large infraorbital regions, the ancestral condition for Homo. Furthermore, it appears likely that the diminutive infraorbital region of anatomically modern Homo sapiens is a primary derived trait, with related features such as depressed infraorbital surface topography expressed as correlated secondary characters. PMID:19118866

  18. The effects of abrupt topography on plankton dynamics.

    PubMed

    Zavala Sansón, L; Provenzale, A

    2009-12-01

    Plankton population dynamics in the upper layer of the ocean depends on upwelling processes that bring nutrients from deeper waters. In turn, these depend on the structure of the vertical velocity field. In coastal areas and in oceanic regions characterized by the presence of strong submarine topographic features, the variable bottom topography induces significant effects on vertical velocities and upwelling/downwelling patterns. As a consequence, large plankton and fish abundances are frequently observed above seamounts, canyons and steep continental shelves. In this work, the dynamics of an NPZ (nutrient-phytoplankton-zooplankton) system is numerically studied by coupling the ecosystem model with a quasi two-dimensional (2D) fluid model with topography. At variance with classical 2D approaches, this formulation allows for an explicit expression of the vertical motions produced when fluid columns are squeezed and stretched as they experience changes of depth. Thus, input or output of nutrients at the surface are associated with fluid motion over the bottom topography. We examine the dynamics of a cyclonic vortex over two basic topographies: a steep escarpment and a submarine mountain. We show that plankton abundance over the escarpment is modulated by the passing of topographic Rossby waves, generated by the vortex-topography interaction. In such configuration, advection effects driven by the flow over the escarpment are of limited relevance for the dynamics of biological fields. By contrast, we find that the flow resulting from the interaction of a vortex with a seamount is sufficiently strong and persistent to allow for a remarkable increase of nutrients, and a corresponding enhancement of phytoplankton and zooplankton concentrations. Over the seamount, advection effects associated with trapped flow perturbations around the summit play an essential role. PMID:19737575

  19. Comparison of SRTM Topography to USGS and High Resolution Laser Altimetry Topography: Case Studies From the Oregon Coast Range

    NASA Astrophysics Data System (ADS)

    Dietrich, W. E.; Stock, J. D.; Allen, D.; Beluggi, D.; Montgomery, D. R.; Roering, J. J.

    2001-12-01

    The Shuttle Radar Topography mission (SRTM) acquired topographic data for the non-polar regions of earth at a nominal 30-m resolution. This horizontal resolution is dramatically higher than previous ~1 km data, and is likely to be used by a broad cross-section of the earth sciences community for detailed modeling of surface and coupled surface-atmospheric models. These users will need to know how SRTM topography compares with field-scale (e.g., 1-2 m) topography. We compare SRTM 30-m data to 3 sites in the forested steeplands of the Oregon Coast Range where we have acquired 2-3 m spaced topography using laser altimetry and total station surveys over areas from 2-6 km2. At each site, we have field-checked the laser altimetry with ground reconnaissance and measurements, and have identified vegetation cover. In addition, we compare the SRTM data to the existing public access data from the USGS 10- and 30-m data. We compare the coarser resolution data to high resolution data, and to re-gridded versions of the high resolution data for the following landscape metrics: 1) mean slope, 2) local slope distribution, 3) drainage density at a given area threshold, 4) relief as a function of area, 5) link magnitude distribution, and 6) slope versus area for the valley network. We also compare individual hillslope and river profiles by comparing rms error of the coarser data to fine resolution topography, and evaluate the planform errors in the coarser valley network. Our comparisons should guide user's interpretation of SRTM data where ground-truthing data are absent.

  20. Controls of climate, topography, vegetation and lithology on drainage density extracted from high resolution topography

    NASA Astrophysics Data System (ADS)

    Sangireddy, H.; Carothers, R. A.; Passalacqua, P.; Stark, C. P.

    2014-12-01

    Drainage density is a useful topographic metric that varies as a function of geomorphic processes and that serves to quantify links with topography, climate, vegetation, and lithology. Here we analyze 101 sub-basins across thirteen states in the USA using high-resolution digital terrain models (DTMs) in combination with data on the spatial variation of precipitation, soil, geology, and land cover. We test the following hypotheses: (1) Drainage density carries strong, codependent signatures of rainfall variability, soil type, and topographic relief; (2) Drainage density reflects the extent of landscape dissection on the sub-catchment scale and the subsequent processes of vegetation recovery and gullying.We employ a dimensionless drainage density (Ddd) metric defined as the ratio of likely channelized pixels in a basin to its total number of pixels, and map this metric across meter-resolution lidar DTMs using GeoNet [Passalacqua et al., 2010]. We assess the resolution-dependent scaling of Ddd and observe that it is a much weaker scaling function of DTM resolution than the dimensional formulation of drainage density (Dg), which is classically defined as the ratio of total channel length to total basin area.In order to characterize the correlation structure of drainage density with climatic parameters such as mean annual precipitation (MAP), we use a Gaussian mixture model and identify two sub-groups of landscapes that display different correlations. We observe that Ddd and MAP are negatively correlated in arid and semi-arid environments and positively correlated in humid environments. The transition occurs at a MAP around 900-1000mm/yr and coincides with the maximum observed values of soil thickness and available water content. Landscape relief has a negative correlation with Ddd in arid environments while the correlation is positive in humid climates. We discuss the implication of our results for understanding eco-geomorphic processes and for modeling landscape evolution.References:Passalacqua, P., Do Trung, T., Foufoula-Georgiou, E., Sapiro, G., & Dietrich, W. E. (2010). A geometric framework for channel network extraction from lidar: Nonlinear diffusion and geodesic paths. Journal of Geophysical Research: Earth Surface (2003-2012), 115(F1).

  1. High Resolution Global Topography of Eros from NEAR Imaging and LIDAR Data

    NASA Technical Reports Server (NTRS)

    Gaskell, Robert W.; Konopliv, A.; Barnouin-Jha, O.; Scheeres, D.

    2006-01-01

    Principal Data Products: Ensemble of L-maps from SPC, Spacecraft state, Asteroid pole and rotation. Secondary Products: Global topography model, inertia tensor, gravity. Composite high resolution topography. Three dimensional image maps.

  2. Corneal topography in the study of astigmatic excimer laser ablation

    NASA Astrophysics Data System (ADS)

    McDonnell, Peter J.

    1992-08-01

    Corneal astigmatism, both naturally occurring and iatrogenically induced, is a commonly encountered problem. Examination of corneal topography with instruments that digitize reflected ring images and calculate corneal geometry suggests that corneal astigmatism often deviates from spherocylindrical optics; the observed topography may be highly asymmetrical about the center of the pupil. Currently used incisional procedures are limited in terms of predictability of surgical outcome. The 193 nm excimer laser can be used to alter anterior corneal curvature and flatten the cornea to correct myopia. For correction of astigmatism, a slit-opening in the laser delivery system can be used to selectively flatten the steep meridian. Early results using this procedure for correction of iatrogenically induced high corneal astigmatism are promising. A nationwide multicenter clinical trial is now underway in the United States to evaluate this technique for the correction of naturally occurring astigmatism and compound myopic astigmatism.

  3. Irregular topography at the Earth's inner core boundary.

    PubMed

    Dai, Zhiyang; Wang, Wei; Wen, Lianxing

    2012-05-15

    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 2.5s) 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 14km changing within a lateral distance of no more than 6km, and a height variation of 4-8km with a lateral length scale of 2-4km. 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

  4. Crustal thinning and topography at passive continental margins

    NASA Astrophysics Data System (ADS)

    Terje Osmundsen, Per; Redfield, Thomas F.; Ebbing, Jrg

    2010-05-01

    There is a relationship between crustal thinning patterns and onshore topography at passive continental margins. This relationship appears to be governed principally by the crustal thinning gradient (taper) of the crystalline crust from unrifted crustal thickness down to a thickness less than 10 km. Surprisingly, the relationship appears to hold for very long time intervals (> 150 ma) after rifting and breakup. Offshore Norway, two end-member styles of crustal thinning are observed. Along the Mre margin, a basin-flank detachment complex thinned the crust dramatically from c. 40 to less than 10 km over a horizontal distance of < 100 km. Along the Trndelag Platform, however, thinning down to less than 10 km was distributed between 2-3 large-magnitude normal faults over a much broader region, which evolved into platform and terrace areas. The location, displacement magnitude and lateral arrangement of faults that developed in the margi?s `thinnin? phase governed the position of the proximal-distal margin boundary and thus the gross-scale thinning gradient, or taper, of the crystalline crust. In the onshore areas, the effects on topography, landscape and fault reactivation patterns are profound. The highest escarpment and the most asymmetric margin topography developed inboard of sharply tapering crystalline crust. Inboard of sharp tapers, strong landscape contrasts developed across lineaments that were reactivated after the main phase of Mesozoic rifting, but prior to the glaciations. Glacial erosion enhanced tectonically induced drainage patterns, resulting in an asymmetric landscape distribution with high-relief alpine topography preferentially developed on the footwall sides of reactivated faults. This, in turn, pre-destined these landscapes to increased rockslide susceptibility because in the deeply incised escarpment topography, glacial incision undercut structures that had been reactivated in the brittle mode. The above relationships indicate that extensional faulting exerts a long-term control on escarpment topography, landscape contrasts, geohazard susceptibility and sediment routing patterns along passive margins, through the establishment of the taper. On more than 40 published profiles through passive margins, we have measured the distance from the taper break (where the crust is thinned to 10 km or less) to the point of maximum topographic elevation on the adjacent escarpment (apparent taper length) and plotted it against the maximum escarpment elevation measured on each profile. Our analysis indicates that breakup age, glaciations and calculated mantle effects are all subordinate to the taper in controlling escarpment topography. Also, substituting the taper break with the COB does not yield a particularly tight relationship. These observations indicate that it is the thinning of continental crystalline crust down to <10 km and not the replacement of continental with oceanic crust that matters for the topography of the escarpment. Moreover, sharp reductions in the thickness of crystalline crust from <30 km down to less than 10 km do not appear to produce long-standing escarpments.

  5. Analysis of Multiple Manding Topographies during Functional Communication Training

    PubMed Central

    Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Winborn-Kemmerer, Lisa; Lee, John F.; Ibrahimovic, Muska

    2009-01-01

    We evaluated the effects of reinforcing multiple manding topographies during functional communication training (FCT) to decrease problem behavior for three preschool-age children. During Phase 1, a functional analysis identified conditions that maintained problem behavior for each child. During Phase 2, the childrens parents taught them to request positive reinforcers (attention or toys) via vocal manding, manual signing, or touching a picture/word card with or without a microswitch recording device. A non-concurrent multiple-baseline design across children was used to evaluate FCT outcomes. Results showed that problem behavior decreased for all three children. Results also indicated that the children initially used multiple manding topographies but displayed a preference for vocal manding over time. PMID:20354591

  6. Method and Apparatus for Creating a Topography at a Surface

    DOEpatents

    Adams, David P. (Albuquerque, NM); Sinclair, Michael B. (Albuquerque, NM); Mayer, Thomas M. (Albuquerque, NM); Vasile, Michael J. (Albuquerque, NM); Sweatt, William C. (Albuquerque, NM)

    2008-11-11

    Methods and apparatus whereby an optical interferometer is utilized to monitor and provide feedback control to an integrated energetic particle column, to create desired topographies, including the depth, shape and/or roughness of features, at a surface of a specimen. Energetic particle columns can direct energetic species including, ions, photons and/or neutral particles to a surface to create features having in-plane dimensions on the order of 1 micron, and a height or depth on the order of 1 nanometer. Energetic processes can include subtractive processes such as sputtering, ablation, focused ion beam milling and, additive processes, such as energetic beam induced chemical vapor deposition. The integration of interferometric methods with processing by energetic species offers the ability to create desired topographies at surfaces, including planar and curved shapes.

  7. Keratometry and corneal topography using multiple delay element OCT

    NASA Astrophysics Data System (ADS)

    Plesea, Lucian; Podoleanu, Adrian G.

    2008-02-01

    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.

  8. Magnetic Resonance Force Microscopy Combined with Surface Topography

    NASA Astrophysics Data System (ADS)

    Tsuji, Shigenori; Yoshinari, Yohsuke

    2007-03-01

    In this presentation, we will show magnetic resonance force microscopy imaging combined with surface topography. The individual and combined images taken in the same coordinate are presented for extraction of the position, shapes and spin density distribution of target phantoms. This imaging technique is useful applied when the surface needs to be investigated in relation to the influence of a material buried below the surface. In our method, the surface topography was observed by the AFM with tapping mode. The spin density distribution was measured by the MRFM with the cyclic saturation technique. The AFM and MRFM experiments were made one after another by using the same experimental set-up, and their images were merged together afterwards. The sample consists of two kind of materials, one is DPPH containing unpaird spins and the other is a glass bead. DPPH particles with the size of 58 micrometer and a 8.8 micrometer single bead were glued on a commercial cantilever.

  9. [Topography of a reference plane for ultrasonic thoracometry (author's transl)].

    PubMed

    Kugener, H; Hansmann, M

    1976-10-01

    A method of ultrasonic thoracometry is reported which uses the veins of the fetal liver as landmarks. The fact that the umbilical vein running from the anterior abdominal wall to the "sinus venae portae" is visible in B-scan display is the given presupposition. In a study about topography of the vein system of the fetal liver in 50 cases the description of a so called "sinus-plane" for sonar thoracometry is given. This reference plane is shown to be identical with the "lower apertura of the fetal thorax" recommended by Hansmann and co-workers since 1971. Thereby the nowadays well established method of thoracometry in obstetrical routine work gets a more accurate definition in regard to it's topography. This is not only of theoretical interest but will improve the conditions for more accuracy and reproducibility of the method. PMID:969791

  10. Role of membrane stresses in the support of planetary topography

    NASA Technical Reports Server (NTRS)

    Turcotte, D. L.; Willemann, R. J.; Haxby, W. F.; Norberry, J.

    1981-01-01

    The role of membrane stresses and bending stresses in supporting topographic loads on planetary elastic lithospheres is examined. A dimensionless parameter is introduced in order to determine the ability of a spherical shell to support loads through membrane stresses. It is determined that when this parameter is large, membrane stresses can fully support topographic loads with flexure, and when it is small the influence of the membrane stresses can be neglected. Equations governing the behavior of a spherical shell are solved for a topographic load expressed in terms of spherical harmonics, and spherical harmonic expansions of the measured gravity and topography for Mars and the moon are compared with the theory. It is concluded that membrane stresses play an important role in the support of topographic loads on the moon and Mars. The correlation of observed gravitational potential anomalies with the topography on Mars is explained by membrane stresses in the elastic lithosphere.

  11. Advances in corneal topography measurements with conical null-screens

    NASA Astrophysics Data System (ADS)

    Campos-Garca, Manuel; Cossio-Guerrero, Cesar; Huerta-Carranza, Oliver; Moreno-Oliva, Vctor I.

    2015-09-01

    In this work we report the design of a null-screen for corneal topography. 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 a novel radial points distribution drawn on it in such a way that its image, which is formed by reflection on the test surface, becomes an exact array of circular spots if the surface is perfect. Additionally, an algorithm to compute the sagittal and meridional radii of curvature for the corneal surface is presented. The sagittal radius is obtained from the surface normal, and the meridional radius is calculated from a function fitted to the derivative of the sagittal curvature by using the surfacenormals raw data. Experimental results for the testing a calibration spherical surface are shown. Also, we perform some corneal topography measurements.

  12. Three-dimensional measurement and characterization of grinding tool topography

    NASA Astrophysics Data System (ADS)

    Cui, Changcai; Blunt, Liam; Jiang, Xiangqian; Xu, Xipeng; Huang, Hui; Ye, Ruifang

    2013-01-01

    A comprehensive 3-dimensional measurement and characterization method for grinding tool topography was developed. A stylus instrument (SOMICRONIC, France) was used to measure the surface of a metal-bonded diamond grinding tool. The sampled data was input the software SurfStand developed by Centre for Precision Technology (CPT) for reconstruction and further characterization of the surface. Roughness parameters pertaining to the general surface and specific feature parameters relating to the grinding grits, such as height and angle peak curvature have been calculated. The methodology of measurement has been compared with that using an optical microscope. The comparison shows that the three-dimensional characterization has distinct advantages for grinding tool topography assessment. It is precise, convenient and comprehensive so it is suitable for precision measurement and analysis where an understanding of the grinding tool and its cutting ability are required.

  13. Topography, relief, climate and glaciers: a global prespective

    NASA Astrophysics Data System (ADS)

    Champagnac, Jean-Daniel; Valla, Pierre; Herman, fred

    2014-05-01

    The examination of the relationship between Earth's topography and present and past climate (i.e. long-term elevation of glaciers Equilibrium Line Altitude) reveals that the elevation of mountain ranges may be limited or controlled by glaciations. This is of prime importance, because glacial condition would lead to a limit the mountain development, hence the accumulation of gravitational energy and prevent the development of further glacial conditions as well as setting the erosion in (peri)glacial environments. This study examines the relationships between topography and the global Equilibrium Line Altitude of alpine glaciers around the world (long term snowline, i.e. the altitude where the ice mass balance is null). Two main observations can be drawn: 1) The distance between the (averaged and maximum) topography, and the ELA decreases pole ward the poles, and even become reversed (mean elevation above to ELA) at high latitude. Correlatively, the elevation of very large portion of land at mid-latitude cannot be related to glaciations, simply because it was never glaciated (large distance between topography and long-term mean ELA). The maximum distance between the ELA and the topography is greater close to the equator and decreases poleward. In absence of glacial and periglacial erosion, this trend cannot have its origin in glacial and periglacial processes. Moreover, the ELA elevation shows a significant (1000 - 1500m) depression in the intertropical zone. This depression of the ELA is not reflected at all in the topography. 2) The distribution of relief on Earth, if normalized by the mean elevation of mountain ranges (as a proxy for available space to create relief) shows a latitudinal band of greater relief between 40° and 60° (or between ELA of 500m to 2500m a.s.l.). This mid-latitude relatively greater relief challenges the straightforward relationship between glaciations, erosion and topography. Oppositely, it suggests that glacier may be more efficient agent in temperate area, with important amplitude between glacial and interglacial climate. This is consistent with the view of a very variable glacier erodibility that can erode and protect the landscape, as well as with studies documenting a bimodal location of the preferred glacial erosion, at relatively high elevation (around the long-term ELA), and at much lower elevation (close to the glacial maximum lower reaches), thanks to efficient water lubrication of the glacier bases that greatly enhance the sliding velocity. These findings show that the relation between the mountain topography and the long term snowline is not as straightforward as previously proposed. Beside the role of tectonic forcing highlighted by several authors, the importance of the glacial erosion appears to be crucial at mid latitude, but more complex at both high and low latitude. Moreover, the relief at mid latitude appears to be higher, hence suggesting a positive correlation between relief and topographic control of glacier on the landscape.

  14. Craters on Mars: Global Geometric Properties from Gridded MOLA Topography

    NASA Technical Reports Server (NTRS)

    Garvin, J. B.; Sakimoto, S. E. H.; Frawley, J. J.

    2003-01-01

    Impact craters serve as natural probes of the target properties of planetary crusts and the tremendous diversity of morphological expressions of such features on Mars attests to their importance for deciphering the history of crustal assembly, modification, and erosion. This paper summarizes the key findings associated with a five year long survey of the three-dimensional properties of approx. 6000 martian impact craters using finely gridded MOLA topography. Previous efforts have treated representative subpopulations, but this effort treats global properties from the largest survey of impact features from the perspective of their topography ever assimilated. With the Viking missions of the mid-1970 s, the most intensive and comprehensive robotic expeditions to any Deep Space location in the history of humanity were achieved, with scientifically stunning results associated with the morphology of impact craters. The relationships illustrated and suggest that martian impact features are remarkably sensitive to target properties and to the local depositional processes.

  15. Topography measurements and applications in ballistics and tool mark identifications

    NASA Astrophysics Data System (ADS)

    Vorburger, T. V.; Song, J.; Petraco, N.

    2016-03-01

    The application of surface topography measurement methods to the field of firearm and toolmark analysis is fairly new. The field has been boosted by the development of a number of competing optical methods, which has improved the speed and accuracy of surface topography acquisitions. We describe here some of these measurement methods as well as several analytical methods for assessing similarities and differences among pairs of surfaces. We also provide a few examples of research results to identify cartridge cases originating from the same firearm or tool marks produced by the same tool. Physical standards and issues of traceability are also discussed. Certain commercial equipment, instruments, or materials are identified in this paper to specify adequately the experimental procedure. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.

  16. Data on in vitro and in vivo cell orientation on substrates with different topographies

    PubMed Central

    English, Andrew; Azeem, Ayesha; Spanoudes, Kyriakos; Jones, Eleanor; Tripathi, Bhawana; Basu, Nandita; McNamara, Karrina; Tofail, Syed A.M.; Rooney, Niall; Riley, Graham; O׳Riordan, Alan; Cross, Graham; Hutmacher, Dietmar; Biggs, Manus; Pandit, Abhay; Zeugolis, Dimitrios I.

    2015-01-01

    This data article contains data related to the research article entitled “Substrate topography: A valuable in vitro tool, but a clinical red herring for in vivo tenogenesis” [1]. We report measurements on tenocyte viability, metabolic activity and proliferation on substrates with different topographies. We also report the effect of substrates with different topographies on host cells in a subcutaneous model. PMID:26977425

  17. Influence of topography on tropical African vegetation coverage

    NASA Astrophysics Data System (ADS)

    Jung, Gerlinde; Prange, Matthias; Schulz, Michael

    2015-07-01

    Hominid evolution in the late Miocene has long been hypothesized to be linked to the retreat of the tropical rainforest in Africa. One cause for the climatic and vegetation change often considered was uplift of Africa, but also uplift of the Himalaya and the Tibetan Plateau was suggested to have impacted rainfall distribution over Africa. Recent proxy data suggest that in East Africa open grassland habitats were available to the common ancestors of hominins and apes long before their divergence and do not find evidence for a closed rainforest in the late Miocene. We used the coupled global general circulation model CCSM3 including an interactively coupled dynamic vegetation module to investigate the impact of topography on African hydro-climate and vegetation. We performed sensitivity experiments altering elevations of the Himalaya and the Tibetan Plateau as well as of East and Southern Africa. The simulations confirm the dominant impact of African topography for climate and vegetation development of the African tropics. Only a weak influence of prescribed Asian uplift on African climate could be detected. The model simulations show that rainforest coverage of Central Africa is strongly determined by the presence of elevated African topography. In East Africa, despite wetter conditions with lowered African topography, the conditions were not favorable enough to maintain a closed rainforest. A discussion of the results with respect to other model studies indicates a minor importance of vegetation-atmosphere or ocean-atmosphere feedbacks and a large dependence of the simulated vegetation response on the land surface/vegetation model.

  18. Geoid, topography, and the Bouguer plate or shell

    NASA Astrophysics Data System (ADS)

    Vancek, P.; Novk, P.; Martinec, Z.

    2001-07-01

    Topography plays an important role in solving many geodetic and geophysical problems. In the evaluation of a topographical effect, a planar model, a spherical model or an even more sophisticated model can be used. In most applications, the planar model is considered appropriate: recall the evaluation of gravity reductions of the free-air, Poincar-Prey or Bouguer kind. For some applications, such as the evaluation of topographical effects in gravimetric geoid computations, it is preferable or even necessary to use at least the spherical model of topography. In modelling the topographical effect, the bulk of the effect comes from the Bouguer plate, in the case of the planar model, or from the Bouguer shell, in the case of the spherical model. The difference between the effects of the Bouguer plate and the Bouguer shell is studied, while the effect of the rest of topography, the terrain, is discussed elsewhere. It is argued that the classical Bouguer plate gravity reduction should be considered as a mathematical construction with unclear physical meaning. It is shown that if the reduction is understood to be reducing observed gravity onto the geoid through the Bouguer plate/shell then both models give practically identical answers, as associated with Poincar's and Prey's work. It is shown why only the spherical model should be used in the evaluation of topographical effects in the Stokes-Helmert solution of Stokes' boundary-value problem. The reason for this is that the Bouguer plate model does not allow for a physically acceptable condensation scheme for the topography.

  19. Electronic cigarettes: abuse liability, topography and subjective effects

    PubMed Central

    Evans, Sarah E; Hoffman, Allison C

    2014-01-01

    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

  20. In-process characterization of surface topography changes during nitration

    NASA Astrophysics Data System (ADS)

    Ciossek, Andreas; Lehmann, Peter; Patzelt, Stefan; Goch, Gert

    2000-09-01

    The nitration process influences the mechanical and chemical properties of steel and changes the near-surface characteristics. The nitrided surfaces are less sensitive to corrosive fluids and show a better stability against abrasion. Unfortunately, during treatment pores emerge at the surface. In general this is not desired, since the pores reduce the wear stability. The change of the near-surface characteristics also leads to a remodeling of the surface topography. For example, ground, smooth surfaces show an increased but isotropic roughness after nitration. During the recent years, various speckle techniques for an in-process characterization of surface topography have been improved significantly. One of these promising techniques is the method of trichromatic speckle autocorrelation. Its measuring principle is based on trichromatic light scattering and enables to determine an integral parameter of the surface roughness by the evaluation of the speckle elongation. Especially in the case of nitration, where the specimen is located in a stove filled with ammonia at a temperature of 580 degrees Celsius, this technique offers an in-processing monitoring of surface topography changes from outside the stove. In this paper, the in-process characterization of surface topography by speckle autocorrelation will be introduced. In this context an algorithm has been developed, which allows to estimate the position of the optical axis within the speckle pattern and therefore to determine the surface roughness as well as the local inclination of isotropic surfaces. An important goal of the current research is to realize a reliable process control based on the speckle autocorrelation, that is necessary to produce nitrided surfaces without pores in the compound layer and with good abrasive and corrosive resistance.

  1. Topography, albedo-temperature feedback, and climate sensitivity.

    PubMed

    Birchfield, G E; Wertman, J

    1983-01-21

    Numerical experiments with an energy balance model of the earth's climate suggest an enhancement of albedo-temperature feedback caused by the presence of a high middle-latitude plateau in the zonally averaged Northern Hemisphere topography. The increased climate sensitivity arises from the increased rate of change of snow cover produced by the advance or retreat of the winter snow line over the north slope of this topographic feature. PMID:17798274

  2. Correcting for surface topography in X-ray fluorescence imaging

    PubMed Central

    Geil, E. C.; Thorne, R. E.

    2014-01-01

    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

  3. Evaluating Marie Byrd Land stability using an improved basal topography

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

  4. ATM Coastal Topography-Florida 2001: Western Panhandle

    USGS Publications Warehouse

    Yates, Xan; Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Klipp, Emily S.; Wright, C. Wayne

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the western Florida panhandle coastline, acquired October 2-4 and 7-10, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM 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 presurvey 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.

  5. Towards Mapping the Ocean Surface Topography at 1 km Resolution

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng; Rodriquez, Ernesto

    2006-01-01

    We propose to apply the technique of synthetic aperture radar interferometry to the measurement of ocean surface topography at spatial resolution approaching 1 km. The measurement will have wide ranging applications in oceanography, hydrology, and marine geophysics. The oceanographic and related societal applications are briefly discussed in the paper. To meet the requirements for oceanographic applications, the instrument must be flown in an orbit with proper sampling of ocean tides.

  6. ATM Coastal Topography-Florida 2001: Eastern Panhandle

    USGS Publications Warehouse

    Yates, Xan; Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Klipp, Emily S.; Wright, C. Wayne

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the eastern Florida panhandle coastline, acquired October 2, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM 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 presurvey 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.

  7. ATM Coastal Topography-Texas, 2001: UTM Zone 14

    USGS Publications Warehouse

    Klipp, Emily S.; Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Yates, Xan; Wright, C. Wayne

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of lidar-derived first-surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Texas coastline within UTM zone 14, acquired October 12-13, 2001. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative scanning lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM 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 presurvey 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 used routinely to create maps that represent submerged or first-surface topography.

  8. ATM Coastal Topography-Texas, 2001: UTM Zone 15

    USGS Publications Warehouse

    Klipp, Emily S.; Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Bonisteel, Jamie M.; Yates, Xan; Wright, C. Wayne

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of lidar-derived first-surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Texas coastline within UTM zone 15, from Matagorda Peninsula to Galveston Island, acquired October 12-13, 2001. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative scanning lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM 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 presurvey 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 used routinely to create maps that represent submerged or first-surface topography.

  9. Reproducibility study of Placido-based corneal topography systems

    NASA Astrophysics Data System (ADS)

    Krueger, Ronald R.; Frankel, Roddy; Assil, Kerry K.; Schanzlin, David J.; Guirgis, Medhat F.

    1995-05-01

    We have developed a computer software program that analyzes the reproducibility of corneal topography systems. Using a Macintosh computer with Microsoft QuickBasic programming we created a program that records and analyzes the corneal power of 72,000 points per topography map (200 points over each one degree meridian) by linear interpolation of the Placido-based ring data. Reproducibility studies on 7 normal and 7 abnormal (pathological and postsurgical) corneas were performed with 2 Placido ring based topography systems with EyeSys Corneal Analysis System and the Humphrey MasterView system. Five exams were performed by two technicians each. The mean, range and standard deviation of corneal power was calculated for all points on a map, and represented pictorially for each patient. Statistical analysis of standard deviation at each point was used in assessing the reproducibility between systems and between technicians. The topographic maps of mean power range and standard deviation are presented for selected patients. The overall mean standard deviation of power and the means within concentric annular zones and quadrants are presented for each system and technician for both normal and abnormal cornea. Intraobserver variability of each system were not significantly different for both normal and abnormal corneas. There was no significant difference between technicians, nor were there regional differences in variability.standard deviation of power is presented for each system and technician comparing intersystem and intraobserver variability for both normal and abnormal corneas. A precise method of analyzing multiple variation of reproducibility in corneal topography is now available through a new proprietary software system.

  10. Moho depth and residual topography of the Antarctic continent

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

    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.

  11. Solitary wave dynamics in shallow water over periodic topography.

    PubMed

    Nakoulima, Ousseynou; Zahibo, Narcisse; Pelinovsky, Efim; Talipova, Tatiana; Kurkin, Andrey

    2005-09-01

    The problem of long-wave scattering by piecewise-constant periodic topography is studied both for a linear solitary-like wave pulse, and for a weakly nonlinear solitary wave [Korteweg-de Vries (KdV) soliton]. If the characteristic length of the topographic irregularities is larger than the pulse length, the solution of the scattering problem is obtained analytically for a leading wave in the framework of linear shallow-water theory. The wave decrement in the case of the small height of the topographic irregularities is proportional to delta2, where delta is the relative height of the topographic obstacles. An analytical approximate solution is also obtained for the weakly nonlinear problem when the length of the irregularities is larger than the characteristic nonlinear length scale. In this case, the Korteweg-de Vries equation is solved for each piece of constant depth by using the inverse scattering technique; the solutions are matched at each step by using linear shallow-water theory. The weakly nonlinear solitary wave decays more significantly than the linear solitary pulse. Solitary wave dynamics above a random seabed is also discussed, and the results obtained for random topography (including experimental data) are in reasonable agreement with the calculations for piecewise topography. PMID:16253002

  12. Cellular Scale Anisotropic Topography Guides Schwann Cell Motility

    PubMed Central

    Mitchel, Jennifer A.; Hoffman-Kim, Diane

    2011-01-01

    Directed migration of Schwann cells (SC) is critical for development and repair of the peripheral nervous system. Understanding aspects of motility specific to SC, along with SC response to engineered biomaterials, may inform strategies to enhance nerve regeneration. Rat SC were cultured on laminin-coated microgrooved poly(dimethyl siloxane) platforms that were flat or presented repeating cellular scale anisotropic topographical cues, 30 or 60 m in width, and observed with timelapse microscopy. SC motion was directed parallel to the long axis of the topography on both the groove floor and the plateau, with accompanying differences in velocity and directional persistence in comparison to SC motion on flat substrates. In addition, feature dimension affected SC morphology, alignment, and directional persistence. Plateaus and groove floors presented distinct cues which promoted differential motility and variable interaction with the topographical features. SC on the plateau surfaces tended to have persistent interactions with the edge topography, while SC on the groove floors tended to have infrequent contact with the corners and walls. Our observations suggest the capacity of SC to be guided without continuous contact with a topographical cue. SC exhibited a range of distinct motile morphologies, characterized by their symmetry and number of extensions. Across all conditions, SC with a single extension traveled significantly faster than cells with more or no extensions. We conclude that SC motility is complex, where persistent motion requires cellular asymmetry, and that anisotropic topography with cellular scale features can direct SC motility. PMID:21949703

  13. Synthetic aperture inversion for arbitrary flight paths and nonflat topography.

    PubMed

    Nolan, Clifford J; Cheney, Margaret

    2003-01-01

    This paper considers synthetic aperture radar (SAR) and other synthetic aperture imaging systems in which a backscattered wave is measured from positions along an arbitrary (known) flight path. The received backscattered signals are used to produce an image of the terrain. We assume a single-scattering model for the radar data, and we assume that the ground topography is known but not necessarily flat. We focus on cases in which the antenna footprint is so large that the standard narrow-beam algorithms are not useful. We show that certain artifacts can be avoided if the antenna and antenna footprint avoid particular relationships with the ground topography. We give an explicit backprojection imaging algorithm that corrects for the ground topography, flight path, antenna beam pattern, source waveform, and other geometrical factors. For the case of a non-directional antenna, the image produced by the above algorithm contains artifacts. For this case, we analyze the strength of the artifacts relative to the strength of the true image. The analysis shows that the artifacts can be somewhat suppressed by increasing the frequency, integration time, and the curvature of the flight path. PMID:18237975

  14. Permian karst topography in the Wichita uplift, southwestern Oklahoma

    SciTech Connect

    Donovan, R.N. Busbey, A.B. . Geology Dept.)

    1993-02-01

    The Wichita uplift in southwestern Oklahoma is one part of a record of Pennsylvania and early Permian deformation that affected the Southern Oklahoma aulacogen. As a result of a partial inversion, the Lower Paleozoic section of this aulacogen was sequentially stripped off an uplift between the Wichita uplift and the Anadarko basin, resulting in the exposure of ultrabasic rocks deep in the Cambrian igneous fill of the aulacogen. Following the late Paleozoic tectonism, the topography of the uplift was entombed beneath Permian sediments and remained essentially undisturbed until exhumation during the present erosional cycle. Modern erosion is gradually exposing this topography, permitting morphometric analysis of the Permian hill forms. Because of the variation of lithology in the uplift, it is possible to isolate the effects of weathering processes such as intense hydrolysis of the igneous rocks (producing, among other features, or topography) and limestone dissolution, in the form of a surface and subsurface karst imprint. The latter process resulted in a network of small caves that are essentially fissures eroded along tectonic fractures. These small caves can be found in all the exposed areas of limestone. They are particularly noteworthy for three reasons: in at least five examples they contain a complex fauna of Permian vertebrates (mostly fragmentary), speleothems in some examples contain hydrocarbon inclusions, derived from the underlying Anadarko basin, some of the caves yield evidence of post burial evolution in the form of clay infiltration from the surface and brine flushing from the underlying Anadarko basin.

  15. Fractal and Lacunarity Analyses: Quantitative Characterization of Hierarchical Surface Topographies.

    PubMed

    Ling, Edwin J Y; Servio, Phillip; Kietzig, Anne-Marie

    2016-02-01

    Biomimetic hierarchical surface structures that exhibit features having multiple length scales have been used in many technological and engineering applications. Their surface topographies are most commonly analyzed using scanning electron microscopy (SEM), which only allows for qualitative visual assessments. Here we introduce fractal and lacunarity analyses as a method of characterizing the SEM images of hierarchical surface structures in a quantitative manner. Taking femtosecond laser-irradiated metals as an example, our results illustrate that, while the fractal dimension is a poor descriptor of surface complexity, lacunarity analysis can successfully quantify the spatial texture of an SEM image; this, in turn, provides a convenient means of reporting changes in surface topography with respect to changes in processing parameters. Furthermore, lacunarity plots are shown to be sensitive to the different length scales present within a hierarchical structure due to the reversal of lacunarity trends at specific magnifications where new features become resolvable. Finally, we have established a consistent method of detecting pattern sizes in an image from the oscillation of lacunarity plots. Therefore, we promote the adoption of lacunarity analysis as a powerful tool for quantitative characterization of, but not limited to, multi-scale hierarchical surface topographies. PMID:26758776

  16. Crustal thickness and support of topography on Venus

    NASA Astrophysics Data System (ADS)

    James, Peter B.; Zuber, Maria T.; Phillips, Roger J.

    2013-04-01

    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 these mechanisms could play a role in compensating topography on Venus, and we distinguish between these mechanisms in part by calculating geoid-to-topography ratios and apparent depths of compensation. By simultaneously inverting for mass anomalies at two depths, we solve for the spatial distribution of crustal thickness and a similar map of mass anomalies in the mantle, thus separating the effects of shallow and deep compensation mechanisms on the geoid. The roughly circular regions of mantle mass deficit coincide with the locations of what are commonly interpreted to be buoyant mantle plumes. Additionally, there is a significant geographic correlation between patches of thickened crust and mass deficits in the mantle, especially for spherical harmonic degree l < 40. These mass deficits may be interpreted either as lateral thermal variations or as Mg-rich melt residuum. The magnitudes of mass deficits under the crustal highlands are roughly consistent with a paradigm in which highland crust is produced by melting of upwelling plumes. The mean thickness of the crust is constrained to a range of 8-25 km, somewhat lower than previous estimates. The best two-layered inversion of gravity incorporates a dynamic mantle load at a depth of 250 km.

  17. The generation of internal tides at abrupt topography

    NASA Astrophysics Data System (ADS)

    St. Laurent, Louis; Stringer, Steven; Garrett, Chris; Perrault-Joncas, Dominique

    2003-08-01

    Internal tide generation is examined for a knife-edge ridge and an abrupt step. The energy flux from a knife-edge ridge with a height much less than the water depth is shown to be twice that from a Witch of Agnesi ridge with the same height but a small slope. In contrast, the energy flux from an abrupt step with an infinitesimal depth change compared to the water depth is the same as from a small slope with the same depth change. For larger topographic heights in both cases, the energy flux from the abrupt topography can significantly exceed that from gentle topography. The energy flux generated at a top-hat ridge and top-hat trench is also calculated. A top-hat ridge generates more energy flux than a knife edge of equivalent height, though the increase is large only for ridges whose height is small compared to the total depth. Additionally, the energy flux produced by a top-hat ridge is found to be rather insensitive to the ridge width. In contrast, the energy flux generated at a top-hat trench is strongly dependent on width. A knife-edge ridge of moderate height has much of its energy flux in mode 1. For a height to depth ratio comparable to that of the Hawaiian Ridge this fraction is 75%, consistent with observations. We also show that energy flux estimates based on representing general topography as a number of independent steps are flawed.

  18. Anomalous topography on the continental shelf around Hudson Canyon

    USGS Publications Warehouse

    Knebel, H. J.

    1979-01-01

    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.

  19. Surface topography estimated by inversion of satellite gravity gradiometry observations

    NASA Astrophysics Data System (ADS)

    Ramillien, Guillaume

    2015-04-01

    An integration of mass elements is presented for evaluating the six components of the 2-order gravity tensor (i.e., second derivatives of the Newtonian mass integral for the gravitational potential) created by an uneven sphere topography consisting of juxtaposed vertical prisms. The method is based on Legendre polynomial series with the originality of taking elastic compensation of the topography by the Earth's surface into account. The speed of computation of the polynomial series increases logically with the observing altitude from the source of anomaly. Such a forward modelling can be easily used for reduction of observed gravity gradient anomalies by the effects of any spherical interface of density. Moreover, an iterative least-square inversion of the observed gravity tensor values ??? is proposed to estimate a regional set of topographic heights. Several tests of recovery have been made by considering simulated gradiometry anomaly data, and for varying satellite altitudes and a priori levels of accuracy. In the case of GOCE-type gradiometry anomalies measured at an altitude of ~300 km, the search converges down to a stable and smooth topography after 20-30 iterations while the final r.m.s. error is ~100 m. The possibility of cumulating satellite information from different orbit geometries is also examined for improving the prediction.

