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1

The Global Multi-Resolution Topography (GMRT) Synthesis  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

2

GMRT Observations of Microquasar V4641 Sgr  

E-print Network

We report the GMRT observations of V4641 Sgr during the May 2002 outburst at radio frequencies of 610 and 244 MHz. This is the lowest frequency radio detection of this source. The present low frequency radio observations clearly showed spectral evolution from the optically thick to thin state. This behavior is broadly consistent with the expanding bubble model. However, the flux densities observed at lower frequencies are much higher than predicted by this model. In the conical jet model, this discrepancy could be reconciled.

C. H. Ishwara-Chandra; A. Pramesh Rao

2005-12-05

3

Giant metrewave radio telescope (GMRT) - Scientific objectives and design aspects  

Microsoft Academic Search

A description is presented of the giant meterwave radio telescope (GMRT) being set up in India about 80 km north of Pune. The telescope will serve as a frontline research facility for astronomy and astrophysics. One of the important aims of the telescope is to search for the highly redshifted 21-cm line radiation from primordial neutral hydrogen clouds in order

G. Swarup

1990-01-01

4

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

SciTech Connect

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.

Wientjes, F.B.; Nanninga, N. (Univ. of Amsterdam (Netherlands))

1989-06-01

5

A real-time software backend for the GMRT  

Microsoft Academic Search

The new era of software signal processing has a large impact on radio astronomy instrumentation. Our design and implementation\\u000a of a 32 antennae, 33 MHz, dual polarization, fully real-time software backend for the GMRT, using only off-the-shelf components,\\u000a is an example of this. We have built a correlator and a beamformer, using PCI-based ADC cards and a Linux cluster of

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

2010-01-01

6

A software baseband receiver for pulsar astronomy at GMRT  

E-print Network

A variety of pulsar studies, ranging from high precision astrometry to tests for theories of gravity, require high time resolution data. Few such observations at more than two frequencies below 1 GHz are available. Giant Meterwave Radio Telescope (GMRT) has the unique capability to provide such multi-frequency pulsar data at low observation frequencies, but the quality and time resolution of pulsar radio signals is degraded due to dispersion in the inter-stellar medium at these frequencies. Such degradation is usually taken care of by employing specialized digital hardware, which implement coherent dedispersion algorithm. In recent years, a new alternative is provided by the availability of cheap computer hardware. In this approach, the required signal processing is implemented in software using commercially off-the-shelf available computing hardware. This makes such a receiver flexible and upgradeable unlike a hardware implementation. The salient features and the modes of operation of a high time resolution pulsar instrument for GMRT based on this approach is described in this paper. The capability of the instrument is demonstrated by illustrations of test observations. We have obtained the average profile of PSR B1937+21 at 235 MHz for the first time and this profile indicates a scattering timescale of about 300 us. Lastly, the possible future extensions of this concept are discussed.

Bhal Chandra Joshi; Sunil Ramakrishna

2006-11-10

7

GMRT HI observations of the Eridanus group of galaxies  

E-print Network

The GMRT HI 21cm-line observations of galaxies in the Eridanus group are presented. The Eridanus group, at a distance of ~23 Mpc, is a loose group of \\~200 galaxies. The group extends more than 10 Mpc in projection. The velocity dispersion of the galaxies in the group is ~240 km/s. The galaxies are clustered into different sub-groups. The overall population mix of the group is 30% (E+S0) and 70% (Sp+Irr). The observations of 57 Eridanus galaxies were carried out with the GMRT for ~200 hour. HI emission was detected from 31 galaxies. The channel rms of ~1.0 mJy beam^{-1} was achieved for most of the image-cubes made with 4 hour of data. The corresponding HI column density sensitivity (3-sigma) is ~1x10^{20} cm^{-2} for a velocity-width of ~13.4 km/s. The 3-sigma detection limit of HI mass is ~1.2x10^{7} M_sun for a line-width of 50 km/s. Total HI images, HI velocity fields, global HI line profiles, HI mass surface densities, HI disk parameters and HI rotation curves are presented. The velocity fields are analysed separately for the approaching and the receding sides of the galaxies. This data will be used to study the HI and the radio continuum properties, the Tully-Fisher relations, the dark matter halos, and the kinematical and HI lopsidedness in galaxies.

A. Omar; K. S. Dwarakanath

2005-03-24

8

Tracing the merger history of MACS clusters using the GMRT  

E-print Network

Galaxy-cluster merger shocks efficiently accelerate the ambient electrons through diffusive shock acceleration and amplify magnetic field by compressing the Inter Cluster Medium. As a result, such objects produce a significant amount of synchrotron radio emission. Radio halo and Mpc scale peripheral radio relics thus help us to trace back the cluster formation history. To study the dynamical state of the galaxy clusters and their relation to the merging scenario, as a pilot project, we thus observed four suitable candidates from the MACS (Massive Cluster Survey) cluster sample. Observations were carried out simultaneously at 610 and 235 MHz with the GMRT. We observed a rare phenomena in the cluster MACSJ0014.3-3022, which hosts both a peripheral spectacular radio relic and an unusually flat spectrum central giant radio halo of more than 1.5 Mpc dimension. We also report that another cluster MACSJ0152.5-2852 is possibly showing the sign of one of the earliest and young merging system where, we saw a faint 0.5 ...

Paul, S; Intema, H T

2014-01-01

9

Density Isostasy and Topography  

NSDL National Science Digital Library

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

10

No detection of L-band radio emission from SN 2007gr by GMRT  

NASA Astrophysics Data System (ADS)

Sayan Chakraborti (Tata Institute of Fundamental Research, Mumbai, (TIFR)), Poonam Chandra (Univ Virginia and National Radio Astronomical Observatory, Charlottesville), Nirupam Roy (National Centre for Radio Astrophysics (NCRA-TIFR), Pune, and Alak Ray (TIFR) report on the Target of Opportunity observation of SN 2007gr on 2007 Aug 24 by the Giant Metrewave Radio Telescope (GMRT) in the L-band between UT 0200 to 0400.

Ray, Alak K.

2007-08-01

11

Topography measurements and applications  

NASA Astrophysics Data System (ADS)

Based on auto- and cross-correlation functions (ACF and CCF), a new surface parameter called profile (or topography) difference, D s, has been developed for quantifying differences between 2D profiles or between 3D topographies with a single number. When D s = 0, the two compared 2D profiles or 3D topographies must be exactly the same (point by point). A 2D and 3D topography measurement system was established at NIST. This system includes data acquisition stations using a stylus instrument and a confocal microscope, and a correlation program using the proposed parameters D s and the cross-correlation function maximum CCF max. Applications in forensic science and surface metrology are described; those include profile signature measurements for 40 NIST Standard Reference Material (SRM) 2460 standard bullets, and comparisons of profile measurements with four different techniques. An approach to optimizing the Gaussian filter long wavelength cutoff, ?c, is proposed for topography measurements.

Song, Junfeng; Vorburger, Theodore

2006-11-01

12

VizieR Online Data Catalog: Complete 150MHz GMRT source catalogue (Ghosh+, 2012)  

NASA Astrophysics Data System (ADS)

We have observed in GMRT Time Allocation Committee (GTAC) the fields: * I on 2008-01-08 for 11hrs at 153MHz, center(J2000)=05:30:00+60:00:00 * II on 2010-02-07 for 6hrs at 148MHz, center(J2000)=06:00:00+62:12:58 * III on 2010-02-08 for 6hrs at 148MHz, center(J2000)=12:36:49+62:12:58 * IV on 2005-06-15 for 13hrs at 153MHz, center(J2000)=01:36:48+41:24:23 (1 data file).

Ghosh, A.; Prasad, J.; Bharadwaj, S.; Ali, Sk. S.; Chengalur, J. N.

2013-04-01

13

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

14

Prospects for GMRT to Observe Radio Waves from UHE Particles Interacting with the Moon  

E-print Network

Ultra high energy (UHE) particles of cosmic origin impact the lunar regolith and produce radio signals through Askaryan effect, signals that can be detected by Earth based radio telescopes. We calculate the expected sensitivity for observation of such events at the Giant Metrewave Radio Telescope (GMRT), both for UHE cosmic rays (CR) and UHE neutrino interactions. We find that for 30 days of observation time a significant number of detectable events is expected above $10^{20}$ eV for UHECR or neutrino fluxes close to the current limits. Null detection over a period of 30 days will lower the experimental bounds on UHE particle fluxes by magnitudes competitive to both present and future experiments at the very highest energies.

Sukanta Panda; Subhendra Mohanty; Padmanabhan Janardhan; Oscar Stål

2007-08-13

15

Flow Interaction with Topography  

NSDL National Science Digital Library

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

2014-09-14

16

Gallery of Virtual Topography  

NSDL National Science Digital Library

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

Stephen Reynolds

17

The Dawn Topography Investigation  

NASA Technical Reports Server (NTRS)

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.

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

18

Search for 150 MHz radio emission from extrasolar planets in the TIFR GMRT Sky Survey  

NASA Astrophysics Data System (ADS)

The ongoing radio continuum TIFR GMRT Sky Survey (TGSS) using the Giant Metrewave Radio Telescope (GMRT) at 150 MHz offers an unprecedented opportunity to undertake a fairly deep search for low-frequency radio emission from nearby extrasolar planets. Currently TGSS images are available for a little over a steradian, encompassing 175 confirmed exoplanetary systems. We have searched for their radio counterparts in the TGSS (150 MHz), supplemented with a search in the NRAO VLA Sky Survey (NVSS) and the VLA FIRST survey at 1.4 GHz. For 171 planetary systems, we find no evidence of radio emission in the TGSS maps, placing a 3? upper limit between 8.7 mJy and 136 mJy (median ~24.8 mJy) at 150 MHz. These non-detections include the 55 Cnc system for which we place a 3? upper limit of 28 mJy at 150 MHz. Nonetheless, for four of the extrasolar planetary systems, we find TGSS radio sources coinciding with or located very close to their coordinates. One of these is 61 Vir: for this system a large radio flux density was predicted in the scenario involving magnetosphere-ionosphere coupling and rotation-induced radio emission. We also found 150 MHz emissions toward HD 86226 and HD 164509, where strong radio emission can be produced by the presence of a massive satellite orbiting a rapidly rotating planet. We also detected 150 MHz emission within a synthesized beam from 1RXS1609 b, a pre-main-sequence star harboring a ~14 Jupiter mass planet (or a brown dwarf). With a bright X-ray-UV star and a high mass, the planet 1RXS1609 b presents the best characteristics for rotation-induced emissions with high radio power. Deeper high-resolution observations toward these planetary systems are needed to discriminate between the possibilities of background radio-source and radio-loud planets. At 1.4 GHz, radio emission toward the planet-harboring pulsar PSR B1620-26 is detected in the NVSS. Emissions at 1.4 GHz are also detected toward the very-hot-Jupiter WASP-77A b (in the FIRST survey) and the giant planet HD 43197 b in a highly eccentric orbit (in NVSS). We briefly discuss these detections, as well as the non-detection of the vast majority of exoplanets. Full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/562/A108

Sirothia, S. K.; Lecavelier des Etangs, A.; Gopal-Krishna; Kantharia, N. G.; Ishwar-Chandra, C. H.

2014-02-01

19

Ocean Surface Topography from Space  

NSDL National Science Digital Library

Interactive Flash Module about Ocean Surface Topography. Module includes sea surface observations and measurements as well as visuals explanations of the alimetry instruments used to detect surface changes.

Jet Propulsion Laboratory, California Institute of Technology, NASA

20

RADAR Reveals Titan Topography  

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

21

Topography of Io (color)  

NASA Technical Reports Server (NTRS)

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

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

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

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

1997-01-01

22

Density, Isostasy, and Topography  

NSDL National Science Digital Library

Show caption HideA critical component of this activity involves sharing team data with the entire class, done the old-fashioned way on the chalkboard. Details This activity begins with an exploration of a topographic map of the earth, ending with the question: Why is the distribution of topography on the earth bimodal? The students then collect two forms of data. They measure the density of the most common rocks that make up oceanic crust (basalt), continental crust (granite), and the mantle (peridotite). They also measure the density of several different kinds of wood, and how high each kind floats in a tub of water. In each case, they work in teams of two or three and then the entire class shares their data. Based on the data from the wood, they derive an equation that relates the density of the wood to the height at which the block floats in the water - the isostasy equation. They then substitute density values for real rocks into their equation to derive thicknesses for average continental and oceanic crust, and apply their knowledge in order to draw a cross-section of the crust across South America. This activity gives students a real, hands-on and mathematical understanding of the principle of isostasy.

Egger, Anne

23

Global Topography and Tectonic Plates  

NSDL National Science Digital Library

The goal of this activity is to investigate global topographic and tectonic features, especially the tectonic plates and their boundaries. Using a double-page size digital topographic map of the Earth that includes both land and sea floor topography, students are asked to draw plate boundaries, deduce plate motions and interactions, and explore the connections between topography and tectonic processes at the global scale.

David Greene

24

The Shuttle Radar Topography Mission  

Microsoft Academic Search

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

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

2007-01-01

25

The Shuttle Radar Topography Mission  

Microsoft Academic Search

The Shuttle Radar Topography Mission (SRTM), which flew successfully aboard Endeavour in February 2000, is a cooperative project between NASA and the National Imagery and Mapping Agency (NIMA). The mission was designed to use a single-pass radar interferometer to produce a digital elevation model of the Earth's land surface between about 60 degrees north and 56 degrees south latitude. The

T. G. Farr; M. Kobrick

2001-01-01

26

Stem Cell Interaction with Topography  

Microsoft Academic Search

\\u000a The growth and differentiation of stem cells are regulated by biochemical and biophysical cues in the extracellular microenvironment.\\u000a Increasing evidences have shown that substrate topography, one of the biophysical properties of the microenvironment, can\\u000a affect stem cell fate, such as the maintenance of embryonic stem cells and the differentiation of adult and embryonic stem\\u000a cells. The underlying mechanism of how

Benjamin K. K. Teo; Soneela Ankam; Evelyn K. F. Yim

27

Plasma processing for nanostructured topographies  

NASA Astrophysics Data System (ADS)

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

Riedel, Nicholas Alfred

28

Bathymetry, Topography, and Relief Data  

NSDL National Science Digital Library

This extensive site from NOAA's National Geophysical Data Center provides a collection of bathymetry, topography, and relief data from a variety of sources and environments including coastlines, the Great Lakes, and the seafloor. The site also features the National Ocean Service (NOS) hydrographic database. Some images and data can be downloaded at no charge, while others may be purchased on CD-ROM or DVD. The site can be searched for downloadable data using the GEODAS Data Search and Retrieval System. Data products from NOS surveys, including Descriptive Reports (DRs), smooth sheet images, survey data images, textual gridded data, and sidescan sonar mosaics, are available for download using the National Ocean Service Hydrographic Survey Data Map Service, an ArcIMS interactive map and data discovery tool.

Center, National G.; Noaa

29

Venus - Global gravity and topography  

NASA Astrophysics Data System (ADS)

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.

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

1993-05-01

30

The Shuttle Radar Topography Mission  

NASA Technical Reports Server (NTRS)

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

Farr, Tom G.; Kobrick, Mike

2000-01-01

31

Maps of Mars Global Topography  

NASA Technical Reports Server (NTRS)

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.

1999-01-01

32

Sensory properties of menthol and smoking topography  

PubMed Central

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

2011-01-01

33

Predicting dynamic topography from mantle circulation models  

NASA Astrophysics Data System (ADS)

Dynamic topography is anomalous vertical motions of Earth's surface associated with viscous flow in the mantle. Deformable boundaries, such as the surface, CMB and phase transition boundaries, within a fluid (Earth's mantle) are deflected by viscous flow. Denser than average, sinking mantle creates inward deflections of Earth's surface. Equally, upwelling flow creates bulges in the surface; large plumes are commonly thought to produce superswells, such as the anomalously high elevation of Southern Africa. Dynamic topography appears to operate on a number of length scales. Mantle density anomalies estimated from seismic tomography indicate long wavelength dynamic topography at present day of around 2 km amplitude (e.g. Conrand & Husson, 2009) whilst continental scale studies suggest vertical motions of a few hundred metres. Furthermore, time scales must be an important factor to consider when assessing dynamic topography. Stable, dense lower mantle 'piles' may contribute to dynamic surface topography; as they appear stable over reasonably long time scales, long wavelength dynamic topography may be a fairly constant feature over the recent geological past. Shorter wavelength, smaller amplitude dynamic topography may be due to more transient features of mantle convection. Studies on a continental scale reveal shorter term changes in dynamic topography of the order of a few hundred metres (e.g. Roberts & White, 2010; Heine et al., 2010). Understanding dynamic topography is complicated by the fact it is difficult to observe as the signal is often masked by isostatic effects. We use forward mantle convection models with 300 million years of recent plate motion history as the surface boundary condition to generate a present day distribution of density anomalies associated with subducted lithosphere. From the modelled temperature and density fields we calculate the normal stress at or near the surface of the model. As the models generally have a free slip surface where no vertical motion is allowed, an excess or deficit of stress exists near the surface. A pointwise force balance between this stress excess and the weight of rock above is used to calculate the anomalous elevation associated with the stress. Here we present some of the results obtained from mantle circulation models. We look at different ways of predicting dynamic topography, including the depth at which the stress field is calculated and by removing lithospheric density anomalies from the calculation. We also assess the impact of crustal thickness and isostasy on the predictions of dynamic topography.

Webb, Peter; Davies, J. Huw

2013-04-01

34

Dynamic Topography of Oceans and Continents  

NASA Astrophysics Data System (ADS)

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.

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

2004-05-01

35

GMRT observations of the radio source 4C 35.06: precessing jets from a cD galaxy under assembly?  

E-print Network

We report GMRT observation of the strong radio source 4C 35.06, an extended (z=0.047) radio-loud AGN at the center of galaxy cluster Abell 407. The radio map at 610 MHz reveal a striking, helically twisted jet system emanating from an optically faint AGN host. The radio morphology closely resembles the precessing jets of the galactic microquasar SS 433. The optical SDSS images of central region show a complex ensemble of nine galactic condensations within 1 arc minute, embedded in a faint, diffuse stellar halo. This system presents a unique case for studying the formation of a giant elliptical galaxy (cD) at the cluster center.

G, Biju K; P., Sunilkumar; Dhurde, Samir; Bagchi, Joydeep; H., Ishwara-Chandra C; Jacob, Joe

2014-01-01

36

Development of Global Bathymetry and Topography at 15 arc seconds  

NASA Astrophysics Data System (ADS)

The global bathymetry provided at approximately 1 km resolution (SRTM30_PLUS) is used in many scientific studies and is also displayed in Google Earth over most of the oceans where higher resolution data is unavailable. One problem with this compilation is that the ubiquitous abyssal hill fabric, evident in multibeam bathymetry, is poorly resolved at 1 km resolution. In an effort to better resolve seafloor features globally we are developing a 500 m global bathymetry and topography grid following the approach of Smith and Sandwell [1997] and Becker et al., [2009]. Land topography is derived from three sources: hole-filled SRTM 3-arc second topography provided by CGIAR (http://srtm.csi.cgiar.org/), ASTER GDEM (http://www.gdem.aster.ersdac.or.jp/) for latitudes where SRTM us unavailable, and the ICESAT DEM ( http://nsidc.org/data ) for Greenland and Antarctica. Topography of some larger lakes has been included. Ocean bathymetry is based on three data types coming from hundreds of sources. 1) A newly developed altimetry-derived bathymetry is used as the low-resolution (~10 km) shape of the ocean basins between latitudes +/- 81 degrees. This new model uses the latest marine gravity based on all non-repeat orbit altimeters including CryoSat and Envisat. 2) Higher resolution grids have been added from the LDEO Ridge Multibeam Synthesis Project, the JAMSTEC Data Site for Research Cruises, and the NGDC Coastal Relief Model. Arctic bathymetry is mostly from the International Bathymetric Chart of the Oceans (IBCAO) [Jakobsson et al., 2012]. 3) The best resolution comes from a reanalysis of the US multibeam data archived at the National Geophysical Data Center. The main difficulty with gridding the bathymetry data at this higher resolution is that millions of erroneous bathymetric soundings, that were previously hidden by the 1 km median filtering are visible at 500 m resolution. These outliers must be edited using both automated and manual methods. At the meeting we'll report the progress on this new global compilation.

Becker, J. J.; Sandwell, D. T.

2012-12-01

37

Mars topography harmonics and geophysical implications  

NASA Technical Reports Server (NTRS)

The paper describes an improved model of Martian global topography which has been obtained by fitting a sixteenth-degree harmonic series to occultation, radar, spectral, and photogrammetric measurements. Empirical elevation data based on photographic data are used to supplement the observations in areas without data. Values for the mean radius, the mean density, and the displacement of the center of the figure from the center of mass are presented. The reported geometric flattening is too great and the reported dynamic flattening is too small for Mars to be homogeneous and hydrostatic. Maps of the data distribution, global topography, and Bouguer gravity anomaly are interpreted in terms of a crustal thickness map which is consistent with gravity, topography, and recent preliminary Viking seismic results.

Bills, B. G.; Ferrari, A. J.

