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Sample records for topography gmrt synthesis

  1. 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

  2. Development of RESTful services and map-based user interface tools for access to the Global Multi-Resolution Topography (GMRT) Synthesis

    NASA Astrophysics Data System (ADS)

    Ferrini, V. L.; Morton, J. J.; Barg, B.

    2015-12-01

    The Global Multi-Resolution Topography (GMRT, http://gmrt.marine-geo.org) synthesis is a multi-resolution compilation of quality controlled multibeam sonar data, collected by scientists and institutions worldwide, that is merged with gridded terrestrial and marine elevation data. The multi-resolutional elevation components of GMRT are delivered to the user through a variety of interfaces as both images and grids. The GMRT provides quantitative access to gridded data and images to the full native resolution of the sonar as well as attribution information and access to source data files. To construct the GMRT, multibeam sonar data are evaluated, cleaned and gridded by the MGDS Team and are then merged with gridded global and regional elevation data that are available at a variety of scales from 1km resolution to sub-meter resolution. As of June 2015, GMRT included processed swath data from nearly 850 research cruises with over 2.7 million ship-track miles of coverage. Several new services were developed over the past year to improve access to the GMRT Synthesis. In addition to our long-standing Web Map Services, we now offer RESTful services to provide programmatic access to gridded data in standard formats including ArcASCII, GeoTIFF, COARDS/CF-compliant NetCDF, and GMT NetCDF, as well as access to custom images of the GMRT in JPEG format. An attribution metadata XML service was also developed to return all relevant information about component data in an area, including cruise names, multibeam file names, and gridded data components. These new services are compliant with the EarthCube GeoWS Building Blocks specifications. Supplemental services include the release of data processing reports for each cruise included in the GMRT and data querying services that return elevation values at a point and great circle arc profiles using the highest available resolution data. Our new and improved map-based web application, GMRT MapTool, provides user access to the GMRT

  3. A 50 MHz System for GMRT

    NASA Astrophysics Data System (ADS)

    Udaya Shankar, N.; Dwarakanath, K. S.; Amiri, S.; Somashekar, R.; Girish, B. S.; Laus, W.; Nayak, A.

    2009-09-01

    This paper describes a 50~MHz system being developed for GMRT to provide imaging capability in the frequency range 30-90~MHz. Due to its larger collecting area and higher antenna efficiency, the low-frequency GMRT system will be several times more sensitive than the present 74~MHz VLA system and is likely to remain a competitive instrument in this frequency band. In the first phase of this project, receiver systems consisting of V-dipole feeds and front-ends have been installed on four of the thirty GMRT antennas. Test observations were carried out on a number of bright 3CR sources. The initial results are encouraging. This paper will also describe results of simultaneous observations carried out using the existing GMRT correlator, the new GMRT software correlator and a system employing digitization and direct recording of signals at two antenna bases.

  4. Studies of novae at GMRT frequencies

    NASA Astrophysics Data System (ADS)

    Kantharia, N. G.

    2012-09-01

    The Giant Metrewave Radio Telescope (GMRT) which operates at wavelengths longer than 20 cm (frequencies ≤ 1.4 GHz) has been used to search for radio emission from Galactic novae systems since 2002. Of the 11 Galactic novae observed with GMRT, radio continuum emission has been detected in two of the systems whereas atomic gas associated with two systems has been imaged and studied in the 21 cm signal of H I. The two novae studied in the radio continuum with the GMRT are the remnant of GK Persei, a classical nova which had an outburst in 1901 and RS Ophiuchi, a recurrent nova following its last outburst in 2006. Combining the GMRT data on the classical nova GK Persei with VLA data at earlier epochs resulted in concluding that the nova remnant was undergoing a secular decrease in its flux density and in its adiabatic phase of evolution tep{2005A&A...435..167A}. RS Ophiuchi was observed at 1280, 610, 325 and 240 MHz with the GMRT days after its outburst and detected at all the observed frequencies. The near-simultaneous monitoring of its flux density at the low GMRT frequencies, resulted in the study of its spectral index which was indicative of synchrotron emission at all epochs tep{2007ApJ...667L.171K}. A supernova model resulted in a reasonable fit to the observed light curves; in particular the late appearance of emission at the lower GMRT frequencies due to the foreground clumpy, ionized, thermal circumbinary material. Comparison of these results with the previous outburst indicated that the densities of this clumpy medium had reduced making it optically thin to GMRT frequencies in 2006 tep{2007ApJ...667L.171K}. It is important to complement the higher radio frequency studies with observations at GMRT frequencies since these study different regions and physics of the nova system. Studies at GMRT frequencies can result in insights on the shock physics, distribution and density of the circumbinary material or planetary nebula, magnetic field generation and the

  5. GMRT observations of SN 2016bkv

    NASA Astrophysics Data System (ADS)

    Chandra, Poonam; Nayana, A. J.

    2016-04-01

    We observed SN 2016bkv, discovered by K. Itagaki (https://wis-tns.weizmann.ac.il//object/2016bkv) on 2016 March 21.70 UT, with the Giant Metrewave Radio Telescope (GMRT) on 2016 April 03.53 UT in 1390 MHz band.

  6. Radio emission from magnetic exoplanets: GMRT observations and results

    NASA Astrophysics Data System (ADS)

    Majid, W.; Winterhalter, D.; Kuiper, T.; Lazio, J.

    2011-10-01

    Massive extrasolar planets are expected to emit, in analogy with Jupiter and Saturn, detectable radio emission at low frequencies. We have carried out a series of observations of known extrasolar planetary systems at 150 MHz with the Giant Meterwave Radio Telescope (GMRT) in both interferometric and phased array modes. We will describe our observing campaign, target list, and preliminary results from studies of dynamic spectra. As low frequency observations are plagued with RFI, we will focus on observing strategies and analysis techniques to minimize, identify and remove RFI effects from dynamic spectra. We will also briefly discuss prospects for similar searches with future instruments such as LOFAR, the LWA, and the SKA instruments.

  7. 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.

  8. GMRT HI study of giant low surface brightness galaxies

    NASA Astrophysics Data System (ADS)

    Mishra, Alka; Kantharia, N. G.; Das, M.; Omar, A.; Srivastava, D. C.

    2016-10-01

    We present HI observations of four giant low surface brightness (GLSB) galaxies UGC 1378, UGC 1922, UGC 4422 and UM 163 using the Giant Meterwave Radio Telescope (GMRT). We include HI results on UGC 2936, UGC 6614 and Malin 2 from literature. HI is detected from all the galaxies and the extent is roughly twice the optical size; in UM 163, HI is detected along a broken disk encircling the optical galaxy. We combine our results with those in literature to further understand these systems. The main results are the following: (1) The peak HI surface densities in GLSB galaxies are several times 1021 cm-2. The HI mass is between 0.3 - 4 × 1010 M⊙, dynamical mass ranges from a few times 1011 M⊙ to a few times 1012 M⊙. (2) The rotation curves of GLSB galaxies are flat to the outermost measured point with rotation velocities of the seven GLSB galaxies being between 225 and 432 km s-1. (3) Recent star formation traced by near-ultraviolet emission in five GLSB galaxies in our sample appears to be located in rings around the galaxy centre. We suggest that this could be due to a stochastic burst of star formation at one location in the galaxy being propagated along a ring over a rotation period. (4) The HI is correlated with recent star formation in five of the seven GLSB galaxies.

  9. 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

  10. 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.

  11. 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.

  12. 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

  13. GMRT discovery of a 1.69 ms radio pulsar associated with XSS J12270-4859

    NASA Astrophysics Data System (ADS)

    Roy, J.; Bhattacharyya, B.; Ray, P. S.

    2014-02-01

    Following the reported state change observed in the low-mass X-ray binary XSS J12270-4859 (ATel #5647; Bassa et al. 2014, arXiv:1402.0765), we were granted Director's Discretionary Time to search for radio pulsations using the GMRT. We observed at 607 MHz with the GMRT coherent phased-array mode utilizing 70% of the array resulting in a beam width of 30 arcsec. We recorded 3 scans, each of 1-hour beginning on 2014 Feb 12 at 20:46:15 UTC, producing filter-bank outputs of 512 x 0.0651 MHz sampled at 61.44 microsec.

  14. A GMRT survey of regions towards the Taurus molecular cloud at 323 and 608 MHz

    NASA Astrophysics Data System (ADS)

    Ainsworth, Rachael E.; Coughlan, Colm P.; Green, David A.; Scaife, Anna M. M.; Ray, Tom P.

    2016-11-01

    We present observations of three active sites of star formation in the Taurus molecular cloud complex taken at 323 and 608 MHz (90 and 50 cm, respectively) with the Giant Metrewave Radio Telescope (GMRT). Three pointings were observed as part of a pathfinder project, targeted at the young stellar objects (YSOs) L1551 IRS 5, T Tau and DG Tau (the results for these target sources were presented in a previous paper). In this paper, we search for other YSOs and present a survey comprising of all three fields; a by-product of the large instantaneous field of view of the GMRT. The resolution of the survey is of order 10 arcsec and the best rms noise at the centre of each pointing is of order 100 μJy beam-1 at 323 MHz and 50 μJy beam-1 at 608 MHz. We present a catalogue of 1815 and 687 field sources detected above 5σrms at 323 and 608 MHz, respectively. A total of 440 sources were detected at both frequencies, corresponding to a total unique source count of 2062 sources. We compare the results with previous surveys and showcase a sample of extended extragalactic objects. Although no further YSOs were detected in addition to the target YSOs based on our source-finding criteria, these data can be useful for targeted manual searches, studies of radio galaxies or to assist in the calibration of future observations with the Low-Frequency Array towards these regions.

  15. Known Pulsars Identified in the GMRT 150 MHz All-sky Survey

    NASA Astrophysics Data System (ADS)

    Frail, D. A.; Jagannathan, P.; Mooley, K. P.; Intema, H. T.

    2016-10-01

    We have used the 150 MHz radio continuum survey (TGSS ADR) from the Giant Metrewave Radio Telescope (GMRT) to search for phase-averaged emission toward all well-localized radio pulsars north of -53° decl. We detect emission toward 200 pulsars with high confidence (≥slant 5σ ) and another 88 pulsars at fainter levels. We show that most of our identifications are likely from pulsars, except for a small number where the measured flux density is confused by an associated supernova or pulsar-wind nebula, or a globular cluster. We investigate the radio properties of the 150 MHz sample and find an unusually high number of gamma-ray binary millisecond pulsars with very steep spectral indices. We also note a discrepancy in the measured flux densities between GMRT and LOFAR pulsar samples, suggesting that the flux density scale for the LOFAR pulsar sample may be in error by approximately a factor of two. We carry out a separate search of 30 well-localized gamma-ray, radio-quiet pulsars in an effort to detect a widening of the radio beam into the line of sight at lower frequencies. No steep-spectrum emission was detected either toward individual pulsars or in a weighted stack of all 30 images.

  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 γ-ray source HESS J1818-154. With the goal of getting a complete view of this remnant and understanding the nature of the γ-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 α = -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. AGN Feedback in Galaxy Groups: A Joint GMRT/X-ray Study

    NASA Astrophysics Data System (ADS)

    Giacintucci, S.; Vrtilek, J. M.; O'Sullivan, E.; Raychaudhury, S.; David, L. P.; Venturi, T.; Athreya, R.; Gitti, M.

    2009-12-01

    We present an ongoing study of 18 nearby galaxy groups, chosen for the availability of Chandra and/or XMM-Newton data and evidence for AGN/hot intragroup gas interaction. We have obtained 235 and 610 MHz observations at the GMRT for all the groups, and 327 and 150 MHz for a few. We discuss two interesting cases-NGC 5044 and AWM 4-which exhibit different kinds of AGN/hot gas interaction. With the help of these examples we show how joining low-frequency radio data (to track the history of AGN outbursts through emission from aged electron populations) with X-ray data (to determine the state of hot gas, its disturbances, heating and cooling) can provide a unique insight into the nature of the feedback mechanism in galaxy groups.

  18. 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 Δν at the angular multipole ℓ, or equivalently the multi-frequency angular power spectrum Cℓ(Δν). An earlier measurement of Cℓ(Δν) using these data had revealed the presence of oscillatory patterns along Δν, 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 ℓ for which there is a dense sampling of the u-v plane. For three angular multipoles ℓ= 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 3σ 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.

  19. 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

  20. The investigation of short-term variations of Jupiter's Synchrotron Radiation with the large radio interferometer GMRT

    NASA Astrophysics Data System (ADS)

    Imai, Kota; Misawa, Hiroaki; Bhardwaj, Anil; Tsuchiya, Fuminori; Doi, Akihiro; Kondo, Tetsuro; Morioka, Akira

    initiated by solar UV flux enhancement and scattering of the JRB particles toward the polar region by whistler-mode wave, although it is still not known whether solar UV flux or whistler-mode wave is a dominant initiator. In order to investigate physical processes of short term variations, we observed JSR with the Giant Metrewave Radio Telescope (GMRT) from 23rd May 2007 to 27th June 2007. Bhardwaj et al. (2005) first made JSR observations with the GMRT for about a week in 2003 and suggested that JSR flux increased with Solar 10.7cm radio flux (F10.7), which is correlated to solar UV flux. On the other hand, the initial results of GMRT observation in 2007 show that the total flux of JSR varies in several days but is not strongly correlated to F10.7. Then, when the total flux of JSR increased, the peak position of JSR moved outward, and the flux of JSR increased in the outer emitting region. It is implied that the other acceleration processes cause these variations except the enhanced radial diffusion, because enhanced radial diffusion increases the flux of JSR and the peak position of JSR moves toward Jupiter. In this presentation, we will discuss the variations of JSR spatial distribution shown in the 2007 GMRT observation results. Acknowledgement: We would like to appreciate helpful support of Ishwara Chandra C. H. And, we thank the staff of the GMRT who have made these observations possible. GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research.

  1. 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

  2. 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.

  3. Derivation of Model Topography

    NASA Technical Reports Server (NTRS)

    Balgovind, R. C.

    1985-01-01

    The Fourth-Order model necessitates representation of the topography. The problem of the representation of the topography at grid points is addressed. The attempted was to derive an envelope topography. The TI is obtained by taking local mean plus one standard deviation at each grid point and sigma filtering it. The method was greatly influenced by large standard deviations at steep mountains. The O1 topography is the local mean. The S1 is obtained by Sigma filtering in both latitude and longitude the mean O1. The S2 is when the operation is applied twice and S3 thrice, the Q3 is the sigma filtered local mean of the upper third quantile of the source data.

  4. Geomorphology: Tales of topography

    NASA Astrophysics Data System (ADS)

    Flowers, Rebecca M.

    2014-07-01

    The origins of topographic relief are challenging to disentangle. Modelling shows that differential isostatic rebound due to erosion of rocks of variable density may influence topography, inspiring a fresh look at topographic highs in landscapes.

  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. Moire topography in odontology

    NASA Astrophysics Data System (ADS)

    Moreno Yeras, A.

    2001-08-01

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

  7. Photogrammetric portrayal of Mars topography.

    USGS Publications Warehouse

    Wu, S.S.C.

    1979-01-01

    Special photogrammetric techniques have been developed to portray Mars topography, using Mariner and Viking imaging and nonimaging topographic information and earth-based radar data. Topography is represented by the compilation of maps at three scales: global, intermediate, and very large scale. The global map is a synthesis of topographic information obtained from Mariner 9 and earth-based radar, compiled at a scale of 1:25,000,000 with a contour interval of 1 km; it gives a broad quantitative view of the planet. At intermediate scales, Viking Orbiter photographs of various resolutions are used to compile detailed contour maps of a broad spectrum of prominent geologic features; a contour interval as small as 20 m has been obtained from very high resolution orbital photography. Imagery from the Viking lander facsimile cameras permits construction of detailed, very large scale (1:10) topographic maps of the terrain surrounding the two landers; these maps have a contour interval of 1 cm. This paper presents several new detailed topographic maps of Mars.-Author

  8. 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

  9. Universal multifractal Martian topography

    NASA Astrophysics Data System (ADS)

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

    2015-07-01

    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 is 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 an other, excluding a general description at the planetary scale. In this article, we are analyzing 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 laser altimeter MOLA at 300 m horizontal resolution, 1 m vertical resolution. We adapted the Haar fluctuation method to the the irregularly sampled signal. The results suggest a multifractal behavior from planetary scale down to 10 km. From 10 km 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.

  10. 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.

  11. Investigation of the solar UV/EUV heating effect on the Jovian radiation belt by GMRT-IRTF observation

    NASA Astrophysics Data System (ADS)

    Kita, H.; Misawa, H.; Bhardwaj, A.; Tsuchiya, F.; Tao, C.; Uno, T.; Kondo, T.; Morioka, A.

    2012-12-01

    Jupiter's synchrotron radiation (JSR) is the emission from relativistic electrons, and it is the most effective probe for remote sensing of Jupiter's radiation belt from the Earth. Recent intensive observations of JSR revealed short term variations of JSR with the time scale of days to weeks. Brice and McDonough (1973) proposed a scenario for the short term variations; i.e, the solar UV/EUV heating for Jupiter's upper atmosphere causes enhancement of total flux density. The purpose of this study is to investigate whether sufficient solar UV/EUV heating in Jupiter's upper atmosphere can actually causes variation in the JSR total flux and brightness distribution. Previous JSR observations using the Giant Metrewave Radio Telescope (GMRT) suggested important characteristics of short term variations; relatively low energy particles are accelerated by some acceleration processes which might be driven by solar UV/EUV heating and/or Jupiter's own magnetic activities. In order to evaluate the effect of solar UV/EUV heating on JSR variations, we made coordinated observations using the GMRT and NASA Infra-Red Telescope Facility (IRTF). By using IRTF, we can estimate the temperature of Jupiter's upper atmosphere from spectroscopic observation of H_3^+ infrared emission. Hence, we can evaluate the relationship between variations in Jupiter's upper atmosphere initiated by the solar UV/EUV heating and its linkage with the JSR. The GMRT observations were made during Nov. 6-17, 2011 at the frequency of 235/610MHz. The H_3^+ 3.953 micron line was observed using the IRTF during Nov. 7-12, 2011. During the observation period, the solar UV/EUV flux variations expected on Jupiter showed monotonic increase. A preliminary analysis of GMRT 610MHz band showed a radio flux variation similar to that in the solar UV/EUV. Radio images showed that the emission intensity increased at the outer region and the position of equatorial peak emission moved in the outward direction. If radial diffusion

  12. Surface topography by caustics.

    PubMed

    Theocaris, P S; Gdoutos, E E

    1976-06-01

    The optical method of caustics, initially developed for recording abrupt plate slopes created by singularities in elastic stress fields, was extended to incorporate the study of the general case of any type of surface. A universal technique, based on the general theory of caustics developed in this paper, was formulated to study the topography of any surface from its corresponding caustics obtained by illuminating the surface by a parallel, convergent, or divergent light beam. The special case of an axisymmetric mirror with elliptical cross section, whose ellipticity varies from zero to infinity, was studied extensively to show the potentialities of the technique developed. It was shown that the caustics obtained are very sensitive to the particular form of the surface considered. From the procedure developed in this paper it was concluded that the method of caustics can be successfully used to record the topography of any surface with large or infinitesimal slopes.

  13. 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.

  14. 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.

  15. 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

  16. 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

  17. 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

  18. Isostasy, flexure, and dynamic topography

    NASA Astrophysics Data System (ADS)

    Gvirtzman, Zohar; Faccenna, Claudio; Becker, Thorsten W.

    2016-06-01

    A fundamental scientific question is, what controls the Earth's topography? Although the theoretical principles of isostasy, flexure, and dynamic topography are widely discussed, the parameters needed to apply these principles are frequently not available. Isostatic factors controlling lithospheric buoyancy are frequently uncertain and non-isostatic factors, such as lithospheric bending towards subduction zones and dynamic topography, are hard to distinguish. The question discussed here is whether a set of simple rules that relate topography to lithospheric structure in various tectonic environments can be deduced in a way that missing parameters can be approximated; or does each area behave differently, making generalizations problematic. We contribute to this issue analyzing the Asia-Africa-Arabia-Europe domain following a top-down strategy. We compile a new crustal thickness map and remove the contribution of the crust from the observed elevation. Then, the challenge is to interpret the residual topography in terms of mantle lithosphere buoyancy and dynamics. Based on systematic relationships between tectonic environments and factors controlling topography, we argue that crustal buoyancy and mantle lithospheric density can be approximated from available geological data and that regions near mantle upwelling or downwelling are easily identified by their extreme residual topography. Yet, even for other areas, calculating lithospheric thickness from residual topography is problematic, because distinguishing variations in mantle lithosphere thickness from sub-lithospheric dynamics is difficult. Fortunately, the area studied here provides an opportunity to examine this issue. Based on the conjunction between the Afar Plume and the mid-ocean ridge in the nearby Gulf of Aden and southern Red Sea, we constrain the maximal amplitude of dynamic topography to ~ 1 km. This estimate is based on a narrow definition of dynamic topography that only includes sub

  19. Mantle convection, topography and geoid

    NASA Astrophysics Data System (ADS)

    Golle, Olivia; Dumoulin, Caroline; Choblet, Gaël.; Cadek, Ondrej

    2010-05-01

    The internal evolution of planetary bodies often include solid-state convection. This phenomenon may have a large impact on the various interfaces of these bodies (dynamic topography occurs). It also affects their gravity field (and the geoid). Since both geoid and topography can be measured by a spacecraft, and are therefore available for several planetary bodies (while seismological measurements are still lacking for all of them but the Moon and the Earth), these are of the first interest for the study of internal structures and processes. While a classical approach now is to combine gravity and altimetry measurements to infer the internal structure of a planet [1], we propose to complement it by the reverse problem, i.e., producing synthetic geoid and dynamic topography from numerical models of convection as proposed by recent studies (e.g. for the CMB topography of the Earth,[2]). This procedure first include a simple evaluation of the surface topography and geoid from the viscous flow obtained by the 3D numerical tool OEDIPUS [3] modeling convection in a spherical shell. An elastic layer will then be considered and coupled to the viscous model - one question being whether the elastic shell shall be included 'on top' of the convective domain or within it, in the cold 'lithospheric' outer region. What we will present here corresponds to the first steps of this work: the comparison between the response functions of the topography and the geoid obtained from the 3D convection program to the results evaluated by a spectral method handling radial variations of viscosity [4]. We consider the effect of the elastic layer whether included in the convective domain or not. The scale setting in the context of a full thermal convection model overlaid by an elastic shell will be discussed (thickness of the shell, temperature at its base...). References [1] A.M. Wieczorek, (2007), The gravity and topography of the terrestrial planets, Treatise on Geophysics, 10, 165-206. [2

  20. Statistics of topography : multifractal approach to describe planetary topography

    NASA Astrophysics Data System (ADS)

    Landais, Francois; Schmidt, Frédéric; Lovejoy, Shaun

    2016-04-01

    In the last decades, a huge amount of topographic data has been obtained by several techniques (laser and radar altimetry, DTM…) for different bodies in the solar system. In each case, topographic fields exhibit an extremely high variability with details at each scale, from millimeters to thousands of kilometers. In our study, we investigate the statistical properties of the topography. Our statistical approach is motivated by the well known scaling behavior of topography that has been widely studied in the past. Indeed, scaling laws are strongly present in geophysical field and can be studied using fractal formalism. More precisely, we expect multifractal behavior in global topographic fields. This behavior reflects the high variability and intermittency observed in topographic fields that can not be generated by simple scaling models. In the multifractal formalism, each statistical moment exhibits a different scaling law characterized by a function called the moment scaling function. Previous studies were conducted at regional scale to demonstrate that topography present multifractal statistics (Gagnon et al., 2006, NPG). We have obtained similar results on Mars (Landais et al. 2015) and more recently on different body in the the solar system including the Moon, Venus and Mercury. We present the result of different multifractal approaches performed on global and regional basis and compare the fractal parameters from a body to another.

  1. 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.

  2. 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

  3. The Topography Tub Learning Activity

    NASA Astrophysics Data System (ADS)

    Glesener, G. B.

    2014-12-01

    Understanding the basic elements of a topographic map (i.e. contour lines and intervals) is just a small part of learning how to use this abstract representational system as a resource in geologic mapping. Interpretation of a topographic map and matching its features with real-world structures requires that the system is utilized for visualizing the shapes of these structures and their spatial orientation. To enrich students' skills in visualizing topography from topographic maps a spatial training activity has been developed that uses 3D objects of various shapes and sizes, a sighting tool, a plastic basin, water, and transparencies. In the first part of the activity, the student is asked to draw a topographic map of one of the 3D objects. Next, the student places the object into a plastic tub in which water is added to specified intervals of height. The shoreline at each interval is used to reference the location of the contour line the student draws on a plastic inkjet transparency directly above the object. A key part of this activity is the use of a sighting tool by the student to assist in keeping the pencil mark directly above the shoreline. It (1) ensures the accurate positioning of the contour line and (2) gives the learner experience with using a sight before going out into the field. Finally, after the student finishes drawing the contour lines onto the transparency, the student can compare and contrast the two maps in order to discover where improvements in their visualization of the contours can be made. The teacher and/or peers can also make suggestions on ways to improve. A number of objects with various shapes and sizes are used in this exercise to produce contour lines representing the different types of topography the student may encounter while field mapping. The intended outcome from using this visualization training activity is improvement in performance of visualizing topography as the student moves between the topographic representation and

  4. Spectral Topography Generation for Arbitrary Grids

    NASA Astrophysics Data System (ADS)

    Oh, T. J.

    2015-12-01

    A new topography generation tool utilizing spectral transformation technique for both structured and unstructured grids is presented. For the source global digital elevation data, the NASA Shuttle Radar Topography Mission (SRTM) 15 arc-second dataset (gap-filling by Jonathan de Ferranti) is used and for land/water mask source, the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) 30 arc-second land water mask dataset v5 is used. The original source data is coarsened to a intermediate global 2 minute lat-lon mesh. Then, spectral transformation to the wave space and inverse transformation with wavenumber truncation is performed for isotropic topography smoothness control. Target grid topography mapping is done by bivariate cubic spline interpolation from the truncated 2 minute lat-lon topography. Gibbs phenomenon in the water region can be removed by overwriting ocean masked target coordinate grids with interpolated values from the intermediate 2 minute grid. Finally, a weak smoothing operator is applied on the target grid to minimize the land/water surface height discontinuity that might have been introduced by the Gibbs oscillation removal procedure. Overall, the new topography generation approach provides spectrally-derived, smooth topography with isotropic resolution and minimum damping, enabling realistic topography forcing in the numerical model. Topography is generated for the cubed-sphere grid and tested on the KIAPS Integrated Model (KIM).

  5. Bedrock topography of northwest Iowa

    USGS Publications Warehouse

    Hansen, R.E.; Runkle, D.L.

    1986-01-01

    Bedrock in Iowa (Hershey, 1969) generally is overlain by deposits of glacial drive and alluvium. The drift, consisting of glacial till and glacial outwash, ranges in thickness from zero to more than 500 feet in western Iowa; the alluvium in stream valleys ranges in thickness from less than 1 foot to more than 70 feet. The configuration of the bedrock surface is the result of a complex system of ancient drainage courses that were developed during a long period of preglacial erosion. This map, for a 12 county area in west-central Iowa, is the eighth in a series of nine reports that will provide statewide coverage of the bedriock topography of Iowa. 

  6. 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.

  7. Enhanced characterization of niobium surface topography

    NASA Astrophysics Data System (ADS)

    Xu, Chen; Tian, Hui; Reece, Charles E.; Kelley, Michael J.

    2011-12-01

    Surface topography characterization is a continuing issue for the superconducting radio frequency (SRF) particle accelerator community. Efforts are under way to both 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 the process modifies topography at different scales. However, generating an accurate and meaningful topographic PSD of an SRF surface requires careful analysis and optimization. In this report, niobium surfaces with different process histories are sampled with atomic force microscopy and stylus profilometry and analyzed to trace topography evolution at different scales. An optimized PSD analysis protocol to serve SRF needs is presented.

  8. 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

  9. 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

  10. Shuttle Radar Topography Mission (SRTM)

    USGS Publications Warehouse

    ,

    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.

  11. Shuttle Radar Topography Mission (SRTM)

    USGS Publications Warehouse

    ,

    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.

  12. 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.

  13. 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.

  14. Problems in determining sea surface topography

    NASA Technical Reports Server (NTRS)

    Whitehead, J. A., Jr.

    1978-01-01

    Anticipated problems for determining ocean dynamics signals from sea surface topography are discussed. The needs for repeated tracks are listed if oceanic tides or ocean turbulence are to be determined.

  15. Dynamic Topography of Oceans and Continents

    NASA Astrophysics Data System (ADS)

    Lithgow-Bertelloni, C.; Conrad, C. P.

    2004-05-01

    The large contrasts in surface topography are one of the most striking features of our planet. Contributions to topography range from short-wavelength uncompensated features due to tectonic activity, to variations in crustal thickness and density structure and long-wavelength deflections of the lithosphere caused by mantle dynamics. Upwelling or downwelling flow in Earth's mantle can elevate or depress the earth's surface even if the sources of buoyancy are deep in the mantle. However, direct observation of this ``dynamic topography'' has been elusive, because it is obscured by the isostatic contribution due to crustal and lithospheric structure. Any potential confirmation of the role of dynamic topography, sheds light not only on the impact of mantle dynamics on surface processes, but also on the nature of mantle dynamics itself. For example, we expect dramatically different topographic signals from layered vs. whole mantle convection. We have learned a great deal about the consequences of dynamic topography for continental flooding and the formation of large sedimentary basins since the pioneering work of Mitrovica et al. [1989] and Gurnis [1990]. Recently, unequivocal signals of dynamically supported topography have been found in both continents (Africa [Lithgow-Bertelloni and Silver, 1998] and Arabia [Daradich et al., 2004]) and oceanic basins (North-Atlantic [Conrad et al., 2004]). In all three cases, the identifiable dynamic topography signal results from upwelling mantle. In regions associated with downwellings considerable controversy remains [e.g. Wheeler and White, 2002]. There is a hint in this result that relates to the ability of slabs to penetrate into the lower mantle and of upwellings to reach the surface from great depth. We review in this talk the evidence for dynamic topography in continents and oceans, and present some speculations related to the nature of layering in mantle convection.

  16. 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.

  17. Electronic Cigarette Topography in the Natural Environment.

    PubMed

    Robinson, R J; Hensel, E C; 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.

  18. Experiments on topographies lacking tidal conversion

    NASA Astrophysics Data System (ADS)

    Maas, Leo; Paci, Alexandre; Yuan, Bing

    2015-11-01

    In a stratified sea, internal tides are supposedly generated when the tide passes over irregular topography. It has been shown that for any given frequency in the internal wave band there are an infinite number of exceptions to this rule of thumb. This ``stealth-like'' property of the topography is due to a subtle annihilation of the internal waves generated during the surface tide's passage over the irregular bottom. We here demonstrate this in a lab-experiment. However, for any such topography, subsequently changing the surface tide's frequency does lead to tidal conversion. The upshot of this is that a tidal wave passing over an irregular bottom is for a substantial part trapped to this irregularity, and only partly converted into freely propagating internal tides. Financially supported by the European Community's 7th Framework Programme HYDRALAB IV.

  19. Moiré topography in odontology

    NASA Astrophysics Data System (ADS)

    Moreno Yeras, A.

    2003-07-01

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

  20. 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

  1. Noninterferometric topography measurements of fast moving surfaces.

    PubMed

    Pinhasi, Shirly Vinikman; Eliezer, Shalom; Glam, Benny; Appelbaum, Gabi; Bakshi, Lior

    2011-08-01

    The topography of moving surfaces is recovered by noninterferometric measurements. The phase reconstruction is derived by measuring the intensities of a backscattered pulsed laser light and solving the transport intensity equation (TIE). The TIE is solved by expanding the phase into a series of Zernike polynomials, leading to a set of appropriate algebraic equations. This technique, which enables us to make a direct connection between experiments and the TIE, has been successfully tested in gas gun experiments. In particular, the topographies of a moving projectile and the free surface of a shocked target were recovered. PMID:21811317

  2. Simple method for decreasing wafer topography effect for implant mask

    NASA Astrophysics Data System (ADS)

    You, Taejun; Lee, Taehyeong; Yoo, Gyun; Park, Youngjoon; Kim, Cheolkyun; Yim, Donggyu

    2016-03-01

    Controlling critical dimension (CD) of implant blocking layers during photolithography has been challenging due to reflection caused by wafer topography. Unexpected reflection which comes from wafer topography makes severe CD variation on mask patterns of implant layer. Using bottom antireflective coatings(BARCs) can reduce the topography effect, but it could also damage wafer surface during BARCs dry etching. Developable BARCs(D-BARCs) could be alternative solution for wafer topography effect. However there are some issues that should be considered in D-BARCs process such as sensitive temperature control and managing defects. There are also papers introducing model based topography aware OPC as a solution for wafer topography effect implant layer. But building topography aware OPC model is very complex and it takes too much time to build. In this paper, we will introduce experimental results of wafer topography effect using various test patterns and propose a simple method that could effectively reduce wafer topography effect.