  20. Puffing Topography and Nicotine Intake of Electronic Cigarette Users

    PubMed Central

    Behar, Rachel Z.; Hua, My; Talbot, Prue

    2015-01-01

    Background Prior electronic cigarette (EC) topography data are based on two video analyses with limited parameters. Alternate methods for measuring topography are needed to understand EC use and nicotine intake. Objectives This study evaluated EC topography with a CReSS Pocket device and quantified nicotine intake. Methods Validation tests on pressure drop, flow rate, and volume confirmed reliable performance of the CReSS Pocket device. Twenty participants used Blu Cigs and V2 Cigs for 10 minute intervals with a 10–15 minute break between brands. Brand order was reversed and repeated within 7 days Data were analyzed to determine puff duration, puff count, volume, flow rate, peak flow, and inter-puff interval. Nicotine intake was estimated from cartomizer fluid consumption and topography data. Results Nine patterns of EC use were identified. The average puff count and inter-puff interval were 32 puffs and 17.9 seconds. All participants, except one, took more than 20 puffs/10 minutes. The averages for puff duration (2.65 seconds/puff), volume/puff (51ml/puff), total puff volume (1,579 ml), EC fluid consumption (79.6 mg), flow rate (20 ml/s), and peak flow rate (27 ml/s) were determined for 10-minute sessions. All parameters except total puff count were significantly different for Blu versus V2 EC. Total volume for Blu versus V2 was four-times higher than for conventional cigarettes. Average nicotine intake for Blu and V2 across both sessions was 1.2 ± 0.5 mg and 1.4 ± 0.7 mg, respectively, which is similar to conventional smokers. Conclusions EC puffing topography was variable among participants in the study, but often similar within an individual between brands or days. Puff duration, inter-puff interval, and puff volume varied from conventional cigarette standards. Data on total puff volume and nicotine intake are consistent with compensatory usage of EC. These data can contribute to the development of a standard protocol for laboratory testing of EC products. PMID:25664463

  1. The Relationship between Dynamic Topography and Sequence Stratigraphy

    NASA Astrophysics Data System (ADS)

    White, N. J.

    2014-12-01

    An evolving pattern of convective circulation within the mantle generates and maintains dynamic topography which is some fraction of observed topography. Spatial variations of dynamic topography are easy to measure within the oceanic realm and it is possible to exploit inventories of seismic reflection and wide-angle data to determine the dynamic topography of the oldest oceanic lithosphere that abuts passive continental margins. Results show that oceanic lithosphere has dynamic topographic anomalies of +/- 1 km with wavelengths of 500-1000 km. These substantial anomalies intersect coastal shelves and so it is expected that the development of these anomalies has affected sequence stratigraphic architecture in important ways. A series of examples will be used to illustrate how sequence stratigraphy can be profoundly influenced by changing patterns of dynamic topography. First, along the West African margin a set of dynamic topographic domes intersect the shelf edge. Onshore, the Neogene growth of these domes is recorded by emergent terraces and by drainage patterns. Offshore, an Oligo-Miocene switch from aggradation to progradation together with a series of younger disconformities have modified stratigraphic architecture along the shelf. Secondly, along the Northwest Shelf of Australia there is evidence for 700 m of dynamic drawdown of the oldest oceanic floor. Regional mapping and backstripping of clinoformal geometries within a Miocene carbonate reef complex shows that there is a dramatic switch from progradation to aggradation which cannot be attributed to glacio-eustatic variations. Instead, this switch appears to reflect growth of dynamic drawdown within the mantle. Finally, the Icelandic plume has controlled vertical motions along fringing North Atlantic margins over the last 60 Ma. Thanks to the intersecting mid-oceanic ridge, there is independent evidence that the temperature structure of this plume has fluctuated through time. These fluctuations are recorded within the detailed sequence stratigraphy of the margins where a series of ephemeral terrestrial landscapes have been mapped. Stratigraphic architecture appears to be an important repository of details about transient convective circulation which are otherwise difficult to obtain.

  2. Reconstructing Pliocene coastlines, topography and bathymetry: A geodynamic perspective

    NASA Astrophysics Data System (ADS)

    Chandan, D.; Peltier, W. R.

    2014-12-01

    The middle Pliocene period (~3.3-3.0 Mya) was characterized by warm temperatures (2-3℃ higher) and high carbon-dioxide (~400 ppmv) concentrations which has led to its recognition as a possible analogue for the future climate. Under the auspices of the Pliocene Modeling and Intercomparison Project (PlioMIP), general circulation models (GCM's) are being employed to simulate mid-Pliocene climate to better understand the biases in these models, which are presently used to make future climate predictions. Necessary boundary conditions for these simulations — land mask, topography, surface albedo and vegetation cover are being provided by the Pliocene Research, Interpretation and Synoptic Mapping (PRISM) project. Bathymetry, which is not part of the PRISM supplied dataset has been adjusted by raising the sea-level by an assumed constant eustatic amount. At present the PRISM land mask, topography and bathymetry reconstructions do not incorporate the gravitationally self consistent changes that would be required to account for the mass loss from the Greenland and Antarctic ice-sheets that produced the assumed rise in eustatic sea level. The effects of dynamic topography induced corrections, due to the action of the mantle convection process, have also been neglected.The influence of these corrections on the predictions of Pliocene climate using modern GCM's remains unexplored. The continuing failure of these models to simulate proxy inferred levels of warming in high-latitude [Dowsett et al., 2013, Sci. Rep.] regions where the magnitude of the required corrections are expected to be largest make it especially important that their impact be assessed. Here, we present the results from a preliminary of the required modifications to the boundary condition data sets.We compute the gravitationally self consistent corrections using the viscoelastic theory of global, glacial isostatic adjustment and relative sea level history for a spherically symmetric Earth model. Dynamic topography related changes are computed using a 3D convection model initialized using seismic tomography. Together, this creates an updated picture of the mid-Pliocene shoreline, topography and bathymetry that can be employed as boundary conditions for future Pliocene climate modeling.

  3. Global snowline and mountain topography: a contrasted view

    NASA Astrophysics Data System (ADS)

    Champagnac, Jean-Daniel; Herman, Frédéric; Valla, Pierre

    2013-04-01

    The examination of the relationship between Earth's topography and present and past climate (i.e., long-term elevation of glaciers Equilibrium Line Altitude) reveals that the elevation of mountain ranges may be limited or controlled by glaciations (e.g. Porter, 1989). This is of prime importance, because glacial condition would lead to a limit the mountain development, hence the accumulation of gravitational energy and prevent the development of further glacial conditions as well as setting the erosion in (peri)glacial environments. In this study, we examine the relationships between topography and the global Equilibrium Line Altitude of alpine glaciers around the world (~ long term snowline, i.e. the altitude where the ice mass balance is null). This analysis reinforce a global study previously published (Champagnac et al., 2012), and provide a much finer view of the climate-topography-tectonics relationships. Specifically, two main observations can be drawn: 1) The distance between the (averaged and maximum) topography, and the ELA decreases pole ward the poles, and even become reversed (mean elevation above to ELA) at high latitude. Correlatively, the elevation of very large portion of land at mid-latitude cannot be related to glaciations, simply because it was never glaciated (large distance between topography and long-term mean ELA). The maximum distance between the ELA and the topography is greater close to the equator and decreases poleward. In absence of glacial and periglacial erosion, this trend cannot have its origin in glacial and periglacial processes. Moreover, the ELA elevation shows a significant (1000~1500m) depression in the intertropical zone. This depression of the ELA is not reflected at all in the topography 2) The distribution of relief on Earth, if normalized by the mean elevation of mountain ranges (as a proxy for available space to create relief, see Champagnac et al., 2012 for details) shows a latitudinal band of greater relief between ~40 and ~60° (or between ELA of ~500m to ~2500m a.s.l.). This mid-latitude relatively greater relief challenges the straightforward relationship between glaciations, erosion and topography. Oppositely, it suggests that glacier may be more efficient agent in temperate area, with an important amplitude between glacial and interglacial climate. This is consistent with the view of a very variable glacier erodibility that can erode and protect the landscape, as well as with studies documenting a bimodal location of the preferred glacial erosion, at relatively high elevation (around the long-term ELA), and at much lower elevation (close to the glacial maximum lower reaches), thanks to efficient water lubrication of the glacier bases that greatly enhance the sliding velocity (Herman et al., 2011). These findings show that the relation between the mountain topography and the long term snowline is not as straightforward as previously proposed (e.g. Egholm et al., 2009) . Beside the role of tectonic forcing highlighted by several authors (e.g. Pedersen et al., 2010;Spotila and Berger, 2010),, the importance of the glacial erosion appears to be crucial at mid latitude, but more complex at both high and low latitude. Moreover, the relief at mid latitude appears to be higher, hence suggesting a positive correlation between relief and topographic control of glacier on the landscape Champagnac, J.-D., Molnar, P., Sue, C., and Herman, F.: Tectonics, Climate, and Mountain Topography, Journal of Geophysical Research B: Solid Earth, 117, doi:10.1029/2011JB008348, 2012. Egholm, D. L., Nielsen, S. B., Pedersen, V. K., and Lesemann, J. E.: Glacial effects limiting mountain height, Nature, 460, 884-888, 2009. Herman, F., Beaud, F., Champagnac, J.-D., Lemieux, J.-M., and Sternai, P.: Glacial hydrology and erosion patterns: A mechanism for carving glacial valleys, Earth and Planetary Science Letters, 310, 498-508, 2011. Pedersen, V. K., Egholm, D. L., and Nielsen, S. B.: Alpine glacial topography and the rate of rock column uplift: a global perspective, Geomorphology, 122, 129-139, 10.1016/j.geomorph.2010.06.005, 2010. Porter, S. C.: Some geological implications of average Quaternary glacial conditions., Quaternary Research, 32, 245-261, 1989. Spotila, J. A., and Berger, A. L.: Exhumation at orogenic indentor corners under long-term glacial conditions: Example of the St. Elias orogen, Southern Alaska, Tectonophysics, 490, 241-256, doi:10.1016/j.tecto.2010.05.015, 2010.

  4. Geophysics of Titan from gravity, topography and spin state

    NASA Astrophysics Data System (ADS)

    Nimmo, F.; Bills, B. G.

    2011-12-01

    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 acquired topography [3], gravity [4] and spin pole constraints [5] now permit these kinds of geophysical analyses at Titan. Titan's degree-two gravity coefficients, but not those of its topography, are in the 10/3 ratio expected for a hydrostatic body. One explanation for this discrepancy is the existence of a floating isostatic ice shell whose thickness varies spatially due to tidal dissipation [6]. Shell thickness variations can result in slow non-synchronous rotation [7]. Furthermore, such variations will affect the gravity, an effect that should be taken into account when using gravity to calculate Titan's moment of inertia [4]. The relationship between the degree-three gravity and topography can be used to place constraints on the thickness and rigidity of the ice shell. Based on the inferred heat fluxes of [6], Titan's ice shell is unlikely to be less than 90% compensated at degree three. The measured degree-three gravity [4] and topography [3] coefficients show a strong correlation (r=0.84). For a completely compensated ice shell, the implied shell thickness is about 350 km, while if the shell is 90% compensated the thickness is 250 km. These shell thickness estimates significantly exceed those based on theoretical models [8,9] and surface topography [6]. One possible explanation for this discrepancy is that there are other sources of degree-three gravity (e.g. bumps on the presumed silicate core) that do not contribute significantly to the surface topography. Further gravity observations will help to resolve this issue. If a satellite's spin and orbit poles remain coplanar as the latter precesses around the invariable pole, the satellite is said to occupy a damped Cassini state and the obliquity (angle between spin and orbit pole) is diagnostic of its moment of inertia [10]. Titan's spin pole is very nearly coplanar with the orbit and invariable poles, suggesting occupation of a Cassini state. Its obliquity of 0.32 degrees [5] corresponds to a normalized moment of inertia of 0.45, much larger than the value of 0.34 derived from gravity [4]. This discrepancy is probably due mostly to decoupling of the ice shell from the interior by an ocean, though excitation of the obliquity by the atmosphere [11] or ocean may also play a role. [1] Wieczorek, M.A., Treatise Geophys. 10, 165-206, 2007. [2] Williams, J.G. et al., JGR 106, 27933-27968, 2001. [3] Zebker, H.A. et al., Science 324, 921-923, 2009. [4] Iess, L. et al., Science 327, 1367-1369, 2010. [5] Stiles, B.W. et al., Astron. J. 135, 1669-1680, 2008. [6] Nimmo, F., B.G. Bills, Icarus 208, 896-904, 2010. [7] Ojakangas, G.W., D.J. Stevenson, Icarus 81, 220-41, 1989. [8] Tobie, G. et al., Nature 440, 61-64, 2006. [9] Sohl, F. et al., JGR 108, 5130, 2003. [10] Bills, B.G., F. Nimmo, Icarus 214, 351-355, 2011. [11] Tokano, T. et al., JGR 116, E05002, 2011.

  5. Open questions in surface topography measurement: a roadmap

    NASA Astrophysics Data System (ADS)

    Leach, Richard; Evans, Christopher; He, Liangyu; Davies, Angela; Duparré, Angela; Henning, Andrew; Jones, Christopher W.; O'Connor, Daniel

    2015-03-01

    Control of surface topography has always been of vital importance for manufacturing and many other engineering and scientific disciplines. However, despite over one hundred years of quantitative surface topography measurement, there are still many open questions. At the top of the list of questions is ‘Are we getting the right answer?’ This begs the obvious question ‘How would we know?’ There are many other questions relating to applications, the appropriateness of a technique for a given scenario, or the relationship between a particular analysis and the function of the surface. In this first ‘open questions’ article we have gathered together some experts in surface topography measurement and asked them to address timely, unresolved questions about the subject. We hope that their responses will go some way to answer these questions, address areas where further research is required, and look at the future of the subject. The first section ‘Spatial content characterization for precision surfaces’ addresses the need to characterise the spatial content of precision surfaces. Whilst we have been manufacturing optics for centuries, there still isn’t a consensus on how to specify the surface for manufacture. The most common three methods for spatial characterisation are reviewed and compared, and the need for further work on quantifying measurement uncertainties is highlighted. The article is focussed on optical surfaces, but the ideas are more pervasive. Different communities refer to ‘figure, mid-spatial frequencies, and finish’ and ‘form, waviness, and roughness’, but the mathematics are identical. The second section ‘Light scattering methods’ is focussed on light scattering techniques; an important topic with in-line metrology becoming essential in many manufacturing scenarios. The potential of scattering methods has long been recognized; in the ‘smooth surface limit’ functionally significant relationships can be derived from first principles for statistically stationary, random surfaces. For rougher surfaces, correlations can be found experimentally for specific manufacturing processes. Improvements in computational methods encourage us to revisit light scattering as a powerful and versatile tool to investigate surface and thin film topographies, potentially providing information on both topography and defects over large areas at high speed. Future scattering techniques will be applied for complex film systems and for sub-surface damage measurement, but more research is required to quantify and standardise such measurements. A fundamental limitation of all topography measurement systems is their finite spatial bandwidth, which limits the slopes that they can detect. The third section ‘Optical measurements of surfaces containing high slope angles’ discusses this limitation and potential methods to overcome it. In some cases, a rough surface can allow measurement of slopes outside the classical optics limit, but more research is needed to fully understand this process. The last section ‘What are the challenges for high dynamic range surface measurement?’ presents the challenge facing metrologists by the use of surfaces that need measurement systems with very high spatial and temporal bandwidths, for example, those found in roll-to-roll manufacturing. High resolution, large areas and fast measurement times are needed, and these needs are unlikely to be fulfilled by developing a single all-purpose instrument. A toolbox of techniques needs to be developed which can be applied for any specific manufacturing scenario. The functional significance of surface topography has been known for centuries. Mirrors are smooth. Sliding behaviour depends on roughness. We have been measuring surfaces for centuries, but we still face many challenges. New manufacturing paradigms suggest that we need to make rapid measurements online that relate to the functional performance of the surface. This first ‘open questions’ collection addresses a subset of the challenges facing the surface metrology community. There are many more challenges which we would like to address in future ‘open questions’ articles. We welcome your feedback and your suggestions.

  6. Crater topography on Titan: Implications for landscape evolution

    NASA Astrophysics Data System (ADS)

    Neish, C.; Kirk, R.; Lorenz, R.; Bray, V.; Schenk, P.; Stiles, B.; Turtle, E.; Cassini Radar Team

    2012-04-01

    Unique among the icy satellites, Titans surface shows evidence for extensive modification by fluvial and aeolian erosion, which act to change the topography of its surface over time. Quantifying the extent of this landscape evolution is difficult, since the original, non-eroded surface topography is generally unknown. However, fresh craters on icy satellites have a well-known shape and morphology, which has been determined from extensive studies on the airless worlds of the outer solar system (Schenk et al., 2004). By comparing the topography of craters on Titan to similarly sized, pristine analogues on airless bodies, we can obtain one of the few direct measures of the amount of erosion that has occurred on Titan. Cassini RADAR has imaged >30% of the surface of Titan, and more than 60 potential craters have been identified in this data set (Wood et al., 2010; Neish and Lorenz, 2012). Topographic information for these craters can be obtained from a technique known as SARTopo, which estimates surface heights by comparing the calibration of overlapping synthetic aperture radar (SAR) beams (Stiles et al., 2009). We present topography data for several craters on Titan, and compare the data to similarly sized craters on Ganymede, for which topography has been extracted from stereo-derived digital elevation models (Bray et al., 2012). We find that the depths of craters on Titan are generally within the range of depths observed on Ganymede, but several hundreds of meters shallower than the average (Fig. 1). A statistical comparison between the two data sets suggests that it is extremely unlikely that Titans craters were selected from the depth distribution of fresh craters on Ganymede, and that is it much more probable that the relative depths of Titan are uniformly distributed between fresh and completely infilled. This is consistent with an infilling process that varies linearly with time, such as aeolian infilling. Figure 1: Depth of craters on Titan (gray diamonds) compared to similarly sized, fresh craters on Ganymede (central peaks, +; central pits, *) and a handful of relaxed craters (black squares) from Bray et al. (2012). References: Bray, V., et al.: "Ganymede crater dimensions - implications for central peak and central pit formation and development". Icarus, Vol. 217, pp. 115-129, 2012. Neish, C.D., Lorenz, R.D.: "Titans global crater population: A new assessment". Planetary and Space Science, Vol. 60, pp. 26-33, 2012. Schenk, P.M., et al.: "Ages and interiors: the cratering record of the Galilean satellites". In: Bagenal, F., McKinnon, W.B. (Eds.), Jupiter: The Planet, Satellites, and Magnetosphere, Cambridge University Press, Cambridge, UK, pp. 427-456, 2004. Stiles, B.W., et al.: "Determining Titan surface topography from Cassini SAR data". Icarus, Vol. 202, pp. 584-598, 2009. Wood, C.A., et al.: "Impact craters on Titan". Icarus, Vol. 206, pp. 334-344, 2010.

  7. Reconstructed Paleo-topography of the Columbia Hills, Mars

    NASA Astrophysics Data System (ADS)

    Cole, S. B.; Watters, W. A.; Aron, F.; Squyres, S. W.

    2013-12-01

    From June 2004 through March 2010, the Mars Exploration Rover Spirit conducted a detailed campaign examining the Columbia Hills of Gusev Crater. In addition to mineralogical and chemical investigations, Spirit's stereo panoramic (Pancam) and navigation (Navcam) cameras obtained over 7,000 images of geologic targets along the West Spur of the Columbia Hills and Husband Hill, the highest peak. We have analyzed the entirety of this dataset, which includes stereo coverage of several outcrop exposures with apparent bedding. We have measured the bedding plane orientations of hundreds of fine-scale (~1-100cm) features on all of the potentially in-place outcrops using Digital Terrain Models (DTMs) derived from the rover's Pancam stereo image data, and mapped these orientations on a regional HiRISE image and DTM. Assuming that the bedding material was deposited conformably on the topography at the time of emplacement, we reconstruct the paleo-topography of the Columbia Hills. Our reconstructed paleo-topography is similar to the modern shape of Husband Hill, but with steeper slopes, consistent with a substantial amount of erosion since deposition. The Columbia Hills are an irregular, nearly-triangular edifice of uncertain origin, situated near the center of the 160km-diameter crater and hypothesized to be either the remnant of a central peak structure, or overlapping crater rims. They span ~6.6 km in the northerly direction by ~3.6 km in the easterly direction, and rise 90m above the basaltic plains that fill the floor of Gusev Crater and embay the Hills. The topography is as irregular as the perimeter, and is cut by numerous valleys of varying lengths, widths, and directional trends. Along the traverse, Spirit examined several rock classes as defined by elemental abundances from the Alpha Particle X-ray Spectrometer (APXS) and identified remotely by the Miniature Thermal Emission Spectrometer (Mini-TES). Unlike the Gusev Plains, the rocks of the Columbia Hills show extensive evidence of aqueous alteration. Many of the outcrops are believed to have formed from volcanic and/or impact-related airfall material, which should drape the topography that existed at the time of emplacement. Outcrop bedding plane orientations are not consistent with the depositional material draping the current Columbia Hills edifice: dip magnitudes are steeper than the modern topographic slopes, and dip directions are not correlated with the modern topographic slope directions. There are, however, regional trends consistent with the outcrops draping an ancient underlying topography. Planes representing compositionally similar outcrops on the modern Husband Hill summit and to the northwest converge over the modern Tennessee Valley. If the paleo-structure culminated in the peak suggested by the bedding plane orientations, up to 100m of material may have been removed from the Columbia Hills.

  8. Constraints on Titan's Topography Through Fractal Analysis of Shorelines

    NASA Astrophysics Data System (ADS)

    Sharma, P.; Byrne, S.

    2008-12-01

    The recent discovery of hydrocarbon lakes at Titan's North Pole by the Radio Detection and Ranging (RADAR) instrument onboard the Cassini spacecraft is one of the most exciting discoveries of the Cassini-Huygens mission. Previous analyses of terrestrial coastlines have revealed them to be closely approximated by self-similar fractals. Coastline length increases as the measuring scale decreases because smaller measuring scales are sensitive to smaller features of the coastline. The measured perimeter can be related to the measuring scale by a power law whose exponent is 1-D, where D is the fractal dimension. The value of D provides a means to quantify the complexity (ruggedness) of a coastline with higher values indicating higher complexity. As pooled liquids form equipotential surfaces, coastlines are equivalent to topographic contour lines. The complexity of a coastline can therefore be related to the complexity of the surface it is embedded in through fractal theory. Thus, a statistical characterization of Titan's topography can be extracted through analysis of these shorelines. We have carried out this analysis for coastlines on Titan and have related the coastline roughness parameters to topography parameters for Titan's landscape. In this study, we used projected Cassini Radar observations (resolution of about 350m/pixel near the centre of the swath). The shorelines of 290 of these North Polar Titanian lakes have been manually outlined at the full resolution of the dataset. Their fractal dimensions were calculated via two methods: the ruler method and the box-counting method. Our results show Titan's coastlines do exhibit fractal properties with fractal dimensions comparable to published estimates of the terrestrial coastlines of Britain and Germany. Such high values of this roughness parameter show that Titanian coastlines are intricate by terrestrial standards, which implies a rugged landscape. We will report on this statistical characterization of Titan's topography and spatial variations in landscape roughness.

  9. Linking topography to tonotopy in the mouse auditory thalamocortical circuit

    PubMed Central

    Hackett, Troy A.; Barkat, Tania Rinaldi; OBrien, Barbara MJ.; Hensch, Takao K.; Polley, Daniel B.

    2011-01-01

    The mouse sensory neocortex is reported to lack several hallmark features of topographic organization such as ocular dominance and orientation columns in primary visual cortex or fine-scale tonotopy in primary auditory cortex (AI). Here, we re-examined the question of auditory functional topography by aligning ultra-dense receptive field maps from the auditory cortex and thalamus of the mouse in vivo with the neural circuitry contained in the auditory thalamocortical slice in vitro. We observed precisely organized tonotopic maps of best frequency (BF) in the middle layers of AI and the anterior auditory field (AAF) as well as in ventral and medial divisions of the medial geniculate body (MGBv, MGBm). Tracer injections into distinct zones of the BF map in AI retrogradely labeled topographically organized MGBv projections and weaker, mixed projections from MGBm. Stimulating MGBv along the tonotopic axis in the slice produced an orderly shift of voltage-sensitive dye (VSD) signals along the AI tonotopic axis, demonstrating topography in the mouse thalamocortical circuit that is preserved in the slice. However, compared to BF maps of neuronal spiking activity, the topographic order of sub-threshold VSD maps was reduced in layer IV and even further degraded in layer II/III. Therefore, the precision of AI topography varies according to the source and layer of the mapping signal. Our findings further bridge the gap between in vivo and in vitro approaches for the detailed cellular study of auditory thalamocortical circuit organization and plasticity in the genetically tractable mouse model. PMID:21414920

  10. Development of topography in 3-D continental-collision models

    NASA Astrophysics Data System (ADS)

    Pusok, A. E.; Kaus, Boris J. P.

    2015-05-01

    Understanding the formation and evolution of high mountain belts, such as the Himalayas and the adjacent Tibetan Plateau, has been the focus of many tectonic and numerical models. Here we employ 3-D numerical simulations to investigate the role that subduction, collision, and indentation play on lithosphere dynamics at convergent margins, and to analyze the conditions under which large topographic plateaus can form in an integrated lithospheric and upper mantle-scale model. Distinct dynamics are obtained for the oceanic subduction side (trench retreat, slab rollback) and the continental-collision side (trench advance, slab detachment, topographic uplift, lateral extrusion). We show that slab pull alone is insufficient to generate high topography in the upper plate, and that external forcing and the presence of strong blocks such as the Tarim Basin are necessary to create and shape anomalously high topographic fronts and plateaus. Moreover, scaling is used to predict four different modes of surface expression in continental-collision models: (I) low-amplitude homogeneous shortening, (II) high-amplitude homogeneous shortening, (III) Alpine-type topography with topographic front and low plateau, and (IV) Tibet-Himalaya-type topography with topographic front and high plateau. Results of semianalytical models suggest that the Argand number governs the formation of high topographic fronts, while the amplitude of plateaus is controlled by the initial buoyancy ratio of the upper plate. Applying these results to natural examples, we show that the Alps belong to regime (III), the Himalaya-Tibet to regime (IV), whereas the Andes-Altiplano fall at the boundary between regimes (III) and (IV).

  11. Topography and biological noise determine acoustic detectability on coral reefs

    NASA Astrophysics Data System (ADS)

    Cagua, E. F.; Berumen, M. L.; Tyler, E. H. M.

    2013-12-01

    Acoustic telemetry is an increasingly common tool for studying the movement patterns, behavior and site fidelity of marine organisms, but to accurately interpret acoustic data, the variability, periodicity and range of detectability between acoustic tags and receivers must be understood. The relative and interactive effects of topography with biological and environmental noise have not been quantified on coral reefs. We conduct two long-term range tests (1- and 4-month duration) on two different reef types in the central Red Sea to determine the relative effect of distance, depth, topography, time of day, wind, lunar phase, sea surface temperature and thermocline on detection probability. Detectability, as expected, declines with increasing distance between tags and receivers, and we find average detection ranges of 530 and 120 m, using V16 and V13 tags, respectively, but the topography of the reef can significantly modify this relationship, reducing the range by ~70 %, even when tags and receivers are in line-of-sight. Analyses that assume a relationship between distance and detections must therefore be used with care. Nighttime detection range was consistently reduced in both locations, and detections varied by lunar phase in the 4-month test, suggesting a strong influence of biological noise (reducing detection probability up to 30 %), notably more influential than other environmental noises, including wind-driven noise, which is normally considered important in open-water environments. Analysis of detections should be corrected in consideration of the diel patterns we find, and range tests or sentinel tags should be used for more than 1 month to quantify potential changes due to lunar phase. Some studies assume that the most usual factor limiting detection range is weather-related noise; this cannot be extrapolated to coral reefs.

  12. Influence of subduction history on South American topography

    NASA Astrophysics Data System (ADS)

    Flament, Nicolas; Gurnis, Michael; Mller, R. Dietmar; Bower, Dan J.; Husson, Laurent

    2015-11-01

    The Cenozoic evolution of South American topography is marked by episodes of large-scale uplift and subsidence not readily explained by lithospheric deformation. The drying up of the inland Pebas system, the drainage reversal of the Amazon river, the uplift of the Sierras Pampeanas and the uplift of Patagonia have all been linked to the evolution of mantle flow since the Miocene in separate studies. Here we investigate the evolution of long-wavelength South American topography as a function of subduction history in a time-dependent global geodynamic model. This model is shown to be consistent with these inferred changes, as well as with the migration of the Chaco foreland basin depocentre, that we partly attribute to the inboard migration of subduction resulting from Andean mountain building. We suggest that the history of subduction along South America has had an important influence on the evolution of the topography of the continent because time-dependent mantle flow models are consistent with the history of vertical motions as constrained by the geological record at four distant areas over a whole continent. Testing alternative subduction scenarios reveals flat slab segments are necessary to reconcile inferred Miocene shorelines with a simple model paleogeography. As recently suggested, we find that the flattening of a subduction zone results in dynamic uplift between the leading edge of the flat slab segment and the trench, and in a wave of dynamic subsidence associated with the inboard migration of the leading edge of flat subduction. For example, the flattening of the Peruvian subduction contributed to the demise of Pebas shallow-water sedimentation, while continental-scale tilting also contributed to the drainage reversal of the Amazon River. The best correlation to P-wave tomography models for the Peruvian flat slab segment is obtained for a case when the asthenosphere, here considered to be 150 km thick and 10 times less viscous than the upper mantle, is restricted to the oceanic domain.

  13. The role of topography in geodetic gravity field modelling

    NASA Technical Reports Server (NTRS)

    Forsberg, R.; Sideris, M. G.

    1989-01-01

    Masses associated with the topography, bathymetry, and its isostatic compensation are a dominant source of gravity field variations, especially at shorter wavelengths. On global scales the topographic/isostatic effects are also significant, except for the lowest harmonics. In practice, though, global effects need not be taken into account as such effects are included in the coefficients of the geopotential reference fields. On local scales, the short-wavelength gravity variations due to the topography may, in rugged terrain, be an order of magnitude larger than other effects. In such cases, explicit or implicit terrain reduction procedures are mandatory in order to obtain good prediction results. Such effects may be computed by space-domain integration or by fast Fourier transformation (FFT) methods. Numerical examples are given for areas of the Canadian Rockies. In principle, good knowledge of the topographic densities is required to produce the smoothest residual field. Densities may be determined from sample measurements or by gravimetric means, but both are somewhat troublesome methods in practice. The use of a standard density, e.g., 2.67 g/cu cm, may often yield satisfactory results and may be put within a consistent theoretical framework. The independence of density assumptions is the key point of the classical Molodensky approach to the geodetic boundary value problem. The Molodensky solutions take into account that land gravity field observations are done on a non-level surface. Molodensky's problem may be solved by integral expansions or more effective FFT methods, but the solution should not be intermixed with the use of terrain reductions. The methods are actually complimentary and may both be required in order to obtain the smoothest possible signal, least prone to aliasing and other effects coming from sparse data coverage, typical of rugged topography.

  14. The topography, gravity, and tectonics of the terrestrial planets

    NASA Astrophysics Data System (ADS)

    Ritzer, Jason Andreas

    The topography and gravity of some of the solid earth bodies in our solar system including the Moon, Mercury, and Mars are used to investigate the density structure, lithospheric structure and resultant tectonic deformation. The difficulties in representing the gravitational field based on satellite data are explored including possible solutions including a change of representational basis function. The problem of representing the gravitational field based on non-uniform data distributions is addressed. Early results and expected returns from the MESSENGER mission to Mercury including compressional tectonics are studied.

  15. Dynamic wetting and spreading and the role of topography.

    PubMed

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

    2009-11-18

    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

  16. Topography of the Moon from the Clementine Lidar

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

    Range measurements from the lidar instrument carried aboard the Clementine spacecraft have been used to produce an accurate global topographic model of the Moon. This paper discusses the function of the lidar; the acquisition, processing, and filtering of observations to produce a global topographic model; and the determination of parameters that define the fundamental shape of the Moon. Our topographic model: a 72nd degree and order spherical harmonic expansion of lunar radii, is designated Goddard Lunar Topography Model 2 (GLTM 2). This topographic field has an absolute vertical accuracy of approximately 100 m and a spatial resolution of 2.5 deg. The field shows that the Moon can be described as a sphere with maximum positive and negative deviations of approx. 8 km, both occurring on the farside, in the areas of the Korolev and South Pole-Aitken (S.P.-Aitken) basins. The amplitude spectrum of the topography shows more power at longer wavelengths as compared to previous models, owing to more complete sampling of the surface, particularly the farside. A comparison of elevations derived from the Clementine lidar to control point elevations from the Apollo laser altimeters indicates that measured relative topographic heights generally agree to within approx. 200 in over the maria. While the major axis of the lunar gravity field is aligned in the Earth-Moon direction, the major axis of topography is displaced from this line by approximately 10 deg to the cast and intersects the farside 24 deg north of the equator. The magnitude of impact basin topography is greater than the lunar flattening (approx. 2 km) and equatorial ellipticity (approx. 800 m), which imposes a significant challenge to interpreting the lunar figure. The floors of mare basins are shown to lie close to an equipotential surface, while the floors of unflooded large basins, except for S.P.-Aitken, lie above this equipotential. The radii of basin floors are thus consistent with a hydrostatic mechanism for the absence of significant farside maria except for S.P.-Aitken, whose depth and lack of mare require significant internal compositional and/or thermal heterogeneity. A macroscale surface roughness map shows that roughness at length scales of 10(exp 1) - 10(exp 2) km correlates with elevation and surface age.

  17. X-ray topography study of complex silicon microcircuits

    NASA Technical Reports Server (NTRS)

    Parker, D. L.

    1981-01-01

    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 that in changing any existing process or developing a new process the technique can be of significant benefit.

  18. Spherical harmonic expansion of the Levitus Sea surface topography

    NASA Technical Reports Server (NTRS)

    Engelis, Theodossios

    1987-01-01

    Prior information for the stationary sea surface topography (SST) may be needed in altimetric solutions that intend to simultaneously improve the gravity field and determine the SST. For this purpose the oceanographically derived SST estimates are represented by a spherical harmonic expansion. The spherical harmonic coefficients are computed from a least squares adjustment of the data covering the majority of the oceanic regions of the world. Several tests are made to determine the optimum maximum degree of solution and the best configuration of the geometry of the data in order to obtain a solution that fits the data and also provides a good spectral representation of the SST.

  19. Mars ultraviolet reflectance compared with imaging, topography and geology

    NASA Astrophysics Data System (ADS)

    Simmons, K. E.; Mankoff, K. D.; Hendrix, A. R.; Barth, C. A.

    2003-04-01

    We compare ultraviolet reflectance spectra from the Mariner Mars 1971 (MM71) Ultraviolet Spectrometer (UVS) with imaging data from the Viking Mars Digital Image Model (MDIM), with surface topography from the Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA), and with geology from the USGS Survey Atlas of Mars digital maps. We use a new web-accessible database of MM71 UVS Reflectances and two software tools: 1) a surface and atmosphere database visualization tool called Albatross and 2) a web-based Mars data comparison tool called MDC. See http://lasp.colorado.edu/software_tools/. We present several examples, including the northern polar region and Lyot Crater.

  20. Evolution of topography on comets. II - Icy craters and trenches

    NASA Technical Reports Server (NTRS)

    Colwell, Joshua E.; Jakosky, Bruce M.; Sandor, Bradford J.; Stern, S. Alan

    1990-01-01

    The determination of the effects of topography on the sublimation rates of comets and other icy bodies is presently approached via a model of ice heating and sublimation from topographical features. The energy balance equation is solved for cylindrical trenches and spherical craters; the model encompasses shadowing, solar heating, the trapping of thermal radiation and sublimed gas molecules, and reflection of sunlight within the cavity. Generally, an enhancement is found in the net sublimation rate for trenches and craters farther from the sun than some critical distance which depends on the albedo.

  1. EAARL Topography-Vicksburg National Military Park 2007: First Surface

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Segura, Martha; Yates, Xan

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first-surface (FS) 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), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Vicksburg National Military Park in Mississippi, acquired on September 12, 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 presurvey 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 used routinely 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.

  2. EAARL Topography - Vicksburg National Military Park 2008: Bare Earth

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Segura, Martha; Yates, Xan

    2008-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) 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), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Vicksburg National Military Park in Mississippi, acquired on March 6, 2008. 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 presurvey 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 used routinely 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.

  3. EAARL Coastal Topography--Cape Canaveral, Florida, 2009: First Surface

    USGS Publications Warehouse

    Bonisteel-Cormier, J.M.; Nayegandhi, Amar; Plant, Nathaniel; Wright, C.W.; Nagle, D.B.; Serafin, K.S.; Klipp, E.S.

    2011-01-01

    These remotely sensed, geographically referenced elevation measurements of lidar-derived first-surface (FS) topography datasets were produced collaboratively by the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Kennedy Space Center, FL. This project provides highly detailed and accurate datasets of a portion of the eastern Florida coastline beachface, acquired on May 28, 2009. 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 multispectral color-infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine aircraft, but the instrument was deployed on a Pilatus PC-6. 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 presurvey 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 used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the "bare earth" under vegetation from a point cloud of last return elevations.

  4. Applications of laser ranging to ocean, ice, and land topography

    NASA Technical Reports Server (NTRS)

    Degnan, John J.

    1991-01-01

    The current status and some future applications of satellite laser ranging (SLR) are briefly reviewed. The demonstrated subcentimeter precision of ground-based SLR systems is attracting new users, particularly, in the area of high-resolution ocean, ice, and land topography. Future airborne or spaceborne SLR system will not only provide topographic data with a horizontal and vertical resolution never achieved previously, but, in addition, ground-based SLR systems, via precise tracking of spaceborne microwave and laser altimeters, will permit the expression of the topographic surface in a common geocentric reference frame.

  5. EAARL Topography - George Washington Birthplace National Monument 2008

    USGS Publications Warehouse

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

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) and first surface (FS) 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 the George Washington Birthplace National Monument in Virginia, acquired on March 26, 2008. 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 presurvey 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.

  6. EAARL Coastal Topography - Northeast Barrier Islands 2007: Bare Earth

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Wright, C. Wayne; Yates, Xan; Bonisteel, Jamie M.

    2008-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the northeast coastal barrier islands in New York and New Jersey, acquired April 29-30 and May 15-16, 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 presurvey 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.

  7. EAARL Coastal Topography - Northeast Barrier Islands 2007: First Surface

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Sallenger, A.H.; Wright, C. Wayne; Yates, Xan; Bonisteel, Jamie M.

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the northeast coastal barrier islands in New York and New Jersey, acquired April 29-30 and May 15-16, 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 presurvey 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.

  8. EAARL Submerged Topography - U.S. Virgin Islands 2003

    USGS Publications Warehouse

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

    2008-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived submerged 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), South Florida-Caribbean Network, Miami, FL; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate bathymetric datasets of a portion of the U.S. Virgin Islands, acquired on April 21, 23, and 30, May 2, and June 14 and 17, 2003. 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 presurvey 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 used routinely 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.

  9. EAARL Coastal Topography-Pearl River Delta 2008: First Surface

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Miner, Michael D.; Michael, D.; Yates, Xan; Bonisteel, Jamie M.