1978-01-01

38

Localized Gravity/Topography Admittances on Mars  

NASA Technical Reports Server (NTRS)

Admittances from Mars Global Surveyor (MGS) gravity and topography yield estimates of lithosphere thickness on Mars: central Tharsis > 100 km, Alba Patera = 50 km, southern highlands < 20 km (but south polar cap > 50 km). Alba Patera and Elysium Rise are similar structures.

McGovern, Patrick J.; Solomon, Sean C.; Smith, David E.; Zuber, Maria T.; Neumann, Gregory A.; Head, James W.

2000-01-01

39

Virtual Field Trip: Temperate Deciduous Forest Topography  

E-print Network

Virtual Field Trip: Temperate Deciduous Forest #12;Topography #12;Landform and Soils #12;Climate #12;Climate #12;Vegetation Structure #12;Vegetation Structure #12;Disturbance and Forest Growth Rates and Askins 1995 #12;Presettlement forest Clearing for homestead: 1740 Height of forest clearing: 1830 Farm

Hansen, Andrew J.

40

Detecting and quantifying topography in neural maps.  

PubMed

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

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

2014-01-01

41

Ocean Surface Topography from Space - Science  

NSDL National Science Digital Library

This site, from the Jet Propulsion Laboratory at the California Institute of Technology, describes the scientific applications of ocean surface topography from missions such as TOPEX/Poseidon and Jason-1. Other topics include uses of the collected data, such as evaluations of ocean circulation, tides, weather and climate patterns, and other trends.

Laboratory, Jet P.; Nasa

42

The relationship between Martian gravity and topography  

Microsoft Academic Search

The relationship between gravity and topography of various regions of Mars is used to estimate their effective elastic thicknesses Te using direct measurements of line of sight velocity, rather than spherical harmonic coefficients. Estimates of Te vary from 70 km for Tharsis, 29 km for Elysium, to 14.5 km for the southern hemisphere, and show that the thickness of the

Dan McKenzie; David N. Barnett; Dah-Ning Yuan

2002-01-01

43

Gravity and Topography of Moon and Planets  

Microsoft Academic Search

Planetology serves the understanding on the one hand of the solar system and on the other hand, for investigating similarities and differences, of our own planet. While observational evidence about the outer planets is very limited, substantial datasets exist for the terrestrial planets. Radar and optical images and detailed models of gravity and topography give an impressive insight into the

R. Rummel

2004-01-01

44

Links between climate, erosion, uplift, and topography during intracontinental mountain  

E-print Network

Links between climate, erosion, uplift, and topography during intracontinental mountain building a window into understanding how climate influences the erosion and resulting geomorphic and sedimentary signatures of continental topography. Specifically, asymmetric erosion of the Hangay, associated

Watts, A. B. "Tony"

45

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

NASA Astrophysics Data System (ADS)

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

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

2005-10-01

46

The Role of Topography in Glacial Inception  

Microsoft Academic Search

We test the influence of model topography on glacial inception using a coupled atmosphere-slab ocean version of NCAR's Community Climate System Model (CCSM3). Simulations employ a modern orbital configuration and greenhouse gas concentrations representing both recent (year 1990) and hypothetically lower present-day values in accordance with Ruddiman's Early Anthropogenic Hypothesis (240 ppm CO2 and 450 ppb CH4). The model is

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

2009-01-01

47

Topography measurement of specular and diffuse surfaces  

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

48

ATM Coastal Topography-Mississippi, 2001  

USGS Publications Warehouse

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

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

2009-01-01

49

ATM Coastal Topography-Alabama 2001  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Alabama coastline, acquired October 3-4, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface, and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for pre-survey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or first surface topography.

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

2009-01-01

50

Nanoscale Surface Topography to Guide Bone Growth  

E-print Network

Dental Association Foundation) C O L L A B O R A T O R S : Lei Chen, Sheng Lin-Gibson (NIST) G O A LNanoscale Surface Topography to Guide Bone Growth P R O J E C T L E A D E R : Jirun Sun (American tissues in order to improve dental implants and bone restoratives. K E Y A C C O M P L I S H M E N

51

Neural network applications in surface topography  

Microsoft Academic Search

There is an industrial need for the measurement and classification of the topography of engineering surfaces - two-dimensional (2-D) analysis is fast, but limited in the usefulness of the results obtainable whilst the three-dimensional (3-D) approach offers greater scope. Unfortunately, the data analysis step for 3-D data characterisation can be time-consuming, and often requires a skilled metrologist. The approach has

E. Mainsah; D. T. Ndumu

1998-01-01

52

Diffraction imaging (topography) with monochromatic synchrotron radiation  

NASA Technical Reports Server (NTRS)

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

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

1988-01-01

53

Karst Topography: Teacher's Guide and Paper Model  

NSDL National Science Digital Library

This lesson uses paper models to help students understand karst processes, why caves develop in limestone, and how karst topography develops. Introductory materials explain how ground- or surface waters can dissolve limestone, some features of karst landscapes (sinkholes, disappearing streams), and some features of caves (stalagmites, stalactites, flowstone). A teacher's guide provides patterns and instructions for building the models, and a glossary and references are included.

54

EAARL topography: Cape Cod National Seashore  

USGS Publications Warehouse

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.

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

2007-01-01

55

EAARL topography: Assateague Island National Seashore  

USGS Publications Warehouse

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.

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

2007-01-01

56

EAARL topography: Gulf Islands National Seashore: Florida  

USGS Publications Warehouse

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.

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

2007-01-01

57

EAARL topography: Gulf Islands National Seashore: Mississippi  

USGS Publications Warehouse

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.

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

2007-01-01

58

EAARL topography: Thomas Stone National Historic Site  

USGS Publications Warehouse

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.

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

2007-01-01

59

EAARL topography: Gateway National Recreation Area  

USGS Publications Warehouse

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

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

2007-01-01

60

EAARL Topography-Padre Island National Seashore  

USGS Publications Warehouse

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.

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

2007-01-01

61

Evolution of Neogene Dynamic Topography in Africa  

NASA Astrophysics Data System (ADS)

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

Paul, Jonathan; Roberts, Gareth; White, Nicky

2013-04-01

62

Coarsely resolved topography along protein folding pathways  

NASA Astrophysics Data System (ADS)

The kinetic data from the coarse representation of polypeptide torsional dynamics described in the preceding paper [Fernandez and Berry, J. Chem. Phys. 112, 5212 (2000), preceding paper] is inverted by using detailed balance to obtain a topographic description of the potential-energy surface (PES) along the dominant folding pathway of the bovine pancreatic trypsin inhibitor (BPTI). The topography is represented as a sequence of minima and effective saddle points. The dominant folding pathway displays an overall monotonic decrease in energy with a large number of staircaselike steps, a clear signature of a good structure-seeker. The diversity and availability of alternative folding pathways is analyzed in terms of the Shannon entropy ?(t) associated with the time-dependent probability distribution over the kinetic ensemble of contact patterns. Several stages in the folding process are evident. Initially misfolded states form and dismantle revealing no definite pattern in the topography and exhibiting high Shannon entropy. Passage down a sequence of staircase steps then leads to the formation of a nativelike intermediate, for which ?(t) is much lower and fairly constant. Finally, the structure of the intermediate is refined to produce the native state of BPTI. We also examine how different levels of tolerance to mismatches of side chain contacts influence the folding kinetics, the topography of the dominant folding pathway, and the Shannon entropy. This analysis yields upper and lower bounds of the frustration tolerance required for the expeditious and robust folding of BPTI.

Fernández, Ariel; Kostov, Konstantin S.; Berry, R. Stephen

2000-03-01

63

EAARL topography: George Washington Birthplace National Monument  

USGS Publications Warehouse

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.

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

2007-01-01

64

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

65

The VVDS-VLA Deep Field: III. GMRT observations at 610 MHz and the radio spectral index properties of the sub-mJy population  

E-print Network

We present the low frequency (610 MHz) radio source counts of the VVDS-VLA field and investigate the radio spectral index properties of the sub-mJy population. We use new deep (r.m.s.$\\simeq 50$ $\\mu$Jy/beam) observations of the VVDS-VLA field obtained at 610 MHz with the GMRT and matched in resolution (6 arcsec) with already available VLA data at 1.4 GHz on the same field. We find evidence of a change of the dominant population of radio sources below 0.5 mJy (at 1.4 GHz): between 0.15 and 0.5 mJy the median spectral index is significantly flatter ($\\alpha=-0.46\\pm 0.03$) than that of brighter sources ($\\alpha=-0.67\\pm 0.05$). A relevant contribution below 0.5 mJy from a population of flat spectrum low luminosity compact AGNs and radio quiet QSOs could explain this effect. At even fainter flux density, between 0.10 and 0.15 mJy at 1.4 GHz, the median spectral index steepens again ($\\alpha=-0.61\\pm 0.04$) suggesting that the contribution of starburst galaxies becomes important below $\\sim 0.2$ mJy. Finally we present a sample of 58 candidate ultra-steep sources with radio flux density from one to two orders of magnitude lower than any other sample of such objects.

M. Bondi; P. Ciliegi; T. Venturi; D. Dallacasa; S. Bardelli; E. Zucca; R. M. Athreya; L. Gregorini; A. Zanichelli; O. Le Fevre; T. Contini; B. Garilli; A. Iovino; S. Temporin; D. Vergani

2006-11-22

66

Surface topography dependent desorption of alkali halides  

PubMed

Electron-stimulated desorption of the (100)KBr surface has been investigated in vacuum with noncontact atomic force microscopy and mass spectroscopy. It has been found that both desorption components (K and Br) show oscillatory dependence on the electron dose with the oscillation amplitude decaying gradually. These results correspond with periodically varying, as a result of a layer-by-layer desorption, surface topography. It is proposed that the surface terrace edges act as traps for excited F centers diffusing in the crystal. The oscillating density of terrace edges varies surface recombination/reflection rates for the F centers and modulates the balance between surface and bulk deexcitation of the crystal. PMID:10978122

Such; Kolodziej; Czuba; Piatkowski; Struski; Krok; Szymonski

2000-09-18

67

EAARL Coastal Topography - Sandy Hook 2007  

USGS Publications Warehouse

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

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

2008-01-01

68

Welcome to Surface Topography: Metrology and Properties  

NASA Astrophysics Data System (ADS)

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

Leach, Richard

2013-11-01

69

The Shuttle Radar Topography Mission (SRTM): a breakthrough in remote sensing of topography  

Microsoft Academic Search

The Shuttle Radar Topography Mission (SRTM), flown on the Space Shuttle Endeavour on Flight STS-99 and launched on 11 February 2000, will produce digital elevation data of the Earth's land mass between 60 degrees north latitude and 54 degrees south latitude. This data will be at least one order of magnitude more precise in the elevation resolution, and will have

Jakob J. van Zyl

2001-01-01

70

Surface topography evolution and fatigue fracture in polysilicon MEMS structures  

Microsoft Academic Search

This paper presents the results of an experimental study of the micromechanisms of surface topography evolution and fatigue fracture in polysilicon MEMS structures. The initial stages of fatigue are shown to be associated with stress-assisted surface topography evolution and the thickening of SiO2 layers that form on the unpassivated polysilicon surfaces and crack\\/notch faces. The differences in surface topography and

Seyed M. Allameh; Pranav Shrotriya; Alex Butterwick; Stuart B. Brown; Wole O. Soboyejo

2003-01-01

71

Surface topography of the cylindrical gear tooth flanks after machining  

Microsoft Academic Search

The paper presents an analysis of three-dimensional surface topography of side and side out in tooth space flanks of cylindrical\\u000a gear machined after hobbing and chiselling by Fellows method. The parameters and functions of surface topography as well as\\u000a spectral analysis were used. Primary surface topography after extraction of involute tooth profile was analysed. It was found\\u000a that contour maps

Jacek Michalski

2009-01-01

72

Analysis Of Scoliosis By Back Shape Topography  

NASA Astrophysics Data System (ADS)

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

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

1983-07-01

73

EAARL Topography-Colonial National Historical Park  

USGS Publications Warehouse

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.

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

2008-01-01

74

Retrieving lunar topography from multispectral LROC images  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

75

Hydrothermal circulation in fault slots with topography  

NASA Astrophysics Data System (ADS)

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

Titarenko, Sofya; McCaig, Andrew

2014-05-01

76

EAARL Coastal Topography - Northern Gulf of Mexico  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived coastal topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. One objective of this research is to create techniques to survey areas for the purposes of geomorphic change studies following major storm events. The USGS Coastal and Marine Geology Program's National Assessment of Coastal Change Hazards project is a multi-year undertaking to identify and quantify the vulnerability of U.S. shorelines to coastal change hazards such as effects of severe storms, sea-level rise, and shoreline erosion and retreat. Airborne Lidar surveys conducted during periods of calm weather are compared to surveys collected following extreme storms in order to quantify the resulting coastal change. Other applications of high-resolution topography include habitat mapping, ecological monitoring, volumetric change detection, and event assessment. The purpose of this project is to provide highly detailed and accurate datasets of the northern Gulf of Mexico coastal areas, acquired on September 19, 2004, immediately following Hurricane Ivan. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Airborne Advanced Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532 nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking RGB (red-green-blue) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers and an integrated miniature digital inertial measurement unit which provide for sub-meter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system on September 19, 2004. The survey resulted in the acquisition of 3.2 gigabytes of data. The data were processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for pre-survey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of 'last return' elevations.

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

2008-01-01

77

The Influence of Topography on Volatile Transport  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

78

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

NASA Astrophysics Data System (ADS)

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 mountain, lowland, and hybrid synthetic river valleys. To conclude, recommended advances such as multithread channels are discussed along with potential applications.

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

2014-06-01

79

A harmonic analysis of lunar topography  

NASA Technical Reports Server (NTRS)

A global lunar topographic map has been derived from existing earth-based and orbital observations supplemented in areas without data by a linear autocovariance predictor. Of 2592 bins, each 5 deg square, 1380 (64.7% by area) contain at least one measurement. A spherical harmonic analysis to degree 12 yields a mean radius of 1737.53 plus or minus 0.03 km (formal standard error) and an offset of the center of figure of 1.98 plus or minus 0.06 km toward (19 plus or minus 2) deg S, (194 plus or minus 1) deg E. A Bouguer gravity map, derived from a 12-degree free-air gravity model and the present topography data, is presented for an elevation of 100 km above the mean surface. It is confirmed that the low-degree gravity harmonics are determined primarily by surface height variations and only secondarily by lateral density variations.

Bills, B. G.; Ferrari, A. J.

1977-01-01

80

Gravity and topography. [of planet Mars  

NASA Technical Reports Server (NTRS)

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.

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

81

EAARL topography: Fire Island National Seashore  

USGS Publications Warehouse

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).

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

2007-01-01

82

EAARL submarine topography: Biscayne National Park  

USGS Publications Warehouse

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

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

2006-01-01

83

Alongshore currents over variable beach topography  

NASA Astrophysics Data System (ADS)

The nonlinear dynamics of unstable alongshore currents in the nearshore surf zone over variable barred beach topography are studied using numerical experiments. These experiments extend the recent studies of Allen et al. [1996] and Slinn et al. [1998], which utilized alongshore uniform beach topographies by including sinusoidal alongshore variation to shore parallel sandbars. The model involves finite difference solutions to the nonlinear shallow water equations for forced, dissipative, initial value problems and employs periodic boundary conditions in the alongshore direction. Effects of dissipation are modeled by linear bottom friction. Forcing for the alongshore currents is provided by gradients in the radiation stress, which are specified using linear theory and the dissipation function for breaking waves formulated by Thornton and Guza [1983]. Distinct flows develop depending on the amplitude ? and wavelength ? of the topographic variability and the dimensionless parameter Q, the ratio of an advective to a frictional timescale. For Q greater than a critical value QC the flows are linearly stable. For ?Q = QC - Q>0 the flow can be unstable. For small values of ?Q the effect of increasing ?; is to stabilize or regularize the flows and to cause the mean flow to approximately follow contours of constant depth. Equilibrated shear waves develop that propagate along the mean current path at phase speeds and wavelengths that are close to predictions for the most unstable mode from linear theory applied to alongshore-averaged conditions. At intermediate values of ?Q, unsteady vortices form and exhibit nonlinear interactions as they propagate along the mean current path, occasionally merging, pairing, or being shed seaward of the sandbar. Eddies preferentially form in the mean current when approaching alongshore troughs of the sandbar and break free from the mean current when approaching alongshore crests of the sandbar. At the largest values of ?Q examined the resulting flow fields resemble a turbulent shear flow and are less strongly influenced by the alongshore variability in topography. As the amplitude of the alongshore topographic variability increases, alongshore wavenumber-frequency spectra of the across-shore velocity show a corresponding increase in energy at both higher alongshore wavenumbers and over a broader frequency range with significant energy at wavenumbers of topographic variability and harmonics. Across-shore fluxes of mass and momentum generally increase with increasing topographic amplitude and increasing ?Q. Time- and space-lagged correlations of the across-shore velocity show that correlation length scales decrease as topographic perturbation amplitudes increase. Terms from the vorticity equation show that the alongshore variation of the radiation stresses and the value of ?Q are of importance to the flow behavior. Hybrid experiments separating effects of spatially variable forcing and the dynamic influence of topography on time-averaged currents show that the effects are generally comparable with the relative importance of each effect a function of ?Q. The results show that topographic variability has a significant influence on nearshore circulation.

Slinn, Donald N.; Allen, J. S.; Holman, R. A.

2000-07-01

84

Assimilation of altimeter topography into oceanic models  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

85

Electrified viscous thin film flow over topography  

NASA Astrophysics Data System (ADS)

We investigate the gravity-driven flow of a liquid film down an inclined wall with periodic indentations in the presence of a normal electric field. The film is assumed to be a perfect conductor and the bounding air region above is a perfect dielectric. We study the interaction between the electric field and the topography at steady state conditions. Using a long-wave analysis we derive a nonlinear, non-local evolution equation for the thickness of the liquid film and compute steady solutions for flow into a rectangular trench and over a rectangular mound, for example. We demonstrate that the electric field can be used to reduce or completely remove the familiar ridge features seen ahead of a downward step. Boundary integral computations of the full problem are also presented and compared with the long-wave theory.

Papageorgiou, Demetrios; Tseluiko, Dmitri; Blyth, Mark; vanden-Broeck, Jean-Marc

2007-11-01

86

Investigation of the mode of compensation of Venus topography  

NASA Technical Reports Server (NTRS)

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

Morgan, Paul

1986-01-01

87

Edinburgh Research Explorer Detecting and Quantifying Topography in Neural Maps  

E-print Network

for published version: Yarrow, S, Seitz, AR, Seriès, P & Razak, K 2014, 'Detecting and Quantifying Topography date: 14. Jun. 2014 #12;Detecting and Quantifying Topography in Neural Maps Stuart Yarrow1 *, Khaleel A at the scale of individual binaural clusters. Citation: Yarrow S, Razak KA, Seitz AR, Serie`s P (2014

Millar, Andrew J.

88

ASYMPTOTIC SHALLOW WATER MODELS WITH NON SMOOTH TOPOGRAPHIES  

E-print Network

ASYMPTOTIC SHALLOW WATER MODELS WITH NON SMOOTH TOPOGRAPHIES MATHIEU CATHALA Abstract. We present new models to describe shallow water flows over non smooth topographies. The water waves problem with respect to the surface and the bottom parametrizations, we derive a nonlocal shallow water model which

Paris-Sud XI, Université de

89

Breakout SessionIII,Bed-Materialand Bed-TopographyMeasurement  

E-print Network

Breakout SessionIII,Bed-Materialand Bed-TopographyMeasurement: DataNeeds,Uncertainty by each of the represented agencies and uncertainties associated with these data were also discussed measurement methods used in bathymetric surveys of underwater bed topography. These sources of error include

90

Corneal topography matching by iterative registration.  

PubMed

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. PMID:25500860

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

2014-11-01

91

Seismological Modeling of Inner Core Boundary Topography  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

92

Surface Water and Ocean Topography (SWOT) mission  

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

93

Electrified viscous thin film flow over topography  

NASA Astrophysics Data System (ADS)

The gravity-driven flow of a liquid film down an inclined wall with periodic indentations in the presence of a normal electric field is investigated. The film is assumed to be a perfect conductor, and the bounding region of air above the film is taken to be a perfect dielectric. In particular, the interaction between the electric field and the topography is examined by predicting the shape of the film surface under steady conditions. A nonlinear, non-local evolution equation for the thickness of the liquid film is derived using a long-wave asymptotic analysis. Steady solutions are computed for flow into a rectangular trench and over a rectangular mound, whose shapes are approximated with smooth functions. The limiting behaviour of the film profile as the steepness of the wall geometry is increased is discussed. Using substantial numerical evidence, it is established that as the topography steepness increases towards rectangular steps, trenches, or mounds, the interfacial slope remains bounded, and the film does not touch the wall. In the absence of an electric field, the film develops a capillary ridge above a downward step and a slight depression in front of an upward step. It is demonstrated how an electric field may be used to completely eliminate the capillary ridge at a downward step. In contrast, imposing an electric field leads to the creation of a free-surface ridge at an upward step. The effect of the electric field on film flow into relatively narrow trenches, over relatively narrow mounds, and down slightly inclined substrates is also considered.