  3. Spike voltage topography in temporal lobe epilepsy.

    PubMed

    Asadi-Pooya, Ali A; Asadollahi, Marjan; Shimamoto, Shoichi; Lorenzo, Matthew; Sperling, Michael R

    2016-07-15

    We investigated the voltage topography of interictal spikes in patients with temporal lobe epilepsy (TLE) to see whether topography was related to etiology for TLE. Adults with TLE, who had epilepsy surgery for drug-resistant seizures from 2011 until 2014 at Jefferson Comprehensive Epilepsy Center were selected. Two groups of patients were studied: patients with mesial temporal sclerosis (MTS) on MRI and those with other MRI findings. The voltage topography maps of the interictal spikes at the peak were created using BESA software. We classified the interictal spikes as polar, basal, lateral, or others. Thirty-four patients were studied, from which the characteristics of 340 spikes were investigated. The most common type of spike orientation was others (186 spikes; 54.7%), followed by lateral (146; 42.9%), polar (5; 1.5%), and basal (3; 0.9%). Characteristics of the voltage topography maps of the spikes between the two groups of patients were somewhat different. Five spikes in patients with MTS had polar orientation, but none of the spikes in patients with other MRI findings had polar orientation (odds ratio=6.98, 95% confidence interval=0.38 to 127.38; p=0.07). Scalp topographic mapping of interictal spikes has the potential to offer different information than visual inspection alone. The present results do not allow an immediate clinical application of our findings; however, detecting a polar spike in a patient with TLE may increase the possibility of mesial temporal sclerosis as the underlying etiology. PMID:27288809

  4. Detecting and Quantifying Topography in Neural Maps

    PubMed Central

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

    2014-01-01

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

  5. Spike voltage topography in temporal lobe epilepsy.

    PubMed

    Asadi-Pooya, Ali A; Asadollahi, Marjan; Shimamoto, Shoichi; Lorenzo, Matthew; Sperling, Michael R

    2016-07-15

    We investigated the voltage topography of interictal spikes in patients with temporal lobe epilepsy (TLE) to see whether topography was related to etiology for TLE. Adults with TLE, who had epilepsy surgery for drug-resistant seizures from 2011 until 2014 at Jefferson Comprehensive Epilepsy Center were selected. Two groups of patients were studied: patients with mesial temporal sclerosis (MTS) on MRI and those with other MRI findings. The voltage topography maps of the interictal spikes at the peak were created using BESA software. We classified the interictal spikes as polar, basal, lateral, or others. Thirty-four patients were studied, from which the characteristics of 340 spikes were investigated. The most common type of spike orientation was others (186 spikes; 54.7%), followed by lateral (146; 42.9%), polar (5; 1.5%), and basal (3; 0.9%). Characteristics of the voltage topography maps of the spikes between the two groups of patients were somewhat different. Five spikes in patients with MTS had polar orientation, but none of the spikes in patients with other MRI findings had polar orientation (odds ratio=6.98, 95% confidence interval=0.38 to 127.38; p=0.07). Scalp topographic mapping of interictal spikes has the potential to offer different information than visual inspection alone. The present results do not allow an immediate clinical application of our findings; however, detecting a polar spike in a patient with TLE may increase the possibility of mesial temporal sclerosis as the underlying etiology.

  6. Decoupling of modern shortening rates, climate, and topography in the Caucasus

    NASA Astrophysics Data System (ADS)

    Forte, Adam M.; Whipple, Kelin X.; Bookhagen, Bodo; Rossi, Matthew W.

    2016-09-01

    The Greater and Lesser Caucasus mountains and their associated foreland basins contain similar rock types, experience a similar two-fold, along-strike variation in mean annual precipitation, and were affected by extreme base-level drops of the neighboring Caspian Sea. However, the two Caucasus ranges are characterized by decidedly different tectonic regimes and rates of deformation that are subject to moderate (less than an order of magnitude) gradients in climate, and thus allow for a unique opportunity to isolate the effects of climate and tectonics in the evolution of topography within active orogens. There is an apparent disconnect between modern climate, shortening rates, and topography of both the Greater Caucasus and Lesser Caucasus which exhibit remarkably similar topography along-strike despite the gradients in forcing. By combining multiple datasets, we examine plausible causes for this disconnect by presenting a detailed analysis of the topography of both ranges utilizing established relationships between catchment-mean erosion rates and topography (local relief, hillslope gradients, and channel steepness) and combining it with a synthesis of previously published low-temperature thermochronologic data. Modern climate of the Caucasus region is assessed through an analysis of remotely-sensed data (TRMM and MODIS) and historical streamflow data. Because along-strike variation in either erosional efficiency or thickness of accreted material fail to explain our observations, we suggest that the topography of both the western Lesser and Greater Caucasus are partially supported by different geodynamic forces. In the western Lesser Caucasus, high relief portions of the landscape likely reflect uplift related to ongoing mantle lithosphere delamination beneath the neighboring East Anatolian Plateau. In the Greater Caucasus, maintenance of high topography in the western portion of the range despite extremely low (<2-4 mm/y) modern convergence rates may be related

  7. 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.

  8. Impact of watershed topography on hyporheic exchange

    NASA Astrophysics Data System (ADS)

    Caruso, Alice; Ridolfi, Luca; Boano, Fulvio

    2016-08-01

    Among the interactions between surface water bodies and aquifers, hyporheic exchange has been recognized as a key process for nutrient cycling and contaminant transport. Even though hyporheic exchange is strongly controlled by groundwater discharge, our understanding of the impact of the regional groundwater flow on hyporheic fluxes is still limited because of the complexity arising from the multi-scale nature of these interactions. In this work, we investigate the role of watershed topography on river-aquifer interactions by way of a semi-analytical model, in which the landscape topography is used to approximate the groundwater head distribution. The analysis of a case study shows how the complex topographic structure is the direct cause of a substantial spatial variability of the aquifer-river exchange. Groundwater upwelling along the river corridor is estimated and its influence on the hyporheic zone is discussed. In particular, the fragmentation of the hyporeic corridor induced by groundwater discharge at the basin scale is highlighted.

  9. Description of two-process surface topography

    NASA Astrophysics Data System (ADS)

    Grabon, W.; Pawlus, P.

    2014-04-01

    After two machining processes, a large number of surface topography measurements were made using Talyscan 150 stylus measuring equipment. The measured samples were divided into two groups. The first group contained two-process surfaces of random nature, while the second group used random-deterministic textures of random plateau parts and portions of deterministic valleys. For comparison, one-process surfaces were also analysed. Correlation and regression analysis was used to study the dependencies among surface texture parameters in 2D and 3D systems. As the result of this study, sets of parameters describing multi-process surface topography were obtained for two-process surfaces of random and of random-deterministic types.

  10. Interferometric measurements of fine corneal topography

    NASA Astrophysics Data System (ADS)

    Kasprzak, Henryk T.; Kowalik, Waldemar; Jaronski, Jaroslaw W.

    1995-02-01

    The cornea is the most refractive element in the eye. Its refractive power is about 70% of the power of the whole eye. The shape of the cornea is aspheric, and almost always has no rotational symmetry. Even small surface irregularities can cause a perceptible reduction in visual acuity. Standard methods for evaluation of the corneal topography used in clinical practice include keratometry, photokeratoscopy, and computer assisted videokeratography. All of these methods used the principles of geometrical optics, and their accuracy is about 0.25 D. An application of interference phenomenon's to examine the corneal contour map significantly increase the accuracy. Using the interferometric inspection of the corneal shape one can easily observe the fine corneal topography, the fast, dynamic changes of the corneal surface, and the topology of the tear film and its irregularities. The paper presents the Twyman Green interferometer, used in experiments, an example of sequence of interferograms and their 3D presentations.

  11. Topography on satellite surfaces and the shape of asteroids.

    NASA Technical Reports Server (NTRS)

    Johnson, T. V.; Mcgetchin, T. R.

    1973-01-01

    Consideration of the topography and shape of incompressible, nonrotating, isothermal, spherical objects as an approach to the study of the topography and shape of smaller planetary bodies. A static model and a creep deformation model are applied in the process. Factors and forces which may have a bearing on the geometry and topography of small planetary bodies are discussed.

  12. Diffraction imaging (topography) with monochromatic synchrotron radiation

    SciTech Connect

    Steiner, B.; Kuriyama, M.; Dobbyn, R.C.; Laor, U.

    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.

  13. 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.

  14. 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

  15. 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

  16. Practical aspects of a corneal topography system.

    PubMed

    McCarey, B E; Zurawski, C A; O'Shea, D S

    1992-10-01

    We used the EyeSys Corneal Topography System to examine several issues relating to corneal topography systems and the interpretation of their results. Interferometry measurements of EyeSys calibration spheres indicated that they deviated from suggested values by 0.05 +/- 0.13 D (mean +/- 1 standard deviation). The EyeSys unit reliably determined the calibration spheres to be spherical with differences between the flat and steep axis of 0.10 +/- 0.09 D. The data for the 3 mm chord circle was the least reliable. The spherical equivalent values for the calibration spheres were constantly greater than the 0.25 D reproducibility suggested by the manufacturer. Furthermore, the precision of the outputted values (0.01 D) is beyond the capability of the instrument. This gives the impression that the topography unit cannot consistently reproduce measurements of the calibration objects or chrome plated steel spheres. Image centralization and focus were found to be critical in obtaining accurate results. A target off center by more than 0.25 mm resulted in unreliable data; increasing the focal distance by greater than 1 mm beyond the focal point resulted in a sharp decrease in accuracy (a decrease in the focal distance was even more critical). When measuring aspheric contact lenses, it was found that the keratometer and EyeSys unit provided a close approximation of the surface characteristics of the lenses. A realistic view of the limitations of the topography system being used is critical for proper interpretation of the data.

  17. 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.

  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.

  19. 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.

  20. Solutions of barotropic trapped waves over topography

    NASA Astrophysics Data System (ADS)

    Zavala Sanson, Luis

    2010-05-01

    Solutions of free, barotropic waves over variable topography are derived. In particular, we examine two cases: waves around axisymmetric seamounts and waves along a sloping bottom. Even though these types of oscillations have been studied before, we revisit the problem because of two main reasons: (i) The linear, barotropic, shallow-water equations with a rigid lid are now solved with no further approximations, in contrast with previous studies. (ii) The solutions are applied to a wide family of seamounts and bottom slopes with profiles proportional to exp(rs) and ys, respectively, where r is the radial distance from the centre of the mountain, y is the direction perpendicular to the slope, and s is an arbitrary positive real number. Most of previous works on seamounts are restricted to the special case s = 2. By varying the shape parameter one can study trapped waves around flat-topped seamounts or guyots (s > 2) or sharp, cone-shaped topographies (s < 2). Similarly, most of previous studies on sloping bottoms report cases with s = 1 (linear slopes), whilst the present results are applied to more general bottom profiles. The resulting dispersion relation in both cases possess a remarkable simplicity that reveals a number of wave characteristics as a function of the topography shape.

  1. 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.

  2. EAARL topography: Cape Cod National Seashore

    USGS Publications Warehouse

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

    2007-01-01

    This Web site contains 90 Lidar-derived bare earth topography maps and GIS files for the Cape Cod National Seashore. 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), 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.

  3. EAARL topography: Assateague Island National Seashore

    USGS Publications Warehouse

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

    2007-01-01

    This Web site contains 58 lidar-derived bare earth topography maps and GIS files for the Assateague Island National Seashore. 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, 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.

  4. EAARL topography: Thomas Stone National Historic Site

    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 Thomas Stone National Historic Site in Maryland. 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.

  5. EAARL topography: Gulf Islands National Seashore: Florida

    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 33 lidar-derived bare earth topography maps and GIS files for the Gulf Islands National Seashore-Florida. 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, Florida, the National Park Service (NPS), Gulf Coast Network, 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.

  6. 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.

  7. 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.

  8. EAARL topography: Gulf Islands National Seashore: Mississippi

    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 30 lidar-derived bare earth topography maps and GIS files for the Gulf Islands National Seashore-Mississippi. 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, 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.

  9. Interferometer for measuring dynamic corneal topography

    NASA Astrophysics Data System (ADS)

    Micali, Jason Daniel

    The cornea is the anterior most surface of the eye and plays a critical role in vision. A thin fluid layer, the tear film, coats the outer surface of the cornea and serves to protect, nourish, and lubricate the cornea. At the same time, the tear film is responsible for creating a smooth continuous surface where the majority of refraction takes place in the eye. A significant component of vision quality is determined by the shape of the cornea and stability of the tear film. It is desirable to possess an instrument that can measure the corneal shape and tear film surface with the same accuracy and resolution that is currently performed on common optical elements. A dual interferometer system for measuring the dynamic corneal topography is designed, built, and verified. The completed system is validated by testing on human subjects. The system consists of two co-aligned polarization splitting Twyman-Green interferometers designed to measure phase instantaneously. The primary interferometer measures the surface of the tear film while the secondary interferometer simultaneously tracks the absolute position of the cornea. Eye motion, ocular variation, and a dynamic tear film surface will result in a non-null configuration of the surface with respect to the interferometer system. A non-null test results in significant interferometer induced errors that add to the measured phase. New algorithms are developed to recover the absolute surface topography of the tear film and corneal surface from the simultaneous interferometer measurements. The results are high-resolution and high-accuracy surface topography measurements of the in vivo cornea that are captured at standard camera frame rates. This dissertation will cover the development and construction of an interferometer system for measuring the dynamic corneal topography of the human eye. The discussion starts with the completion of an interferometer for measuring the tear film. The tear film interferometer is part of an

  10. 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

  11. 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-κB 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 α, 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 α 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

  12. 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.

  13. 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

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. Evaluation of facial palsy by moire topography

    NASA Astrophysics Data System (ADS)

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

    1991-08-01

    Society of Facial Research is used frequently. It is of great value clinically, but the method has several weak points concerning objective and quantitative assessment. This study uses moire topography to solve these problems. mA moire camera, FM3013, of the lattice irradiation type was used for measurement of the face. Five moire photographs were taken: at rest, wrinkling the forehead, closing the eyes lightly, blowing out the cheeks and grinning. The degree of facial palsy was determined by the Asymmetry Index (AI) as a measure of the degree of facial deviation. Total AI was expressed as the average AI based on calculations of the measurement in 5 photos. Severe paralysis is represented by an AI of more than 20%. Partial paralysis has a range of 20-8%. Nearly normal is judged to be less than 8%. Ten normal individuals are measured as control and show an AI of 3% or less. Moire topography is useful in assessing the recovery process because it has the benefit of making the site and grade of palsy easily achieved by the AI and the deviation in its patterns. The authors propose that the moire method is better for an objective and quantitative evaluation than the society's method.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. 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

  6. Forecasting Hurricane Impact on Coastal Topography

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

    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.

  7. EAARL submarine topography: Biscayne National Park

    USGS Publications Warehouse

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

    2006-01-01

    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, and event assessment (for example: bleaching, hurricanes, disease outbreaks). As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring water depth and conducting cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to managers of coastal tropical habitats.

  8. 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.

  9. 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.

  10. 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.

  11. Topographies of forensic practice in Imperial Germany.

    PubMed

    Engstrom, Eric J

    2014-01-01

    This article examines the topography and "cultural machinery" of forensic jurisdictions in Imperial Germany. It locates the sites at which boundary disputes between psychiatric and legal professionals arose and explores the strategies and practices that governed the division of expert labor between them. It argues that the over-determined paradigms of 'medicalization' and 'biologization' have lost much of their explanatory force and that historians need to refocus their attention on the institutional and administrative configuration of forensic practices in Germany. After first sketching the statutory context of those practices, the article explores how contentious jurisdictional negotiations pitted various administrative, financial, public security, and scientific interests against one another. The article also assesses the contested status of psychiatric expertise in the courtroom, as well as post-graduate forensic psychiatric training courses and joint professional organizations, which drew the two professional communities closer together and mediated their jurisdictional disputes.

  12. EAARL topography: Fire Island National Seashore

    USGS Publications Warehouse

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

    2007-01-01

    This Web site contains 31 LIDAR-derived first return topography maps and GIS files for Fire Island National Seashore. These lidar-derived topographic maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, 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. The aims of the partnership that created this product are to develop advanced survey techniques for mapping barrier island geomorphology and habitats, and to enable the monitoring of ecological and geological change within National Seashores. This product is based on data from an innovative airborne lidar instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Advanced Airborne Research Lidar (EAARL).

  13. Electroencephalographic topography measures of experienced utility.

    PubMed

    Pedroni, Andreas; Langer, Nicolas; Koenig, Thomas; Allemand, Michael; Jäncke, Lutz

    2011-07-20

    Economic theory distinguishes two concepts of utility: decision utility, objectively quantifiable by choices, and experienced utility, referring to the satisfaction by an obtainment. To date, experienced utility is typically measured with subjective ratings. This study intended to quantify experienced utility by global levels of neuronal activity. Neuronal activity was measured by means of electroencephalographic (EEG) responses to gain and omission of graded monetary rewards at the level of the EEG topography in human subjects. A novel analysis approach allowed approximating psychophysiological value functions for the experienced utility of monetary rewards. In addition, we identified the time windows of the event-related potentials (ERP) and the respective intracortical sources, in which variations in neuronal activity were significantly related to the value or valence of outcomes. Results indicate that value functions of experienced utility and regret disproportionally increase with monetary value, and thus contradict the compressing value functions of decision utility. The temporal pattern of outcome evaluation suggests an initial (∼250 ms) coarse evaluation regarding the valence, concurrent with a finer-grained evaluation of the value of gained rewards, whereas the evaluation of the value of omitted rewards emerges later. We hypothesize that this temporal double dissociation is explained by reward prediction errors. Finally, a late, yet unreported, reward-sensitive ERP topography (∼500 ms) was identified. The sources of these topographical covariations are estimated in the ventromedial prefrontal cortex, the medial frontal gyrus, the anterior and posterior cingulate cortex and the hippocampus/amygdala. The results provide important new evidence regarding "how," "when," and "where" the brain evaluates outcomes with different hedonic impact.

  14. 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.

  15. 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.

  16. Corneal topography matching by iterative registration.

    PubMed

    Wang, Junjie; Elsheikh, Ahmed; Davey, Pinakin G; Wang, Weizhuo; Bao, Fangjun; Mottershead, John E

    2014-11-01

    Videokeratography is used for the measurement of corneal topography in overlapping portions (or maps) which must later be joined together to form the overall topography of the cornea. The separate portions are measured from different viewpoints and therefore must be brought together by registration of measurement points in the regions of overlap. The central map is generally the most accurate, but all maps are measured with uncertainty that increases towards the periphery. It becomes the reference (or static) map, and the peripheral (or dynamic) maps must then be transformed by rotation and translation so that the overlapping portions are matched. The process known as registration, of determining the necessary transformation, is a well-understood procedure in image analysis and has been applied in several areas of science and engineering. In this article, direct search optimisation using the Nelder-Mead algorithm and several variants of the iterative closest/corresponding point routine are explained and applied to simulated and real clinical data. The measurement points on the static and dynamic maps are generally different so that it becomes necessary to interpolate, which is done using a truncated series of Zernike polynomials. The point-to-plane iterative closest/corresponding point variant has the advantage of releasing certain optimisation constraints that lead to persistent registration and alignment errors when other approaches are used. The point-to-plane iterative closest/corresponding point routine is found to be robust to measurement noise, insensitive to starting values of the transformation parameters and produces high-quality results when using real clinical data.

  17. Electroencephalographic topography measures of experienced utility.

    PubMed

    Pedroni, Andreas; Langer, Nicolas; Koenig, Thomas; Allemand, Michael; Jäncke, Lutz

    2011-07-20

    Economic theory distinguishes two concepts of utility: decision utility, objectively quantifiable by choices, and experienced utility, referring to the satisfaction by an obtainment. To date, experienced utility is typically measured with subjective ratings. This study intended to quantify experienced utility by global levels of neuronal activity. Neuronal activity was measured by means of electroencephalographic (EEG) responses to gain and omission of graded monetary rewards at the level of the EEG topography in human subjects. A novel analysis approach allowed approximating psychophysiological value functions for the experienced utility of monetary rewards. In addition, we identified the time windows of the event-related potentials (ERP) and the respective intracortical sources, in which variations in neuronal activity were significantly related to the value or valence of outcomes. Results indicate that value functions of experienced utility and regret disproportionally increase with monetary value, and thus contradict the compressing value functions of decision utility. The temporal pattern of outcome evaluation suggests an initial (∼250 ms) coarse evaluation regarding the valence, concurrent with a finer-grained evaluation of the value of gained rewards, whereas the evaluation of the value of omitted rewards emerges later. We hypothesize that this temporal double dissociation is explained by reward prediction errors. Finally, a late, yet unreported, reward-sensitive ERP topography (∼500 ms) was identified. The sources of these topographical covariations are estimated in the ventromedial prefrontal cortex, the medial frontal gyrus, the anterior and posterior cingulate cortex and the hippocampus/amygdala. The results provide important new evidence regarding "how," "when," and "where" the brain evaluates outcomes with different hedonic impact. PMID:21775593

  18. 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.

  19. 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.

  20. Graphene Topographies: Multiscale Graphene Topographies Programmed by Sequential Mechanical Deformation (Adv. Mater. 18/2016).

    PubMed

    Chen, Po-Yen; Sodhi, Jaskiranjeet; Qiu, Yang; Valentin, Thomas M; Steinberg, Ruben Spitz; Wang, Zhongying; Hurt, Robert H; Wong, Ian Y

    2016-05-01

    P.-Y. Chen, R. H. Hurt, I. Y. Wong and co-workers demonstrate a hierarchical graphene surface architecture generated by using various sequences and combinations of extreme mechanical deformation, as shown in the false-colored SEM image. As described on page 3564, the sequential patterning approach enables the design of feature sizes and orientations across multiple length scales which are retained during mechanical deformations of similar extent. This results in sequence-dependent surface topographies with structural memory. PMID:27151628

  1. 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.

  2. X-ray topography utilizing non-equatorial reflections

    NASA Astrophysics Data System (ADS)

    Kingman, P. W.

    1987-03-01

    A technique for back reflection topography has been developed which uses nonequatorial reflections. The geometry of back reflection topography is analyzed in a general way, and it is shown how this analysis can be used for systematic imaging and contrast strategies. A novel camera design based upon this approach is also presented.

  3. 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...

  4. Synthetic river valleys: Creating prescribed topography for form-process inquiry and river rehabilitation design

    NASA Astrophysics Data System (ADS)

    Brown, R. A.; Pasternack, G. B.; Wallender, W. W.

    2014-06-01

    The synthesis of artificial landforms is complementary to geomorphic analysis because it affords a reflection on both the characteristics and intrinsic formative processes of real world conditions. Moreover, the applied terminus of geomorphic theory is commonly manifested in the engineering and rehabilitation of riverine landforms where the goal is to create specific processes associated with specific morphology. To date, the synthesis of river topography has been explored outside of geomorphology through artistic renderings, computer science applications, and river rehabilitation design; while within geomorphology it has been explored using morphodynamic modeling, such as one-dimensional simulation of river reach profiles, two-dimensional simulation of river networks, and three-dimensional simulation of subreach scale river morphology. To date, no approach allows geomorphologists, engineers, or river rehabilitation practitioners to create landforms of prescribed conditions. In this paper a method for creating topography of synthetic river valleys is introduced that utilizes a theoretical framework that draws from fluvial geomorphology, computer science, and geometric modeling. Such a method would be valuable to geomorphologists in understanding form-process linkages as well as to engineers and river rehabilitation practitioners in developing design surfaces that can be rapidly iterated. The method introduced herein relies on the discretization of river valley topography into geometric elements associated with overlapping and orthogonal two-dimensional planes such as the planform, profile, and cross section that are represented by mathematical functions, termed geometric element equations. Topographic surfaces can be parameterized independently or dependently using a geomorphic covariance structure between the spatial series of geometric element equations. To illustrate the approach and overall model flexibility examples are provided that are associated with

  5. 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

  6. 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

  7. Mask topography effect in chromeless phase lithography

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

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

  8. 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

  9. Nano-topography sensing by osteoclasts.

    PubMed

    Geblinger, Dafna; Addadi, Lia; Geiger, Benjamin

    2010-05-01

    Bone resorption by osteoclasts depends on the assembly of a specialized, actin-rich adhesive 'sealing zone' that delimits the area designed for degradation. In this study, we show that the level of roughness of the underlying adhesive surface has a profound effect on the formation and stability of the sealing zone and the associated F-actin. As our primary model substrate, we use 'smooth' and 'rough' calcite crystals with average topography values of 12 nm and 530 nm, respectively. We show that the smooth surfaces induce the formation of small and unstable actin rings with a typical lifespan of approximately 8 minutes, whereas the sealing zones formed on the rough calcite surfaces are considerably larger, and remain stable for more than 6 hours. It was further observed that steps or sub-micrometer cracks on the smooth surface stimulate local ring formation, raising the possibility that similar imperfections on bone surfaces may stimulate local osteoclast resorptive activity. The mechanisms whereby the physical properties of the substrate influence osteoclast behavior and their involvement in osteoclast function are discussed.

  10. 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.

  11. 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

  12. 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.

  13. Ocean topography experiment (TOPEX) radar altimeter

    NASA Astrophysics Data System (ADS)

    Rossi, L. C.; Hancock, D. W.; Hayne, G. S.

    A spaceflight qualified Radar Altimeter capable of achieving the TOPEX Mission measurement precision requirement of 2-centimeters, is provided and its performance (Engineering Assessment) will be evaluated after launch and continuously during its 3-year mission operational period. Information will be provided to JPL about the calibration of the TOPEX Radar Altimeter. The specifications for the required data processing algorithms which will be necessary to convert the Radar Altimeter mission telemetry data into the geophysical data will also be provided. The stringent 2 cm precision requirement for ocean topography determination from space necessitated examining existing Radar Altimeter designs for their applicability towards TOPEX. As a result, a system configuration evolved using some flight proven designs in conjunction with needed improvements which include: (1) a second frequency or channel to remove the range delay or apparent height bias caused by the electron content of the ionosphere; (2) higher transmit pulse repetition frequencies for correlation benefits at higher sea states to maintain precision; and (3) a faster microprocessor to accommodate two channels of altimetry data. Additionally, examination of past altimeter programs associated data processing algorithms was accomplished to establish the TOPEX-class Radar Altimeter data processing algorithms, and the necessary direction was outlined to begin to generate these for the TOPEX Mission.

  14. 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.

  15. Topography Simulation for Nanometer Semiconductor Process

    NASA Astrophysics Data System (ADS)

    Lee, Jun‑Gu; Yoon, Sukin; Won, Taeyoung

    2006-04-01

    In this paper, we propose a novel scheme for simulating the topography of nanometer semiconductor processes. Since the proposed scheme considers only the surface cells moving forward and backward during etching or deposition, the simulator does not suffer from an increased memory requirement due to the complexity of the high aspect-ratio structure built on the wafer. This method consists of steps for calculating the front surface moving forward and backward and converting the cell structure into a tetrahedral mesh structure for subsequent numerical simulation. This method mitigates the excessive memory requirement through a dynamic allocating scheme wherein only topographical data at the surface cell are taken into account. A spillover algorithm is also implemented in the simulator so that any excessive etching or deposition which is more than the rate acceptable at the exposed cell during a single time step is reconsidered in the adjacent cells. Our proposed scheme was verified for structures with complex geometry, such as a thin film transistor-liquid crystal display (TFT-LCD) structure, a read only memory (ROM) or a dynamic random access memory (DRAM) cell.

  16. Spreading of droplet with insoluble surfactant on corrugated topography

    NASA Astrophysics Data System (ADS)

    Li, Chunxi; Pei, Jianjun; Ye, Xuemin

    2014-09-01

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

  17. Dynamic and reversible surface topography influences cell morphology.

    PubMed

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

    2013-08-01

    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, ΔRRMS , ranged from 0.05 to 0.70 μm 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 μm, 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.

  18. An Improved 360 Degree and Order Model of Venus Topography

    NASA Technical Reports Server (NTRS)

    Rappaport, Nicole J.; Konopliv, Alex S.; Kucinskas, Algis B.; Ford, Peter G.

    1999-01-01

    We present an improved 360 degree and order spherical harmonic solution for Venus' topography. The new model uses the most recent set of Venus altimetry data with spacecraft positions derived from a recent high resolution gravity model. Geometric analysis indicates that the offset between the center of mass and center of figure of Venus is about 10 times smaller than that for the Earth, the Moon, or Mars. Statistical analyses confirm that the RMS topography follows a power law over the central part of the spectrum. Compared to the previous topography model, the new model is more highly correlated with Venus' harmonic gravity field.

  19. Dewetting of evaporating thin films over nanometer-scale topographies

    NASA Astrophysics Data System (ADS)

    Akbarzadeh, A. M.; Moosavi, A.; Moghimi Kheirabadi, A.

    2014-07-01

    A lubrication model is used to study dewetting of an evaporating thin film layer over a solid substrate with a nanometer-scale topography. The effects of the geometry of the topography, the contact angle, the film thickness, and the slippage on the dewetting have been studied. Our results reveal that the evaporation enhances the dewetting process and reduces the depinning time over the topography. Also it is shown that the depinning time is inversely proportional to the slippage and increasing the contact angle may considerably reduce the depinning time, while the film thickness increases the depinning time.

  20. 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

  1. 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

  2. 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.

  3. 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

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

    PubMed

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

    2015-08-14

    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.

  5. Stimulus control topography coherence theory: foundations and extensions.

    PubMed

    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.

  6. Engineering microscale topographies to control the cell–substrate 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 cell–substrate 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

  7. 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

  8. 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.

  9. 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

  10. 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 ...

  11. 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

  12. 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

  13. Silk Film Topography Directs Collective Epithelial Cell Migration

    PubMed Central

    Rosenblatt, Mark I.

    2012-01-01

    The following study provides new insight into how surface topography dictates directed collective epithelial cell sheet growth through the guidance of individual cell movement. Collective cell behavior of migrating human corneal limbal-epithelial cell sheets were studied on highly biocompatible flat and micro-patterned silk film surfaces. The silk film edge topography guided the migratory direction of individual cells making up the collective epithelial sheet, which resulted in a 75% increase in total culture elongation. This was due to a 3-fold decrease in cell sheet migration rate efficiency for movement perpendicular to the topography edge. Individual cell migration direction is preferred in the parallel approach to the edge topography where localization of cytoskeletal proteins to the topography’s edge region is reduced, which results in the directed growth of the collective epithelial sheet. Findings indicate customized biomaterial surfaces may be created to direct both the migration rate and direction of tissue epithelialization. PMID:23185573

  14. EAARL coastal topography--North Shore, Lake Pontchartrain, Louisiana, 2010

    USGS Publications Warehouse

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

    2012-01-01

    This DVD contains lidar-derived coastal topography GIS datasets of a portion of the north shore of Lake Pontchartrain, Louisiana. These datasets were acquired on February 28, March 1, and March 5, 2010.

  15. 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.

  16. 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.

  17. 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.

    1985-01-01

    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 constrasts 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.