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the University of New Orleans (UNO), Pontchartrain Institute for Environmental Sciences (PIES), New Orleans, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Pearl River Delta in Louisiana and Mississippi, acquired March 9-11, 2008. 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 presurvey 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 used routinely 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.

  10. EAARL Coastal Topography-Chandeleur Islands, Louisiana, 2010: Bare Earth

    USGS Publications Warehouse

    Nayegandhi, Amar; Bonisteel-Cormier, Jamie M.; Brock, John C.; Sallenger, A.H.; Wright, C. Wayne; Nagle, David B.; Vivekanandan, Saisudha; Yates, Xan; Klipp, Emily S.

    2010-01-01

    These remotely sensed, geographically referenced elevation measurements of lidar-derived bare-earth (BE) and submerged topography datasets were produced collaboratively by the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Chandeleur Islands, acquired March 3, 2010. 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 multispectral color-infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter 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 presurvey 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 used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations. For more information about similar projects, please visit the Decision Support for Coastal Science and Management website.

  11. EAARL Topography - Jean Lafitte National Historical Park and Preserve 2006

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Segura, Martha; Yates, Xan

    2008-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) and bare earth (BE) 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), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Jean Lafitte National Historical Park and Preserve in Louisiana, acquired on September 22, 2006. 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 presurvey 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 used routinely 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.

  12. EAARL Topography - Natchez Trace Parkway 2007: First Surface

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Segura, Martha; Yates, Xan

    2008-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) 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), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Natchez Trace Parkway in Mississippi, acquired on September 14, 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 presurvey 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 used routinely 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.

  13. EAARL Coastal Topography - Northern Gulf of Mexico, 2007: Bare Earth

    USGS Publications Warehouse

    Smith, Kathryn E.L.; Nayegandhi, Amar; Wright, C. Wayne; Bonisteel, Jamie M.; Brock, John C.

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) 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), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. The purpose of this project is to provide highly detailed and accurate datasets of select barrier islands and peninsular regions of Louisiana, Mississippi, Alabama, and Florida, acquired on June 27-30, 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 presurvey 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 used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

  14. EAARL Coastal Topography - Fire Island National Seashore 2007

    USGS Publications Warehouse

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

    2008-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) and bare earth (BE) 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 Fire Island National Seashore in New York, acquired on April 29-30 and May 15-16, 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.

  15. EAARL Coastal Topography-Pearl River Delta 2008: Bare Earth

    USGS Publications Warehouse

    Nayegandhi, Amar; Brock, John C.; Wright, C. Wayne; Miner, Michael D.; Yates, Xan; Bonisteel, Jamie M.

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the University of New Orleans (UNO), Pontchartrain Institute for Environmental Sciences (PIES), New Orleans, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Pearl River Delta in Louisiana and Mississippi, acquired March 9-11, 2008. 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 presurvey 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 used routinely 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.

  16. Experimental and numerical modeling of wind flow over complex topography

    NASA Astrophysics Data System (ADS)

    Rasouli, Ashkan

    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).

  17. Dynamic evaluation of facial palsy by moire topography video

    NASA Astrophysics Data System (ADS)

    Yuen, Koji; Inokuchi, Ikuo; Maeta, Manabu; Kawakami, Shinichiro; Masuda, Yu

    1994-02-01

    Several visual assessment methods have been proposed for evaluating facial nerve function. They are of value clinically, but they have drawbacks when objective, quantitative, and reproducible assessment is required. To solve these problems, we used moire topography, which helps visualize information in three dimensions. We previously reported that one could evaluate the severity of facial palsy by observing characteristic patterns of the moire strips produced by facial movement. Accordingly, we developed a new form of the dynamic evaluation by recording the dynamic changes in moire strip patterns on the face on a videotape.

  18. Anelasticity explains topography associated with Basin and Range normal faulting

    NASA Astrophysics Data System (ADS)

    Hassani, R.; Chry, J.

    1996-12-01

    Topography associated with normal faulting in the Basin and Range (western United States) is usually modeled as a flexure of a broken elastic plate. However, modeled effective rigidities are usually 100 times lower than the rigidity deduced from upper-crustal thickness. This discrepancy may be related to a significant anelastic deformation, which we explore through numerical modeling. Because experimental rock rheology evidences a pressure-dependent yield stress beyond the elastic limit in crustal rocks, we made a finite element model that accounts for such a crustal rheology and also for the frictional behavior of an embedded high-angle fault. Resulting topography after extension is similar to that obtained from a thin elastic plate model; however, the corresponding strain pattern differs. First, the footwall rotates in a rigid fashion over a width of 15 km that matches the typical size of uplifted Basin and Range blocks. Second, hanging-wall subsidence results from a significant horizontal extension and rotation of the crust. We suggest that plastic deformation in the deep part of the footwall could trigger the development of a new high-angle fault with a fault spacing that matches Basin and Range structure.

  19. Tutorial on platform for optical topography analysis tools.

    PubMed

    Sutoko, Stephanie; Sato, Hiroki; Maki, Atsushi; Kiguchi, Masashi; Hirabayashi, Yukiko; Atsumori, Hirokazu; Obata, Akiko; Funane, Tsukasa; Katura, Takusige

    2016-01-01

    Optical topography/functional near-infrared spectroscopy (OT/fNIRS) is a functional imaging technique that noninvasively measures cerebral hemoglobin concentration changes caused by neural activities. The fNIRS method has been extensively implemented to understand the brain activity in many applications, such as neurodisorder diagnosis and treatment, cognitive psychology, and psychiatric status evaluation. To assist users in analyzing fNIRS data with various application purposes, we developed a software called platform for optical topography analysis tools (POTATo). We explain how to handle and analyze fNIRS data in the POTATo package and systematically describe domain preparation, temporal preprocessing, functional signal extraction, statistical analysis, and data/result visualization for a practical example of working memory tasks. This example is expected to give clear insight in analyzing data using POTATo. The results specifically show the activated dorsolateral prefrontal cortex is consistent with previous studies. This emphasizes analysis robustness, which is required for validating decent preprocessing and functional signal interpretation. POTATo also provides a self-developed plug-in feature allowing users to create their own functions and incorporate them with established POTATo functions. With this feature, we continuously encourage users to improve fNIRS analysis methods. We also address the complications and resolving opportunities in signal analysis. PMID:26788547

  20. Topography and Areal Organization of Mouse Visual Cortex

    PubMed Central

    Garrett, Marina E.; Nauhaus, Ian; Marshel, James H.

    2014-01-01

    To guide future experiments aimed at understanding the mouse visual system, it is essential that we have a solid handle on the global topography of visual cortical areas. Ideally, the method used to measure cortical topography is objective, robust, and simple enough to guide subsequent targeting of visual areas in each subject. We developed an automated method that uses retinotopic maps of mouse visual cortex obtained with intrinsic signal imaging (Schuett et al., 2002; Kalatsky and Stryker, 2003; Marshel et al., 2011) and applies an algorithm to automatically identify cortical regions that satisfy a set of quantifiable criteria for what constitutes a visual area. This approach facilitated detailed parcellation of mouse visual cortex, delineating nine known areas (primary visual cortex, lateromedial area, anterolateral area, rostrolateral area, anteromedial area, posteromedial area, laterointermediate area, posterior area, and postrhinal area), and revealing two additional areas that have not been previously described as visuotopically mapped in mice (laterolateral anterior area and medial area). Using the topographic maps and defined area boundaries from each animal, we characterized several features of map organization, including variability in area position, area size, visual field coverage, and cortical magnification. We demonstrate that higher areas in mice often have representations that are incomplete or biased toward particular regions of visual space, suggestive of specializations for processing specific types of information about the environment. This work provides a comprehensive description of mouse visuotopic organization and describes essential tools for accurate functional localization of visual areas. PMID:25209296

  1. Tropical Pacific response to continental ice sheet topography

    NASA Astrophysics Data System (ADS)

    Lee, Shih-Yu; Chiang, John C. H.; Chang, Ping

    2015-05-01

    The last glacial maximum was marked by maximum land ice extent and lowest greenhouse gases concentration during the last ice age. We explore the impact of glacial continental ice sheet topography on the large-scale tropical ocean-atmosphere climate, in particular the tropical Pacific, in an intermediate complexity coupled model. Increasing the thickness of continental ice sheets causes a southward displaced Pacific Intertropical Convergence Zone (ITCZ) and a strengthening (weakening) of northern (southern) hemisphere winter Hadley cell. The equatorial zonal sea surface temperature gradient weakened with an increased continental ice sheets thickness, the reduction being caused by cooling in the western equatorial Pacific and warming in the eastern equatorial Pacific. The evolution of the tropical climate with changing ice thickness has distinct quasi-linear and nonlinear parts. While the linear part is a direct response to the ice topographic changes, the nonlinear part was a result of the tropical thermocline adjustment. Our analysis of a fully-coupled transient deglacial simulation strongly indicates the dominant role of ice sheet topography in determining the deglacial evolution of the simulated Pacific climate. The thickness of continental ice sheet, separate from ice albedo effect, has significant impact on the tropical ocean-atmosphere climate in particular with the meridional displacement in the Pacific ITCZ. The altered circulation states seen in the model may aid understanding of the relationship between tropical and high-latitude climate records in glacial-interglacial cycles.

  2. X-Ray Topography Techniques for Defect Characterization of Crystals

    NASA Astrophysics Data System (ADS)

    Raghothamachar, Balaji; Dudley, Michael; Dhanaraj, Govindhan

    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.

  3. Lunar Topography: Results from the Lunar Orbiter Laser Altimeter

    NASA Technical Reports Server (NTRS)

    Neumann, Gregory; Smith, David E.; Zuber, Maria T.; Mazarico, Erwan

    2012-01-01

    The Lunar Orbiter Laser Altimeter (LOLA) onboard the Lunar Reconnaissance Orbiter (LRO) has been operating nearly continuously since July 2009, accumulating over 6 billion measurements from more than 2 billion in-orbit laser shots. LRO's near-polar orbit results in very high data density in the immediate vicinity of the lunar poles, with full coverage at the equator from more than 12000 orbital tracks averaging less than 1 km in spacing at the equator. LRO has obtained a global geodetic model of the lunar topography with 50-meter horizontal and 1-m radial accuracy in a lunar center-of-mass coordinate system, with profiles of topography at 20-m horizontal resolution, and 0.1-m vertical precision. LOLA also provides measurements of reflectivity and surface roughness down to its 5-m laser spot size. With these data LOLA has measured the shape of all lunar craters 20 km and larger. In the proposed extended mission commencing late in 2012, LOLA will concentrate observations in the Southern Hemisphere, improving the density of the polar coverage to nearly 10-m pixel resolution and accuracy to better than 20 m total position error. Uses for these data include mission planning and targeting, illumination studies, geodetic control of images, as well as lunar geology and geophysics. Further improvements in geodetic accuracy are anticipated from the use of re ned gravity fields after the successful completion of the Gravity Recovery and Interior Laboratory (GRAIL) mission in 2012.

  4. Multiview hyperspectral topography of tissue structural and functional characteristics

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Huang, Jiwei; Zhang, Shiwu; Xu, Ronald X.

    2016-01-01

    Accurate and in vivo characterization of structural, functional, and molecular characteristics of biological tissue will facilitate quantitative diagnosis, therapeutic guidance, and outcome assessment in many clinical applications, such as wound healing, cancer surgery, and organ transplantation. We introduced and tested a multiview hyperspectral imaging technique for noninvasive topographic imaging of cutaneous wound oxygenation. The technique integrated a multiview module and a hyperspectral module in a single portable unit. Four plane mirrors were cohered to form a multiview reflective mirror set with a rectangular cross section. The mirror set was placed between a hyperspectral camera and the target biological tissue. For a single image acquisition task, a hyperspectral data cube with five views was obtained. The five-view hyperspectral image consisted of a main objective image and four reflective images. Three-dimensional (3-D) topography of the scene was achieved by correlating the matching pixels between the objective image and the reflective images. 3-D mapping of tissue oxygenation was achieved using a hyperspectral oxygenation algorithm. The multiview hyperspectral imaging technique was validated in a wound model, a tissue-simulating blood phantom, and in vivo biological tissue. The experimental results demonstrated the technical feasibility of using multiview hyperspectral imaging for 3-D topography of tissue functional properties.

  5. Multiview hyperspectral topography of tissue structural and functional characteristics

    NASA Astrophysics Data System (ADS)

    Zhang, Shiwu; Liu, Peng; Huang, Jiwei; Xu, Ronald

    2012-12-01

    Accurate and in vivo characterization of structural, functional, and molecular characteristics of biological tissue will facilitate quantitative diagnosis, therapeutic guidance, and outcome assessment in many clinical applications, such as wound healing, cancer surgery, and organ transplantation. However, many clinical imaging systems have limitations and fail to provide noninvasive, real time, and quantitative assessment of biological tissue in an operation room. To overcome these limitations, we developed and tested a multiview hyperspectral imaging system. The multiview hyperspectral imaging system integrated the multiview and the hyperspectral imaging techniques in a single portable unit. Four plane mirrors are cohered together as a multiview reflective mirror set with a rectangular cross section. The multiview reflective mirror set was placed between a hyperspectral camera and the measured biological tissue. For a single image acquisition task, a hyperspectral data cube with five views was obtained. The five-view hyperspectral image consisted of a main objective image and four reflective images. Three-dimensional topography of the scene was achieved by correlating the matching pixels between the objective image and the reflective images. Three-dimensional mapping of tissue oxygenation was achieved using a hyperspectral oxygenation algorithm. The multiview hyperspectral imaging technique is currently under quantitative validation in a wound model, a tissue-simulating blood phantom, and an in vivo biological tissue model. The preliminary results have demonstrated the technical feasibility of using multiview hyperspectral imaging for three-dimensional topography of tissue functional properties.

  6. EAARL submarine topography: Florida Keys National Marine Sanctuary

    USGS Publications Warehouse

    Brock, John C.; Wright, C. Wayne; Nayegandhi, Amar; Woolard, Jason; Patterson, Matt; Wilson, Iris; Travers, Laurinda J.

    2007-01-01

    This Web site contains 46 Lidar-derived submarine topography maps and GIS files for the Florida Keys National Marine Sanctuary. These Lidar-derived submarine topographic maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Oceanic and Atmospheric Administration (NOAA), Remote Sensing Division, 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 within 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 coastal resource managers.

  7. Sniffing-related motor cortical potential: topography and possible generators.

    PubMed

    Jeran, Judita; Koritnik, Bla; Zidar, Ignac; Beli?, Ale; Zidar, Janez

    2013-01-15

    This study estimated the whole-scalp topography and possible generators of the cortical potential associated with volitional self-paced inspirations (sniffs). In 17 healthy subjects we recorded a 32-channel electroencephalogram (EEG) during sniffing, for comparison during finger flexions. We averaged the EEG with respect to movement onset, and performed current source density and principal component analysis on the grand averaged data. We identified an early negative sniffing-related cortical potential starting ?1.5s before movement at the vertex, which, in its time-course and dipole orientation, closely resembled Bereitshaftspotential preceding finger flexions. Around the movement onset, its topography became unique with three negative current sources: one at the vertex, and two bilaterally over the fronto-temporal derivations. We conclude that sequential cortical activation in preparation for sniffing is similar to other volitional movements. The current sources at sniff onset at the vertex likely reflect somatotopic motor representation of the diaphragm, neck and intercostal muscles, whereas current sources over fronto-temporal derivations likely reflect the somatotopic representation of the orofacial muscles. PMID:23078972

  8. Minimal erosion of Arctic alpine topography during late Quaternary glaciation

    NASA Astrophysics Data System (ADS)

    Gjermundsen, Endre F.; Briner, Jason P.; Akar, Naki; Foros, Jrn; Kubik, Peter W.; Salvigsen, Otto; Hormes, Anne

    2015-10-01

    The alpine topography observed in many mountainous regions is thought to have formed during repeated glaciations of the Quaternary period. Before this time, landscapes had much less relief. However, the spatial patterns and rates of Quaternary exhumation at high latitudes--where cold-based glaciers may protect rather than erode landscapes--are not fully quantified. Here we determine the exposure and burial histories of rock samples from eight summits of steep alpine peaks in northwestern Svalbard (79.5 N) using analyses of 10Be and 26Al concentrations. We find that the summits have been preserved for at least the past one million years. The antiquity of Svalbards alpine landscape is supported by the preservation of sediments older than one million years along a fjord valley, which suggests that both mountain summits and low-elevation landscapes experienced very low erosion rates over the past million years. Our findings support the establishment of northwestern Svalbards alpine topography during the early Quaternary. We suggest that, as the Quaternary ice age progressed, glacial erosion in the Arctic became inefficient and confined to ice streams, and high-relief alpine landscapes were preserved by minimally erosive glacier armour.

  9. Feasibility of skin surface elastography by tracking skin surface topography

    NASA Astrophysics Data System (ADS)

    Coutts, Louise V.; Miller, Naomi R.; Harland, Christopher C.; Bamber, Jeffrey C.

    2013-12-01

    Recent advances have led to a multitude of image modalities being used for visualization of tissue stiffness. High-resolution images of tissue stiffness are desirable, as they have the potential to provide useful diagnostic information. A noncontact optical imaging method has the attractions of low cost, simplicity, and utility when skin contact is undesirable. However, previous optical techniques have required the application of paint or ink to the surface of the skin and so have required contact. Therefore, the present study assessed the feasibility of tracking skin surface topography to produce elastograms. The study showed, by analyzing a variety of silicone skin surface replicas from various body sites of subjects of different ages, that skin surface elastography by tracking surface topography would be feasible. The study further showed that the quality of the strain images can be optimized by measuring skin line pattern frequency. Skin samples with high skin line frequency will achieve best spatial resolution, in the order of 1 mm, comparable to contact techniques reported previously. A mechanically inhomogeneous silicone replica was then imaged, illustrating the technique's ability to detect strain contrast. Finally, the feasibility of implementing the technique in vivo was illustrated using a single pigmented skin lesion.

  10. Rejuvenation of Appalachian topography due to subsidence induced differential erosion

    NASA Astrophysics Data System (ADS)

    Liu, L.

    2014-12-01

    In ancient orogens, such as the Appalachian Mountains in the eastern United States, the difference between the high and low pointstopographic reliefcan continue to increase long after the tectonic forces that created the range have become inactive. Climatic forcing and mantle-induced dynamic uplift are proposed to drive formation of relief, but clear evidence is lacking in the Appalachian Mountains. Here I use a numerical simulation of dynamic topography in North America, combined with reconstructions of the sedimentation history from the Gulf of Mexico, to show that rejuvenation of topographic relief in the Appalachian Mountains since the Palaeogene period could have been caused by mantle-induced dynamic subsidence associated with sinking of the subducted Farallon slab. Specifically, I show that patterns of continental erosion and the eastward migration of sediment deposition centres in the Gulf of Mexico closely follow the locus of predicted dynamic subsidence. Furthermore, pulses of rapid sediment deposition in the Gulf of Mexico and western Atlantic correlate with enhanced erosion in the Appalachian Mountains during the Miocene epoch, caused by dynamic tilting of the continent. Calculations show that such subsidence-induced differential erosion caused flexural-isostatic adjustments of Appalachian topography that led to the development of both relief and elevation. I propose that dynamically induced continental tilting may provide a mechanism for topographic rejuvenation in ancient orogens.

  11. A study on Ganymede's surface topography: Perspectives for radar sounding

    NASA Astrophysics Data System (ADS)

    Berquin, Y.; Kofman, W.; Herique, A.; Alberti, G.; Beck, P.

    2013-03-01

    Radar sounding of Jovian icy satellites has great potential to address specific science questions such as the presence of subsurface liquid water. Radargrams acquired over Mars polar caps allow observing clear echoes up to kilometers depth. However, Jovian icy satellites display dramatically different surface topographies. In order to assess possible issues arising from such surface topographies on radar sounding, we performed a study on different DEMs (Digital Elevation Models) obtained on Ganymede. Topographic data are derived using stereo and photoclinometric analysis of Galileo and Voyager images at resolutions of 16-629 m. Main results are presented in this paper. Overall we found that Ganymede's surface is quite rough, with mean slopes at 630 m scale varying from 3.5° to 8°, smoothest terrains being found within sulcii. This will be a major challenge for the design of radar sounders and parameters should be chosen accordingly in order to correctly sound this planetary body. Previous studies have shown similar concern for Europa.

  12. Mapping the global topography of the cost function in STELLOPT

    NASA Astrophysics Data System (ADS)

    Lucia, M.; Mynick, H. E.; Pomphrey, N.

    2011-10-01

    Stellarator designs have long been optimized for reduced neoclassical transport, but optimization for reduced turbulent transport is a relatively nascent research thrust. Recent work has addressed this ``turbulent optimization'' by using the GENE/GIST nonlinear gyrokinetic code and the STELLOPT stellarator optimization code. That work demonstrated that STELLOPT can produce stellarator designs that reduce the turbulent transport without adversely affecting other design metrics. STELLOPT utilizes a Levenberg-Marquardt (LM) algorithm to find a local minimum of a cost function in a shape space z of coefficients that define the plasma boundary. However, a visualization of the topography of the cost function in z space might reveal a lower global minimum and provide insight into why the LM algorithm missed it. The current work uses STELLOPT to provide this capability, replacing its LM algorithm with one that produces maps of the wider topography of the cost function. Analysis of these maps will be used to gain insight into the properties of the studied design configurations and to identify possible improvements to STELLOPT's optimization algorithm. Supported by U.S. DOE contract DE-AC02-09CH11466 and by U.S. DOD NDSEG fellowship.

  13. Geophysical, petrological and mineral physics constraints on Earth's surface topography

    NASA Astrophysics Data System (ADS)

    Guerri, Mattia; Cammarano, Fabio; Tackley, Paul J.

    2015-04-01

    Earth's surface topography is controlled by isostatically compensated density variations within the lithosphere, but dynamic topography - i.e. the topography due to adjustment of surface to mantle convection - is an important component, specially at a global scale. In order to separate these two components it is fundamental to estimate crustal and mantle density structure and rheological properties. Usually, crustal density is constrained from interpretation of available seismic data (mostly VP profiles) based on empirical relationships such those in Brocher [2005]. Mantle density structure is inferred from seismic tomography models. Constant coefficients are used to interpret seismic velocity anomalies in density anomalies. These simplified methods are unable to model the effects that pressure and temperature variations have on mineralogical assemblage and physical properties. Our approach is based on a multidisciplinary method that involves geophysical observables, mineral physics constraints, and petrological data. Mantle density is based on the thermal interpretation of global seismic tomography models assuming various compositional structures, as in Cammarano et al. [2011]. We further constrain the top 150 km by including heat-flow data and considering the thermal evolution of the oceanic lithosphere. Crustal density is calculated as in Guerri and Cammarano [2015] performing thermodynamic modeling of various average chemical compositions proposed for the crust. The modeling, performed with the code PerpleX [Connolly, 2005], relies on the thermodynamic dataset from Holland and Powell [1998]. Compressional waves velocity and crustal layers thickness from the model CRUST 1.0 [Laske et al., 2013] offer additional constrains. The resulting lithospheric density models are tested against gravity (GOCE) data. Various crustal and mantle density models have been tested in order to ascertain the effects that uncertainties in the estimate of those features have on the modeled topography. We also test several viscosity models, either radially symmetric, the V1 profile from Mitrovica and Forte [2004], or more complex laterally varying structures. All the property fields are expanded in spherical harmonics, until degree 24, and implemented in the code StagYY [Tackley, 2008] to perform mantle instantaneous flow modeling and compute surface topography and gravitational field. Our results show the importance of constraining the crustal and mantle density structure relying on a multidisciplinary approach that involves experimentally robust thermodynamic datasets. Crustal density field has a strong effect on the isostatic component of topography. The models that we test, CRUST 1.0 and those in Guerri and Cammarano [2015], produce strong differences in the computed isostatic topography, in the range ±600 m. For the lithospheric mantle, relying on experimentally robust material properties constraints is necessary to infer a reliable density model that takes into account chemical heterogeneities. This approach is also fundamental to correctly interpret seismic models in temperature, a crucial parameter, necessary to determine the lithosphere-asthenosphere boundary, where static effects on topography leave place to dynamic ones. The comparison between results obtained with different viscosity fields, either radially symmetric or vertically and laterally varying, shows how lateral viscosity variations affect the results, in particular the modeled geoid, at different wavelengths. References: Brocher, T. M. (2005), Empirical Relations between Elastic Wavespeeds and Density in the Earth's Crust, Bulletin of the Seismological Society of America, 95(6), 2081-2092. Cammarano, F., P. J. Tackley, and L. Boschi (2011), Seismic, petrological and geodynamical constraints on thermal and compositional structure of the upper mantle: global thermochemical models, Geophys. J. Int. Connolly, J. A. D. (2005), Computation of phase equilibria by linear programming: A tool for geodynamic modeling and its application to subduction zone decarbonation, Earth and Planetary Science Letters (236), 524-541. Guerri, M., and F. Cammarano (2015), On the effects of chemical composition, water and temperature on physical properties of the Earth's continental crust, submitted to Geochemistry, Geophysics, Geosystem. Holland, T. J. B., and R. Powell (1998), An internally consistent thermodynamic data set for phases of petrological interest, J. metamorphic Geol., 16(309-343). Laske, G., G. Masters, Z. Ma, and M. E. Pasyanos (2013), CRUST1.0: An updated global model of Earth's crust, in EGU General Assembly 2013, edited, Geophysical Research Abstracts, Vienna. Mitrovica, J. X., and A. M. Forte (2004), A new inference of mantle viscosity based upon joint inversion of convection and glacial isostatic adjustment data, Earth and Planetary Science Letters, 225, 177-189. Tackley, P. J. (2008), Modelling compressible mantle convection with large viscosity contrasts in a three-dimensional spherical shell using the yin-yang grid, Phys. Earth Planet. Int.

  14. EAARL Submarine Topography - Northern Florida Keys Reef Tract

    USGS Publications Warehouse

    Brock, John C.; Wright, C. Wayne; Nayegandhi, Amar; Patterson, Matt; Travers, Laurinda J.; Wilson, Iris

    2007-01-01

    This Web site contains 32 Lidar-derived bare earth topography maps and GIS files for the Northern Florida Keys Reef Tract. These lidar-derived submarine topographic maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, 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.

  15. Sentinel-3 Surface Topography Mission (STM) User Data Products

    NASA Astrophysics Data System (ADS)

    Nogueira Loddo, Carolina; Scharroo, Remko; Wilson, Hilary; Bonekamp, Hans

    2015-04-01

    The Sentinel-3 Surface Topography Mission (STM) is a key component of the Copernicus Sentinel-3 mission, set to revolutionise operational oceanography with a suite of advanced surface topography data products over ocean and sea sea-ice. In addition the STM will collect data over all earth surfaces providing improved monitoring of River and Lake stage heights and inputs to the development of Digital Elevation Models. Sentinel-3 will be the first Earth Observation mission to provide 100% SAR altimetry coverage and LRM will be maintained as a backup operating mode. In order to fully exploit the SAR capability, and validating the algorithms evolution, lower level data products (L1A, L1B and L1B-S) will be made available to the users, in addition to the level 2 products. This poster provides an overview of the S-3 STM data products that will be generated operationally within the Sentinel-3 Payload Data Ground Segment by the Instrument Processing Facilities (IPFs), and disseminated to the users.

  16. Continuum Statistics of the Bed Topography in a Sandy River

    NASA Astrophysics Data System (ADS)

    McElroy, B.; Jerolmack, D.; Mohrig, D.

    2005-12-01

    Temporal and spatial variabilities in the bed geometry of sandy rivers contain information about processes of sediment transport that has not been fully appreciated. This is primarily due to a disparity between the dynamic nature of the sediment-fluid interface and the relatively static methods of surveying bed elevation, e.g. single profiles or point measurements. High resolution topographic data is paramount to understanding the dynamic behavior of sandy beds. We present and analyze a data set collected on a 2cm x 2cm grid at 1 minute intervals and with a vertical precision of ~1mm. This was accomplished by using Lambert-Beer's Law for attenuation of light to transform low-altitude aerial photographs into digital elevation models. Forty successive models were generated for a 20 m by 30 m section of channel bottom of the N. Loup River, Nebraska. To calculate the average, whole bed translation rate, or celerity, cross-correlations between a reference bed topography and its proceeding configurations were determined. Time differences between models were related to the shift lengths that produced correlation maxima for each model pair. The result is a celerity of ~3.8cm/s with a correlation coefficient of 0.992. Bed topography also deforms while it translates, and this can be seen as a secular decrease of correlation maxima. The form of this decrease in correlation is exponential, and from it an interface half-life is defined. In this case, the bed had become extensively reorganized within ~40 minutes, the time necessary to translate the bed one wavelength of the dominant roughness element. Although the bed is continuously deforming, its roughness is statistically stationary. Essentially, a mean roughness is maintained as the bed creates new realizations of itself. The dynamic nature of the whole bed and similarly transient behavior of individual elements suggests the utility of a holistic approach to studying the feedback between bed topography, fluid flow, and sediment transport. Furthermore, it raises questions about the usefulness of detailed analysis of flow and transport over individual forms.

  17. Mapping the Topography of Europa: The Galileo-Clipper Story

    NASA Astrophysics Data System (ADS)

    Schenk, Paul M.

    2014-11-01

    The renewed effort to return to Europa for global mapping and landing site selection raises the question: What do we know about Europa topography and how do we know it? The question relates to geologic questions of feature formation, to the issue of ice shell thickness, mechanical strength, and internal activity, and to landing hazards. Our topographic data base for Europa is sparse indeed (no global map is possible), but we are not without hope. Two prime methods have been employed in our mapping program are stereo image and shape-from-shading (PC) slope analyses. On Europa, we are fortunate that many PC-DEM areas are also controlled by stereo-DEMs, mitigating the long-wavelength uncertainties in the PC data. Due to the Galileo antenna malfunction, mapping is limited to no more than 20% of the surface, far less than for any of the inner planets. Thirty-seven individual mapping sites have been identified, scattered across the globe, and all have now been mapped. Excellent stereo mapping is possible at all Sun angles, if resolution is below ~350 m. PC mapping is possible at Sun angles greater than ~60 degrees, if emission angles are less than ~40 degrees. The only extended contiguous areas of topographic mapping larger than 150 km across are the two narrow REGMAP mapping mosaics extending pole-to-pole along longitudes 85 and 240 W. These are PC-only and subject to long-wavelength uncertainties and errors, especially in the north/south where oblique imaging produces layover. Key findings include the mean slopes of individual terrain types (Schenk, 2009), topography across chaos (Schenk and Pappalardo, 2004), topography of craters and inferences for ice shell thickness (Schenk, 2002; Schenk and Turtle, 2009), among others. A key discovery, despite the limited data, is that Europan terrains rarely have topographic amplitude greater than 250 meters, but that regionally Europa has imprinted on it topographic amplitudes of +/- 1 km, in the form of raised plateaus and bowed-down arcuate troughs. Such amplitudes imply that the ice shell is capable of supporting relief and is not extremely thin.

  18. Lunar Global Topography by Laser Altimeter (LALT) on board SELENE

    NASA Astrophysics Data System (ADS)

    Araki, H.; Tazawa, S.; Sasaki, S.; Noda, H.; Tsubokawa, T.; Asari, K.; Kawano, N.

    Japanese lunar orbiting mission SELENE (Selenological and Engineering Explorer) incorporates three selenodetic experiments by RISE group (Researches In SElenodesy) in National Astronomical Observatory of Japan. The first is Laser Altimeter (LALT) which measures the distance between the main orbiter and the lunar surface for the lunar topography. Second is four-way range-rate measurement by using a sub-satellite (RSAT) and the last is differential VLBI measurement of the two sub-satellites which are equipped with radio sources of S and X bands (VRAD). SELENE is scheduled to be launched in summer 2007 and various tests has been carried out. LALT incorporates Q-switched Nd:YAG laser system which transmits laser pulses per 1 second with 1064nm in wavelength, 17nsec time width, and 100mJ energy. Q-switch consists of LiNbO3 Pockels cell. The output beam divergence is 0.4 mrad after passing through the 7.3cm Galileo refractor. Beam spot size on lunar surface is typically 40m when main orbiter altitude is 100km. Range accuracy between SELENE orbiter and the lunar surface is 5m. The range data are transformed to the topography of the moon with the aid of position and attitude data of the SELENE orbiter. The foot print spacing will be about 1.6 km in the equatorial region after 1 yr mission period. In the pole regions the distance of ranged position on the moon will be less than 300m and the mean distance will be 100m. Mission objectives of LALT are summarized as making a low degree model of lunar figure and construction of lunar global topographic map with the accuracy that has never been so far. New topography of the moon will contribute the following scientific topics: [1] determination of the lunar global figure, [2] internal structure and surface processes, and [3] exploration of the lunar pole regions especially for permanent shadow or illuminated zones. The manufacture of flight model of LALT (LALT-FM) was finished in March 2003. LALT-FM joined the SELENE system integration test by March 2004 for checking mechanical and electrical interfaces with SELENE main orbiter as well as functional performance of LALT itself. PFM (Proto-Flight Model) integration test (PFT 1st half) was carried out successfully from May 2005 to Oct. 2005. LALT shall be in the middle of the PFT 2nd half or final environmental integration test scheduled from July 2006 to January 2007.

  19. EAARL coastal topography--Alligator Point, Louisiana, 2010

    USGS Publications Warehouse

    Nayegandhi, Amar; Bonisteel-Cormier, J.M.; Wright, C.W.; Brock, J.C.; Nagle, D.B.; Vivekanandan, Saisudha; Fredericks, Xan; Barras, J.A.

    2012-01-01

    This project provides highly detailed and accurate datasets of a portion of Alligator Point, Louisiana, acquired on March 5 and 6, 2010. 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 National Aeronautics and Space Administration (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 multispectral color-infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine aircraft, but the instrument was deployed on a Pilatus PC-6. 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 presurvey 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 used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the "bare earth" under vegetation from a point cloud of last return elevations.

  20. Eye shape and retinal topography in owls (Aves: Strigiformes).

    PubMed

    Lisney, Thomas J; Iwaniuk, Andrew N; Bandet, Mischa V; Wylie, Douglas R

    2012-01-01

    The eyes of vertebrates show adaptations to the visual environments in which they evolve. For example, eye shape is associated with activity pattern, while retinal topography is related to the symmetry or 'openness' of the habitat of a species. Although these relationships are well documented in many vertebrates including birds, the extent to which they hold true for species within the same avian order is not well understood. Owls (Strigiformes) represent an ideal group for the study of interspecific variation in the avian visual system because they are one of very few avian orders to contain species that vary in both activity pattern and habitat preference. Here, we examined interspecific variation in eye shape and retinal topography in nine species of owl. Eye shape (the ratio of corneal diameter to eye axial length) differed among species, with nocturnal species having relatively larger corneal diameters than diurnal species. All the owl species have an area of high retinal ganglion cell (RGC) density in the temporal retina and a visual streak of increased cell density extending across the central retina from temporal to nasal. However, the organization and degree of elongation of the visual streak varied considerably among species and this variation was quantified using H:V ratios. Species that live in open habitats and/or that are more diurnally active have well-defined, elongated visual streaks and high H:V ratios (3.88-2.33). In contrast, most nocturnal and/or forest-dwelling owls have a poorly defined visual streak, a more radially symmetrical arrangement of RGCs and lower H:V ratios (1.77-1.27). The results of a hierarchical cluster analysis indicate that the apparent interspecific variation is associated with activity pattern and habitat as opposed to the phylogenetic relationships among species. In seven species, the presence of a fovea was confirmed and it is suggested that all strigid owls may possess a fovea, whereas the tytonid barn owl (Tyto alba) does not. A size-frequency analysis of cell soma area indicates that a number of different RGC classes are represented in owls, including a population of large RGCs (cell soma area >150 m(2)) that resemble the giant RGCs reported in other vertebrates. In conclusion, eye shape and retinal topography in owls vary among species and this variation is associated with different activity patterns and habitat preferences, thereby supporting similar observations in other vertebrates. PMID:22722085

  1. Inferences About the Early Moon From Gravity and Topography

    NASA Technical Reports Server (NTRS)

    Smith, D. E.; Zuber, M. T.

    1998-01-01

    Recent spacecraft missions to the Moon have significantly improved our knowledge of the lunar gravity and topography fields, and have raised some new and old questions about the early lunar history. It has frequently been assumed that the shape of the Moon today reflects an earlier equilibrium state and that the Moon has retained some internal strength. Recent analysis indicating a superisostatic state of some lunar basins lends support to this hypothesis. On its simplest level, the present shape of the Moon is slightly flattened by 2.2 +/- 0.2 km while its gravity field, represented by an equipotential surface, is flattened only about 0.5 km. The hydrostatic component to the flattening arising from the Moon's present day rotation contributes only 7 m. This difference between the topographic shape of the MOon and the shape of its gravitational equipotential has frequently been explained as the "memory" of an earlier moon that was rotating faster and had a correspondingly larger hydrostatic flattening. To obtain this amount of hydrostatic flattening from rotation alone, and accounting for the contribution of the present-day gravity field, the Moon's rotation rate would need to be about 15x greater than at present, leading ot a period of < 2 days. Maintaining its synchronous rotation with Earth would require a radius for the Moon's orbit of approximately 9 Earth Radii. Unfortunately, our confidence in the observed lunar flattening is not as great as we would like. The uncertainty of .02 km may not properly reflect the limitations of the Clementine dataset, which did not sample poleward of latitudes 81 N and 79 S. Also, the large variation of topography +/- 8 km seen on the MOon dwarfs our estimate fo the flattening. Further the lunar south pole is on the edge of, or possibly inside the massive deep, South Pole-Aitken Basin. Thus, polar radii could be underestimated. This would yield a smaller flattening, which would imply a greater lunar rotation period and orbital radius. However, Basin compensation states and analyses of support and relaxation of topography at long wavelengths point to a lunar shape that has retained a flattening from an earlier faster rotation period.

  2. EAARL Coastal Topography - Northern Gulf of Mexico, 2007: First Surface

    USGS Publications Warehouse

    Smith, Kathryn E.L.; Nayegandhi, Amar; Wright, C. Wayne; Bonisteel, Jamie M.; Brock, John C.

    2009-01-01

    These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) elevation data 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), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. The project provides highly detailed and accurate datasets of select barrier islands and peninsular regions of Louisiana, Mississippi, Alabama, and Florida, acquired June 27-30, 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 presurvey 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 used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

  3. Analyses of Mars Topography, Gravity and Aroid: Implications for Tharsis and Hellas

    NASA Technical Reports Server (NTRS)

    Turcotte, D. L.; Shcherbakov, R.; Malamud, B. D.; Kucinskas, A. B.

    2001-01-01

    Correlations between topography, gravity, and aroid can provide important constraints on the structure and tectonic evolution of Mars. Additional information is contained in the original extended abstract.

  4. Ion-beam-induced topography and surface diffusion

    NASA Technical Reports Server (NTRS)

    Robinson, R. S.; Rossnagel, S. M.

    1982-01-01

    It is pointed out that the development of surface topography along with enhanced surface and bulk diffusion processes accompanying ion bombardment have generated growing interest among users of ion beams and plasmas for thin film or material processing. Interest in these processes stems both from attempts to generate topographic changes for specific studies or applications and from the need to suppress or control undesirable changes. The present investigation provides a summary of the current status of impurity-induced texturing, with emphasis on recent developments. Particular attention is given to the texturing accompanying deposition of an impurity material onto a solid surface while simultaneously etching the surface with an ion beam. A description of experimental considerations is provided, and a thermal-diffusion model is discussed along with the development of sputter cones, and aspects of impact-enhanced surface diffusion.

  5. SRTM Colored and Shaded Topography: Haro and Kas Hills, India

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On January 26, 2001, the Kachchh region in western India suffered the most deadly earthquake in India's history. This shaded topography view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake.