Tseluiko, D.; Blyth, M. G.; Papageorgiou, D. T.; vanden-Broeck, J.-M.

94

Silk film topography directs collective epithelial cell migration.  

PubMed

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

Lawrence, Brian D; Pan, Zhi; Rosenblatt, Mark I

2012-01-01

95

Video Animation of Ocean Topography From TOPEX/POSEIDON  

NASA Technical Reports Server (NTRS)

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...

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

1993-01-01

96

Topography and Volcanoes on Io (color)  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

1997-01-01

97

New Global Bathymetry and Topography Model Grids  

NASA Astrophysics Data System (ADS)

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

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

2008-12-01

98

Spreading of droplet with insoluble surfactant on corrugated topography  

NASA Astrophysics Data System (ADS)

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

Li, Chunxi; Pei, Jianjun; Ye, Xuemin

2014-09-01

99

Quasi Two-Dimensional Turbulent Flow Over Discontinuous Topography  

NASA Astrophysics Data System (ADS)

Decaying turbulent flows with topography are studied by means of laboratory experiments in a rotating tank and by numerical simulations based on a quasi-two-dimensional model. The basic configuration is a step-like topography dividing the flow domain in deep and shallow regions. The main objectives are: to prove that different domain geometries influence the long-term flow evolution; to show the generation of a final flow configuration; and to examine the physical mechanisms behind the main interactions of simple structures with the topography, like dipoles, in order to explain the final flow distribution.

Tenreiro, M.; Zavala Sansón, L.

2007-05-01

100

Shape, topography, gravity anomalies and tidal deformation of Titan  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

101

Dewetting of evaporating thin films over nanometer-scale topographies  

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

102

Dewetting of evaporating thin films over nanometer-scale topographies.  

PubMed

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. PMID:25122317

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

2014-07-01

103

Basal topography of Kronebreen, NW Svalbard  

NASA Astrophysics Data System (ADS)

Kronebreen is a tidewater outlet glacier draining the icefield Holtedahlfonna, in the Kongsfjord area of NW Svalbard. Like most glaciers in Svalbard, Kronebreen has been in retreat since the first front positions were recorded, with the exception of a brief advance during the surge of the neighboring glacier Kongsvegen around 1948. Kronebreen is one of the fastest non-surging glaciers in Svalbard, with average annual velocities near the calving front of around 450 m/yr. It has not been possible until recently to calculate ice fluxes, however, since the bottom topography of Kronebreen has been unknown. In 2009, ice thickness data were obtained using low frequency radar from helicopter over the heavily crevassed Kronebreen. These new thickness data are combined with surface elevation maps, older ice depth data, and fjord bathymetry data to create an expanded bed map of the Kongsfjord area. Velocity data of Kronebreen derived from feature tracking of high-res visible imagery is also combined with thickness data to calculate estimates of flux throughout the glacier. Analysis of this new data will give a better understanding of Kronebreen's retreat history, its mass balance and flux into Kongsfjord, and help in making predictions of when and how quickly further glacier retreat may occur.

O'Sadnick, M.; Kohler, J.; Langley, K.; Kehrl, L. M.; Berthier, E.

2010-12-01

104

The Cortical Topography of Local Sleep  

PubMed Central

In a recent series of experiments, we demonstrated that a visuomotor adaptation task, 12 hours of left arm immobilization, and rapid transcranial magnetic stimulation (rTMS) during waking can each induce local changes in the topography of electroencephalographic (EEG) slow wave activity (SWA) during subsequent non-rapid eye movement (NREM) sleep. However, the poor spatial resolution of EEG and the difficulty of relating scalp potentials to the activity of the underlying cortex limited the interpretation of these results. In order to better understand local cortical regulation of sleep, we used source modeling to show that plastic changes in specific cortical areas during waking produce correlated changes in SWA during sleep in those same areas. We found that implicit learning of a visuomotor adaptation task induced an increase in SWA in right premotor and sensorimotor cortices when compared to a motor control. These same areas have previously been shown to be selectively involved in the performance of this task. We also found that arm immobilization resulted in a decrease in SWA in sensorimotor cortex. Inducing cortical potentiation with repetitive transcranial magnetic stimulation (rTMS) caused an increase in SWA in the targeted area and a decrease in SWA in the contralateral cortex. Finally, we report the first evidence that these modulations in SWA may be related to the dynamics of individual slow waves. We conclude that there is a local, plasticity dependent component to sleep regulation and confirm previous inferences made from the scalp data. PMID:21906021

Murphy, Michael; Huber, Reto; Esser, Steve; Riedner, Brady A.; Massimini, Marcello; Ferrarelli, Fabio; Ghilardi, M. Felice; Tononi, Giulio

2011-01-01

105

The length-scaling properties of topography  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

106

Engineering microscale topographies to control the cell–substrate interface  

PubMed Central

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

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

2013-01-01

107

Linear and nonlinear stratified spindown over sloping topography  

E-print Network

In a stratified rotating fluid, frictionally driven circulations couple with the buoyancy field over sloping topography. Analytical and numerical methods are used to quantify the impact of this coupling on the vertical ...

Benthuysen, Jessica A

2010-01-01

108

Geoid height versus topography for oceanic plateaus and swells  

NASA Technical Reports Server (NTRS)

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.

Sandwell, David T.; Mackenzie, Kevin R.

1989-01-01

109

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

USGS Publications Warehouse

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.

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

110

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 ...

111

Stimulus control topography coherence theory: Foundations and extensions  

PubMed Central

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

McIlvane, William J.; Dube, William V.

2003-01-01

112

Functional topography: Multidimensional scaling and functional connectivity in the  

E-print Network

1 Functional topography: Multidimensional scaling and functional connectivity in the brain. Friston connectivity, Multidimensional scaling, Schizophrenia, PET, Singular Value Decomposition, Eigenimages, Spatial into an anatomical space, for example using statistical parametric mapping to identify activation foci

Gabrieli, John

113

Gravity driven shallow water models for arbitrary topography  

Microsoft Academic Search

We derive new models for gravity driven shallow water flows\\u000ain several space dimensions over a general topography.\\u000aA first model is valid for small slope variation, i.e. small curvature,\\u000aand a second model is valid for arbitrary topography.\\u000aIn both cases no particular assumption is made on the velocity profile in the material layer.\\u000aThe models are written for

Francois Bouchut; Michael Westdickenberg

2004-01-01

114

Spectral analysis of the gravity and topography of Mars  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

115

Evolution of Topography in Glaciated Mountain Ranges  

NASA Technical Reports Server (NTRS)

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

Brocklehurst, Simon H.

2002-01-01

116

Corneal topography from spectral optical coherence tomography (sOCT)  

PubMed Central

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

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

2011-01-01

117

Controls on (anomalous) topography in rifted margin settings  

NASA Astrophysics Data System (ADS)

Contrasting end members of volcanic and non-volcanic passive margin formation show a large variability in basin shape and structure, subsidence history, and associated topographic evolution of the onshore rifted margins. The large range of structural style and associated topography of these systems imply a strong variability in the underlying thermo-mechanical conditions at the time of rifting. Rift - passive margin styles ranging from narrow to ultra wide are explained using forward numerical models with varying rheological structure, with strong crust lithosphere leading to narrow rift formation associated with highly elevated rift shoulders and conversely weak crust lithosphere resulting in highly stretched wide rifted conjugate margins and little flank morphology. In some cases rifted margins appear to indicate the formation of anomalous post rift topography. A number of mechanisms including small-scale convective removal of the lower lithosphere, lithosphere counter-flow, and dynamic topography, have been invoked to explain the anomalous topography. Forward numerical models are used to predict the magnitude and characteristic topography associated with each of these mechanisms and to evaluate their potential for explaining these apparent anomalous characteristics of rifts and rifted margins.

Huismans, Ritske S.

2014-05-01

118

Linear baroclinic instability in the presence of large scale topography  

NASA Technical Reports Server (NTRS)

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.

Reynolds, Nathaniel Dunton

1987-01-01

119

Topography and functional information of plasma membrane.  

PubMed

By using atomic force microscope (AFM), the topography and function of the plasmalemma surface of the isolated protoplasts from winter wheat mesophyll cells were observed, and compared with dead protoplasts induced by dehydrating stress. The observational results revealed that the plasma membrane of living protoplasts was in a state of polarization. Lipid layers of different cells and membrane areas exhibited distinct active states. The surfaces of plasma membranes were unequal, and were characterized of regionalisation. In addition, lattice structures were visualized in some regions of the membrane surface. These typical structures were assumed to be lipid molecular complexes, which were measured to be 15.8+/-0.09 nm in diameter and 1.9+/-0.3 nm in height. Both two-dimensional and three-dimensional imaging showed that the plasmalemma surfaces of winter wheat protoplasts were covered with numerous protruding particles. In order to determine the chemical nature of the protruding particles, living protoplasts were treated by proteolytic enzyme. Under the effect of enzyme, large particles became relatively looser, resulting that their width was increased and their height decreased. The results demonstrated that these particles were likely to be of protein nature. These protein particles at plasmalemma surface were different in size and unequal in distribution. The diameter of large protein particles ranged from 200 to 440 nm, with a central micropore, and the apparent height of them was found to vary from 12 to 40 nm. The diameter of mid-sized protein particles was between 40-60 nm, and a range of 1.8-5 nm was given for the apparent height of them. As for small protein particles, obtained values were 12-40 nm for their diameter and 0.7-2.2 nm for height. Some invaginated pits were also observed at the plasma membrane. They were formed by the endocytosis of protoplast. Distribution density of them at plasmalemma was about 16 pits per 15 microm(2). According to their size, we classified the invaginated pits into two types--larger pits measuring 139 nm in diameter and 7.2 nm in depth, and smaller pits measuring 96 nm in diameter and 2.3 nm in depth. On dehydration-induced dead protoplasts, the degree of polarization of plasma membranes decreased. Lipid molecular layers appeared relatively smooth, and the quantity of integral proteins reduced a lot. Invaginated pits were still detectable at the membrane surface, but due to dehydration-induced protoplast contraction, the orifice diameter of pits reduced, and their depth increased. Larger pits averagely measuring 47.4 nm in diameter and 31.9 nm in depth, and smaller pits measuring 26.5 nm in diameter and 43 nm in depth at average. The measured thickness of plasma membranes of mesophyll cells from winter wheat examined by AFM was 6.6-9.8 nm, thicker in regions covered with proteins. PMID:18239886

Sun, DeLan; Chen, JianMin; Song, YanMei; Zhu, ChuanFeng; Pan, GeBo; Wan, LiJun

2008-02-01

120

Laser-based nanoengineering of surface topographies for biomedical applications  

NASA Astrophysics Data System (ADS)

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.

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

2011-04-01

121

Implications of MOLA Global Roughness, Statistics, and Topography  

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

122

Sintered silver joints via controlled topography of electronic packaging subcomponents  

SciTech Connect

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.

Wereszczak, Andrew A.

2014-09-02

123

Surface topography prediction on laser processed tool steel  

NASA Astrophysics Data System (ADS)

In laser surface treatment the laser beam is used as energy source for surface modification improving aspects such as mechanical properties, tribology or surface texture. Modeling tools have special interest in processes with many variables, like laser surface processing, in order to minimize the tryout testing to find the optimal process parameters. The work presented here focuses on the prediction of the final topography in laser polishing process. By FFT analysis of the surface profile it is possible to get the different frequency components of the initial topography. On the other hand, thermal field simulation was carried out to evaluate the melt duration. Matching this with the spatial frequency damping during process, the reconstruction of the processed topography was obtained.

Ukar, E.; Lamikiz, A.; Martínez, S.; López de Lacalle, L. N.

2012-04-01

124

Crystal quality analysis and improvement using x-ray topography.  

SciTech Connect

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

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

2008-01-01

125

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

PubMed

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 ?m) 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. PMID:24706140

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

2013-12-01

126

Effect of topography on sulfate redistribution in Cumulonimbus cloud development.  

PubMed

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

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

2014-03-01

127

Ulva linza zoospore sensitivity to systematic variation of surface topography  

NASA Astrophysics Data System (ADS)

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

Sheats, Julian Taylor

128

Rigid gas permeable contact lens and corneal topography.  

PubMed

We investigated the effect of high Dk daily wear rigid gas permeable contact lenses on corneal topography. Eight young myopic subjects wore hard contact lenses for 21 days. Corneal topography was monitored using the EyeSys system. It was measured every day during the next 21 days after the fitting. We recorded the corneal radius of curvature at 16 peripheral points approximately 1, 2, 3 and 4 mm along the four principal meridians (nasal, superior, inferior and temporal). Our study showed that daily wear RGP Forum 210 does not produce significant alterations of the corneal curvature as a function of time. PMID:11396397

Yebra-Pimentel, E; Giráldez, M J; Arias, F L; González, J; González, J M; Parafita, M A; Febrero, M

2001-05-01

129

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

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

130

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

NASA Technical Reports Server (NTRS)

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

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

2010-01-01

131

Topography of Small Coronae on Venus: Preliminary Overview  

NASA Astrophysics Data System (ADS)

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.

Kreslavsky, M.; Vdovichenko, R.

1996-03-01

132

Sound propagation over uneven ground and irregular topography  

NASA Technical Reports Server (NTRS)

The goal of this research is to develop theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere. Irregular topography 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.

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

1988-01-01

133

The Impact of Weather & Topography on Landslide Development  

NSDL National Science Digital Library

The Real World Learning Objects Resource Library has provided this activity to demonstrate the role of weather and topography in environmental disasters. Students will use real GIS data to analyze the relationship between weather, topography and landslides. Background materials and worksheets are provided in the âÂÂContent Materialsâ section, and the procedure for students to follow is clearly outlined. Additional materials that students may find helpful are located in the âÂÂSupplementary Resourcesâ section. This is an excellent resource for environmental science and earth science teachers that can be used in the classroom or as a homework assignment.

Kimbler, Frank

2008-02-01

134

Venus gravity and topography: 60th degree and order model  

NASA Technical Reports Server (NTRS)

We have combined the most recent Pioneer Venus Orbiter (PVO) and Magellan (MGN) data with the earlier 1978-1982 PVO data set to obtain a new 60th degree and order spherical harmonic gravity model and a 120th degree and order spherical harmonic topography model. Free-air gravity maps are shown over regions where the most marked improvement has been obtained (Ishtar-Terra, Alpha, Bell and Artemis). Gravity versus topography relationships are presented as correlations per degree and axes orientation.

Konopliv, A. S.; Borderies, N. J.; Chodas, P. W.; Christensen, E. J.; Sjogren, W. L.; Williams, B. G.; Balmino, G.; Barriot, J. P.

1993-01-01

135

Moire Topography For The Detection Of Orthopaedic Defects  

NASA Astrophysics Data System (ADS)

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

Kamal, Syed A.; Lindseth, Richard E.

1981-02-01

136

Bed topography and the development of forced bed surface patches  

E-print Network

2010; published 24 November 2010. [1] Channel topography in gravelbedded rivers interacts with the local flow and sediment transport fields to produce "forced patches," which are temporally stable areas in which a large (55 m long, 2.74 m wide), straight, sediment recirculating flume was provided a constant

Venditti, Jeremy G.

137

Methods for fabrication of nanoscale topography for tissue engineering scaffolds.  

PubMed

Observations of how controlling the microenvironment of cell cultures can lead to changes in a variety of parameters has lead investigators to begin studying how the nano-environment of a culture can affects cells. Cells have many structures at the nanoscale such as filipodia and cytoskeletal and membrane proteins that interact with the environment surrounding them. By using techniques that can control the nano-environment presented to a cell, investigators are beginning to be able to mimic the nanoscale topographical features presented to cells by extracellular matrix proteins such as collagen, which has precise and repeating nano-topography. The belief is that these nanoscale surface features are important to creating more natural cell growth and function. A number of techniques are currently being used to create nanoscale topographies for cell scaffolding. These techniques fall into two main categories: techniques that create ordered topographies and those that create unordered topographies. Electron Beam lithography and photo-lithography are two standard techniques for creating ordered features. Polymer demixing, phase separation, colloidal lithography and chemical etching are most typically used for creating unordered surface patterns. This review will give an overview of these techniques and cite observations from experiments carried out using them. PMID:16525765

Norman, James J; Desai, Tejal A

2006-01-01

138

Belonging: Cultural Topographies of Identity Dublin 8th-  

E-print Network

Belonging: Cultural Topographies of Identity Dublin 8th- 9th June 2012 Information for participants. Guests are free to make their own dinner arrangements on Thursday evening. Transport From Dublin airport to UCD/city: The (blue) aircoach runs frequent services from Dublin airport to the city

139

Examining topography and stream discharge at Sherburne National Wildlife Refuge  

NSDL National Science Digital Library

In this inquiry based geologic field lab students will be estimating and measuring stream flow. Students will also map out a full scale live topography map of a dry streambed to help them estimate flow discharge. Students will use their journals to record their hypothesis, lab report questions, graphed data and evidence to backs up their observations.

Todd Koenig Zimmerman High School ISD 728 Zimmerman, MN I will be using a modified concept of the contour mapping exercise we did at St. Thomas and the Hydrology flow lab we preformed at Coon Creek.

140

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

USGS Publications Warehouse

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.

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

141

Analysis of Multiple Manding Topographies during Functional Communication Training  

ERIC Educational Resources Information Center

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…

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

2009-01-01

142

Quantitative surface topography determination by Nomarski reflection microscopy I. Theory  

Microsoft Academic Search

The Nomarksi differential interference contrast microscope is examined as a tool for determination of metallic mirror surface topography. This discussion includes the development of an optical model for the Nomarski system, an examination of the key results of the model's application to sloped sample surfaces, and recommended procedures for implementation. The functional relationship is developed between image intensity and the

Delbert L. Lessor; John S. Hartman; Richard L. Gordon

1979-01-01

143

Mask topography effects in low k1 lithography  

NASA Astrophysics Data System (ADS)

With optical lithography driving device-manufacturing capability to subwavelength dimensions, complicated phenomena that were once safely ignored art playing a crucial role in determining process quality. One such critical effect result from the consideration of mask topography. As low k1 processes are entering pilot production, we as an industry are finding that we can no longer simply treat the mask as a simple planar surface and therefore consideration of reticle topography is becoming as important as pre-CMP wafer topography once was. The use of advanced masks in a low-k1 process is far from straightforward however, because any image model describing these processes must now predict the effects of light scatter from the mask that lead to a loss in already low process tolerance we have. In this paper we will discuss the extraction of mask topography information, using advanced atomic force microscopy (AFM), and the resultant structures simulated through the use of electro-magnetic field simulation. We will also verify the accuracy of these simulations by examining the correlation between data gathered on an Aerial Image Measurement System and the simulations. We will further show how we have transferred these EMF simulated masks to a conventional lithography simulator to estimate the effects in the resultant photoresist image. This data will be compared to the actual performance of the masks when exposed using state-of-the-art processing.

McCallum, Martin; Gordon, Ronald L.

2000-07-01

144

SLOPE DISTRIBUTIONS, THRESHOLD HILLSLOPES, AND STEADY-STATE TOPOGRAPHY  

E-print Network

SLOPE DISTRIBUTIONS, THRESHOLD HILLSLOPES, AND STEADY-STATE TOPOGRAPHY DAVID R. MONTGOMERY, and Fullsack, 1993; Howard, Dietrich, and Seidl, 1994; Montgomery, 1994; Tucker and Slingerland, 1994; Kirkby, 1997; Whipple, Kirby, and Brocklehurst, 1999; Whipple and Tucker, 1999). Such efforts have spawned

Montgomery, David R.

145

Ultrastructural basement membrane topography of the bladder epithelium  

Microsoft Academic Search

The basement membrane underlies epithelium and separates it from deeper tissues. Recent studies suggest that nanoscale topography of the surface of basement membrane may modulate adhesion, migration, proliferation and differentiation of overlying epithelium. This study was performed to elucidate nanoscale topographic features of basement membrane of the bladder. Bladder tissues were obtained from three adult female rhesus macaques. A process

George A. Abrams; Christopher J. Murphy; Zun-Yi Wang; Paul F. Nealey; Dale E. Bjorling

2003-01-01

146

Short wavelength topography on the inner-core boundary  

PubMed Central

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

Cao, Aimin; Masson, Yder; Romanowicz, Barbara

2007-01-01

147

The Shuttle Radar Topography Mission: Introduction to Special Session  

Microsoft Academic Search

The Shuttle Radar Topography Mission (SRTM), which flew successfully aboard Endeavour in February 2000, is a cooperative project between NASA, the National Imagery and Mapping Agency, and the German and Italian Space Agencies. The mission was designed to use a single-pass radar interferometer to produce a digital elevation model of the Earth's land surface between about 60^o north and 56^o

T. G. Farr; M. Werner; M. Kobrick

2003-01-01

148

EAARL topography-Potato Creek watershed, Georgia, 2010  

USGS Publications Warehouse

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.