  18. Asymmetric three-dimensional topography over mantle plumes.

    PubMed

    Burov, Evgueni; Gerya, Taras

    2014-09-01

    The role of mantle-lithosphere interactions in shaping surface topography has long been debated. In general, it is supposed that mantle plumes and vertical mantle flows result in axisymmetric, long-wavelength topography, which strongly differs from the generally asymmetric short-wavelength topography created by intraplate tectonic forces. However, identification of mantle-induced topography is difficult, especially in the continents. It can be argued therefore that complex brittle-ductile rheology and stratification of the continental lithosphere result in short-wavelength modulation and localization of deformation induced by mantle flow. This deformation should also be affected by far-field stresses and, hence, interplay with the 'tectonic' topography (for example, in the 'active/passive' rifting scenario). Testing these ideas requires fully coupled three-dimensional numerical modelling of mantle-lithosphere interactions, which so far has not been possible owing to the conceptual and technical limitations of earlier approaches. Here we present new, ultra-high-resolution, three-dimensional numerical experiments on topography over mantle plumes, incorporating a weakly pre-stressed (ultra-slow spreading), rheologically realistic lithosphere. The results show complex surface evolution, which is very different from the smooth, radially symmetric patterns usually assumed as the canonical surface signature of mantle upwellings. In particular, the topography exhibits strongly asymmetric, small-scale, three-dimensional features, which include narrow and wide rifts, flexural flank uplifts and fault structures. This suggests a dominant role for continental rheological structure and intra-plate stresses in controlling dynamic topography, mantle-lithosphere interactions, and continental break-up processes above mantle plumes. PMID:25186903

  19. Asymmetric three-dimensional topography over mantle plumes.

    PubMed

    Burov, Evgueni; Gerya, Taras

    2014-09-01

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

  20. Review of past and present techniques of measuring corneal topography.

    PubMed

    Fowler, C W; Dave, T N

    1994-01-01

    Various methods of measuring corneal topography are described. The advantages and disadvantages of the principles used in the measurement of corneal shape by the various techniques are discussed. The corneal surface may be described in a number of ways; some researchers have used conic sections while others have used more complex polynomial expressions. Computer algorithms have also been developed to calculate quantitative measures of corneal topography to augment the information obtained from topographical maps. These descriptors are discussed in this article.

  1. Phase contrast in Simultaneous Topography and Recognition imaging.

    PubMed

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

    2009-08-01

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

  2. 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.

  3. 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

  4. Crust rheology, slab detachment and topography

    NASA Astrophysics Data System (ADS)

    Duretz, T.; Gerya, T. V.

    2012-04-01

    The collision between continents following the closure of an ocean can lead to the subduction of continental crust. The introduction of buoyant crust within subduction zones triggers the development of extensional stresses in slabs which eventually result in their detachment. The dynamic consequences of slab detachment affects the development of topography, the exhumation of high-pressure rocks and the geodynamic evolution of collision zones. We employ two-dimensional thermo-mechanical modelling in order to study the importance of crustal rheology on the evolution of spontaneous subduction-collision systems and the occurrence of slab detachment. The modelling results indicate that varying the rheological structure of the crust can results in a broad range of collisional evolutions involving slab detachment, delamination (associated to slab rollback), or the combination of both mechanisms. By enhancing mechanical coupling at the Moho, a strong crust leads to the deep subduction of the crust (180 km). These collisions are subjected to slab detachment and subsequent coherent exhumation of the crust accommodated by eduction (inversion of subduction sense) and thrusting. In these conditions, slab detachment promotes the development of a high (> 4.5 km) and narrow (< 200 km) topographic plateau located in the vicinity of the suture. A contrasting style of collision is obtained by employing a weak crustal rheology. The weak mechanical coupling at the Moho promotes the widespread delamination of the lithosphere, preventing slab detachment to occur. Further shortening leads to buckling and thickening of the crust resulting in the development of topographic bulging on the lower plate. Collisions involving rheologically layered crust are characterised by a decoupling level at mid-crustal depths. These initial condition favours the delamination of the upper crust as well as the deep subduction of the lower crust. These collisions are thus successively affected by delamination

  5. 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

  6. The Ocean Surface Topography Mission (OSTM)

    NASA Astrophysics Data System (ADS)

    Neeck, Steven P.; Vaze, Parag V.

    2008-10-01

    The Ocean Surface Topography Mission (OSTM), also known as Jason-2, will extend into the next decade the continuous climate data record of sea surface height measurements begun in 1992 by the joint NASA/Centre National d'Etudes Spatiales (CNES) TOPEX/Poseidon mission and continued by the NASA/CNES Jason-1 mission in 2001. This multi-decadal record has already helped scientists study the issue of global sea level rise and better understand how ocean circulation and climate change are related. With OSTM, high-precision ocean altimetry has come of age. The mission will serve as a bridge to transition the collection of these measurements to the world's weather and climate forecasting agencies. The agencies will use them for short- and seasonal-to-long-range weather and climate forecasting. OSTM is designed to last at least three years. It will be placed in the same orbit (1,336 kilometers) as Jason-1 and will move along the same ground track at an inclination of 66 degrees to the equator. It will repeat its ground track every 10 days, covering 95 percent of the world's ice-free oceans. A tandem mission between Jason-1 and OSTM will be conducted to further improve tide models in coastal and shallow seas, and to better understand the dynamics of ocean currents and eddies. OSTM is an international and interagency mission developed and operated as a four-party collaboration among NASA, the National Oceanic and Atmospheric Administration (NOAA), CNES, and the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT). CNES is providing the spacecraft, NASA and CNES are jointly providing the payload instruments and NASA is providing the launch vehicle. After completing the onorbit commissioning of the spacecraft, CNES will hand over operation and control of the spacecraft to NOAA. NOAA and EUMETSAT will generate the near-real-time products and distribute them to users. OSTM was launched from Vandenberg Air Force Base, California on June 20, 2008

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

    NASA Astrophysics Data System (ADS)

    Ziethe, Ruth; Benkhoff, Johannes

    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

  8. 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

  9. 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.

  10. Methods for topography artifacts compensation in scanning thermal microscopy.

    PubMed

    Martinek, Jan; Klapetek, Petr; Campbell, Anna Charvátová

    2015-08-01

    Thermal conductivity contrast images in scanning thermal microscopy (SThM) are often distorted by artifacts related to local sample topography. This is pronounced on samples with sharp topographic features, on rough samples and while using larger probes, for example, Wollaston wire-based probes. The topography artifacts can be so high that they can even obscure local thermal conductivity variations influencing the measured signal. Three methods for numerically estimating and compensating for topographic artifacts are compared in this paper: a simple approach based on local sample geometry at the probe apex vicinity, a neural network analysis and 3D finite element modeling of the probe-sample interaction. A local topography and an estimated probe shape are used as source data for the calculation in all these techniques; the result is a map of false conductivity contrast signals generated only by sample topography. This map can be then used to remove the topography artifacts from measured data or to estimate the uncertainty of conductivity measurements using SThM. The accuracy of the results and the computational demands of the presented methods are discussed. PMID:25942752

  11. Corneal topography from spectral optical coherence tomography (sOCT)

    PubMed Central

    Ortiz, Sergio; Siedlecki, Damian; Pérez-Merino, Pablo; Chia, Noelia; de Castro, Alberto; Szkulmowski, Maciej; Wojtkowski, Maciej; Marcos, Susana

    2011-01-01

    We present a method to obtain accurate corneal topography from a spectral optical coherence tomography (sOCT) system. The method includes calibration of the device, compensation of the fan (or field) distortion introduced by the scanning architecture, and image processing analysis for volumetric data extraction, segmentation and fitting. We present examples of three-dimensional (3-D) surface topography measurements on spherical and aspheric lenses, as well as on 10 human corneas in vivo. Results of sOCT surface topography (with and without fan-distortion correction) were compared with non-contact profilometry (taken as reference) on a spherical lens, and with non-contact profilometry and state-of-the art commercial corneal topography instruments on aspheric lenses and on subjects. Corneal elevation maps from all instruments were fitted by quadric surfaces (as well as by tenth-order Zernike polynomials) using custom routines. We found that the discrepancy in the estimated radius of curvature from nominal values in artificial corneas decreased from 4.6% (without fan distortion correction) to 1.6% (after fan distortion correction), and the difference in the asphericity decreased from 130% to 5%. In human corneas, the estimated corneal radius of curvature was not statistically significantly different across instruments. However, a Bland-Altman analysis showed consistent differences in the estimated asphericity and corneal shape between sOCT topographies without fan distortion correction and the rest of the measurements. PMID:22162814

  12. Smoking topography and abstinence in adult female smokers.

    PubMed

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

    2013-12-01

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

  13. Smoking topography and abstinence in adult female smokers

    PubMed Central

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

    2013-01-01

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

  14. Present-day dynamic and residual topography in central Anatolia

    NASA Astrophysics Data System (ADS)

    Uluocak, Ebru Şengül; Pysklywec, Russell; Göğüş, Oğuz H.

    2016-06-01

    The Central Anatolian orogenic plateau is represented by young volcanism, rapid plateau uplift, and distinctive (past and active) tectonic deformation. In this study, we consider observational data in terms of regional present-day geodynamics in the region. The residual topography of Central Anatolia was derived to define the regional isostatic conditions according to Airy isostasy and infer the potential role of "dynamic topography". Two-dimensional thermo-mechanical forward models for coupled mantle-lithosphere flow/deformation were conducted along a N-S directional profile through the region (e.g. northern/Pontides, interior, and southern/Taurides). These models were based on seismic tomography data that provide estimates about the present-day mantle thermal structure beneath the Anatolian plate. We compare the modelling results with calculated residual topography and independent data sets of geological deformation, gravity, and high surface heat flow/widespread geothermal activity. Model results suggest that there is ˜1 km of mantle flow induced dynamic topography associated with the sub-lithospheric flow driven by the seismically-inferred mantle structure. The uprising mantle may have also driven the asthenospheric source of volcanism in the north (e.g. Galatia volcanic province) and the Cappadocia volcanic province in the south while elevating the surface in the last 10 Myrs. Our dynamic topography calculations emphasize the role of vertical forcing under other orogenic plateaux underlain by relatively thin crust and low-density asthenospheric mantle.

  15. Present-day dynamic and residual topography in Central Anatolia

    NASA Astrophysics Data System (ADS)

    Şengül Uluocak, Ebru; Pysklywec, Russell; Göǧüş, Oǧuz H.

    2016-09-01

    The Central Anatolian orogenic plateau is represented by young volcanism, rapid plateau uplift and distinctive (past and active) tectonic deformation. In this study, we consider observational data in terms of regional present-day geodynamics in the region. The residual topography of Central Anatolia was derived to define the regional isostatic conditions according to Airy isostasy and infer the potential role of `dynamic topography'. 2-D thermomechanical forward models for coupled mantle-lithosphere flow/deformation were conducted along an N-S directional profile through the region (e.g. northern/Pontides, interior and southern/Taurides). These models were based on seismic tomography data that provide estimates about the present-day mantle thermal structure beneath the Anatolian plate. We compare the modelling results with calculated residual topography and independent data sets of geological deformation, gravity and high surface heat flow/widespread geothermal activity. Model results suggest that there is ˜1 km of mantle flow induced dynamic topography associated with the sublithospheric flow driven by the seismically inferred mantle structure. The uprising mantle may have also driven the asthenospheric source of volcanism in the north (e.g. Galatia volcanic province) and the Cappadocia volcanic province in the south while elevating the surface in the last 10 Myr. Our dynamic topography calculations emphasize the role of vertical forcing under other orogenic plateaux underlain by relatively thin crust and low-density asthenospheric mantle.

  16. Methods for topography artifacts compensation in scanning thermal microscopy.

    PubMed

    Martinek, Jan; Klapetek, Petr; Campbell, Anna Charvátová

    2015-08-01

    Thermal conductivity contrast images in scanning thermal microscopy (SThM) are often distorted by artifacts related to local sample topography. This is pronounced on samples with sharp topographic features, on rough samples and while using larger probes, for example, Wollaston wire-based probes. The topography artifacts can be so high that they can even obscure local thermal conductivity variations influencing the measured signal. Three methods for numerically estimating and compensating for topographic artifacts are compared in this paper: a simple approach based on local sample geometry at the probe apex vicinity, a neural network analysis and 3D finite element modeling of the probe-sample interaction. A local topography and an estimated probe shape are used as source data for the calculation in all these techniques; the result is a map of false conductivity contrast signals generated only by sample topography. This map can be then used to remove the topography artifacts from measured data or to estimate the uncertainty of conductivity measurements using SThM. The accuracy of the results and the computational demands of the presented methods are discussed.

  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. Mercury's Thermal Evolution, Dynamical Topography and Geoid

    NASA Astrophysics Data System (ADS)

    Ziethe, Ruth; Benkhoff, Johannes

    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

  19. 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.

  20. 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.

  1. Laser-based nanoengineering of surface topographies for biomedical applications

    NASA Astrophysics Data System (ADS)

    Schlie, Sabrina; Fadeeva, Elena; Koroleva, Anastasia; Ovsianikov, Aleksandr; Koch, Jürgen; Ngezahayo, Anaclet; Chichkov, Boris. N.

    2011-04-01

    In this study femtosecond laser systems were used for nanoengineering of special surface topographies in silicon and titanium. Besides the control of feature sizes, we demonstrated that laser structuring caused changes in material wettability due to a reduced surface contact area. These laser-engineered topographies were tested for their capability to control cellular behavior of human fibroblasts, SH-SY5Y neuroblastoma cells, and MG-63 osteoblasts. We found that fibroblasts reduced cell growth on the structures, while the other cell types proliferated at the same rate. These findings make laser-surface structuring very attractive for biomedical applications. Finally, to explain the results the correlation between topography and the biophysics of cellular adhesion, which is the key step of selective cell control, is discussed.

  2. 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.

  3. 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.

  4. Influence of nanophase titania topography on bacterial attachment and metabolism.

    PubMed

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

    2008-01-01

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

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

    PubMed

    Vujović, Dragana; Vučković, Vladan; Curić, Mlađen

    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

  6. 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.

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

    PubMed

    Vujović, Dragana; Vučković, Vladan; Curić, Mlađen

    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 %.

  8. Mulitple Origins of Sand Dune-Topography Interactions on Titan

    NASA Astrophysics Data System (ADS)

    Goggin, H.; Ewing, R. C.; Hayes, A.; Cisneros, J.; Epps, J. C.

    2015-12-01

    The interaction between sand dune patterns and topographic obstacles is a primary signal of sand transport direction in the equatorial region of Saturn's moon, Titan. The streamlined, tear drop appearance of the sand-dune patterns as they wrap around obstacles and a dune-free zone on the east side of many obstacles gives the impression that sand transport is from the west to east at equatorial latitudes. However, the physical mechanism behind the dune-obstacle interaction is not well explained, leaving a gap in our understanding of the equatorial sand transport and implied wind directions and magnitudes on Titan. In order to better understand this interaction and evaluate wind and sand transport direction, we use morphometric analysis of optical images on Earth and Cassini SAR images on Titan combined with analog wind tunnel experiments to study dune-topography interactions. Image analysis is performed in a GIS environment to map spatial variations in dune crestline orientations proximal to obstacles. We also use digital elevation models to and analyze the three-dimensional geometry - height, length, width and slope of the dune-topography relationships on Earth. Preliminary results show that dune patterns are deflected similarly around positive, neutral, or negative topography, where positive topography is greater than the surrounding dune height, neutral topography is at dune height and negative topography is lower than dune heights. In the latter case these are typically intra-dune field playas. The obstacle height, width, slope and wind variability appear to play a primary role in determining if a lee-dune, rather than a dune-free lee-zone, develops. In many cases a dune-free playa with evaporite and mud desiccation polygons forms lee-ward of the obstacle. To support and elaborate on the mapping and spatial characterization of dune-topography interactions, a series of experiments using a wind tunnel were conducted. Wind tunnel experiments examine the formation

  9. Geoid, topography, and convection-driven crustal deformation on Venus

    NASA Technical Reports Server (NTRS)

    Simons, Mark; Hager, Bradford H.; Solomon, Sean C.

    1992-01-01

    High-resolution Magellan images and altimetry of Venus reveal a wide range of styles and scales of surface deformation that cannot readily be explained within the classical terrestrial plate tectonic paradigm. The high correlation of long-wavelength topography and gravity and the large apparent depths of compensation suggest that Venus lacks an upper-mantle low-viscosity zone. A key difference between Earth and Venus may be the degree of coupling between the convecting mantle and the overlying lithosphere. Mantle flow should then have recognizable signatures in the relationships between surface topography, crustal deformation, and the observed gravity field.

  10. Topography of Small Coronae on Venus: Preliminary Overview

    NASA Astrophysics Data System (ADS)

    Kreslavsky, M.; Vdovichenko, R.

    1996-03-01

    We surveyed topography of small coronae on Venus and created a data set of quantitative description of coronae topographic patterns. We failed to arrange all coronae profiles into an evolutionary sequences. We have not found prominent dependences between parameters of corona topography except an obvious trend the smaller corona, the simplier its topographic pattern. There is weak correlation of widths of all ring-like topographic features against corona diameter. The facts evidence that wide diversity of topographic patterns are due to individual peculiarities of corona-forming sources rather than variations of geological settings and ages.

  11. Assessing the quality of topography from stereo-photoclinometry

    NASA Astrophysics Data System (ADS)

    Barnouin, O.; Gaskell, R.; Kahn, E.; Ernst, C.; Daly, M.; Bierhaus, E.; Johnson, C.; Clark, B.; Lauretta, D.

    2014-07-01

    Stereo-photoclinometry (SPC) has been used extensively to determine the shape and topography of various asteroids from image data. This technique will be used as one of two main approaches for determining the shape and topography of the asteroid Bennu, the target of the Origins Spectral Interpretation Resource Identification Security-Regolith Explorer (OSIRIS-REx) mission. The purpose of this study is to evaluate the quality of SPC products derived from the Near-Earth Asteroid Rendezvous (NEAR) mission, whose suite of imaging data resembles that to be collected by OSIRIS-REx. We make use of the NEAR laser range-finder (NLR) to independently assess SPC's accuracy and precision.

  12. 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.

  13. 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.

  14. Topography measurements and applications in ballistics and tool mark identifications*

    PubMed Central

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

    2016-01-01

    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. PMID:27182440

  15. Dynamic topography in subduction zones: insights from laboratory models

    NASA Astrophysics Data System (ADS)

    Bajolet, Flora; Faccenna, Claudio; Funiciello, Francesca

    2014-05-01

    The topography in subduction zones can exhibit very complex patterns due to the variety of forces operating this setting. If we can deduce the theoretical isostatic value from density structure of the lithosphere, the effect of flexural bending and the dynamic component of topography are difficult to quantify. In this work, we attempt to measure and analyze the topography of the overriding plate during subduction compared to a pure shortening setting. We use analog models where the lithospheres are modeled by thin-sheet layers of silicone putty lying on low-viscosity syrup (asthenosphere). The model is shorten by a piston pushing an oceanic plate while a continental plate including a weak zone to localize the deformation is fixed. In one type of experiments, the oceanic plate bends and subducts underneath the continental one; in a second type the two plates are in contact without any trench, and thus simply shorten. The topography evolution is monitored with a laser-scanner. In the shortening model, the elevation increases progressively, especially in the weak zone, and is consistent with expected isostatic values. In the subduction model, the topography is characterized, from the piston to the back-wall, by a low elevation of the dense oceanic plate, a flexural bulge, the trench forming a deep depression, the highly elevated weak zone, and the continental upper plate of intermediate elevation. The topography of the upper plate is consistent with isostatic values for very early stages, but exhibits lower elevations than expected for later stages. For a same amount of shortening of the continental plate, the thickening is the same and the plate should have the same elevation in both types of models. However, comparing the topography at 20, 29 and 39% of shortening, we found that the weak zone is 0.4 to 0.6 mm lower when there is an active subduction. Theses values correspond to 2.6 to 4 km in nature. Although theses values are high, there are of the same order as

  16. 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.

  17. Planarization of topography with spin-on carbon hard mask

    NASA Astrophysics Data System (ADS)

    Noya, Go; Hama, Yusuke; Ishii, Maki; Nakasugi, Shigemasa; Kudo, Takanori; Padmanaban, Munirathna

    2016-03-01

    Spin-on-carbon hard mask (SOC HM) has been used in semiconductor manufacturing since 45nm node as an alternative carbon hard mask process to chemical vapor deposition (CVD). As advancement of semiconductor to 2X nm nodes and beyond, multiple patterning technology is used and planarization of topography become more important and challenging ever before. In order to develop next generation SOC, one of focuses is planarization of topography. SOC with different concepts for improved planarization and the influence of thermal flow temperature, crosslink, film shrinkage, baking conditions on planarization and filling performance are described in this paper.

  18. 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.

  19. 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.

  20. 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.

  1. The interaction of marine fouling organisms with topography of varied scale and geometry: a review.

    PubMed

    Myan, Felicia Wong Yen; Walker, James; Paramor, Odette

    2013-12-01

    Many studies have examined the effects of surface topography on the settlement behaviour of marine organisms and this article reviews these investigations with more emphasis on the effects of topography scale. It has been observed that macro topographies (1-100 mm) are generally favoured by marine fouling taxa and are unsuitable for antifouling applications. This is because macro topographies are usually large enough to fit fouling organisms and provide refuge from dangers in the marine environment. Micro topographies had only limited success at reducing fouling from a wide range of marine taxa. The antifouling performance of micro topographies (1 to ≤ 1000 μm) is dependent on the properties of topography features in terms of symmetry, isotropy, width, length, height/depth, separation distance and average roughness. In terms of the antifouling performance of micro topography, topography geometry may only be of secondary importance in comparison to the size of features itself. It is also noted that hydrodynamic stresses also contribute to the settlement trends of foulers on textured surfaces. Future studies on antifouling topographies should be directed to hierarchical topographies because the mixed topography scales might potentially reduce fouling by both micro and macro organisms. Patterned nano-topographies (1- ≤ 1000 nm) should also be explored because the antifouling mechanisms of these topographies are not yet clear.

  2. 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.

  3. Simultaneous topography and recognition imaging using force microscopy.

    PubMed

    Stroh, Cordula M; Ebner, Andreas; Geretschläger, Manfred; Freudenthaler, Günter; Kienberger, Ferry; Kamruzzahan, A S M; Smith-Gill, Sandra J; Gruber, Hermann J; Hinterdorfer, Peter

    2004-09-01

    We present a method for simultaneously recording topography images and localizing specific binding sites with nm positional accuracy by combining dynamic force microscopy with single molecule recognition force spectroscopy. For this we used lysozyme adsorbed to mica, the functionality of which was characterized by enzyme immunoassays. The topography and recognition images were acquired using tips that were magnetically oscillated during scanning and contained antibodies directed against lysozyme. For cantilevers with low Q-factor (approximately 1 in liquid) driven at frequencies below resonance, the surface contact only affected the downward deflections (minima) of the oscillations, whereas binding of the antibody on the tip to lysozyme on the surface only affected the upwards deflections (maxima) of the oscillations. The recognition signals were therefore well separated from the topographic signals, both in space (Delta z approximately 5 nm) and time (approximately 0.1 ms). Topography and recognition images were simultaneously recorded using a specially designed electronic circuit with which the maxima (U(up)) and the minima (U(down)) of each sinusoidal cantilever deflection period were depicted. U(down) was used for driving the feedback loop to record the height (topography) image, and U(up) provided the data for the recognition image. PMID:15345574

  4. 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.

  5. Shape and Topography of Saturn's Satellites from Imaging Data

    NASA Astrophysics Data System (ADS)

    Gaskell, R. W.; Mastrodemos, N.; Rizk, B.

    2010-12-01

    Detailed global and local digital topographies of eight of Saturn's satellites are being constructed from ensembles of overlapping maplets which completely cover the visible surfaces. Each maplet is a digital representation of a piece of the surface topography and albedo constructed from imaging data with stereophotoclinometry. Multiple images projected onto the maplet provide brightness values at each pixel which are used in a least-squares estimation for slope and relative albedo. The slopes are then integrated to produce the topography solution. The central pixel of each maplet represents a control point, and the ensemble of these points is used in an estimation for their body-fixed locations, the rotational state of the body, and the position and attitude of the spacecraft. Applications of these data products include studies of cratering of icy bodies and the subsequent relaxation of the surface, while detailed shapes for the small, irregular satellites can be used to predict the surface gravity and local slope at high resolution. For a larger satellite, a precise shape determination is important because often the shape was frozen in when the body was in a different rotational state. This enables an analysis of the rotational and orbital histories of these bodies. The high resolution topography yields surface roughness, slopes, overall elevation variations, and fractal character of the surface.

  6. 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

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

  8. 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.

  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. 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.

  11. 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…

  12. Rapid topography mapping of scalar fields: Large molecular clusters

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

    An efficient and rapid algorithm for topography mapping of scalar fields, molecular electron density (MED) and molecular electrostatic potential (MESP) is presented. The highlight of the work is the use of fast function evaluation by Deformed-atoms-in-molecules (DAM) method. The DAM method provides very rapid as well as sufficiently accurate function and gradient evaluation. For mapping the topography of large systems, the molecular tailoring approach (MTA) is invoked. This new code is tested out for mapping the MED and MESP critical points (CP's) of small systems. It is further applied to large molecular clusters viz. (H2O)25, (C6H6)8 and also to a unit cell of valine crystal at MP2/6-31+G(d) level of theory. The completeness of the topography is checked by extensive search as well as applying the Poincaré-Hopf relation. The results obtained show that the DAM method in combination with MTA provides a rapid and efficient route for mapping the topography of large molecular systems.

  13. 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.

  14. EAARL coastal topography-Virginia, post-Nor'Ida, 2009

    USGS Publications Warehouse

    Bonisteel-Cormier, J.M.; Nayegandhi, Amar; Fredericks, Xan; Klipp, E.S.; Nagle, D.B.; Vivekanandan, Saisudha; Wright, C.W.; Sallenger, A.H.; Brock, J.C.

    2011-01-01

    This DVD contains lidar-derived first-surface (FS) and bare-earth (BE) topography GIS datasets of a portion of the Virginia coastline beachface. These datasets were acquired post-Nor'Ida on November 27, 2009, November 29, 2009, and December 1, 2009.

  15. 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

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

    NASA Astrophysics Data System (ADS)

    Sangireddy, Harish; Carothers, Richard A.; Stark, Colin P.; Passalacqua, Paola

    2016-06-01

    Mark Melton in 1957 found that climate, basin morphometry, and surficial variables control drainage density (Dd), but differences observed between field surveyed channels and those mapped on topographic contours or blue lines left doubts on these results. Later, several landscape evolution model and observational studies analyzed the behavior of Dd . However, only a few studies have been performed over a large number of landscapes of different characteristics and have relied on high resolution topography data. We revisit Melton's hypothesis by using meter-resolution digital terrain models (DTMs) in 101 subbasins in the USA. We first propose a dimensionless drainage density (Ddd) metric based on the ratio of likely channelized pixels to total number of basin pixels, which has the advantage of eliminating the computation of the channel network. Our analysis shows that Ddd is a weak scaling function of the input DTM resolution compared to the classic dimensional Dd metric (ratio of total channel length to total basin area). We analyze the correlation of Ddd and mean annual precipitation (MAP) with a Gaussian mixture model which identifies two sub-groups displaying different correlation; negative in arid and semi-arid environments, and positive in humid environments. The transition in correlation is around 1100 ± 100 mm/yr of MAP and is accompanied by the occurrence of thick soil layers and high available water capacity that promote dense vegetation cover (Vcov) and low Ddd . While small variation in Ddd is observed across vegetation types, increasing Vcov corresponds to decreasing Ddd . We also explore the relationship between Ddd and relief R, and Ddd and lithology. Ddd and R are weakly correlated in arid and semi-arid environments, while they have strong positive correlation in humid environments. No significant correlation is found between Ddd and lithology although the results are likely affected by our sample choice.

  17. Impact of lithosphere rheology on the dynamic topography

    NASA Astrophysics Data System (ADS)

    Burov, Evgueni; Gerya, Taras; Koptev, Alexander

    2014-05-01

    Dynamic topography is a key observable signature of the Earth's and planetary (e.g. Venus) mantle dynamics. In general view, it reflects complex mantle flow patterns, and hence is supposed to correlate at different extent with seismic tomography, SKS fast orientations, geodetic velocity fields and geoid anomalies. However, identification of dynamic topography had no systematic success, specifically in the Earth's continents. Here we argue that lithosphere rheology, in particular, rheological stratification of continents, results in modulation of dynamic topography, converting commonly expected long-wavelength/small amplitude undulations into short-wavelength surface undulations with wide amplitude spectrum, superimposed onto "tectonic" topography. These ideas are explored in 3D using unprecedentedly high resolution numerical experiments (grid step size 2-3 km for 1500x1500x600 km computational area) incorporating realistic rheologically stratified lithosphere. Such high resolution is actually needed to resolve small-scale crustal faulting and inter-layer coupling/uncoupling that shape surface topography. The results reveal strikingly discordant, counterintuitive features of 3D dynamic topography, going far beyond the inferences from previous models. In particular, even weak anisotropic tectonic stress field results both in large-scale small-amplitude dynamic topography and in strongly anisotropic short-wavelength (at least in one direction) dynamic topography with wide amplitude range (from 100 to 2000-3000 m), including basins and ranges and large-scale linear normal and strike-slip faults. Even very slightly pre-stressed strong lithosphere yields and localizes deformation much easier , than un-prestressed one, in response to plume impact and mantle flow. The results shed new light on the importance of lithosphere rheology and active role of lithosphere in mantle-lithosphere interactions as well as on the role of mantle flow and far-field stresses in tectonic

  18. Climate dominated topography in a tectonically active mountain range

    NASA Astrophysics Data System (ADS)

    Adams, B. A.; Ehlers, T. A.

    2015-12-01

    Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The broad spatial trend in channel steepness values suggests that the locus of high rock uplift rates is coincident with the rugged range core, in a similar position as high temperature and pressure lithologies, but not in the low lying foothills as has been previously suggested by low-temperature thermochronometry. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns. We demonstrate the same topographic effects are recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on topography makes the argument of mountain range steadiness untenable in significantly glaciated settings. Furthermore, our results suggest that most glaciated Cenozoic ranges are likely still in a mode of readjustment as fluvial systems change topography and erosion rates to equilibrate with rock uplift rates.

  19. Mantle Flow Pattern and Dynamic Topography beneath the Eastern US

    NASA Astrophysics Data System (ADS)

    Liu, S.; King, S. D.; Adam, C. M.; Long, M. D.; Benoit, M. H.; Kirby, E.

    2015-12-01

    The complex tectonic history of the eastern US over the past billion years includes episodes of subduction and rifting associated with two complete cycles of supercontinent assembly and breakup. Both the previous global tomography models (S40RTS, SAVANI, TX2011, GyPSuM, SMEAN) and the analysis of the shear-wave splitting from the broadband seismic stations find a distinct coast-to-inland differentiation pattern in the lithosphere and upper mantle. The Mid-Atlantic Geophysical Integrative Collaboration (MAGIC) includes a dense linear seismic array from the Atlantic coast of Virginia to the western boarder of Ohio, crossing several different tectonic zones. To derive the regional mantle flow pattern along with its surface expression such as dynamic topography and aid the interpretation of the seismic observations, we are building a new geodynamic model based on ASPECT (Advanced Solver for Problems in Earth CovecTion) that uses buoyancy derived from seismic tomography along with realistic lithosphere and sub-lithosphere structure. At present, we use S40RTS and SAVANI tomography models together with the temperature-dependent viscosity to compute the mantle flow and dynamic topography. Beneath the eastern US, the upper mantle flow in our model is primarily parallel to the trend of the Appalachian belt, which is broadly consistent with the direction of the local shear-wave splitting. The dynamic topography results exhibit a coast-to-inland magnitude differentiation along the MAGIC seismic deployment. The numerical tests also show that both the magnitude and pattern of the dynamic topography are quite sensitive to the density perturbation and rigidity of the lithosphere/sub-lithosphere. Our future work involves using other tomography and viscosity models to obtain the mantle flow pattern as well as the resulting dynamic topography and geoid.

  20. 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

  1. Upper-Mantle Flow Driven Dynamic Topography in Eastern Anatolia

    NASA Astrophysics Data System (ADS)

    Sengul Uluocak, Ebru; Pysklywec, Russell; Eken, Tuna; Hakan Gogus, Oguz

    2016-04-01

    Eastern Anatolia is characterized by 2 km plateau uplift -in the last 10 Myrs-, high surface heat flow distribution, shallow Curie-point depth, anomalous gravity field. Seismological observations indicate relatively high Pn and Sn attenuation and significant low seismic velocity anomalies in the region. Moreover, the surface geology is associated predominantly with volcanic rocks in which melt production through mantle upwelling (following lithospheric delamination) has been suggested. It has been long known that the topographic loading in the region cannot be supported by crustal thickness (~45 km) based on the principle of Airy isostasy. Recent global geodynamic studies carried out for evaluating the post-collisional processes imply that there is an explicit dynamic uplift in Eastern Anatolia and its adjacent regions. In this study we investigate the instantaneous dynamic topography driven by 3-D upper-mantle flow in Eastern Anatolia. For this purpose we conducted numerous thermo-mechanical models using a 2-D Arbitrary Lagrangian Eulerian (ALE) finite element method. The available P-wave tomography data extracted along 10 profiles were used to obtain depth-dependent density anomalies in the region. We present resulting dynamic topography maps and estimated 3D mantle flow velocity vectors along these 2-D cross sections for each profile. The residual topography based on crustal thickness and observed topography was calculated and compared with other independent datasets concerning geological deformation and dynamic topography predictions. The results indicate an upper mantle driven dynamic uplift correlated with the under-compensated characteristic in Eastern Anatolia. We discuss our results combined with 3D mantle flow by considering seismic anisotropy studies in the region. Initial results indicate that high dynamic uplift and the localized low Pn velocities in concurrence with Pn anisotropy structures show nearly spatial coherence in Eastern Anatolia.