    The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an 'anticline,' which is an upwardly convex elongated fold of layered rocks. In this view, the anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the linear feature trending toward the southwest from the image center is an erosion-resistant 'dike,' which is an igneous intrusion into older 'host' rocks along a fault plane or other crack. These features are simple examples of how shaded topography can provide a direct input to geologic studies.

    In this image, colors show the elevation as measured by the Shuttle Radar Topography Mission (SRTM). Colors range from green at the lowest elevations, through yellow and red, to purple at the highest elevations. Elevations here range from near sea level to about 300 meters (about 1000 feet). Shading has been added, with illumination from the north (image top).

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise,Washington, DC.

    Size: 26.3 x 16.6 kilometers ( 16.3 x 10.3 miles) Location: 23.4 deg. North lat., 69.8 deg. East lon. Orientation: North toward the top Date Acquired: February 2000

  6. High-precision Ice Surface Topography Mapping Using Radar Interferometry

    NASA Astrophysics Data System (ADS)

    Moller, D.; Hensley, S.; Michel, T.; Rignot, E. J.; Simard, M.; Krabill, W. B.; Sonntag, J. G.

    2010-12-01

    In May 2009 a new radar technique for mapping ice surface topography was demonstrated in a Greenland campaign as part of the NASA International Polar Year activities. This was achieved with the airborne Glacier and Ice Surface Topography Interferometer (GLISTIN-A): a 35.6 GHz single-pass interferometer. Although the technique of using radar interferometry for mapping terrain has been demonstrated before, this is the first such application at millimeter-wave frequencies. Instrument performance indicates swath widths over the ice between 5-7km, with height precisions ranging from 30cm-3m at a posting of 3m x 3m. However, for this application the electromagnetic wave will penetrate an unknown amount into the snow cover thus producing an effective bias that must be calibrated. To evaluate this, GLISTIN-A flew a coordinated collection with the NASA Wallops Airborne Topographic Mapper (ATM) on a transect from Greenland’s Summit to its West coast. Two field calibration sites were established at Colorado Institute for Research in Environmental Science’s Swiss Camp and the National Science Foundation’s Summit station. Additional collections entailed flying a mosaic over Jakobshavn glacier which was repeated after 6 days to reveal surface dynamics. Through detailed calibration and inter-sensor comparisons we were able to observe penetration biases and compare them with theoretical expectations. We also demonstrated GLISTIN-A’s capability to measure the topography of large glacier systems in a seamless fashion and accurately measuring volume changes with a high level of spatial detail. In particular, repeating the airborne campaigns to observe elevation changes over time will allow very accurate volume change measurements. Not only is this very important for mass balance studies to have a precise mass-loss estimate, but the spatial pattern can reveal ice dynamics effects and surface mass balance effects. In this manner a high resolution, high-precision topographic mapping capability is an ideal complement to the ICESat, ICESat II and Cryosat altimeters. Interpolating between the high-accuracy elevation profiles from altimeters such as the ATM or ICESat II with the high-resolution GLISTIN-A swath will enable detailed ice-surface topography maps and extended spatial coverage. The result is the potential for higher fidelity mass-balance estimates and improved observational coverage. Upgrades are currently underway to improve the performance and portability of GLISTIN-A such that, onboard a long-range aircraft this radar can map Greenland’s significant glaciers in a few days. The upgraded GLISTIN-A will be compatible with GlobalHawk installation making, Antarctica basin and coastal mapping feasible. GLISTIN will make more topographic products available to glaciologists, initially through dedicated airborne campaigns or ultimately, perhaps, as a satellite mission.

  7. NCAR global model topography generation software for unstructured grids

    NASA Astrophysics Data System (ADS)

    Lauritzen, P. H.; Bacmeister, J. T.; Callaghan, P. F.; Taylor, M. A.

    2015-06-01

    It is the purpose of this paper to document the NCAR global model topography generation software for unstructured grids. Given a model grid, the software computes the fraction of the grid box covered by land, the gridbox mean elevation, and associated sub-grid scale variances commonly used for gravity wave and turbulent mountain stress parameterizations. The software supports regular latitude-longitude grids as well as unstructured grids; e.g. icosahedral, Voronoi, cubed-sphere and variable resolution grids. As an example application and in the spirit of documenting model development, exploratory simulations illustrating the impacts of topographic smoothing with the NCAR-DOE CESM (Community Earth System Model) CAM5.2-SE (Community Atmosphere Model version 5.2 - Spectral Elements dynamical core) are shown.

  8. Plate detachment, asthenosphere upwelling, and topography across subduction zones

    NASA Astrophysics Data System (ADS)

    Gvirtzman, Zohar; Nur, Amos

    1999-06-01

    This study analyzes the topography across subduction zones, considering the separate contributions of the crust and the mantle lithosphere to the observed surface elevation. We have found a transition from a region where the overriding plate is coupled to the descending slab and pulled down along with it to a region where the overriding plate floats freely on the asthenosphere. When the subducting slab retreats oceanward rapidly this transition is abrupt, and the edge of the overriding plate is uplifted. We propose that at some point during rapid slab rollback the overriding plate detaches and rebounds like a boat released from its keel. This event is associated with suction of asthenospheric material into the gap that is opened between the plates up to the base of the crust. As a result, the forearc uplifts, and magmatism in the arc increases.

  9. The Shuttle Radar Topography Mission arrives at KSC

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The vehicle carrying the Shuttle Radar Topography Mission (SRTM) arrives at the Multi-Payload Processing Facility. The primary payload on mission STS-99, the SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for September 1999. This radar system will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. Its objective is to obtain the most complete high-resolution digital topographic database of the Earth.

  10. Workers check out components of the Shuttle Radar Topography Mission

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In the Multi-Payload Processing Facility, Mary Reaves and Phil Smith, with the Jet Propulsion Laboratory, work on the carrier and horizontal antenna mast for the STS-99 Shuttle Radar Topography Mission (SRTM) while an unidentified worker watches. The SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during an 11-day mission in September 1999. This radar system will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. Its objective is to obtain the most complete high-resolution digital topographic database of the Earth.

  11. Workers check out components of the Shuttle Radar Topography Mission

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In the Multi-Payload Processing Facility, Beverly St. Ange, with the Jet Propulsion Laboratory, wires a biopod, a component of the STS-99 Shuttle Radar Topography Mission (SRTM). The SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during an 11-day mission in September 1999. This radar system will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. Its objective is to obtain the most complete high-resolution digital topographic database of the Earth.

  12. Workers check out components of the Shuttle Radar Topography Mission

    NASA Technical Reports Server (NTRS)

    1999-01-01

    In the Multi-Payload Processing Facility, Mary Reaves (left) and Phil Smith, with the Jet Propulsion Laboratory, check out the carrier and horizontal antenna mast for the STS-99 Shuttle Radar Topography Mission (SRTM). The SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during an 11-day mission in September 1999. This radar system will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. Its objective is to obtain the most complete high-resolution digital topographic database of the Earth.

  13. Geologic structure of shallow maria. [topography of lunar maria

    NASA Technical Reports Server (NTRS)

    Dehon, R. A.; Waskom, J. A.

    1975-01-01

    Isopach maps and structural contour maps of the eastern mare basins (30 deg N to 30 deg S; 0 deg to 100 deg E), constructed from measurements of partially buried craters, are presented and discussed. The data, which are sufficiently scattered to yield gross thickness variations, are restricted to shallow maria with less than 1500-2000 m of mare basalts. The average thickness of basalt in the irregular maria is between 200 and 400 m. Correlations between surface topography, basalt thickness, and basin floor structure are apparent in most of the basins that were studied. The mare surface is commonly depressed in regions of thick mare basalts; mare ridges are typically located in regions of pronounced thickness changes; and arcuate mare rilles are confined to thin mare basalts. Most surface structures are attributed to shallow stresses developed within the mare basalts during consolidation and volume reduction.

  14. Enceladus' internal ocean constrained from Cassini gravity and topography data

    NASA Astrophysics Data System (ADS)

    Lefevre, A.; Tobie, G.; Choblet, G.; Cadek, O.; Mitri, G.; Mass, M.; Behounkova, M.

    2015-10-01

    The intense activity at the south pole of Enceladus hints at an interna l water reservoir. The detection of sodium and potassium salts (about 1%) in icy grains emanating from Enceladus' south polar faults [1] indicates that the plume source is most likely connected to a salty subsurface ocean. The recent discovery of silicon-rich particles originating from Enceladus further indicates that hydrothermal interactions is currently occurring at the base of the ocean, and that hydrothermal products are quickly transferred to the plume source[2]. Based on topography and gravity data collected by the Cassini spacecraft[3, 4], this depth of ice/ocean interface is estimated to about 30-40 km underneath the South Pole. However the depth of ocean/rock interface as well as the extension of the ocean still remains unconstrained.

  15. Characterization of Mo/Si multilayer growth on stepped topographies

    SciTech Connect

    Boogaard, A. J. R. vcan den; Louis, E.; Zoethout, E.; Goldberg, K. A.; Bijkerk, F.

    2011-08-31

    Mo/Si multilayer mirrors with nanoscale bilayer thicknesses have been deposited on stepped substrate topographies, using various deposition angles. The multilayer morphology at the stepedge region was studied by cross section transmission electron microscopy. A transition from a continuous- to columnar layer morphology is observed near the step-edge, as a function of the local angle of incidence of the deposition flux. Taking into account the corresponding kinetics and anisotropy in layer growth, a continuum model has been developed to give a detailed description of the height profiles of the individual continuous layers. Complementary optical characterization of the multilayer system using a microscope operating in the extreme ultraviolet wavelength range, revealed that the influence of the step-edge on the planar multilayer structure is restricted to a region within 300 nm from the step-edge.

  16. Fractal structure of lunar topography: An interpretation of topographic characteristics

    NASA Astrophysics Data System (ADS)

    Cao, Wei; Cai, Zhanchuan; Tang, Zesheng

    2015-06-01

    Over the years, fractal geometry has been applied extensively in many fields of geoscience. Based on the global gridded data generated from the Lunar Reconnaissance Orbiter, we carry out our fractal measure to interpret lunar fractures by using qualitative (similar ratio) and quantitative (fractal dimension) approaches of fractal geometry. We find that most of the lunar surface exhibits fractal behavior over the given scales ranging from 1 to 256 m. Lunar maria have higher fractal dimensions than other geological units, while those of volcanic areas and highlands are lower than their surroundings. Simple and flat surfaces have low values of similar ratios and these areas indicate low surface roughness and young ages. Older-aged areas, such as the Hertzsprung basin, have low fractal dimensions and high similar ratios by their complicated topography.

  17. The evolution of Tharsis: Implications of gravity, topography, and tectonics

    NASA Technical Reports Server (NTRS)

    Banerdt, W. B.; Golombek, M. P.

    1990-01-01

    Dominating the Western Hemisphere of Mars, the Tharsis rise is an elongate area centered on Syria Planum that ascends as much as 8 to 10 km above the datum. It is intensely fractured by long, narrow grabens that extend radially hundreds of kilometers beyond the rise and is ringed by mostly concentric wrinkle ridges that formed over 2,000 km from the center of the rise. Its size, involving a full hemisphere of Mars, gives it a central role in the thermo-tectonic evolution of the planet and has stimulated a number of studies attempting to determine the sequence of events responsible for this feature. The constraints that gravity and topography data place on the current structure of Tharsis, along with insights into its development derived from comparisons of detailed regional mapping of faulting with theoretical deformation models are reviewed. Finally, a self-consistent model for the structure of Tharsis is proposed.

  18. The Shuttle Radar Topography Mission: A Global DEM

    NASA Technical Reports Server (NTRS)

    Farr, Tom G.; Kobrick, Mike

    2000-01-01

    Digital topographic data are critical for a variety of civilian, commercial, and military applications. Scientists use Digital Elevation Models (DEM) to map drainage patterns and ecosystems, and to monitor land surface changes over time. The mountain-building effects of tectonics and the climatic effects of erosion can also be modeled with DEW The data's military applications include mission planning and rehearsal, modeling and simulation. Commercial applications include determining locations for cellular phone towers, enhanced ground proximity warning systems for aircraft, and improved maps for backpackers. The Shuttle Radar Topography Mission (SRTM) (Fig. 1), is a cooperative project between NASA and the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense. The mission is designed to use a single-pass radar interferometer to produce a digital elevation model of the Earth's land surface between about 60 degrees north and south latitude. The DEM will have 30 m pixel spacing and about 15 m vertical errors.

  19. Forecasting hurricane impact on coastal topography: Hurricane Ike

    USGS Publications Warehouse

    Plant, Nathaniel G.; Stockdon, Hilary F.; Sallenger,, Asbury H., Jr.; Turco, Michael J.; East, Jeffery W.; Taylor, Arthur A.; Shaffer, Wilson A.

    2010-01-01

    Extreme storms can have a profound impact on coastal topography and thus on ecosystems and human-built structures within coastal regions. For instance, landfalls of several recent major hurricanes have caused significant changes to the U.S. coastline, particularly along the Gulf of Mexico. Some of these hurricanes (e.g., Ivan in 2004, Katrina and Rita in 2005, and Gustav and Ike in 2008) led to shoreline position changes of about 100 meters. Sand dunes, which protect the coast from waves and surge, eroded, losing several meters of elevation in the course of a single storm. Observations during these events raise the question of how storm-related changes affect the future vulnerability of a coast.

  20. Superoleophobic surfaces through control of sprayed-on stochastic topography.

    PubMed

    Campos, Raymond; Guenthner, Andrew J; Meuler, Adam J; Tuteja, Anish; Cohen, Robert E; McKinley, Gareth H; Haddad, Timothy S; Mabry, Joseph M

    2012-06-26

    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 analysis, electron microscopy, and image analysis for determination of fractal dimensionality. The coatings proved to be an especially useful class of liquid repellent materials due to their combination of simple and scalable deposition process, low surface energy, and the roughness characteristics of the aggregates. These characteristics interact in a unique way to prevent the buildup of binder in interstitial regions, preserving re-entrant curvature across multiple length scales, thereby enabling a wide range of liquid repellency, including superoleophobicity. In addition, rather than accumulating in the interstices, the binder becomes widely distributed across the surface of the aggregates, enabling a mechanism in which a simple shortage or excess of binder controls the extent of coating roughness at very small length scales, thereby controlling the extent of liquid repellence. PMID:22612380

  1. 2-Scale topography dry electrode for biopotential measurements.

    PubMed

    Vanlerberghe, F; De Volder, M; de Beeck, M Op; Penders, J; Reynaerts, D; Puers, R; Van Hoof, C

    2011-01-01

    The design and fabrication of a novel 2-scale topography dry electrode using macro and micro needles is presented. The macro needles enable biopotential measurements on hairy skin, the function of the micro needles is to decrease the electrode impedance even further by penetrating the outer skin layer. Also, a fast and reliable impedance characterization protocol is described. Based on this impedance measurement protocol, a comparison study is made between our dry electrode, 3 other commercial dry electrodes and a standard wet gel electrode. Promising results are already obtained with our electrodes which do not have skin piercing micro needles. For the proposed electrodes, three different conductive coatings (Ag/AgCl/Au) are compared. AgCl is found to be slightly better than Ag as coating material, while our Au coated electrodes have the highest impedance. PMID:22254700

  2. Mass and local topography measurements of Itokawa by Hayabusa.

    PubMed

    Abe, Shinsuke; Mukai, Tadashi; Hirata, Naru; Barnouin-Jha, Olivier S; Cheng, Andrew F; Demura, Hirohide; Gaskell, Robert W; Hashimoto, Tatsuaki; Hiraoka, Kensuke; Honda, Takayuki; Kubota, Takashi; Matsuoka, Masatoshi; Mizuno, Takahide; Nakamura, Ryosuke; Scheeres, Daniel J; Yoshikawa, Makoto

    2006-06-01

    The ranging instrument aboard the Hayabusa spacecraft measured the surface topography of asteroid 25143 Itokawa and its mass. A typical rough area is similar in roughness to debris located on the interior wall of a large crater on asteroid 433 Eros, which suggests a surface structure on Itokawa similar to crater ejecta on Eros. The mass of Itokawa was estimated as (3.58 +/- 0.18) x 10(10) kilograms, implying a bulk density of (1.95 +/- 0.14) grams per cubic centimeter for a volume of (1.84 +/- 0.09) x 10(7) cubic meters and a bulk porosity of approximately 40%, which is similar to that of angular sands, when assuming an LL (low iron chondritic) meteorite composition. Combined with surface observations, these data indicate that Itokawa is the first subkilometer-sized small asteroid showing a rubble-pile body rather than a solid monolithic asteroid. PMID:16741111

  3. Effect of surface topography upon micro-impact dynamics

    NASA Astrophysics Data System (ADS)

    Mohammadpour, M.; Morris, N. J.; Leighton, M.; Rahnejat, H.

    2016-03-01

    Often the effect of interactions at nano-scale determines the tribological performance of load bearing contacts. This is particularly the case for lightly loaded conjunctions where a plethora of short range kinetic interactions occur. It is also true of larger load bearing conjunctions where boundary interactions become dominant. At the diminutive scale of fairly smooth surface topography the cumulative discrete interactions give rise to the dominance of boundary effects rather than the bulk micro-scale phenomena, based on continuum mechanics. The integration of the manifold localized discrete interactions into a continuum is the pre-requisite to the understanding of characteristic boundary effects, which transcend the physical length scales and affect the key observed system attributes. These are energy efficiency and vibration refinement. This paper strives to present such an approach. It is shown that boundary and near boundary interactions can be adequately described by surface topographical measures, as well the thermodynamic conditions.

  4. Evolution of topography and material removal during nanoscale grinding

    NASA Astrophysics Data System (ADS)

    Eder, S. J.; Cihak-Bayr, U.; Vernes, A.; Betz, G.

    2015-11-01

    In this work we perform molecular dynamics simulations to quantify and parametrize the evolution of a bcc Fe work piece topography during nanometric grinding with multiple hard abrasive particles. The final surface quality depends on both the normal pressure and the abrasive geometry. We fit the time development of the substrates root mean squared roughness to an exponential function, allowing the definition of a run-in regime, during which the surface forgets about its initial state, and a steady-state regime where the roughness no longer changes. The time constants associated with smoothing and material removal are almost inversely proportional to each other, highlighting the distinctiveness of these two simultaneously occurring processes. We also describe an attempt to reduce the time required to achieve the smoothest possible surface finish by periodically re-adjusting the normal pressure during the grinding process.

  5. Recent and relict topography of Boo Bee patch reef, Belize

    USGS Publications Warehouse

    Halley, R.B.; Shinn, E.A.; Hudson, J.H.; Lidz, B.

    1977-01-01

    Five core borings were taken on and around Boo Bee Patch Reef to better understand the origin of such shelf lagoon reefs. The cores reveal 4 stages of development: (1) subaerial exposure of a Pleistocene "high" having about 8 meters of relief, possibly a Pleistocene patch reef; (2) deposition of peat and impermeable terrigenous clay 3 meters thick around the high; (3) initiation of carbonate sediment production by corals and algae on the remaining 5 meters of hard Pleistocene topography and carbonate mud on the surrounding terrigenous clay; and (4) accelerated organic accumulation on the patch reef. Estimates of patch reef sedimentation rates (1.6 m/1000 years) are 3 to 4 times greater than off-reef sedimentation rates (0.4-0.5 m/1000 years). During periods of Pleistocene sedimentation on the Belize shelf, lagoon patch reefs may have grown above one another, stacking up to form reef accumulation of considerable thickness.

  6. Learning From Philadelphia: Topographies of HIV/AIDS Media Assemblages.

    PubMed

    Cartwright, Lisa

    2016-03-01

    For this contribution to the special issue on "Mapping Queer Bioethics," the author employs an array of public health and popular media texts (especially Jonathan Demme's film Philadelphia) to challenge the construction and reconstruction of HIV-positive bodies as sites of bioethical concern. In outlining notions of "digital restoration," the author argues that there has been of late a remapping of the first decade of the HIV/AIDS pandemic through media projects assembled from archived materials. Accordingly, the author suggests that in the first decades of the 2000s, we have witnessed a media-archaeological turn, whereby old materials have been reassembled for commemorative purposes that oftentimes perform a reshaping of the topography of the first decade of the AIDS pandemic. PMID:26642876

  7. Different Approach to the Aluminium Oxide Topography Characterisation

    NASA Astrophysics Data System (ADS)

    Poljacek, Sanja Mahovic; Gojo, Miroslav; Raos, Pero; Stoic, Antun

    2007-04-01

    Different surface topographic techniques are being widely used for quantitative measurements of typical industrial aluminium oxide surfaces. In this research, specific surface of aluminium oxide layer on the offset printing plate has been investigated by using measuring methods which have previously not been used for characterisation of such surfaces. By using two contact instruments and non-contact laser profilometer (LPM) 2D and 3D roughness parameters have been defined. SEM micrographs of the samples were made. Results have shown that aluminium oxide surfaces with the same average roughness value (Ra) and mean roughness depth (Rz) typically used in the printing plate surface characterisation, have dramatically different surface topographies. According to the type of instrument specific roughness parameters should be used for defining the printing plate surfaces. New surface roughness parameters were defined in order to insure detailed characterisation of the printing plates in graphic reproduction process.

  8. Topography-Dependent Motion Compensation: Application to UAVSAR Data

    NASA Technical Reports Server (NTRS)

    Jones, Cathleen E.; Hensley, Scott; Michel, Thierry

    2009-01-01

    The UAVSAR L-band synthetic aperture radar system has been designed for repeat track interferometry in support of Earth science applications that require high-precision measurements of small surface deformations over timescales from hours to years. Conventional motion compensation algorithms, which are based upon assumptions of a narrow beam and flat terrain, yield unacceptably large errors in areas with even moderate topographic relief, i.e., in most areas of interest. This often limits the ability to achieve sub-centimeter surface change detection over significant portions of an acquired scene. To reduce this source of error in the interferometric phase, we have implemented an advanced motion compensation algorithm that corrects for the scene topography and radar beam width. Here we discuss the algorithm used, its implementation in the UAVSAR data processor, and the improvement in interferometric phase and correlation achieved in areas with significant topographic relief.

  9. New Orleans Topography, Radar Image with Colored Height

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for the animation

    About the animation: This simulated view of the potential effects of storm surge flooding on Lake Pontchartrain and the New Orleans area was generated with data from the Shuttle Radar Topography Mission. Although it is protected by levees and sea walls against storm surges of 18 to 20 feet, much of the city is below sea level, and flooding due to storm surges caused by major hurricanes is a concern. The animation shows regions that, if unprotected, would be inundated with water. The animation depicts flooding in one-meter increments.

    About the image: The city of New Orleans, situated on the southern shore of Lake Pontchartrain, is shown in this radar image from the Shuttle Radar Topography Mission (SRTM). In this image bright areas show regions of high radar reflectivity, such as from urban areas, and elevations have been coded in color using height data also from the SRTM mission. Dark green colors indicate low elevations, rising through yellow and tan, to white at the highest elevations.

    New Orleans is near the center of this scene, between the lake and the Mississippi River. The line spanning the lake is the Lake Pontchartrain Causeway, the world's longest overwater highway bridge. Major portions of the city of New Orleans are actually below sea level, and although it is protected by levees and sea walls that are designed to protect against storm surges of 18 to 20 feet, flooding during storm surges associated with major hurricanes is a significant concern.

    Data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter (approximately 200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Science Mission Directorate, Washington, D.C.

    Location: 30.2 degrees North latitude, 90.1 degrees East longitude Orientation: North toward the top, Mercator projection Size: 80.3 by 68.0 kilometers (49.9 by 42.3 miles) Image Data: Radar image and colored Shuttle Radar Topography Mission elevation model Date Acquired: February 2000

  10. SRF Cavity Surface Topography Characterization Using Replica Techniques

    SciTech Connect

    C. Xu, M.J. Kelley, C.E. Reece

    2012-07-01

    To better understand the roll of topography on SRF cavity performance, we seek to obtain detailed topographic information from the curved practical cavity surfaces. Replicas taken from a cavity interior surface provide internal surface molds for fine Atomic Force Microscopy (AFM) and stylus profilometry. In this study, we confirm the replica resolution both on surface local defects such as grain boundary and etching pits and compare the surface uniform roughness with the aid of Power Spectral Density (PSD) where we can statistically obtain roughness parameters at different scales. A series of sampling locations are at the same magnetic field chosen at the same latitude on a single cell cavity to confirm the uniformity. Another series of sampling locations at different magnetic field amplitudes are chosen for this replica on the same cavity for later power loss calculation. We also show that application of the replica followed by rinsing does not adversely affect the cavity performance.

  11. Intraoperative raster photogrammetry--the PAR Corneal Topography System.

    PubMed

    Belin, M W

    1993-01-01

    The PAR Corneal Topography System (CTS) is a computer-driven corneal imaging system that uses close-range raster photogrammetry to measure and produce a topographic map of the corneal surface. The CTS determines distortion in a projected two-dimensional grid. Unlike Placido-disc-based videokeratoscopes, the PAR CTS produces a true topographic map (elevation map) and requires neither a smooth reflective surface nor precise spatial alignment for accurate imaging. Because the system uses two noncoaxial optical paths, it can be integrated into other optical devices. A modified CTS was integrated into an experimental erbium: YAG photoablative laser. The CTS successfully imaged corneas before, after, and during laser photoablation. Its ability to image nonreflective surfaces and to be integrated into other optical systems may make it suitable for intraoperative refractive monitoring. PMID:8450443

  12. Enhanced surface hydrophobicity by coupling of surface polarity and topography

    PubMed Central

    Giovambattista, Nicolas; Debenedetti, Pablo G.; Rossky, Peter J.

    2009-01-01

    We use atomistic computer simulation to explore the relationship between mesoscopic (liquid drop contact angle) and microscopic (surface atomic polarity) characteristics for water in contact with a model solid surface based on the structure of silica. We vary both the magnitude and direction of the solid surface polarity at the atomic scale and characterize the response of an aqueous interface in terms of the solvent molecular organization and contact angle. We show that when the topography and polarity of the surface act in concert with the asymmetric charge distribution of water, the hydrophobicity varies substantially and, further, can be maximal for a surface with significant polarity. The results suggest that patterning of a surface on several length scales, from atomic to ?m lengths, can make important independent contributions to macroscopic hydrophobicity. PMID:19706474

  13. Modeling of SAR signatures of shallow water ocean topography

    NASA Technical Reports Server (NTRS)

    Shuchman, R. A.; Kozma, A.; Kasischke, E. S.; Lyzenga, D. R.

    1984-01-01

    A hydrodynamic/electromagnetic model was developed to explain and quantify the relationship between the SEASAT synthetic aperture radar (SAR) observed signatures and the bottom topography of the ocean in the English Channel region of the North Sea. The model uses environmental data and radar system parameters as inputs and predicts SAR-observed backscatter changes over topographic changes in the ocean floor. The model results compare favorably with the actual SEASAT SAR observed backscatter values. The developed model is valid for only relatively shallow water areas (i.e., less than 50 meters in depth) and suggests that for bottom features to be visible on SAR imagery, a moderate to high velocity current and a moderate wind must be present.

  14. Different Approach to the Aluminium Oxide Topography Characterisation

    SciTech Connect

    Poljacek, Sanja Mahovic; Gojo, Miroslav; Raos, Pero; Stoic, Antun

    2007-04-07

    Different surface topographic techniques are being widely used for quantitative measurements of typical industrial aluminium oxide surfaces. In this research, specific surface of aluminium oxide layer on the offset printing plate has been investigated by using measuring methods which have previously not been used for characterisation of such surfaces. By using two contact instruments and non-contact laser profilometer (LPM) 2D and 3D roughness parameters have been defined. SEM micrographs of the samples were made. Results have shown that aluminium oxide surfaces with the same average roughness value (Ra) and mean roughness depth (Rz) typically used in the printing plate surface characterisation, have dramatically different surface topographies. According to the type of instrument specific roughness parameters should be used for defining the printing plate surfaces. New surface roughness parameters were defined in order to insure detailed characterisation of the printing plates in graphic reproduction process.

  15. Imaging Surface Topography using Lloyd's Mirror in Photoemission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Jesson, D. E.; Pavlov, K. M.; Morgan, M. J.; Usher, B. F.

    2007-07-01

    We use Lloyd’s mirror to modulate electron photoemission in photoemission electron microscopy. This results in the projection of Lloyd’s fringes on to three-dimensional (3D) surface objects. An iterative reconstruction method is used to correct for distortions in the fringe pattern due to the cathode immersion lens, thereby providing a quantitative interpretation of surface shape. It is therefore possible to extract 3D height information directly from a two-dimensional, plan-view image. The technique is of sufficient intensity and contrast to study real-time changes in surface topography and we apply the method to study unusual contact-line dynamics during the reactive wetting of metal droplets.

  16. The Proposed Surface Water and Ocean Topography (SWOT) Mission

    NASA Technical Reports Server (NTRS)

    Fu, Lee-Lueng; Alsdorf, Douglas; Rodriguez, Ernesto; Morrow, Rosemary; Mognard, Nelly; Vaze, Parag; Lafon, Thierry

    2012-01-01

    A new space mission concept called Surface Water and Ocean Topography (SWOT) is being developed jointly by a collaborative effort of the international oceanographic and hydrological communities for making high-resolution measurement of the water elevation of both the ocean and land surface water to answer the questions about the oceanic submesoscale processes and the storage and discharge of land surface water. The key instrument payload would be a Ka-band radar interferometer capable of making high-resolution wide-swath altimetry measurement. This paper describes the proposed science objectives and requirements as well as the measurement approach of SWOT, which is baselined to be launched in 2019. SWOT would demonstrate this new approach to advancing both oceanography and land hydrology and set a standard for future altimetry missions.

  17. The American Geophysical Union Chapman Conference on Tectonics and Topography

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The Chapman Conference on Tectonics and Topography was held 31 Aug. - 4 Sep. 1992. The conference was designed to bring together disparate groups of earth scientists who increasingly found themselves working on similar problems but in relative isolation. Thus, process geomorphologists found themselves face-to-face with numerical modelers and field geomorphologists, hydrologists encountered geologists, and tectonophysicists found people with related data. The keynote speakers represented a wide variety of disciplines, all of which were relevant to the interdisciplinary theme of the conference. One of the most surprising issues that surfaced was the relative dearth of data that exists about erosion--process and rates. This was exacerbated by a reminder that erosion is critical to the evaluation of surface uplift.

  18. Thermally tailored gradient topography surface on elastomeric thin films.

    PubMed

    Roy, Sudeshna; Bhandaru, Nandini; Das, Ritopa; Harikrishnan, G; Mukherjee, Rabibrata

    2014-05-14

    We report a simple method for creating a nanopatterned surface with continuous variation in feature height on an elastomeric thin film. The technique is based on imprinting the surface of a film of thermo-curable elastomer (Sylgard 184), which has continuous variation in cross-linking density introduced by means of differential heating. This results in variation of viscoelasticity across the length of the surface and the film exhibits differential partial relaxation after imprinting with a flexible stamp and subjecting it to an externally applied stress for a transient duration. An intrinsic perfect negative replica of the stamp pattern is initially created over the entire film surface as long as the external force remains active. After the external force is withdrawn, there is partial relaxation of the applied stresses, which is manifested as reduction in amplitude of the imprinted features. Due to the spatial viscoelasticity gradient, the extent of stress relaxation induced feature height reduction varies across the length of the film (L), resulting in a surface with a gradient topography with progressively varying feature heights (hF). The steepness of the gradient can be controlled by varying the temperature gradient as well as the duration of precuring of the film prior to imprinting. The method has also been utilized for fabricating wettability gradient surfaces using a high aspect ratio biomimetic stamp. The use of a flexible stamp allows the technique to be extended for creating a gradient topography on nonplanar surfaces as well. We also show that the gradient surfaces with regular structures can be used in combinatorial studies related to pattern directed dewetting. PMID:24697617

  19. Nicotine intake and smoking topography in smokers with bipolar disorder

    PubMed Central

    Williams, Jill M; Gandhi, Kunal K; Lu, Shou-En; Steinberg, Marc L; Benowitz, Neal L

    2013-01-01

    Objectives Cigarette smoking behavior in bipolar disorder (BPD), including the effects of mood-stabilizing medications, has not been well characterized. Methods We compared serum nicotine, nicotine metabolite levels, and smoking topography in 75 smokers with BPD to 86 control smokers (CON). For some comparisons, an additional control group of 75 smokers with schizophrenia (SCZ) were included. Results There were no differences between the BPD and CON groups in baseline smoking characteristics or serum nicotine or cotinine levels. Fifty-one smokers with BPD (68.9%) were taking one of the following mood stabilizers: valproic acid, lamotrigine, carbamazepine, oxcarbazepine, lithium, or topiramate. The 3-hydroxycotinine-to-cotinine ratio, a marker of cytochrome P450 2A6 (CYP2A6) metabolic activity, was significantly higher in BPD versus CON and versus SCZ (0.68 versus 0.49 versus 0.54; p = 0.002). The difference between groups, however, was no longer significant when the analysis was repeated with those taking hepatic enzyme-inducing drugs (carbamazepine, oxcarbazepine, and topiramate) included as a covariate. The time between puffs, or interpuff interval (IPI), was shorter in BPD versus CON by an average of 3.0 sec (p < 0.05), although this was no longer significant when we removed smokers from the analysis of those taking hepatic enzyme inducers. Conclusions Smokers with BPD are not different from CON on most measures of nicotine intake and smoking topography. We found an increased rate of nicotine metabolism in smokers taking mood stabilizers that are hepatic enzyme inducers, including carbamazepine, oxcarbazepine, and topiramate. Smokers with rapid nicotine metabolism might be expected to smoke more intensely to compensate for the more rapid disappearance of nicotine from the blood and brain, and may have more difficulty in quitting smoking, although this requires further study. PMID:22938167

  20. Topography and geomorphology of the Huygens landing site on Titan

    USGS Publications Warehouse

    Soderblom, L.A.; Tomasko, M.G.; Archinal, B.A.; Becker, T.L.; Bushroe, M.W.; Cook, D.A.; Doose, L.R.; Galuszka, D.M.; Hare, T.M.; Howington-Kraus, E.; Karkoschka, E.; Kirk, R.L.; Lunine, J.I.; McFarlane, E.A.; Redding, B.L.; Rizk, B.; Rosiek, M.R.; See, C.; Smith, P.H.

    2007-01-01

    The Descent Imager/Spectral Radiometer (DISR) aboard the Huygens Probe took several hundred visible-light images with its three cameras on approach to the surface of Titan. Several sets of stereo image pairs were collected during the descent. The digital terrain models constructed from those images show rugged topography, in places approaching the angle of repose, adjacent to flatter darker plains. Brighter regions north of the landing site display two styles of drainage patterns: (1) bright highlands with rough topography and deeply incised branching dendritic drainage networks (up to fourth order) with dark-floored valleys that are suggestive of erosion by methane rainfall and (2) short, stubby low-order drainages that follow linear fault patterns forming canyon-like features suggestive of methane spring-sapping. The topographic data show that the bright highland terrains are extremely rugged; slopes of order of 30?? appear common. These systems drain into adjacent relatively flat, dark lowland terrains. A stereo model for part of the dark plains region to the east of the landing site suggests surface scour across this plain flowing from west to east leaving ???100-m-high bright ridges. Tectonic patterns are evident in (1) controlling the rectilinear, low-order, stubby drainages and (2) the "coastline" at the highland-lowland boundary with numerous straight and angular margins. In addition to flow from the highlands drainages, the lowland area shows evidence for more prolific flow parallel to the highland-lowland boundary leaving bright outliers resembling terrestrial sandbars. This implies major west to east floods across the plains where the probe landed with flow parallel to the highland-lowland boundary; the primary source of these flows is evidently not the dendritic channels in the bright highlands to the north. ?? 2007 Elsevier Ltd. All rights reserved.

  1. Bed topography and the development of forced bed surface patches

    NASA Astrophysics Data System (ADS)

    Nelson, Peter A.; Dietrich, William E.; Venditti, Jeremy G.

    2010-11-01

    Channel topography in gravel-bedded rivers interacts with the local flow and sediment transport fields to produce forced patches, which are temporally stable areas on the bed that display similar grain size and sorting. In an effort to enhance our empirical understanding of the mechanisms responsible for the formation of forced patches, we conducted a near-field scale flume experiment in which a large (55 m long, 2.74 m wide), straight, sediment recirculating flume was provided a constant water discharge and a unimodal sediment mixture ranging in size from 2 to 45 mm. A sequence of alternate bars developed and became essentially fixed in space, producing quasi-steady state bed topography over which we made measurements of local near-bed velocity and sediment transport. The bed developed temporally and spatially persistent forced patches with a general pattern of coarse bar tops and fine pools, which we characterized by visual mapping and with the application of an automated image processing procedure to a high-resolution (1 1 mm) digital elevation model of the bed surface. The boundary shear stress field, calculated from velocity measurements and with a quasi-three-dimensional hydraulic model (FaSTMECH), displayed substantial variability across the bar unit. Bed surface grain size did not correlate with local boundary shear stress; instead, topographically forced divergences in the boundary shear stress field were matched by divergences in the sediment transport field. The resultant cross-stream sediment flux was size-selective that in turn forced a bed surface textural response leading to coarse bar tops and fine pools. Our observations suggest that size-selective cross-stream bed load transport is a mechanism responsible for the development of forced bed surface patches in gravel bed channels that have topographically forced heterogeneous flow fields.

  2. Influence of topography on density of grassland passerines in pastures

    USGS Publications Warehouse

    Renfrew, R.B.; Ribic, C.A.

    2002-01-01

    Pastures provide substantial habitat for grassland birds of management concern in the Driftless Area of southwestern Wisconsin. The rolling topography in this region is characterized by lowland valleys surrounded by relatively steep and often wooded slopes which are set apart from more expansive treeless uplands. We hypothesized that there would be lower densities of area sensitive grassland passerines in lowland grasslands compared to upland grasslands because of their preference for larger more open grasslands. To test this hypothesis and assess how well pasture area and vegetation structure predicted grassland passerine density compared to upland/lowland status, we conducted point counts of birds in 60 pastures in May-June 1997 and 1998. Upland pastures generally supported greater densities of grassland passerines than lowland pastures. Densities of Savannah sparrow (Passerculus sandwichensis) and bobolink (Dolichonyx oryzivorus) were significantly higher in upland pastures than in lowland pastures. Grasshopper sparrow (Ammodramus savannarum) density was significantly higher on uplands in one of the study years. The density of eastern meadowlark (Sturnella magna), western meadowlark (S. neglecta) and sedge wren (Cistothorus platensis) did not differ significandy between uplands and lowlands. Grassland passerine density was also predicted by pasture size and vegetation structure. Densities of bobolink and grasshopper sparrow were higher in larger pastures. Bobolink and Savannah sparrow occurred on pastures with greater vegetation height-density and less bare ground; bobolink also preferred shallower litter depths. Lowland pastures supported grassland bird species of management concern and should not be neglected. However, we recommend that pasture management for grassland passerines in areas of variable topography favor relatively large upland pastures that will contain higher densities of species of management concern.