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

2011-01-01

149

Neural Networks Applied to Estimating Subglacial Topography and Glacier Volume  

Microsoft Academic Search

To predict the rate and consequences of shrinkage of the earth's mountain glaciers and ice caps, it is necessary to have improved regional-scale models of mountain glaciation and better knowledge of the subglacial topography upon which these models must operate. The problem of estimating glacier ice thickness is addressed by developing an artificial neural network (ANN) approach that uses calculations

Garry K. C. Clarke; Etienne Berthier; Christian G. Schoof; Alexander H. Jarosch

2009-01-01

150

Surface Topography Quantification by Integral and Feature-related Parameters  

E-print Network

microscopy, the topography of brittle fracture surfaces and wire- eroded surfaces was quantified. The global brittle fracture surfaces of steel. Key words: algorithm, CLSM, fracture surface, topometry Die. The latter describe discrete geometrical objects, for example, planar regions like fracture facets in brittle

Smid, Michiel

151

GMT: Texas/El Paso Topography Lab 9 Part 3  

E-print Network

-window startup · PCs: If you need to, launch Cygwin, then in the black window, type: startxwin.bat. Use the white a topography map (see next pages). #12;Modify psbasemap command ·First you will modify the psbasemap command this, list your files by typing the following in your X-window: ! ! $ ls! (you should see the files

Smith-Konter, Bridget

152

Ammonia synthesis  

Microsoft Academic Search

In a process for producing ammonia in a synthesis loop in which fresh synthesis gas containing hydrogen, nitrogen and, lesser amounts of argon and methane is combined with a hydrogen enriched recycle gas to provide combined synthesis gas, the combined synthesis is introduced to and reacted over ammonia synthesis catalyst under synthesis conditions to provide converted gas containing ammonia, hydrogen,

B. G. Mandelik; J. R. Cassata; P. J. S. Katy; C. P. Van Dijk

1986-01-01

153

The effects of abrupt topography on plankton dynamics.  

PubMed

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

Zavala Sansón, L; Provenzale, A

2009-12-01

154

Influence of lunar topography on simulated surface temperature  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

155

Chloride channels and the reactions of cells to topography.  

PubMed

The reactions of rat epitenon cells to substratum topography on the micrometric and nanometric scale such as groove-ridge structures include cell extension, elongation and orientation reactions. In this paper we report that stretch-sensitive chloride channels may be involved in the earliest stages of these reactions in epitenon fibroblast-like cells. We report that rat epitenon-cells can develop appreciable lateral mechanical tension that could stretch both the force generating cells themselves and those nearby. We show that cells in medium in which more than 80% of the chloride has been replaced by nitrate show little reaction to topography. Spreading of the cells takes place but is much reduced along the direction of the groove-ridge topography but enhanced across the topography. The chloride channel inhibitors NPPB (5-Nitro-2- (3phenylpropylamino) benzoicacid) 4,4'-disothiocyanostilbene-2, 2' sulphonic acid (DIDS) and Chlorotoxin produce similar results which are further accentuated when these inhibitors are presented in low chloride medium. An antibody against ClC3, which has close homology to ClC5/6 also, blocked reaction to topography. These treatments have no significant effect on cell spreading on planar surfaces nor do they lead to changes in internal pH in the cells. There is a slight inhibition of rates of cell movement. Experiments using antisense oligoribonucleotides to ClC-5 or ClC-6 channel m-RNA also inhibit topographic reactions, which provides further confirmation of the hypothesis. Since the ClC-3,4 and 5 share considerable sequence similarities in the genes and in their proteins it has not been possible to make an unambigous determination of which precise chloride channel(s) is (are) involved. PMID:14562255

Tobasnick, G; Curtis, A S

2001-12-13

156

Seismic waveform inversion for core-mantle boundary topography  

NASA Astrophysics Data System (ADS)

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

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

2014-07-01

157

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

158

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

E-print Network

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

Nikurashin, Maxim (Maxim Anatolevich)

2009-01-01

159

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

E-print Network

The dynamics of the Mississippi River plume: Impact of topography, wind and offshore forcing), The dynamics of the Mississippi River plume: Impact of topography, wind and offshore forcing on the fate of topography, winddriven and eddydriven circulation on the offshore removal of plume waters. A realistically

Miami, University of

160

The Direct Breaking of Internal Waves at Steep1 Topography2  

E-print Network

1 The Direct Breaking of Internal Waves at Steep1 Topography2 Jody M. Klymak, Sonya Legg, Matthew H. Alford, Maarten Buijsman,3 Robert Pinkel and Jonathan D. Nash4 5 Abstract6 7 Internal waves are often steep "supercritical" topography (i.e. topography that is steeper than internal wave energy13

Klymak, Jody M.

161

A comprehensive characterization of 3D surface topography induced by hard turning versus grinding  

Microsoft Academic Search

Surface topography induced by precision machining is critical for component performance. Four representative surface topographies of turned and ground surfaces were prepared at “extreme” machining conditions (gentle and abusive) and compared in terms of 3-dimensional (3D) surface features of amplitude, area and volume, spatial, and hybrid parameters. The 3D surface topography maps revealed the anisotropic and repeatable nature of a

R. A. Waikar; Y. B. Guo

2008-01-01

162

Effects of dynamic topography on Australian Paleogeography in the Cenozoic  

NASA Astrophysics Data System (ADS)

We have investigated the effects of dynamic topography combined with eustatic sea level variations on Australian paleogeography for the Late Cretaceous to present. Using an analytical flow model (Steinberger et al., 2001, doi: 10.1016/S0012-821X(01)00229-1 with the surface plate velocity field as boundary condition, we advect density anomalies converted from tomographic velocity anomalies (SMEAN tomographic model; Becker &Boschi, 2002, doi: 10.1029/2001GC000168) back through time. For each time step, we compute dynamic topography with a free upper boundary. This approach allows us to evaluate the spatio-temporal effects of large scale mantle convection patterns on surface processes like continental flooding and sediment deposition. The Australian continent, especially the southern Australian margin, provides a unique example for an extensive region that has been stable and fairly isolated from plate boundary processes like flexure or rift shoulder uplift for the time between 70 Ma to the present. This makes it ideal to investigate the effects of dynamic topography. Late Cretaceous and Cenozoic sedimentary deposits along the southern Australian margin indicate transgressive/regressive phases of limited extent, which can not be explained by eustatic sea level fluctuations alone. By using common estimates for the eustatic sea level in conjunction with our dynamic topography model, we have been able to reconstruct the position of the Australian paleo-shorelines, flooding patterns and water depths. We find a good agreement of our computed paleogeography with published stratigraphic data for Tertiary brown coal deposits along the southern Australian seabord (Gippsland, Murray, Otway and Bremer Basins) and stratigraphic sequences in the Murray Basin region, along the NW Australian margin and in the Eromanga Basin. Despite minor spatial discrepancies between the current model output and geological data which yet remain unresolved, our approach and modular workflow set up provides an important stepping stone to understand the influence of deep Earth processes and their impact on sediment deposition and other geomorphological processes. Due to the usage of non-proprietary data formats and open-source software it is possible to easily change the dynamic topography model input and extend the computations to incorporate the effects of sedimentation history and isostasy. We expect a further convergence of predicted paleogeography from dynamic topography models with increasing accuracy and resolution of tomographic models.

Heine, C.; M{Ü}Ller, R.; Steinberger, B.

2006-12-01

163

Spatial and Temporal variability in Dynamic Topography in East Antarctica  

NASA Astrophysics Data System (ADS)

Recent aerogeophysical exploration has provided novel views of the Gamburtsev Subglacial Mountains and the Wilkes and Aurora subglacial basins in East Antarctica. Reconstructing the evolution of East Antarctic topography through time is a critical next step for developing new coupled climate and ice sheet models (e.g. http://www.antscape.org/). Insights into tectonic and isostatic components driving the uplift of the Gamburtsevs have emerged from geophysical investigations and modeling (Ferraccioli et al., 2011, Nature). However, our knowledge of the larger-scale consequences of dynamic topography in East Antarctica remains poor compared to other continents. Seismic tomographic models provide a tool to derive large-scale models of convection in the Earth's mantle, which can then be used to reconstruct dynamic topography through time. By analyzing grids of global dynamic topography from present-day to 100 Ma based on the tomographic models S40RTS & S20RTS (Ritsema et al. 1999, 2011) we assess for the first time the potential space-time variability in dynamic topography in East Antarctica. We acknowledge that there are significant limitations when compared to similar studies over other continents, such as the relatively poor seismic resolution of the lithosphere and asthenosphere beneath East Antarctica and the lack of geological and geophysical data to constrain surface movements through time. However, currently available global datasets do reveal several new insights. Our models reveal that at ca 65 Ma the Gamburtsev Province and Dronning Maud Land regions were elevated. This was followed by at least 500 m of subsidence throughout the Cenozoic. The increased regional elevation likely facilitated ephemeral ice cap development in the early Cenozoic, which was followed by ice cap coalescence to form the East Antarctic Ice Sheet at ca 34 Ma. In contrast, a major and more rapid increase in elevation (up to 1,000 m) is observed over the Transantarctic Mountains (TAM) and the adjacent Wilkes Subglacial Basin, in particular over the last 15 Ma. Neogene dynamic topography in the TAM region may be related to the flow of warm mantle from the West Antarctic Rift System and/or the Balleny plume.

Anderson, L.; Ferraccioli, F.; Eagles, G.; Steinberger, B.; Ritsema, J.

2012-04-01

164

Basal Topography of the South Polar Layered Deposits  

NASA Astrophysics Data System (ADS)

The ice inferred to comprise the south polar layered deposits (SPLD) represents a significant fraction of the total water reservoir of the planet. The basal topography of these deposits is currently unconstrained but may be expected to contain considerable relief based on the heavily cratered nature of the surrounding terrain. In this work we report on our efforts to characterize the overall nature of this basal topography and in so doing better constrain the volume of this important volatile reservoir. Our approach has been to measure elevations at the periphery of the SPLD (defined by [1]) and use various interpolation techniques to estimate the basal topography. We used 1300 control points from the edges and areas surrounding the SPLD and included extensive control points from within the Chasmae and other features to fit a surface beneath the SPLD. No assumptions were made about any lithospheric flexure, nor did the results suggest that possibility. We first tested a variety of surface interpolation routines on a comparable area of cratered terrain immediately adjacent to the SPLD, using the same spatial distribution of 1300 height control points as we used for the SPLD itself, and found that the topography was broadly reproducible (ignoring craters) to within a few hundred meters. The SPLD basal topography we derive can be subtracted from the current spatial topography to produce isopach maps of the layered deposits. All interpolation methods we tested (within the ArcMap 8.3) indicate a lower total SPLD volume than that previous published [Smith et al., 2001]. Our best estimate for the SPLD volume is ~1 million km3, with a formal error in volume of ~5%, corresponding to an average thickness of ~950 meters. In comparison, [2] estimated this volume to be ~1.2-1.7 million km3. The Prometheus impact basin is present as a rimmed depression, consistent with the inference by [3]. More unexpected is the presence of a broad ridge underlying nearly the entire eastern half of the SPLD, which makes those deposits relatively thin. Our isopach maps show the northwestern portion of the Ultimi lobe to be an isolated thick region, in agreement with [1]. [1] Kolb, E. J., and K. L. Tanaka (2001), Icarus, 154, 22-39. [2] Smith, D. E., et al. (2001), J. Geophys. Res., 106(E10), 23,689-23,722. [3] Byrne, S., and A. B. Ivanov (2004), J. Geophys. Res., In press.

Davies, C. W.; Murray, B. C.; Byrne, S.

2004-12-01

165

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

166

Venusian highlands - Geoid to topography ratios and their implications  

NASA Technical Reports Server (NTRS)

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.

Smrekar, Suzanne E.; Phillips, Roger J.

1991-01-01

167

Topography and refractometry of nanostructures using spatial light interference microscopy.  

PubMed

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

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

2010-01-15

168

Craters on Mars: Global Geometric Properties from Gridded MOLA Topography  

NASA Technical Reports Server (NTRS)

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.

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

2003-01-01

169

Sound propagation over uneven ground and irregular topography  

NASA Technical Reports Server (NTRS)

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

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

1987-01-01

170

Irregular topography at the Earth’s inner core boundary  

PubMed Central

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

Dai, Zhiyang; Wang, Wei; Wen, Lianxing

2012-01-01

171

Topography, relief, climate and glaciers: a global prespective  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

172

Functional analysis of separate topographies of aberrant behavior.  

PubMed Central

We conducted a functional analysis of distinct topographies of aberrant behavior displayed by 4 clients. We first analyzed the behaviors in an aggregate fashion and then separated the behaviors to formulate hypotheses about the maintaining variables for each behavior. The procedures were used in a two-phase experiment. During Phase 1, two extended functional analyses were completed, one in an inpatient unit and one in a special education classroom. During Phase 2, two brief functional analyses were completed in an outpatient clinic. Results indicated that hypotheses of separate functions for distinct behaviors can be generated using both extended and brief functional analyses when the results are graphed in the aggregate and are separated by response topography. The results also suggest that these methods can improve the accuracy of data interpretation and treatment selection. PMID:8063625

Derby, K M; Wacker, D P; Peck, S; Sasso, G; DeRaad, A; Berg, W; Asmus, J; Ulrich, S

1994-01-01

173

Comparison of roentgenography and moiré topography for quantifying spinal curvature.  

PubMed

The purpose of this study was to compare roentgenography and moiré topography for identification, treatment, and prevention of scoliosis at an early age. Moiré topography was used as an assessment tool for the quantitative examination of 12 children with mild-to-moderate scoliosis receiving physical therapy during a three-month period. Each child's roentgenogram also was analyzed independently by orthopedic physicians and radiologists using the Cobb method of measuring spinal curvature. Rho correlations of Cobb angles and the spinal curvature angles based on moiré photographs taken at weeks 4, 8, and 12 were found to be +.94, +.96, and +.93, respectively. The moiré method, thus, may be used as an available, inexpensive, and easily interpreted diagnostic and treatment tool in physical therapy. PMID:3725893

el-Sayyad, M M

1986-07-01

174

Stresses in a submarine topography under ocean waves  

SciTech Connect

The problem of submarine slope stability is of interest to both offshore engineering and geology. In an uneven topography, the weight above a horizontal plane induces two-dimensional variation in the static stress field. The action of wave pressure, which changes with depth, further introduces excess pore pressure and dynamic stresses in the sea bottom. In the present paper, we combine a simple analytical theory for the static stress by the present authors, and the recent solution by Mei and Foda for wave-induced stresses in a plane poro-elastic sea bed to account for mild bottom slope and wave shoaling, to obtain the effective stress field in a submarine topography under sea waves. Sample results are given for a ridge and a canyon. In particular the dynamic pore pressure and the combined static and dynamic effective stresses are presented. 10 references, 11 figures.

Mei, C.C.; McTigue, D.F.

1984-01-01

175

Stresses in a submarine topography under ocean waves  

SciTech Connect

The problem of submarine slope stability is of interest to both offshore engineering and geology. In an uneven topography, the weight above a horizontal plane induces two-dimensional variation in the static stress field. The action of wave pressure, which changes with depth, further introduces excess pore pressure and dynamic stresses in the sea bottom. In the present paper, we combine a simple analytical theory for the static stress by the present authors, and the recent solution by Mei and Foda for wave-induced stresses in a plane poro-elastic sea bed to account for mild bottom slope and wave shoaling, and obtain the effective stress field in a submarine topography under sea waves. Sample results are given for a ridge and a canyon. In particular, the dynamic pore pressure and the combined static and dynamic effective stresses are presented.

Mei, C.C.; McTigue, D.F.

1984-09-01

176

Method and Apparatus for Creating a Topography at a Surface  

DOEpatents

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.

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

2008-11-11

177

The long wavelength topography of Beethoven and Tolstoj basins, Mercury  

NASA Astrophysics Data System (ADS)

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

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

2005-11-01

178

Evaluating Marie Byrd Land stability using an improved basal topography  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

179

Two Notions Contrasted: 'Logical Geography' and 'Logical Topography'  

E-print Network

by Gilbert Ryle: The logical topography of 'Logical Geography'. Aaron Sloman This file is http://www.cs.bham.ac.uk/research/projects/cogaff/misc/logical-geography.html Also available as messy, automatically generated PDF file http://www.cs.bham.ac.uk/research/projects: added Portia spider example. Updated: 21 Apr 2008 Update: 8 Jan 2008 On re-reading Appendices III and IV

Sloman, Aaron

180

Correcting for surface topography in X-ray fluorescence imaging.  

PubMed

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

Geil, E C; Thorne, R E

2014-11-01

181

ATM Coastal Topography-Florida 2001: Eastern Panhandle  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the eastern Florida panhandle coastline, acquired October 2, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or first surface topography.

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

2009-01-01

182

ATM Coastal Topography-Texas, 2001: UTM Zone 14  

USGS Publications Warehouse

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

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

2009-01-01

183

Towards Mapping the Ocean Surface Topography at 1 km Resolution  

NASA Technical Reports Server (NTRS)

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.

Fu, Lee-Lueng; Rodriquez, Ernesto

2006-01-01

184

ATM Coastal Topography-Florida 2001: Western Panhandle  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the western Florida panhandle coastline, acquired October 2-4 and 7-10, 2001. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative scanning Lidar instrument originally developed by NASA, and known as the Airborne Topographic Mapper (ATM), was used during data acquisition. The ATM system is a scanning Lidar system that measures high-resolution topography of the land surface and incorporates a green-wavelength laser operating at pulse rates of 2 to 10 kilohertz. Measurements from the laser-ranging device are coupled with data acquired from inertial navigation system (INS) attitude sensors and differentially corrected global positioning system (GPS) receivers to measure topography of the surface at accuracies of +/-15 centimeters. The nominal ATM platform is a Twin Otter or P-3 Orion aircraft, but the instrument may be deployed on a range of light aircraft. Elevation measurements were collected over the survey area using the ATM system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or first surface topography.

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

2009-01-01

185

ATM Coastal Topography-Texas, 2001: UTM Zone 15  

USGS Publications Warehouse

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

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

2009-01-01

186

Shuttle radar topography mission produces a wealth of data  

Microsoft Academic Search

On February 22, 2000, the Space Shuttle Endeavour landed at Kennedy Space Center, completing the highly successful 11-day flight of the Shuttle Radar Topography Mission (SRTM). Onboard were over 300 high-density tapes containing data for the highest resolution digital topographic map of Earth ever made.SRTM is a cooperative project between the National Aeronautics and Space Administration (NASA) and the National

Tom G. Farr; Mike Kobrick

2000-01-01

187

Electronic cigarettes: abuse liability, topography and subjective effects  

PubMed Central

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

Evans, Sarah E; Hoffman, Allison C

2014-01-01

188

The development of surface topography using two ion beams  

Microsoft Academic Search

Ion etching is a well-established technique for the micromachining of solid surfaces. It is used extensively in surface analysis with techniques such as Auger electron spectroscopy, ESCA and SIMS, both for surface cleaning and composition—depth profiling. In all of these applications the formation of ion-induced surface topography is a serious problem. Experimental evidence has shown that the use of two

S. S. Makh; R. Smith; J. M. Walls

1982-01-01

189

Ocean surface topography from space (TOPEX/Poseidon Missions)  

NSDL National Science Digital Library

Joint US and France project, the TOPEX-Poseidon satellites continuously measures sea surface height. Oceans store and transport solar heat, helping to keep Earth's climate in balance. The overall shape of the oceans' "hills" and "valleys" is called ocean surface topography, or OST. Precise knowledge of OST is essential to predict the effects of catastrophic storms. Educational resources available for all ages and backgrounds. Outstanding animation of OTS also included.

190

The submerged offshore breakwater and its effects on seafloor topography  

E-print Network

/B for the emergent offshore breakwater. It has been postulated that tombolo formation cannot occur in the case of the submerged offshore breakwater. However, the spit-growth/relative d1stance from shore relationship is expected to be similar. The beach...THE SUBMERGED OFFSHORE BREAKWATER AND ITS EFFECTS ON SEAFLOOR TOPOGRAPHY A Thesis by JAMES RUSSELL TALLENT Submitted to the Graduate College of Texas AGM University in partial fulfillment of the requirements for the degree of MASTER...

Tallent, James Russell

2012-06-07

191

Biocompatibility of TiO2 nanotubes with different topographies.  

PubMed

The biological response of osteoblast cells to implant materials depends on the topography and physico-chemistry of the implant surface and this determines the cell behavior such as shaping, adhesion and proliferation, and finally the cell fate. In this study, titanium (Ti) was anodized to create different topographies of titania nanotubes (TNTs) to investigate the cell behavior to them. TNTs with and without a highly ordered nanoporous layer on their top surface were fabricated using two-step and one-step anodizing processes, respectively. The TNTs without a highly ordered nanoporous layer on the top surface exhibited a rougher surface, higher surface energy and better hydrophilicity than the TNTs with such a layer. Osteoblast-like cells (SaOS2) were used to assess the biocompatibility of the TNTs with different topographies in comparison to bare cp-Ti. Results indicated that TNTs can enhance the proliferation and adhesion of osteoblast-like cells. TNTs without a highly ordered nanoporous layer exhibited better biocompatibility than the TNTs covered by such a nanoporous layer. Cell morphology observation using confocal microscopy and SEM indicated that SaOS2 cells that were adhered to the TNTs without the highly ordered nanoporous layer showed the longest filopodia compared to TNTs with a highly ordered nanoporous layer and bare cp-Ti. PMID:23554372

Wang, Yu; Wen, Cuie; Hodgson, Peter; Li, Yuncang

2014-03-01

192

Anomalous topography on the continental shelf around Hudson Canyon  

USGS Publications Warehouse

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

Knebel, H. J.