  2. 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

  3. 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.

  4. 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.

  5. Mola's First Observations of the Southern Hemisphere Topography of Mars

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

    Towards the end of February 1999, the Mars Global Surveyor (MGS) spacecraft is expected to enter a near-circular polar orbit around Mars at an altitude of about 400 km. At this time the Mars Orbiter Laser Altimeter (MOLA) will begin near-continuous operation and acquire topography of the full planet. The initial areas of study will be concentrated in the southern hemisphere with particular interest in the polar region near the targeted landing site of the Mars Polar Lander. In addition to topography, MOLA matched filter pulse width data will be used to assess foot-print-scale surface roughness in the region. Such observations will also be applied in future studies for assessment of the Mars '01 landing site in the latitude range 15 degrees south to 5 degrees north.

  6. Fluid flow over arbitrary bottom topography in a channel

    NASA Astrophysics Data System (ADS)

    Panda, Srikumar

    2016-05-01

    In this paper, two-dimensional free surface potential flow over an arbitrary bottom in a channel is considered to analyze the behavior of the free surface profile using linear theory. It is assumed that the fluid is inviscid, incompressible and flow is irrotational. Perturbation analysis in conjunction with Fourier transform technique is employed to determine the first order corrections of some important physical quantities such as free surface profile, velocity potential, etc. From the practical point of view, one arbitrary bottom topography is considered to determine the free surface profile since the free surface profile depends on the bottom topography. It is found that the free surface profile is oscillatory in nature, representing a wave propagating downstream and no wave upstream.

  7. Biomimetic topography and chemistry control cell attachment to amyloid fibrils.

    PubMed

    Reynolds, Nicholas P; Charnley, Mirren; Bongiovanni, Marie N; Hartley, Patrick G; Gras, Sally L

    2015-05-11

    Networks of nanoscale fibrous coatings made from self-assembled peptides are promising candidates for biomaterials that can promote the growth of mammalian cells. One particularly attractive feature is the possibility of adding biofunctional sequences to peptides to promote cell attachment. We deconvolute the topographic and chemical effects of nanoscale fibrils on cells by depositing a plasma polymer film on TTR1-based fibrils decorated with a range of cell adhesive chemistries (RGD and cycloRGDfK), producing a surface that retains the nanoscale fibrous topography of surface-bound fibrils but lacks the fibril surface chemistry. The surface topography was found to influence cell toxicity and spreading, and the fibril surface chemistry influenced cell attachment and spreading. This study highlights the importance of considering both the chemical and physical features of novel biomaterials and illustrates the use of plasma polymer deposition as a tool for examining the relationship between amyloid fibril structure and function. PMID:25871317

  8. 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.

  9. 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.

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

    DOEpatents

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

    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.

  11. 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.

  12. Stochastic variability of oceanic flows above topography anomalies

    NASA Astrophysics Data System (ADS)

    Venaille, A.; Le Sommer, J.; Molines, J.-M.; Barnier, B.

    2011-08-01

    We describe a stochastic variability mechanism which is genuinely internal to the ocean, i.e., not due to fluctuations in atmospheric forcing. The key ingredient is the existence of closed contours of bottom topography surrounded by a stirring region of enhanced eddy activity. This configuration leads to the formation of a robust but highly variable vortex above the topography anomaly. The vortex dynamics integrates the white noise forcing of oceanic eddies into a red noise signal for the large scale volume transport of the vortex. The strong interannual fluctuations of the transport of the Zapiola anticyclone (˜100 Sv) in the Argentine basin are argued to be partly due to such eddy-driven stochastic variability, on the basis of a 310 years long simulation of a comprehensive global ocean model run driven by a repeated-year forcing.

  13. [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.

  14. 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.

  15. Venusian highlands - Geoid to topography ratios and their implications

    NASA Technical Reports Server (NTRS)

    Smrekar, Suzanne E.; Phillips, Roger J.

    1991-01-01

    Geoid-to-topography ratios (GTRs) are estimated for 12 Venusian highland features to allow comparison with convection calculations and with terrestrial data of oceanic hot spots, swells, and plateaus. The geoid is estimated in the wavenumber domain from the isostatic formula, using the topography and the apparent depths isostatic compensation (ADC) for each region. In the space domain, the GTR is equal to the least squares slope of the linear fit of the geoid to the topograpy. The resulting GTR range is 7-31 m/km, which is much higher than terrestrial oceanic values (-1 to 5 m/km). The features fall into two distinct groups, one with a GTR range of 7-13 m/km, and one with a range of 19-25 m/km. A model for thermal thinning of a 100-km-thick lithosphere fits all values in the lower GTR group to within one standard deviation.

  16. Geoid, topography, and convection-driven crustal deformation on Venus

    NASA Technical Reports Server (NTRS)

    Simons, Mark; Hager, Bradford H.; Solomon, Sean C.

    1993-01-01

    High-resolution Magellan images and altimetry of Venus reveal a wide range of styles and scales of surface deformation that cannot readily be explained within the classical terrestrial plate tectonic paradigm. The high correlation of long-wavelength topography and gravity and the large apparent depths of compensation suggest that Venus lacks an upper-mantle low-viscosity zone. A key difference between Earth and Venus may be the degree of coupling between the convecting mantle and the overlying lithosphere. Mantle flow should then have recognizable signatures in the relationships between the observed surface topography, crustal deformation, and the gravity field. Therefore, comparison of model results with observational data can help to constrain such parameters as crustal and thermal boundary layer thicknesses as well as the character of mantle flow below different Venusian features. We explore in this paper the effects of this coupling by means of a finite element modelling technique.

  17. Shaded relief map of US topography from digital elevations

    USGS Publications Warehouse

    Pike, R.J.; Thelin, G.P.

    1989-01-01

    Much geologic and geophysical information that lies encoded within land surface form can be revealed by image processing large files of digitized elevations in fast machines and mapping the results. This convergence of computers, analytic software, data, and output devices has created exciting opportunities for automating the numerical and spatial study of topography. One recent result is the accompanying shaded relief map of the conterminous 48 states. -from Authors

  18. Accurate source location from waves scattered by surface topography

    NASA Astrophysics Data System (ADS)

    Wang, Nian; Shen, Yang; Flinders, Ashton; Zhang, Wei

    2016-06-01

    Accurate source locations of earthquakes and other seismic events are fundamental in seismology. The location accuracy is limited by several factors, including velocity models, which are often poorly known. In contrast, surface topography, the largest velocity contrast in the Earth, is often precisely mapped at the seismic wavelength (>100 m). In this study, we explore the use of P coda waves generated by scattering at surface topography to obtain high-resolution locations of near-surface seismic events. The Pacific Northwest region is chosen as an example to provide realistic topography. A grid search algorithm is combined with the 3-D strain Green's tensor database to improve search efficiency as well as the quality of hypocenter solutions. The strain Green's tensor is calculated using a 3-D collocated-grid finite difference method on curvilinear grids. Solutions in the search volume are obtained based on the least squares misfit between the "observed" and predicted P and P coda waves. The 95% confidence interval of the solution is provided as an a posteriori error estimation. For shallow events tested in the study, scattering is mainly due to topography in comparison with stochastic lateral velocity heterogeneity. The incorporation of P coda significantly improves solution accuracy and reduces solution uncertainty. The solution remains robust with wide ranges of random noises in data, unmodeled random velocity heterogeneities, and uncertainties in moment tensors. The method can be extended to locate pairs of sources in close proximity by differential waveforms using source-receiver reciprocity, further reducing errors caused by unmodeled velocity structures.

  19. Terrain topography measurement using multipass polarimetric synthetic aperture radar data

    NASA Astrophysics Data System (ADS)

    Schuler, Dale L.; Lee, Jong-Sen; Ainsworth, Thomas L.; Grunes, Mitchell R.

    2000-05-01

    A method has been investigated for the measurement of topography using airborne fully polarimetric synthetic aperture radar (SAR) data. Terrain slopes in both the range and azimuthal directions have been estimated using multipass flight geometries. Using these slope values, the Poisson equation was then solved to create a Digital Elevation Model (DEM) of the terrain topography. The method measures polarimetric orientation angles which are then converted into terrain slopes in the azimuthal direction. The conversion of these orientation angles into terrain slopes requires additional knowledge of the radar look angle and the range direction terrain slopes. The solution for slopes is, therefore, a problem coupled between the range and azimuthal directions. For specialized multipass flight geometries these orthogonal terrain slopes are solved for, and maps of terrain slopes are produced. In particular, the processing of two-pass orthogonal and two-pass antiparallel (headings Θ and Θ+ 180°) NASA - Jet Propulsion Laboratory airborne SAR data sets has been carried out for an area in central California. When orthogonal slopes are derived using either of these data sets, a digital elevation model may be generated. The L band, polarimetric SAR (POLSAR) DEM created by this solution is compared to a coregistered C band, interferometric SAR (IFSAR) DEM. Similar comparisons are made for terrain slopes in the azimuthal - range directions which are generated by the POLSAR and IFSAR elevation data. The polarimetric SAR, operating from an aircraft, or satellite, in a strip-mapping mode, is capable of measuring terrain topography for large areas provided that phase-preserving fully polarimetric data are taken. Polarimetric SAR data are also widely used for studies of crop classification, surface roughness, biomass density, and soil moisture content. All of these studies are adversely affected by scattering changes attributable to topography. The technique investigated here

  20. 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.

  1. 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

  2. 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

  3. 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

  4. 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

  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. Unraveling topography around subduction zones from laboratory models

    NASA Astrophysics Data System (ADS)

    Husson, Laurent; Guillaume, Benjamin; Funiciello, Francesca; Faccenna, Claudio; Royden, Leigh H.

    2012-03-01

    The relief around subduction zones results from the interplay of dynamic processes that may locally exceed the (iso)static contributions. The viscous dissipation of the energy in and around subduction zones is capable of generating kilometer scale vertical ground movements. In order to evaluate dynamic topography in a self-consistent subduction system, we carried out a set of laboratory experiments, wherein the lithosphere and mantle are simulated by means of Newtonian viscous materials, namely silicone putty and glucose syrup. Models are kept in their most simple form and are made of negative buoyancy plates, of variable width and thickness, freely plunging into the syrup. The surface of the model and the top of the slab are scanned in three dimensions. A forebulge systematically emerges from the bending of the viscous plate, adjacent to the trench. With a large wavelength, dynamic pressure offsets the foreside and backside of the slab by ~ 500 m on average. The suction, that accompanies the vertical descent of the slab depresses the surface on both sides. At a distance equal to the half-width of the slab, the topographic depression amounts to ~ 500 m on average and becomes negligible at a distance that equals the width of the slab. In order to explore the impact of slab rollback on the topography, the trailing edge of the plates is alternatively fixed to (fixed mode) and freed from (free mode) the end wall of the tank. Both the pressure and suction components of the topography are ~ 30% lower in the free mode, indicating that slab rollback fosters the dynamic subsidence of upper plates. Our models are compatible with first order observations of the topography around the East Scotia, Tonga, Kermadec and Banda subduction zones, which exhibit anomalous depths of nearly 1 km as compared to adjacent sea floor of comparable age.

  7. 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.

  8. Influence of topography on tropical African vegetation coverage

    NASA Astrophysics Data System (ADS)

    Jung, Gerlinde; Prange, Matthias; Schulz, Michael

    2016-04-01

    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.

  9. 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

  10. MOLA Topography of the Crustal Dichotomy Boundary Zone, Mars

    NASA Technical Reports Server (NTRS)

    Frey, Herbert V.; E. H., Susan; H., James

    1998-01-01

    Mars Orbiter Laser Altimeter (MOLA) profiles frequently cross the crustal dichotomy boundary where the transition zone (TZ) between cratered highland terrain (CT) and lowland smooth plains (SP) is marked by mesas and knobby terrain. The detailed topographic character of the boundary zone is longitudinally variable, as is the geomorphology of the TZ. Some portions of the boundary are associated with an outer ring of the Utopia impact basin; MOLA topography is consistent with this. The regional character of the boundary topography is a 2-4 km step function from nearly flat SP to almost as flat CT. This rise has a regional slope of 1-2 degrees, 50-100 times that of the Cr and SP away from TZ, which suggests a significant change in crustal properties (thickness, composition or both) across the TZ. The overall topography is very similar to that at some passive continent-oceanic crustal margins on the Earth, with the seafloor allowed to adjust upward after removal of the overlying water. A possible temporal constraint on the CT/SP elevation difference comes from two MOLA profiles which pass through two large (150 km diameter) craters located at the boundary in Aeolis. The N and S rims of the more degraded crater are at the same elevation; north of the N rim the topography drops by greater than 2 km to the floor of the TZ. This crater predates the elevation offset between CT and TZ floor. The better preserved crater (Gale) has a N rim 2 km lower than its S rim, and appears to have been emplaced on a pre-existing regional slope of about I degree. Gale probably post- dates the elevation difference between CT and TZ floor. Based on the stratigraphy of the units in which these craters are found, the elevation difference appears to have been in place in the Mid to Late Noachian.

  11. Characterizing Cratering at the Iapetus Equatorial Ridge using Stereo Topography

    NASA Astrophysics Data System (ADS)

    Persaud, D. M.

    2015-12-01

    Since the arrival of the Cassini probe to the Saturnian system in 2004, the flattened shape and extreme equatorial ridge of the moon Iapetus have posed a number of questions regarding its geophysical evolution. Current models suggest either tidal despinning or a collapsed ring system formed the ridge, with 26Al decay serving as an additional heating mechanism and warm ice or liquid water beneath a thick lithosphere potentially allowing for large-scale topography and deformation to occur (Sandwell and Schubert 2010). Structure at the ridge itself provides further questions in understanding the deformation of Iapetus at its equator. Persaud and Phillips (2014) use stereo topography to present a trend of crater relaxation and crater diameter that suggests a secondary heating event has relaxed younger, smaller craters focused at this region. The extreme slopes along the ridge, however, complicate understanding the order of events that have occurred on Iapetus, including ridge formation, crater relaxation, secondary thermal events, and mass wasting. We use topographic profiles of Iapetus impact craters extracted from digital elevation models (DEMs) constructed with stereo images from the Cassini ISS Instrument to characterize crater complexity and transition diameters versus crater floor geometry, proximity to the equatorial ridge, and relaxation percentage. We then use these results to begin to develop a geometric model of events at the ridge on Iapetus to understand its deformation history. We will present results and discussion of using stereo topography for these analyses. References: Sandwell, D., and G. Schubert. A contraction model for the flattening and equatorial ridge of Iapetus, Icarus 210, 817-822, 2010. Persaud, D.M., and C.B. Phillips. Methods of Estimating Initial Crater Depths on Icy Satellites using Stereo Topography, AGU Fall Meeting 2014, abstract 17043. This work was supported by the 2015 NASA Ames Academy for Space Exploration.

  12. X-ray topography utilizing non-equatorial reflections

    NASA Astrophysics Data System (ADS)

    Kingman, P. W.

    1987-03-01

    The principal thrust of X-ray topography has been toward the study of general dislocation arrangements in quite perfect crystals. Since the early work of Barrett and Honeycombe there has been relatively little interest in deformation structures; at least in part because of the difficulty of extracting useful quantitative information about the geometry from topographs. This paper describes the general geometry of back reflection topography and shows how a systematic exploitation of the back reflection geometry can be used to maximize the information which can be obtained and optimizes the diffraction geometry for any given Bragg reflection. A camera design based upon this general approach is described, as well some specific procedures for its utilization. The basic approach to back reflection topography can be applied to any topographic arrangement. Since the present camera was intended for the study of macrostructures of crystals with high dislocation densities, it was designed to image large sample areas at low resolution. The basic analysis and procedures apply equally well to any back reflection technique. The possibility of effectively nonequatorial reflections greatly enhances the power and flexibility of the method.

  13. Design consideration and performance analysis of OCT-based topography

    NASA Astrophysics Data System (ADS)

    Meemon, Panomsak; Yao, Jianing; Rolland, Jannick P.

    2014-03-01

    We report a study on design consideration and performance analysis of OCT-based topography by tracking of maximum intensity at each layer's interface. We demonstrate that, for a given stabilized OCT system, a high precision and accuracy of OCT-based layers and thickness topography in the order of tens nanometer can be achieved by using a technique of maximum amplitude tracking. The submicron precision was obtained by over sampling through the FFT of the acquired spectral fringes but was eventually limited by the system stability. Furthermore, we report characterization of a precision, repeatability, and accuracy of the surfaces, sub-surfaces, and thickness topography using our optimized FD-OCT system. We verified that for a given stability of our OCT system, precision of the detected position of signal's peak of down to 20 nm was obtained. In addition, we quantified the degradation of the precision caused by sensitivity fall-off over depth of FD-OCT. The measured precision is about 20 nm at about 0.1 mm depth, and degrades to about 80 nm at 1 mm depth, a position of about 10 dB sensitivity fall-off. The measured repeatability of thickness measurements over depth was approximately 0.04 micron. Finally, the accuracy of the system was verified by comparing with a digital micrometer gauging.

  14. 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.

  15. Topography and instability of monolayers near domain boundaries

    SciTech Connect

    Diamant, H.; Witten, T. A.; Ege, C.; Gopal, A.; Lee, K. Y. C.

    2001-06-01

    We theoretically study the topography of a biphasic surfactant monolayer in the vicinity of domain boundaries. The differing elastic properties of the two phases generally lead to a nonflat topography of {open_quotes}mesas,{close_quotes} where domains of one phase are elevated with respect to the other phase. The mesas are steep but low, having heights of up to 10 nm. As the monolayer is laterally compressed, the mesas develop overhangs and eventually become unstable at a surface tension of about K({delta}c{sub 0}){sup 2} ({delta}c{sub 0} being the difference in spontaneous curvature and K a bending modulus). In addition, the boundary is found to undergo a topography-induced rippling instability upon compression, if its line tension is smaller than about K{delta}c{sub 0}. The effect of diffuse boundaries on these features and the topographic behavior near a critical point are also examined. We discuss the relevance of our findings to several experimental observations related to surfactant monolayers: (i) small topographic features recently found near domain boundaries; (ii) folding behavior observed in mixed phospholipid monolayers and model lung surfactants; (iii) roughening of domain boundaries seen under lateral compression; (iv) the absence of biphasic structures in tensionless surfactant films.

  16. 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

  17. 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.

  18. EAARL Topography-Sagamore Hill National Historic Site

    USGS Publications Warehouse

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

    2007-01-01

    This Web site contains lidar-derived bare earth (BE) and first return (FR) topography maps and GIS files for the Sagamore Hill National Historic Site. 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, Florida, 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 costal resource managers.

  19. 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

  20. Lithosphere delamination and topography evolution in collisional orogens

    NASA Astrophysics Data System (ADS)

    Li, Z. H.; Liu, M.; Gerya, T.

    2015-12-01

    Systematic high-resolution thermo-mechanical numerical models are conducted in order to better understand the behavior of deep mantle lithosphere and surface topography response during continental collision. In the models with similar rheological properties for the pro- (subducting) and retro- (overriding) continental plates, subduction mode is preferred, with localized topography uplift and mountain building. However, if the effective viscosities of the retro-plate are decreased, then delamination of the lithospheric mantle may occur there, which results in large-scale topography buildup and plateau formation. Several other factors that may also influence the delamination dynamics are further investigated, e.g., plastic weakening of the lithospheric mantle, density contrast between the lithospheric and asthenospheric mantle, convergence velocity, as well as the possible lower crust eclogitization effects. Based on the series of numerical simulations, the delamination processes in collisional orogens are summarized into three modes: (1) pro-plate delamination, (2) retro-plate delamination, and (3) a transitional double-plates (both the pro- and retro-plate) delamination. The controlling factors, as well as the geological applications in nature, of the variable delamination modes are also discussed.

  1. Surface topography and wetting modifications of PEEK for implant applications.

    PubMed

    Akkan, Cagri Kaan; Hammadeh, Mohammed Eid; May, Alexander; Park, Hai-Woong; Abdul-Khaliq, Hashim; Strunskus, Thomas; Aktas, Oral Cenk

    2014-09-01

    Polyetheretherketone (PEEK) is considered as a substitute for metallic implant materials due to its extremely low elastic modulus (3-4 GPa). Despite its good mechanical properties, PEEK exhibits a slow integration with the bone tissue due to its relatively inert surface and low biocompatibility. We introduced a dual modification method, which combines the laser and plasma surface treatments to achieve hierarchically patterned PEEK surfaces. While the plasma treatment leads to nanotopography, the laser treatment induces microstructures over the PEEK surface. On the other hand, plasma and laser treatments induce inhomogeneity in the surface chemistry in addition to the tailored surface topography. Therefore, we coated the structured PEEK surfaces with a thin alumina layer by pulsed laser deposition (PLD) to get identical surface chemistry on each substrate. Such alumina-coated PEEK surfaces are used as a model to investigate the effect of the surface topography on the wetting independent from the surface chemistry. Prepared surfaces bring advantages of enhanced wetting, multiscaled topography, proven biocompatibility (alumina layer), and low elastic modulus (PEEK as substrate), which together may trigger the use of PEEK in bone and other implant applications.

  2. Glacial reorganization of topography in a tectonically active mountain range

    NASA Astrophysics Data System (ADS)

    Adams, Byron; Ehlers, Todd

    2016-04-01

    Tests of the interactions between tectonic and climate forcing on Earth's topography often focus on the concept of steady-state whereby processes of rock deformation and erosion are opposing and equal. However, when conditions change such as the climate or tectonic rock uplift, then surface processes act to restore the balance between rock deformation and erosion by adjusting topography. Most examples of canonical steady-state mountain ranges lie within the northern hemisphere, which underwent a radical change in the Quaternary due to the onset of widespread glaciation. The activity of glaciers changed erosion rates and topography in many of these mountain ranges, which likely violates steady-state assumptions. With new topographic analysis, and existing patterns of climate and rock uplift, we explore a mountain range previously considered to be in steady-state, the Olympic Mountains, USA. The details of our analysis suggest the dominant topographic signal in the Olympic Mountains is a spatial, and likely temporal, variation in erosional efficiency dictated by orographic precipitation, and Pleistocene glacier ELA patterns, and not tectonic rock uplift rates. Alpine glaciers drastically altered the relief structure of the Olympic Mountains. The details of these relief changes are recorded in channel profiles as overdeepenings, reduced slopes, and associated knickpoints. We find the position of these relief changes within the orogen is dependent on the position of the Pleistocene ELA. While alpine glaciers overdeepened valleys in regions near the Pleistocene ELA (which has a tendency to increase relief), headward erosion of west and north flowing glacier systems captured significant area from opposing systems and caused drainage divide lowering. This divide lowering reduced relief throughout the range. We demonstrate similar topographic effects recorded in the basin hypsometries of other Cenozoic mountain ranges around the world. The significant glacial overprint on

  3. Core Mantle Boundary Topography and Lowermost Mantle Heterogeneity

    NASA Astrophysics Data System (ADS)

    Sze, E. K.; Karason, H.; van der Hilst, R. D.

    2001-05-01

    The core-mantle boundary (CMB) separates the solid silicate mantle and the liquid iron-nickel outer core and marks the strongest contrasts in density and viscosity within the Earth. Knowledge of CMB topography and heterogeneity pattern above it is key for the understanding of many geodynamic processes. In this study, we use P, PcP, PKPab, PKPbc, PKPdf, PKKP, and Pdiff residual travel times to constrain lateral variations in the depth to the core-mantle boundary (CMB) and in lowermost mantle P-wavespeed. In a first experiment, PcP, PKPab, PKPbc, PKPdf, and PKKP data from Engdahl et al. (BSSA, 1998) were corrected for mantle structure (Karason & Van der Hilst, JGR, 2001 - KH2001) and inner-core anisotropy (Su & Dziewonski, JGR, 1995) before being inverted for variations in CMB depth. The spherical averages of all inverted topographic models suggest that the actual CMB radius is slightly smaller than in the Earth reference model used (ak135). These inversions yield amplitude variations of up to 5 km for PcP, PKPab, PKPbc, and PKKP and 13 km for PKPdf, which is larger than the CMB undulations inferred in geodetic studies. Moreover, the PcP results are not readily consistent with the topography models inferred from the core refracted (PKP and PKKP) waves. These discrepancies suggest that the travel-time residuals cannot be explained by topography alone. Anisotropy and outer core heterogeneity could play a role, and despite the use of P, PKP, and Pdiff data the wavespeed perturbations in KH2001 may be too small to fully account for the trade off between volumetric heterogeneity and CMB. In a second experiment we explored the latter. We applied corrections for mantle structure outside a basal 290-thick layer and inverted all data for both CMB topography and volumetric heterogeneity within this layer. This reduces the amplitude of CMB topography to 1.7 km and yields velocity variations of +/- 5%. The long-wavelength pattern of the velocity model is similar to that of KH

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. Isostatic and dynamic support of high topography on a North Atlantic passive margin

    NASA Astrophysics Data System (ADS)

    Pedersen, Vivi K.; Huismans, Ritske S.; Moucha, Robert

    2016-07-01

    Substantial controversy surrounds the origin of high topography along passive continental margins. Here we focus on the well-documented elevated passive margin in southwestern Scandinavia, and quantify the relative contributions of crustal isostasy and dynamic topography in controlling the present topography. We find that majority of the topography is compensated by the crustal structure, suggesting a topographic age that is in accord with the 400 Myr old Caledonian orogenesis. In addition, we propose that dynamic uplift of ∼300 m has rejuvenated existing topography locally in the coastal region over the last 10 Myr. Such uplift, combined with a general sea level fall, can help explain a variety of observations that have traditionally been interpreted in favor of a peneplain uplift model. We conclude that high topography along the Scandinavian margin cannot represent remnants of a peneplain uplifted within the last 20 Myr. The topography must have been high since the Caledonian orogeny.

  11. Effects of soil fertility and topography on tree growth in subtropical forest ecosystems

    NASA Astrophysics Data System (ADS)

    Seitz, Steffen; Goebes, Philipp; Kühn, Peter; Schmidt, Karsten; Song, Zhengshan; Scholten, Thomas

    2016-04-01

    roles. Nevertheless, soil acidity and a high proportion of Al on the exchange complex affected tree height even after only 1-2 years growth. Hence, our study showed that forest nutrition is coupled to a recycling of litter nutrients and does not only depend on subsequent supply of nutrients from the mineral soil. Besides soil fertility, topography affected tree height. We found that especially MCCA as indicator of water availability affected tree growth at small-scale as well as aspect. Overall, our synthesis showed that topographic heterogeneity lead to ecological gradients across geomorphological positions. In this respect, small-scale soil-plant interactions in a young forest can serve as a driver for the future development of vegetation and biodiversity control on soil fertility. In addition, it shows that terrain attributes should be accounted for in ecological research.

  12. 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

  13. 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, Titan’s 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 Titan’s 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

  14. 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).

  15. Management intensity and topography determined plant diversity in vineyards.

    PubMed

    Nascimbene, Juri; Marini, Lorenzo; Ivan, Diego; Zottini, Michela

    2013-01-01

    Vineyards are amongst the most intensive forms of agriculture often resulting in simplified landscapes where semi-natural vegetation is restricted to small scattered patches. However, a tendency toward a more sustainable management is stimulating research on biodiversity in these poorly investigated agro-ecosystems. The main aim of this study was to test the effect on plant diversity of management intensity and topography in vineyards located in a homogenous intensive hilly landscape. Specifically, this study evaluated the role of slope, mowing and herbicide treatments frequency, and nitrogen supply in shaping plant diversity and composition of life-history traits. The study was carried out in 25 vineyards located in the area of the Conegliano-Valdobbiadene DOCG (Veneto, NE Italy). In each vineyard, 10 plots were placed and the abundance of all vascular plants was recorded in each plot. Linear multiple regression was used to test the effect of management and topography on plant diversity. Management intensity and topography were both relevant drivers of plant species diversity patterns in our vineyards. The two most important factors were slope and mowing frequency that respectively yielded positive and negative effects on plant diversity. A significant interaction between these two factors was also demonstrated, warning against the detrimental effects of increasing mowing intensity on steep slope where plant communities are more diverse. The response of plant communities to mowing frequency is mediated by a process of selection of resistant growth forms, such in the case of rosulate and reptant species. The other two management-related factors tested in this study, number of herbicide treatments and N fertilization, were less influential. In general, our study corroborates the idea that some simple changes in farming activities, which are compatible with grape production, should be encouraged for improving the natural and cultural value of the landscape by

  16. Accurate source location from P waves scattered by surface topography

    NASA Astrophysics Data System (ADS)

    Wang, N.; Shen, Y.

    2015-12-01

    Accurate source locations of earthquakes and other seismic events are fundamental in seismology. The location accuracy is limited by several factors, including velocity models, which are often poorly known. In contrast, surface topography, the largest velocity contrast in the Earth, is often precisely mapped at the seismic wavelength (> 100 m). In this study, we explore the use of P-coda waves generated by scattering at surface topography to obtain high-resolution locations of near-surface seismic events. The Pacific Northwest region is chosen as an example. The grid search method is combined with the 3D strain Green's tensor database type method to improve the search efficiency as well as the quality of hypocenter solution. The strain Green's tensor is calculated by the 3D collocated-grid finite difference method on curvilinear grids. Solutions in the search volume are then obtained based on the least-square misfit between the 'observed' and predicted P and P-coda waves. A 95% confidence interval of the solution is also provided as a posterior error estimation. We find that the scattered waves are mainly due to topography in comparison with random velocity heterogeneity characterized by the von Kάrmάn-type power spectral density function. When only P wave data is used, the 'best' solution is offset from the real source location mostly in the vertical direction. The incorporation of P coda significantly improves solution accuracy and reduces its uncertainty. The solution remains robust with a range of random noises in data, un-modeled random velocity heterogeneities, and uncertainties in moment tensors that we tested.

  17. 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.

  18. Dynamic topography and the Cenozoic carbonate compensation depth

    NASA Astrophysics Data System (ADS)

    Campbell, S. M.; Moucha, R.; Raymo, M. E.; Derry, L. A.

    2015-12-01

    The carbonate compensation depth (CCD), the ocean depth at which the calcium carbonate accumulation rate goes to zero, can provide valuable insight into climatic and weathering conditions over the Cenozoic. The paleoposition of the CCD can be inferred from sediment core data. As the carbonate accumulation rate decreases linearly with depth between the lysocline and CCD, the CCD can be calculated using a linear regression on multiple sediment cores with known carbonate accumulation rates and paleodepths. It is therefore vital to have well-constrained estimates of paleodepths. Paleodepths are typically calculated using models of thermal subsidence and sediment loading and compaction. However, viscous convection-related stresses in the mantle can warp the ocean floor by hundreds of meters over broad regions and can also vary significantly over millions of years. This contribution to paleobathymetry, termed dynamic topography, can be calculated by modeling mantle flow backwards in time. Herein, we demonstrate the effect dynamic topography has on the inference of the late Cenozoic CCD with an example from the equatorial Pacific, considering sites from IODP Expeditions 320/321. The equatorial Pacific, given its large size and high productivity, is closely tied to the global carbon cycle. Accordingly, long-term changes in the equatorial Pacific CCD can be considered to reflect global changes in weathering fluxes and the carbon cycle, in addition to more regional changes in productivity and thermohaline circulation. We find that, when the dynamic topography contribution to bathymetry is accounted for, the equatorial Pacific CCD is calculated to be appreciably shallower at 30 Ma than previous estimates would suggest, implying a greater deepening of the Pacific CCD over the late Cenozoic.