  3. Relations between heat flow, topography and Moho depth for Europe

    NASA Astrophysics Data System (ADS)

    Polkowski, Marcin; Majorowicz, Jacek; Grad, Marek

    2013-04-01

    The relation between heat flow, topography and Moho depth for recent maps of Europe is presented. New heat flow map of Europe (Majorowicz and Wybraniec, 2010) is based on updated database of uncorrected heat flow values to which paleoclimatic correction is applied across the continental Europe. Correction is depth dependent due to a diffusive thermal transfer of the surface temperature forcing of which glacial-interglacial history has the largest impact. This explains some very low uncorrected heat flow values 20-30 mW/m2 in the shields, shallow basin areas of the cratons, and in other areas including orogenic belts were heat flow was likely underestimated. New integrated map of the European Moho depth (Grad et al., 2009) is the first high resolution digital map for European plate understand as an area from Ural Mountains in the east to mid-Atlantic ridge in the west, and Mediterranean Sea in the south to Spitsbergen and Barents Sea in Arctic in the north. For correlation we used: onshore heat flow density data with palaeoclimatic correction (5318 locations), topography map (30 x 30 arc seconds; Danielson and Gesch, 2011) and Moho map (longitude, latitude and Moho depth, each 0.1 degree). Analysis was done in areas where data from all three datasets were available. Continental Europe area could be divided into two large domains related with Precambrian East European craton and Palaeozoic Platform. Next two smaller areas correspond to Scandinavian Caledonides and Anatolia. Presented results show different correlations between Moho depth, elevation and heat flow for all discussed regions. For each region more detailed analysis of these relation in different elevation ranges is presented. In general it is observed that Moho depth is more significant to HF then elevation. Depending on region and elevation range HF value in mW/m2 is up to two times larger than Moho depth in km, while HF relation to elevation varies much more.

  4. The Signature of Life in Stabilized Dune Topography

    NASA Astrophysics Data System (ADS)

    Barchyn, T. E.; Hugenholtz, C.

    2012-12-01

    Life dramatically affects aeolian dunes on Earth by modifying dune morphology and immobilizing sediment. Complete immobilization (stabilization) occurs when vegetation growth shelters the surface and eliminates sediment transport (and the capacity of the dune to clear vegetation). In unidirectional dune forms stabilization is usually preceded by a period of transition dominated by pronounced morphological change (e.g., parabolic dunes). Here, we hypothesize that stabilized topography holds previously unidentified clues detailing the kinematics and behavior of vegetation during stabilization (a 'signature'). During stabilization dune ridges advance downwind and 'bulldoze' vegetation in their path. We split dune ridges into a series of wind-parallel 'dune slices' and outline how slipface vegetation could prove to be a 'tipping point' in stabilization for each dune slice. Slipface vegetation sets off a self-reinforcing stabilization feedback, simplifying our treatment and yielding two predictable behaviors: slipfaces either clear vegetation (deposition rate > vegetation deposition tolerance), or succumb to vegetation and become immobilized (deposition rate < vegetation deposition tolerance). We model slipface deposition rates through slipface geometry and show how predictable variations in classical dune forms (i) could be responsible for incipient transformation of barchan to parabolic dunes, (ii) result in a progressive stabilization feedback fundamentally inconsistent with widely used dune activity indices, and (iii) record a quantitative signature of the relative kinematics of sediment flux and vegetation growth in stabilized slipface geometries. To explore the idea in real dune fields, we extract slipface deposition rates through slipface geometry recorded in digital terrain data for three dune fields: (i) Bigstick Sand Hills, SK, Canada, (ii) White Sands, NM, USA, and (iii) Cape Cod, MA, USA. With independent estimates of sediment flux and vegetation deposition tolerance we show how all three dune fields show consistent results with characteristic deposition rates approximately 60% of vegetation deposition tolerance. These results open the possibility that a consistent and identifiable 'signature of life' could be coded into all stabilized dune topography worldwide.

  5. Pre-LGM Northern Hemisphere ice sheet topography

    NASA Astrophysics Data System (ADS)

    Kleman, J.; Fastook, J.; Ebert, K.; Nilsson, J.; Caballero, R.

    2013-10-01

    We here reconstruct the paleotopography of Northern Hemisphere ice sheets during the glacial maxima of marine isotope stages (MIS) 5b and 4.We employ a combined approach, blending geologically based reconstruction and numerical modeling, to arrive at probable ice sheet extents and topographies for each of these two time slices. For a physically based 3-D calculation based on geologically derived 2-D constraints, we use the University of Maine Ice Sheet Model (UMISM) to calculate ice sheet thickness and topography. The approach and ice sheet modeling strategy is designed to provide robust data sets of sufficient resolution for atmospheric circulation experiments for these previously elusive time periods. Two tunable parameters, a temperature scaling function applied to a spliced Vostok-GRIP record, and spatial adjustment of the climatic pole position, were employed iteratively to achieve a good fit to geological constraints where such were available. The model credibly reproduces the first-order pattern of size and location of geologically indicated ice sheets during marine isotope stages (MIS) 5b (86.2 kyr model age) and 4 (64 kyr model age). From the interglacial state of two north-south obstacles to atmospheric circulation (Rocky Mountains and Greenland), by MIS 5b the emergence of combined Quebec-central Arctic and Scandinavian-Barents-Kara ice sheets had increased the number of such highland obstacles to four. The number of major ice sheets remained constant through MIS 4, but the merging of the Cordilleran and the proto-Laurentide Ice Sheet produced a single continent-wide North American ice sheet at the LGM.

  6. Pre-LGM Northern Hemisphere paleo-ice sheet topography

    NASA Astrophysics Data System (ADS)

    Kleman, J.; Fastook, J.; Ebert, K.; Nilsson, J.; Caballero, R.

    2013-05-01

    We here reconstruct the paleotopgraphy of Northern Hemisphere ice sheets during the glacial maxima of marine isotope stages (MIS) 5b and 4. We employ two approaches, geologically based reconstruction and numerical modeling, in mutually supportive roles to arrive at probable ice sheet extents and topographies for each of these two time slices. For a physically based 3-D calculation based on geologically derived 2-D constraints, we use the University of Maine Ice Sheet Model (UMISM) to calculate ice-sheet thickness and topography. The approach and ice-sheet modeling strategy is designed to provide robust data sets of sufficient resolution for atmospheric circulation experiments for these previously elusive time periods. Two tunable parameters, a temperature scaling function applied to a spliced Vostok-GRIP record, and spatial adjustment of climatic pole position, were employed iteratively to achieve a good fit to geological constraints where such were available. The model credibly reproduces the first-order pattern of size and location of geologically indicated ice sheets during marine isotope stages (MIS) 5b (86.2 kyr model age) and 4 (64 kyr model age). From the interglacial state of two north-south obstacles to atmospheric circulation (Rocky Mountains and Greenland), by MIS 5b combined Quebec-Central Arctic and Scandinavian-Barents/Kara ice sheets had effectively increased the number of such highland obstacles to four. This number remained constant through MIS 4, but at the last glacial maximum (LGM) dropped to three, through the merging of the Cordilleran and the proto-Laurentide Ice Sheet to a single continent-wide North American ice sheet.

  7. Interpretation of Lunar Topography: Impact Cratering and Surface Roughness

    NASA Astrophysics Data System (ADS)

    Rosenburg, Margaret A.

    This work seeks to understand past and present surface conditions on the Moon using two different but complementary approaches: topographic analysis using high-resolution elevation data from recent spacecraft missions and forward modeling of the dominant agent of lunar surface modification, impact cratering. The first investigation focuses on global surface roughness of the Moon, using a variety of statistical parameters to explore slopes at different scales and their relation to competing geological processes. We find that highlands topography behaves as a nearly self-similar fractal system on scales of order 100 meters, and there is a distinct change in this behavior above and below approximately 1 km. Chapter 2 focuses this analysis on two localized regions: the lunar south pole, including Shackleton crater, and the large mare-filled basins on the nearside of the Moon. In particular, we find that differential slope, a statistical measure of roughness related to the curvature of a topographic profile, is extremely useful in distinguishing between geologic units. Chapter 3 introduces a numerical model that simulates a cratered terrain by emplacing features of characteristic shape geometrically, allowing for tracking of both the topography and surviving rim fragments over time. The power spectral density of cratered terrains is estimated numerically from model results and benchmarked against a 1-dimensional analytic model. The power spectral slope is observed to vary predictably with the size-frequency distribution of craters, as well as the crater shape. The final chapter employs the rim-tracking feature of the cratered terrain model to analyze the evolving size-frequency distribution of craters under different criteria for identifying "visible" craters from surviving rim fragments. A geometric bias exists that systematically over counts large or small craters, depending on the rim fraction required to count a given feature as either visible or erased.

  8. In need of combined topography and bathymetry DEM

    NASA Astrophysics Data System (ADS)

    Kisimoto, K.; Hilde, T.

    2003-04-01

    In many geoscience applications, digital elevation models (DEMs) are now more commonly used at different scales and greater resolution due to the great advancement in computer technology. Increasing the accuracy/resolution of the model and the coverage of the terrain (global model) has been the goal of users as mapping technology has improved and computers get faster and cheaper. The ETOPO5 (5 arc minutes spatial resolution land and seafloor model), initially developed in 1988 by Margo Edwards, then at Washington University, St. Louis, MO, has been the only global terrain model for a long time, and it is now being replaced by three new topographic and bathymetric DEMs, i.e.; the ETOPO2 (2 arc minutes spatial resolution land and seafloor model), the GTOPO30 land model with a spatial resolution of 30 arc seconds (c.a. 1km at equator) and the 'GEBCO 1-MINUTE GLOBAL BATHYMETRIC GRID' ocean floor model with a spatial resolution of 1 arc minute (c.a. 2 km at equator). These DEMs are products of projects through which compilation and reprocessing of existing and/or new datasets were made to meet user's new requirements. These ongoing efforts are valuable and support should be continued to refine and update these DEMs. On the other hand, a different approach to create a global bathymetric (seafloor) database exists. A method to estimate the seafloor topography from satellite altimetry combined with existing ships' conventional sounding data was devised and a beautiful global seafloor database created and made public by W.H. Smith and D.T. Sandwell in 1997. The big advantage of this database is the uniformity of coverage, i.e. there is no large area where depths are missing. It has a spatial resolution of 2 arc minute. Another important effort is found in making regional, not global, seafloor databases with much finer resolutions in many countries. The Japan Hydrographic Department has compiled and released a 500m-grid topography database around Japan, J-EGG500, in 1999. Although the coverage of this database is only a small portion of the Earth, the database has been highly appreciated in the academic community, and accepted in surprise by the general public when the database was displayed in 3D imagery to show its quality. This database could be rather smoothly combined with the finer land DEM of 250m spatial resolution (Japan250m.grd, K. Kisimoto, 2000). One of the most important applications of this combined DEM of topography and bathymetry is tsunami modeling. Understanding of the coastal environment, management and development of the coastal region are other fields in need of these data. There is, however, an important issue to consider when we create a combined DEM of topography and bathymetry in finer resolutions. The problem arises from the discrepancy of the standard datum planes or reference levels used for topographic leveling and bathymetric sounding. Land topography (altitude) is defined by leveling from the single reference point determined by average mean sea level, in other words, land height is measured from the geoid. On the other hand, depth charts are made based on depth measured from locally determined reference sea surface level, and this value of sea surface level is taken from the long term average of the lowest tidal height. So, to create a combined DEM of topography and bathymetry in very fine scale, we need to avoid this inconsistency between height and depth across the coastal region. Height and depth should be physically continuous relative to a single reference datum across the coast within such new high resolution DEMs. (N.B. Coast line is not equal to 'altitude-zero line' nor 'depth-zero line'. It is defined locally as the long term average of the highest tide level.) All of this said, we still need a lot of work on the ocean side. Global coverage with detailed bathymetric mapping is still poor. Seafloor imaging and other geophysical measurements/experiments should be organized and conducted internationally and interdisciplinary ways more than ever. We always need greater technological advancement

  9. Osteoclast resorption of thermal spray hydoxyapatite coatings is influenced by surface topography.

    PubMed

    Gross, Karlis A; Muller, Dirk; Lucas, Helen; Haynes, David R

    2012-05-01

    Coating characteristics such as composition, crystallite features and topography collectively impact the cell response. The influence from splats has not yet been assessed for hydroxyapatite (HAp) thermal spray coatings. The objective of this work is to (a) survey the topography on commercial implants, (b) ascertain topography formation from single splats, and (c) determine the osteoclast resorption pattern on a topographically refined coating compared to dentine. Coatings on dental implants, an orthopedic screw, a femoral stem and a knee implant were studied for reference. The effects of substrate pre-heat, roughness, spray distance and particle size on the coating roughness and topography were studied. Human-derived osteoclasts were placed on a coating with refined topography and compared to dentine, a polished coating and polished sintered HAp. A pre-heat of at least 200C on titanium was required to form rounded splats. The greatest influence on coating roughness and topography arose from particle size. A 2-fold increase in the mean particle size from 30 to 72 ?m produced a significant difference (P<0.001) in roughness from 4.8 and 9.7 ?m. A model is shown to illustrate topography formation, nanostructure evolution on single splats, and the topography as seen in commercial implants. Osteoclasts showed a clear preference for activity on coatings with refined topography. A one-way ANOVA test revealed a significantly greater pit depth (P=0.022) for dentine (14 ?m) compared to the as-sprayed and polished coating (5 ?m). Coatings with topography display a similar number of resorption pits with dentine, but a 10-fold greater number than polished coatings, emphasizing the importance of flattened droplet topography on implant surfaces. PMID:22307028

  10. Impacts of mean dynamic topography on a regional ocean assimilation system

    NASA Astrophysics Data System (ADS)

    Yan, C.; Zhu, J.; Tanajura, C. A. S.

    2015-10-01

    An ocean data assimilation system was developed for the Pacific-Indian oceans with the aim of assimilating altimetry data, sea surface temperature, and in situ measurements from Argo (Array for Real-time Geostrophic Oceanography), XBT (expendable bathythermographs), CTD (conductivity temperature depth), and TAO (Tropical Atmosphere Ocean). The altimetry data assimilation requires the addition of the mean dynamic topography to the altimetric sea level anomaly to match the model sea surface height. The mean dynamic topography is usually computed from the model long-term mean sea surface height, and is also available from gravimetric satellite data. In this study, the impact of different mean dynamic topographies on the sea level anomaly assimilation is examined. Results show that impacts of the mean dynamic topography cannot be neglected. The mean dynamic topography from the model long-term mean sea surface height without assimilating in situ observations results in worsened subsurface temperature and salinity estimates. Even if all available observations including in situ measurements, sea surface temperature measurements, and altimetry data are assimilated, the estimates are still not improved. This proves the significant impact of the MDT (mean dynamic topography) on the analysis system, as the other types of observations do not compensate for the shortcoming due to the altimetry data assimilation. The gravimeter-based mean dynamic topography results in a good estimate compared with that of the experiment without assimilation. The mean dynamic topography computed from the model long-term mean sea surface height after assimilating in situ observations presents better results.

  11. Effects of Topography on Ground Motion in Southern California and the Wasatch Front Regions

    NASA Astrophysics Data System (ADS)

    Bielak, J.; Restrepo, D. L.; Taborda, R.

    2014-12-01

    We examine the effect of realistic surficial topography by conducting a set of deterministic 3D ground motion numerical simulations in the Southern California, and the Wasatch Front regions. We incorporate the highly heterogeneous surficial topography of both regions by implementing a Virtual Topography scheme into Hercules, the octree-based finite-element earthquake simulator developed by the Quake Group at Carnegie Mellon University. We used 808040 km3 volumes to perform fmax = 5 Hz simulations subjected to rupture sources representative of large earthquakes. Each region was simulated using three different models: (i) realistic 3D velocity structure with realistic topography (CMP model); (ii) realistic 3D velocity structure without topography (SQD model); and (iii) homogeneous half space with realistic topography (HMG) model. Our results illustrate how realistic topography greatly modifies the ground response. In particular, they highlight the importance of the combined interaction between source-effects, source-directivity, focusing, soft-soil conditions, and the 3D topography. We provide quantitative evidence of this interaction by the inclusion of maps of topographic amplification factors between the CMP and the SQD models.

  12. The role of erosion by fish in shaping topography around Hudson submarine canyon.

    USGS Publications Warehouse

    Twichell, D.C.; Grimes, Craig B.; Jones, R. S.; Able, K.W.

    1985-01-01

    The close match of areas of rough topography and high tilefish populations, the active burrowing of the sea floor, and the clustered distribution of the burrows suggest that the hummocky topography in this area may be the result of continuous erosion by tilefish and associated crustaceans during the Holocene. -from Authors

  13. Functional analysis of aberrant behavior through measurement of separate response topographies.

    PubMed Central

    Derby, K M; Hagopian, L; Fisher, W W; Richman, D; Augustine, M; Fahs, A; Thompson, R

    2000-01-01

    Functional analysis results for multiple topographies of aberrant behavior were graphed in an aggregate fashion and then separately for 48 clients. The results indicated that multiple topographies of behavior may be maintained by different contingencies. These results indicate that graphing functional analysis data in an aggregate fashion and then separately may improve the accuracy of their interpretation. PMID:10738962

  14. Topography of Responses in Conditional Discrimination Influences Formation of Equivalence Classes

    ERIC Educational Resources Information Center

    Kato, Olivia M.; de Rose, Julio C.; Faleiros, Pedro B.

    2008-01-01

    The effects of response topography on stimulus class formation were studied in two experiments. In Experiment 1, 32 college students were assigned to 2 response topographies and 2 stimulus sets, in a 2 x 2 design. Students selected stimuli by either moving a mouse to lace an arrow-shaped cursor on the stimulus or pressing a key corresponding to…

  15. Topography of Responses in Conditional Discrimination Influences Formation of Equivalence Classes

    ERIC Educational Resources Information Center

    Kato, Olivia M.; de Rose, Julio C.; Faleiros, Pedro B.

    2008-01-01

    The effects of response topography on stimulus class formation were studied in two experiments. In Experiment 1, 32 college students were assigned to 2 response topographies and 2 stimulus sets, in a 2 x 2 design. Students selected stimuli by either moving a mouse to lace an arrow-shaped cursor on the stimulus or pressing a key corresponding to

  16. An inversion of geoid and topography for mantle and crustal structure on Mars

    NASA Technical Reports Server (NTRS)

    Kiefer, Walter; Bills, Bruce; Frey, Herb; Nerem, Steve; Roark, Jim; Zuber, Maria

    1993-01-01

    Mars has the largest amplitude geoid anomalies and surface topography known on the terrestrial planets. A number of prior studies have analyzed Martian gravity anomalies and topography in terms of isostasy and flexure of the crust and lithosphere. Other studies have emphasized the role of mantle convection in producing gravity anomalies and topography in some regions of Mars. Geoid and topography observations for simultaneous estimates of density anomalies in the crust and mantle of Mars are inverted. In performing this study, a recent degree 50 spherical harmonic expansion of the Martian gravity field (GMM-l) and a corresponding resolution expansion of the USGS Mars topography model are used. However, our analysis is restricted to harmonic degrees up to L equals 25, which are better determined than the higher harmonics. This provides a half-wavelength horizontal resolution of 425 km.

  17. Surface topography of cylindrical gear wheels after smoothing in abrasive mass, honing and shot peening

    NASA Astrophysics Data System (ADS)

    Michalski, J.; Pawlus, P.; ?elasko, W.

    2011-08-01

    The present paper presents the analysis of surface topography of gear teeth as the result of final machining processes. Teeth of multiple cylindrical gears shaped by grinding were smoothed in abrasive mass, honed or shot peened. The measurement of gears were made using coordinate measuring machine and 3D surface topography stylus instrument. The following deviations were studied; pitch deviation, total pitches deviations, variation of teeth thickness and deviation of gear radial run-out. Changes in teeth surface topography during machining process were determined. 3D surface topography parameters, surface directionality as well as areal autocorrelation and power spectral density functions were taken into consideration. As the results of the analysis, the best surface topography with regard to gear operational properties was recommended.

  18. Digital holographic microscope for measurement of high gradient deep topography object based on superresolution concept.

    PubMed

    Liżewski, Kamil; Kozacki, Tomasz; Kostencka, Julianna

    2013-06-01

    In this Letter, a novel concept based on superresolution technique that enables the measurement of high gradient and deep topography objects using digital holographic (DH) microscopy is introduced. The major problem of DH systems is limited NA that prohibits the metrological characterization of object features of high frequencies. The proposed technique has the ability to extend spatial frequency spectrum of the measured topography by applying multidirectional plane wave illumination, which is experimentally realized with a grating. The technique recovers sample topography from the set of object waves with different object spectra that are converted into a set of topographies by using an algorithm which takes into account refraction. Application of this novel approach is experimentally validated by characterization of high gradient topography objects with maximum angle of tangent 65°. PMID:23722775

  19. Ultrasound imaging measurement of submerged topography in the muddy water physical model

    NASA Astrophysics Data System (ADS)

    Xiao, Xiongwu; Guo, Bingxuan; Li, Deren; Zou, Xianjian; Zhang, Peng; liu, Jian-chen; Zang, Yu-fu

    2015-08-01

    The real-time, accurate measurement of submerged topography is vital for the analysis of riverbed erosion and deposition. This paper describes a novel method of measuring submerged topography in the B-scan image obtained using an ultrasound imaging device. Results show the distribution of gray values in the image has a process of mutation. This mutation process can be used to adaptively track the topographic lines between riverbed and water, based on the continuity of topography in the horizontal direction. The extracted topographic lines, of one pixel width, are processed by a wavelet filtering method. Compared with the actual topography, the measurement accuracy is within 1?mm. It is suitable for the real-time measurement and analysis of all current model topographies with the advantage of good self-adaptation. In particular, it is visible and intuitive for muddy water in the movable-bed model experiment.

  20. Modelling wetting and drying effects over complex topography

    NASA Astrophysics Data System (ADS)

    Tchamen, G. W.; Kahawita, R. A.

    1998-06-01

    The numerical simulation of free surface flows that alternately flood and dry out over complex topography is a formidable task. The model equation set generally used for this purpose is the two-dimensional (2D) shallow water wave model (SWWM). Simplified forms of this system such as the zero inertia model (ZIM) can accommodate specific situations like slowly evolving floods over gentle slopes. Classical numerical techniques, such as finite differences (FD) and finite elements (FE), have been used for their integration over the last 20-30 years. Most of these schemes experience some kind of instability and usually fail when some particular domain under specific flow conditions is treated. The numerical instability generally manifests itself in the form of an unphysical negative depth that subsequently causes a run-time error at the computation of the celerity and/or the friction slope. The origins of this behaviour are diverse and may be generally attributed to:1. The use of a scheme that is inappropriate for such complex flow conditions (mixed regimes).2. Improper treatment of a friction source term or a large local curvature in topography.3. Mishandling of a cell that is partially wet/dry.In this paper, a tentative attempt has been made to gain a better understanding of the genesis of the instabilities, their implications and the limits to the proposed solutions. Frequently, the enforcement of robustness is made at the expense of accuracy. The need for a positive scheme, that is, a scheme that always predicts positive depths when run within the constraints of some practical stability limits, is fundamental. It is shown here how a carefully chosen scheme (in this case, an adaptation of the solver to the SWWM) can preserve positive values of water depth under both explicit and implicit time integration, high velocities and complex topography that may include dry areas. However, the treatment of the source terms: friction, Coriolis and particularly the bathymetry, are also of prime importance and must not be overlooked. Linearization with a combination of switching between explicit-implicit integration can overcome the stiffness of the friction and Coriolis terms and provide stable numerical integration. The treatment of the bathymetry source term is much more delicate. For cells undergoing a transient wet-dry process, the imposition of zero velocity stabilizes most of the approximations. However, this artificial zero velocity condition can be the cause of considerable error, especially when fast moving fronts are involved. Besides these difficulties linked with the internal position of the front within a cell versus the limited resolution of a numerical grid, it appears that the second derivative that defines whether the bed is locally convex or concave is a key indicator for stability. A convex bottom may lead to unbounded solutions. It appears that this behaviour is not linked to the numerics (numerical scheme) but rather to the mathematical theory of the SWWM. These concerns about stability have taken precedence, until now, over the crucial and related question of accuracy, especially near a moving front, and how these possible inaccuracies at the leading edge may affect the solution at interior points within the domain.This paper presents an in depth, fully two-dimensional space analysis of the aforementioned problem that has not been addressed before. The purpose of the present communication is not to propose what could be viewed as a final solution, but rather to provide some key considerations that may reveal the ingredients and insight necessary for the development of accurate and robust solutions in the future.

  1. Effective Elastic Thickness of Planetary Lithospheres from Gravity and Topography

    NASA Astrophysics Data System (ADS)

    Audet, P.

    2014-12-01

    The effective elastic thickness (Te) of the lithosphere controls the flexural response to transverse loading and can be used in conjunction with rheological models to remotely estimate surface density and heat flux of terrestrial planets. In the vast majority of studies, Te estimation is carried out in a two-step process: (1) the joint spectra (admittance and/or coherency) of gravity anomalies (free air and/or Bouguer) and topography are calculated within finite-size windows, and (2) the spectra are inverted using a model for the loading of an infinite elastic plate or shell. In recent years, research in the spatio-spectral analysis of Cartesian grids and improvements in lithospheric loading models have allowed the mapping of Te on the Earth at unprecedented resolution. Nevertheless, the limitations imposed by working with Cartesian data and models are hampering further advances in terrestrial Te studies. The planetary community, on the other hand, has traditionally used spatio-spectral methods that work directly on the sphere, thereby avoiding the undesirable distortions and biases inherent in Cartesian studies. However, the models and methods developed for the Earth have never been applied to planetary data, therefore also limiting further advances in the mapping of planetary Te. Here we combine advances in both terrestrial and planetary studies to allow the mapping of Te of terrestrial planets using a spherical wavelet analysis of gravity and topography data. In particular, we invert the wavelet admittance and coherence, either separately or jointly, and using either Bouguer or free air gravity anomaly data. The method is applied to estimate Te on Earth's continents and our results show that Te varies between <10 km in young orogenic provinces to >100 km in continental cores, in agreement with rheological models based on temperature-dependent rheology. Results obtained from the joint inversion of admittance and coherency show that simple lithospheric loading models fail to capture the complexity of the data, with adverse effects on the estimated parameters. Finally, we extend the analysis to the Moon and other terrestrial planets and discuss limitations and future applications of the fully spherical techniques.

  2. Quantifying Characteristic Length Scales and Patterns in Topography

    NASA Astrophysics Data System (ADS)

    Schmiddunser, Matthias; Ehlers, Todd A.

    2014-05-01

    The geometry of mountain topography depends on climate, tectonic, and biologic processes that operate on different temporal and spatial scales. Quantitative measures of landscape geometry are of interest for a) identifying potential correlations with the different types of processes, and b) for comparing observed topography with calibrated landscape evolution models of different regions. Over the years, several of these geomorphic metrics have been developed and used. Most of these metrics are regional values, i.e. they are calculated over an area of specific extent. Usually a region's typical horizontal length scale, like the average ridge-to-valley-distance, is used for this. However, this value is often chosen arbitrarily from a visual assessment of the landscape. In this study we aim to develop a quantitative measure of landscape properties that identifies dominant trends in drainage spacing and orientation. This is done by taking into account variations in topographic relief on different wavelenghts. More specifically, we use an autocorrelation function that is evaluated for different directions, thereby identifying prevalent orientation of features. The area of interest is then subdivided into parts of the thus obtained size and the process repeated, so that higher order structures are revealed. The results not only provides a size for the area over which other geomorphic metrics can be calculated such as the mean slope or the hypsometric integral, but may also be used as an additional measure for the form of the landscape itself. The method is applied to three regions along the South American Pacific coastal areas between latitudes of 26S and 40S. The study areas have distinctly different climate and vegetation conditions, showing the effect of different landscape forms on the values obtained. Results indicate a systematic variation between the three investigated regions. In the northern drier part of the coast results indicate large variations in the obtained correlation lengths depending on orientation and distinct higher order features. This is in stark contrast to the southern most region where little variation in correlation length and only weak secondary structures can be seen.

  3. Reconstructing past plate motions with abyssal hill topography

    NASA Astrophysics Data System (ADS)

    Dahn, M. R.; Pockalny, R. A.; King, C.

    2013-12-01

    The seafloor spreading history of oceanic plates is primarily reconstructed by using a combination of dated seafloor magnetic anomalies and fracture zone trends to locate Euler poles and determine rotation rates. In some regions, these conventional measures of determining spreading history do not exist and alternative methods are required. Abyssal hills are elongate, topographic highs that are created at and form parallel to the ridge axis of spreading centers. Once formed, the abyssal hills are transported onto the ridge flank and provide a record of ridge axis orientation. We propose using the orientation of abyssal hill topography to supplement existing plate motion reconstruction methods and to serve as a stand-alone method for regions where conventional methods will not apply. Our new method uses high-resolution bathymetry grids created with multibeam data with grid-node spacing of 100-200 m, determined by regional water depths. The bathymetric grids are detrended to remove depth-age relationships and spatially filtered to remove anomalous regions where seafloor age is unknown. The detrended grids are then clipped to remove anomalously deep (e.g., fracture zones) or anomalously shallow topography (e.g., seamounts). Abyssal hill orientations are determined by calculating the modal frequencies of slope azimuth for pre-defined sub-regions (e.g., 50 km x 50 km) of these modified grids. The Euler Pole is then found by an iterative least-squares method from a grid of potential Euler Poles; first a coarse grid and then a fine grid are utilized to avoid local minima. At each potential Euler Pole, the sum of the differences between predicted and observed abyssal hill trends is squared and the minimum value identifies the location of the best-fit Euler Pole. Our method was applied to the well-mapped Cocos-Pacific plate boundary along the northern East Pacific Rise for the past 3 Ma and the poorly constrained Mid-Cretaceous seafloor (84 - 120 Ma) in the southwest Pacific Ocean. The results for the northern East Pacific Rise are very encouraging and our calculated Euler Poles are within 4 degrees of the NUVEL 1a and 2 degrees of the MORVEL global relative motion models. We also applied our method to the EMAG2 magnetic anomaly intensity grids with similar encouraging results; 17 degrees NUVEL 1a & 11 degrees MORVEL. The results for the southwest Pacific are still preliminary, but the method effectively identifies regions with similar abyssal hill trends and may be useful for more detailed tectonic reconstructions of the enigmatic region.

  4. Simulation of stratified flow over three-dimensional topography

    NASA Astrophysics Data System (ADS)

    Ding, Li

    2002-01-01

    Large eddy simulation is employed to study the stratified flow over three-dimensional topography. Incompressible, time-dependent, three-dimensional and filtered Navier-Stokes equations are solved using a finite-volume method. The subgrid scale flow motions are modeled by a dynamic mixed model. The LES code is applied to the simulation of linearly stratified flow over a bell-shaped hill. The performance of the LES code has been investigated by comparing its predictions with those from a towing tank experiment. The simulation results are in good agreement with the experimental results. The height of the dividing streamline which separates the flow over the hill from the flow around the hill can be estimated by Sheppard's formula only because the energy loss due to friction/turbulence is balanced by energy provided by the pressure field. Drazin's theory can be used to predict the flow field when F < 0.4 if there is no wake region in the flow. Lee waves caused by the perturbation of the topography follow the linear theory reasonably. The effects of hill geometry have been studied by varying steepness and width of the hill. The variation of the dividing-streamline height with hill geometry is the result of the change of the pressure field. Two wake structures have been found at the leeside of the hill when F < l. One has a constant wake width and the other is similar to the wake generated by the two-dimensional flow passing around cylindrical bodies with a cross section equivalent to that of the hill at each level. In the low Froude number case (F << 1), the wake structure is dominated by the latter structure due to strong stratification. In the high Froude number case (F 1), the tilting of baroclinically-generated vortices forms a pair of vertically-oriented vortices with an approximately constant wake width. A scalar is released upstream at different heights. The major diffusion occurs when the plume approaches the hill due to the increasing shear. The distortion of streamlines by the hill has a great impact on the diffusion of the scalar.

  5. Kinetic model of dusty atmosphere around cometary nucleus with topography

    NASA Astrophysics Data System (ADS)

    Skorov, Yu. V.; Keller, H. U.; Markelov, G. N.

    The key to the explanation of most phenomena associated with the 'activity' of comets is the proper understanding of processes taking place within a thin layer around the nucleus/cometary atmosphere interface. As a comet is heated by the Sun, the highly variable dusty atmosphere is formed due to sublimation of volatile components of the cometary nucleus and lifting of nonvolatile grains. We believe that a cometary nucleus can be described as a body of high porosity and low density. The solar radiation can penetrate to a substantial skin depth. Thus both energy absorption and sublimation in the uppermost porous layer have a volumetric character. Due to intermolecular collisions in the innermost coma, backflows are formed. Therefore the nucleus and the innermost coma of an active comet constitute an interacting physical system. Our thermophysical model consists of a main block where the nonlinear nonstationary heat-conduction equation is solved and of three auxiliary blocks where the following are modeled: the absorption of the solar radiation; the transport of products of sublimation in the nonisothermal near-surface layer; and the backward gas flows caused by intermolecular collisions in the inner coma. The kinetic model of the near surface coma is treated by the Direct Simulation Monte Carlo (DSMC) model of dust-gas flows. Most of the time a cometary atmosphere is in a transitional and free-molecular regime and the kinetic approach is required to obtain a reliable solution. A modern implementation of DSMC and fast computers allow us to compute the gas flow in the near continuum regime. If the dust to gas mass ratio is low we can use an iterative approach consisting of the initialization, the pure gas flow computation, and the main procedure that includes tracking of dust grains in the gas flow. Tracking and computation of the gas flow is repeated until the solution converges. In high resolution pictures of a nuclei obtained by spacecraft, surface topography is observed. Cometary nuclei show material inhomogeneity that also leads to significant variations of activity. Gas flows for realistic topography (e.g. flat-bottom circular craters and mesas) as well as "spotty" surfaces are modeled. We show that the structure of the innermost coma depends on the nucleus shape and observe such phenomena as shock waves and jets. We conclude that dust grains mitigate gas flow discontinuities and that shock waves are less visible. Apart from that, dust grains effect gas density distribution: gas is being pushed away from dust jets and leaks into regions with a deficit of dust grains.

  6. Applications of laser ranging to ocean, ice, and land topography

    NASA Astrophysics Data System (ADS)

    Degnan, John J.

    1991-09-01

    Satellite laser ranging (SLR) has been used for over two decades in the study of a variety of geophysical phenomena, including global tectonic plate motion, regional crustal deformation near plate boundaries, Earth''s gravity field, the orientation of its polar axis and rate of spin, lunar dynamics and general relativistic studies. The subcentimeter precision of the technique is now attracting the attention of a new community of scientists, notably those interested in high- resolution ocean, ice, and land topography. Over the next several years, the international SLR network will provide an essential link between the geocentric terrestrial reference frame (as presently defined by the international VLBI and SLR networks) and two new oceanographic satellites, ERS-1 and TOPEX-Poseidon, which will range to sea and ice surfaces using microwave altimeters. The combined SLR/altimetry data set will provide precise orbits, improved gravity models, and estimates of the marine geoid. The latter are necessary to infer the dynamic sea surface topography and will enable measurements of parameters important to an understanding of global change, such as mean sea level and ice sheet thickness. Laser tracking of oceanographic satellites from multiple sites as they overfly special calibration towers equipped with tide gauges will also provide periodic estimates of microwave altimeter bias. The few-centimeter precision orbits determined by the SLR network will be used as ''ground truth'' data in the intercomparison and performance evaluation of developmental space radio-navigation systems such as GPS (TOPEX/Poseidon) and PRARE (ERS-1). Future spaceborne two-color SLR instruments, such as NASA''s geoscience laser ranging system (GLRS), can monitor the tectonically-induced motions of tide gauges by bouncing laser pulses off of collocated retroreflectors. Similar systems can measure the barometric loading over the open ocean. When used as transmitters in spaceborne or airborne altimeters, the narrow beamwidths and short pulsewidths available from lasers can provide high spatial resolution (both horizontal and vertical) topographic data over land and ice in support of a diverse set of science applications.

  7. Augmented Lagrangian for shallow viscoplastic flow with topography

    NASA Astrophysics Data System (ADS)

    Ionescu, Ioan R.

    2013-06-01

    In this paper we have developed a robust numerical algorithm for the visco-plastic Saint-Venant model with topography. For the time discretization an implicit (backward) Euler scheme was used. To solve the resulting nonlinear equations, a four steps iterative algorithm was proposed. To handle the non-differentiability of the plastic terms an iterative decomposition-coordination formulation coupled with the augmented Lagrangian method was adopted. The proposed algorithm is consistent, i.e. if the convergence is achieved then the iterative solution satisfies the nonlinear system at each time iteration. The equations for the velocity field are discretized using the finite element method, while a discontinuous Galerkin method, with an upwind choice of the flux, is adopted for solving the hyperbolic equations that describe the evolution of the thickness. The algorithm permits to solve alternatively, at each iteration, the equations for the velocity field and for the thickness. The iterative decomposition coordination formulation coupled with the augmented Lagrangian method works very well and no instabilities are present. The proposed algorithm has a very good convergence rate, with the exception of large Reynolds numbers (Re?1000), not involved in the applications concerned by the shallow viscoplastic model. The discontinuous Galerkin technique assure the mass conservation of the shallow system. The model has the exact C-property for a plane bottom and an asymptotic C-property for a general topography. Some boundary value problems were selected to analyze the robustness of the numerical algorithm and the predictive capabilities of the mechanical model. The comparison with an exact rigid flow solution illustrates the accuracy of the numerical scheme in handling the non-differentiability of the plastic terms. The influence of the mesh and of the time step are investigated for the flow of a Bingham fluid in a talweg. The role of the material cohesion in stopping a viscoplastic avalanche on a talweg with barrier was analyzed. Finally, the capacities of the model to describe the flow of a Bingham fluid on a valley from the broken wall of a reservoir situated upstream were investigated.

  8. Topography on Titan : New Results on Large and Small Scales

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.; Cassini Radar Team

    2011-12-01

    Although topographic coverage of Titan is and will remain sparse, some significant results have been obtained from global, regional and local measurements, via stereo, radarclinometry (shape-from-shading), autostereo (deviation from an assumed symmetric shape due to the inclined incidence), altimetry and SARtopo (monopulse) techniques. The global ellipsoidal shape (Zebker et al., 2009) provides important geophysical constraints on the interior. Hypsometry (Lorenz et al., 2011) provides insight into the balance of constructional and erosive processes and the strength of the lithosphere. Some local observations to be summarized in the talk include the measurement of mountains, the quantification of slopes that divert dunes and that drive fluid flow in river networks, as well as depth measurement of several impact craters and the assessment of candidate cryovolcanic structures. A recent new observation is a long altimetry pass T77 along the equator at the western edge of Xanadu, acquired both to constrain Titan's global shape and to understand the surface slopes and properties that may maintain the striking contrast between the dune fields of Shangri-La and the rugged and radiometrically anomalous Xanadu region. T77 also featured a SAR observation of the Ksa impact structure (discovered in SAR on T17), allowing a stereo DEM to be constructed. A feature shared by Earth and Titan is the ephemeral topography of liquids on the surface. Titan's lakes and seas likely vary in depth on geological (Myr-Gyr) and astronomical (~10 kyr) timescales : the depth of Ontario Lacus has been observed to vary on a seasonal timescale (~1 m/yr). Periodic changes of the order of 0.2-5m may occur diurnally, forced by Saturn gravitational tides. Finally, waves may be generated, at least during the windy season (which for Titan's north may be just about to begin) which can be constrained by radar and optical scattering measurements. Looking to the future, a Phase A study of the Titan Mare Explorer (TiME) mission, to float in Ligeia Mare in 2023, raises the prospect of seabed topography measurement via an acoustic depth sounder (sonar).