1979-01-01

193

EAARL Topography-Sagamore Hill National Historic Site  

USGS Publications Warehouse

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.

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

2007-01-01

194

Solitary wave dynamics in shallow water over periodic topography.  

PubMed

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

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

2005-09-01

195

Age and Prematurity of the Alps Derived from Topography  

NASA Astrophysics Data System (ADS)

The European Alps are one of the best studied mountain ranges on Earth, but yet the age of their topography is almost unknown. Even their relative stage of evolution is unclear: Are the Alps still growing, in a steady state or already decaying, and is there a significant difference between Western and Eastern Alps? Using a new geomorphic parameter we analyze the topography of the Alps and provide one of the first quantitative constraints demonstrating that the range is still in its infancy: In contrast to several other mountain ranges, the Alps have still more than half of their evolution to a geomorphic steady state to go. Combining our results with sediment budget data from the surrounding basins we infer that the formation of the present topography began only 5-6 million years ago. Our results question the apparent consensus that the topographic evolution is distributed over much of the Miocene and might give new impulses to the reconstruction of paleoclimate in Central Europe.

Hergarten, S.; Wagner, T.; Stüwe, K.

2010-09-01

196

Puffing Topography and Nicotine Intake of Electronic Cigarette Users  

PubMed Central

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

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

2015-01-01

197

Global snowline and mountain topography: a contrasted view  

NASA Astrophysics Data System (ADS)

The examination of the relationship between Earth's topography and present and past climate (i.e., long-term elevation of glaciers Equilibrium Line Altitude) reveals that the elevation of mountain ranges may be limited or controlled by glaciations (e.g. Porter, 1989). This is of prime importance, because glacial condition would lead to a limit the mountain development, hence the accumulation of gravitational energy and prevent the development of further glacial conditions as well as setting the erosion in (peri)glacial environments. In this study, we examine the relationships between topography and the global Equilibrium Line Altitude of alpine glaciers around the world (~ long term snowline, i.e. the altitude where the ice mass balance is null). This analysis reinforce a global study previously published (Champagnac et al., 2012), and provide a much finer view of the climate-topography-tectonics relationships. Specifically, two main observations can be drawn: 1) The distance between the (averaged and maximum) topography, and the ELA decreases pole ward the poles, and even become reversed (mean elevation above to ELA) at high latitude. Correlatively, the elevation of very large portion of land at mid-latitude cannot be related to glaciations, simply because it was never glaciated (large distance between topography and long-term mean ELA). The maximum distance between the ELA and the topography is greater close to the equator and decreases poleward. In absence of glacial and periglacial erosion, this trend cannot have its origin in glacial and periglacial processes. Moreover, the ELA elevation shows a significant (1000~1500m) depression in the intertropical zone. This depression of the ELA is not reflected at all in the topography 2) The distribution of relief on Earth, if normalized by the mean elevation of mountain ranges (as a proxy for available space to create relief, see Champagnac et al., 2012 for details) shows a latitudinal band of greater relief between ~40 and ~60° (or between ELA of ~500m to ~2500m a.s.l.). This mid-latitude relatively greater relief challenges the straightforward relationship between glaciations, erosion and topography. Oppositely, it suggests that glacier may be more efficient agent in temperate area, with an important amplitude between glacial and interglacial climate. This is consistent with the view of a very variable glacier erodibility that can erode and protect the landscape, as well as with studies documenting a bimodal location of the preferred glacial erosion, at relatively high elevation (around the long-term ELA), and at much lower elevation (close to the glacial maximum lower reaches), thanks to efficient water lubrication of the glacier bases that greatly enhance the sliding velocity (Herman et al., 2011). These findings show that the relation between the mountain topography and the long term snowline is not as straightforward as previously proposed (e.g. Egholm et al., 2009) . Beside the role of tectonic forcing highlighted by several authors (e.g. Pedersen et al., 2010;Spotila and Berger, 2010),, the importance of the glacial erosion appears to be crucial at mid latitude, but more complex at both high and low latitude. Moreover, the relief at mid latitude appears to be higher, hence suggesting a positive correlation between relief and topographic control of glacier on the landscape Champagnac, J.-D., Molnar, P., Sue, C., and Herman, F.: Tectonics, Climate, and Mountain Topography, Journal of Geophysical Research B: Solid Earth, 117, doi:10.1029/2011JB008348, 2012. Egholm, D. L., Nielsen, S. B., Pedersen, V. K., and Lesemann, J. E.: Glacial effects limiting mountain height, Nature, 460, 884-888, 2009. Herman, F., Beaud, F., Champagnac, J.-D., Lemieux, J.-M., and Sternai, P.: Glacial hydrology and erosion patterns: A mechanism for carving glacial valleys, Earth and Planetary Science Letters, 310, 498-508, 2011. Pedersen, V. K., Egholm, D. L., and Nielsen, S. B.: Alpine glacial topography and the rate of rock column uplift: a global perspective, Geomorphology, 122, 129-139, 10.1

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

2013-04-01

198

Open questions in surface topography measurement: a roadmap  

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

199

Crater topography on Titan: Implications for landscape evolution  

NASA Astrophysics Data System (ADS)

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 craters on Titan (gray diamonds) compared to similarly sized, fresh craters on Ganymede (central peaks, +; central pits, *) and a handful of relaxed craters (black squares) from Bray et al. (2012). References: Bray, V., et al.: "Ganymede crater dimensions - implications for central peak and central pit formation and development". Icarus, Vol. 217, pp. 115-129, 2012. Neish, C.D., Lorenz, R.D.: "Titan’s global crater population: A new assessment". Planetary and Space Science, Vol. 60, pp. 26-33, 2012. Schenk, P.M., et al.: "Ages and interiors: the cratering record of the Galilean satellites". In: Bagenal, F., McKinnon, W.B. (Eds.), Jupiter: The Planet, Satellites, and Magnetosphere, Cambridge University Press, Cambridge, UK, pp. 427-456, 2004. Stiles, B.W., et al.: "Determining Titan surface topography from Cassini SAR data". Icarus, Vol. 202, pp. 584-598, 2009. Wood, C.A., et al.: "Impact craters on Titan". Icarus, Vol. 206, pp. 334-344, 2010.

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

2012-04-01

200

Reconstructed Paleo-topography of the Columbia Hills, Mars  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

201

Analysis on 3d Topography Effects on Magnetotelluric Responses  

NASA Astrophysics Data System (ADS)

Magnetotelluric (MT) surveys based on a natural electromagnetic induction in the Earth have been conducted to investigate geothermal resources in Pohang, Jeju Island, and Seokmo Island, Korea. Although some of the MT surveys indicated fracture systems through which relatively high-temperature fluid flows, the temperature is still not enough for a traditional geothermal power plant. However, even when natural convective hydrothermal resources are unavailable, an enhanced geothermal system (EGS), a new type of geothermal power technologies, can produce heat and electricity by harnessing the energy from hot rock at depths ranging from about 3 km to 10 km. This fact makes EGS a hot issue in Korea for geothermal power plant, even though EGS not only has lower capacity of power generation than the traditional one but also more expensive. As a starting stage of site characterization for EGS, which will be followed by temperature and stress estimation, precise interpretation of MT data distorted by irregular surface terrain is critical in Korea, since almost 70% of the land of Korea is mountainous terrain. This study investigates topography effects on MT responses, i.e., apparent resistivities, phases, tippers and induction vectors for a three-dimensional (3D) hill model. To calculate MT responses for a model with surface topography, we use a 3D MT modeling algorithm based on an edge finite-element method. Numerical experiments indicate that current distortion by surface topography affects MT responses such as apparent resistivites, phases, and tippers. Apparent resistivities in the xy mode are slightly higher than the background resistivity near hill slopes in the x-direction while the resistivities are smaller over the hill. Distortions on amplitudes of tippers over a hill are quite similar to those over a valley. The directions of tippers over a hill are toward the summit of the hill, while those over a valley are toward the base.

Nam, M.; Han, N.; Kim, H.; Song, Y.

2010-12-01

202

Topography and biological noise determine acoustic detectability on coral reefs  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

203

Management intensity and topography determined plant diversity in vineyards.  

PubMed

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 maintaining and improving wild plant diversity. PMID:24098435

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

2013-01-01

204

Topography of the Central Andes: Effects from Above and Below  

NASA Astrophysics Data System (ADS)

The topography of the central Andes is the product of an interaction between solid earth and atmospheric processes -- tectonic processes tend to build topography and climatic ones erode and redistribute it. Here we can assess the relative significance of these effects because tectonic and climate patterns have very different spatial characteristics relative to the high plateau. The stable Nazca-South America plate motions of the mid-Tertiary to present, and the consequent dynamics of the modern Andes, have a high degree of spatial order -- principally a bilateral symmetry on a vertical-ENE trending plane across the plateau, parallel to particle motions of both plates. This pattern is strongly violated by climate -- wet in the north on the east side of the plateau, and dry in the south -- and consequent erosion. To resolve these effects on the topography, we consider vertical profiles across the mountain belt and subduction zone. Parallel sections equidistant from but on opposite sides of the symmetry plane experience similar kinematics but different climate effects. Although precipitation amounts vary considerably north to south along the eastern edge of the plateau, the topography there is very similar on both sides of the symmetry plane. On the other hand, the geometry of the subducted Nazca plate varies north to south, though the plate kinematics do not vary. These and other observations suggest that the overriding and subducting plates are partially coupled by viscous stresses across a narrow asthenospheric wedge, such that the mountain belt and subduction zone dynamically respond to variations in loading at the earth's surface (caused by erosion in the north versus the lack thereof in the south). Both the South America and Nazca plates deform as they slide past one another nearly face-to-face across the asthenospheric wedge. The incremental deformation of the overriding plate is probably less than that of the subducting plate; however, the former is stationary and accumulates deformation (to build the plateau) while the latter is constantly refreshed. Indeed the upper plate must be relatively strong (i.e., resists deformation) and the mantle beneath deforms owing to drag on its stable upper surface to accomodate the flow induced by subduction. Thus, minor climate effects, causing uneven erosion of the plateau, may affect the geometry and motion of the subducted slab.

Gephart, J. W.

2003-12-01

205

X-ray topography study of complex silicon microcircuits  

NASA Technical Reports Server (NTRS)

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

Parker, D. L.

1981-01-01

206

The CMB Topography Beneath Cook Inlet And Alaskan Kenai Peninsula  

NASA Astrophysics Data System (ADS)

It has long been known that the PcP-to-P amplitude ratios demonstrate strong scatter in some regions. Rost and Revenaugh studied PcP amplitudes which sample the core-mantle boundary (CMB) beneath the Alaskan Kenai peninsula and the Cook inlet and found a ˜1° region on the CMB with very large PcP/P amplitude ratios. For some events, the ratios are several tens times larger than the theoretical ratios. After analyzing different possible mechanisms, they concluded the CMB topography is the major cause of the high amplitude ratios, but they did not give an quantitative topography model because of the lack of short period synthetic waveforms tools. We generate short period PcP synthetics using representation theorems and study the PcP phases theoretically for a core-mantle boundary (CMB) with single sinusoidal topography. After testing different combinations of the sinusoid wavelength L and amplitude H, we conclude that a dent in CMB with diameter of L=300km and height H=1˜2km best fits the observed data and can partly explain the high amplitude ratios. The PcP reflected from the CMB dip with L=300km and H=2km will be amplified by 2˜3 times which is smaller than the value the observed data needed. We primarily have three causes to determine L=300km and H=1˜2km. First, a dip with L=300km and H=1˜2km will focus the PcP significantly in a ˜1° region on the CMB which is consistent with the observed data. Certainly, the northern limit of the region is not clear, therefore more data are needed to constraint the northern limit and give a more reliable model. Second, there are not obvious travel time anomalies coupled with the high ratios in the observed PcP and our synthetic travel time anomalies are just about 0.4s too. Lastly, the strong similarities of P and PcP for some simple events excludes such large value of H. A dip with larger L and corresponding H surly produces stronger focusing effect, for example, a dip with L= 300km and H=3km will amplifies the PcP by 4˜5 times, but the waveform will be distorted seriously, contradictory to the similarity of P and PcP. So we speculate that the topography and other causes are combined to produce the high amplitude ratios together.

Wu, W.; Ni, S.

2009-05-01

207

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

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. The purpose of this project is to provide highly detailed and accurate datasets of select barrier islands and peninsular regions of Louisiana, Mississippi, Alabama, and Florida, acquired on June 27-30, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2009-01-01

208

EAARL Submerged Topography - U.S. Virgin Islands 2003  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived submerged topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), South Florida-Caribbean Network, Miami, FL; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate bathymetric datasets of a portion of the U.S. Virgin Islands, acquired on April 21, 23, and 30, May 2, and June 14 and 17, 2003. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2008-01-01

209

EAARL Topography - Natchez Trace Parkway 2007: First Surface  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Natchez Trace Parkway in Mississippi, acquired on September 14, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2008-01-01

210

EAARL Coastal Topography-Pearl River Delta 2008: First Surface  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the University of New Orleans (UNO), Pontchartrain Institute for Environmental Sciences (PIES), New Orleans, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Pearl River Delta in Louisiana and Mississippi, acquired March 9-11, 2008. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2009-01-01

211

EAARL Coastal Topography - Northeast Barrier Islands 2007: First Surface  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the northeast coastal barrier islands in New York and New Jersey, acquired April 29-30 and May 15-16, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2009-01-01

212

EAARL Coastal Topography - Fire Island National Seashore 2007  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) and bare earth (BE) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Northeast Coastal and Barrier Network, Kingston, RI; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of Fire Island National Seashore in New York, acquired on April 29-30 and May 15-16, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL) was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for pre-survey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2008-01-01

213

EAARL Coastal Topography-Pearl River Delta 2008: Bare Earth  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the University of New Orleans (UNO), Pontchartrain Institute for Environmental Sciences (PIES), New Orleans, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Pearl River Delta in Louisiana and Mississippi, acquired March 9-11, 2008. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2009-01-01

214

EAARL Coastal Topography - Northeast Barrier Islands 2007: Bare Earth  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) topography were produced collaboratively by the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the northeast coastal barrier islands in New York and New Jersey, acquired April 29-30 and May 15-16, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2008-01-01

215

EAARL Topography - Vicksburg National Military Park 2008: Bare Earth  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Vicksburg National Military Park in Mississippi, acquired on March 6, 2008. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2008-01-01

216

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

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of lidar-derived first-surface (FS) topography datasets were produced collaboratively by the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Kennedy Space Center, FL. This project provides highly detailed and accurate datasets of a portion of the eastern Florida coastline beachface, acquired on May 28, 2009. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative airborne lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multispectral color-infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine aircraft, but the instrument was deployed on a Pilatus PC-6. A single pilot, a lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the "bare earth" under vegetation from a point cloud of last return elevations.

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

2011-01-01

217

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

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of lidar-derived bare-earth (BE) and submerged topography datasets were produced collaboratively by the U.S. Geological Survey (USGS), St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL, and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of a portion of the Chandeleur Islands, acquired March 3, 2010. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative airborne lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multispectral color-infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations. For more information about similar projects, please visit the Decision Support for Coastal Science and Management website.

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

218

EAARL Topography - Jean Lafitte National Historical Park and Preserve 2006  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) and bare earth (BE) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Jean Lafitte National Historical Park and Preserve in Louisiana, acquired on September 22, 2006. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2008-01-01

219

EAARL Topography-Vicksburg National Military Park 2007: First Surface  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first-surface (FS) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the Vicksburg National Military Park in Mississippi, acquired on September 12, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2009-01-01

220

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

NASA Astrophysics Data System (ADS)

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.

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

1990-05-01

221

Dynamic evaluation of facial palsy by moire topography video  

NASA Astrophysics Data System (ADS)

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

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

1994-02-01

222

Topography of the Moon from the Clementine LIDAR  

NASA Astrophysics Data System (ADS)

Range measurements from the lidar instrument carried aboard the Clementine spacecraft have been used to produce an accurate global topographic model of the Moon. This paper discusses the function of the lidar; the acquisition, processing, and filtering of observations to produce a global topographic model; and the determination of parameters that define the fundamental shape of the Moon. Our topographic model: a 72nd degree and order spherical harmonic expansion of lunar radii, is designated Goddard Lunar Topography Model 2 (GLTM 2). This topographic field has an absolute vertical accuracy of approximately 100 m and a spatial resolution of 2.5 deg. The field shows that the Moon can be described as a sphere with maximum positive and negative deviations of approx. 8 km, both occurring on the farside, in the areas of the Korolev and South Pole-Aitken (S.P.-Aitken) basins. The amplitude spectrum of the topography shows more power at longer wavelengths as compared to previous models, owing to more complete sampling of the surface, particularly the farside. A comparison of elevations derived from the Clementine lidar to control point elevations from the Apollo laser altimeters indicates that measured relative topographic heights generally agree to within approx. 200 in over the maria. While the major axis of the lunar gravity field is aligned in the Earth-Moon direction, the major axis of topography is displaced from this line by approximately 10 deg to the cast and intersects the farside 24 deg north of the equator. The magnitude of impact basin topography is greater than the lunar flattening (approx. 2 km) and equatorial ellipticity (approx. 800 m), which imposes a significant challenge to interpreting the lunar figure. The floors of mare basins are shown to lie close to an equipotential surface, while the floors of unflooded large basins, except for S.P.-Aitken, lie above this equipotential. The radii of basin floors are thus consistent with a hydrostatic mechanism for the absence of significant farside maria except for S.P.-Aitken, whose depth and lack of mare require significant internal compositional and/or thermal heterogeneity. A macroscale surface roughness map shows that roughness at length scales of 101 - 102 km correlates with elevation and surface age.

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

1997-01-01

223

Topography of the Moon from the Clementine Lidar  

NASA Technical Reports Server (NTRS)

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

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

1997-01-01

224

EAARL Topography - George Washington Birthplace National Monument 2008  

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived bare earth (BE) and first surface (FS) topography were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Northeast Coastal and Barrier Network, Kingston, RI; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. This project provides highly detailed and accurate datasets of the George Washington Birthplace National Monument in Virginia, acquired on March 26, 2008. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL) was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is routinely used to create maps that represent submerged or first surface topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2009-01-01

225

The X-ray topography station at the Beijing synchrotron radiation facility  

Microsoft Academic Search

The features of the X-ray topography station at the Beijing Synchrotron Radiation Facility (BSRF) is presented. The major equipments, consisting of a white-radiation camera for X-ray topography, a versatile environmental chamber for in situ studies, an X-ray video imaging system for real-time observation, and a four-crystal camera for multiple crystal topography and high accuracy diffraction investigations, are described. Some experimental

Jianhua Jiang; Jiyong Zhao; Yulian Tian; Yong Han; Zhiyu Chao; Xiaoming Jiang; Dingchang Xian

1993-01-01

226

High-Resolution X-Ray Scattering Topography Using Synchrotron Radiation Microbeam  

Microsoft Academic Search

Although spatial resolution is the most essential factor determining the function of X-ray topography, it has not been improved in 30 years in spite of increasing requirements for highly-resolvable topography in materials science. X-ray scattering topography using a microbeam is a method capable of overcoming this resolution problem. Because the maximum resolution of an apparatus using a sealed-off tube is

Yoshinori Chikaura; Yoshifumi Suzuki; Hideki Kii

1994-01-01

227

Bistatic SAR coherence over non-planar topographies  

NASA Astrophysics Data System (ADS)

Monostatic Synthetic Aperture Radar (SAR) Coherent Change Detection (CCD) has been found to be of great utility in detecting changes that occur on the ground. Detectable changes of interest include vehicle tracks and water flow. The CCD procedure involves performing repeat pass radar collections, to form a coherence product, where ground disturbances can induce detectable incoherence. However there is usually a difference in the radar collection geometry which can lead to incoherent energy noise entering the CCD, which reduces the detectability of tracks. When sensing flat terrain, the incoherence due to collection geometry difference can be removed through a conventional Fourier image support trimming process. However, it has been found that when the terrain contains non-flat topography, the optimal trimming process is substantially more involved, so much so that a new per-pixel SAR back-projection imaging algorithm has been developed. This algorithm trims off incoherent energy on a per-pixel basis according to the local topography. In order to validate the bistatic SAR generalization to the monostatic per-pixel formalism and algorithm, bistatic change detection measurements were conducted with the GB-SAR system, and these are reported here.

Andre, Daniel B.; Morrison, Keith

2012-05-01

228

Topography and areal organization of mouse visual cortex.  

PubMed

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

Garrett, Marina E; Nauhaus, Ian; Marshel, James H; Callaway, Edward M

2014-09-10

229

A Martian general circulation experiment with large topography  

NASA Astrophysics Data System (ADS)

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.