  19. Management Intensity and Topography Determined Plant Diversity in Vineyards

    PubMed Central

    Nascimbene, Juri; Marini, Lorenzo; Ivan, Diego; Zottini, Michela

    2013-01-01

    Vineyards are amongst the most intensive forms of agriculture often resulting in simplified landscapes where semi-natural vegetation is restricted to small scattered patches. However, a tendency toward a more sustainable management is stimulating research on biodiversity in these poorly investigated agro-ecosystems. The main aim of this study was to test the effect on plant diversity of management intensity and topography in vineyards located in a homogenous intensive hilly landscape. Specifically, this study evaluated the role of slope, mowing and herbicide treatments frequency, and nitrogen supply in shaping plant diversity and composition of life-history traits. The study was carried out in 25 vineyards located in the area of the Conegliano-Valdobbiadene DOCG (Veneto, NE Italy). In each vineyard, 10 plots were placed and the abundance of all vascular plants was recorded in each plot. Linear multiple regression was used to test the effect of management and topography on plant diversity. Management intensity and topography were both relevant drivers of plant species diversity patterns in our vineyards. The two most important factors were slope and mowing frequency that respectively yielded positive and negative effects on plant diversity. A significant interaction between these two factors was also demonstrated, warning against the detrimental effects of increasing mowing intensity on steep slope where plant communities are more diverse. The response of plant communities to mowing frequency is mediated by a process of selection of resistant growth forms, such in the case of rosulate and reptant species. The other two management-related factors tested in this study, number of herbicide treatments and N fertilization, were less influential. In general, our study corroborates the idea that some simple changes in farming activities, which are compatible with grape production, should be encouraged for improving the natural and cultural value of the landscape by

  20. Influence of subduction history on South American topography

    NASA Astrophysics Data System (ADS)

    Flament, Nicolas; Gurnis, Michael; Müller, 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

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

    PubMed

    Hackett, Troy A; Barkat, Tania Rinaldi; O'Brien, Barbara M J; Hensch, Takao K; Polley, Daniel B

    2011-02-23

    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 as well as in the ventral and medial divisions of the medial geniculate body (MGBv and MGBm, respectively). 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 with BF maps of neuronal spiking activity, the topographic order of subthreshold 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

  2. Topography of samples with variably aggregated metal particles

    NASA Astrophysics Data System (ADS)

    Schönauer, D.; Kreibig, U.

    1985-06-01

    A proper description of the optical (and other) properties of small particle samples containing clusters of interacting particles requires detailed information on the cluster topography. We present such an investigation performed on samples which were prepared from Au particle hydrosols, the clustering being controlled by addition of stabilizing agents. Numerical results are submitted for interdependencies between the number, the size and shape of aggregates and a Hausdorff dimension of 1.7 ± 0.2 is determined. Proper quantities are given, to detect even very low amounts of aggregation. There are indications that such samples may be modeled by introducing a few prototypic aggregates.

  3. Ocean topography experiment (TOPEX/Poseidon): Emergency support

    NASA Technical Reports Server (NTRS)

    Stiver, R. A.; Yamarone, C. A.

    1991-01-01

    The DSN (Deep Space Network) mission support requirements for the Ocean Topography Experiment (TOPEX/Poseidon) and the Global Positioning System (GPS) demonstration are summarized. The TOPEX mission consists of a single spacecraft which will be placed in a high earth circular orbit, with an altitude of 1334 km and a 63-deg inclination. The TOPEX mission objectives are outlined and the DSN support requirements are defined through the presentation of tables and narratives describing the spacecraft flight profile; DSN support coverage; frequency assignments; and tracking support responsibility.

  4. T-ray topography by time-domain polarimetry.

    PubMed

    Yasumatsu, Naoya; Watanabe, Shinichi

    2012-07-01

    We demonstrate a method for substantially improving the axial resolution of terahertz time-of-flight measurements by analyzing the time-dependent polarization direction of an elliptically polarized single-cycle terahertz electromagnetic (T-ray) pulse. We show that, at its most sensitive, the technique has an axial resolution of ∼λ/1000 (<1 μm) with a subsecond measurement time, and very clear T-ray topographic images are obtained. Such a very high axial resolution of the T-ray topography opens the way for novel industrial and biomedical applications such as fine metalworking and corneal inspection in a safe manner. PMID:22743502

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

    NASA Astrophysics Data System (ADS)

    Colwell, J. E.; Jakosky, B. M.; Sandor, B. J.; Stern, S. A.

    1990-05-01

    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.

  6. 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.

  7. 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

  8. 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

  9. 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

  10. 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

  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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. 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

  1. The Effect of Backside Particles on Substrate Topography

    NASA Astrophysics Data System (ADS)

    Bearda, Twan; Mertens, Paul W.; Holsteyns, Frank; De Bisschop, Peter; Compen, René; van Meer, Aschwin; Heyns, Marc M.

    2005-10-01

    The presence of a particle on the backside of a wafer is commonly acknowledged to produce a deflection of the wafer when it is held on a flat surface by means of a pressure difference. We simulated this wafer topography, taking into account both elastic and plastic deformations. The simulations are backed up by experimental evidence. The results show that height variations of 100 nm can extend over several mm. At the same time, indentation and plastic deformation reduce the surface height variations to values that are orders of magnitude below those predicted in the ITRS roadmap.

  2. Gravity Field, Topography, and Interior Structure of Amalthea

    NASA Astrophysics Data System (ADS)

    Anderson, J. D.; Anabtawi, A.; Jacobson, R. A.; Johnson, T. V.; Lau, E. L.; Moore, W. B.; Schubert, G.; Taylor, A. H.; Thomas, P. C.; Weinwurm, G.

    2002-12-01

    A close Galileo flyby of Jupiter's inner moon Amalthea (JV) occurred on 5 November 2002. The final aimpoint was selected by the Galileo Radio Science Team on 5 July 2002. The closest approach distance for the selected aimpoint was 221 km from the center of mass, the latitude was - 45.23 Deg and the west longitude was 266.41 Deg (IAU/IAG/COSPAR cartographic coordinate system). In order to achieve an acceptable impact probability (0.15%), and yet fly close to Amalthea, the trajectory was selected from a class of trajectories running parallel to Amalthea's long axis. The Deep Space Network (DSN) had the capability to generate continuous coherent radio Doppler data during the flyby. Such data can be inverted to obtain information on Amalthea's gravity field. Amalthea is irregular and neither a triaxial ellipsoid nor an equilibrium body. It has a volume of about 2.4 x 106 km3, and its best-fit ellipsoid has dimensions 131x73x67 km. Its mass can be determined from the 2002 flyby, and in combination with the volume, a density can be obtained accurate to about 5%, where the error is dominated by the volume uncertainty. Similarly, gravity coefficients (Cnm Snm) can be detected up to fourth degree and order, and the second degree field (quadrupole) can be measured. Topography data are available from Voyager imaging and from images taken with Galileo's solid state imaging system at various times between February and June 1997. By combining the gravity and topography data, new information can be obtained on Amalthea's interior. For example if the gravity coefficients agree with those calculated from the topography, assuming constant density, we can conclude that Amalthea is homogeneous. On the other hand, if the gravity coefficients are smaller than predicted from topography, we can conclude that there is a concentration of mass toward Amalthea's center. We are presenting preliminary pre-publication results at the Fall meeting. This work was sponsored by the Galileo Project

  3. Generalized Mathematical Model Predicting the Mechanical Processing Topography

    NASA Astrophysics Data System (ADS)

    Leonov, S. L.; Markov, A. M.; Belov, A. B.; Sczygol, N.

    2016-04-01

    We propose a unified approach for the construction of mathematical models for the formation of surface topography and calculation of its roughness parameters for different methods of machining processes. The approach is based on a process of geometric copy tool in the material which superimposes plastico-elastic deformation, oscillatory occurrences in processing and random components of the profile. The unified approach makes it possible to reduce the time forcreation of simulated stochastic model for a specific type of processing and guarantee the accuracy of geometric parameters calculation of the surface. We make an application example of generalized model for calculation of roughness density distribution Ra in external sharpening.

  4. 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

  5. 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 θ and θ(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

  6. Growth and surface topography of WSe2 single crystal

    NASA Astrophysics Data System (ADS)

    Dixit, Vijay; Vyas, Chirag; Pataniya, Pratik; Jani, Mihir; Pathak, Vishal; Patel, Abhishek; Pathak, V. M.; Patel, K. D.; Solanki, G. K.

    2016-05-01

    Tungsten Di-Selenide belongs to the family of TMDCs showing their potential applications in the fields of Optoelectronics and PEC solar cells. Here in the present investigation single crystals of WSe2 were grown by Direct Vapour Transport Technique in a dual zone furnace having temperature difference of 50 K between the two zones. These single crystals were characterized by EDAX which confirms the stiochiometry of the grown crystals. Surface topography of the crystal was studied by optical micrograph showing the left handed spirals on the surface of WSe2 crystals. Single crystalline nature of the crystals was confirmed by SAED.

  7. 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.

  8. 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 points—topographic relief—can 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.

  9. Age-related changes in skin topography and microcirculation.

    PubMed

    Li, Li; Mac-Mary, Sophie; Marsaut, David; Sainthillier, Jean Marie; Nouveau, Stéphanie; Gharbi, Tijani; de Lacharriere, Olivier; Humbert, Philippe

    2006-03-01

    Skin topography and microvasculature undergo characteristic changes with age. Although several non-invasive bioengineering methods are currently available to measure them quantitatively, few publications have referred to their relationship with age in different anatomical sites. This study was carried out to observe the age-related changes of the skin topography and skin microcirculation. The microrelief was assessed with special processing software from scanning by interference fringe profilometry of silicone replicas performed on two sites (volar forearm and back of hand) on 50 female volunteers (aged 20-74 years who consisted of ten probands in each decade). The superficial vascular network of both sites was assessed by videocapillaroscopy, and the subpapillary vascular plexus was studied with laser Doppler flowmetry. Skin color, which is affected by blood flow, was observed by colorimeter. The skin roughness and the mean height between peak and valley increased with age. There were statistically significant differences between the evaluated sites. This study also shows that the capillary loops in the dermal papillae decrease but the subpapillary plexus increase with age. The interference fringe profilometry associated with videocapillaroscopy may be useful and accurate to measure the efficacy of medical or cosmetic products to delay skin aging.

  10. 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.

  11. 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.

  12. Effects of shifter edge topography on through focus performance

    NASA Astrophysics Data System (ADS)

    Hotta, Shoji; Pistor, Thomas V.; Adam, Konstantinos; Neureuther, Andrew R.

    2001-01-01

    We have investigated the effects of the topography of the phase-shifting mask on the aerial image characteristics in DUV lithography. The calculation of near fields is carried out through simulation of the mask with TEMPEST and linking the resultant near fields to EM-Aerial for imaging. It is shown that the Fourier spectrum for an alternating phase-shifting mask can be decomposed into Fourier spectra for single openings. The amplitude and phase of the diffraction orders for the single opening are utilized for the systematic analysis of the shifter edge topography. The analysis framework developed in this paper clearly identifies the effects of the wall of the phase shifter, the residual transmittance through the chromium area, and the cross-talk between adjacent features. This analysis framework also allows these effects be merged in design. The near field profile in the vicinity of the shifter wall is also investigated for different feature sizes, and the optimum design for different feature sizes is discussed. The effect of the wall angle profile is shown to be acceptable.

  13. 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 2.5 s) and amplitude (with a factor of more than 4) across the seismic array. Such variations indicate that Earth's ICB is irregular, with a combination of at least two scales of topography: a height variation of 14 km changing within a lateral distance of no more than 6 km, and a height variation of 4-8 km with a lateral length scale of 2-4 km. The characteristics of the ICB topography indicate that small-scale variations of temperature and/or core composition exist near the ICB, and/or the ICB topographic surface is being deformed by small-scale forces out of its thermocompositional equilibrium position and is metastable.

  14. Genomic expression of mesenchymal stem cells to altered nanoscale topographies.

    PubMed

    Dalby, Matthew J; Andar, Abhay; Nag, Abhijit; Affrossman, Stanley; Tare, Rahul; McFarlane, Sara; Oreffo, Richard O C

    2008-09-01

    The understanding of cellular response to the shape of their environment would be of benefit in the development of artificial extracellular environments for potential use in the production of biomimetic surfaces. Specifically, the understanding of how cues from the extracellular environment can be used to understand stem cell differentiation would be of special interest in regenerative medicine. In this paper, the genetic profile of mesenchymal stem cells cultured on two osteogenic nanoscale topographies (pitted surface versus raised islands) are compared with cells treated with dexamethasone, a corticosteroid routinely used to stimulate bone formation in culture from mesenchymal stem cells, using 19k gene microarrays as well as 101 gene arrays specific for osteoblast and endothelial biology. The current studies show that by altering the shape of the matrix a cell response (genomic profile) similar to that achieved with chemical stimulation can be elicited. Here, we show that bone formation can be achieved with efficiency similar to that of dexamethasone with the added benefit that endothelial cell development is not inhibited. We further show that the mechanism of action of the topographies and dexamethasone differs. This could have an implication for tissue engineering in which a simultaneous, targeted, development of a tissue, such as bone, without the suppression of angiogenesis to supply nutrients to the new tissue is required. The results further demonstrate that perhaps the shape of the extracellular matrix is critical to tissue development. PMID:18270147

  15. 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.

  16. 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.

  17. Topography of Striate-Extrastriate Connections in Neonatally Enucleated Rats

    PubMed Central

    Laing, Robyn J.; Lasiene, Jurate; Olavarria, Jaime F.

    2013-01-01

    It is known that retinal input is necessary for the normal development of striate cortex and its corticocortical connections, but there is little information on the role that retinal input plays in the development of retinotopically organized connections between V1 and surrounding visual areas. In nearly all lateral extrastriate areas, the anatomical and physiological representation of the nasotemporal axis of the visual field mirrors the representation of this axis in V1. To determine whether the mediolateral topography of striate-extrastriate projections is preserved in neonatally enucleated rats, we analyzed the patterns of projections resulting from tracer injections placed at different sites along the mediolateral axis of V1. We found that the correlation between the distance from injection sites to the lateral border of V1 and the distance of the labeling patterns in area 18a was strong in controls and much weaker in enucleates. Data from pairs of injections in the same animal revealed that the separation of area 18a projection fields for a given separation of injection sites was more variable in enucleated than in control rats. Our analysis of single and double tracer injections suggests that neonatal bilateral enucleation weakens, but not completely abolishes, the mediolateral topography in area 18a. PMID:24199194

  18. 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.

  19. 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.

  20. The updated geodetic mean dynamic topography model - DTU15MDT.

    NASA Astrophysics Data System (ADS)

    Knudsen, Per; Andersen, Ole; Maximenko, Nikolai

    2016-04-01

    An update to the global mean dynamic topography model DTU13MDT is presented. For DTU15MDT the newer gravity model EIGEN-6C4 has been combined with the DTU15MSS mean sea surface model to construct this global mean dynamic topography model. The EIGEN-6C4 is derived using the full series of GOCE data and provides a better resolution. The better resolution fixes a few problems related to geoid signals in the former model DTU13MDT. Slicing in the GOCO05S gravity model up to harmonic degree 150 has solved some issues related to striations. Compared to the DTU13MSS, the DTU15MSS has been derived by including re-tracked CRYOSAT-2 altimetry also, hence, increasing its resolution. Also, some issues in the Polar regions have been solved. Finally, the filtering was re-evaluated by adjusting the quasi-gaussian filter width to optimize the fit to drifter velocities. Subsequently, geostrophic surface currents were derived from the DTU15MDT. The results show that geostrophic surface currents associated with the mean circulation have been further improved and that currents having speeds down to below 4 cm/s have been recovered.

  1. Influence of atmospheric structure and topography on infrasonic wave propagation

    NASA Astrophysics Data System (ADS)

    Lacanna, G.; Ichihara, M.; Iwakuni, M.; Takeo, M.; Iguchi, M.; Ripepe, M.

    2014-04-01

    The effects of topography and atmospheric structures on infrasonic wave propagation from a volcanic source were investigated using observations and numerical modeling. This paper presents the first long-term observational data set showing spatiotemporal variations in patterns of infrasound propagation at distances of up to 60 km from a persistently active infrasound source (Sakurajima Volcano, Japan). The data show that the amplitudes of infrasonic waves received at distant stations relative to those received at a reference station close to the source can vary up to an order of magnitude over short time intervals and short distances and that they do not follow the theoretical geometric decay expected for homogeneous media. Moreover, waveforms also change significantly in both time and space. Numerical simulations were performed using a two-dimensional finite difference time domain (2-D FDTD) method. Effects of atmospheric structure and topography are included in a vertical section parallel to the wave propagation direction. The simulation successfully reproduced the variations of amplitudes and waveforms. Results are interpreted in terms of wave refraction due to sound and wind speed gradients and wave diffraction at topographic barriers. Our numerical results indicate that both atmospheric and topographic propagation effects are nonnegligible. To evaluate the propagation effects and determine source processes in spatially and temporally varying infrasound data, atmospheric data with a time resolution higher than is currently available are required. If the data are available, the present results suggest that the propagation effects could be evaluated using 2-D FDTD modeling at realistic calculation times.

  2. A Martian general circulation experiment with large topography

    NASA Astrophysics Data System (ADS)

    Pollack, J. B.; Leovy, C. B.; Greiman, P. W.; Mintz, Y.

    1981-01-01

    A three-layer general circulation model of the Martian atmosphere is described, and the assumptions governing the model are discussed. The simulated, zonally averaged circulation is found to have only limited sensitivity to differences between this model and an earlier general circulation model; this circulation compares reasonably well with observations. It is also found that the meridional mass flow produced by the seasonal condensation of CO2 in the winter polar region has a major influence on the circulation; owing to the weak influence of atmospheric heat transport, however, the mass flow is governed almost entirely by radiation. Quasi-barotropic stationary waves, which are forced kinematically by the topography and which resemble topographically forced terrestrial planetary waves, are generated by the model in the winter hemisphere region of strong eastward flow, while baroclinic stationary waves are thermally forced by topography in the tropics and summer subtropics. It is also concluded that transient baroclinically unstable waves, of somewhat lower dominant wavenumber than those found on the earth, are generated in winter midlatitudes; their amplitudes, wavenumbers, and phase speeds closely agree with what has been deduced from the Viking lander observations.

  3. Storm-generated variations in nearshore beach topography

    USGS Publications Warehouse

    Lins, H.F.

    1984-01-01

    A series of nearshore beach profile measurements from the Outer Banks of North Carolina spanning a four-month period have been examined for temporal variations in nearshore topography. Principal component analysis of the profile data indicates that most of the variation in nearshore topography occurs in four principal modes, two quasiseasonal and two subseasonal. The first principal component, or eigenvector, corresponds to a bar-berm function. The second, to a terrace function. Combined, the first two vectors explain 76.3% of the total variance. The third and fourth components, representing subseasonal modes, are a ridge and runnel and a storm bar function, respectively. Both occur in direct response to storm wave activity. Although the bar-berm and terrace modes of profile variation have been previously identified using principal component analysis techniques, the subsequent modes have not. The ridge and runnel function accounts for 10.6% of total profile variability and the storm bar function accounts for 5.0%. ?? 1985.

  4. Transient coating of substrates with variable topography by viscous films

    NASA Astrophysics Data System (ADS)

    Lampropoulos, Nikos; Dimakopoulos, Yiannis; Tsamopoulos, John

    2015-11-01

    We study the transient coating of substrates exhibiting orthogonal trenches. We use the VoF method via OpenFOAM to solve the transient NS eqs on an unstructured grid, which dynamically undergoes local refinement around the interfaces. An Euler implicit method is used with adjustable time-step. The computational cost is reduced by parallel execution via MPI. Completely different wetting patterns result depending on the 3 dimensions of the topography, the capillary and Reynolds numbers and the dynamic contact angle. On one hand, continuous coating can be achieved in which the thin film of fluid wets the entire trench, while a steady flow is established upstream and downstream the topography. This is the desirable pattern in coating microelectronic devices for their protection and planarization. The other extreme possibility is that the film completely bypasses the trench, entrapping air inside it. This pattern reduces the drag coefficient on the film and, therefore, it is desirable in super-hydrophobic surfaces for microfluidic applications. Between these two extremes, a large variety of patterns exists in which the film partially wets the trench forming an air inclusion all along its bottom surface or its upstream or downstream inner corners or the film may breakup periodically. We produce comprehensive maps of film configurations covering a wide range of parameter values. GSRT of Greece via the program ``Excellence,'' Grant 1918.

  5. 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.

  6. Eyelid response topography in differential interstimulus interval conditioning.

    PubMed

    Kadlac, J A; Grant, D A

    1977-05-01

    The problem of conditioned eyelid discrimination was investigated with a differential interstimulus interval (ISI) conditioning procedure. In two groups, conditioned stimulus (CS) lights presented in the left or right visual fields signaled ISIs of 800 or 1,200 msec before delivery of an airpuff unconditioned stimulus. Two additional groups received one or the other ISI with both CSs. Somewhat unexpectedly, none of the response-frequency or topography measures showed evidence of conditioned discrimination in the differential ISI groups. Instead, the latencies and puff-attenuating topographies of responses were much more appropriate to the ISI given on the preceding trial, n--1, than to the ISI cued on trial n. Neither the absence of conditioned discrimination nor the presence of ISI sequential effects was related to subjects' reported awareness of the CS-ISI contingencies, suggesting that the overriding process was a relatively "automatic" shaping and reshaping of responses in accord with recent ISI experience. These results are discussed in terms of the complex stimulus- and response-processing requirements of the task. Across all four groups there was some evidence of a relative excitatory response bias to CSs presented in the right visual field, and it was found that voluntary-form responders (but not conditioned-form responders) initially gave more alpha responses to the right-field CS than to the left-field CS. These results were examined for possible hemispheric processing implications. PMID:870612

  7. First approximation of a stereochemical rationale for the genetic code based on the topography and physicochemical properties of "cavities" constructed from models of DNA.

    PubMed Central

    Hendry, L B; Bransome, E D; Hutson, M S; Campbell, L K

    1981-01-01

    To examine the question of whether or not the genetic code has a stereochemical basis, we used artificial constructs of the topography and physicochemical features of unique "cavities" formed by removal of the second codon base in B-DNA. The effects of base changes on the stereochemistry of the cavities are consistent with the pattern of the genetic code. Fits into the cavities of the side chains of the 20 L amino acids involved in protein synthesis can be demonstrated by using conventional physicochemical principles of hydrogen bonding and steric constraints. The specificity of the fits is remarkably consistent with the genetic code. Images PMID:6950386

  8. On the ratio of dynamic topography and gravity anomalies in a dynamic Earth

    NASA Astrophysics Data System (ADS)

    Colli, L.; Ghelichkhan, S.; Bunge, H.-P.

    2016-03-01

    Growing evidence from a variety of geologic indicators points to significant topography maintained convectively by viscous stresses in the mantle. However, while gravity is sensitive to dynamically supported topography, there are only small free-air gravity anomalies (<30 mGal) associated with Earth's long-wavelength topography. This has been used to suggest that surface heights computed assuming a complete isostatic equilibrium provide a good approximation to observed topography. Here we show that the apparent paradox is resolved by the well-established formalism of global, self-gravitating, viscously stratified Earth models. The models predict a complex relation between dynamic topography, mass, and gravity anomalies that is not summarized by a constant admittance—i.e., ratio of gravity anomalies to surface deflections—as one would infer from analytic flow solutions formulated in a half-space. Our results suggest that sizable dynamic topography may exist without a corresponding gravity signal.

  9. Internal structure of Io and the global distribution of its topography

    NASA Astrophysics Data System (ADS)

    Ross, M. N.; Schubert, G.; Spohn, T.; Gaskell, R. W.

    1990-06-01

    A global topography is presently calculated for two multilayer Io models in which dissipation occurs in a viscous asthenosphere and a solid mantle: (1) a 'thermal swell' model, in which topography and heat flow are positively correlated, and (2) a 'differentiated lithosphere' model, in which topography and heat flow are negatively correlated. Both the polar topography and the hypsometric distribution of elevations in the differentiated lithosphere model are better matched with observations than the thermal swell model. The shift of the equatorial basin-swell pattern indicates a recent zonal rotation of about 25 deg for Io's lithosphere.

  10. Fractal mapping of digitized images - Application to the topography of Arizona and comparisons with synthetic images

    NASA Technical Reports Server (NTRS)

    Huang, J.; Turcotte, D. L.

    1989-01-01

    The concept of fractal mapping is introduced and applied to digitized topography of Arizona. It is shown that the fractal statistics satisfy the topography of the state to a good approximation. The fractal dimensions and roughness amplitudes from subregions are used to construct maps of these quantities. It is found that the fractal dimension of actual two-dimensional topography is not affected by the adding unity to the fractal dimension of one-dimensional topographic tracks. In addition, consideration is given to the production of fractal maps from synthetically derived topography.

  11. 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

  12. 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

  13. 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

  14. Longevity and rheology of cratons: key constraints from surface topography

    NASA Astrophysics Data System (ADS)

    Francois, T.; Burov, E. B.; Meyer, B.; Agard, P.

    2011-12-01

    Archean cratons are stable remnants of Earth's early continental lithosphere. Their structure, composition and survival over geological time spans make them ones of the most unique and enigmatic features of the Earth's surface. It has become evident from both geophysical and petrological studies that cratons exhibit deep lithospheric roots, which remained stable ever since their formation in the early Archean. The question of how some of the cratons survived destruction over timescales of billions of years remains a subject of vigorous debate. In order to understand what controls the long-term stability of the cratons, we investigated the impact of the thermo-rheological structure of the lithosphere on the evolution of both surface topography and cratonic roots using fully coupled thermo-mechanical numerical models (600*3000 km, free upper surface topography, layered lithospheric structure). Our model has a particular focus on the Canadian Shield, where considerable structural and thermal data are available from both geological and geophysical studies. In particular, we compare the implications of the "Cratonic" "Jelly-Sandwich" rheology (JS; strong dry olivine mantle, strong crust, cold geotherm with Moho temperature of 400°C, thermal lithosphere thickness of 250 km) with those of the "Crème Brûlée" rheology (CB; strong crust, weak wet olivine mantle, Moho temperature of 600°C, thermal lithosphere thickness of 150 km) (Figure 1). Our experiments show that, in the case of a laterally homogeneous lithosphere and in the absence of tectonic shortening or extension (blocked borders), both JS and CB rheologies may account for the stability of the shield and its surface topography. In this case continental lithosphere remains stable over large time spans, even for the weakest wet olivine mantle (but for "cold" thermal gradients). Nevertheless, for a laterally heterogeneous crust, as is the case for the Canadian Shield and most cratons, dry olivine mantle JS rheology

  15. 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

  16. 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

  17. Forecasting hurricane impact on coastal topography: Hurricane Ike

    USGS Publications Warehouse

    Plant, Nathaniel G.; Stockdon, Hilary F.; Sallenger,, Asbury H.; 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.

  18. The Coastal Observation and Simulation with Topography (COAST) Experiment.

    NASA Astrophysics Data System (ADS)

    Bond, Nicholas A.; Mass, Clifford F.; Smull, Bradley F.; Houze, Robert A.; Yang, Ming-Jen; Colle, Brian A.; Braun, Scott A.; Shapiro, M. A.; Colman, Bradley R.; Neiman, Paul J.; Overland, James E.; Neff, William D.; Doyle, James D.

    1997-09-01

    The Coastal Observation and Simulation with Topography (COAST) program has examined the interaction of both steady-state and transient cool-season synoptic features, such as fronts and cyclones, with the coastal terrain of western North America. Its objectives include better understanding and forecasting of landfalling weather systems and, in particular, the modification and creation of mesoscale structures by coastal orography. In addition, COAST has placed considerable emphasis on the evaluation of mesoscale models in coastal terrain. These goals have been addressed through case studies of storm and frontal landfall along the Pacific Northwest coast using special field observations from a National Oceanic and Atmospheric Administration WP-3D research aircraft and simulations from high-resolution numerical models. The field work was conducted during December 1993 and December 1995. Active weather conditions encompassing a variety of synoptic situations were sampled. This article presents an overview of the program as well as highlights from a sample of completed and ongoing case studies.

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

    USGS Publications Warehouse

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

    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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Topography of the Martian tropical regions with ISM

    NASA Astrophysics Data System (ADS)

    Bibring, J.-P.; Erard, S.; Gondet, B.; Langevin, Y.; Soufflot, A.; Combes, M.; Cara, C.; Drossart, P.; Encrenaz, T.; Lellouch, E.; Rosenqvist, J.; Moroz, V. I.; Dyachkov, A. V.; Grygoriev, A. V.; Havinson, N. G.; Khatuntsev, I. V.; Kiselev, A. V.; Ksanfomality, L. V.; Nikolsky, Yu. V.; Masson, P.; Forni, O.; Sotin, C.

    1991-02-01

    The measurement of the CO2 column density on Mars, from the 2-micron band, in the Phobos/ISM spectra allows the determination of the altitude of the surface of Mars, with a horizontal spatial resolution of 20 km. The uncertainties involved in this method are described and compared with previous measurements of the Martian topography. Several topographic maps have been calculated, in the region of the high Martian volcanoes and Valles Marineris. Comparison with topographic maps derived from Mariner 9 and Viking measurements shows a good agreement. An average accuracy of about 400 m is obtained, which constitutes a significant improvement, compared with previous altimetry errors, of the order of 1 km. The method has a uniform accuracy over a full observation sequence (about 3000 km wide), and is complementary to the Viking photogrammetric measurements, more accurate on a 100 km scale.

  5. Self-report distortions of puffing topography in daily smokers.

    PubMed

    Pulcu, Erdem

    2016-08-01

    Under-reporting tobacco consumption is common, although there is lack of evidence whether under-reporting is associated with health risk perception. In this study, smoking topography from 110 smokers was recorded over 24 hours, aiming to capture a representative average of smoking behaviour. Participants significantly under-reported the duration of secondary exposure, and there was a significant interaction between self-report distortion type and risk perception. Analysis showed that smokers under-reporting puff number declared perceiving significantly less susceptibility to acquiring airway diseases, which is correlating significantly with the level of under-reporting. The present findings may suggest that under-reporting smoking behaviour has psychological functions beyond achieving social desirability.

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

    PubMed

    Cartwright, Lisa

    2016-01-01

    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

    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.

  8. 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.

  9. Large-scale stationary and turbulent flow over topography

    NASA Technical Reports Server (NTRS)

    Vallis, G. K.; Roads, J. O.

    1984-01-01

    The contributions made to the formation of stationary features of flow over topography by linear and nonlinear dynamics were examined with an integrated quasi-geostrophic model with idealized topographic forcing. The simulation was run out to several months and generated time-averaged values which were compared with those obtained with linear theory. Linear predictions were converted to turbulent features through the addition of stationary, nonlinear thermodynamic and transient vorticity fluxes. The turbulence features matched atmospheric data on energy spectra, the direction and magnitude of energy transfers, and the spatial magnitudes involved. Transient flow transferred the majority of energy absorbed by the upscale flow and, by absorbing energy, reduced the energy of stationary flow while retaining resonance signatures. Instability was a pervasive feature of the topographically forced flow except at high wavenumbers. The results confirm that transient eddies are interactive with both asymmetric and zonal flow and cannot be adequately described by linear theory.

  10. Topography-guided custom ablation treatment for treatment of keratoconus.

    PubMed

    Shetty, Rohit; D'Souza, Sharon; Srivastava, Samaresh; Ashwini, R

    2013-08-01

    Keratoconus is a progressive ectatic disorder of the cornea which often presents with fluctuating refraction and high irregular astigmatism. Correcting the vision of these patients is often a challenge because glasses are unable to correct the irregular astigmatism and regular contact lenses may not fit them very well. Topography-guided custom ablation treatment (T-CAT) is a procedure of limited ablation of the cornea using excimer laser with the aim of regularizing the cornea, improving the quality of vision and possibly contact lens fit. The aim of the procedure is not to give a complete refractive correction. It has been tried with a lot of success by various groups of refractive surgeons around the world but a meticulous and methodical planning of the procedure is essential to ensure optimum results. In this paper, we attempt to elucidate the planning for a T-CAT procedure for various types of cones and asphericities. PMID:23925335

  11. 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 substrate’s 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.

  12. Topography estimation with interferometric synthetic aperture radar using fringe detection

    NASA Technical Reports Server (NTRS)

    Lin, Qian; Vesecky, John F.; Zebker, Howard A.

    1991-01-01

    Methods are presented for using Synthetic Aperture Radar (SAR) interferometry data to estimate surface topography. An expression is given to relate the elevation of a ground point to the phase difference of SAR images received from two spatially separated antennas. An iterative algorithm which solves for the position and elevation of each point in the image simultaneously is developed. One of the critical issues that determines the accuracy of the terrain mapping is the phase unwrapping. An approach to the problem by fringe line detection is proposed. The algorithms are tested with two Seasat SAR images of terrain near Yellowstone National Park. The resultant elevation map is compared with a USGS terrain elevation model. The error of the SAR elevation with respect to the digital terrain map is about 8.2 percent of the total terrain variation.

  13. TOPOGRAPHY, STRESSES, AND STABILITY AT YUCCA MOUNTAIN, NEVADA.

    USGS Publications Warehouse

    Wolfs, Henri; Savage, William Z.