  9. Discriminant analysis of functional optical topography for schizophrenia diagnosis

    NASA Astrophysics Data System (ADS)

    Chuang, Ching-Cheng; Nakagome, Kazuyuki; Pu, Shenghong; Lan, Tsuo-Hung; Lee, Chia-Yen; Sun, Chia-Wei

    2014-01-01

    Abnormal prefrontal function plays a central role in the cognition deficits of schizophrenic patients; however, the character of the relationship between discriminant analysis and prefrontal activation remains undetermined. Recently, evidence of low prefrontal cortex (PFC) activation in individuals with schizophrenia has also been found during verbal fluency tests (VFT) and other cognitive tests with several neuroimaging methods. The purpose of this study is to assess the hemodynamic changes of the PFC and discriminant analysis between schizophrenia patients and healthy controls during VFT task by utilizing functional optical topography. A total of 99 subjects including 53 schizophrenic patients and 46 age- and gender-matched healthy controls were studied. The results showed that the healthy group had larger activation in the right and left PFC than in the middle PFC. Besides, the schizophrenic group showed weaker task performance and lower activation in the whole PFC than the healthy group. The result of the discriminant analysis showed a significant difference with P value <0.001 in six channels (CH 23, 29, 31, 40, 42, 52) between the schizophrenic and healthy groups. Finally, 68.69% and 71.72% of subjects are correctly classified as being schizophrenic or healthy with all 52 channels and six significantly different channels, respectively. Our findings suggest that the left PFC can be a feature region for discriminant analysis of schizophrenic diagnosis.

  10. Automated object-based classification of topography from SRTM data

    PubMed Central

    Drăguţ, Lucian; Eisank, Clemens

    2012-01-01

    We introduce an object-based method to automatically classify topography from SRTM data. The new method relies on the concept of decomposing land-surface complexity into more homogeneous domains. An elevation layer is automatically segmented and classified at three scale levels that represent domains of complexity by using self-adaptive, data-driven techniques. For each domain, scales in the data are detected with the help of local variance and segmentation is performed at these appropriate scales. Objects resulting from segmentation are partitioned into sub-domains based on thresholds given by the mean values of elevation and standard deviation of elevation respectively. Results resemble reasonably patterns of existing global and regional classifications, displaying a level of detail close to manually drawn maps. Statistical evaluation indicates that most of classes satisfy the regionalization requirements of maximizing internal homogeneity while minimizing external homogeneity. Most objects have boundaries matching natural discontinuities at regional level. The method is simple and fully automated. The input data consist of only one layer, which does not need any pre-processing. Both segmentation and classification rely on only two parameters: elevation and standard deviation of elevation. The methodology is implemented as a customized process for the eCognition® software, available as online download. The results are embedded in a web application with functionalities of visualization and download. PMID:22485060

  11. Automated object-based classification of topography from SRTM data

    NASA Astrophysics Data System (ADS)

    Drăguţ, Lucian; Eisank, Clemens

    2012-03-01

    We introduce an object-based method to automatically classify topography from SRTM data. The new method relies on the concept of decomposing land-surface complexity into more homogeneous domains. An elevation layer is automatically segmented and classified at three scale levels that represent domains of complexity by using self-adaptive, data-driven techniques. For each domain, scales in the data are detected with the help of local variance and segmentation is performed at these appropriate scales. Objects resulting from segmentation are partitioned into sub-domains based on thresholds given by the mean values of elevation and standard deviation of elevation respectively. Results resemble reasonably patterns of existing global and regional classifications, displaying a level of detail close to manually drawn maps. Statistical evaluation indicates that most of classes satisfy the regionalization requirements of maximizing internal homogeneity while minimizing external homogeneity. Most objects have boundaries matching natural discontinuities at regional level. The method is simple and fully automated. The input data consist of only one layer, which does not need any pre-processing. Both segmentation and classification rely on only two parameters: elevation and standard deviation of elevation. The methodology is implemented as a customized process for the eCognition® software, available as online download. The results are embedded in a web application with functionalities of visualization and download.

  12. Crater Topography on Titan: Implications for Landscape Evolution

    NASA Technical Reports Server (NTRS)

    Neish, Catherine D.; Kirk, R.L.; Lorenz, R. D.; Bray, V. J.; Schenk, P.; Stiles, B. W.; Turtle, E.; Mitchell, K.; Hayes, A.

    2013-01-01

    We present a comprehensive review of available crater topography measurements for Saturn's moon Titan. In general, the depths of Titan's craters are within the range of depths observed for similarly sized fresh craters on Ganymede, but several hundreds of meters shallower than Ganymede's average depth vs. diameter trend. Depth-to-diameter ratios are between 0.0012 +/- 0.0003 (for the largest crater studied, Menrva, D approximately 425 km) and 0.017 +/- 0.004 (for the smallest crater studied, Ksa, D approximately 39 km). When we evaluate the Anderson-Darling goodness-of-fit parameter, we find that there is less than a 10% probability that Titan's craters have a current depth distribution that is consistent with the depth distribution of fresh craters on Ganymede. There is, however, a much higher probability that the relative depths are uniformly distributed between 0 (fresh) and 1 (completely infilled). This distribution is consistent with an infilling process that is relatively constant with time, such as aeolian deposition. Assuming that Ganymede represents a close 'airless' analogue to Titan, the difference in depths represents the first quantitative measure of the amount of modification that has shaped Titan's surface, the only body in the outer Solar System with extensive surface-atmosphere exchange.

  13. Crater topography on Titan: implications for landscape evolution

    USGS Publications Warehouse

    Neish, C.D.; Kirk, R.L.; Lorenz, R.D.; Bray, V.J.; Schenk, P.; Stiles, B.W.; Turtle, E.; Mitchell, Ken; Hayes, A.

    2013-01-01

    We present a comprehensive review of available crater topography measurements for Saturn’s moon Titan. In general, the depths of Titan’s craters are within the range of depths observed for similarly sized fresh craters on Ganymede, but several hundreds of meters shallower than Ganymede’s average depth vs. diameter trend. Depth-to-diameter ratios are between 0.0012 ± 0.0003 (for the largest crater studied, Menrva, D ~ 425 km) and 0.017 ± 0.004 (for the smallest crater studied, Ksa, D ~ 39 km). When we evaluate the Anderson–Darling goodness-of-fit parameter, we find that there is less than a 10% probability that Titan’s craters have a current depth distribution that is consistent with the depth distribution of fresh craters on Ganymede. There is, however, a much higher probability that the relative depths are uniformly distributed between 0 (fresh) and 1 (completely infilled). This distribution is consistent with an infilling process that is relatively constant with time, such as aeolian deposition. Assuming that Ganymede represents a close ‘airless’ analogue to Titan, the difference in depths represents the first quantitative measure of the amount of modification that has shaped Titan’s surface, the only body in the outer Solar System with extensive surface–atmosphere exchange.

  14. Moiré topography: characteristics and clinical application.

    PubMed

    Porto, Flávia; Gurgel, Jonas Lírio; Russomano, Thais; Farinatti, Paulo De Tarso Veras

    2010-07-01

    Since 1970, the Moiré phenomenon has been employed as a method of clinical diagnosis in topographical analyses of the human body. The objective of this study was to review the literature on the main characteristics of the Moiré phenomenon and its use as a topographical method for clinical applications, particularly those related to postural deviations. A systematic search for papers written in English between 1966 and 2010 was performed according to pre-established selection criteria and the selected studies underwent a content analysis. The results showed an evolution in the method of Moiré topography (MT), which reflect an increasing effort to improve the accuracy and precision of the method, as well as to facilitate the interpretation of topograms using specific software. The Shadow and Projection Moiré techniques have more frequently been used in comparison with other techniques. On the other hand, the methodological procedures of MT are apparently not well defined in the literature. Although MT was shown to be useful in the detection of spinal deformities, there is still a lack of research in clinical settings, especially in the elderly. For the most part, the studies involve the tracking of scoliosis in school age children. Japan appears to be the most advanced country in terms of the application of MT. PMID:20643549

  15. Dynamic scalp topography reveals neural signs just before performance errors

    PubMed Central

    Ora, Hiroki; Sekiguchi, Tatsuhiko; Miyake, Yoshihiro

    2015-01-01

    Performance errors may cause serious consequences. It has been reported that ongoing activity of the frontal control regions across trials associates with the occurrence of performance errors. However, neural mechanisms that cause performance errors remain largely unknown. In this study, we hypothesized that some neural functions required for correct outcomes are lacking just before performance errors, and to determine this lack of neural function we applied a spatiotemporal analysis to high-density electroencephalogram signals recorded during a visual discrimination task, a d2 test of attention. To our knowledge, this is the first report of a difference in the temporal development of scalp ERP between trials with error, and correct outcomes as seen by topography during the d2 test of attention. We observed differences in the signal potential in the frontal region and then the occipital region between reaction times matched with correct and error outcomes. Our observations suggest that lapses of top-down signals from frontal control regions cause performance errors just after the lapses. PMID:26289925

  16. STS-99 Shuttle Radar Topography Mission Stability and Control

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

    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.

  17. Shielded piezoresistive cantilever probes for nanoscale topography and electrical imaging

    NASA Astrophysics Data System (ADS)

    Yang, Yongliang; Ma, Eric Yue; Cui, Yong-Tao; Haemmerli, Alexandre; Lai, Keji; Kundhikanjana, Worasom; Harjee, Nahid; Pruitt, Beth L.; Kelly, Michael; Shen, Zhi-Xun

    2014-04-01

    This paper presents the design and fabrication of piezoresistive cantilever probes for microwave impedance microscopy (MIM) to enable simultaneous topographic and electrical imaging. Plasma enhanced chemical vapor deposited Si3N4 cantilevers with a shielded center conductor line and nanoscale conductive tip apex are batch fabricated on silicon-on-insulator wafers. Doped silicon piezoresistors are integrated at the root of the cantilevers to sense their deformation. The piezoresistive sensitivity is 2 nm for a bandwidth of 10 kHz, enabling topographical imaging with reasonable speed. The aluminum center conductor has a low resistance (less than 5 ?) and small capacitance (1.7 pF) to ground; these parameters are critical for high sensitivity MIM imaging. High quality piezoresistive topography and MIM images are simultaneously obtained with the fabricated probes at ambient and cryogenic temperatures. These new piezoresistive probes remarkably broaden the horizon of MIM for scientific applications by operating with an integrated feedback mechanism at low temperature and for photosensitive samples.

  18. Dynamic scalp topography reveals neural signs just before performance errors.

    PubMed

    Ora, Hiroki; Sekiguchi, Tatsuhiko; Miyake, Yoshihiro

    2015-01-01

    Performance errors may cause serious consequences. It has been reported that ongoing activity of the frontal control regions across trials associates with the occurrence of performance errors. However, neural mechanisms that cause performance errors remain largely unknown. In this study, we hypothesized that some neural functions required for correct outcomes are lacking just before performance errors, and to determine this lack of neural function we applied a spatiotemporal analysis to high-density electroencephalogram signals recorded during a visual discrimination task, a d2 test of attention. To our knowledge, this is the first report of a difference in the temporal development of scalp ERP between trials with error, and correct outcomes as seen by topography during the d2 test of attention. We observed differences in the signal potential in the frontal region and then the occipital region between reaction times matched with correct and error outcomes. Our observations suggest that lapses of top-down signals from frontal control regions cause performance errors just after the lapses. PMID:26289925

  19. A Revolution in Mars Topography and Gravity and Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Smith, David E.

    2002-01-01

    Since the arrival of the Mars Global Surveyor (MGS) at Mars in September 1997 and the subsequent beginning of observations of the planet there has been a constant stream of surprises and puzzling observations that have kept scientists looking at new 'out of the box' explanations. Observations of the shape and topography have shown a planet with one hemisphere, the southern, several kilometers higher than the north and a northern hemisphere that is so flat and smooth in places that it's difficult to imagine it was not once the bottom of an ocean. And yet the ocean idea presents some enormous difficulties. The measurements of gravity derived from the tracking of MGS have shown that several Mars volcanoes are enormous positive gravity anomalies much larger than we see on Earth and revealed small errors in the orbit of Mars and or Earth. And the magnetic field is found to be composed of a number of extremely large crustal anomalies; but as far as can be ascertained there is no main dipole field such as we have on Earth. Understanding these diverse observations and placing them in the sequence of the evolution of the planet will be a long, challenging but rewarding task.

  20. The Shuttle Radar Topography Mission is moved to a workstand

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Inside the Space Station Processing Facility, workers watch as an overhead crane is lowered for lifting the Shuttle Radar Topography Mission (SRTM) from the transporter it is resting on. The SRTM is being moved to a workstand. The primary payload on mission STS-99, the SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle.

  1. The Shuttle Radar Topography Mission is moved to a workstand

    NASA Technical Reports Server (NTRS)

    1999-01-01

    After being lifted off the transporter (lower right) in the Space Station Processing Facility, the Shuttle Radar Topography Mission (SRTM) moves across the floor toward a workstand. The SRTM, which is the primary payload on mission STS-99, consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle.

  2. The Shuttle Radar Topography Mission is moved to a workstand

    NASA Technical Reports Server (NTRS)

    1999-01-01

    The move of the Shuttle Radar Topography Mission (SRTM) is nearly complete as it is lowered onto the workstand in the Space Station Processing Facility. The SRTM, which is the primary payload on mission STS-99, consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle.

  3. The Shuttle Radar Topography Mission is moved to a workstand

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Inside the Space Station Processing Facility, workers at each end of a workstand watch as the Shuttle Radar Topography Mission (SRTM) begins its descent onto it. The SRTM, which is the primary payload on mission STS-99, consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle.

  4. The Shuttle Radar Topography Mission is moved to a workstand

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Inside the Space Station Processing Facility, the Shuttle Radar Topography Mission (SRTM) is maneuvered by an overhead crane toward a workstand below. The SRTM, which is the primary payload on mission STS-99, consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle.

  5. The Shuttle Radar Topography Mission is moved to a workstand

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Workers inside the Space Station Processing Facility keep watch as an overhead crane begins lifting the Shuttle Radar Topography Mission (SRTM) from the transporter below. The SRTM is being moved to a workstand. The primary payload on mission STS-99, the SRTM consists of a specially modified radar system that will fly onboard the Space Shuttle during the 11-day mission scheduled for launch in September 1999. The objective of this radar system is to obtain the most complete high-resolution digital topographic database of the Earth. It will gather data that will result in the most accurate and complete topographic map of the Earth's surface that has ever been assembled. SRTM is an international project spearheaded by the National Imagery and Mapping Agency and NASA, with participation of the German Aerospace Center DLR. SRTM will be making use of a technique called radar interferometry, wherein two radar images are taken from slightly different locations. Differences between these images allow for the calculation of surface elevation, or change. To get two radar images taken from different locations, the SRTM hardware will consist of one radar antenna in the shuttle payload bay and a second radar antenna attached to the end of a mast extended 60 meters (195 feet) out from the shuttle.

  6. Adaptive Topographies and Equilibrium Selection in an Evolutionary Game

    PubMed Central

    Osinga, Hinke M.; Marshall, James A. R.

    2015-01-01

    It has long been known in the field of population genetics that adaptive topographies, in which population equilibria maximise mean population fitness for a trait regardless of its genetic bases, do not exist. Whether one chooses to model selection acting on a single locus or multiple loci does matter. In evolutionary game theory, analysis of a simple and general game involving distinct roles for the two players has shown that whether strategies are modelled using a single ‘locus’ or one ‘locus’ for each role, the stable population equilibria are unchanged and correspond to the fitness-maximising evolutionary stable strategies of the game. This is curious given the aforementioned population genetical results on the importance of the genetic bases of traits. Here we present a dynamical systems analysis of the game with roles detailing how, while the stable equilibria in this game are unchanged by the number of ‘loci’ modelled, equilibrium selection may differ under the two modelling approaches. PMID:25706762

  7. Shuttle Radar Topography Mission - New Products in 2005

    USGS Publications Warehouse

    U.S. Geological Survey

    2007-01-01

    In February 2000, the Shuttle Radar Topography Mission (SRTM) successfully collected Interferometric C-Band Synthetic Aperture Radar data over 80 percent of the Earth's land surface, for most of the area between 60?N and 56?S latitude. NASA and the National Geospatial-Intelligence Agency (NGA), formerly known as the National Imagery and Mapping Agency (NIMA), co-sponsored the mission. NASA's Jet Propulsion Laboratory (JPL) performed preliminary processing of SRTM data and forwarded partially finished data directly to NGA for finishing by NGA contractors and subsequent monthly deliveries to the NGA Digital Products Data Warehouse (DPDW). All data products delivered by the contractors conform to NGA SRTM Data Products and NGA Digital Terrain Elevation Data? (DTED?) specifications. The DPDW ingests the SRTM data products, checks them for formatting errors, loads the public SRTM DTED? into the NGA data distribution system, and ships them to the U.S. Geological Survey (USGS) Center for Earth Resources Observation and Science (EROS). In addition to NGA's SRTM DTED? format, USGS EROS has reformatted the data into a non-proprietary, generic raster binary SRTM format that is readable by most remote sensing software packages. The SRTM format is also publicly available from USGS EROS.

  8. TOPOGRAPHY OF THE ORGANIC COMPONENTS IN MOTHER-OF-PEARL

    PubMed Central

    Grgoire, Charles

    1957-01-01

    1. The topography of the organic components (conchiolin) has been investigated on positive, postshadow-cast, formvar, and carbon replicas of mother-of-pearl from shells of a Cephalopod, of two Gastropods, and of six Pelecypods. All these shells are characterized by a true nacreous inner shell layer. 2. The material included normal shell surfaces, fragments of cleavage obtained by fracture, and surfaces polished tangentially and transversally to the inner surface of the shells. Replicas of these surfaces were prepared before and after etching of graded heaviness, induced by a chelating agent (sequestrene NA 2, titriplex III). Micrographs of the successive steps of the process of corrosion have been recorded. 3. Corrosion unmasked, on the nacreous surfaces, organic membranes or sheets, running as continuous formations in between adjacent mineral lamellae, and separating the individual crystals of aragonite which are aligned in rows and constitute each lamella. 4. The interlamellar sheets of material exhibit a reticulated structure, which is especially visible in preparations orientated tangentially to the lamellae and to the tabular surface of the aragonite crystals. The pattern of this lace-like structure, different in the various species studied, appeared in the same species as closely similar to that reported previously in leaflets of thoroughly decalcified mother-of-pearl, dissociated by ultrasonic waves. The present results support former conclusions with regard to the existence of taxonomic differences between Cephalopods, Gastropods, and Pelecypods in the morphological organization of the organic phase within mother-of-pearl. PMID:13475393

  9. Lithospheric structure of Venus from gravity and topography

    NASA Astrophysics Data System (ADS)

    Jimnez-Daz, Alberto; Ruiz, Javier; Kirby, Jon F.; Romeo, Ignacio; Tejero, Rosa; Capote, Ramn

    2015-11-01

    There are many fundamental and unanswered questions on the structure and evolution of the venusian lithosphere, which are key issues for understanding Venus in the context of the origin and evolution of the terrestrial planets. Here we investigate the lithospheric structure of Venus by calculating its crustal and effective elastic thicknesses (Tc and Te, respectively) from an analysis of gravity and topography, in order to improve our knowledge of the large scale and long-term mechanical behaviour of its lithosphere. We find that the venusian crust is usually 20-25 km thick with thicker crust under the highlands. Our effective elastic thickness values range between 14 km (corresponding to the minimum resolvable Te value) and 94 km, but are dominated by low to moderate values. Te variations deduced from our model could represent regional variations in the cooling history of the lithosphere and/or mantle processes with limited surface manifestation. The crustal plateaus are near-isostatically compensated, consistent with a thin elastic lithosphere, showing a thickened crust beneath them, whereas the lowlands exhibit higher Te values, maybe indicating a cooler lithosphere than that when the venusian highlands were emplaced. The large volcanic rises show a complex signature, with a broad range of Te and internal load fraction (F) values. Finally, our results also reveal a significant contribution of the upper mantle to the strength of the lithosphere in many regions.

  10. Renewable Interfaces: Surface Topography Actuation for Complex Biological Adhesion Control

    NASA Astrophysics Data System (ADS)

    Pocivavsek, Luka; Ye, Sangho; Cao, Kathleen; Lee, Ka Yee C.; Velankar, Sachin; Wagner, William

    2015-03-01

    Controlling adhesion at biological interfaces is a complex problem with great biomedical importance. We use dynamic wrinkling, generated with PDMS/UVO chemistry under different macroscopic strains (ɛij ~ 0 . 3), to create a mechanical interfacial term that frustrates particle adhesion. This device actuates surface topography between flat (zero surface confinement χij) and wrinkled surfaces (χij ~(A / λ) 2 , where A and λ are wrinkle amplitude and wavelength, respectively), with a maximum rate of 0.6 Hz. Un-actuated PDMS placed in contact with whole sheep blood shows near total surface coverage with adhered platelets over 90 min. Actuation showed a nearly 100-fold decrease in platelet adhesion. Interestingly, topographic actuation is four times as effective compared to flat surface actuation in controlling platelet adhesion. Our model explores the competition between surface tension terms (Uγ = γɛij) and interfacial elastic terms (Uχ =Eij (t .ɛij2 +t3 . (χij /λ2)) generated because of actuation and wrinkling, where Eij is platelet modulus and t is characteristic platelet length scale. The condition for de-adhesion is Uχ >Uγ .

  11. Cell response to hydroxyapatite surface topography modulated by sintering temperature.

    PubMed

    Mealy, Jacob; O'Kelly, Kevin

    2015-11-01

    Increased mesenchymal stem cell (MSC) activity on hydroxyapatite (HA) bone tissue engineering scaffolds will improve their viability in diffusion-based in vivo environments and is therefore highly desirable. This work focused on modulating the sintered HA surface topography with a view to increasing cell activity; this was achieved by varying the sintering temperature of the HA substrates. Cells were cultured on the substrates for periods of up to 19 days and displayed a huge variation in viability. MSC metabolic activity was measured using a resazurin sodium salt assay and revealed that surfaces sintered from 1250 to 1350C significantly outperformed their lower temperature counterparts from day one (p???0.05). Surfaces sintered at 1300C induced 57% more cell activity than the control at day 16. No significant activity was observed on surfaces sintered below 1200C. It is suggested that this is due to the granular morphology produced at these temperatures providing insufficient contact area for cell attachment. In addition, we propose the average surface wavelength as a more quantitative surface descriptor than those readily found in the literature. The wavelengths of the substrates presented here were highly correlated with cell activity (R(2) ?=?0.9019); with a wavelength of 2.675 m on the 1300C surface inducing the highest cell response. PMID:25903792

  12. Representing the influence of subgrid topography on hydrology

    SciTech Connect

    Leung, L.R.; Ghan, S.J.

    1993-10-01

    Estimates of the impact of global climate change on land surface hydrology require climate information on scales far smaller than those explicitly resolved by global climate models of today and the foreseeable future. To bridge the gap between what is required and what is resolved, we propose a subgrid-scale parameterization of the influence of topography on clouds, precipitation, and land surface hydrology. The parameterization represents subgrid variations in surface elevation in terms of discrete elevation classes. Separate cloud and surface processes are calculated for each elevation class. The simulated surface temperature, precipitation, snowpack, and soil moisture for each elevation class can then be distributed according to the spatial distribution of surface elevation within each grid cell. The scheme is being applied to the Pacific Northwest Laboratory`s climate version of the Penn State/NCAR Mesoscale Model. Validation is being addressed by driving the model with observed lateral boundary conditions for the Pacific Northwest and comparing with surface observations. Preliminary results from the simulation will be presented.

  13. Display of Magellan SAR and Topography Data in Google Earth

    NASA Astrophysics Data System (ADS)

    Beyer, R. A.; Mehnert, E.; Sandwell, D. T.; Kolb, E.; Austin Foulkes, J.; Schwehr, K.; Johnson, C. L.

    2012-12-01

    Much of our understanding of the geodynamics and geology of Venus has been derived from radar imagery and topography from the Magellan mission (NASA 1989-1994). These data were archived at the Planetary Data System (PDS) and are easily and freely available. Unfortunately, the Magellan Venus data are far less accessible than those of the Earth, Mars, and the Moon. Data for these bodies are available via the Google Earth geobrowser, allowing anyone to easily explore the latest imagery and surface information. In an effort to promote public interest in Venus, we have created content for Google Earth that displays three types of information from the Magellan-era. First the FMAP compilation of the Magellan SAR imagery has been assembled into a global overlay image for rapid panning and zooming. Second, the reprocessed altimetry data [Ford and Pettingell, 1992; Rappaport et al. 1999] have been carefully edited and merged with a global spherical harmonic analysis [Wieczorek, 2007] to form a 10-km resolution global DEM of the planet. Finally the IAU feature names along with the content from ``The Face of Venus'' [Roth and Wall, 1995] have been assembled as an overlay to provide basic naming and geology information. A draft version of this material is available by adding this Network Link in Google Earth: http://byss.arc.nasa.gov/ge-venus/venus.kml. We welcome comments and suggestions on how to best represent Venus data for the public

  14. Fractal analysis of surface topography in ground monocrystal sapphire

    NASA Astrophysics Data System (ADS)

    Wang, Qiuyan; Liang, Zhiqiang; Wang, Xibin; Zhao, Wenxiang; Wu, Yongbo; Zhou, Tianfeng

    2015-02-01

    The surface characterization of ground monocrystal sapphire is investigated by fractal analysis method. A serial of ground sapphire surfaces in ductile removal and brittle removal mode are obtained by grinding experiments, and their three dimensional (3D) and two dimensional (2D) fractal dimensions are calculated and analyzed by box-counting methods. The 3D surface fractal dimension Ds shows a negative correlation with the surface roughness parameter Ra and is sensitive to the ground surface defects. For the ground surface with larger fractal dimension Ds, its micro-topography is more exquisite with minor defects. Once the fractal dimension Ds become smaller, deep cracks and pronounced defects are exhibited in ground surface. Moreover, the material removal mode can be implied from the distribution of 2D cross-sectional profile fractal dimension DL. The workpiece surface generated in ductile removal mode has high surface quality with high 2D and 3D fractal dimensions. This study indicates that the box-counting fractal analysis is an effective method to evaluate ground sapphire surface comprehensively.

  15. New Products From the Shuttle Radar Topography Mission

    NASA Astrophysics Data System (ADS)

    Gesch, Dean; Farr, Tom; Slater, James; Muller, Jan-Peter; Cook, Sally

    2006-05-01

    New data products with broad applicability to the Earth sciences are now available from the Shuttle Radar Topography Mission (SRTM). SRTM, a joint project of the National Geospatial-Intelligence Agency (NGA) and NASA, flew aboard the Space Shuttle Endeavour on an 11 day mission in February 2000 with the goal of collecting a near-global data set of high-resolution elevation data [Farr and Kobrick, 2000]. Data from the mission have been available to researchers for several years, but newly available products offer enhanced usability and applicability. Final products include elevation data resulting from a substantial editing effort by the NGA in which water bodies and coastlines were well defined and data artifacts known as spikes and wells (single pixel errors) were removed. This second version of the SRTM data set, also referred to as `finished' data, represents a significant improvement over earlier versions that had nonflat water bodies, poorly defined coastlines, and numerous noise artifacts. The edited data are available at a one-arc-second resolution (approximately 30 meters) for the United States and its territories, and at a three-arc-second resolution (approximately 90 meters) for non-U.S. areas.

  16. Stroke topography and outcome in relation to hyperglycaemia and diabetes.

    PubMed Central

    Kiers, L; Davis, S M; Larkins, R; Hopper, J; Tress, B; Rossiter, S C; Carlin, J; Ratnaike, S

    1992-01-01

    In a prospective study to analyse stroke topography and outcome in diabetics and to determine the prognostic value of blood glucose and glycosylated haemoglobin estimation, we evaluated 176 patients with acute stroke. The patients were classified into four groups on the basis of history, fasting glucose, and glycosylated haemoglobin: euglycaemic patients with no history of diabetes, stress hyperglycaemia, newly diagnosed diabetics, and known diabetics. A high prevalence of undiagnosed diabetes was shown. No difference was found in the type or site of stroke between the four groups. No difference was found in the site of symptomatic or incidental lesions on computerised axial tomography. Patients with stress hyperglycaemia and known diabetics had more severe strokes. Mortality was higher in patients with stress hyperglycaemia, newly diagnosed diabetics, and the combined diabetes groups. This increased mortality was evident in the hyperglycaemic and diabetic groups, even after excluding patients with cerebral haemorrhage. Stroke severity and mortality also increased independently with blood glucose in the euglycaemic group. We conclude that there is a correlation between admission glucose concentration, diabetes, and poor stroke outcome, which may not be attributed to stroke type or location. PMID:1583510

  17. Topography and Vegetation Characterization using Dual-Wavelength Airborne Lidar

    NASA Astrophysics Data System (ADS)

    Neuenschwander, A. L.; Bradford, B.; Magruder, L. A.

    2014-12-01

    Monitoring Earth surface dynamics at an ever increasing resolution has helped to support the characterization of local topography, including vegetated and urban environments. Airborne remote sensing using light detection and ranging (LIDAR) is naturally suited to characterize vegetation and landscapes as it provides detailed three-dimensional spatial data with multiple elevation recordings for each laser pulse. The full waveform LIDAR receiver is unique in this aspect as it can capture and record the complete temporal history of the reflected signal, which contains detailed information about the structure of the objects and ground surfaces illuminated by the beam. This study examines the utility of co-collected, dual-wavelength, full waveform LIDAR data to characterize vegetation and landscapes through the extraction of waveform features, including total waveform energy, canopy energy distribution, and foliage penetration metrics. Assessments are performed using data collected in May 2014 over Monterey, CA, including the Naval Postgraduate School campus area as well as the Point Lobos State Natural Reserve situated on the Monterey coast. The surveys were performed with the Chiroptera dual-laser LIDAR mapping system from Airborne Hydrography AB (AHAB), which can collect both green (515nm) and near infrared (1064nm) waveforms simultaneously. Making use of the dual waveforms allows for detailed characterization of the vegetation and landscape not previously possible with airborne LIDAR.

  18. Numerical investigation of Rayleigh-wave propagation on topography surface

    NASA Astrophysics Data System (ADS)

    Wang, Limin; Luo, Yinhe; Xu, Yixian

    2012-11-01

    Rayleigh waves propagate along the free surface and vanish exponentially in the vertical direction, which suggests that they are strongly influenced by free-surface topography. Since they have strong energy, Rayleigh waves are the most damaging wave during earthquake, and have strong noise in petroleum exploration. Because of their strong energy and the dispersive characteristic in a vertically inhomogeneous earth, however, they are widely utilized in environmental and engineering geophysics. To study how Rayleigh-wave behaves with topographic free surface, we proposed a finite difference scheme incorporating the acoustic/elastic interface approach into a 'stair-case' mesh for modeling surface-wave propagation. The effectiveness and accuracy were demonstrated by modeling results of a two-dimensional homogeneous half-space model with a slope free surface. The characteristics of Rayleigh-wave propagation strongly affected by topographic free surface are demonstrated by numerical examples of three simple topographic models. The most important revealed by modeling results is that, the dispersion characteristics are determined by the thicknesses of the underground layers in the direction perpendicular to the slope free surface. The middle of receiver-spread assumption was further verified, which provides a guideline to applying surface-wave methods to near-surface problems.

  19. Dust as a potential tracer for the flow over topography

    NASA Astrophysics Data System (ADS)

    Alpert, Pinhas; Barkan, Yossi

    2015-04-01

    The distribution of mineral dust around topographical obstacles is examined, using the dimensionless Froude number (Fr) that describes different flow regimes in a fluid. Flow around a peak with a close-to-circular shape in dusty environment like the Sahara and the Sahel was examined in order to investigate the distribution of the dust around the obstacle in different flow regimes as expressed by the Fr number. The Total Ozone Mapping Spectrometer Aerosol Index (TOMS-AI) daily Aerosol Index, and the u and v wind components were used for the years 1979-1992, i.e. 14 years. It is first shown by the TOMS-AI data that the shape of the dust distribution around the circular peak is in good agreement with the shape of the peak itself. Additionally good correlation exists between the vertical distribution of the dust above the peak and the Froude Number in its vicinity. This method allows for the first time the investigation of flow above and around topographical obstacles in the open space employing dust as the flow-tracer. References: J. Barkan and P. Alpert, "Dust as a potential tracer for the flow over topography", Intern. J. Geosci., (in press) 2015. J. Barkan and P. Alpert, "A unique case-study of near-circular Saharan dust transport over the Atlantic Ocean", Atmospheric and Climate Sciences (ACS), 4, 164-170, 2014.

  20. Usefulness of surface topography analysis in psoriatic skin.

    PubMed

    Monti, M; Bozzetti, M; Motta, S; Barbareschi, M

    1989-01-01

    The study of skin reliefs attracted the attention of dermatologists because it may reflect development, assembly and functional activity of the stratum corneum--and therefore of the entire epidermis. Psoriasis is characterized by a deep alteration of surface texture: and this can be related to the severity of the disease. In this work we studied, by means of skin profilometry, the roughness parameters that better describe the distinctive features of psoriatic skin topography and the modification of psoriatic surface after topical therapy. For this purpose we analyzed psoriatic skin reliefs using silicone rubber replicas both before therapy and after coal-tar topical application. A statistically significant difference between uninvolved and psoriatic skin for Ra- but not for Rz- values was observed in replicas made before therapy. After therapy, replicas showed no significant difference either for Ra or for Rz values. The profilometric analysis of psoriatic skin can be considered a useful method to characterize psoriatic plaque and the improvement obtained by topical therapy. PMID:2609892

  1. Inferences About the Early Moon from Gravity and Topography

    NASA Technical Reports Server (NTRS)

    Smith, David E.; Zuber, Maria T.

    1998-01-01

    Recent spacecraft missions to the Moon have significantly improved our knowledge of the lunar gravity and topography fields and have raised some new and old questions about the early lunar history. It has frequently been assumed that the shape of the Moon today reflects an earlier equilibrium state and that the Moon has retained some internal strength. Recent analysis indicating a superisostatic state of some lunar basins lends support to this hypothesis. On its simplest level the present shape of the Moon is slightly flattened by 2.2 +/- 0.2 km while its gravity field, represented by an equipotential surface, is flattened only about 0.5 km. The hydrostatic component to the flattening arising from the Moon's present-day rotation contributes only 7 m. This difference between the topographic shape of the Moon and the shape of its gravitational equipotential has frequently been explained as the "memory" of an earlier Moon that was rotating faster and had a correspondingly larger hydrostatic flattening. To obtain this amount of hydrostatic flattening from rotation alone, and accounting for the contribution of the present-day gravity field, the Moon's rotation rate would need to be about 15 times greater than at present leading to a period of under 2 days. Maintaining its synchronous rotation with Earth would require a radius for the Moon's orbit of order 9 earth radii. Unfortunately, our confidence in the observed lunar flattening is not as great as we would like.

  2. The effect of topography of polymer surfaces on platelet adhesion.

    PubMed

    Koh, Li Buay; Rodriguez, Isabel; Venkatraman, Subbu S

    2010-03-01

    In this study, the effect of surface topography on fibrinogen and platelet adsorption was investigated. High aspect ratio surface features, in the submicron to nanometer range, were constructed on the poly- (lactic-co-glycolic-acid) (PLGA) films. The topographic surfaces were fabricated by solvent-mediated polymer casting on a master template. Fibrinogen adsorption and platelets adhesion on these topographic surfaces were quantified by enzyme linked immunosorbent assay (ELISA) and lactate dehydrogenase (LDH) assay respectively, while the activation of platelets was quantified by flow cytometric analysis using fluorescein isothiocyanate (FITC) tagging. The lowest fibrinogen adsorption amount and platelet activity was observed on surfaces with specific topographical features in the submicron range with a significant reduction in adhesion when compared to the pristine PLGA films. The topographical parameters found to induce low levels of fibrinogen adsorption and platelet response were high aspect ratio structures (>3:1) with reduced interspacing (<200 nm) or high density. The results signify that topographical manipulation of thrombogenic surfaces of biodegradable polymers is a feasible approach for reducing their thrombogenicity. PMID:19945746

  3. Nanoscale topography of nanocrystalline diamonds promotes differentiation of osteoblasts.

    PubMed

    Kalbacova, M; Rezek, B; Baresova, V; Wolf-Brandstetter, C; Kromka, A

    2009-10-01

    The excellent mechanical, tribological and biochemical properties of diamond coatings are promising for improving orthopedic or stomatology implants. A crucial prerequisite for such applications is an understanding and control of the biological response of the diamond coatings. This study concentrates on the correlation of diamond surface properties with osteoblast behavior. Nanocrystalline diamond (NCD) films (grain size up to 200 nm, surface roughness 20 nm) were deposited on silicon substrates of varying roughnesses (1, 270 and 500 nm) and treated by oxygen plasma to generate a hydrophilic surface. Atomic force microscopy was used for topographical characterization of the films. As a reference surface, tissue culture polystyrene (PS) was used. Scanning electron microscopy and immunofluorescence staining was used to visualize cell morphological features as a function of culture time. Metabolic activity, alkaline phosphatase activity, and calcium and phosphate deposition was also monitored. The results show an enhanced osteoblast adhesion as well as increased differentiation (raised alkaline phosphatase activity and mineral deposition) on NCD surfaces (most significantly on RMS 20 nm) compared to PS. This is attributed mainly to the specific surface topography as well as to the biocompatible properties of diamond. Hence the controlled (topographically structured) diamond coating of various substrates is promising for preparation of better implants, which offer faster colonization by specific cells as well as longer-term stability. PMID:19433140

  4. Crustal structure of Mars from gravity and topography

    NASA Technical Reports Server (NTRS)

    Neumann, G. A.; Zuber, M. T.; Wieczorek, M. A.; McGovern, P. J.; Lemoine, F. G.; Smith, D. E.

    2004-01-01

    Mars Orbiter Laser Altimeter (MOLA) topography and gravity models from 5 years of Mars Global Surveyor (MGS) spacecraft tracking provide a window into the structure of the Martian crust and upper mantle. We apply a finite-amplitude terrain correction assuming uniform crustal density and additional corrections for the anomalous densities of the polar caps, the major volcanos, and the hydrostatic flattening of the core. A nonlinear inversion for Moho relief yields a crustal thickness model that obeys a plausible power law and resolves features as small as 300 km wavelength. On the basis of petrological and geophysical constraints, we invoke a mantle density contrast of 600 kg m-3; with this assumption, the Isidis and Hellas gravity anomalies constrain the global mean crustal thickness to be >45 km. The crust is characterized by a degree 1 structure that is several times larger than any higher degree harmonic component, representing the geophysical manifestation of the planet's hemispheric dichotomy. It corresponds to a distinction between modal crustal thicknesses of 32 km and 58 km in the northern and southern hemispheres, respectively. The Tharsis rise and Hellas annulus represent the strongest components in the degree 2 crustal thickness structure. A uniform highland crustal thickness suggests a single mechanism for its formation, with subsequent modification by the Hellas impact, erosion, and the volcanic construction of Tharsis. The largest surviving lowland impact, Utopia, post-dated formation of the crustal dichotomy. Its crustal structure is preserved, making it unlikely that the northern crust was subsequently thinned by internal processes.

  5. Determining Titan surface topography from Cassini SAR data

    USGS Publications Warehouse

    Stiles, Bryan W.; Hensley, Scott; Gim, Yonggyu; Bates, David M.; Kirk, Randolph L.; Hayes, Alex; Radebaugh, Jani; Lorenz, Ralph D.; Mitchell, Karl L.; Callahan, Philip S.; Zebker, Howard; Johnson, William T.K.; Wall, Stephen D.; Lunine, Jonathan I.; Wood, Charles A.; Janssen, Michael; Pelletier, Frederic; West, Richard D.; Veeramacheneni, Chandini

    2009-01-01

    A technique, referred to as SARTopo, has been developed for obtaining surface height estimates with 10 km horizontal resolution and 75 m vertical resolution of the surface of Titan along each Cassini Synthetic Aperture Radar (SAR) swath. We describe the technique and present maps of the co-located data sets. A global map and regional maps of Xanadu and the northern hemisphere hydrocarbon lakes district are included in the results. A strength of the technique is that it provides topographic information co-located with SAR imagery. Having a topographic context vastly improves the interpretability of the SAR imagery and is essential for understanding Titan. SARTopo is capable of estimating surface heights for most of the SAR-imaged surface of Titan. Currently nearly 30% of the surface is within 100 km of a SARTopo height profile. Other competing techniques provide orders of magnitude less coverage. We validate the SARTopo technique through comparison with known geomorphological features such as mountain ranges and craters, and by comparison with co-located nadir altimetry, including a 3000 km strip that had been observed by SAR a month earlier. In this area, the SARTopo and nadir altimetry data sets are co-located tightly (within 5-10 km for one 500 km section), have similar resolution, and as expected agree closely in surface height. Furthermore the region contains prominent high spatial resolution topography, so it provides an excellent test of the resolution and precision of both techniques.