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

1981-01-01

230

Ground motion in the presence of complex topography  

USGS Publications Warehouse

To study the influence of topography on ground motion, eight seismic recorders were deployed for a period of one year over Poverty Ridge on the east side of the San Francisco Bay Area, California. This location is desirable because of its proximity to local earthquake sources and the significant topographic relief of the array (439 m). Topographic amplification is evaluated as a function of frequency using a variety of methods, including reference?site?based spectral ratios and single?station horizontal?to?vertical spectral ratios using both shear waves from earthquakes and ambient noise. Field observations are compared with the predicted ground motion from an accurate digital model of the topography and a 3D local velocity model. Amplification factors from the theoretical calculations are consistent with observations. The fundamental resonance of the ridge is prominently observed in the spectra of data and synthetics; however, higher?frequency peaks are also seen primarily for sources in line with the major axis of the ridge, perhaps indicating higher resonant modes. Excitations of lateral ribs off of the main ridge are also seen at frequencies consistent with their dimensions. The favored directions of resonance are shown to be transverse to the major axes of the topographic features.

Hartzell, Stephen; Meremonte, Mark; Ramírez-Guzmán, Leonardo; McNamara, Daniel

2014-01-01

231

EAARL submarine topography: Florida Keys National Marine Sanctuary  

USGS Publications Warehouse

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.

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

2007-01-01

232

Lunar Topography: Results from the Lunar Orbiter Laser Altimeter  

NASA Technical Reports Server (NTRS)

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.

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

2012-01-01

233

EAARL Submarine Topography - Northern Florida Keys Reef Tract  

USGS Publications Warehouse

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.

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

2007-01-01

234

Smoking topography and outcome expectancies among individuals with schizotypy  

PubMed Central

Compared to smokers in the general population, smokers with schizophrenia smoke more cigarettes per day and have higher nicotine dependence and biochemical indicators of nicotine intake. They also have more intense smoking topography and greater positive smoking expectancies. Little is known about the relationship between smoking and schizotypy, defined as the personality organization reflecting a vulnerability to schizophrenia-spectrum pathology. This study assessed schizotypy symptoms, smoking characteristics and behaviors, and smoking expectancies in young adults with psychometrically defined schizotypy and demographically matched controls without schizotypy. Smokers with schizotypy had higher nicotine dependence and smoked more cigarettes per week compared to control smokers. They were also more likely to endorse greater positive consequences (i.e., improved state enhancement, stimulation, social facilitation, taste/sensorimotor manipulation, reduced negative affect and boredom) and fewer negative consequences of smoking. Smokers with schizotypy and control smokers did not differ on smoking topography or carbon monoxide levels. This is the first known study to investigate relationships between these smoking-related variables in smokers with schizotypy. Individuals with schizotypy possessed certain smoking-related characteristics and smoking expectancies similar to those with schizophrenia. This offers preliminary insight into unique smoking-related factors among individuals with schizotypy and highlights the importance of continued research in this area. PMID:23261186

Stewart, Diana W.; Vinci, Christine; Adams, Claire E.; Cohen, Alex S.; Copeland, Amy L.

2013-01-01

235

Mapping the global topography of the cost function in STELLOPT  

NASA Astrophysics Data System (ADS)

Stellarator designs have long been optimized for reduced neoclassical transport, but optimization for reduced turbulent transport is a relatively nascent research thrust. Recent work has addressedootnotetextH.E. Mynick, N. Pomphrey, P. Xanthopoulos, PRL 105, 095044 (2010) this ``turbulent optimization'' by using the GENE/GIST nonlinear gyrokinetic code and the STELLOPT stellarator optimization code. That work demonstrated that STELLOPT can produce stellarator designs that reduce the turbulent transport without adversely affecting other design metrics. STELLOPT utilizes a Levenberg-Marquardt (LM) algorithm to find a local minimum of a cost function in a shape space z of coefficients that define the plasma boundary. However, a visualization of the topography of the cost function in z space might reveal a lower global minimum and provide insight into why the LM algorithm missed it. The current work uses STELLOPT to provide this capability, replacing its LM algorithm with one that produces maps of the wider topography of the cost function. Analysis of these maps will be used to gain insight into the properties of the studied design configurations and to identify possible improvements to STELLOPT's optimization algorithm.

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

2011-11-01

236

Topography of Striate-Extrastriate Connections in Neonatally Enucleated Rats  

PubMed Central

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

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

2013-01-01

237

Modeling of fluidized ejecta emplacement over digital topography on Venus  

NASA Astrophysics Data System (ADS)

The FLOW computer model of McEwen and Malin (1989) modified for application to the study of Venus fluidized ejecta blankets (FEBs) demonstrates that relatively low viscosities, yield strengths, and initial velocities are required to duplicate the observed flow paths of the outflow materials. The model calculates the velocities and simulated flow paths of gravity flows over Magellan topography. The model is formulated to determine flow movements from initial conditions, gravitational acceleration, and resistance to motion as described by Coulomb, viscous, and turbulent resistance forces. Successful duplication of observed FEB flow paths has been achieved for the FEB craters Addams, Isabella, and Cochran. When used as a simple energy-line model, the model requires low coefficients of friction to extend FEBs to near their observed termini in the synthetic aperture radar (SAR) imagery, although the resulting straight flow lines do not follow the observed flow paths well. For Bingham flow, the model requires low values of viscosity and yield strength which are more similar to pyroclastic or debris flows than basaltic lavas. Flows of 100-m depth require 1 to 2 orders of magnitude higher values of both viscosity and yield strength than 10-m-deep flows. The complicated nature of the flow lines for the low velocity model suggests that FEBs were probably emplaced under variably laminar and turbulent flow conditions, where underlying topography influenced both the direction and energy of flow materials.

Johnson, Jeffrey R.; Gaddis, Lisa

238

Internal structure of Io and the global distribution of its topography  

NASA Astrophysics Data System (ADS)

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.

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

1990-06-01

239

Near-Field Scattering due to Topography and Lateral Velocity Heterogeneity  

NASA Astrophysics Data System (ADS)

The scattering of seismic waves traveling in the Earth is not only caused by velocity heterogeneity, but also by rough surface topography. Both factors are known to play an important role on ground motion complexity even at short distances from the source. In this study, we simulate ground motion with a 3D finite-difference wave propagation solver in the frequency band 0-5 Hz using different rough topography models and realistic heterogeneous media characterized by Von Karman correlation functions. We analyze the characteristics of the scattered wave-field, focusing in particular on coda waves. Our study shows that topography and velocity heterogeneity scattering generate coda waves with different characteristics. We notice that, while coda waves originated by velocity heterogeneity have a more diffusive nature presenting envelope broadening as a result of forward scattering, coda waves caused by topography scattering are composed of more coherent body and surface waves reflected and diffracted by irregular topography surface. Results indicate that, for shallow sources, topography scattering can generate more intense early-coda waves at short and intermediate distances from the source. As distance increases, velocity heterogeneity scattering starts to dominate. However results show a rather high degree of variability as topography scattering is very sensitive to source position and features of the topography model. On the other hand, velocity perturbations generate more intense late-coda waves We conclude that topography scattering cannot be used as a proxy for velocity heterogeneity scattering.

Imperatori, Walter; Mai, Martin

2014-05-01

240

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

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

241

Inferences About the Early Moon From Gravity and Topography  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

242

EAARL coastal topography--Alligator Point, Louisiana, 2010  

USGS Publications Warehouse

This project provides highly detailed and accurate datasets of a portion of Alligator Point, Louisiana, acquired on March 5 and 6, 2010. The datasets are made available for use as a management tool to research scientists and natural-resource managers. An innovative airborne lidar instrument originally developed at the National Aeronautics and Space Administration (NASA) Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multispectral color-infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit, which provide for sub-meter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine aircraft, but the instrument was deployed on a Pilatus PC-6. A single pilot, a lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of lidar data in an interactive or batch mode. Modules for presurvey flight-line definition, flight-path plotting, lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the "bare earth" under vegetation from a point cloud of last return elevations.

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

243

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

USGS Publications Warehouse

These remotely sensed, geographically referenced elevation measurements of Lidar-derived first surface (FS) elevation data were produced as a collaborative effort between the U.S. Geological Survey (USGS), Florida Integrated Science Center (FISC), St. Petersburg, FL; the National Park Service (NPS), Gulf Coast Network, Lafayette, LA; and the National Aeronautics and Space Administration (NASA), Wallops Flight Facility, VA. The project provides highly detailed and accurate datasets of select barrier islands and peninsular regions of Louisiana, Mississippi, Alabama, and Florida, acquired June 27-30, 2007. The datasets are made available for use as a management tool to research scientists and natural resource managers. An innovative airborne Lidar instrument originally developed at the NASA Wallops Flight Facility, and known as the Experimental Advanced Airborne Research Lidar (EAARL), was used during data acquisition. The EAARL system is a raster-scanning, waveform-resolving, green-wavelength (532-nanometer) Lidar designed to map near-shore bathymetry, topography, and vegetation structure simultaneously. The EAARL sensor suite includes the raster-scanning, water-penetrating full-waveform adaptive Lidar, a down-looking red-green-blue (RGB) digital camera, a high-resolution multi-spectral color infrared (CIR) camera, two precision dual-frequency kinematic carrier-phase GPS receivers, and an integrated miniature digital inertial measurement unit which provide for submeter georeferencing of each laser sample. The nominal EAARL platform is a twin-engine Cessna 310 aircraft, but the instrument may be deployed on a range of light aircraft. A single pilot, a Lidar operator, and a data analyst constitute the crew for most survey operations. This sensor has the potential to make significant contributions in measuring sub-aerial and submarine coastal topography within cross-environmental surveys. Elevation measurements were collected over the survey area using the EAARL system, and the resulting data were then processed using the Airborne Lidar Processing System (ALPS), a custom-built processing system developed in a NASA-USGS collaboration. ALPS supports the exploration and processing of Lidar data in an interactive or batch mode. Modules for presurvey flight line definition, flight path plotting, Lidar raster and waveform investigation, and digital camera image playback have been developed. Processing algorithms have been developed to extract the range to the first and last significant return within each waveform. ALPS is used routinely to create maps that represent submerged or sub-aerial topography. Specialized filtering algorithms have been implemented to determine the 'bare earth' under vegetation from a point cloud of last return elevations.

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

2009-01-01

244

Mapping the Topography of Europa: The Galileo-Clipper Story  

NASA Astrophysics Data System (ADS)

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

Schenk, Paul M.

2014-11-01

245

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

NASA Technical Reports Server (NTRS)

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

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

1990-01-01

246

Ion-beam-induced topography and surface diffusion  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

247

Different Approach to the Aluminium Oxide Topography Characterisation  

SciTech Connect

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.

Poljacek, Sanja Mahovic; Gojo, Miroslav [Faculty of Graphic Arts, University of Zagreb, Getaldiceva 2, 10000 Zagreb (Croatia); Raos, Pero; Stoic, Antun [Mechanical Engineering Faculty, J.J. Strossmayer University of Osijek, Trg Ivane Brlic Mazuranic 2, 35000 Slavonski Brod (Croatia)

2007-04-07

248

The American Geophysical Union Chapman Conference on Tectonics and Topography  

NASA Technical Reports Server (NTRS)

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.

1992-01-01

249

Recent and relict topography of Boo Bee patch reef, Belize  

USGS Publications Warehouse

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.

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

1977-01-01

250

Enhanced surface hydrophobicity by coupling of surface polarity and topography.  

PubMed

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

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

2009-09-01

251

Mercury's global shape and topography from MESSENGER limb images  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

252

New Orleans Topography, Radar Image with Colored Height  

NASA Technical Reports Server (NTRS)

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

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

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

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

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

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

2005-01-01

253

Topography of the Martian tropical regions with ISM  

NASA Astrophysics Data System (ADS)

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.

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

254

Leaf cuticle topography retrieved by using fringe projection  

NASA Astrophysics Data System (ADS)

The combination (often referred to as phase-stepping profilometry, PSP) of the fringe projection technique and the phase-stepping method allowed us to retrieve topographic maps of cuticles isolated from the abaxial surface of leaves; these were in turn sampled from an apple tree ( Malus domestica) of the variety Golden Delicious. The topographic maps enabled us to assess the natural features on the illuminated surface and also to detect the whole-field spatial variations in the thickness of the cuticle. Most of our attention was paid to retrieve the highly-resolved elevation information from the cuticle surface, which included the trace (in the order of tens of micrometers) left by ribs and veins. We expect that the PSP application for retrieving the cuticle topography will facilitate further studies on the dispersion and coverage of state-of-the-art agrochemical compounds meant to improve the defending properties of the cuticle. Methodological details are provided below.

Martínez, Amalia; Rayas, J. A.; Cordero, Raúl R.; Balieiro, Daniela; Labbe, Fernando

2012-02-01

255

Functional Topography of the Cerebellum in Verbal Working Memory  

PubMed Central

Speech—both overt and covert—facilitates working memory by creating and refreshing motor memory traces, allowing new information to be received and processed. Neuroimaging studies suggest a functional topography within the sub-regions of the cerebellum that subserve verbal working memory. Medial regions of the anterior cerebellum support overt speech, consistent with other forms of motor execution such as finger tapping, whereas lateral portions of the superior cerebellum support speech planning and preparation (e.g., covert speech). The inferior cerebellum is active when information is maintained across a delay, but activation appears to be independent of speech, lateralized by modality of stimulus presentation, and possibly related to phonological storage processes. Motor (dorsal) and cognitive (ventral) channels of cerebellar output nuclei can be distinguished in working memory. Clinical investigations suggest that hyper-activity of cerebellum and disrupted control of inner speech may contribute to certain psychiatric symptoms. PMID:20563894

Desmond, John E.

2010-01-01

256

The Shuttle Radar Topography Mission: A Global DEM  

NASA Technical Reports Server (NTRS)

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

Farr, Tom G.; Kobrick, Mike

2000-01-01

257

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

NASA Technical Reports Server (NTRS)

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

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

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

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

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

2001-01-01

258

Geologic structure of shallow maria. [topography of lunar maria  

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

259

Modeling of SAR signatures of shallow water ocean topography  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

260

Forecasting hurricane impact on coastal topography: Hurricane Ike  

USGS Publications Warehouse

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.

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

2010-01-01

261

Evaluating POLinSAR Tree Height and Topography Retrievals in Glen Affric  

NASA Astrophysics Data System (ADS)

In this paper we summarise recent results from the Glen Affric radar project aimed at evaluating polarimetric radar interferometry for providing vegetation canopy height and bald-earth topography. We present a comparison of results from L-band repeat pass SAR imagery with detailed in-situ measurements of forest height and topography.

Woodhouse, I. H.; Cloude, S.; Papathanassiou, K.; Hutchinson, C.

2003-04-01

262

A role for surface topography in creating and maintaining bone at titanium endosseous implants  

Microsoft Academic Search

Statement of problem. A variety of claims are made regarding the effects of surface topography on implant osseointegration. Many in vivo and in vitro experimental observations have key limitations in their interpretations. Purpose. This review considers the major claims made concerning the effects of commercially pure (cp) titanium implant surface topography on osseointegration. Important findings of consensus are highlighted, and

Lyndon F. Cooper

2000-01-01

263

A laboratory study of low-mode internal tide scattering by finite-amplitude topography  

E-print Network

A laboratory study of low-mode internal tide scattering by finite-amplitude topography Thomas concerning the scattering of a low-mode internal tide by finite-amplitude Gaussian topography. Experiments produces significant reflection of the internal tide and transfer of energy from low to high modes. © 2009

Dauxois, Thierry

264

Topography of Responses in Conditional Discrimination Influences Formation of Equivalence Classes  

ERIC Educational Resources Information Center

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…

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

2008-01-01

265

Constraints on 3-D stress in the crust from support of mid-ocean ridge topography  

E-print Network

is the morphologic result of rifting, magmatism, and trans- form faulting associated with seafloor spreading driven of these stresses may be constrained using seafloor topography and gravity. The topography is divided into a short the slow spreading mid-Atlantic ridge, 40­50 MPa along the ultra­slow spreading ridges in the western

Sandwell, David T.

266

Internal wave generation from rough topography D. A. Aguilar and B. R. Sutherlanda  

E-print Network

Internal wave generation from rough topography D. A. Aguilar and B. R. Sutherlanda Department examine internal wave generation above and in the lee of finite-amplitude periodic topography having various degrees of roughness. We show that internal waves are generated not only by flow over the hills

Sutherland, Bruce

267

A thermomechanical study of the effects of mold topography on the solidification of Aluminum alloys  

E-print Network

1 A thermomechanical study of the effects of mold topography on the solidification of Aluminum-3801, USA A thermomechanical study of the effects of mold topography on the solidification of Aluminum alloys at early times is provided. The various coupling mechanisms between the solid-shell and mold

Zabaras, Nicholas J.

268

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

E-print Network

the mission life-time > Monitor seasonnal 3D topography dynamics > Instrument · Combination of activeZ-Earth Global dynamic topography at very-high resolution for Geohazards, Climate Change and Vulnerability mapping Thomas Dewez (PI of Z-Earth consortium) t.dewez@brgm.fr Proposal to ESA's Earth Explorer 8

Berthier, Etienne

269

Gravity-Driven flow of evaporating thin liquid films over substrates with topography  

E-print Network

) into the flow Figure 1: Gravity-driven flow down an inclined plane with topography of thin water films over #12;a thin layer of liquid, thickness h(x,y), flows over a topography s(x,y) on a substrate inclined inclined substrates and extends the recent numerical analysis of these flows, by (Gaskell et al 2003b

Jimack, Peter

270

Characterization and quantification of data voids in the shuttle Radar topography mission data  

Microsoft Academic Search

The goal of this study was to characterize and quantify the occurrence of data voids in data from the Shuttle Radar Topography Mission (SRTM) for the conterminous United States. For this purpose, SRTM data and corresponding data from the national elevation data were downloaded in 21 samples spatially organized to cover the main topography of the U.S. Void locations in

Ola Hall; Giacomo Falorni; Rafael L. Bras

2005-01-01

271

Relationships between extreme daily precipitation and topography in a mountainous region: a case study in Scotland  

Microsoft Academic Search

The spatial pattern of precipitation is known to be highly dependent on meteorological conditions and relief. But the relationships between precipitation and topography in mountainous areas are not very well known, partly because of the complex topography in these regions, and partly because of the sparsity of information available to study such relationships in high elevation areas. Moreover, studies are

Christel Prudhomme; Duncan W. Reed

1998-01-01

272

Observation of chirality domains in terbium by polarized neutron diffraction topography  

E-print Network

1279 Observation of chirality domains in terbium by polarized neutron diffraction topography J, dans un monocristal de terbium porté dans sa phase hélimagnétique, par topographies aux neutrons observation of spiral spin or chirality domains, in a single crystal of terbium in its helimagnetic phase

Paris-Sud XI, Université de

273

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

USGS Publications Warehouse

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

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

1985-01-01

274

Representation of Topography by Shaved Cells in a Height Coordinate Ocean Model  

Microsoft Academic Search

Height coordinate ocean models commonly represent topography as a ''staircase'' of discontinuous steps that are fitted to the model grid. Here the ramifications of an alternative approach are studied in which ''shaved cells'' are used to represent irregular topography. The problem is formulated using the finite-volume method and care is taken to ensure that the discrete forms have appropriate conservation

Alistair Adcroft; Chris Hill; John Marshall

1997-01-01

275

A Perceptual Study on Haptic Rendering of Surface Topography when Both Surface Height and Stiffness Vary  

E-print Network

A Perceptual Study on Haptic Rendering of Surface Topography when Both Surface Height and Stiffness of surface topography when both surface height and surface stiffness vary. Three psychophysical experiments that the threshold for detecting a height difference between two adjacent planes was quite small (0.17-0.63 mm

Tan, Hong Z.

276

Three-dimensional optical topography of brain activity in infants watching videos of human movement  

Microsoft Academic Search

We present 3D optical topography images reconstructed from data obtained previously while infants observed videos of adults making natural movements of their eyes and hands. The optical topography probe was placed over the temporal cortex, which in adults is responsible for cognitive processing of similar stimuli. Increases in oxyhaemoglobin were measured and reconstructed using a multispectral imaging algorithm with spatially

Teresa Correia; Sarah Lloyd-Fox; Nick Everdell; Anna Blasi; Clare Elwell; Jeremy C Hebden; Adam Gibson

2012-01-01

277

Topography and geomorphology of the Huygens landing site on Titan  

USGS Publications Warehouse

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.

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

278

Nicotine intake and smoking topography in smokers with bipolar disorder  

PubMed Central

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

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

2013-01-01

279

Diet and dental topography in pitheciine seed predators.  