    1985-01-01

    Plane-strain solutions are used to analyze the influence of topography on the state of stress at Yucca Mountain, Nye County, Nevada. The results are in good agreement with the measured stress components obtained in drill holes by the hydraulic-fracturing technique, particularly those measured directly beneath the crest of the ridge, and indicate that these stresses are gravitationally induced. A separate analysis takes advantage of the fact that a well-developed set of vertical faults and fractures, subparallel to the ridge trend, imparts a vertical transverse isotropy to the rock and that, as a consequence of gravitational loading, unequal horizontal stresses are induced in directions perpendicular and parallel to the anisotropy.

  14. 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

  15. Characterization of Wheel Surface Topography in cBN Grinding

    NASA Astrophysics Data System (ADS)

    Fujimoto, Masakazu; Ichida, Yoshio; Sato, Ryunosuke; Morimoto, Yoshitaka

    The wheel surface topography in the grinding process with vitrified cBN wheels has been investigated on the basis of 3-dimensional analysis using a multi-probe SEM, and the relationships between these results and the grinding characteristic parameters have been discussed. Moreover, the change of the wheel surface profile in the grinding process has been evaluated using fractal analysis. There are two regions: an initial wear region and a steady-state wear region, in the grinding process. In the initial wear region, a rapid decrease of grinding force and a rapid increase of wheel wear occur with increasing stock removal. In the steady-state wear region, the micro self-sharpening phenomenon owing to the micro fracture as well as the attritious wear of cutting edge occurs. The change in fractal dimension of the wheel surface is closely related to the change of grinding force dominated by the wear behavior of grain cutting edges.

  16. 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.

  17. Scaffolds for hand tissue engineering: the importance of surface topography.

    PubMed

    Kloczko, E; Nikkhah, D; Yildirimer, L

    2015-11-01

    Tissue engineering is believed to have great potential for the reconstruction of the hand after trauma, congenital absence and tumours. Due to the presence of multiple distinct tissue types, which together function in a precisely orchestrated fashion, the hand counts among the most complex structures to regenerate. As yet the achievements have been limited. More recently, the focus has shifted towards scaffolds, which provide a three-dimensional framework to mimic the natural extracellular environment for specific cell types. In particular their surface structures (or topographies) have become a key research focus to enhance tissue-specific cell attachment and growth into fully functioning units. This article reviews the current understanding in hand tissue engineering before focusing on the potential for scaffold topographical features on micro- and nanometre scales to achieve better functional regeneration of individual and composite tissues.

  18. 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.

  19. 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.

  20. 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.

  1. 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

  2. PRINCIPLES UNDERLYING SENSORY MAP TOPOGRAPHY IN PRIMARY VISUAL CORTEX

    PubMed Central

    Kremkow, Jens; Jin, Jianzhong; Wang, Yushi; Alonso, Jose M.

    2016-01-01

    The primary visual cortex contains a detailed map of the visual scene, which is represented according to multiple stimulus dimensions including spatial location, ocular dominance and orientation. The maps for spatial location and ocular dominance originate from the spatial arrangement of thalamic axons in cortex. However, the origin of the other maps remains unclear. Here we demonstrate that the cortical maps for orientation, direction and retinal disparity are all strongly related to the organization for spatial location of light (ON) and dark (OFF) stimuli, an organization that we show is OFF-dominated, OFF-centric and runs orthogonal to ocular dominance columns. Because this ON/OFF organization originates from the clustering of ON and OFF thalamic afferents in visual cortex, we conclude that all main features of cortical topography, including orientation, direction and retinal disparity, follow a common organizing principle that arranges thalamic axons with similar retinotopy and ON/OFF polarity in neighboring cortical regions. PMID:27120164

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Arctic Dynamic Topography and Surface Currents from Cryosat-2

    NASA Astrophysics Data System (ADS)

    Thomas, S. F.; Ridout, A.

    2015-12-01

    The Arctic Ocean is known to be a region of significance in global climate, and has been observed to undergo drastic changes in recent decades. As research continues to understand the Arctic and the interaction of atmosphere, ice & ocean, a key area of study is ocean circulation - the investigation of which has traditionally been hampered by the region's harsh and ice-covered nature. However with the advent of polar altimetry and the development of lead retracking, we may draw back the veil of sea ice and study the ocean beneath. We use UCL's well-developed sea ice retracking techniques to acquire sea surface height (SSH) measurements at leads across the Arctic. These data are used to produce a sea surface field, which is combined with the geoid to calculate dynamic topography and associated geostrophic currents. By adjusting the processing of SSH measurements we may examine surface currents on different time scales, from the multi-year mean state to annual and monthly variations. We demonstrate the major improvement in coverage and resolution offered by Cryosat-2, as well as comparison against in-situ data. We show the variations in currents visible on different time scales, and discuss the considerations of processing data on these time scales with reference to Cryosat's ground track/sampling pattern. We examine the potential effect of irregular distributions of leads, and the significance of any bias introduced by melt ponds in summer. We also show the improvements offered by using a combined (rather than satellite-only) geoid solution, and the caveats thereof. Finally, we look to methods of improving Arctic dynamic topography products in the future.

  8. Density constraints of lunar upper crust from gravity and topography

    NASA Astrophysics Data System (ADS)

    Huang, Q.; Wieczorek, M. A.; Ping, J.

    2011-12-01

    Remote sensing and in situ measurements have shown that there are large lateral and vertical variations in the composition of the lunar crust. These crustal density diversities can be investigated using newly obtained global gravity and topography data. We applied a localized spectral admittance technique to various crustal regions by windowing the free-air gravity and surface topography with the band-limited localization windows of Wieczorek and Simons (2005, 2007). These admittances were interpreted using a geophysical model that includes both surface and subsurface loads that are supported by an elastic lithosphere. By varying the crustal density, elastic thickness and loading ratio in certain ranges, the best fitting bulk densities for a number of homogeneous regions were constrained to vary laterally from 2590 kg m-3 to 3010 kg m-3, with a mean value of 2700 kg m-3. Assuming the composition of the upper crust is uniform, the porosity of the upper crust could be determined if the pore-free surface density is known. Based on the known compositions of lunar rocks and estimated mineralogical norms, we found that the pore-free densities of lunar rocks were highly correlated with FeO and TiO2 abundance. The rock density can vary from 2884 to 3038 kg m-3 in estimated regions by using the iron and titanium abundances from Lunar Prospector gamma-ray spectrometer. We calculated the porosity of each region and found a mean value of ~7.4±3.4%, with permissible values from 0 to 14%. Furthermore, we took into account the vertical variation of crust density, and developed a novel technique that the density profile of the crust could be inverted using higher resolution gravity models. Since all these analyses are challenging using the recent Kaguya gravity models, higher resolution gravity data expected from NASA's Gravity Recovery and Interior Laboratory (GRAIL) mission would place tight constrains on both the lateral and vertical density variations of the lunar crust.

  9. 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

  10. 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.

  11. Holographic topography using acousto-optically generated large synthetic wavelengths

    NASA Astrophysics Data System (ADS)

    Abeywickrema, U.; Beamer, D.; Banerjee, P.; Poon, T.-C.

    2016-03-01

    Digital holography uses phase imaging in a variety of techniques to produce a three-dimensional phase resolved image that includes accurate depth information about the object of interest. Multi-wavelength digital holography is an accurate method for measuring the topography of surfaces. Typically, the object phases are reconstructed for two wavelengths separately and the phase corresponding to the synthetic wavelength (obtained from the two wavelengths) is obtained by calculating the phase difference. Then the surface map can be obtained using proper phase-unwrapping techniques. Usually these synthetic wavelengths are on the order of microns which can be used to resolve depths on the order of microns. In this work, two extremely close wavelengths generated by an acousto-optic modulator (AOM) are used to perform two-wavelength digital holography. Since the difference between the two wavelengths is on the order of picometers, a large synthetic wavelength (on the order of centimeters) can be obtained which can be used to determine the topography of macroscopic surface features. Also since the synthetic wavelength is large, an accurate surface map can be obtained without using a phase-unwrapping technique. A 514 nm Argon-ion laser is used as the optical source, and used with an AOM to generate the zeroth-order and frequency-shifted first-order diffracted orders which are used as the two wavelengths. Both beams are aligned through the same spatial filter assembly. Holograms are captured sequentially using a typical Mach-Zehnder interferometric setup by blocking one beam at a time. Limitations of the large synthetic wavelength are also discussed.

  12. The subthalamic nucleus. Part I: development, cytology, topography and connections.

    PubMed

    Marani, Enrico; Heida, Tjitske; Lakke, Egbert A J F; Usunoff, Kamen G

    2008-01-01

    This monograph (Part I of two volumes) on the subthalamic nucleus (STN) accentuates the gap between experimental animal and human information concerning subthalamic development, cytology, topography and connections. The light and electron microscopical cytology focuses on the open nucleus concept and the neuronal types present in the STN. The cytochemistry encompasses enzymes, NO, glial fibrillary acidic protein (GFAP), calcium binding proteins, and receptors (dopamine, cannabinoid, opioid, glutamate, gamma-aminobutyric acid (GABA), serotonin, cholinergic, and calcium channels). The ontogeny of the subthalamic cell cord is also reviewed. The topography concerns the rat, cat, baboon and human STN. The descriptions of the connections are also given from a historical point of view. Recent tracer studies on the rat nigro-subthalamic connection revealed contralateral projections. Part II of the two volumes (volume 199) on the subthalamic nucleus (STN) starts with a systemic model of the basal ganglia to evaluate the position of the STN in the direct, indirect and hyperdirect pathways. A summary of in vitro studies is given, describing STN spontaneous activity as well as responses to depolarizing and hyperpolarizing inputs and high-frequency stimulation. STN bursting activity and the underlying ionic mechanisms are investigated. Deep brain stimulation used for symptomatic treatment of Parkinson's disease is discussed in terms of the elements that are influenced and its hypothesized mechanisms. This part of the monograph explores the pedunculopontine-subthalamic connections and summarizes attempts to mimic neurotransmitter actions of the pedunculopontine nucleus in cell cultures and high-frequency stimulation on cultured dissociated rat subthalamic neurons. STN cell models--single- and multi-compartment models and system-level models are discussed in relation to subthalamic function and dysfunction. Parts I and II are compared. PMID:18727483

  13. 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.

  14. Lunar South Pole Topography Derived from Clementine Imagery

    NASA Astrophysics Data System (ADS)

    Rosiek, M. R.; Kirk, R.; Howington-Kraus, A.

    1999-01-01

    During the Clementine Mission both oblique and vertical multispectral images were collected. The oblique and vertical images from a single spectral band collected during the same orbit form a stereo pair that can be used to derive the topography. These stereo pairs are being used to derive the topography of an area (90 deg S to 650S latitude) surrounding the lunar south pole. Work on the lunar north pole topography will start after completion of the south pole topography. This report provides an update on the initial results for the lunar south pole topography. In 1994, the Clementine spacecraft acquired digital images of the Moon at visible and near-infrared wavelengths. Onboard there were four camera systems and a laser altimeter. During the first pass, periapsis was at 30S and the highest resolution images were obtained in the southern hemisphere. Over the northern polar area, a series of oblique and vertical images were obtained with the ultraviolet-visible (UV-VIS) camera on each orbit. During the second pass, periapsis was at 30N and the image acquisition strategy was reversed. The UV-VIS camera image size was 384 x 288 pixels with five spectral bands and one broad band. The 750-nm-band stereo pairs are the primary image source for this study. The ground sample distances (GSD) for oblique images range from 300 to 400m. The GSD for the vertical images, acquired at the end of an orbit, are slightly larger and range from 325 to 450 m. Using the formula for stereo-height accuracy, an estimate of height accuracy is 180m. This formula is IFOVMAX)/(K*B/H with IFOVMAX defined as Maximum Instantaneous Field of View; B/H is the base-to-height ratio and K is an estimate of pixel measurement accuracy on the imagery. The Clementine laser altimeter (LIDAR) data were used previously to produce a global topographic model of the Moon . The model has a vertical accuracy of about 100 m and a spatial resolution of 2.5 deg. Altimetry data were collected between 79S and 810N

  15. 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 200°C 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 μm produced a significant difference (P<0.001) in roughness from 4.8 and 9.7 μm. 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 μm) compared to the as-sprayed and polished coating (5 μm). 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.

  16. Preliminary Results of an Examination of Electronic Cigarette User Puff Topography: The Effect of a Mouthpiece-Based Topography Measurement Device on Plasma Nicotine and Subjective Effects

    PubMed Central

    Spindle, Tory R.; Breland, Alison B.; Karaoghlanian, Nareg V.; Shihadeh, Alan L.

    2015-01-01

    Introduction: Electronic cigarettes (ECIGs) heat a nicotine-containing solution; the resulting aerosol is inhaled by the user. Nicotine delivery may be affected by users’ puffing behavior (puff topography), and little is known about the puff topography of ECIG users. Puff topography can be measured using mouthpiece-based computerized systems. However, the extent to which a mouthpiece influences nicotine delivery and subjective effects in ECIG users is unknown. Methods: Plasma nicotine concentration, heart rate, and subjective effects were measured in 13 experienced ECIG users who used their preferred ECIG and liquid (≥12mg/ml nicotine) during 2 sessions (with or without a mouthpiece). In both sessions, participants completed an ECIG use session in which they were instructed to take 10 puffs with 30-second inter-puff intervals. Puff topography was recorded in the mouthpiece condition. Results: Almost all measures of the effects of ECIG use were independent of topography measurement. Collapsed across session, mean plasma nicotine concentration increased by 16.8ng/ml, and mean heart rate increased by 8.5 bpm (ps < .05). Withdrawal symptoms decreased significantly after ECIG use. Participants reported that the mouthpiece affected awareness and made ECIG use more difficult. Relative to previously reported data for tobacco cigarette smokers using similar topography measurement equipment, ECIG-using participants took larger and longer puffs with lower flow rates. Conclusions: In experienced ECIG users, measuring ECIG topography did not influence ECIG-associated nicotine delivery or most measures of withdrawal suppression. Topography measurement systems will need to account for the low flow rates observed for ECIG users. PMID:25239957

  17. Topographies of Power: A Critical Historical Geography of Schooling in Tanzania

    ERIC Educational Resources Information Center

    Vavrus, Frances

    2016-01-01

    This article builds a case for critical historical geography in comparative education to examine how, over time, the social production of space contributes to educational disparity. It draws on Gupta and Ferguson's contrasting concepts of the "power of topography" and the "topography of power" and Lefebvre's tripartite theory…

  18. Can weak crust explain the correlation of geoid and topography on Venus?

    NASA Technical Reports Server (NTRS)

    Buck, W. Roger

    1993-01-01

    The effect on geoid and topography of low viscosity crust overlying a steady-state convecting mantle is estimated under the assumption that the shear between crust and mantle does not alter the mantle flow. The weak crustal layer can change the sign of the geoid to topography ratio (admittance). The positive long wavelength admittance for Venus is consistent with a weak crust overlying a mantle with a viscosity that increases strongly with depth. The accepted interpretation of the strong positive correlation of geoid and topography on Venus, is that the convecting mantle of Venus has a constant viscosity with depth. Topography results from vertical normal stresses caused by mantle convection and highlands occur where mantle upwells. For topography to be supported by normal stress, the time scale for crustal flow must be long compared to the time scale for changes in the pattern of mantle flow. Because the high surface temperature of Venus may cause the crust to have a low viscosity, this assumption may be false. Topography should then be dominated by shear coupling between the crust and mantle. In the absence of a crustal layer, convection in a constant viscosity layer gives rise to a geoid anomaly that correlates positively with surface topography. When the viscosity in the layer increases with depth by several orders of magnitude, the surface topography and geoid anomaly become anti-correlated.

  19. 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…

  20. Fine-scale topography in sensory systems: insights from Drosophila and vertebrates.

    PubMed

    Kaneko, Takuya; Ye, Bing

    2015-09-01

    To encode the positions of sensory stimuli, sensory circuits form topographic maps in the central nervous system through specific point-to-point connections between pre- and postsynaptic neurons. In vertebrate visual systems, the establishment of topographic maps involves the formation of a coarse topography followed by that of fine-scale topography that distinguishes the axon terminals of neighboring neurons. It is known that intrinsic differences in the form of broad gradients of guidance molecules instruct coarse topography while neuronal activity is required for fine-scale topography. On the other hand, studies in the Drosophila visual system have shown that intrinsic differences in cell adhesion among the axon terminals of neighboring neurons instruct the fine-scale topography. Recent studies on activity-dependent topography in the Drosophila somatosensory system have revealed a role of neuronal activity in creating molecular differences among sensory neurons for establishing fine-scale topography, implicating a conserved principle. Here we review the findings in both Drosophila and vertebrates and propose an integrated model for fine-scale topography.

  1. Bed topography and sand transport responses to a step change in discharge and water depth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ephemeral streams with sand and gravel beds may inherit bed topography caused by previous flow events, resulting in bed topography that is not in equilibrium with flow conditions, complicating the modeling of flow and sediment transport. Major flow events, resulting from rainfall with high intensity...

  2. Fine-scale topography in sensory systems: insights from Drosophila and vertebrates.

    PubMed

    Kaneko, Takuya; Ye, Bing

    2015-09-01

    To encode the positions of sensory stimuli, sensory circuits form topographic maps in the central nervous system through specific point-to-point connections between pre- and postsynaptic neurons. In vertebrate visual systems, the establishment of topographic maps involves the formation of a coarse topography followed by that of fine-scale topography that distinguishes the axon terminals of neighboring neurons. It is known that intrinsic differences in the form of broad gradients of guidance molecules instruct coarse topography while neuronal activity is required for fine-scale topography. On the other hand, studies in the Drosophila visual system have shown that intrinsic differences in cell adhesion among the axon terminals of neighboring neurons instruct the fine-scale topography. Recent studies on activity-dependent topography in the Drosophila somatosensory system have revealed a role of neuronal activity in creating molecular differences among sensory neurons for establishing fine-scale topography, implicating a conserved principle. Here we review the findings in both Drosophila and vertebrates and propose an integrated model for fine-scale topography. PMID:26091779

  3. Fine-scale topography in sensory systems: insights from Drosophila and vertebrates

    PubMed Central

    Kaneko, Takuya; Ye, Bing

    2015-01-01

    To encode the positions of sensory stimuli, sensory circuits form topographic maps in the central nervous system through specific point-to-point connections between pre- and post-synaptic neurons. In vertebrate visual systems, the establishment of topographic maps involves the formation of a coarse topography followed by that of fine-scale topography that distinguishes the axon terminals of neighboring neurons. It is known that intrinsic differences in the form of broad gradients of guidance molecules instruct coarse topography while neuronal activity is required for fine-scale topography. On the other hand, studies in the Drosophila visual system have shown that intrinsic differences in cell adhesion among the axon terminals of neighboring neurons instruct the fine-scale topography. Recent studies on activity-dependent topography in the Drosophila somatosensory system have revealed a role of neuronal activity in creating molecular differences among sensory neurons for establishing fine-scale topography, implicating a conserved principle. Here we review the findings in both Drosophila and vertebrates and propose an integrated model for fine-scale topography. PMID:26091779

  4. Ground topography effects on near-surface elastic full waveform inversion

    NASA Astrophysics Data System (ADS)

    Nuber, André; Manukyan, Edgar; Maurer, Hansruedi

    2016-07-01

    The effects of neglecting ground surface topography variations in elastic full waveform inversion are investigated using two classes of synthetic example. The models include various high-contrast velocity and density anomalies, as they are often observed in near-surface applications. The first type of example shows that failing to account for even small amplitude fluctuations in topography introduces velocity artefacts in the near-surface part of the tomogram as well as degrades significantly the spatial resolution of features at greater depths. The disturbances are particularly severe when the topographic fluctuations have wavelengths comparable to the minimum seismic wavelength. The second type of synthetic example considers long wavelength topography variations of various amplitudes. It is found that neglecting topography with an amplitude fluctuation greater than half the minimum seismic wavelength leads to appreciable inversion image artefacts. Therefore, the incorporation of surface topography, even if it appears minor, is essential for successful elastic full waveform inversion of land seismic data.

  5. Ground topography effects on near-surface elastic full waveform inversion

    NASA Astrophysics Data System (ADS)

    Nuber, André; Manukyan, Edgar; Maurer, Hansruedi

    2016-10-01

    The effects of neglecting ground surface topography variations in elastic full waveform inversion are investigated using two classes of synthetic example. The models include various high-contrast velocity and density anomalies, as they are often observed in near-surface applications. The first type of example shows that failing to account for even small amplitude fluctuations in topography introduces velocity artefacts in the near-surface part of the tomogram as well as degrades significantly the spatial resolution of features at greater depths. The disturbances are particularly severe when the topographic fluctuations have wavelengths comparable to the minimum seismic wavelength. The second type of synthetic example considers long wavelength topography variations of various amplitudes. It is found that neglecting topography with an amplitude fluctuation greater than half the minimum seismic wavelength leads to appreciable inversion image artefacts. Therefore, the incorporation of surface topography, even if it appears minor, is essential for successful elastic full waveform inversion of land seismic data.

  6. 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.

  7. Aspects of Radiation Budget, Subsurface Lateral Moisture Exchange, and Vegetation Function in Areas of Complex Topography.

    NASA Astrophysics Data System (ADS)

    Ivanov, V. Y.; Bras, R. L.; Istanbulluoglu, E.; Vivoni, E. R.

    2004-12-01

    There is evidence that topography strongly affects the state, function, and distribution of vegetation by controlling incoming solar radiation and lateral redistribution of soil moisture. However, numerical experiments studying the effects that a topography can have on vegetation have oversimplified the treatment of topography and/or the representation of vegetation. We investigate the control of topography on vegetation state and stress via detailed modeling of radiation and soil moisture budgets across the varied terrain of a watershed. A detailed vegetation-hydrology model parameterizes the processes of canopy radiative transfer and rainfall interception and couples the processes of infiltration and evapotranspiration to photosynthesis via moisture uptake through a root systems with varied profiles. The model is applied on a continuous basis to synthetic watersheds of topography dominated by either convex or concave hillslopes. The numerical analysis is carried out for several plant functional types and soils. Inferences from the spatially-distributed dynamics are used to examine topographic niches favorable to vegetation.

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

    NASA Astrophysics Data System (ADS)

    Michalski, J.; Pawlus, P.; Żelasko, 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.

  9. 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.

  10. Breaking Gravity Waves Over Large-Scale Topography

    NASA Astrophysics Data System (ADS)

    Doyle, J. D.; Shapiro, M. A.

    2002-12-01

    The importance of mountain waves is underscored by the numerous studies that document the impact on the atmospheric momentum balance, turbulence generation, and the creation of severe downslope winds. As stably stratified air is forced to rise over topography, large amplitude internal gravity waves may be generated that propagate vertically, amplify and breakdown in the upper troposphere and lower stratosphere. Many of the numerical studies reported on in the literature have used two- and three-dimensional models with simple, idealized initial states to examine gravity wave breaking. In spite of the extensive previous work, many questions remain regarding gravity wave breaking in the real atmosphere. Outstanding issues that are potentially important include: turbulent mixing and wave overturning processes, mountain wave drag, downstream effects, and the mesoscale predictability of wave breaking. The current limit in our knowledge of gravity wave breaking can be partially attributed to lack of observations. During the Fronts and Atlantic Storm-Track Experiment (FASTEX), a large amplitude gravity wave was observed in the lee of Greenland on 29 January 1997. Observations taken collected during FASTEX presented a unique opportunity to study topographically forced gravity wave breaking and to assess the ability of high-resolution numerical models to predict the structure and evolution of such phenomena. Measurements from the NOAA G-4 research aircraft and high-resolution numerical simulations are used to study the evolution and dynamics of the large-amplitude gravity wave event that took place during the FASTEX. Vertical cross section analysis of dropwindsonde data, with 50-km horizontal spacing, indicates the presence of a large amplitude breaking gravity wave that extends from above the 150-hPa level to 500 hPa. Flight-level data indicate a horizontal shear of over 10-3 s-1 across the breaking wave with 25 K potential temperature perturbations. This breaking wave may

  11. [Quantitative assessment of facial palsy by Moiré topography].

    PubMed

    Inokuchi, I

    1992-05-01

    It is essential to establish an objective and quantitative method for evaluating facial palsy and to measure the extent of paralysis in order to evaluate therapeutic efficacy, determine prognosis, select appropriate treatment and observe the process of recovery. This study utilized Moiré topography, which displays three-dimensional facial symmetry with high precision and is based on light interference theory, to determine the extent of facial palsy in 38 patients (20 men and 18 women) 5 months to 73 years of age. A stereoscopic lattice type Moiré camera (FM3013) was connected to a CCD camera and to the monitoring device for confirming Moiré stripes. Moiré photographs were taken with a thermal imager (FTI-200). The photos were visually and objectively evaluated on the basis of the Moiré pattern and were then input into a personal computer with a digitizer for data processing and analysis. To view the functions of facial nerve branches, five Moiré photographs were taken: at rest, wrinkling the forehead, closing the eyes lightly, blowing out the cheeks and grinning. Results indicated that the number of stripes and their polarization adequately reflected the function of individual facial nerve branches. Thus, a well-defined Moiré pattern could clarify the characteristics of the site and the degree of facial palsy and of recovery from paralysis. It is an analytical method that can be quickly applied and seems especially useful in infants and young children, in whom point-based assessment is difficult. It is possible to quantitatively evaluate facial palsy in terms of the Asymmetry Index (AI), which is 20-25% for severe paralysis, 12-19% for partial paralysis, and 5-10% for an essentially normal condition. However, the numerical value of the AI overlap in all three paralysis categories, indicating that quantitative assessment of paralysis would be difficult. Moiré topography is an excellent method of determining the extent of facial palsy, compensating for the

  12. The Interior of Enceladus from Gravity and Topography

    NASA Astrophysics Data System (ADS)

    Iess, L.

    2015-12-01

    The combination of gravity and topography has been the method of choice to obtain quantitative information on the interior of Enceladus, but its application was challenging because of the small mass of the moon and the short gravitational interaction time with the Cassini spacecraft. The main observable quantity used in the estimation of the gravity field was the spacecraft range rate, measured by the antennas of NASA's Deep Space Network to an accuracy of about 0.03 mm/s (at 60 s integration time). In spite of these challenges and thanks to the careful design of three gravity flybys, Cassini was able to catch the essential features of Enceladus's gravity field, in particular to estimate its quadrupole and detect the sought-for hemispherical asymmetry [1]. Crucial for the correct fit of the Doppler data was the inclusion in the dynamical model of the drag acceleration from the plume's neutral particles. Although the largest quadrupole coefficients indicate only a mild deviation from hydrostatic equilibrium (J2/C22=3.55±0.05), a reliable determination of the MOIF uses J3 to separate the hydrostatic and non-hydrostatic components of the quadrupole field. The application of this method results in a MOIF (0.336) compatible with a differentiated structure. (An admittance analysis leads to a similar value.) The magnitude and the sign of J3 indicate that the gravity anomaly associated to the striking topographic depression (-1 km) in the southern polar regions is largely compensated by denser material at depth. The obvious (but not the only) interpretation points to a liquid water mass, denser than the surrounding ice and sandwiched between the ice shell and the rocky core. The gravity field and the topography provide also rough estimate of the size of the water mass and the depth at which it is located. Starting from the consideration that the hydrostatic J2/C22 ratio for a fast rotator like Enceladus is about 3.25 and not 10/3, a recent work [2] offers some adjustments

  13. Dental topography indicates ecological contraction of lemur communities.

    PubMed

    Godfrey, Laurie R; Winchester, Julia M; King, Stephen J; Boyer, Doug M; Jernvall, Jukka

    2012-06-01

    Understanding the paleoecology of extinct subfossil lemurs requires reconstruction of dietary preferences. Tooth morphology is strongly correlated with diet in living primates and is appropriate for inferring dietary ecology. Recently, dental topographic analysis has shown great promise in reconstructing diet from molar tooth form. Compared with traditionally used shearing metrics, dental topography is better suited for the extraordinary diversity of tooth form among subfossil lemurs and has been shown to be less sensitive to phylogenetic sources of shape variation. Specifically, we computed orientation patch counts rotated (OPCR) and Dirichlet normal energy (DNE) of molar teeth belonging to 14 species of subfossil lemurs and compared these values to those of an extant lemur sample. The two metrics succeeded in separating species in a manner that provides insights into both food processing and diet. We used them to examine the changes in lemur community ecology in Southern and Southwestern Madagascar that accompanied the extinction of giant lemurs. We show that the poverty of Madagascar's frugivore community is a long-standing phenomenon and that extinction of large-bodied lemurs in the South and Southwest resulted not merely in a loss of guild elements but also, most likely, in changes in the ecology of extant lemurs.

  14. Surface topography effects in protein adsorption on nanostructured carbon allotropes.

    PubMed

    Raffaini, Giuseppina; Ganazzoli, Fabio

    2013-04-16

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

  15. Accuracy Assessment of Coastal Topography Derived from Uav Images

    NASA Astrophysics Data System (ADS)

    Long, N.; Millescamps, B.; Pouget, F.; Dumon, A.; Lachaussée, N.; Bertin, X.

    2016-06-01

    To monitor coastal environments, Unmanned Aerial Vehicle (UAV) is a low-cost and easy to use solution to enable data acquisition with high temporal frequency and spatial resolution. Compared to Light Detection And Ranging (LiDAR) or Terrestrial Laser Scanning (TLS), this solution produces Digital Surface Model (DSM) with a similar accuracy. To evaluate the DSM accuracy on a coastal environment, a campaign was carried out with a flying wing (eBee) combined with a digital camera. Using the Photoscan software and the photogrammetry process (Structure From Motion algorithm), a DSM and an orthomosaic were produced. Compared to GNSS surveys, the DSM accuracy is estimated. Two parameters are tested: the influence of the methodology (number and distribution of Ground Control Points, GCPs) and the influence of spatial image resolution (4.6 cm vs 2 cm). The results show that this solution is able to reproduce the topography of a coastal area with a high vertical accuracy (< 10 cm). The georeferencing of the DSM require a homogeneous distribution and a large number of GCPs. The accuracy is correlated with the number of GCPs (use 19 GCPs instead of 10 allows to reduce the difference of 4 cm); the required accuracy should be dependant of the research problematic. Last, in this particular environment, the presence of very small water surfaces on the sand bank does not allow to improve the accuracy when the spatial resolution of images is decreased.

  16. The role of bedrock topography on subsurface storm flow

    USGS Publications Warehouse

    Freer, J.; McDonnell, Jeffery J.; Beven, K.J.; Peters, N.E.; Burns, Douglas A.; Hooper, R.P.; Aulenbach, B.; Kendall, C.

    2002-01-01

    We conducted a detailed study of subsurface flow and water table response coupled with digital terrain analysis (DTA) of surface and subsurface features at the hillslope scale in Panola Mountain Research Watershed (PMRW), Georgia. Subsurface storm flow contributions of macropore and matrix flow in different sections along an artificial trench face were highly variable in terms of timing, peak flow, recession characteristics, and total flow volume. The trench flow characteristics showed linkages with the spatial tensiometer response defining water table development upslope. DTA of the ground surface did not capture the observed spatial patterns of trench flow or tensiometric response. However, bedrock surface topographic indices significantly improved the estimation of spatial variation of flow at the trench. Point-scale tensiometric data were also more highly correlated with the bedrock surface-based indices. These relationships were further assessed for temporal changes throughout a rainstorm. Linkages between the bedrock indices and the trench flow and spatial water table responses improved during the wetter periods of the rainstorm, when the hillslope became more hydrologically connected. Our results clearly demonstrate that in developing a conceptual framework for understanding the mechanisms of runoff generation, local bedrock topography may be highly significant at the hillslope scale in some catchments where the bedrock surface acts as a relatively impermeable boundary.

  17. 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

  18. 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.

  19. 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.

  20. Substrate Topography Determines Neuronal Polarization and Growth In Vitro

    PubMed Central

    Micholt, Liesbeth; Gärtner, Annette; Prodanov, Dimiter; Braeken, Dries; Dotti, Carlos G.; Bartic, Carmen

    2013-01-01

    The establishment of neuronal connectivity depends on the correct initial polarization of the young neurons. In vivo, developing neurons sense a multitude of inputs and a great number of molecules are described that affect their outgrowth. In vitro, many studies have shown the possibility to influence neuronal morphology and growth by biophysical, i.e. topographic, signaling. In this work we have taken this approach one step further and investigated the impact of substrate topography in the very early differentiation stages of developing neurons, i.e. when the cell is still at the round stage and when the first neurite is forming. For this purpose we fabricated micron sized pillar structures with highly reproducible feature sizes, and analyzed neurons on the interface of flat and topographic surfaces. We found that topographic signaling was able to attract the polarization markers of mouse embryonic neurons -N-cadherin, Golgi-centrosome complex and the first bud were oriented towards topographic stimuli. Consecutively, the axon was also preferentially extending along the pillars. These events seemed to occur regardless of pillar dimensions in the range we examined. However, we found differences in neurite length that depended on pillar dimensions. This study is one of the first to describe in detail the very early response of hippocampal neurons to topographic stimuli. PMID:23785482

  1. SAR Image Coregistration Based on Topography and Deformation

    NASA Astrophysics Data System (ADS)

    Yun, S.; Kim, S.; Rosen, P.