  6. Wind-Related Topography in Phoenix's Region of Mars (Animation)

    NASA Technical Reports Server (NTRS)

    2008-01-01

    [figure removed for brevity, see original site] Click on image for animation

    This movie shifts from a global zoom indicating the Phoenix landing area on Mars to a topographical map indicating relative elevations in the landing region. The elevations could affect wind patterns at the site.

    In particular, Phoenix is in a broad, shallow valley. The edge of the valley, about 150 meters (500 feet) above the floor, may provide enough of a slope to the east of Phoenix to explain winds coming from the east during nights at the site. Cooler, denser air could be sinking down the slope and toward the lander.

    Atmospheric scientists on the Phoenix team are analyzing wind patterns to distiguish effects of nearby topography from larger-scale movement of the atmosphere in the polar region.

    The elevation information for this topographical mapping comes from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor orbiter. The blue-coded area is the valley floor. Orange and yellow indicate relatively higher elevations.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver. JPL managed the Mars Global Surveyor mission for the NASA Science Mission Directorate.

  7. Extraction of Martian valley networks from digital topography

    NASA Technical Reports Server (NTRS)

    Stepinski, T. F.; Collier, M. L.

    2004-01-01

    We have developed a novel method for delineating valley networks on Mars. The valleys are inferred from digital topography by an autonomous computer algorithm as drainage networks, instead of being manually mapped from images. Individual drainage basins are precisely defined and reconstructed to restore flow continuity disrupted by craters. Drainage networks are extracted from their underlying basins using the contributing area threshold method. We demonstrate that such drainage networks coincide with mapped valley networks verifying that valley networks are indeed drainage systems. Our procedure is capable of delineating and analyzing valley networks with unparalleled speed and consistency. We have applied this method to 28 Noachian locations on Mars exhibiting prominent valley networks. All extracted networks have a planar morphology similar to that of terrestrial river networks. They are characterized by a drainage density of approx.0.1/km, low in comparison to the drainage density of terrestrial river networks. Slopes of "streams" in Martian valley networks decrease downstream at a slower rate than slopes of streams in terrestrial river networks. This analysis, based on a sizable data set of valley networks, reveals that although valley networks have some features pointing to their origin by precipitation-fed runoff erosion, their quantitative characteristics suggest that precipitation intensity and/or longevity of past pluvial climate were inadequate to develop mature drainage basins on Mars.

  8. Accuracy of the PAR corneal topography system with spatial misalignment.

    PubMed

    Belin, M W; Zloty, P

    1993-01-01

    The PAR Corneal Topography System is a computerized corneal imaging system which uses close-range raster photogrammetry to measure and produce a topographic map of the corneal surface. Raster photogrammetry is a standard method of extracting object information by projecting a known pattern onto an object and recording the distortion when viewed from an oblique angle. Unlike placido disc based videokeratoscopes, the PAR system requires neither a smooth reflective surface nor precise spatial alignment for accurate imaging. We studied both the accuracy of the system with purposeful misalignment (defocusing) of the test object and determined the ability to image freshly deepithelialized, keratectomized, and photoablated corneas. The PAR system was both accurate and reproducible in imaging calibrated spheres within a defined zone in space. Whole cadaver eyes were imaged both before and immediately after removal of the epithelium, lamellar keratectomy, and laser photoablation. The system demonstrated the ability to image irregular, deepithelialized, and keratectomized corneas. The ability to maintain accuracy without precise alignment and the facility to image freshly deepithelialized and keratectomized corneas may make the system suitable for intraoperative refractive monitoring. PMID:8453756

  9. Corneal topography reinterpretation through separate analysis of the projected rings

    NASA Astrophysics Data System (ADS)

    Espinosa, Julian; Roig, Ana B.; Mas, David; Hernández, Consuelo; Illueca, Carlos

    2012-06-01

    We present a new algorithm to process captured images of reflected Placido rings. Up to our knowledge, conventional topographers transform from Cartesian to polar coordinates and vice-versa, thus extrapolating corneal data and introducing noise and image artefacts. Moreover, captured data are processed by the device according to proprietary algorithms and offering a final map of corneal curvature. Corneal topography images consists of concentric rings of approximately elliptical shape. Our proposal consists of considering the information that provides each separate ring. A snake-annealing-like method permits identifying the ring even with discontinuities due to eye-lashes and reflections. By analysing the geometrical parameters of rings (centre, semi-axis and orientation), one can obtain information about small morphological micro-fluctuations and local astigmatisms. These parameters can be obtained with sub-pixel accuracy so the method results of high precision. The method can be easily adapted to work on any topographer, so that it can provide additional information about the cornea at no additional cost.

  10. OCT 3-D surface topography of isolated human crystalline lenses

    PubMed Central

    Sun, Mengchan; Birkenfeld, Judith; de Castro, Alberto; Ortiz, Sergio; Marcos, Susana

    2014-01-01

    Quantitative 3-D Optical Coherence Tomography was used to measure surface topography of 36 isolated human lenses, and to evaluate the relationship between anterior and posterior lens surface shape and their changes with age. All lens surfaces were fitted to 6th order Zernike polynomials. Astigmatism was the predominant surface aberration in anterior and posterior lens surfaces (accounting for ~55% and ~63% of the variance respectively), followed by spherical terms, coma, trefoil and tetrafoil. The amount of anterior and posterior surface astigmatism did not vary significantly with age. The relative angle between anterior and posterior surface astigmatism axes was on average 36.5 deg, tended to decrease with age, and was >45 deg in 36.1% lenses. The anterior surface RMS spherical term, RMS coma and 3rd order RMS decreased significantly with age. In general, there was a statistically significant correlation between the 3rd and 4th order terms of the anterior and posterior surfaces. Understanding the coordination of anterior and posterior lens surface geometries and their topographical changes with age sheds light into the role of the lens in the optical properties of the eye and the lens aging mechanism. PMID:25360371

  11. OCT 3-D surface topography of isolated human crystalline lenses.

    PubMed

    Sun, Mengchan; Birkenfeld, Judith; de Castro, Alberto; Ortiz, Sergio; Marcos, Susana

    2014-10-01

    Quantitative 3-D Optical Coherence Tomography was used to measure surface topography of 36 isolated human lenses, and to evaluate the relationship between anterior and posterior lens surface shape and their changes with age. All lens surfaces were fitted to 6th order Zernike polynomials. Astigmatism was the predominant surface aberration in anterior and posterior lens surfaces (accounting for ~55% and ~63% of the variance respectively), followed by spherical terms, coma, trefoil and tetrafoil. The amount of anterior and posterior surface astigmatism did not vary significantly with age. The relative angle between anterior and posterior surface astigmatism axes was on average 36.5 deg, tended to decrease with age, and was >45 deg in 36.1% lenses. The anterior surface RMS spherical term, RMS coma and 3rd order RMS decreased significantly with age. In general, there was a statistically significant correlation between the 3rd and 4th order terms of the anterior and posterior surfaces. Understanding the coordination of anterior and posterior lens surface geometries and their topographical changes with age sheds light into the role of the lens in the optical properties of the eye and the lens aging mechanism. PMID:25360371

  12. The effect of topography on pyroclastic flow mobility

    NASA Astrophysics Data System (ADS)

    Ogburn, S. E.; Calder, E. S.

    2010-12-01

    Pyroclastic flows are among the most destructive volcanic phenomena. Hazard mitigation depends upon accurate forecasting of possible flow paths, often using computational models. Two main metrics have been proposed to describe the mobility of pyroclastic flows. The Heim coefficient, height-dropped/run-out (H/L), exhibits an inverse relationship with flow volume. This coefficient corresponds to the coefficient of friction and informs computational models that use Coulomb friction laws. Another mobility measure states that with constant shear stress, planimetric area is proportional to the flow volume raised to the 2/3 power (A?V^(2/3)). This relationship is incorporated in models using constant shear stress instead of constant friction, and used directly by some empirical models. Pyroclastic flows from Soufriere Hills Volcano, Montserrat; Unzen, Japan; Colima, Mexico; and Augustine, Alaska are well described by these metrics. However, flows in specific valleys exhibit differences in mobility. This study investigates the effect of topography on pyroclastic flow mobility, as measured by the above mentioned mobility metrics. Valley width, depth, and cross-sectional area all influence flow mobility. Investigating the appropriateness of these mobility measures, as well as the computational models they inform, indicates certain circumstances under which each model performs optimally. Knowing which conditions call for which models allows for better model selection or model weighting, and therefore, more realistic hazard predictions.

  13. A fractal interpretation of topography and geoid spectra on the earth, moon, Venus, and Mars

    NASA Technical Reports Server (NTRS)

    Turcotte, Donald L.

    1987-01-01

    Global spectra are available for topography and geoid on the earth, Venus, Mars, and the moon. If the spectral energy density has a power law dependence on wave number, a fractal is defined. The topography spectrum for the earth is a well-defined fractal with D = 1.5; this corresponds to Brown noise with the amplitude proportional to the wavelength. Although there is more scatter for the other planetary bodies, the data for Mars and the moon correlate well with the data for the earth. Venus topography also exhibits a Brown noise behavior but with a smaller amplitude. The power law dependence of the earth's geoid is known as Kaula's law. It is shown that uncompensated Brown topography gives a geoid with a power law dependence that is in quite good agreement with Kaula's law. However, the required amplitude is only 8 percent of the observed topography. A similar result is found for the other bodies, with the ratio of the amplitude of topography required to explain the geoid to the observed topography increasing to 72 percent for the moon.

  14. A non-periodic two scale asymptotic method to take account of rough topographies for 2-D elastic wave propagation

    NASA Astrophysics Data System (ADS)

    Capdeville, Yann; Marigo, Jean-Jacques

    2013-01-01

    We propose a two scale asymptotic method to compute the effective effect of a free surface topography varying much faster than the minimum wavelength for 2-D P-SV elastic wave propagation. The topography variation is assumed to be non-periodic but with a deterministic description and, in this paper, the elastic body below the topography is assumed to be homogeneous. Two asymptotic expansions are used, one in the boundary layer close to the free surface and one in the volume. Both expansions are matched appropriately up to the order 1 to provide an effective topography and an effective boundary condition. We show that the effective topography is not the averaged topography but it is a smooth free surface lying below the fast variations of the real topography. Moreover, the free boundary condition has to be modified to take account of the inertial effects of the fast variations of the topography above the effective topography. In other words, the wave is not propagating in the fast topography but below it and is slowed down by the weight of the fast topography. We present an iterative scheme allowing to find this effective topography for a given minimum wavelength. We do not attempt any mathematical proof of the proposed scheme, nevertheless, numerical tests show good results.

  15. The Mystery of the Mars North Polar Gravity-Topography Correlation(Or Lack Thereof)

    NASA Technical Reports Server (NTRS)

    Phillips, R. J.; Sjogren, W. L.; Johnson, C. L.

    1999-01-01

    Maps of moderately high resolution gravity data obtained from the Mars Global Surveyor (MGS) gravity calibration orbit campaign and high precision topography obtained from the Mars Orbiter Laser Altimeter (MOLA) experiment reveal relationships between gravity and topography in high northern latitudes of Mars. Figure 1 shows the results of a JPL spherical harmonic gravity model bandpass filtered between degrees 6 and 50 contoured over a MOLA topographic image. A positive gravity anomaly exists over the main North Polar cap, but there are at least six additional positive gravity anomalies, as well as a number of smaller negative anomalies, with no obvious correlation to topography. Additional information is contained in the original extended abstract.

  16. Understanding the mechanisms of solid-water reactions through analysis of surface topography

    NASA Astrophysics Data System (ADS)

    Bandstra, Joel Z.; Brantley, Susan L.

    2015-12-01

    The topography of a reactive surface contains information about the reactions that form or modify the surface and, therefore, it should be possible to characterize reactivity using topography parameters such as surface area, roughness, or fractal dimension. As a test of this idea, we consider a two-dimensional (2D) lattice model for crystal dissolution and examine a suite of topography parameters to determine which may be useful for predicting rates and mechanisms of dissolution. The model is based on the assumption that the reactivity of a surface site decreases with the number of nearest neighbors. We show that the steady-state surface topography in our model system is a function of, at most, two variables: the ratio of the rate of loss of sites with two neighbors versus three neighbors (d2/d3) and the ratio of the rate of loss of sites with one neighbor versus three neighbors (d1/d3) . This means that relative rates can be determined from two parameters characterizing the topography of a surface provided that the two parameters are independent of one another. It also means that absolute rates cannot be determined from measurements of surface topography alone. To identify independent sets of topography parameters, we simulated surfaces from a broad range of d1/d3 and d2/d3 and computed a suite of common topography parameters for each surface. Our results indicate that the fractal dimension D and the average spacing between steps, E [s ] , can serve to uniquely determine d1/d3 and d2/d3 provided that sufficiently strong correlations exist between the steps. Sufficiently strong correlations exist in our model system when D >1.5 (which corresponds to D >2.5 for real 3D reactive surfaces). When steps are uncorrelated, surface topography becomes independent of step retreat rate and D is equal to 1.5. Under these conditions, measures of surface topography are not independent and any single topography parameter contains all of the available mechanistic information about the surface. Our results also indicate that root-mean-square roughness cannot be used to reliably characterize the surface topography of fractal surfaces because it is an inherently noisy parameter for such surfaces with the scale of the noise being independent of length scale.

  17. The origin of the Iberian microplate high topography

    NASA Astrophysics Data System (ADS)

    Quintana, L.; Pulgar, J. A.; Alonso, J. L.; Fernandez Viejo, G.

    2013-12-01

    The Iberian microplate is about 1100 km width, 3500 km long, and experienced contraction during the Cenozoic convergence of the Eurasian and African plates. In this process two main mountain ranges were created in the boundaries of the microplate: the Cantabrian-Pyrenean range in the north and the Betic-Rif orogenic system in the south, with a maximun height of 3479 m over sea level. However, in the interior of the microplate there is also several ranges and plateaus, with maximun heights of 2592 m. The origin of these interior high topography is controversial and has been explained by means of several procesess as: a) transference of displacement from the south border of the microplate, b) lithospheric folding, or c) more complex deep mantle related processes. In this work we investigate the relation between the northern border range of the microplate and some Iberian interior reliefs as: a) the Spanish Central System range, located in the central part of the microplate, with peaks over 2500 m, and b) the North-Iberian meseta, situated between these two ranges, and with average heights of 750 m. In order to solve this relation we have built a crustal-scale cross-section, through the northern half of the Iberian microplate, by using field geological mapping, subsoil information and deep geophysical data. The section acroos the central part of the Cantabrian range shows the well-known Iberian microplate continental subduction beneath the Eurasian plate, with a prominent crustal root that reaches up to 45 km depth. In this section an important difference between the upper and lower crust shortening values has been found. Thus, the upper crust has been shortened 97 km while the lower crust 122 km. The section across de Central System range shows a slightly thickened crust. In this range also exist a difference in the shortening values between upper and lower crust, but in the contrary sense than the Cantabrian range. Thus, the Central System range has been shortened between 24-50 km in the upper crust, while the lower crust shows minor shortening. To solve this controversy, we propose that the Cantabrian and the Central System ranges are connected through a middle crustal detachment, 300 km long, beneath the North-Iberian meseta. Thus the default of shortening of the Central System lower crust is balanced by the excess of shortening of the Cantabrian lower crust subduction. At the same time we propose that the middle crustal detachment is not horizonal but rather a very low angle ramp dipping to the north. With this geometry we explain also the uplift of the North-Iberian meseta.We conclude that the mechanism that best explain the origin of the Iberian microplate interior high topography is the transference of displacement from the border ranges to the interior ones of the microplate.

  18. Modeling Floods in Athabasca Valles, Mars, Using CTX Stereo Topography

    NASA Astrophysics Data System (ADS)

    Dundas, C. M.; Keszthelyi, L. P.; Denlinger, R. P.; Thomas, O. H.; Galuszka, D.; Hare, T. M.; Kirk, R. L.; Howington-Kraus, E.; Rosiek, M.

    2012-12-01

    Among the most remarkable landforms on Mars are the outflow channels, which suggest the occurrence of catastrophic water floods in the past. Athabasca Valles has long been thought to be the youngest of these channels [1-2], although it has recently become clear that the young crater age applies to a coating lava flow [3]. Simulations with a 2.5-dimensional flood model have provided insight into the details of flood dynamics but have also demonstrated that the Digital Elevation Model (DEM) from the Mars Orbiter Laser Altimeter (MOLA) Mission Experiment Gridded Data Records includes significant artifacts at this latitude at the scales relevant for flood modeling [4]. In order to obtain improved topography, we processed stereo images from the Context Camera (CTX) of the Mars Reconnaissance Orbiter (MRO) using methods developed for producing topographic models of the Moon with images from the Lunar Reconnaissance Orbiter Camera, a derivative of the CTX camera. Some work on flood modeling with CTX stereo has been published by [5], but we will present several advances, including corrections to the published CTX optical distortion model and improved methods to combine the stereo and MOLA data. The limitations of current methods are the accuracy of control to MOLA and the level of error introduced when the MRO spacecraft is not in a high-stability mode during stereo imaging, leading to jitter impacting the derived topography. Construction of a mosaic of multiple stereo pairs, controlled to MOLA, allows us to consider flow through the cluster of streamlined islands in the upper part of the channel [6], including what is suggested to be the best example of flood-formed subaqueous dunes on Mars [7]. We will present results from running a flood model [4, 8] through the high-resolution (100 m/post) DEM covering the streamlined islands and subaqueous dunes, using results from a lower-resolution model as a guide to the inflow. By considering a range of flow levels below estimated peak flow, we can examine the flow behavior at the site of the apparent subaqueous dunes and, in particular, assess whether the flow in this area is uniquely conducive to the formation of such bedforms [e.g., 9]. [1] Berman D. C. and Hartmann W. K. (2002) Icarus 159, 1-17. [2] Burr D. M. et al. (2002) Icarus 159, 53-73. [3] Jaeger W. L. et al. (2010) Icarus 205, 230-243. [4] Keszthelyi L. P. et al. (2007) GRL 34, L21206. [5] McIntyre et al. (2012) JGR 117, E03009. [6] Burr D. (2005) Geomorphology 69, 242-252. [7] Burr D. M. et al. (2004) Icarus 171, 68-83. [8] Denlinger R. P. and O'Connell D. R. H. (2008) J. Hyd. Eng. 134, 1590-1602. [9] Kleinhans M. G. (2005) JGR 110, E12003.

  19. Venus Topography in 3D: Imaging of Coronae and Chasmata

    NASA Astrophysics Data System (ADS)

    Jurdy, D. M.; Stefanick, M.; Stoddard, P. R.

    2006-12-01

    Venus' surface hosts hundreds of circular to elongate features, ranging from 60-2600 km, and averaging somewhat over 200 km, in diameter. These enigmatic structures have been classified as "coronae" and attributed to either tectono-volcanic or impact-related mechanisms. A linear to arcuate system of chasmata - rugged zones with some of Venus' deepest troughs, extend 1000's of kilometers. They have extreme relief, with elevations changing as much as 7 km in just 30 km distance. The 54,464 km-long Venus chasmata system defined in great detail by Magellan can be fit by great circle arcs at the 89.6% level, and when corrected for the smaller size of the planet, the total length of the chasmata system measures within 2.7% of the length of Earth's spreading ridges. The relatively young Beta-Atla-Themis region (BAT), within 30 of the equator from 180-300 longitude has the planet's strongest geoid highs and profuse volcanism. This BAT region, the intersection of three rift zones, also has a high coronal concentration, with individual coronae closely associated with the chasmata system. The chasmata with the greatest relief on Venus show linear rifting that prevailed in the latest stage of tectonic deformation. For a three-dimensional view of Venus' surface, we spread out the Magellan topography on a flat surface using a Mercator projection to preserve shape. Next we illuminate the surface with beams at angle 45 from left (or right) so as to simulate mid afternoon (or mid-morning). Finally, we observe the surface with two eyes looking through orange and azure colored filters respectively. This gives a 3D view of tectonic features in the BAT area. The 3D images clearly show coronae sharing boundaries with the chasmata. This suggests that the processes of rifting and corona-formation occur together. It seems unlikely that impact craters would create this pattern.

  20. Accuracy of Sea Surface Topography with GPS Scattered Signals

    NASA Astrophysics Data System (ADS)

    Zuffada, C.; Zavorotny, V. U.; Lowe, S.

    2001-12-01

    The concept of using GPS reflected signals for ocean and land remote sensing is based on the use of one airborne (or space-based) GPS receiver working simultaneously with a constellation of several signal-transmitting GPS satellites. This would offer an advantage in terms of spatial coverage compared to a conventional monostatic radar system and possibly allow new scientific applications to be pursued. However, the limited power of GPS transmitters and a relatively low surface cross section would require either large receiving antennas or longer integration times to optimize the signal-to-noise ratio. Analogously to the case of a conventional radar altimeter, the reflected GPS signal acquired by the receiver is the average power versus time (a range measurement) and generally represents the contributions from surfaces which scatter incoherently. This waveform is derived as a function of viewing geometry, system parameters, surface roughness and dielectric properties of underlying covers. This work investigates the spatial-temporal coherence properties and statistics of the measured reflected GPS signal that describes variability from one sample to another. This information is needed to choose an optimal strategy for a successful signal processing. We examine the above-mentioned properties of the modeled received power as a function of surface state and scattering geometry. Its impact on the accuracy of sea surface topography, both from airborne and orbital platforms is addressed. A characterization of error and expected spatial resolution in relation to existing instruments is discussed. Furthermore, in examining the coherence time, we analyze the spectral behavior of the reflected signal versus sea state parameters, such as wind vector. In addition, we compare the predictions with data available from recent airplane measurements taken in the Pacific Ocean off the coast of Southern California obtaining preliminary validations of our models.

  1. Manometric features of Eosinophilic Esophagitis in Esophageal Pressure Topography

    PubMed Central

    Roman, Sabine; Hirano, Ikuo; Kwiatek, Monika A; Gonsalves, Nirmala; Chen, Joan; Kahrilas, Peter J; Pandolfino, John E

    2010-01-01

    Backgrounds Although most patients with EoE have mucosal and structural changes that could potentially explain their symptoms, it is unclear whether EoE is associated with abnormal esophageal motor function. The aims of this study were to evaluate the esophageal pressure topography (EPT) findings in EoE and to compare them with controls and patients with gastro-esophageal disease (GERD). Methods EPT studies in 48 EoE patients, 48 GERD patients and 50 controls were compared. The esophageal contractile pattern was described for ten 5-ml swallows for each subject and each swallow was secondarily characterized based on the bolus pressurization pattern: absent, pan-esophageal pressurization, or compartmentalized distal pressurization. Key Results 37% of EoE patients were classified as having abnormal esophageal motility. The most frequent diagnoses were of weak peristalsis and frequent failed peristalsis. Although motility disorders were more frequent in EoE patients than in controls, the prevalence and type were similar to those observed in GERD patients (p=0.61, Chi square test). Pan-esophageal pressurization was present in 17% of EoE and 2% of GERD patients while compartmentalized pressurization was present in 19% of EoE and 10% of GERD patients. These patterns were not seen in control subjects. Conclusions & Inferences The prevalence of abnormal esophageal motility in EoE was approximately 37% and was similar in frequency and type to motor patterns observed in GERD. EoE patients were more likely to have abnormal bolus pressurization patterns during swallowing and we hypothesize that this may be a manifestation of reduced esophageal compliance. PMID:21091849

  2. Erosion of Terrestrial Rift Flank Topography: A Quantitative Study

    NASA Technical Reports Server (NTRS)

    Weissel, Jeffrey K.

    1999-01-01

    Many rifted or passive continental margins feature a seaward-facing erosional escarpment which abruptly demarcates deeply weathered, low relief, interior uplands from a deeply incised, high relief coastal zone. It is generally accepted that these escarpments originate at the time of continental rifting and propagate inland through the elevated rift flank topography at rates on the order of 1 km/Myr over the course of a margin's history. Considering the length of passive margins worldwide and an average rift flank plateau height of several hundred meters, it is clear that sediment eroded from passive margins is an important component of the mass flux from continents to oceans through geologic time. The overall goal of the research reported here is to develop a quantitative understanding of the kinematics of escarpment propagation across passive margins and the underlying geological processes responsible for this behavior. Plateau-bounding escarpments in general exhibit two basic forms depending on the direction of surface water drainage on the plateau interior relative to the escarpment. Where surface water flows away from the escarpment, the escarpment takes the form of subdued embayments and promontories, such that its overall trend remains fairly straight as it evolves with time. Where upland streams flow across the escarpment, it takes the form of dramatic, narrow gorges whose heads appear to propagate up the plateau drainage systems as large-scale knickpoints. From work on the Colorado Plateau, Schmidt (1987) noted that the Colorado River is located much closer to the Grand Canyon's south rim, a drainage divide escarpment, than to the north rim, which is a gorge-like escarpment. The main implication is that the gorge-like form might be associated with higher long-term average erosion rates compared to the drainage divide escarpment type.

  3. Mapping the Topography of Mercury with MESSENGER Laser Altimetry

    NASA Technical Reports Server (NTRS)

    Sun, Xiaoli; Cavanaugh, John F.; Neumann, Gregory A.; Smith, David E..; Zubor, Maria T.

    2012-01-01

    The Mercury Laser Altimeter onboard MESSENGER involves unique design elements that deal with the challenges of being in orbit around Mercury. The Mercury Laser Altimeter (MLA) is one of seven instruments on NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. MESSENGER was launched on 3 August 2004, and entered into orbit about Mercury on 18 March 2011 after a journey through the inner solar system. This involved six planetary flybys, including three of Mercury. MLA is designed to map the topography and landforms of Mercury's surface. It also measures the planet's forced libration (motion about the spin axis), which helps constrain the state of the core. The first science measurements from orbit taken with MLA were made on 29 March 2011 and continue to date. MLA had accumulated about 8.3 million laser ranging measurements to Mercury's surface, as of 31 July 2012, i.e., over six Mercury years (528 Earth days). Although MLA is the third planetary lidar built at the NASA Goddard Space Flight Center (GSFC), MLA must endure a much harsher thermal environment near Mercury than the previous instruments on Mars and Earth satellites. The design of MLA was derived in part from that of the Mars Orbiter Laser Altimeter on Mars Global Surveyor. However, MLA must range over greater distances and often in off-nadir directions from a highly eccentric orbit. In MLA we use a single-mode diode-pumped Nd:YAG (neodymium-doped yttrium aluminum garnet) laser that is highly collimated to maintain a small footprint on the planet. The receiver has both a narrow field of view and a narrow spectral bandwidth to minimize the amount of background light detected from the sunlit hemisphere of Mercury. We achieve the highest possible receiver sensitivity by employing the minimum receiver detection threshold.

  4. Mapping the Topography of a Protein Energy Landscape.

    PubMed

    Hutton, Richard D; Wilkinson, James; Faccin, Mauro; Sivertsson, Elin M; Pelizzola, Alessandro; Lowe, Alan R; Bruscolini, Pierpaolo; Itzhaki, Laura S

    2015-11-25

    Protein energy landscapes are highly complex, yet the vast majority of states within them tend to be invisible to experimentalists. Here, using site-directed mutagenesis and exploiting the simplicity of tandem-repeat protein structures, we delineate a network of these states and the routes between them. We show that our target, gankyrin, a 226-residue 7-ankyrin-repeat protein, can access two alternative (un)folding pathways. We resolve intermediates as well as transition states, constituting a comprehensive series of snapshots that map early and late stages of the two pathways and show both to be polarized such that the repeat array progressively unravels from one end of the molecule or the other. Strikingly, we find that the protein folds via one pathway but unfolds via a different one. The origins of this behavior can be rationalized using the numerical results of a simple statistical mechanics model that allows us to visualize the equilibrium behavior as well as single-molecule folding/unfolding trajectories, thereby filling in the gaps that are not accessible to direct experimental observation. Our study highlights the complexity of repeat-protein folding arising from their symmetrical structures; at the same time, however, this structural simplicity enables us to dissect the complexity and thereby map the precise topography of the energy landscape in full breadth and remarkable detail. That we can recapitulate the key features of the folding mechanism by computational analysis of the native structure alone will help toward the ultimate goal of designed amino-acid sequences with made-to-measure folding mechanisms-the Holy Grail of protein folding. PMID:26561984

  5. A magmatic probe of dynamic topography beneath western North America

    NASA Astrophysics Data System (ADS)

    Klcking, M.; White, N. J.; Maclennan, J.

    2014-12-01

    A region centered on the Yellowstone hotspot and encompassing the Colorado Plateau sits at an elevation 2 km higher than the cratonic North America. This difference broadly coincides with tomographically observed variations in lithospheric thickness: ~120 km beneath western North America, ~240 km beneath the craton. Thermochronology of the Grand Canyon area, sedimentary flux to the Gulf of Mexico, and river profile inversion all suggest that regional uplift occurred in at least two separate stages. High resolution seismic tomographic models, using USArray data, have identified a ring of low velocity material beneath the edges of the Colorado Plateau. Magmatism coincides with these low velocity zones and shows distinct phases: an overall increase in volume around 40 Ma and a change from lithospheric to asthenospheric signatures around 5 Ma. Volcanism is also observed to migrate north-east with time. Here, we attempt to integrate these different observations with lithospheric thickness. A dynamic topography model of progressive lithospheric erosion over a hot mantle plume might account for uplift as well as the temporal and spatial distribution of magmatism across western North America. Thinning of the lithosphere around the edges of the Colorado Plateau in combination with the hotter mantle potential temperature of a plume could create isostatic and dynamic uplift as well as allowing for melt production. To test this model, we have analysed around 100 samples from volcanic centers across western North America by ICP-MS for rare earth elements (REE). Most of the samples are younger than 5 Ma, and all of them have previously been analysed by XRF. Using trace element ratios such as La/Yb and Nb/Y we assess depth of melting and melt fraction, respectively. In addition, we use REE inversion modelling to estimate melt fractions as a function of depth and temperature of melting. The results are compared to existing constraints on lithospheric thickness and mantle potential temperature.

  6. Digital signal processing in AFM topography and recognition imaging

    NASA Astrophysics Data System (ADS)

    Adamsmair, Stefan; Ebner, Andreas; Hinterdorfer, Peter; Zagar, Bernhard

    2005-10-01

    Atomic force microscopy (AFM) has proven to be a powerful tool to observe topographical details at the nano- and subnanometer scale. Since this is a rather new technique, new enhancements with faster scanning rates, more accurate measurements and more detailed information were developed. This requires also a higher demand on the signal processing and the controlling software. Operating an AFM with analog driven hardware is often limited by drift and noise problems. Here we overcome this problem by introducing digital signal processing capable of accurately stabilizing the piezo control in the newly developed TREC (topography and recognition imaging) mode. In this mode topographical information and molecular recognition between tip bound ligand and surface bound receptors is simultaneously acquired. The sought information is conveyed by slight variations of the minima and maxima of the signal amplitudes. These variations are very small compared to the maximum possible DC deflection. Furthermore, the DC offset exhibits a rather large drift mostly attributed to temperature changes. To obtain reliable tracking results the oscillating photodiode signal needs to be nonlinearly filtered and efficiently separated into four major components: the maxima, the minima, the spatial average of the maxima, and the spatial average of the minima. The recognition image is then obtained by a nonlinear combination of these four components evaluated at spatial locations derived from the zero-crossings of the differentiated signal resulting from a modified differentiator FIR filter. Furthermore, to reliably estimate the DC drift an exponential tracking of the extrema by a first-order IIR filter is performed. The applicability of the proposed algorithms is demonstrated for biotin and avidin.

  7. Eye Morphology and Retinal Topography in Hummingbirds (Trochilidae: Aves).

    PubMed

    Lisney, Thomas J; Wylie, Douglas R; Kolominsky, Jeffrey; Iwaniuk, Andrew N

    2015-01-01

    Hummingbirds are a group of small, highly specialized birds that display a range of adaptations to their nectarivorous lifestyle. Vision plays a key role in hummingbird feeding and hovering behaviours, yet very little is known about the visual systems of these birds. In this study, we measured eye morphology in 5 hummingbird species. For 2 of these species, we used stereology and retinal whole mounts to study the topographic distribution of neurons in the ganglion cell layer. Eye morphology (expressed as the ratio of corneal diameter to eye transverse diameter) was similar among all 5 species and was within the range previously documented for diurnal birds. Retinal topography was similar in Amazilia tzacatl and Calypte anna. Both species had 2 specialized retinal regions of high neuron density: a central region located slightly dorso-nasal to the superior pole of the pecten, where densities reached ?45,000 cellsmm-2, and a temporal area with lower densities (38,000-39,000 cellsmm-2). A weak visual streak bridged the two high-density areas. A retina from Phaethornis superciliosus also had a central high-density area with a similar peak neuron density. Estimates of spatial resolving power for all 3 species were similar, at approximately 5-6 cyclesdegree-1. Retinal cross sections confirmed that the central high-density region in C. anna contains a fovea, but not the temporal area. We found no evidence of a second, less well-developed fovea located close to the temporal retina margin. The central and temporal areas of high neuron density allow for increased spatial resolution in the lateral and frontal visual fields, respectively. Increased resolution in the frontal field in particular may be important for mediating feeding behaviors such as aerial docking with flowers and catching small insects. PMID:26587582

  8. Leveraging High Resolution Topography for Education and Outreach: Updates to OpenTopography to make EarthScope and Other Lidar Datasets more Prominent in Geoscience Education

    NASA Astrophysics Data System (ADS)

    Kleber, E.; Crosby, C. J.; Arrowsmith, R.; Robinson, S.; Haddad, D. E.

    2013-12-01

    The use of Light Detection and Ranging (lidar) derived topography has become an indispensable tool in Earth science research. The collection of high-resolution lidar topography from an airborne or terrestrial platform allows landscapes and landforms to be represented at sub-meter resolution and in three dimensions. In addition to its high value for scientific research, lidar derived topography has tremendous potential as a tool for Earth science education. Recent science education initiatives and a community call for access to research-level data make the time ripe to expose lidar data and derived data products as a teaching tool. High resolution topographic data fosters several Disciplinary Core Ideas (DCIs) of the Next Generation Science Standards (NGS, 2013), presents respective Big Ideas of the new community-driven Earth Science Literacy Initiative (ESLI, 2009), teaches to a number National Science Education Standards (NSES, 1996), and Benchmarks for Science Literacy (AAAS, 1993) for science education for undergraduate physical and environmental earth science classes. The spatial context of lidar data complements concepts like visualization, place-based learning, inquiry based teaching and active learning essential to teaching in the geosciences. As official host to EarthScope lidar datasets for tectonically active areas in the western United States, the NSF-funded OpenTopography facility provides user-friendly access to a wealth of data that is easily incorporated into Earth science educational materials. OpenTopography (www.opentopography.org), in collaboration with EarthScope, has developed education and outreach activities to foster teacher, student and researcher utilization of lidar data. These educational resources use lidar data coupled with free tools such as Google Earth to provide a means for students and the interested public to visualize and explore Earth's surface in an interactive manner not possible with most other remotely sensed imagery. The education section of the OpenTopography portal has recently been strengthened with the addition of several new resources and the re-organization of existing content for easy discovery. New resources include a detailed frequently asked questions (FAQ) section, updated 'How-to' videos for downloading data from OpenTopography and additional webpages aimed at students, educators and researchers leveraging existing and updated resources from OpenTopography, EarthScope and other organizations. In addition, the OpenLandform catalog, an online collection of classic geologic landforms depicted in lidar, has been updated to include additional tectonic landforms from EarthScope lidar datasets.

  9. Corneal topography measurement by means of radial shearing interference: Part II - experiment results

    NASA Astrophysics Data System (ADS)

    Garncarz, Beata E.; Kowalik, Waldemar W.; Kasprzak, Henryk T.

    The method of the measurement of the corneal topography was worked out. This measurement system uses an interferometer based on radial shearing. This paper presents the preliminary results of the experiments. The results are compared with other methods.

  10. Modeling surface winds in mountainous catchments as a function of topography and vegetation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to develop accurate distributed hydrological models, spatially accurate meteorological forcing fields are required. In mountainous basins, elevation and topography strongly influence temperature, precipitation, vapor pressure, and wind. At the watershed scale, temperature, precipitation, ...

  11. Exact three-dimensional spectral solution to surface-groundwater interactions with arbitrary surface topography

    USGS Publications Warehouse

    Worman, A.; Packman, A.I.; Marklund, L.; Harvey, J.W.; Stone, S.H.

    2006-01-01

    It has been long known that land surface topography governs both groundwater flow patterns at the regional-to-continental scale and on smaller scales such as in the hyporheic zone of streams. Here we show that the surface topography can be separated in a Fourier-series spectrum that provides an exact solution of the underlying three-dimensional groundwater flows. The new spectral solution offers a practical tool for fast calculation of subsurface flows in different hydrological applications and provides a theoretical platform for advancing conceptual understanding of the effect of landscape topography on subsurface flows. We also show how the spectrum of surface topography influences the residence time distribution for subsurface flows. The study indicates that the subsurface head variation decays exponentially with depth faster than it would with equivalent two-dimensional features, resulting in a shallower flow interaction. Copyright 2006 by the American Geophysical Union.

  12. Convection-driven compaction as a possible origin of Enceladus's long wavelength topography

    NASA Astrophysics Data System (ADS)

    Besserer, J.; Nimmo, F.; Roberts, J. H.; Pappalardo, R. T.

    2013-05-01

    The long wavelength surface topography of Enceladus shows depressions about 1 km in depth and 102 km wide. One possible cause of this topography is spatially variable amounts of compaction of an initially porous ice shell, driven by spatial variations in heat flux. Here, we show that the heat flux variations associated with convection in the shell can quantitatively match the observed features. We develop a simple model of viscous compaction that includes the effect of porosity on thermal conductivity, and find that an initial shell porosity of at least 20-25% is required to develop the observed topography over 1 Ga. This mechanism produces topographic depressions, not rises, above convective upwellings, and does not generate detectable gravity anomalies. Unlike transient dynamic topography, it can potentially leave a permanent record of ancient convective processes in the shallow lithospheres of icy satellites.

  13. Emplacement of Long Lava Flows: Detailed Topography of the Carrizozo Basalt Lava Flow, New Mexico

    NASA Technical Reports Server (NTRS)

    Zimbelman, J. R; Johnston, A. K.

    2000-01-01

    The Carrizozo flow in south-central New Mexico was examined to obtain detailed topography for a long basaltic lava flow. This information will be helpful in evaluating emplacement models for long lava flows.

  14. Highest Resolution Topography of 433 Eros and Implications for MUSES-C

    NASA Astrophysics Data System (ADS)

    Cheng, A. F.; Barnouin-Jha, O.

    2003-03-01

    The highest resolution observations of surface morphology and topography of Eros from the NEAR landing provide unique information on rock distributions and landing hazards. The rock areal coverage is 18%, and one topographic feature would have been hazardous.

  15. Tectonics of the Tharsis Region of Mars: Insights from MGS Topography and Gravity

    NASA Technical Reports Server (NTRS)

    Banerdt, W. Bruce; Golombek, Matthew P.

    2000-01-01

    We have investigated the Tharsis region using gravity, topography, and geology to constrain a spherical thin shell model. We find that Tharsis likely formed primarily by volcanic construction, and has been largely unchanged since the Noachian.