PubMed

Pitheciines (Pithecia, Chiropotes, and Cacajao) are a specialized clade of Neotropical seed predators that exhibit postcanine teeth with low and rounded cusps and highly crenulated occlusal surface enamel. Data on feeding ecology show that Pithecia consumes proportionally more leaves than other pitheciine species, and comparative studies demonstrate its greater molar relief and relative shearing potential. However, data on pitheciine food mechanics show that Pithecia masticates seeds with greater crushing resistance than those preferred by Chiropotes. This variation predicts an opposing morphology characterized by low and more rounded occlusal surfaces in Pithecia. We build on previous research using new methods for molar surface shape quantification by examining pitheciine second molar shearing crest length, occlusal relief, surface complexity, and surface curvature relative to nonseed specializing platyrrhines and within the context of the observed interspecific variation in pitheciine feeding ecology. Consistent with the previous analyses, our findings demonstrate that pitheciine molars exhibit low shearing, relief, and curvature compared with nonseed predators, independent of phylogeny. Pitheciines also exhibit highly "complex" occlusal topography that promotes the efficient breakdown of tough seed tissues. Overall, Pithecia, Chiropotes, and Cacajao share a similar topographic pattern, suggesting adaptation to foods with similar structural and/or mechanical properties. However, Cacajao differs in surface complexity, which reflects some variation in its feeding ecology. Contrary to the predictions, Pithecia and Chiropotes do not differ in any of the topographic variables examined. The range of demands imposed on the postcanine teeth of Pithecia might therefore select for an average topography, one that converges on that of Chiropotes. PMID:23212472

Ledogar, Justin A; Winchester, Julia M; St Clair, Elizabeth M; Boyer, Doug M

2013-01-01

280

Fractional snow-covered area parameterization over complex topography  

NASA Astrophysics Data System (ADS)

Fractional snow-covered area (SCA) is a key parameter in large-scale hydrological, meteorological and climate models. Since SCA affects albedos and surface energy balance fluxes, it is especially of interest over mountainous terrain where generally a reduced SCA is observed in large grid cells. Temporal and spatial snow distributions are however difficult to measure over complex topography. We therefore present a parameterization of the SCA based on a new subgrid parameterization for the standard deviation of snow depth over complex topography. Highly-resolved snow depth data at peak of winter were used from two distinct climatic regions, in eastern Switzerland and in the Spanish Pyrenees. Topographic scaling parameters are derived assuming Gaussian slope characteristics. We use computationally cheap terrain parameters, namely the correlation length of subgrid topographic features and the mean squared slope. A scale dependent analysis was performed by randomly aggregating the alpine catchments in domain sizes ranging from 50 m to 3 km. For the larger domain sizes, snow depth was predominantly normally distributed. Trends between terrain parameters and standard deviation of snow depth were similar for both climatic regions, allowing to parameterize the standard deviation of snow depth based on terrain parameters. To make the parameterization widely applicable, we introduced the mean snow depth as a climate indicator. Assuming a normal snow distribution and spatially homogeneous melt, snow cover depletion curves were derived for a broad range of coefficients of variations. The most accurate closed form fit resembled an existing SCA parameterization. By including the subgrid parameterization for the standard deviation of snow depth, we extended the SCA parameterization for topographic influences. For all domain sizes we obtained errors lower than 10% between measured and parameterized SCA.

Helbig, N.; van Herwijnen, A.; Magnusson, J.; Jonas, T.

2014-08-01

281

In need of combined topography and bathymetry DEM  

NASA Astrophysics Data System (ADS)

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

Kisimoto, K.; Hilde, T.

2003-04-01

282

Harmonic and statistical analyses of the gravity and topography of Vesta  

NASA Astrophysics Data System (ADS)

We examine the gravity and topography of the asteroid 4 Vesta, as recently revealed by the Dawn mission. The observed gravity is highly correlated with the observed topography, and suggests little lateral variation in density. The variance spectra of both gravity and topography follow power laws which are very similar to those seen for the Moon, Mars, Venus, and Earth. A significant way in which Vesta differs from these larger silicate bodies is that both gravity and topography are significantly anisotropic, with more north-south variation than east-west variation. Rapid rotation plausibly contributes to this anisotropy, but only at harmonic degree two. The remainder of the anisotropy appears related to the large impacts which formed the Rheasilvia and Veneneia basins. We note that, as usual, gravitational inverse problems are non-unique. While the observed gravity and topography of Vesta do not preclude existence of a metallic core, they certainly do not require it.

Bills, Bruce G.; Asmar, Sami W.; Konopliv, Alexander S.; Park, Ryan S.; Raymond, Carol A.

2014-09-01

283

Radiation and Dissipation of Internal Waves Generated by Geostrophic Motions Impinging on Small-Scale Topography: Theory  

E-print Network

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

Nikurashin, Maxim

284

Observations and HighObservations and High--Resolution Modeling of SmallResolution Modeling of Small--Scale FlowScale Flow--TopographyTopography Interactions Near Caribbean Coral ReefsInteractions Near Caribbean Coral Reefs  

E-print Network

of Small--Scale FlowScale Flow--TopographyTopography Interactions Near Caribbean Coral ReefsInteractions Near Caribbean Coral Reefs Tal Ezer Center for Coastal Physical Oceanography, Old Dominion University-topography interactions near coral reefs off the coast of Belize. Model results show that reefs with a unique shape

Ezer,Tal

285

UNIVERSITYOF HAWAI'I lIl3RARY INTERNAL TIDE SCATTERING AT M1DOCEAN TOPOGRAPHY  

E-print Network

UNIVERSITYOF HAWAI'I lIl3RARY INTERNAL TIDE SCATTERING AT M1DOCEAN TOPOGRAPHY A DISSERTATION The scattering ofmode-oneM, internal tides from I) idealized Gaussian topography and 2) the Line Islands Ridge is examined with a primitive equation numerical model. Internal tide scattering at topography leads to a loss

Luther, Douglas S.

286

A coupled thermomechanical, thermal transport and segregation analysis of the solidification of Aluminum alloys on molds of uneven topographies  

E-print Network

of Aluminum alloys on molds of uneven topographies Deep Samantaa and Nicholas Zabarasa a Materials Process the mold-metal interface, are observed for different mold topographies during the early stages in the melt, melt superheat and varying mold surface topography on nucleation of air- gaps and evolution

Zabaras, Nicholas J.

287

Anomalous Accretionary Margin Topography Formed By Repeated Earthquakes  

NASA Astrophysics Data System (ADS)

It has long been recognized that accretionary margins of major subduction zones undergo substantial deformation. However even with the large amounts of shortening accommodated within the margin, for most subduction zones, there is an extended submarine portion to the accretionary, highly-deformed upper-plate between the trench and the coast. This is a vexing situation since this submarine section typically overlies the actual locked or coupled patch of the plate interface. The result of this is added difficulty in directly observing processes related to the plate interface coupling - such processes as micro-seismicity and the actual patterns of plate coupling. There are a few locations globally in which there are sub-aerially exposed terranes that lie closer to the trench and overlie the inferred coupled or seismogenic portion of the plate interface. Such regions have taken on significance in subduction zone studies as they provide locations to observe the plate interface coupling effects in the near-field. In particular the Pacific coast of Costa Rica provides such a location, and there has been substantial geologic, geophysical, and geodetic research exploiting the positions of these near-trench peninsulas (Nicoya, Osa, and Burica). These sites provide near-field access to plate-interface processes, but whether they represent typical subduction zone behavior remains an open question as the deformational processes or inherited structures that have produced this anomalous topography are not well constrained. Simply put, if the existence of these sub-aerial, near-trench terranes is a result of anomalous behavior on the plate interface (as has been suggested), then their utility in providing high-fidelity near-field insight into the plate interface properties and processes is substantially reduced. Here we propose a new mechanism that could be responsible for the formation of both the Nicoya and Osa Peninsulas in the past, and is currently producing a third peninsula - the Burica Peninsula at the intersection of the Panama fracture zone and the margin. Specifically we propose that the anomalous topography along the Pacific coast of Costa Rica has been produced by repeated, great subduction earthquakes that have ruptured across the boundary separating the Cocos and Nazca plates - the subducted continuation of the Panama fracture zone. The pattern of upper-plate shortening generated by such a process (documented in the 2007 Mw 8.1 Solomon Islands earthquake, which produced co-seismic localized uplift above the subducted transform plate boundary) convolved with the migration history of the Panama triple junction (PTJ) is proposed as the mechanism to produce substantial along-margin, long-lived accretionary margin topography. Specifically we argue that repeated great subduction earthquakes that rupture across fundamental plate boundary structures can produce substantial, long-lived upper plate deformation above the inter-seismically coupled plate interface.

Furlong, Kevin P.

2014-05-01

288

Isostasy, dynamic topography, and the elevation of the Apennines of Italy  

NASA Astrophysics Data System (ADS)

The elevation of an orogenic belt is commonly related to crustal/lithosphere thickening. Here, we discuss the Apennines as an example to show that topography at a plate margin may be controlled not only by isostatic adjustment but also by dynamic, mantle-driven processes. Using recent structural constraints for the crust and mantle we find that the expected crustal isostatic component explains only a fraction of the topography of the belt, indicating positive residual topography in the central Apennines and negative residual topography in the northern Apennines and Calabria. The trend of the residual topography matches the mantle flow induced dynamic topography estimated from regional tomography models. We infer that a large fraction of the Apennines topography is related to mantle dynamics, producing relative upwellings in the central Apennines and downwellings in the northern Apennines and Calabria where subduction is still ongoing. Comparison between geodetic and geological data on vertical motions indicates that this dynamic process started in the early Pleistocene and the resulting uplift appears related to the formation and enlargement of a slab window below the central Apennines. The case of the Apennines shows that at convergent margins the elevation of a mountain belt may be significantly different from that predicted solely by crustal isostasy and that a large fraction of the elevation and its rate of change are dynamically controlled by mantle convection.

Faccenna, Claudio; Becker, Thorsten W.; Miller, Meghan S.; Serpelloni, Enrico; Willett, Sean D.

2014-12-01

289

The 3D brain topography based on PC  

Microsoft Academic Search

Brain topographic mapping is a useful technique for visualizing brain activity. It clarifies the spatial and temporal relationships between different cortical areas. However, 3D topographic mapping systems are only available in dedicated image processing and image synthesis workstation environments. In this paper, we aim at a PC-based 3D topographic mapping system, which is simple, low-cost and easy to operate. This

K. H. Kim; J. H. Kwon; D. H. Lee; S. I. Kim

1997-01-01

290

Discriminant analysis of functional optical topography for schizophrenia diagnosis  

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

291

Crater Topography on Titan: Implications for Landscape Evolution  

NASA Technical Reports Server (NTRS)

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.

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

292

Wind-Related Topography in Phoenix's Region of Mars (Animation)  

NASA Technical Reports Server (NTRS)

[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.

2008-01-01

293

Crustal structure of Mars from gravity and topography  

NASA Technical Reports Server (NTRS)

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.

Neumann, G. A.; Zuber, M. T.; Wieczorek, M. A.; McGovern, P. J.; Lemoine, F. G.; Smith, D. E.

2004-01-01

294

STS-99 Shuttle Radar Topography Mission Stability and Control  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

295

Retinal ganglion cell topography in juvenile harbor seals (Phoca vitulina).  

PubMed

Retinal topography in juvenile harbor seals (Phoca vitulina) was analyzed in retinal wholemounts stained with cresyl violet. A region of highest ganglion cell density, i.e., an area centralis, was identified in the temporal retina at a mean distance of 7.7 mm from the papilla (mean peak ganglion cell density 3,952 cells/mm(2)). With an estimated posterior nodal distance of 21 mm, this value corresponds to 531 cells/deg(2). Retinal resolution was calculated as 11.5 cycles/deg under water and 8.7 cycles/deg in air, which is better than the corresponding behaviorally assessed visual acuities. In the region of high ganglion cell density, the ganglion cell layer comprised 1-2 cell layers. From there a moderate visual streak with a ganglion cell density of approximately 1,000 cells/mm(2) extended into the nasal retina. The latter two features together with the absolute ganglion cell density render the harbor seal retina more similar to that of terrestrial carnivores than to that of other pinnipeds. PMID:19690408

Hanke, Frederike D; Peichl, Leo; Dehnhardt, Guido

2009-01-01

296

Interferometric estimation of ice sheet motion and topography  

NASA Technical Reports Server (NTRS)

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.

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

1997-01-01

297

Hydrodynamic modeling for river delta salt marshes using lidar topography  

NASA Astrophysics Data System (ADS)

Topographic data from lidar and multi-beam sonar create new challenges for hydrodynamic models of estuaries, tidelands, and river deltas. We now can readily obtain detailed elevation data on 1 m scales and finer, but solving hydrodynamics with model grid cells at these small scales remains computationally prohibitive (primarily because of the small time step required for small grid cells). Practical estuarine models for the next decade or so will likely have grid scales in the range of 5 to 15 m. So how should we handle known subgrid-scale features? Simply throwing out known data does not seem like a good idea, but there is no consensus on how best to incorporate knowledge of subgrid topography into either hydrodynamic or turbulence models. This presentation discusses both the theoretical foundations for modeling subgrid-scale features and the challenges in applying these ideas in the salt marshes of a river delta. The subgrid problem highlights some important areas for field and laboratory research to provide calibration parameters for new models that upscale the effects of known subgrid features.

Hodges, Ben R.

2014-05-01

298

OCT 3-D surface topography of isolated human crystalline lenses.  

PubMed

Quantitative 3-D Optical Coherence Tomography was used to measure surface topography of 36 isolated human lenses, and to evaluate the relationship between anterior and posterior lens surface shape and their changes with age. All lens surfaces were fitted to 6th order Zernike polynomials. Astigmatism was the predominant surface aberration in anterior and posterior lens surfaces (accounting for ~55% and ~63% of the variance respectively), followed by spherical terms, coma, trefoil and tetrafoil. The amount of anterior and posterior surface astigmatism did not vary significantly with age. The relative angle between anterior and posterior surface astigmatism axes was on average 36.5 deg, tended to decrease with age, and was >45 deg in 36.1% lenses. The anterior surface RMS spherical term, RMS coma and 3rd order RMS decreased significantly with age. In general, there was a statistically significant correlation between the 3rd and 4th order terms of the anterior and posterior surfaces. Understanding the coordination of anterior and posterior lens surface geometries and their topographical changes with age sheds light into the role of the lens in the optical properties of the eye and the lens aging mechanism. PMID:25360371

Sun, Mengchan; Birkenfeld, Judith; de Castro, Alberto; Ortiz, Sergio; Marcos, Susana

2014-10-01

299

Display of Magellan SAR and Topography Data in Google Earth  

NASA Astrophysics Data System (ADS)

Much of our understanding of the geodynamics and geology of Venus has been derived from radar imagery and topography from the Magellan mission (NASA 1989-1994). These data were archived at the Planetary Data System (PDS) and are easily and freely available. Unfortunately, the Magellan Venus data are far less accessible than those of the Earth, Mars, and the Moon. Data for these bodies are available via the Google Earth geobrowser, allowing anyone to easily explore the latest imagery and surface information. In an effort to promote public interest in Venus, we have created content for Google Earth that displays three types of information from the Magellan-era. First the FMAP compilation of the Magellan SAR imagery has been assembled into a global overlay image for rapid panning and zooming. Second, the reprocessed altimetry data [Ford and Pettingell, 1992; Rappaport et al. 1999] have been carefully edited and merged with a global spherical harmonic analysis [Wieczorek, 2007] to form a 10-km resolution global DEM of the planet. Finally the IAU feature names along with the content from ``The Face of Venus'' [Roth and Wall, 1995] have been assembled as an overlay to provide basic naming and geology information. A draft version of this material is available by adding this Network Link in Google Earth: http://byss.arc.nasa.gov/ge-venus/venus.kml. We welcome comments and suggestions on how to best represent Venus data for the public

Beyer, R. A.; Mehnert, E.; Sandwell, D. T.; Kolb, E.; Austin Foulkes, J.; Schwehr, K.; Johnson, C. L.

2012-12-01

300

Determining Titan surface topography from Cassini SAR data  

USGS Publications Warehouse

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.

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

301

Fractal analysis of surface topography in ground monocrystal sapphire  

NASA Astrophysics Data System (ADS)

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.

Wang, Qiuyan; Liang, Zhiqiang; Wang, Xibin; Zhao, Wenxiang; Wu, Yongbo; Zhou, Tianfeng

2015-02-01

302

Shuttle Radar Topography Mission - New Products in 2005  

USGS Publications Warehouse

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.

U.S. Geological Survey

2007-01-01

303

Contact Line Pinning by Microfabricated Patterns: Effects of Microscale Topography  

PubMed Central

We study how the microscale topography of a solid surface affects the apparent advancing and receding angles at the contact line of a liquid drop pinned to this surface. Photolithographic methods are used to produce continuous circular polymer rings of varying cross-sectional size and shape on hydrophilic silicon wafer surfaces. Drops of water and glycerol are dispensed into the areas bounded by these rings, and critical apparent advancing and receding angles are measured and correlated with the parameters that characterize the ring cross-section. For much of the examined parameter space, the apparent critical angles are independent of ring height and width and are determined primarily by the slope of the ring's sidewalls, consistent with a model due to Gibbs. For ring heights below a few micrometers, the critical angles decrease below the values predicted by the sidewall slopes alone. These results provide data for calculation of hysteresis on naturally rough surfaces, and demonstrate a simple method for controlling and enhancing contact line pinning on solid surfaces. PMID:19317420

Kalinin, Yevgeniy V.; Berejnov, Viatcheslav; Thorne, Robert E.

2010-01-01

304

Snow, topography, and the diurnal cycle in streamflow  

USGS Publications Warehouse

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.

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

2002-01-01

305

Extraction of Martian valley networks from digital topography  

NASA Technical Reports Server (NTRS)

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.

Stepinski, T. F.; Collier, M. L.

2004-01-01

306

Automated object-based classification of topography from SRTM data  

PubMed Central

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

Dr?gu?, Lucian; Eisank, Clemens

2012-01-01

307

Assessing Gravity Estimates to Improve Dynamic Ocean Topography  

NASA Astrophysics Data System (ADS)

Dynamic ocean topography (DOT), which defines the streamlines of ocean circulation, can be computed from the difference between mean sea surface (MSS) measurements (e.g. from satellite altimetry) and the Earth's geoid (from gravity observations). Uncertainties in the geoid translate into uncertainties in DOT, and this is particularly an issue for smaller length-scales. We estimate these uncertainties at various length-scales by comparing GRACE and GOCE-based geoid products with MSS and DOT products. Geoid and mean sea surface height fields are then combined to constrain the DOT in an assimilating ocean model, the Southern Ocean State Estimate (SOSE). Uncertainties in the small-scale geoid are accounted for with a prescribed error variance. The large-scale geoid errors are accounted for by solving for a smooth error field representing misfit to geoid model estimates. This error field minimizes the impact of correlated errors in the geoid on the optimization, while providing a metric for evaluating the consistency estimate of SOSE relative to the geoid products. For the EGM08 and TIMR3 geoid fields, our analysis for the Southern Ocean shows that error variances tend to be largest in small-scale regions associated with large topographic features. Error covariance magnitudes imply regional differences between the two products.

Gille, S. T.; Krzemien, T.; Mazloff, M. R.; Cornuelle, B. D.

2013-12-01

308

Shielded piezoresistive cantilever probes for nanoscale topography and electrical imaging  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

309

A Revolution in Mars Topography and Gravity and Magnetic Fields  

NASA Technical Reports Server (NTRS)

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.

Smith, David E.

2002-01-01

310

The GMRT: System Parameters and Current Status  

E-print Network

, albeit for only one polarisation per band. 1.2 Electronics At the focus of each antenna, each feed has 2 Overview 2 1.1 Antennas & Feeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Electronics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.3 Software based

Udgaonkar, Jayant B.

311

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)

The use of Light Detection and Ranging (lidar) derived topography has become an indispensable tool in Earth science research. The collection of high-resolution lidar topography from an airborne or terrestrial platform allows landscapes and landforms to be represented at sub-meter resolution and in three dimensions. In addition to its high value for scientific research, lidar derived topography has tremendous potential as a tool for Earth science education. Recent science education initiatives and a community call for access to research-level data make the time ripe to expose lidar data and derived data products as a teaching tool. High resolution topographic data fosters several Disciplinary Core Ideas (DCIs) of the Next Generation Science Standards (NGS, 2013), presents respective Big Ideas of the new community-driven Earth Science Literacy Initiative (ESLI, 2009), teaches to a number National Science Education Standards (NSES, 1996), and Benchmarks for Science Literacy (AAAS, 1993) for science education for undergraduate physical and environmental earth science classes. The spatial context of lidar data complements concepts like visualization, place-based learning, inquiry based teaching and active learning essential to teaching in the geosciences. As official host to EarthScope lidar datasets for tectonically active areas in the western United States, the NSF-funded OpenTopography facility provides user-friendly access to a wealth of data that is easily incorporated into Earth science educational materials. OpenTopography (www.opentopography.org), in collaboration with EarthScope, has developed education and outreach activities to foster teacher, student and researcher utilization of lidar data. These educational resources use lidar data coupled with free tools such as Google Earth to provide a means for students and the interested public to visualize and explore Earth's surface in an interactive manner not possible with most other remotely sensed imagery. The education section of the OpenTopography portal has recently been strengthened with the addition of several new resources and the re-organization of existing content for easy discovery. New resources include a detailed frequently asked questions (FAQ) section, updated 'How-to' videos for downloading data from OpenTopography and additional webpages aimed at students, educators and researchers leveraging existing and updated resources from OpenTopography, EarthScope and other organizations. In addition, the OpenLandform catalog, an online collection of classic geologic landforms depicted in lidar, has been updated to include additional tectonic landforms from EarthScope lidar datasets.