    2008-12-01

    L-band repeat-pass InSAR has been getting scientists' attention for its penetration depth through dense vegetation, revealing the ground deformation under the canopy of forest. This makes it possible to achieve a good coverage of volcanic activities in tropical areas such as Hawaii, Galapagos, and Indonesia. Another advantage of L-band InSAR is its tolerance to a large baseline. The critical baseline scales with the wavelength, and practically a baseline of over 1 km often produces interferograms. However, the large baseline causes parallax in the presence of topography, which appears as pixel shift between master and slave images that sometimes leads to a severe decorrelation. Using ALOS PALSAR data of Java Island, Indonesia, and intermediate files produced by ROI_PAC, we correct this parallax before forming an interferogram to improve the interferometric coherence. We also test an automatic implementation of the 'rubber sheeting" coregistration (e.g. Yun et al., GRL, 2007) for localized large deformation that cannot be explained by polynomial fitting.

  2. Principles underlying sensory map topography in primary visual cortex.

    PubMed

    Kremkow, Jens; Jin, Jianzhong; Wang, Yushi; Alonso, Jose M

    2016-05-01

    The primary visual cortex contains a detailed map of the visual scene, which is represented according to multiple stimulus dimensions including spatial location, ocular dominance and stimulus orientation. The maps for spatial location and ocular dominance arise from the spatial arrangement of thalamic afferent axons in the cortex. However, the origins of the other maps remain unclear. Here we show that the cortical maps for orientation, direction and retinal disparity in the cat (Felis catus) are all strongly related to the organization of the map for spatial location of light (ON) and dark (OFF) stimuli, an organization that we show is OFF-dominated, OFF-centric and runs orthogonal to ocular dominance columns. Because this ON-OFF organization originates from the clustering of ON and OFF thalamic afferents in the visual cortex, we conclude that all main features of visual cortical topography, including orientation, direction and retinal disparity, follow a common organizing principle that arranges thalamic axons with similar retinotopy and ON-OFF polarity in neighbouring cortical regions. PMID:27120164

  3. 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.

  4. The propagation of internal undular bores over variable topography

    NASA Astrophysics Data System (ADS)

    Grimshaw, R.; Yuan, C.

    2016-10-01

    In the coastal ocean, large amplitude, horizontally propagating internal wave trains are commonly observed. These are long nonlinear waves and can be modelled by equations of the Korteweg-de Vries type. Typically they occur in regions of variable bottom topography when the variable-coefficient Korteweg-de Vries equation is an appropriate model. Of special interest is the situation when the coefficient of the quadratic nonlinear term changes sign at a certain critical point. This case has been widely studied for a solitary wave, which is extinguished at the critical point and replaced by a train of solitary waves of the opposite polarity to the incident wave, riding on a pedestal of the original polarity. Here we examine the same situation for an undular bore, represented by a modulated periodic wave train. Numerical simulations and some asymptotic analysis based on Whitham modulation equations show that the leading solitary waves in the undular bore are destroyed and replaced by a developing rarefaction wave supporting emerging solitary waves of the opposite polarity. In contrast the rear of the undular bore emerges with the same shape, but with reduced wave amplitudes, a shorter overall length scale and moves more slowly.

  5. 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 .

  6. Lithospheric structure of Venus from gravity and topography

    NASA Astrophysics Data System (ADS)

    Jiménez-Díaz, Alberto; Ruiz, Javier; Kirby, Jon F.; Romeo, Ignacio; Tejero, Rosa; Capote, Ramón

    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.

  7. HESS Opinions "Topography driven conceptual modelling (FLEX-Topo)"

    NASA Astrophysics Data System (ADS)

    Savenije, H. H. G.

    2010-12-01

    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 complicated 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 commentary, a new approach is proposed that tries to find the middle way between complex distributed and simple lumped modelling approaches. Here we try to find the right level of simplification while avoiding over-simplification. Paraphrasing Einstein, the maxim is: make a model as simple as possible, but not simpler than that. The approach presented 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. The essence of the approach is that the model structure is made dependent on a limited number of landscape classes in which the topography is the main driver, but which can include geological, geomorphological or land-use classification. These classes are then represented by lumped conceptual models that act in parallel. The advantage of this approach over a fully distributed conceptualisation is that it retains maximum simplicity while taking into account observable landscape characteristics.

  8. HESS Opinions "Topography driven conceptual modelling (FLEX-Topo)"

    NASA Astrophysics Data System (ADS)

    Savenije, H. H. G.

    2010-07-01

    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 complicated 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 commentary, a new model approach is proposed that tries to find the middle way between complex distributed and simple lumped modelling approaches. Here we try to find the right level of simplification while avoiding over-simplification. Paraphrasing Einstein, the maxim is: make a model as simple as possible, but not simpler than that. The approach presented 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. The essence of the approach is that the model structure is made dependent on a limited number of landscape classes in which the topography is the main driver, but which can include geological, geomorphological or land-use classification. These classes are then represented by lumped conceptual models that act in parallel. The advantage of this approach over a fully distributed conceptualisation is that it retains maximum simplicity while taking into account observable landscape characteristics.

  9. 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.

  10. 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.

  11. Anomalous sea surface structures as an object of statistical topography.

    PubMed

    Klyatskin, V I; Koshel, K V

    2015-06-01

    By exploiting ideas of statistical topography, we analyze the stochastic boundary problem of emergence of anomalous high structures on the sea surface. The kinematic boundary condition on the sea surface is assumed to be a closed stochastic quasilinear equation. Applying the stochastic Liouville equation, and presuming the stochastic nature of a given hydrodynamic velocity field within the diffusion approximation, we derive an equation for a spatially single-point, simultaneous joint probability density of the surface elevation field and its gradient. An important feature of the model is that it accounts for stochastic bottom irregularities as one, but not a single, perturbation. Hence, we address the assumption of the infinitely deep ocean to obtain statistic features of the surface elevation field and the squared elevation gradient field. According to the calculations, we show that clustering in the absolute surface elevation gradient field happens with the unit probability. It results in the emergence of rare events such as anomalous high structures and deep gaps on the sea surface almost in every realization of a stochastic velocity field. PMID:26172788

  12. Skylab earth resources experiment package /EREP/ - Sea surface topography experiment

    NASA Technical Reports Server (NTRS)

    Vonbun, F. O.; Marsh, J. G.; Mcgoogan, J. T.; Leitao, C. D.; Vincent, S.; Wells, W. T.

    1976-01-01

    The S-193 Skylab radar altimeter was operated in a round-the-world pass on Jan. 31, 1974. The main purpose of this experiment was to test and 'measure' the variation of the sea surface topography using the Goddard Space Flight Center (GSFC) geoid model as a reference. This model is based upon 430,000 satellite and 25,000 ground gravity observations. Variations of the sea surface on the order of -40 to +60 m were observed along this pass. The 'computed' and 'measured' sea surfaces have an rms agreement on the order of 7 m. This is quite satisfactory, considering that this was the first time the sea surface has been observed directly over a distance of nearly 35,000 km and compared to a computed model. The Skylab orbit for this global pass was computed using the Goddard Earth Model (GEM 6) and S-band radar tracking data, resulting in an orbital height uncertainty of better than 5 m over one orbital period.

  13. 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.

  14. Morphology, topography, and optics of the orthokeratology cornea

    NASA Astrophysics Data System (ADS)

    Faria-Ribeiro, Miguel; Belsue, Rafael Navarro; López-Gil, Norberto; González-Méijome, José Manuel

    2016-07-01

    The goal of this work was to objectively characterize the external morphology, topography, and optics of the cornea after orthokeratology (ortho-k). A number of 24 patients between the ages of 17 and 30 years (median=24 years) were fitted with Corneal Refractive Therapy® contact lenses to correct myopia between -2.00 and -5.00 diopters (D) (median=-3.41 D). A classification algorithm was applied to conduct an automatic segmentation based on the mean local curvature. As a result, three zones (optical zone, transition zone, and peripheral zone) were delimited. Topographical analysis was provided through global and zonal fit to a general ellipsoid. Ray trace on partially customized eye models provided wave aberrations and retinal image quality. Monozone topographic description of the ortho-k cornea loses accuracy when compared with zonal description. Primary (C40) and secondary (C60) spherical aberration (SA) coefficients for a 5-mm pupil increased 3.68 and 19 times, respectively, after the treatments. The OZ area showed a strong correlation with C40 (r=-0.49, p<0.05) and a very strong correlation with C60 (r=0.78, p<0.01). The OZ, as well as the TZ, areas did not correlate with baseline refraction. The increase in the eye's positive SA after ortho-k is the major factor responsible for the decreased retinal optical quality of the unaccommodated eye.

  15. 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.

  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. Snow, topography, and the diurnal cycle in streamflow

    USGS Publications Warehouse

    Lundquist, J.D.; Knowles, N.; Dettinger, M.; Cayan, D.

    2002-01-01

    Because snowmelt processes are spatially complex, point measurements, particularly in mountainous regions, are often inadequate to resolve basin-scale characteristics. Satellite measurements provide good spatial sampling but are often infrequent in time, particularly during cloudy weather. Fortunately, hourly measurements of river discharge provide another widely available, but as yet underutilized, source of information, providing direct information on basin output at a fine temporal scale. The hour of maximum discharge recorded each day reflects the travel time between peak melt and the time most water reaches the gauge. Traditional theories, based on numerical models of melt-water percolation through a snowpack and localized, small-basin observations, report that the hour of daily maximum flow becomes earlier as the snowpack thins and matures, reflecting shorter travel times for surface melt to reach the base of the snowpack. However, an examination of hourly discharge from 100 basins in the Western United States, ranging in size from 1.3 km2 to 10,813 km2, reveals a more complex situation. The sequences of seasonal evolution of the hour of maximum discharge are unique to each basin, but within a given basin are remarkably consistent between years, regardless of the size of the snowpack. This seems to imply that basin topography strongly influences the timing of peak flow. In most of the basins examined, at the end of the melt season, the hour of maximum discharge shifts to later in the day, reflecting increased travel times as the snowline retreats to higher elevations.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Interferometric estimation of ice sheet motion and topography

    NASA Technical Reports Server (NTRS)

    Joughlin, Ian; Kwok, Ron; Fahnestock, Mark; Winebrenner, Dale; Tulaczyk, Slawek; Gogenini, Prasad

    1997-01-01

    With ERS-1/2 satellite radar interferometry, it is possible to make measurements of glacier motion with high accuracy and fine spatial resolution. Interferometric techniques were applied to map velocity and topography for several outlet glaciers in Greenland. For the Humboldt and Petermann glaciers, data from several adjacent tracks were combined to make a wide-area map that includes the enhanced flow regions of both glaciers. The discharge flux of the Petermann glacier upstream of the grounding line was estimated, thereby establishing the potential use of ERS-1/2 interferometric data for monitoring ice-sheet discharge. Interferograms collected along a single track are sensitive to only one component of motion. By utilizing data from ascending and descending passes and by making a surface-parallel flow assumption, it is possible to measure the full three-dimensional vector flow field. The application of this technique for an area on the Ryder glacier is demonstrated. Finally, ERS-1/2 interferograms were used to observe a mini-surge on the Ryder glacier that occurred in autumn of 1995.

  3. Neuronal polarity selection by topography-induced focal adhesion control.

    PubMed

    Ferrari, Aldo; Cecchini, Marco; Serresi, Michela; Faraci, Paolo; Pisignano, Dario; Beltram, Fabio

    2010-06-01

    Interaction between differentiating neurons and the extracellular environment guides the establishment of cell polarity during nervous system development. Developing neurons read the physical properties of the local substrate in a contact-dependent manner and retrieve essential guidance cues. In previous works we demonstrated that PC12 cell interaction with nanogratings (alternating lines of ridges and grooves of submicron size) promotes bipolarity and alignment to the substrate topography. Here, we investigate the role of focal adhesions, cell contractility, and actin dynamics in this process. Exploiting nanoimprint lithography techniques and a cyclic olefin copolymer, we engineered biocompatible nanostructured substrates designed for high-resolution live-cell microscopy. Our results reveal that neuronal polarization and contact guidance are based on a geometrical constraint of focal adhesions resulting in an angular modulation of their maturation and persistence. We report on ROCK1/2-myosin-II pathway activity and demonstrate that ROCK-mediated contractility contributes to polarity selection during neuronal differentiation. Importantly, the selection process confined the generation of actin-supported membrane protrusions and the initiation of new neurites at the poles. Maintenance of the established polarity was independent from NGF stimulation. Altogether our results imply that focal adhesions and cell contractility stably link the topographical configuration of the extracellular environment to a corresponding neuronal polarity state. PMID:20304485

  4. Shuttle Radar Topography Mission - New Products in 2005

    USGS Publications Warehouse

    ,

    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.

  5. Data acquisition time constraints in elevation mapping corneal topography

    NASA Astrophysics Data System (ADS)

    Baron, William S.; Baron, Sandra F.

    1997-05-01

    Elevation mapping corneal topography instruments provide an array of x, y, z data points describing the corneal surface. An advantage of elevation mapping instruments is their ability to calculate the 3D data array strictly from the instrument's geometry and calibration data; no assumptions about the corneal surface itself are needed. However, uncompensated eye movements can affect accuracy. Longitudinal eye movements occur along the z axis, due to pulmonary and cardiac pulsations. Eye rotations due to saccades and drifts are normal occurrences, as are translational body movements. An analysis of eye and body movements at the cornea's surface indicates a nearly linear relationship between data acquisition times of less than 33 msec, and the possible change in elevation at a point referenced to an instrument axis. The proportionality constant is expected to vary by a factor of about six over the range of clinical patients, since eye and body movements are exaggerated in juvenile patients, geriatric patients, and patients with poor vision. The analysis estimates an elevation change due to rotation and longitudinal translation of the eye of up to +/- 285 micrometers in 33 msec within the clinical population. This analysis indicates that when a topographer's acquisition time is greater than 100 microsecond(s) ec (during which an apparent elevation change of up to 1.0 micrometers may occur) testing on static objects may not provide a realistic measure of an instrument's clinical performance.

  6. 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.

  7. Global Resurfacing on Venus: Implications on Plume Motion and Topography

    NASA Astrophysics Data System (ADS)

    Stein, C.; Hansen, U.

    2008-09-01

    ABSTRACT A global resurfacing event is supposed to have taken place on Venus (1; 2). Today, however,Venus is a one-plate planet, i.e. the complete surface is covered by one immobile plate. Such a behaviour is also observed in numerical mantle convection models with variable viscosity. Moresi and Solomatov (3) presented a 2D study of mantle convection with a strong temperature dependence and an additional stress dependence of the viscosity. While the strong temperature dependence causes a cold, rigid and immobile surface atop the convective cycle in the planet's mantle, the additional stress dependence leads to deformation zones in the so-called stagnant lid. By using a 3D study Trompert and Hansen (4) also showed that in this way pieces of the surface are mobilised and take part in the convective cycle. The amount of surface subducted and the temporal evolution of the system depend on the strength of the stress dependence. With increasing stress dependence the surface is more strongly weakened (5) and subduction events occur more rapidly (6). Thus we find that for a low stress dependence sporadic subduction events of the complete surface interrupt otherwise stagnant lid convection. The effect of the subduction of cold, rigid material on both the plume motion and the surface topography is investigated.

  8. 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

  9. Urban topography for flood modeling by fusion of OpenStreetMap, SRTM and local knowledge

    NASA Astrophysics Data System (ADS)

    Winsemius, Hessel; Donchyts, Gennadii; Eilander, Dirk; Chen, Jorik; Leskens, Anne; Coughlan, Erin; Mawanda, Shaban; Ward, Philip; Diaz Loaiza, Andres; Luo, Tianyi; Iceland, Charles

    2016-04-01

    Topography data is essential for understanding and modeling of urban flood hazard. Within urban areas, much of the topography is defined by highly localized man-made features such as roads, channels, ditches, culverts and buildings. This results in the requirement that urban flood models require high resolution topography, and water conveying connections within the topography are considered. In recent years, more and more topography information is collected through LIDAR surveys however there are still many cities in the world where high resolution topography data is not available. Furthermore, information on connectivity is required for flood modelling, even when LIDAR data are used. In this contribution, we demonstrate how high resolution terrain data can be synthesized using a fusion between features in OpenStreetMap (OSM) data (including roads, culverts, channels and buildings) and existing low resolution and noisy SRTM elevation data using the Google Earth Engine platform. Our method uses typical existing OSM properties to estimate heights and topology associated with the features, and uses these to correct noise and burn features on top of the existing low resolution SRTM elevation data. The method has been setup in the Google Earth Engine platform so that local stakeholders and mapping teams can on-the-fly propose, include and visualize the effect of additional features and properties of features, which are deemed important for topography and water conveyance. These features can be included in a workshop environment. We pilot our tool over Dar Es Salaam.

  10. 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.

  11. Isostatic and dynamic support of high topography on a North Atlantic passive margin

    NASA Astrophysics Data System (ADS)

    Kathrine Pedersen, Vivi; Huismans, Ritske S.; Moucha, Robert

    2016-04-01

    Substantial controversy surrounds the origin and recent evolution of high topography along passive continental margins in the North Atlantic, with suggested age of formation ranging from early Paleozoic Caledonian orogenesis to Neogene uplift of a Mesozoic peneplain. Here we focus on the well-documented high passive margin in southwestern Scandinavia, and quantify the relative contributions of crustal isostasy and dynamic topography in controlling the present topography. We find that most topography is compensated by the crustal structure, suggesting a topographic age related to ~400 Myr old Caledonian orogenesis. In addition, we infer that dynamic uplift (~300 m) has rejuvenated existing topography locally in the coastal region within the last ~10 Myr due to mantle convection. Such uplift has, in combination with a general eustatic sea-level fall and concurrent erosion-driven isostatic rock-column uplift, the potential to increase erosion of coastal-near regions and explain observations that have traditionally been interpreted in favor of the peneplain uplift model. We conclude that high topography along the Scandinavian margin cannot represent remnants of a peneplain uplifted within the last ~20 Myr. Topography must have been high since the Caledonian orogeny.

  12. Global dynamic topography observations reveal limited influence of large-scale mantle flow

    NASA Astrophysics Data System (ADS)

    Hoggard, M. J.; White, N.; Al-Attar, D.

    2016-06-01

    Convective circulation of the Earth's mantle maintains some fraction of surface topography that varies with space and time. Most predictive models show that this dynamic topography has peak amplitudes of about +/-2 km, dominated by wavelengths of 104 km. Here, we test these models against our comprehensive observational database of 2,120 spot measurements of dynamic topography that were determined by analysing oceanic seismic surveys. These accurate measurements have typical peak amplitudes of +/-1 km and wavelengths of approximately 103 km, and are combined with limited continental constraints to generate a global spherical harmonic model, the robustness of which has been carefully tested and benchmarked. Our power spectral analysis reveals significant discrepancies between observed and predicted dynamic topography. At longer wavelengths (such as 104 km), observed dynamic topography has peak amplitudes of about +/-500 m. At shorter wavelengths (such as 103 km), significant dynamic topography is still observed. We show that these discrepancies can be explained if short-wavelength dynamic topography is generated by temperature-driven density anomalies within a sub-plate asthenospheric channel. Stratigraphic observations from adjacent continental margins show that these dynamic topographic signals evolve quickly with time. More rapid temporal and spatial changes in vertical displacement of the Earth's surface have direct consequences for fields as diverse as mantle flow, oceanic circulation and long-term climate change.

  13. Modeling the impact of topography on seismic amplification at regional scale

    NASA Astrophysics Data System (ADS)

    Shafique, Muhammad; Anggraeni, Dita; Bakker, Wim; van der Meijde, Mark

    2010-05-01

    The intensity of earthquake triggered ground shaking is influenced by the characteristics of earthquake source, medium and site effects. These site effects are often not included in the regional ground shaking models, especially the local topography. It is being experimentally proved and noticed during many previous earthquakes, that topography has significant impact on variation of ground shaking and subsequent building damages. Majority of the previous studies investigating the topographic impact on seismic response are limited to synthetic environments or isolated hills. This study deals with exploring the impact of topography on variation of ground shaking caused by the 2005 Kashmir earthquake, at a regional scale. With the proliferation of remote sensing technologies, digital elevation models (DEMs) are freely and readily available at medium resolution, and with global cover. DEMs derived from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), with 30m resolution, and Shuttle Radar Topography Mission (SRTM), with 90m resolution, can therefore be utilized to model and predict the impact of topography on seismic response, also quickly after a seismic event. The topography of the 2005 Kashmir earthquake affected area is derived from ASTER and SRTM DEMs and analyzed using a 3D spectral finite element code (SPECFEM3D). SPECFEM3D takes into account the seismic source parameters, medium and topography to generate shake maps and earthquake simulations. The ground shaking simulations and peak ground acceleration maps were generated initially assuming the homogenous ground surface and later by including the topography to assess the role of topography in seismic amplification. Topography derived from ASTER and SRTM DEMs were simulated separately to predict the impact of DEM resolution on computed ground shaking simulations and maps. The preliminary result from the model simulations shows that seismic waves were dispersed at topographic

  14. 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.

  15. Rapid fibroblast adhesion to 27nm high polymer demixed nano-topography.

    PubMed

    Dalby, M J; Giannaras, D; Riehle, M O; Gadegaard, N; Affrossman, S; Curtis, A S G

    2004-01-01

    It is well known that many cell types react strongly to micro-topography. It is rapidly becoming clear than cells will also react to nano-topography. Polymer demixing is a rapid and low-cost chemical method of producing nano-topography. This manuscript investigates human fibroblast response to 27nm high nano-islands produced by polymer demixing. Cell spreading, cytoskeleton, focal adhesion and Rac localisation were studied. The results showed that an initial rapid adhesion and cytoskeletal formation on the islands at 4 days of culture gave way to poorly formed contacts and vimentin cytoskeleton at 30 days of culture. PMID:14580911

  16. Understanding the mechanisms of solid-water reactions through analysis of surface topography.

    PubMed

    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 (d(2)/d(3)) and the ratio of the rate of loss of sites with one neighbor versus three neighbors (d(1)/d(3)). 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 d(1)/d(3) and d(2)/d(3) 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 d(1)/d(3) and d(2)/d(3) 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

  17. X-Ray Topography of Tetragonal Lysozyme Grown by the Temperature-Controlled Technique

    NASA Technical Reports Server (NTRS)

    Stojanoff, V.; Siddons, D. P.; Monaco, Lisa A.; Vekilov, Peter; Rosenberger, Franz

    1997-01-01

    Growth-induced defects in lysozyme crystals were observed by white-beam and monochromatic X-ray topography at the National Synchrotron Light Source (NSLS) at the Brookhaven National Laboratory (BNL). The topographic methods were non-destructive to the extent that traditional diffraction data collection could be performed to high resolution after topography. It was found that changes in growth parameters, defect concentration as detected by X-ray topography, and the diffraction quality obtainable from the crystals were all strongly correlated. In addition, crystals with fewer defects showed lower mosaicity and higher diffraction resolution as expected.

  18. Cancellation of singularities in SAR for curved flight paths and non-flat topography

    NASA Astrophysics Data System (ADS)

    Homan, Andrew

    2014-08-01

    We consider a mathematical model of synthetic aperture radar with a known, possibly non-flat, topography. In this context we consider the problem of recovering the wavefront set of the ground reflectivity, given radar data measured along a curved flight path. We show that if singularities are located at ‘mirror points,’ then the resulting data may be smooth; in effect, the singularities ‘cancel.’ With a flat topography, these mirror points are always discrete, but we show that in a non-flat topography there may be infinite families of mirror points.

  19. Resurfacing events on Venus: Implications on plume dynamics and surface topography

    NASA Astrophysics Data System (ADS)

    Stein, C.; Fahl, A.; Hansen, U.

    2010-01-01

    Global resurfacing events explain the relatively young and uniformly aged surface of Venus. In numerical models featuring these events a variety of plume classes occur ranging from strong, stable to smaller, wind-driven upwellings. We investigate this plume dynamics in a 3D Cartesian geometry paying special attention to the surface topography. While the stable upwellings of the stagnant-lid phase correlate with an elevation of the surface, the wind-driven upwellings of the resurfacing phase do not necessarily correlate with a positive topography signal. We rather observe that a thick plate can dominate the topography above upwellings.

  20. 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

  1. 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

  2. On the chronology and topography of bacterial cell division.

    PubMed

    Vicente, M; Palacios, P; Dopazo, A; Garrido, T; Pla, J; Aldea, M

    1991-01-01

    Gene products that play a role in the formation of cell septum should be expected to be endowed with a set of specific properties. In principle, septal proteins should be located at the cell envelope. The expression of division genes should ensure the synthesis of septal proteins at levels commensurate with the needs of cell division at different rates of cell duplication. We have results indicating that some fts genes located within the 2.5-min cluster in the Escherichia coli chromosome conform to these predictions.

  3. A magmatic probe of dynamic topography beneath western North America

    NASA Astrophysics Data System (ADS)

    Klöcking, 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

  4. Fascicular Topography of the Human Median Nerve for Neuroprosthetic Surgery.

    PubMed

    Delgado-Martínez, Ignacio; Badia, Jordi; Pascual-Font, Arán; Rodríguez-Baeza, Alfonso; Navarro, Xavier

    2016-01-01

    One of the most sought-after applications of neuroengineering is the communication between the arm and an artificial prosthetic device for the replacement of an amputated hand or the treatment of peripheral nerve injuries. For that, an electrode is placed around or inside the median nerve to serve as interface for recording and stimulation of nerve signals coming from the fascicles that innervate the muscles responsible for hand movements. Due to the lack of a standard procedure, the electrode implantation by the surgeon is strongly based on intuition, which may result in poor performance of the neuroprosthesis because of the suboptimal location of the neural interface. To provide morphological data that can aid the neuroprosthetic surgeon with this procedure, we investigated the fascicular topography of the human median nerve along the forearm and upper arm. We first performed a description of the fascicular content and branching patterns along the length of the arm. Next we built a 3D reconstruction of the median nerve so we could analyze the fascicle morphological features in relation to the arm level. Finally, we characterized the motor content of the median nerve fascicles in the upper arm. Collectively, these results indicate that fascicular organization occurs in a short segment distal to the epicondyles and remains unaltered until the muscular branches leave the main trunk. Based on our results, overall recommendations based on electrode type and implant location can be drawn to help and aid the neuroprosthetic procedure. Invasive interfaces would be more convenient for the upper arm and the most proximal third of the forearm. Epineural electrodes seem to be most suitable for the forearm segment after fascicles have been divided from the main trunk. PMID:27445660

  5. 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.

  6. Lung Cancer Mortality and Topography: A Xuanwei Case Study

    PubMed Central

    Ren, Hongyan; Cao, Wei; Chen, Gongbo; Yang, Junxing; Liu, Liqun; Wan, Xia; Yang, Gonghuan

    2016-01-01

    The epidemic of lung cancer in Xuanwei City, China, remains serious despite the reduction of the risk of indoor air pollution through citywide stove improvement. The main objective of this study was to characterize the influences of topography on the spatiotemporal variations of lung cancer mortality in Xuanwei during 1990–2013. Using the spatially empirical Bayes method, the smoothed mortality rate of lung cancer was obtained according to the mortality data and population data collected from the retrospective survey (1990–2005) and online registration data (2011–2013). Spatial variations of the village-level mortality rate and topographic factors, including the relief degree of land surface (RDLS) and dwelling conditions (VDC), were characterized through spatial autocorrelation and hotspot analysis. The relationship between topographic factors and the epidemic of lung cancer was explored using correlation analysis and geographically weighted regression (GWR). There is a pocket-like area (PLA) in Xuanwei, covering the clustered villages with lower RDLS and higher VDC. Although the villages with higher mortality rate (>80 per 105) geographically expanded from the center to the northeast of Xuanwei during 1990–2013, the village-level mortality rate was spatially clustered, which yielded a persistent hotspot area in the upward part of the PLA. In particular, the epidemic of lung cancer was closely correlated with both RDLS and VDC at the village scale, and its spatial heterogeneity could be greatly explained by the village-level VDC in the GWR model. Spatiotemporally featured lung cancer mortality in Xuanwei was potentially influenced by topographic conditions at the village scale. PMID:27164122

  7. Effects of topography and atmospheric structure on volcano infrasound

    NASA Astrophysics Data System (ADS)

    Marcillo, O. E.; Johnson, J. B.

    2009-12-01

    Proper interpretation of infrasonic waves produced by volcanic explosions requires understanding of weather and topographic effects. We have studied infrasound produced by two different volcanoes (Kilauea and Tungurahua) to determine the influence of topographic and atmospheric conditions on the infrasonic records corresponding to several weeks of eruptive activity. This analysis is necessary to understand and correct for phase and amplitude responses in order to properly perform waveform modeling. For instance, these corrections are necessary to obtain a better estimate of volume flux from the volcanic vent. The first case study is a dataset acquired during June of 2008 at Kilauea volcano in Hawaii, focused on the active Halemaumau Vent. Several days of infrasonic tremor were recorded by a 3-station infrasound network. These records show a strong influence of wind and topography in one of the three stations of the network. This station was located 2370 m from the vent, at a comparable distance to the other stations, but line of sight to the vent was obstructed by a 50-meter high crater edge, which introduced diffraction effects. Periods when wind blew in the vent-station direction are correlated with increase in infrasonic energy in the 0.5 - 1 Hz bandwidth. The second case focuses on a campaign conducted in June 2009 at Tungurahua Volcano, Ecuador. This study implemented two infrasonic arrays located on the flanks of the volcano 6000m north of the vent and on the flanks of an adjacent hill, 11,500m northeast. Compared to the proximal array a distinctive attenuation is evident at certain frequencies (0.5-1.5 Hz) at the distal array. This degree of attenuation is time-variant and is mostly likely related to changing atmospheric structure. An alternative explanation for the apparent spectral differences between near and far stations (and their evolution over time) is a complex (and changing) source geometry due to non-compact sources.

  8. Anatomic and Compression Topography of the Lesser Occipital Nerve

    PubMed Central

    Pietramaggiori, Giorgio; Scherer, Saja

    2016-01-01

    Background: The surgical treatment of occipital headaches focuses on the greater, lesser, and third occipital nerves. The lesser occipital nerve (LON) is usually transected with relatively limited available information regarding the compression topography thereof and how such knowledge may impact surgical treatment. Methods: Eight fresh frozen cadavers were dissected focusing on the LON in relation to 3 clinically relevant compression zones. The x axis was a line drawn through the occipital protuberance (OP) and the y axis, the posterior midline (PM). In addition, a prospectively collected cohort of 36 patients who underwent decompression of the LON is presented with their clinical results, including migraine headache index scores. Results: The LON was found in compression zone 1, with a mean of 7.8 cm caudal to the OP and 6.3 cm lateral to the PM. The LON was found at the midpoint of compression zone 2, with an average of 5.5 cm caudal to the OP and 6.2 cm lateral to the PM. At compression zone 3, the medial-most LON branch was located approximately 1 cm caudal to the OP and 5.35 cm lateral to the PM, whereas the lateral-most branch was identified 1 cm caudal to the OP and 6.5 cm lateral to the PM. Of the 36 decompression patients analyzed, only 5 (14%) required neurectomy as the remainder achieved statistically significant improvements in migraine headache index scores postoperatively. Conclusion: The knowledge of LON anatomy can aid in nerve dissection and preservation, thereby leading to successful outcomes without requiring neurectomy. PMID:27257569

  9. 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 cells · mm(-2), and a temporal area with lower densities (38,000-39,000 cells · mm(-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 cycles · degree(-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.