  16. Degree variances of the earth's potential, topography and its isostatic compensation

    NASA Technical Reports Server (NTRS)

    Rapp, R. H.

    1982-01-01

    A spherical harmonic expansion of the earth's gravitational potential and equivalent rock topography to degree and order 180 is described. The potential implied by the topography considered as uncompensated and with isostatic compensation has been computed. Good agreement with the observed potential field is found when the depth of compensation in the Airy theory is assumed to be 50 km. At the higher degrees the correlation coefficient between the potential expansion and the equivalent rock topography is about 0.5. The Lachapelle equations for the topographic isostatic potential were tested using 1 x 1 deg equivalent rock topography. The degree variances agree at the lower degrees but at degree 36 the Lachapelle results using 5 deg data underestimate the potential degree variances by about one-third.

  17. High Resolution Global Topography of Itokawa from Hayabusa Imaging and LIDAR Data

    NASA Technical Reports Server (NTRS)

    Gaskell, Robert W.; Barnouin-Jha, O. S.; Scheeres, D. J.; Mukai, T.; Hirata, N.; Abe, S.; Saito, J.; Hashimoto, T.; Ishiguro, M.; Kubota, T.

    2006-01-01

    This viewgraph document reviews the topography of the Itokawa asteroid. It summarizes some of the relevant information about the asteroid, and how using the imaging from Hayabusa and LIDAR data, a topographic image of Itokawa was derived.

  18. Effect of near-surface topography on high-frequency Rayleigh-wave propagation

    NASA Astrophysics Data System (ADS)

    Wang, Limin; Xu, Yixian; Xia, Jianghai; Luo, Yinhe

    2015-05-01

    Rayleigh waves, which are formed due to interference of P- and Sv-waves near the free surface, propagate along the free surface and vanish exponentially in the vertical direction. Their propagation is strongly influenced by surface topography. Due to the high resolution and precision requirements of near-surface investigations, the high-frequency Rayleigh waves are usually used for near-surface structural detecting. Although there are some numerical studies on high-frequency Rayleigh-wave propagation on topographic free surface, detailed analysis of characters of high-frequency Rayleigh-wave propagation on topographic free surface remains untouched. Hence, research of propagation of Rayleigh waves on complex topographic surface becomes critical for Rayleigh-wave methods in near-surface applications. To study the propagation of high-frequency Rayleigh waves on topographic free surface, two main topographic models are designed in this study. One of the models contains a depressed topographic surface, and another contains an uplifted topographic surface. We numerically simulate the propagation of high-frequency Rayleigh waves on these two topographic surfaces by finite-difference method. Soon afterwards, we analyze the propagation character of high-frequency Rayleigh waves on such topographic models, and compare the variations on its energy and frequency before and after passing the topographic region. At last, we discuss the relationship between the variations and topographical steepness of each model. Our numerical results indicate that influence of depressed topography for high-frequency Rayleigh waves is more distinct than influence of uplifted topography. Rayleigh waves produce new scattering body waves during passing the depressed topography with reduction of amplitude and loss of high-frequency components. Moreover, the steeper the depressed topography is, the more energy of Rayleigh waves is lost. The uplifted topography with gentle slope produces similar influence as the depressed topography on propagation of high-frequency Rayleigh waves. When slopes are getting steep, however, the obstacle influence of the uplifted topography becomes weak. In addition, in the uplifted-topography case, part of Rayleigh-wave energy is absorbed by the uplifted terrain, which includes the trapped energy between the uplifted boundaries and the generation of scattering waves. Meanwhile, local topography strongly affects the character of Rayleigh-wave dispersion. Egregious error may be introduced, when pick Rayleigh-wave phase velocities on dispersion energy images for an MASW survey, if the local free-surface topography is ignored.

  19. The effect of selected parameters of the honing process on cylinder liner surface topography

    NASA Astrophysics Data System (ADS)

    Pawlus, P.; Dzierwa, A.; Michalski, J.; Reizer, R.; Wieczorowski, M.; Majchrowski, R.

    2014-04-01

    Many truck cylinder liners made from gray cast iron were machined. Ceramic and diamond honing stones were used in the last stages of operation: coarse honing and plateau honing. The effect of honing parameters on the cylinder liner surface topography was studied. Selected surface topography parameters were response variables. It was found that parameters from the Sq group were sensitive to honing parameter change. When plateau honing time varied, the Smq parameter increased, while the other parameters, Spq and Svq, were stable.

  20. The spectra of the topography of the earth, Venus, and Mars

    NASA Astrophysics Data System (ADS)

    Balmino, G.

    1993-06-01

    A spherical harmonic analysis is conducted for the topographies of the terrestrial planets using extant data sets to the highest possible degree and order, with a view to establishing the decay of such spectra over a larger range of frequencies and ascertain the limit of validity of the data sets employed. The shape of power spectra is confirmed for the cases of the earth and for Venus; Mars topography is still uncertain in many regions.

  1. High Resolution Topography Analysis on Threading Edge Dislocations in 4H-SiC Epilayers

    SciTech Connect

    Kamata, I.; Nagano, M; Tsuchida, H; Chen, Y; Dudley, M

    2009-01-01

    Threading edge dislocations (TEDs) in a 4H-SiC epitaxial layer are investigated using high-resolution synchrotron topography. Six types of TED image are confirmed to correspond to the Burgers vector directions by a comparison of computer simulated images and observed topography images in crystal boundaries. Using a mapping method, a wide spatial distribution of the six types of TED is examined in a quarter section of a 2-inch wafer.

  2. The Ocean Surface Topography JASON-CS/SENTINEL-6 Mission

    NASA Astrophysics Data System (ADS)

    Cullen, R.; Francis, R.

    2014-12-01

    The Jason-CS/Sentinel-6 programme will consist of 2 spacecraft and will be the latest in a series of ocean surface topography missions that will span nearly three decades. They follow the altimeters on-board TOPEX/Poseidon through to Jason-3 (expected March 2015). Jason-CS will continue to fulfil objectives of the reference series whilst introducing a major enhancement in capability providing the operational and science oceanographic community with the state of the art in terms of platform, measurement instrumentation design thus securing optimal operational and science data return. The programme is a part of the EC Copernicus initiative, whose objective is to support Europe's goals regarding sustainable development and global governance of the environment by providing timely and quality data, information, services and knowledge. The programme brings together: ESA for development, procurement & early orbit activities; EUMETSAT for mission management, ground segment, flight ops, contributing funding of the 1st satellite and participation in funding for the 2nd satellite; NOAA for US payload instruments, launcher, ground stations & operations; NASA for developing the US payload, launcher procurement and funding US science; EU for funding the operations and participation in funding (with EUMETSAT) for the 2nd satellite; CNES for mission expertise and provision of POD. The consortium plan to procure 2 satellites with the 1st planned for launch readiness in the 1st half of 2020 with the 2nd satellite 5 years later. The first major commitment to funding was given by the ESA member states that approved the programme in June 2014 and in addition the European Union funding is also secure. The design will be based on a platform derived from CryoSat-2 but adjusted to the specific requirements of the higher orbit. The principle payload instrument is a high precision Ku/C band radar altimeter with retrieval of geophysical parameters (surface elevation, wind speed and SWH) from the altimeter data require supporting measurements: a DORIS receiver for POD; The Climate Quality Advanced Microwave Radiometer (AMR-C) provided by JPL for high stability path delay correction. Orbit tracking data are also provided by GPS & LRA. An additional US GPS receiver, GNSS-RO, will be dedicated to radio-occultation measurements.

  3. Intraplate Seismicity, Oceanic Basement Topography and Marine Gravity

    NASA Astrophysics Data System (ADS)

    Gli, L.; Royer, J.-Y.; Goslin, J.; Dziak, R. D.

    2006-07-01

    The in traplate seismicity that affects the ocean seaf loor is poorly known, while it is of critical importance to understand th e thermal structur e of the oceanic lithospher e and assess th e pecularities - if any - of the earthquake g eneration processes in submarin e env ironmen ts. T-waves generated by submarine earthquak es can propagate almost w ithout attenuation in the SOFA R (Sound Fixing And Rang ing) channel, as f ar as a few thousands kilometers aw ay from th e epicenter. Hydrophones arrays have thus been recently used to detect small- magnitude earthquakes (Ms<3) that are undetectable or impr ecisely located by land-based seismolog ical n etworks, providing unpreceden ted data and new insights on the low-level seismicity of the oceanic lithosphere, over areas extend ing over a few millions squar e kilometers. However, to fu lly intr epret hydrophone arrays, it is necessary to recogn ize the tectonic environmen t near the ep icenter, using structural maps of the seafloor. Marine gr avity and bathymetry der ived from satellite altimetry ar e, to date, the only means to improve th is knowledg e at a global scale, esp ecially in th e r emotest areas of the world's ocean s,for at least two reasons : 1) deep seaf loor areas w ill not be exhaustively surveyed with shipboard mu ltibeam systems in a foreseeab le future ; 2) some ar eas, such as for instan ce,th e Centr al Indian O cean Basin, where a very active intrap late seismicity occurs, are thick ly cover ed with sediments. Marine gravity thus remains the only w ay to map the structure of the rough igneous at a b asin scale. Here, we pr esen t some examp les showing the benefit that would be gained by improving the resolution of satellite der ived models of mar ine gravity and bathymetry in deriv ing a detailed basement topography grid. Such a gr id would in turn represen t a most v alu able framework to study intrap late seismicity from the interpretation of hydrophone acoustic data. Th ese ex amples concern the study of : intrap late seismicity within the Indian Ocean through th e ION ETH Project intrap late seismicity within the North Atlantic Ocean seismic precursors prior to large earthquak es at ocean ic fr acture zones the rheology of the o ceanic lithosphere

  4. Topography within the axial channels of Monterey and Soquel Canyons

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    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 the AUV to fly through the sinuous canyons at 3 knots on a pre-programmed route while maintaining an altitude of 50 m above the bottom. The AUV has flown down through the sinuous canyons, passed where they join, to 1,900 m water depths, and obtained three or more overlapping swaths covering the axial channel floor and some of its adjacent flanks. One feature revealed in the multibeam bathymetry data are wave-like bedforms with wavelengths of 20 to 100 m and amplitudes up to 2.5 m oriented roughly perpendicular to the channel axis. These bedforms occur throughout the channel of Monterey Canyon. They are asymmetric with a steep face on the down-canyon side while the other face is nearly horizontal or dips up-canyon, and form crescent-shaped ridges oriented down-canyon. Combined with previous mapping of the upper end of Monterey Canyon by CSUMB, we now know that these features extend between 11 m and >1900 m water depths in Monterey Canyon. Repeat mapping shows that these bedforms change position between surveys. Sediment coring and experiments to track seafloor motion show that these changes occur during discrete mass transport events. In contrast the seafloor within the axis of Soquel Canyon is smooth. Chirp profiler data collected simultaneously with the multibeam data failed to resolve sub-bottom structures within the floor of Monterey Canyon, but show that the floor of Soquel Canyon contains up to15 m of horizontally layered fill. These differences are attributed to the processes within an active (e.g., Monterey) versus inactive (e.g., Soquel) submarine canyon and are hypothesized to be associated with the nature of the fill (cohesion-less sand and gravel versus cohesive fine sediments) within these canyons.

  5. The Impact of Drainage Reorganization on Cenozoic Topography

    NASA Astrophysics Data System (ADS)

    Yanites, B. J.; Ehlers, T. A.

    2011-12-01

    Landscape evolution and the resulting sedimentary deposits are controlled by the development and organization of drainage basins. As a landscape evolves within a climatic and tectonic environment, drainage reorganization events can occur, where one river basin grows at the expense of another. The added discharge downstream of a river capture location will generate a transient topographic response. The records of these events are preserved the sedimentary record and modern topography. Drainage reorganization has been proposed to occur in a number of major drainage systems around the world including the Colorado, Rhine, Snake, Yellow, Yangtze, Indus, and Zambezi rivers as well as a number of smaller rivers. Yet little work has focused on quantifying the topographic and erosional consequence of such events. Here we propose a simple model that quantifies the impacts of drainage capture on the evolution of a drainage basin. The model is based on the inverse slope-contributing drainage area relationship observed in rivers throughout the world and describes the expected river elevation change as drainage area is added (and therefore slopes lowered) by a capture event. Furthermore, we develop a numerical model of drainage capture that quantifies the transience of erosion and sediment production based on a shear stress dependent fluvial incision and sediment transport model. Our focus here is on quantifying the impact of capture of the Rhine/Aare river system (~45,000 km2) during the late Pliocene/early Pleistocene. Our models suggest 500-800 m of river elevation change (lowering profiles) occurred over short time periods (less than a million years), contributing as much as 0.4 mm/yr of erosion to the Alpine foreland and Swiss Alps when averaged over the last few million years. The predicted incision magnitudes are consistent with incision measured from the elevation of Pliocene and early Pleistocene river gravels, suggesting that the majority of incision across northern Switzerland can be explained by drainage reorganization. We also present estimates of incision magnitudes for other capture events around the world, and show that the erosion impacts of drainage reorganization events are capable of producing significant pulses of sediments out of the basin. This has implications for the interpretation of sedimentary deposits and their relation to tectonic and climatic changes.

  6. Gravity, Topography, and Magnetic Field of Mercury from Messenger

    NASA Technical Reports Server (NTRS)

    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

    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.

  7. Protein adsorption and cell adhesion on polyurethane/Pluronic surface with lotus leaf-like topography.

    PubMed

    Zheng, Jun; Song, Wei; Huang, He; Chen, Hong

    2010-06-01

    Lotus leaf-like polyurethane/Pluronic F-127 surface was fabricated via replica molding using a natural lotus leaf as the template. Water contact angle measurements showed that both the hydrophobicity of the unmodified polyurethane (PU) surface and the hydrophilicity of the PU/Pluronic surface were enhanced by the construction of lotus leaf-like topography. Protein adsorption on the PU/Pluronic surface without topographic modification was significantly lower than on the PU surface. Adsorption was further reduced when lotus leaf-like topography was constructed on the PU/Pluronic surface. Cell culture experiments with L929 cells showed that adhesion on the PU/Pluronic surface with lotus leaf-like topography was low and adherent cells were spherical and of low viability. The PU/Pluronic surface with lotus leaf-like topography thus appears to be resistant to nonspecific protein adsorption and to cell adhesion, and these effects derive from the both chemical composition and topography. The results suggest a new strategy based on surface topography for the design of antifouling materials. PMID:20172699

  8. 3D surface topography of cylinder liner forecasting during plateau honing process

    NASA Astrophysics Data System (ADS)

    Reizer, R.; Pawlus, P.

    2011-08-01

    Areal surface topographies after plateau honing process were measured. A correlation analysis of surface texture parameters was then carried out. As the results, the following parameters describing plateau honed cylinder 3D surface topography were selected: amplitude Sq, Sz, spatial: Str, Std, hybrid S?q as well as functional: Spq, Svq and Smq. 3D surface topographies were modeled. The modeled surface topographies were correctly matched to measured ones in 77% of all analyzed cases. The plateau honing experiment was then carried out using an orthogonal selective research plan. Two machining parameters were input variables: coarse honing pressure pv and plateau honing time t. Chosen cylinder liners texture parameters were output values. As the result of the experiment, regression equations connecting plateau honing process parameters pv and t with recommended 3D surface topography parameters were obtained. Finally, cylinder liner surface topographies were predicted for various values of machining parameters. Proper matching accuracy of modeled to measured textures was assured in 67% of analyzed cases.

  9. Spatial patterns in the evolution of Cenozoic dynamic topography and its influence on the Antarctic continent

    NASA Astrophysics Data System (ADS)

    Anderson, Lester; Ferraccioli, Fausto; Eagles, Graeme; Steinberger, Bernhard; Ritsema, Jeroen

    2013-04-01

    Our knowledge of dynamic topography in Antarctica remains in an infancy stage compared to other continents. We assess the space-time variability in dynamic topography in Antarctica by analysing grids of global dynamic topography in the Cenozoic (and late Cretaceous) based on the tomographic model S40RTS. Our model reveals that the Gamburtsev Province and Dronning Maud Land, two of the major nucleation sites for the East Antarctic Ice Sheet (EAIS) were ~500 m higher 60 Ma ago. The increased elevation may have facilitated ephemeral ice cap development in the early Cenozoic. Between ca 25 and 50 Ma the northern Wilkes Subglacial Basin was ca 200 m higher than today and a major increase in regional elevation (>600 m) occurred over the last 20-15 Ma over the northern and southern Victoria Land in the Transantarctic Mountains (TAM). The most prominent signal is observed over the Ross Sea Rift (RSR) where predicted Neogene dynamic topography exceeds 1,000 m. The flow of warm mantle from the West Antarctic Rift System (WARS)may have driven these dynamic topography effects over the TAM and RSR. However, we found that these effects are comparatively less significant over the Marie Byrd Land Dome and the interior of the WARS. If these contrasting dynamic topography effects are included, then the predicted elevations of the Ross Sea Embayment ca 20 Ma ago are more similar to the interior of the WARS, with significant implications for the early development of the West Antarctic Ice Sheet.

  10. High surface topography related to upper mantle flow beneath Eastern Anatolia

    NASA Astrophysics Data System (ADS)

    Komut, Tolga

    2015-11-01

    Eastern Anatolia region between north-south colliding Arabian and Eurasian plates has no significant crustal root and shallow (upper) mantle flow beneath seems to be vertically supporting its high topography. It has a high surface heat flow and the underlying mantle is characterized by low seismic velocity zones. Using a mantle density/temperature variation field derived from P-wave seismic velocity, current shallow mantle flow and resultant dynamic topography of Eastern Anatolia and adjacent Arabian foreland and Caucasus areas were calculated along a vertical section. The section crosses the tectonic boundaries interrelated with slab bodies (high seismic velocity/cold regions) and the low velocity zones above the slabs. According to the modelling experiments, the surface topography of Eastern Anatolia seems to be supported by shallow mantle flow dynamics. On the other hand, residual topography for the region was calculated using high resolution crustal thickness data. Positive residual topography that suggests an undercompensated state of Eastern Anatolia is in concordance with the dynamic topography anomaly. The modelled local shallow mantle flow support due to the density contrast between hot (low velocity) zones and underlying cold slab bodies beneath the area may be the present-day snapshot of the mantle flow uplift in Eastern Anatolia presence of which was previously suggested.

  11. Surface topography of hydroxyapatite promotes osteogenic differentiation of human bone marrow mesenchymal stem cells.

    PubMed

    Yang, Wanlei; Han, Weiqi; He, Wei; Li, Jianlei; Wang, Jirong; Feng, Haotian; Qian, Yu

    2016-03-01

    Effective and safe induction of osteogenic differentiation is one of the key elements of bone tissue engineering. Surface topography of scaffold materials was recently found to promote osteogenic differentiation. Utilization of this topography may be a safer approach than traditional induction by growth factors or chemicals. The aim of this study is to investigate the enhancement of osteogenic differentiation by surface topography and its mechanism of action. Hydroxyapatite (HA) discs with average roughness (Ra) of surface topography ranging from 0.2 to 1.65?m and mean distance between peaks (RSm) ranging from 89.7 to 18.6?m were prepared, and human bone-marrow mesenchymal stem cells (hBMSCs) were cultured on these discs. Optimal osteogenic differentiation was observed on discs with surface topography characterized by Ra ranging from 0.77 to 1.09?m and RSm ranging from 53.9 to 39.3?m. On this surface configuration of HA, hBMSCs showed oriented attachment, F-actin arrangement, and a peak in the expression of Yes-associated protein (YAP) and PDZ binding motif (TAZ) (YAP/TAZ). These results indicated that the surface topography of HA promoted osteogenic differentiation of hBMSCs, possibly by increasing cell attachment and promoting the YAP/TAZ signaling pathway. PMID:26706505

  12. Modeling of metallic surface topography modification by high-frequency vibration

    NASA Astrophysics Data System (ADS)

    Yao, Zhehe; Mei, Deqing; Chen, Zichen

    2016-02-01

    High-frequency vibration is capable of modifying metallic surface topography significantly, while the underlying mechanisms are still unclear. In this study, the acoustic softening effect is considered to explain and model the effects of high-frequency normal vibration on surface topography. The surface asperities can be softened by the high-frequency vibration due to acoustic softening, leading to the enhancement of surface topography modification. A theoretical model for metallic surface topography modification by high-frequency vibration is proposed based on the acoustic plasticity. Numerical predictions of surface roughness evolution were conducted under various working conditions based on the model developed. It was found that the reduction of surface roughness (RSR) after vibration-assisted forming was affected by static stress, vibration amplitude, material properties and initial specimen surface roughness. The predictions using the developed model were compared with experimental data. Results showed that the predicted RSR agreed well with the experimental results, indicating that the analytical model is able to accurately capture surface topography evolution during vibration-assisted metal forming. This study provides a basis for understanding the underlying mechanisms of surface topography modification in vibration-assisted manufacturing.

  13. SWOT, The Surface Water and Ocean Topography Satellite Mission (Invited)

    NASA Astrophysics Data System (ADS)

    Alsdorf, D.; Andreadis, K.; Bates, P. D.; Biancamaria, S.; Clark, E.; Durand, M. T.; Fu, L.; Lee, H.; Lettenmaier, D. P.; Mognard, N. M.; Moller, D.; Morrow, R. A.; Rodriguez, E.; Shum, C.

    2009-12-01

    Surface fresh water is essential for life, yet we have surprisingly poor knowledge of its variability in space and time. Similarly, ocean circulation fundamentally drives global climate variability, yet the ocean current and eddy field that affects ocean circulation and heat transport at the sub-mesoscale resolution and particularly near coastal and estuary regions, is poorly known. About 50% of the vertical exchange of water properties (nutrients, dissovled CO2, heat, etc) in the upper ocean is taking place at the sub-mesoscale. Measurements from the Surface Water and Ocean Topography satellite mission (SWOT) will make strides in understanding these processes and improving global ocean models for studying climate change. SWOT is a swath-based interferometric-altimeter designed to acquire elevations of ocean and terrestrial water surfaces at unprecedented spatial and temporal resolutions. The mission will provide measurements of storage changes in lakes, reservoirs, and wetlands as well as estimates of discharge in rivers. These measurements are important for global water and energy budgets, constraining hydrodynamic models of floods, carbon evasion through wetlands, and water management, especially in developing nations. Perhaps most importantly, SWOT measurements will provide a fundamental understanding of the spatial and temporal variations in global surface waters, which for many countries are the primary source of water. An on-going effort, the virtual mission (VM) is designed to help constrain the required height and slope accuracies, the spatial sampling (both pixels and orbital coverage), and the trade-offs in various temporal revisits. Example results include the following: (1) Ensemble Kalman filtering of VM simulations recover water depth and discharge, reducing the discharge RMSE from 23.2% to 10.0% over an 84-day simulation period, relative to a simulation without assimilation. (2) Ensemble-based data assimilation of SWOT like measurements yields bathymetric slope and depth to within 3.0 microradians and 50 cm, respectively. (3) SWOT measurements of storage changes in lakes larger than 1 km2 will have relative errors generally less than 5% whereas errors for one-hectare size lakes will be about 20%. (4) SWOT estimates of discharge compared to a one-year model-based truth data set suggest that instantaneous discharge estimates will have a median relative RMSE of 10.9% and that 86% of all instantaneous errors will be less than 25%. (5) Based on a global distribution of gauge-based discharge and candidate SWOT orbits with varying spatial and temporal sampling, SWOT errors in instantaneous discharge will be less than 25% for rivers wider than 50 m, whereas errors in monthly discharge will be less than 20% for rivers with drainage areas larger than 7000 km2. (6) We estimate that currently available satellite nadir altimetry data cannot monitor more than 15% of the global lake volume variation, whereas from 50% to more than 65% of the global lake volume variation will be observed by SWOT.

  14. Estimating Vegetation Height and Bare-Earth Topography from SRTM Data using Fourier Spectral Decomposition

    NASA Astrophysics Data System (ADS)

    Gangodagamage, C.; Liu, D.; Alsdorf, D.

    2010-12-01

    In this study, LiDAR vegetation topography (bare-earth + vegetation height), LiDAR bare-earth topography, the National Elevation Data (NED) set, and Shuttle Radar Terrain Mission (SRTM) measurements are used to develop a statistical model to explore the possibility of extracting vegetation height measurements and accurate high resolution bare-earth topography from SRTM data. The key innovation is to obtain the statistical signature of the vegetation height measurements in the Fourier domain by taking advantage of the well-known linearity in additive properties of the Fourier transform. We demonstrate that the power-law relationship, P(k) α k^(-β), as shown by the bare-earth topography, breaks down approximately at a cross-over wavenumber, k=k_c, due to the vegetation height effect using four different topographic and vegetation study locations in the United States. We document that the vegetation effect mainly dominates the high-frequency contents of the vegetation topography from 2-180 m, 1-60 m, and 1-70 m for the South Fork Eel River, California; Flathead Lake, Montana; and Tenderfoot Creek, Montana, LiDAR data, respectively, and from 1-240 m for 30 m SRTM data for the Jesup, Georgia site. Finally, we demonstrate our ability to obtain a high resolution bare-earth topography with RMSE of 9.6 m, 2.2 m, and 2.9 m and vegetation height with RMSE of 11.0 m (11% error), 4.5 m (12% error), and 1.6 m (8% error) for LiDAR data study sites, whereas for the SRTM data, bare-earth topography and vegetation height are obtained with RMSE values of 5.4 m and 3.1 m, respectively, for the Jesup site. Model Vegetation height

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  16. Analysis of high-throughput screening reveals the effect of surface topographies on cellular morphology.

    PubMed

    Hulsman, Marc; Hulshof, Frits; Unadkat, Hemant; Papenburg, Bernke J; Stamatialis, Dimitrios F; Truckenmller, Roman; van Blitterswijk, Clemens; de Boer, Jan; Reinders, Marcel J T

    2015-03-01

    Surface topographies of materials considerably impact cellular behavior as they have been shown to affect cell growth, provide cell guidance, and even induce cell differentiation. Consequently, for successful application in tissue engineering, the contact interface of biomaterials needs to be optimized to induce the required cell behavior. However, a rational design of biomaterial surfaces is severely hampered because knowledge is lacking on the underlying biological mechanisms. Therefore, we previously developed a high-throughput screening device (TopoChip) that measures cell responses to large libraries of parameterized topographical material surfaces. Here, we introduce a computational analysis of high-throughput materiome data to capture the relationship between the surface topographies of materials and cellular morphology. We apply robust statistical techniques to find surface topographies that best promote a certain specified cellular response. By augmenting surface screening with data-driven modeling, we determine which properties of the surface topographies influence the morphological properties of the cells. With this information, we build models that predict the cellular response to surface topographies that have not yet been measured. We analyze cellular morphology on 2176 surfaces, and find that the surface topography significantly affects various cellular properties, including the roundness and size of the nucleus, as well as the perimeter and orientation of the cells. Our learned models capture and accurately predict these relationships and reveal a spectrum of topographies that induce various levels of cellular morphologies. Taken together, this novel approach of high-throughput screening of materials and subsequent analysis opens up possibilities for a rational design of biomaterial surfaces. PMID:25554402

  17. A consistent data set of Antarctic ice sheet topography, cavity geometry, and global bathymetry

    NASA Astrophysics Data System (ADS)

    Timmermann, R.; Le Brocq, A.; Deen, T.; Domack, E.; Dutrieux, P.; Galton-Fenzi, B.; Hellmer, H.; Humbert, A.; Jansen, D.; Jenkins, A.; Lambrecht, A.; Makinson, K.; Niederjasper, F.; Nitsche, F.; Nøst, O. A.; Smedsrud, L. H.; Smith, W. H. F.

    2010-12-01

    Sub-ice shelf circulation and freezing/melting rates in ocean general circulation models depend critically on an accurate and consistent representation of cavity geometry. Existing global or pan-Antarctic topography data sets have turned out to contain various inconsistencies and inaccuracies. The goal of this work is to compile independent regional surveys and maps into a global data set. We use the S-2004 global 1-min bathymetry as the backbone and add an improved version of the BEDMAP topography (ALBMAP bedrock topography) for an area that roughly coincides with the Antarctic continental shelf. The position of the merging line is individually chosen in different sectors in order to capture the best of both data sets. High-resolution gridded data for ice shelf topography and cavity geometry of the Amery, Fimbul, Filchner-Ronne, Larsen C and George VI Ice Shelves, and for Pine Island Glacier are carefully merged into the ambient ice and ocean topographies. Multibeam survey data for bathymetry in the former Larsen B cavity and the southeastern Bellingshausen Sea have been obtained from the data centers of Alfred Wegener Institute (AWI), British Antarctic Survey (BAS) and Lamont-Doherty Earth Observatory (LDEO), gridded, and blended into the existing bathymetry map. The resulting global 1-min Refined Topography data set (RTopo-1) contains self-consistent maps for upper and lower ice surface heights, bedrock topography, and surface type (open ocean, grounded ice, floating ice, bare land surface). The data set is available in NetCDF format from the PANGAEA database at doi:10.1594/pangaea.741917.

  18. Geoid Anomalies and Dynamic Topography from Time Dependent, Spherical Axisymmetric Mantle Convection

    NASA Technical Reports Server (NTRS)

    Kiefer, Walter S.; Kellogg, Louise H.

    1998-01-01

    Geoid anomalies and dynamic topography are two important diagnostics of mantle convection. We present geoid and topography results for several time-dependent convection models in spherical axisymmetric geometry for Rayleigh numbers between 10(exp 6) and 10(exp 7) with depth-dependent viscosity and mixtures of bottom and internal heating. The models are strongly chaotic, with boundary layer instabilities erupting out of both thermal boundary layers. In some instances, instabilities from one boundary layer influence the development of instabilities in the other boundary layer. Such coupling between events at the top and bottom of the mantle has been suggested to play a role in a mid-Cretaceous episode of enhanced volcanism in the Pacific. These boundary layer instabilities produce large temporal variations in the geoid anomalies and dynamic nd to the topography associated with the convection. The amplitudes of these fluctuations depend on the detailed model parameter,.% it of this but fluctuations of 30-50% relative to the time-averaged geoid and topography are common. The convective planform is strongly sensitive to the specific initial conditions. Convection cells with larger aspect ratio tend to have larger fractional fluctuations in their geoid and topography amplitudes, because boundary layer instabilities have more time to develop in long cells. In some instances, we observe low-amplitude topographic highs adjacent to the topographic lows produced by cold downwellings. We discuss applications of these results to several situations, including the temporal variability of m basis. hotspots such as Hawaii, the topography of subduction zone outer rises, and the topography of coronae on Venus.

  19. Effect of the Earth's surface topography on quasi-dynamic earthquake cycles

    NASA Astrophysics Data System (ADS)

    Ohtani, Makiko; Hirahara, Kazuro

    2015-10-01

    We take account of the effect of Earth's surface topography in quasi-dynamic earthquake cycle simulations using a boundary integral equation method. While we have so far assumed a homogeneous elastic half-space medium with a flat free surface, Earth's actual surface topography is complicated. Here, we constructed new slip response functions in half-space with an arbitrarily shaped surface topography in which we used slip response functions in full-space by introducing imaginary free surface cells in addition to embedded fault ones. By comparing analytical slip response functions in the case of a flat surface overlying half-space with the new ones, we developed a computationally efficient method for setting the Earth's surface region, which was divided into cells with the appropriate sizes depending on the fault source cell depth to maintain the computational accuracy. With these new slip response functions, we simulated simple interplate earthquake cycles in the region close to the Japan Trench, off Miyagi, Tohoku, in northeast Japan, which has the amplitude of 7 km in depth. Compared with the case where the flat surface level was set at the trench depth, the slip response functions for the case where actual seafloor topography was used had smaller amplitudes. Hence, the actual topography produces smaller recurrence times for earthquake cycles than that for the flat surface case. These effects of the actual Earth's surface topography mainly come from changes in the distance between the surface and the fault compared with the flat surface case. Changes in the slip response function also represent changes in the fault stiffness of the system. Considering the actual topography of the Earth's surface to be convex upwards as opposed to the flat, the fault stiffness becomes larger compared to the case of the flat Earth's surface. This leads to a change in the frictional instability, and sometime leads to the change in the way of rupture.

  20. The Laser Vegetation Imaging Sensor (LVIS): An Airborne Laser Altimeter for Mapping Vegetation and Topography

    NASA Technical Reports Server (NTRS)

    Bryan, J.; Rabine, David L.

    1998-01-01

    The Laser Vegetation Imaging Sensor (LVIS) is an airborne laser altimeter designed to quickly and extensively map surface topography as well as the relative heights of other reflecting surfaces within the laser footprint. Since 1997, this instrument has primarily been used as the airborne simulator for the Vegetation Canopy Lidar (VCL) mission, a spaceborne mission designed to measure tree height, vertical structure and ground topography (including sub-canopy topography). LVIS is capable of operating from 500 m to 10 km above ground level with footprint sizes from 1 to 60 m. Laser footprints can be randomly spaced within the 7 degree telescope field-of-view, constrained only by the operating frequency of the ND:YAG Q-switched laser (500 Hz). A significant innovation of the LVIS altimeter is that all ranging, waveform recording, and range gating are performed using a single digitizer, clock base, and detector. A portion of the outgoing laser pulse is fiber-optically fed into the detector used to collect the return signal and this entire time history of the outgoing and return pulses is digitized at 500 Msamp/sec. The ground return is then located using software digital signal processing, even in the presence of visibly opaque clouds. The surface height distribution of all reflecting surfaces within the laser footprint can be determined, for example, tree height and ground elevation. To date, the LVIS system has been used to monitor topographic change at Long Valley caldera, CA, as part of NASA's Topography and Surface Change program, and to map tree structure and sub-canopy topography at the La Selva Biological Research Station in Costa Rica, as part of the pre-launch calibration activities for the VCL mission. We present results that show the laser altimeter consistently and accurately maps surface topography, including sub-canopy topography, and vegetation height and structure. These results confirm the measurement concept of VCL and highlight the benefits of airborne prototypes of spaceborne instruments.

  1. Molecular response of Escherichia coli adhering onto nanoscale topography

    NASA Astrophysics Data System (ADS)

    Rizzello, Loris; Galeone, Antonio; Vecchio, Giuseppe; Brunetti, Virgilio; Sabella, Stefania; Pompa, Pier Paolo

    2012-10-01

    Bacterial adhesion onto abiotic surfaces is an important issue in biology and medicine since understanding the bases of such interaction represents a crucial aspect in the design of safe implant devices with intrinsic antibacterial characteristics. In this framework, we investigated the effects of nanostructured metal substrates on Escherichia coli adhesion and adaptation in order to understand the bio-molecular dynamics ruling the interactions at the interface. In particular, we show how highly controlled nanostructured gold substrates impact the bacterial behavior in terms of morphological changes and lead to modifications in the expression profile of several genes, which are crucially involved in the stress response and fimbrial synthesis. These results mainly demonstrate that E. coli cells are able to sense even slight changes in surface nanotopography and to actively respond by activating stress-related pathways. At the same time, our findings highlight the possibility of designing nanoengineered substrates able to trigger specific bio-molecular effects, thus opening the perspective of smartly tuning bacterial behavior by biomaterial design.

  2. Numerical studies on the structure of Venusian mantle convection constrained by the geoid and topography

    NASA Astrophysics Data System (ADS)

    Yang, A.; Huang, J.; Zhong, S.

    2012-12-01

    Venus is a planet very similar to the Earth in terms of size, density and composition. However, different from the Earth which has active plate tectonics, Venus is a one-plate planet covered by a thick immobile lithosphere. Observations show that there may be nine hotspots on Venus and they may be still active. The topography and geoid of Venus have relatively long wavelength character with the degree 3 terms are the highest. Analysis about the geoid and topography of Venus shows that their correlation is high and the admittance ratio at lower degrees is large, suggesting a mainly dynamic origin for the topography and geoid at lower degrees. Using these results above as the main constraints, we systematically investigated the influence of phase transitions on the structure of Venusian mantle convection in 3D spherical shell. Both mantle phase transitions from olivine to spinel and from spinel to perovskite are included in our model. We employed an extended Boussinesq approximation, an infinite Prandtl number assumption and strongly temperature- and pressure-dependent viscosity in our model. Calculations are performed with the finite element code CitcomS. Numerical simulations show that convective structure is affected significantly by phase changes. The amplitude of the Clapeyron slops of phase changes and Rayleigh number control the dominant convective wavelength. When no phase changes are included in the model, a representative convective structure shows dominant short-wavelengths with numerous of plumes, typical of stagnant-lid convection. The geoid and the surface topography are highly correlated with large admittance at lower degrees and the powers of the topography and geoid spectra are significantly reduced at long-wavelengths compared with the observed. Phase changes could promote long-wavelength convective structures as previous findings. When other parameters are kept the same, increasing the Clapeyron slops of the phase changes will increase the powers of the topography and geoid spectra at the lower degrees and decrease the number of plumes. The increase of Rayleigh number will also increase the powers of the topography and geoid spectra at the lower degrees, but it will decrease the powers of the topography and geoid spectra at the relatively higher degrees. All these cases have Venus like large admittance ratio at lower degrees and high correlation for the topography and geoid. The model parameters that most satisfy Venus' observations are with a Rayleigh number of 210^8 and Clapeyron slops of +-3.5 MPa/K, which generally satisfy the number of plumes, the geoid amplitude spectra, and the admittance and correlation of Venus. The lithosphere is about 256 Km and the lower mantle viscosity is about 210^21 Pa.s.

  3. Integrated approach to estimate the ocean's time variable dynamic topography including its covariance matrix

    NASA Astrophysics Data System (ADS)

    Müller, Silvia; Brockmann, Jan Martin; Schuh, Wolf-Dieter

    2015-04-01

    The ocean's dynamic topography as the difference between the sea surface and the geoid reflects many characteristics of the general ocean circulation. Consequently, it provides valuable information for evaluating or tuning ocean circulation models. The sea surface is directly observed by satellite radar altimetry while the geoid cannot be observed directly. The satellite-based gravity field determination requires different measurement principles (satellite-to-satellite tracking (e.g. GRACE), satellite-gravity-gradiometry (GOCE)). In addition, hydrographic measurements (salinity, temperature and pressure; near-surface velocities) provide information on the dynamic topography. The observation types have different representations and spatial as well as temporal resolutions. Therefore, the determination of the dynamic topography is not straightforward. Furthermore, the integration of the dynamic topography into ocean circulation models requires not only the dynamic topography itself but also its inverse covariance matrix on the ocean model grid. We developed a rigorous combination method in which the dynamic topography is parameterized in space as well as in time. The altimetric sea surface heights are expressed as a sum of geoid heights represented in terms of spherical harmonics and the dynamic topography parameterized by a finite element method which can be directly related to the particular ocean model grid. Besides the difficult task of combining altimetry data with a gravity field model, a major aspect is the consistent combination of satellite data and in-situ observations. The particular characteristics and the signal content of the different observations must be adequately considered requiring the introduction of auxiliary parameters. Within our model the individual observation groups are combined in terms of normal equations considering their full covariance information; i.e. a rigorous variance/covariance propagation from the original measurements to the final product is accomplished. In conclusion, the developed integrated approach allows for estimating the dynamic topography and its inverse covariance matrix on arbitrary grids in space and time. The inverse covariance matrix contains the appropriate weights for model-data misfits in least-squares ocean model inversions. The focus of this study is on the North Atlantic Ocean. We will present the conceptual design and dynamic topography estimates based on time variable data from seven satellite altimeter missions (Jason-1, Jason-2, Topex/Poseidon, Envisat, ERS-2, GFO, Cryosat2) in combination with the latest GOCE gravity field model and in-situ data from the Argo floats and near-surface drifting buoys.

  4. How to approximate viscoelastic dynamic topographies of stagnant lid planetary bodies?

    NASA Astrophysics Data System (ADS)

    Dumoulin, Ca