  10. Fascicular Topography of the Human Median Nerve for Neuroprosthetic Surgery

    PubMed Central

    Delgado-Martínez, Ignacio; Badia, Jordi; Pascual-Font, Arán; Rodríguez-Baeza, Alfonso; Navarro, Xavier

    2016-01-01

    One of the most sought-after applications of neuroengineering is the communication between the arm and an artificial prosthetic device for the replacement of an amputated hand or the treatment of peripheral nerve injuries. For that, an electrode is placed around or inside the median nerve to serve as interface for recording and stimulation of nerve signals coming from the fascicles that innervate the muscles responsible for hand movements. Due to the lack of a standard procedure, the electrode implantation by the surgeon is strongly based on intuition, which may result in poor performance of the neuroprosthesis because of the suboptimal location of the neural interface. To provide morphological data that can aid the neuroprosthetic surgeon with this procedure, we investigated the fascicular topography of the human median nerve along the forearm and upper arm. We first performed a description of the fascicular content and branching patterns along the length of the arm. Next we built a 3D reconstruction of the median nerve so we could analyze the fascicle morphological features in relation to the arm level. Finally, we characterized the motor content of the median nerve fascicles in the upper arm. Collectively, these results indicate that fascicular organization occurs in a short segment distal to the epicondyles and remains unaltered until the muscular branches leave the main trunk. Based on our results, overall recommendations based on electrode type and implant location can be drawn to help and aid the neuroprosthetic procedure. Invasive interfaces would be more convenient for the upper arm and the most proximal third of the forearm. Epineural electrodes seem to be most suitable for the forearm segment after fascicles have been divided from the main trunk. PMID:27445660

  11. Lung Cancer Mortality and Topography: A Xuanwei Case Study.

    PubMed

    Ren, Hongyan; Cao, Wei; Chen, Gongbo; Yang, Junxing; Liu, Liqun; Wan, Xia; Yang, Gonghuan

    2016-01-01

    The epidemic of lung cancer in Xuanwei City, China, remains serious despite the reduction of the risk of indoor air pollution through citywide stove improvement. The main objective of this study was to characterize the influences of topography on the spatiotemporal variations of lung cancer mortality in Xuanwei during 1990-2013. Using the spatially empirical Bayes method, the smoothed mortality rate of lung cancer was obtained according to the mortality data and population data collected from the retrospective survey (1990-2005) and online registration data (2011-2013). Spatial variations of the village-level mortality rate and topographic factors, including the relief degree of land surface (RDLS) and dwelling conditions (VDC), were characterized through spatial autocorrelation and hotspot analysis. The relationship between topographic factors and the epidemic of lung cancer was explored using correlation analysis and geographically weighted regression (GWR). There is a pocket-like area (PLA) in Xuanwei, covering the clustered villages with lower RDLS and higher VDC. Although the villages with higher mortality rate (>80 per 10⁵) geographically expanded from the center to the northeast of Xuanwei during 1990-2013, the village-level mortality rate was spatially clustered, which yielded a persistent hotspot area in the upward part of the PLA. In particular, the epidemic of lung cancer was closely correlated with both RDLS and VDC at the village scale, and its spatial heterogeneity could be greatly explained by the village-level VDC in the GWR model. Spatiotemporally featured lung cancer mortality in Xuanwei was potentially influenced by topographic conditions at the village scale. PMID:27164122

  12. 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 cells · mm(-2), and a temporal area with lower densities (38,000-39,000 cells · mm(-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 cycles · degree(-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

  13. Mantle flow and dynamic topography associated with slab window opening

    NASA Astrophysics Data System (ADS)

    Guillaume, Benjamin; Moroni, Monica; Funiciello, Francesca; Martinod, Joseph; Faccenna, Claudio

    2010-05-01

    A slab window is defined as an 'hole' in the subducting lithosphere. In the classical view, slab windows develop where a spreading ridge intersects a subduction zone. The main consequences of this phenomenon are the modifications of the physical, chemical and thermal conditions in the backarc mantle that in turn affect the tectonic and magmatic evolution of the overriding plate. In this work, we perform dynamically self-consistent mantle-scale laboratory models, to evaluate how the opening of a window in the subducting panel influences the geometry and the kinematics of the slab, the mantle circulation pattern and, finally, the overriding plate dynamic topography. The adopted setup consists in a two-layer linearly viscous system simulating the roll-back of a fixed subducting plate (simulated using silicone putty) into the upper mantle (simulated using glucose syrup). Our experimental setting is also characterized by a constant-width rectangular window located at the center of a laterally confined slab, modeling the case of the interaction of a trench-parallel spreading ridge with a wide subduction zone. We find that the geometry and the kinematics of the slab are only minorly affected by the opening of a slab window. On the contrary, slab induced mantle circulation, quantified using Feature Tracking image analysis technique, is strongly modified and produces a peculiar non-isostatic topographic signal on the overriding plate. Assuming that our modeling results can be representative of the natural behavior of subduction zones, we compare them to the Patagonian subduction zone finding that anomalous backarc volcanism that developed since middle Miocene could result from the lateral flowage of subslab mantle, and that part of the Patagonian uplift could be dynamically supported.

  14. 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.

  15. 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

  16. 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

  17. 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.

  18. 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.

  19. 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, ...

  20. 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.

  1. 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

  2. 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.

  3. Ultra-high degree spectral modelling of Earth and planetary topography

    NASA Astrophysics Data System (ADS)

    Rexer, Moritz; Hirt, Christian

    2016-04-01

    New methods for ultra-high degree spherical harmonic analyses and syntheses have been developed and studied over the past years. The focus group "High-resolution Gravity Modelling", established in 2013 at TU Munich, has implemented ultra-high degree spectral modelling techniques and used successfully to transform high-resolution topography grids of Earth, Moon and Mars into spherical harmonics. For Earth, a new set of 1 arc-min topography models, developed by our group and released under the name Earth2014, was expanded into a spherical harmonic series to degree 10,800. For the 15 arc-sec resolution SRTM15_plus topography and bathymetry, a spectral resolution of degree 43,200 was achieved. For Moon and Mars, topography grids from laser altimetry were harmonically analysed up to degree ~46,000. The spectral representations of the topography grids presented in this contribution are required in the context of spectral gravity forward modelling with ultra-high degree, where the topographic potential is computed as a function of the spherical harmonic series of the topography and its integer powers. References: Hirt, C., and M. Rexer (2015) Earth2014: 1 arc-min shape, topography, bedrock and ice-sheet models - available as gridded data and degree-10,800 spherical harmonics, International Journal of Applied Earth Observation and Geoinformation 39, 103-112, doi:10.1016/j.jag.2015.03.001. Rexer, M. and C. Hirt (2015), Ultra-high degree surface spherical harmonic analysis using the Gauss-Legendre and the Driscoll/Healy quadrature theorem and application to planetary topography models of Earth, Moon and Mars. Surveys in Geophysics 36(6), 803-830, doi: 10.1007/s10712-015-9345-z.

  4. 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.

  5. The effect of cataract surgery on imaging optic nerve head topography with the Heidelberg Retina Tomograph.

    PubMed

    Falck, Aura A K; Saarela, Ville

    2012-06-14

    Purpose. To determine whether phacoemulsification cataract surgery with intraocular lens (IOL) implantation interferes with measuring optic nerve head (ONH) topography using the Heidelberg Retina Tomograph (HRT). Methods. The study population consisted of 31 women and 12 men aged 63-81 years with no previous history of eye diseases, surgery, laser procedures, or medication. The patients underwent first eye cataract surgery for senile cataract. The HRT II with software version 1.6 was used to obtain 3-dimensional images of the ONH as a part of a comprehensive ocular examination. The quality of the HRT image was assessed using topography standard deviation (TSD). Topography measurements are considered to be unreliable if TSD is more than 50 µm. Re-examination took place 1 month after surgery. Results. Before surgery, the topography measurements were unreliable in 35% (15/43) of the eyes; in 3 of these cases, ONH topography could not be calculated at all. One month after cataract surgery, the ONH topography could be calculated in all eyes and only one displayed unreliable topography measurements. The mean TSD was 40 µm before and 22 µm after surgery when calculated for all eyes with measurable topographies. The change in TSD was statistically significant (p<0.0005). The image alignment between the HRT examinations before and after surgery was excellent in 67% (26/39). Magnification changes occurred in 21% (8/39). Conclusions. Phacoemulsification cataract surgery with IOL implantation improves the image quality of the HRT. However, because of magnification changes and image misalignment, HRT follow-up of the ONH after cataract surgery is often unreliable.

  6. 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.

  7. Mapping of statistical characteristics of topography on Mars with MOLA data

    NASA Astrophysics Data System (ADS)

    Kreslavsky, M. A.; Head, J. W.

    2003-04-01

    Mars Orbiter Laser Altimeter (MOLA) produced a huge set of precise measurements of Mars surface elevation with uniform 0.3 km spacing along tracks. We use this data set to study statistical characteristics of the martian topography at the scale from hundreds meters to tens of kilometers. Here we give a summary of our published and new results on mapping of statistical characteristics of topography for the purposes of geomorphology and understanding of surface formation and alteration processes. The interquartile widths of the differential-slope- or curvature-frequency distributions are used as measures of the surface roughness at a series of scales. The Hurst exponent quantifies the scale dependence of roughness. The normalized median curvature characterizes the prevalence of concave or convex topography. The normalized median differential slope being a measure of the asymmetry of the slope-frequency distribution, characterizes the north - south slope asymmetry. All maps clearly show the latitudinal trend. High-latitude areas (from the polar deposits edges to 60 deg latitude) are characterized by lower subkilometer-scale roughness, higher Hurst exponent and stronger prevalence of concave topography than the equatorial zone (within 30 deg). The transitional zones (from 30 to 60 deg) are characterized by transitional values of roughness and Hurst exponent, by prevalence of convex topography, and by noticeable slope asymmetry: the equator-facing slopes are steeper. The roughness and Hurst exponent also shows obvious correlation with geological units. The maps shows also some anomalous regions related to distribution of specific surficial deposits. For example, convex topography prevails for giant polygons; eastern part of Daedalia Planum has anomalous prevalence of concave topography and strong slope asymmetry; south-eastern part of Arabia Terra has slope asymmetry and prevalence of convex topography; the hematite deposit has an anomalous signature in all maps.

  8. Bottom-up topography assembly into 3D porous scaffold to mediate cell activities.

    PubMed

    Cheng, Delin; Hou, Jie; Hao, Lijing; Cao, Xiaodong; Gao, Huichang; Fu, Xiaoling; Wang, Yingjun

    2016-08-01

    Native cells live in a three-dimensional (3D) extracellular matrix (ECM) capable of regulating cell activities through various physical and chemical factors. Designed topographies have been well proven to trigger significant difference in cell behaviours. However, present topographies are almost all constructed on two-dimensional (2D) substrates like discs and films, which are far from features like 3D and porosity required in application like bone repair. Here we bottom-up assembled poly(lactic-co-glycolic acid)/calcium carbonate (PLGA/CC) microspheres with superficial porous topography intactly into a 3D porous scaffold. Because the scaffold was obtained through a mild technique, the bioactivity of released BMP-2 was well retained. Mouse bone marrow mesenchymal stem cells (mMSCs) were cultured on produced scaffolds having different 3D topographies. It turned out that osteogenic differentiation of mMSCs did respond to the 3D topographies, while proliferation didn't. Gene expression of αv and β1 integrins revealed that adhesion was supposed to be the underlying mechanism for osteogenic response. The study provides insight into enhancing function of practical scaffolds by elaborate topography design. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1056-1063, 2016.

  9. On the observability of bottom topography from measurements of tidal sea surface height

    NASA Astrophysics Data System (ADS)

    Zaron, Edward D.

    2016-06-01

    The question of whether features of the ocean bottom topography can be identified from measurements of water level is investigated using a simplified one-dimensional barotropic model. Because of the nonlinear dependence of the sea surface height on the water depth, a linearized analysis is performed concerning the identification of a Gaussian bump within two specific depth profiles, (1) a constant depth domain, and, (2) a constant depth domain adjoining a near-resonant continental shelf. Observability is quantified by examining the estimation error in a series of identical-twin experiments varying data density, tide wavelength, assumed (versus actual) topographic correlation scale, and friction. For measurements of sea surface height that resolve the scale of the topographic perturbation, the fractional error in the bottom topography is approximately a factor of 10 larger than the fractional error of the sea surface height. Domain-scale and shelf-scale resonances may lead to inaccurate topography estimates due to a reduction in the effective number of degrees of freedom in the dynamics, and the amplification of nonlinearity. A realizability condition for the variance of the topography error in the limit of zero bottom depth is proposed which is interpreted as a bound on the fractional error of the topography. Appropriately designed spatial covariance models partly ameliorate the negative impact of shelf-scale near-resonance, and highlight the importance of spatial covariance modeling for bottom topography estimation.

  10. Insect wing membrane topography is determined by the dorsal wing epithelium.

    PubMed

    Belalcazar, Andrea D; Doyle, Kristy; Hogan, Justin; Neff, David; Collier, Simon

    2013-01-01

    The Drosophila wing consists of a transparent wing membrane supported by a network of wing veins. Previously, we have shown that the wing membrane cuticle is not flat but is organized into ridges that are the equivalent of one wing epithelial cell in width and multiple cells in length. These cuticle ridges have an anteroposterior orientation in the anterior wing and a proximodistal orientation in the posterior wing. The precise topography of the wing membrane is remarkable because it is a fusion of two independent cuticle contributions from the dorsal and ventral wing epithelia. Here, through morphological and genetic studies, we show that it is the dorsal wing epithelium that determines wing membrane topography. Specifically, we find that wing hair location and membrane topography are coordinated on the dorsal, but not ventral, surface of the wing. In addition, we find that altering Frizzled Planar Cell Polarity (i.e., Fz PCP) signaling in the dorsal wing epithelium alone changes the membrane topography of both dorsal and ventral wing surfaces. We also examined the wing morphology of two model Hymenopterans, the honeybee Apis mellifera and the parasitic wasp Nasonia vitripennis. In both cases, wing hair location and wing membrane topography are coordinated on the dorsal, but not ventral, wing surface, suggesting that the dorsal wing epithelium also controls wing topography in these species. Because phylogenomic studies have identified the Hymenotera as basal within the Endopterygota family tree, these findings suggest that this is a primitive insect character.

  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 μm and mean distance between peaks (RSm) ranging from 89.7 to 18.6 μm 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 μm and RSm ranging from 53.9 to 39.3 μm. 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.

  12. 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.

  13. 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.

  14. 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 SΔq 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.

  15. 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

  16. Vertical transport of particulate organic matter regulated by fjord topography

    NASA Astrophysics Data System (ADS)

    Erlandsson, Carina P.

    2008-03-01

    The deepwater in many areas with restricted water exchange suffers from low oxygen concentrations due to degradation of organic matter. The objective of this study was to investigate how topography may influence the vertical transport, Fc, of particulate organic matter, POM, to the deepwater. A conceptual/analytical model for Fc was developed covering the combination of the three possible sources of POM/nutrients to an enclosed area; the coastal water, local supply, and nutrient rich local deepwater. The mathematical formulation of the conceptual model includes several factors describing to which degree various physical mechanisms in the fjord are influencing Fc. The model consists of submodels for the different sources of POM/nutrients. A one-dimensional process oriented numerical model was used to test the conceptual model. Restricted water exchange with the coastal water led to decreased import of POM and thereby decreased vertical transport, Fc, of coastal POM. The contribution to Fc by local input of nutrients to the surface layer was described by a function of the residence time of the water above sill level, Tsw and the time Tp it takes for POM produced in the surface layer to settle below sill level. The recirculation of POM produced due to basin water renewals was shown to be a function of several factors: The relation between the depth of photic zone, Hp and the sill depth, Ht, the vertical velocity of the rising nutrient rich water mass versus the settling velocity of POM, etc. The results based on the conceptual submodels agreed well with the results from the process oriented numerical model. Methods to identify the trophic state of coastal waters, and also simple models to calculate the effect of a local point source, can be found in literature. However, using the model developed in this paper the effects of nutrient enrichment from different sources can be quantified in a simple and more efficient way than earlier. The model can thus be used to

  17. The Ocean Surface Topography SENTINEL-6/JASON-CS Mission

    NASA Astrophysics Data System (ADS)

    Cullen, R.

    2015-12-01

    The Sentinel-6/Jason-CS mission 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; NASA for the US payload and launcher procurement in addition to funding US science opportunities; EC for funding the operations and participation in funding (with EUMETSAT) for the 2nd satellite; NOAA are expected to provide US ground stations & operations services; CNES for mission expertise and provision of the POD service. 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 Commission funding is also fully secure. The design is based on a platform derived from CryoSat-2 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

  18. Evaluation of a new model of mask topography effects

    NASA Astrophysics Data System (ADS)

    Pierrat, Christophe

    2010-09-01

    A new method for simulating mask topography effects is described. A model comprising a set of functions is generated based on the results of test patterns simulated using rigorous mask simulation. The functions are combined with the thin mask diffraction pattern in order to create a modeled thick mask diffraction pattern. The mask diffraction pattern is subsequently used in the lithosimTM simulation tool to generate the wafer image. Results are described for 1D and 2D test structures. The 1D test structures is a line and space test pattern where the line is set at 40nm width and the space is varied from 40nm to 1000nm. The illumination setting chosen was a TE polarized dipole illumination with a pole distance of 0.9 and a pole radius of 0.01. First the accuracy of the simulator itself was verified using thin mask calculation and comparing the data to another simulator. The intensity profiles are virtually identical. The RMS of the difference between the two plots is 8E-05. Next the model is compared to the rigorous calculation. The RMS of the difference between the two plots is 3E-03. The standard deviation of the CD difference between the model and the rigorous calculation, calculated for 5 thresholds (0.1, 0.11, 0.12, 0.13, and 0.14) and for all the structures, is 0.38nm. We also demonstrate that the mask model can be used with different optical settings by showing an example of two additional defocus values with an identical RMS of 3E-03. For the 2D test pattern made of a dense contact array, the mask fields are computed using rigorous calculation and compared to the model. The difference between the fields is within the error of the rigorous calculation. The resulting wafer images are almost identical. No re-scaling of the data was applied to either the mask fields or the wafer images.

  19. French Polynesia Hotspot Swells Explained By Dynamic Topography

    NASA Astrophysics Data System (ADS)

    Adam, C.; Yoshida, M.; Isse, T.; Suetsugu, D.; Shiobara, H.; Sugioka, H.; Kanazawa, T.; Fukao, Y.; Barruol, G.

    2007-12-01

    Situated on the South Pacific Superswell, French Polynesia is a region characterized by numerous geophysical anomalies among which a high volcanism concentration. Seven hotspots are required to explain the observed chains, volcanism ages and geochemical trends. Many open questions still remain on the origin of these hotspot chains: are they created by passive uplift of magma due to discontinuities in the structure of the lithosphere or by the ascent of mantle plumes? In this case, at which depth do these plumes initiate in the mantle? Many geophysical observations (bathymetry, gravity, magnetism, volcanism ages..) are used to understand the unique phenomenon occurring on this region. The most useful information may come from tomography models since they provide a 3D view of the mantle. Until recently, the tomography models over the region were quite inaccurate because of the sparse location of the seismic stations. The deployment of two new seismic stations networks (BBOBS and temporary island stations) has lately remedied this failing. The resulting tomography model obtained through the inversion of Rayleigh waves provides the most accurate view of the shallowest part of the mantle (depths ≤ 240 km) beneath French Polynesia. Indeed, for the first time the accuracy of a tomography model is good enough to provide information about plume phenomenology in this complex region. In order to quantify the plumes effect on the seafloor, we compute the dynamic topography through an instantaneous flow model. The general trend of the observed depths anomalies (highs and lows) is well recovered. For example the amplitude, location and extension of the swells associated with the Society, Macdonald and Rarotonga are accurately described by the dynamic model. We also find that dynamic uplift is associated with the Tuamotu archipelago which means that a part of the observed swell is due to the present day action of plumes. Since no volcanism ages are available over this chain

  20. 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

  1. Neogene Topography And Precipitation Patterns Of The Central Anatolian Plateau

    NASA Astrophysics Data System (ADS)

    Mulch, A.; Mikes, T.; Schemmel, F.; Rojay, B.

    2010-12-01

    Long-term stable isotope records of terrestrial environments represent increasingly important tools for tectonic, paleoaltimetric, and paleoclimatic reconstructions within continental interiors. A rapidly growing number of studies within the Earth’s major mountain ranges demonstrates that the growth of topography and orogenic plateaus profoundly influences local, regional, and hemispheric climate and hence precipitation patterns while regional surface uplift patterns are intimately linked to plate-scale geodynamic processes. In contrast, such records are almost absent for the Near East and the Turkish-Iranian plateau, an important topographic element in the Alpine-Himalayan chain and an area most likely to be strongly affected by future climate change and water scarcity. Our objective is to assess the role of orographic factors that have governed the distribution (and isotopic composition) of precipitation across the central Anatolian plateau (CAP, Turkey) from the Neogene to recent. Such data are fundamental for our understanding of the geodynamic and sedimentary history of orogenic plateaus in general and for the role of surface uplift along the plateau margins in the Pontide and Tauride mountains. We present oxygen, carbon, and hydrogen isotope data from Neogene-to-recent fluvio-lacustrine and pedogenic environments, stream and lake waters of the CAP with the ultimate aim of reconstructing past precipitation changes, plateau aridification and ideally Neogene surface uplift histories. Our approach is to cross-calibrate modern patterns of isotopes (oxygen and hydrogen) in precipitation with pedogenic carbonate oxygen and carbon isotope data across topographic barriers that today strongly control the distribution of rainfall along the plateau margins and within the plateau interior. We then compare these patterns with Miocene-to-Pleistocene lacustrine and pedogenic records to assess a) the role of late Neogene (ca. 8-0 Ma) surface uplift in the Taurus mountains

  2. The influence of deep mantle heterogeneity on the rhythms and scales of surface topography evolution

    NASA Astrophysics Data System (ADS)

    Arnould, Maëlis; Coltice, Nicolas; Flament, Nicolas

    2016-04-01

    Earth's surface, the interface between external processes and internal dynamics (lithosphere motions and mantle convection), is continuously reorganised. A large part of Earth's topography is generated by mantle motions and lithospheric stresses [1], which impacts for instance the global sea-level, the dynamics of sedimentary basins and the geoid. Studying how surface topography evolves in both space and time thus not only provides information on the rhythms and scales of evolution of those processes, but would also be a tool for the study of the mantle motions and properties from which it originates [2]. In this study, we propose to characterise the spatial and temporal scales of evolution of surface topography in 2D spherical annulus numerical models of mantle convection developing a plate-like behaviour. We use the geodynamical code StagYY [3] to first determine a mantle convection regime generating a surface topography with Earth-like amplitudes and realistic mantle dynamics at first order (e.g. high Rayleigh number, reasonable lithosphere thickness, pseudo-plastic lithosphere rheology generating plate tectonics). We then use this convection regime to investigate how the presence of stable deep-rooted thermochemical heterogeneities influence the rhythms of evolution of surface topography. We analyse our results to identify how the timescales of evolution are connected with the lengthscales of topography, in light of the tectonic histories produced by the models. References: [1] M. Gurnis, Long-term controls of eustatic and epeirogenic motions by mantle convection, GSA Today, 2(7):141-157, 1992. [2] B.H. Hager, R.W. Clayton, M.A. Richards, R.P. Comer, and A.M. Dziewonski, Lower mantle heterogeneity, dynamic topography and the geoid, Nature, 313:541-545, 1985. [3] J.W. Hernlund and P.J. Tackley, Modeling mantle convection in the spherical annulus, Phys. Earth Planet. Interiors, 171(1):48-54, 2008.

  3. 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

  4. Determining relative contributions of vegetation and topography to burn severity from LANDSAT imagery.

    PubMed

    Wu, Zhiwei; He, Hong S; Liang, Yu; Cai, Longyan; Lewis, Bernard J

    2013-10-01

    Fire is a dominant process in boreal forest landscapes and creates a spatial patch mosaic with different burn severities and age classes. Quantifying effects of vegetation and topography on burn severity provides a scientific basis on which forest fire management plans are developed to reduce catastrophic fires. However, the relative contribution of vegetation and topography to burn severity is highly debated especially under extreme weather conditions. In this study, we hypothesized that relationships of vegetation and topography to burn severity vary with fire size. We examined this hypothesis in a boreal forest landscape of northeastern China by computing the burn severity of 24 fire patches as the difference between the pre- and post-fire Normalized Difference Vegetation Index obtained from two Landsat TM images. The vegetation and topography to burn severity relationships were evaluated at three fire-size levels of small (<100 ha, n = 12), moderate (100-1,000 ha, n = 9), and large (>1,000 ha, n = 3). Our results showed that vegetation and topography to burn severity relationships were fire-size-dependent. The burn severity of small fires was primary controlled by vegetation conditions (e.g., understory cover), and the burn severity of large fires was strongly influenced by topographic conditions (e.g., elevation). For moderate fires, the relationships were complex and indistinguishable. Our results also indicated that the pattern trends of relative importance for both vegetation and topography factors were not dependent on fire size. Our study can help managers to design fire management plans according to vegetation characteristics that are found important in controlling burn severity and prioritize management locations based on the relative importance of vegetation and topography.

  5. 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

  6. Molecular response of Escherichia coli adhering onto nanoscale topography

    PubMed Central

    2012-01-01

    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. PMID:23078758

  7. Recognizing magnetic structures by present and future radio telescopes with Faraday rotation measure synthesis

    NASA Astrophysics Data System (ADS)

    Beck, R.; Frick, P.; Stepanov, R.; Sokoloff, D.

    2012-07-01

    Faraday telescope”. The combination of data from the Low Frequency Array (LOFAR, at low frequencies) and the Expanded Very Large Array (EVLA, at high frequencies) appears to be a promising approach for the recognition of magnetic structures on all scales. The addition of data at intermediate frequencies from the Westerbork Synthesis Radio Telescope (WSRT) or the Giant Meterwave Radio Telescope (GMRT) would fill the gap between the LOFAR and EVLA frequency ranges. The Global Magneto-Ionic Medium Survey (GMIMS), planned with several single-dish telescopes at low angular resolution, will also provide good scale recognition and high resolution in Faraday space.

  8. Numerical modeling and analysis of the effect of Greek complex topography on tornado genesis

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    Tornadoes have been reported in Greece over the last decades in specific sub-geographical areas and have been associated with strong synoptic forcing. It is well known that meteorological conditions over Greece are affected at various scales by the significant variability of topography, the Ionian Sea at the west and the Aegean Sea at the east. However, there is still uncertainty regarding topography's importance on tornadic generation and development. The aim of this study is to investigate the role of topography in significant tornado genesis events that were triggered under strong synoptic scale forcing over Greece. Three tornado events that occurred over the last years in Thiva (Boeotia, 17 November 2007), Vrastema (Chalkidiki, 12 February 2010) and Vlychos (Lefkada, 20 September 2011) have been selected for numerical experiments. These events were associated with synoptic scale forcing, while their intensity was T4-T5 (Torro scale) and caused significant damage. The simulations were performed using the non-hydrostatic Weather Research and Forecasting model (WRF), initialized with ECMWF gridded analyses, with telescoping nested grids that allow the representation of atmospheric circulations ranging from the synoptic scale down to the meso scale. In the experiments the topography of the inner grid was modified by: (a) 0% (actual topography) and (b) -100% (without topography). The aim was to determine whether the occurrence of tornadoes - mainly identified by various severe weather instability indices - could be indicated by modifying topography. The main utilized instability variables concerned the Bulk Richardson number shear (BRN), the energy helicity index (EHI), the storm-relative environmental helicity (SRH) and the maximum convective available potential energy (MCAPE, for parcel with maximum theta-e). Additional a verification of model was conducted for every sensitivity experiment accompanied with analysis absolute vorticity budget. Numerical simulations

  9. How to approximate viscoelastic dynamic topographies of stagnant lid planetary bodies?

    NASA Astrophysics Data System (ADS)

    Dumoulin, Caroline; Čadek, Ondřej; Choblet, Gaël

    2013-04-01

    Planetary mantles are viscoelastic media. However, since numerical models of thermal convection in a viscoelastic spherical shell are still very challenging, most of the studies concerning dynamic topography of planetary surfaces generated by mantle convection use one of the following simplified rheological set-up: i) IVF (instantaneous viscous flow), ii) viscous body with a free surface, or iii) hybrid methods combining viscous deformation and elastic filtering of the topography. Justifications for the use of such approximations instead of a fully viscoelastic rheology have been made on the basis of simple tests with step-like viscosity structures, with small to moderate viscosity contrasts. However, because the rheology of planetary materials is thermally activated, the radial stratification of viscosity is more likely to be a continuous function of depth, and global viscosity contrasts might be very large. In our study, we systematically compare viscoelastic dynamic topography induced by an internal load to topographies generated by the three different simplified approaches listed above using a realistic viscosity profile for a stagnant lid associated to the lithosphere of a one plate planete. To this purpose, we compute response functions of surface topography and geoid using three different semi-spectral models that all include self-gravitation: a) a linear Maxwell body with a pseudo free upper surface, b) a viscous body with a pseudo free upper surface, and c) a viscous body with a free-slip condition at the surface. Results obtained with this last model (IVF) can then be filtered using the elastic thin shell approximation: the effective elastic thickness then corresponds to the elastic thickness that is needed to fit the viscoelastic topography with an elastic filtering of the IVF topography. We show that the effective elastic thickness varies strongly with the degree of the load, with the depth of the load, and with the duration of the loading. These

  10. Week Long Topography Study of Young Adults Using Electronic Cigarettes in Their Natural Environment

    PubMed Central

    Roundtree, K. A.; Difrancesco, A. G.; Nonnemaker, J. M.; Lee, Y. O.

    2016-01-01

    Results of an observational, descriptive study quantifying topography characteristics of twenty first generation electronic nicotine delivery system users in their natural environment for a one week observation period are presented. The study quantifies inter-participant variation in puffing topography between users and the intra-participant variation for each user observed during one week of use in their natural environment. Puff topography characteristics presented for each user include mean puff duration, flow rate and volume for each participant, along with descriptive statistics of each quantity. Exposure characteristics including the number of vaping sessions, total number of puffs and cumulative volume of aerosol generated from ENDS use (e-liquid aerosol) are reported for each participant for a one week exposure period and an effective daily average exposure. Significant inter-participant and intra-participant variation in puff topography was observed. The observed range of natural use environment characteristics is used to propose a set of topography protocols for use as command inputs to drive machine-puffed electronic nicotine delivery systems in a controlled laboratory environment. PMID:27736944

  11. Biodiversity of Jinggangshan Mountain: the importance of topography and geographical location in supporting higher biodiversity.

    PubMed

    Zhou, Ting; Chen, Bao-Ming; Liu, Gang; Huang, Fang-Fang; Liu, Jin-Gang; Liao, Wen-Bo; Wang, Ying-Yong; Ren, Si-Jie; Chen, Chun-Quan; Peng, Shao-Lin

    2015-01-01

    Diversity is mainly determined by climate and environment. In addition, topography is a complex factor, and the relationship between topography and biodiversity is still poorly understood. To understand the role of topography, i.e., altitude and slope, in biodiversity, we selected Jinggangshan Mountain (JGM), an area with unique topography, as the study area. We surveyed plant and animal species richness of JGM and compared the biodiversity and the main geographic characteristics of JGM with the adjacent 4 mountains. Gleason's richness index was calculated to assess the diversity of species. In total, 2958 spermatophyte species, 418 bryophyte species, 355 pteridophyte species and 493 species of vertebrate animals were recorded in this survey. In general, the JGM biodiversity was higher than that of the adjacent mountains. Regarding topographic characteristics, 77% of JGM's area was in the mid-altitude region and approximately 40% of JGM's area was in the 10°-20° slope range, which may support more vegetation types in JGM area and make it a biodiversity hotspot. It should be noted that although the impact of topography on biodiversity was substantial, climate is still a more general factor driving the formation and maintenance of higher biodiversity. Topographic conditions can create microclimates, and both climatic and topographic conditions contribute to the formation of high biodiversity in JGM.

  12. Three-dimensional finite difference viscoelastic wave modelling including surface topography

    NASA Astrophysics Data System (ADS)

    Hestholm, Stig

    1999-12-01

    I have undertaken 3-D finite difference (FD) modelling of seismic scattering fromfree-surface topography. Exact free-surface boundary conditions for arbitrary 3-D topographies have been derived for the particle velocities. The boundary conditions are combined with a velocity-stress formulation of the full viscoelastic wave equations. A curved grid represents the physical medium and its upper boundary represents the free-surface topography. The wave equations are numerically discretized by an eighth-order FD method on a staggered grid in space, and a leap-frog technique and the Crank-Nicholson method in time. I simulate scattering from teleseismic P waves by using plane incident wave fronts and real topography from a 60 x 60 km area that includes the NORESS array of seismic receiver stations in southeastern Norway. Synthetic snapshots and seismogr