Kleber, E.; Crosby, C. J.; Arrowsmith, R.; Robinson, S.; Haddad, D. E.

2013-12-01

312

Topography effects in the 1999 Athens earthquake : engineering issues in seismology  

E-print Network

It is well known that irregular topography can substantially affect the amplitude and frequency characteristics of seismic motion. Macroseismic observations of destructive earthquakes often show higher damage intensity at ...

Assimaki, Dominic, 1975-

2004-01-01

313

Belonging: Cultural Topographies of Identity University College Dublin, Friday 8th to Saturday 9th  

E-print Network

Belonging: Cultural Topographies of Identity University College Dublin, Friday 8th to Saturday 9th 2012 to: Dr Alison Ribeiro de Menezes School of Languages and Literatures University College Dublin Belfield Dublin 4 Ireland alison.menezes@ucd.ie #12;

314

Degree variances of the earth's potential, topography and its isostatic compensation  

NASA Technical Reports Server (NTRS)

A spherical harmonic expansion of the earth's gravitational potential and equivalent rock topography to degree and order 180 is described. The potential implied by the topography considered as uncompensated and with isostatic compensation has been computed. Good agreement with the observed potential field is found when the depth of compensation in the Airy theory is assumed to be 50 km. At the higher degrees the correlation coefficient between the potential expansion and the equivalent rock topography is about 0.5. The Lachapelle equations for the topographic isostatic potential were tested using 1 x 1 deg equivalent rock topography. The degree variances agree at the lower degrees but at degree 36 the Lachapelle results using 5 deg data underestimate the potential degree variances by about one-third.

Rapp, R. H.

1982-01-01

315

Experimental investigation of internal tide generation by two-dimensional topography using synthetic Schlieren  

E-print Network

An experimental investigation of internal tide generation at two-dimensional topography was carried out using the synthetic Schlieren experimental technique. Two linear models were tested: Balmforth, Ierley and Young's [1] ...

Echeverri Mondragón, Paula

2006-01-01

316

A laboratory study of low-mode internal tide scattering by finite-amplitude topography  

E-print Network

We present the first laboratory experimental results concerning the scattering of a low-mode internal tide by finite-amplitude Gaussian topography. Experiments performed at the Coriolis Platform in Grenoble used a recently ...

Peacock, Thomas

317

An Analysis of the Effect of Topography on the Martian Hadley Cells  

E-print Network

Previous work with Mars general circulation models (MGCMs) has shown that the north–south slope in Martian topography causes asymmetries in the Hadley cells at equinox and in the annual average. To quantitatively solve for ...

Plumb, R. Alan

318

INFLUENCE OF VEGETATION, TOPOGRAPHY, AND ROADS ON COUGAR MOVEMENT IN SOUTHERN CALIFORNIA  

E-print Network

- nivore studies. We examined the movements of 10 female and 7 male cougars (Puma concolor) at 15-min, cougar, habitat selection, movement, prey trap, Puma concolor, ripar- ian, roads, scale, topography

Beier, Paul

319

High Resolution Global Topography of Itokawa from Hayabusa Imaging and LIDAR Data  

NASA Technical Reports Server (NTRS)

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.

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

320

Emplacement of Long Lava Flows: Detailed Topography of the Carrizozo Basalt Lava Flow, New Mexico  

NASA Technical Reports Server (NTRS)

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.

Zimbelman, J. R; Johnston, A. K.

2000-01-01

321

A new, earth-based radar technique for the measurement of lunar topography  

Microsoft Academic Search

Radio interferometry is a new technique for the measurement of the surface topography of the Moon. Elevation data may be obtained directly without regard for unambiguously-identified features, for any lunar surface element that yields a recognizable radar echo.

S. H. Zisk

1972-01-01

322

Crater Detection from Venus Digital Topography and Comparison with Martian and Lunar Craters  

NASA Astrophysics Data System (ADS)

We used a crater detection algorithm (CDA) for detection of craters from Venus digital topography and computation of the depth/diameter ratio. The results were compared with the accompanying results for martian and lunar craters.

Salamuni?car, G.; Lon?ari?, S.

2012-03-01

323

Tectonics of the Tharsis Region of Mars: Insights from MGS Topography and Gravity  

NASA Technical Reports Server (NTRS)

We have investigated the Tharsis region using gravity, topography, and geology to constrain a spherical thin shell model. We find that Tharsis likely formed primarily by volcanic construction, and has been largely unchanged since the Noachian.

Banerdt, W. Bruce; Golombek, Matthew P.

2000-01-01

324

Building topography in Cyprus and south Turkey: geological constraints and geodynamic models  

NASA Astrophysics Data System (ADS)

We present a regional synthesis of the geometries and Neogene vertical motions and horizontal deformations of the central sector of the Cyprus arc-trench system, which are used to constrain 2D thermo-mechanical numerical models. We used depth-converted seismic reflection lines, basin analysis techniques and fieldwork observations, combined with available literature. From the Cyprus arc trench to the Central Anatolia Plateau, three independent vertical motion domains are identified: the Cyprus structural high; the Cilicia Basin and the Tauride Range. Early Miocene regional subsidence that still continues in the Cilicia Basin was disrupted by surface uplift in the north and south domains during Late Miocene or younger times. Coevally, N-S shortening developed regional contractional structures along the margin. The large-wavelength Miocene monocline fold that formed in S Turkey reveals relative vertical displacement rates of 0.5 mm/y and horizontal shortening values of <1%, along our studied sections. Shortening led to S-dipping thrusts in the center of the Cilicia Basin, and further developed the S-verging Kyrenia thrust system in N Cyprus. The observed deformation patterns and associated vertical motions suggest that the Anatolian upper-plate topography, including the uplifted south Turkey, results from wedge deformation in relation to the Cyprus arc. We use numerical finite element models to test this hypothesis. Models show that the mechanical growth of both the Anatolian accretionary complex and its forearc basin system caused sedimentary thickening and overburden, which led to the development of a sedimentary blanket that started to control the thermal distribution in the margin; relative temperatures decreased within the blanket and increased underneath it. This resulted in thermally weakened viscous deformation of the lower crust, which eventually forced the surface uplift of the landward side of the forearc basin and created a forearc-high, the modern Taurides. We also analyzed the influence of factors such as viscous properties of the crust and sedimentary accumulation rates. These parameters have a strong impact in the overall evolution of the margin as well as in when and whether surface uplift in the forearc-high occurs. Higher values in the viscous parameters drive older, more pronounced uplift, than lower viscosity values. Decreasing values change the shape and time-evolution of uplift, from older rounded-shaped uplift to mid-aged box-shaped uplift to absence of uplift. Large accumulation rates develop thicker basins that stabilize the margin and shift deformation towards their margins. This also induces surface uplift to take place at younger times and can lead to avoid its happening, i.e, if sediment accumulation rates are large, the subduction system needs longer times to develop the forearc-high. We conclude that the Cyprian subduction system drives mechanical accretion in Cyprus and deep-seated deformation in S Turkey, which in turn control vertical tectonic motions and topography development in the margin.

Fernández-Blanco, David; Bertotti, Giovanni; Cassola, Teodoro; Willett, Sean

2014-05-01

325

The spectra of the topography of the earth, Venus, and Mars  

NASA Astrophysics Data System (ADS)

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.

Balmino, G.

1993-06-01

326

Extreme sensitivity of the YORP effect to small-scale topography  

Microsoft Academic Search

Radiation recoil (YORP) torques are shown to be extremely sensitive to small-scale surface topography, using numerical simulations. Starting from a set of “base objects” representative of the near-Earth object population, random realizations of three types of small-scale topography are added: Gaussian surface fluctuations, craters, and boulders. For each, the expected relative errors in the spin and obliquity components of the

Thomas S. Statler

2009-01-01

327

Karst Topography: Teacher's Guide to Accompany Black and White and Color Paper Models  

NSDL National Science Digital Library

Using paper patterns, students are able to construct a model that depicts Karst topography, including typical features such as caves, limestone bedrock, sink holes, and springs. The accompanying Teachers Guide provides extensive background information about the dissolutional processes that form caves. Information is also provided about unique animals found in caves and the importance of understanding Karst topography in city planning and water resource issues.

Tau Alpha

328

Polarization phase-shifting interference microscopy for ultra-precision surface topography  

Microsoft Academic Search

Phase-shifting interference microscopy is a very important technique for precision surface topography measurement. In this paper, polarization phase-shifting interference microscopy is proposed for ultra-precision surface topography measurement. The principle of the microscopy is described and analyzed in details, a system based on the principle is constructed, and series of experimental testing are conducted on the system. The experimental results show

W. Cheng; X. Chen; L. Zhou; X. Liu

2010-01-01

329

Precise integrated topography of Dokdo, East Sea, Korea, using LIDAR DEM and Multibeam echo sounding data  

Microsoft Academic Search

In this study, We created and analyzed Precise integrated topography of Dokdo, East Sea, Korea, using land data that were collected by airborne LIDAR(Light Detection and Ranging) DEM(Digital Elevation Model) and seafloor bathymetry data by Multi-beam echo sounder. Airborne LIDAR DEM represent more detailed topography of land than other DEM data. Composition of airborne LIDAR DEM and aerial photograph produced

C. Kim; H. Joo; E. Jeong; S. Lee; H. Kim

2009-01-01

330

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

Microsoft Academic Search

Pyroclastic density currents are volcanic gas-particle flows that move along volcano flanks and over the neighboring topography. Flow particle concentration can vary between two end members, concentrated and dilute. When a pyroclastic density current interacts with an uneven topography, the flow-field variables (velocity, pressure, particle concentration) are drastically changed at the flow-substrate boundary. These changes may significantly affect the sedimentation

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

2010-01-01

331

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

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

332

Ocean and laboratory observations on waves over topography  

NASA Astrophysics Data System (ADS)

This thesis addresses the observation, analysis and dynamics of waves as being trapped, generated and focused by sloping topography. ---Shelf waves with diurnal tidal frequency off Greenland--- Tidal analysis has been carried out on current measurements at a “cross-shelf” transect off Greenland at 71 N. The diurnal tides manifest themselves mainly as a barotropic continental shelf wave, travelling southward along the shelf slope. This follows from the amplitude distribution of the diurnal tidal components and from the rotation sense of the tidal ellipses at different cross-slope locations, as calculated with simple two-dimensional models. The well organized cross-slope pattern of the velocity amplitudes is absent in observations further north near 75 N. These observations suggest that the local vanishing of the group velocity, which is caused by topography, is of importance for the existence and local amplification of these continental shelf waves with diurnal tidal frequency. ---Tidal and residual currents near the shelf break in Biscay--- Internal-wave energy in continuously stratified fluids propagates in the vertical plane, at an angle set by the wave, buoyancy and Coriolis frequencies. Repeated Acoustic Doppler Current Profiler observations on three transects, crossing the shelf edge, now directly reveal this beam-wise propagation of internal tides in the Bay of Biscay. This confirms previous suggestions based on observations sampled more sparsely in space. The present observation is made by bin-wise harmonic analysis of horizontal currents, leading to the spatial resolution of barotropic and baroclinic semi-diurnal tidal and (time-averaged) residual flows. The observed baroclinic tide compares favourably to that produced by a two-dimensional numerical model. The observations reveal details of the internal tidal beam, including its spatial amplitude distribution, presence of amphidromes and direction of phase propagation. The cross-isobath structure of the along-slope barotropic mean flow shows a localized maximum near the shelf break. Over two transects it agrees in sign and magnitude with a theoretical tidally-rectified flow. The baroclinic, cross-isobath mean flow shows a strong near-bottom downwelling flow, compensated by an on-shelf directed flow in the upper part. The along-shelf mean flow displays subsurface-intensification attributed here to frictional modification of a tidally-rectified flow that is bottom-trapped due to stratification. ---Internal wave focusing revisited--- An experiment which discussed the appearance of an internal wave attractor in a uniformly-stratified, free-surface fluid (Maas et al. 1997) is revisited. This is done in order to give a more detailed and more accurate description of the underlying focusing process. Evolution of the attractor can now be quantified. For the tank with one sloping sidewall, and for the parameter regime (density stratification, forcing frequency) studied, the inverse exponential growth rate determined at several locations in the fluid turns out to be 122 seconds always. Only the start and duration of the growth differs: away from the attractor region it appears later and is of shorter duration. Here, these features are interpreted by employing a new theoretical basis that incorporates an external forcing via a surface boundary condition (an infinitesimal barotropic seiche) and that describes the solution in terms of propagating waves.

Lam, F. P. A.

2007-01-01

333

Mapping the Topography of Mercury with MESSENGER Laser Altimetry  

NASA Technical Reports Server (NTRS)

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.

Sun, Xiaoli; Cavanaugh, John F.; Neumann, Gregory A.; Smith, David E..; Zubor, Maria T.

2012-01-01

334

Erosion of Terrestrial Rift Flank Topography: A Quantitative Study  

NASA Technical Reports Server (NTRS)

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.

Weissel, Jeffrey K.

1999-01-01

335

Localized Gravity/Topography Admittance and Correlation Spectra on Mars: Implications for Regional and Global Evolution  

NASA Technical Reports Server (NTRS)

[i] From gravity and topography data collected by the Mars Global Surveyor spacecraft we calculate gravity/topography admittances and correlations in the spectral domain and compare them to those predicted from models of lithospheric flexure. On the basis of these comparisons we estimate the thickness of the Martian elastic lithosphere (T(sub e)) required to support the observed topographic load since the time of loading. We convert T(sub e) to estimates of heat flux and thermal gradient in the lithosphere through a consideration of the response of an elastic/plastic shell. In regions of high topography on Mars (e.g., the Tharsis rise and associated shield volcanoes), the mass-sheet (small-amplitude) approximation for the calculation of gravity from topography is inadequate. A correction that accounts for finite-amplitude topography tends to increase the amplitude of the predicted gravity signal at spacecraft altitudes. Proper implementation of this correction requires the use of radii from the center of mass (collectively known as the planetary shape ) in lieu of topography referenced to a gravitational equipotential. Anomalously dense surface layers or buried excess masses are not required to explain the observed admittances for the Tharsis Montes or Olympus Mons volcanoes when this correction is applied. Derived T, values generally decrease with increasing age of the lithospheric load, in a manner consistent with a rapid decline of mantle heat flux during the Noachian and more modest rates of decline during subsequent epochs.

McGovern, Patrick J.; Solomon, Sean C.; Smith, David E.; Zuber, Maria T.; Simons, Mark; Wieczorek, Mark A.; Phillips, Roger J.; Neumann, Gregory A.; Aharonson, Oded; Head, James W.

2002-01-01

336

A Systematic Study of Topography Effect of ERT Based on 3-D Modeling and Inversion  

NASA Astrophysics Data System (ADS)

In this study, a quick method using a digital elevation model (DEM) to obtain real terrain points for generating tetrahedral mesh has been developed, based on TetGen. Then three-dimensional (3-D) forward modeling and inversion, based on the patching method of electrical resistivity tomography (ERT) and which have been compared favorably with those obtained using other software, were used to study topography effect. Asystematic research of apparent resistivity features of different topographies with pole-pole array and Wenner array has been conducted in this study. Based on that, the solutions for removing topography effect are given to the two-dimensional (2-D) survey and the 3-D survey, respectively. Comparing to the inversion result, the solution for the 2-D survey can effectively remove topography influence. A 3-D inversion algorithm incorporating topography is proposed at the same time. Two synthetic models incorporating real topography with fault and ellipse anomalies were created to test the 3-D inversion algorithm, and the results show that the relative image error is less than 30 % and the correlation coefficient is more than 90 %.

Lu, De-Bao; Zhou, Qi-You; Junejo, S. A.; Xiao, An-Lin

2014-12-01

337

Analysis of high-throughput screening reveals the effect of surface topographies on cellular morphology.  

PubMed

Surface topographies of materials considerably impact cellular behavior as they have been shown to affect cell growth, provide cell guidance, and even induce cell differentiation. Consequently, for successful application in tissue engineering, the contact interface of biomaterials needs to be optimized to induce the required cell behavior. However, a rational design of biomaterial surfaces is severely hampered because knowledge is lacking on the underlying biological mechanisms. Therefore, we previously developed a high-throughput screening device (TopoChip) that measures cell responses to large libraries of parameterized topographical material surfaces. Here, we introduce a computational analysis of high-throughput materiome data to capture the relationship between the surface topographies of materials and cellular morphology. We apply robust statistical techniques to find surface topographies that best promote a certain specified cellular response. By augmenting surface screening with data-driven modeling, we determine which properties of the surface topographies influence the morphological properties of the cells. With this information, we build models that predict the cellular response to surface topographies that have not yet been measured. We analyze cellular morphology on 2176 surfaces, and find that the surface topography significantly affects various cellular properties, including the roundness and size of the nucleus, as well as the perimeter and orientation of the cells. Our learned models capture and accurately predict these relationships and reveal a spectrum of topographies that induce various levels of cellular morphologies. Taken together, this novel approach of high-throughput screening of materials and subsequent analysis opens up possibilities for a rational design of biomaterial surfaces. PMID:25554402

Hulsman, Marc; Hulshof, Frits; Unadkat, Hemant; Papenburg, Bernke J; Stamatialis, Dimitrios F; Truckenmüller, Roman; van Blitterswijk, Clemens; de Boer, Jan; Reinders, Marcel J T

2015-03-01

338

Rheology of continents and counterintuitive 3D features of the dynamic topography. (Invited)  

NASA Astrophysics Data System (ADS)

Dynamic topography is a key observable signature of the Earth's mantle convection, which is a major driving force of plate tectonics. In general view, it reflects mantle flow patterns, and hence is supposed to correlate at different extents with seismic tomography, SKS fast orientations, geodetic velocity fields and geoid anomalies. However, identification of dynamic topography had no systematic success, specifically in continents. Hence, it has been argued 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 had to be explored in 3D, which has been so far an impossible challenge due to the limited resolution and simplified representation of the lithosphere in the existing 3D models. We here present new unprecedentedly high resolution 3D experiments incorporating realistic stratified lithosphere. The results reveal strikingly disconcordant, counterintuitive features of the dynamic topography, going far beyond the inferences from previous models. In particular, weak anisotropic tectonic stress field may result 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. These 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 in tectonic-scale deformation.

Burov, E. B.; Gerya, T.

2013-12-01

339

The Laser Vegetation Imaging Sensor (LVIS): An Airborne Laser Altimeter for Mapping Vegetation and Topography  

NASA Technical Reports Server (NTRS)

The Laser Vegetation Imaging Sensor (LVIS) is an airborne laser altimeter designed to quickly and extensively map surface topography as well as the relative heights of other reflecting surfaces within the laser footprint. Since 1997, this instrument has primarily been used as the airborne simulator for the Vegetation Canopy Lidar (VCL) mission, a spaceborne mission designed to measure tree height, vertical structure and ground topography (including sub-canopy topography). LVIS is capable of operating from 500 m to 10 km above ground level with footprint sizes from 1 to 60 m. Laser footprints can be randomly spaced within the 7 degree telescope field-of-view, constrained only by the operating frequency of the ND:YAG Q-switched laser (500 Hz). A significant innovation of the LVIS altimeter is that all ranging, waveform recording, and range gating are performed using a single digitizer, clock base, and detector. A portion of the outgoing laser pulse is fiber-optically fed into the detector used to collect the return signal and this entire time history of the outgoing and return pulses is digitized at 500 Msamp/sec. The ground return is then located using software digital signal processing, even in the presence of visibly opaque clouds. The surface height distribution of all reflecting surfaces within the laser footprint can be determined, for example, tree height and ground elevation. To date, the LVIS system has been used to monitor topographic change at Long Valley caldera, CA, as part of NASA's Topography and Surface Change program, and to map tree structure and sub-canopy topography at the La Selva Biological Research Station in Costa Rica, as part of the pre-launch calibration activities for the VCL mission. We present results that show the laser altimeter consistently and accurately maps surface topography, including sub-canopy topography, and vegetation height and structure. These results confirm the measurement concept of VCL and highlight the benefits of airborne prototypes of spaceborne instruments.

Bryan, J.; Rabine, David L.

1998-01-01

340

A consistent data set of Antarctic ice sheet topography, cavity geometry, and global bathymetry  

NASA Astrophysics Data System (ADS)

Sub-ice shelf circulation and freezing/melting rates in ocean general circulation models depend critically on an accurate and consistent representation of cavity geometry. Existing global or pan-Antarctic topography data sets have turned out to contain various inconsistencies and inaccuracies. The goal of this work is to compile independent regional surveys and maps into a global data set. We use the S-2004 global 1-min bathymetry as the backbone and add an improved version of the BEDMAP topography (ALBMAP bedrock topography) for an area that roughly coincides with the Antarctic continental shelf. The position of the merging line is individually chosen in different sectors in order to capture the best of both data sets. High-resolution gridded data for ice shelf topography and cavity geometry of the Amery, Fimbul, Filchner-Ronne, Larsen C and George VI Ice Shelves, and for Pine Island Glacier are carefully merged into the ambient ice and ocean topographies. Multibeam survey data for bathymetry in the former Larsen B cavity and the southeastern Bellingshausen Sea have been obtained from the data centers of Alfred Wegener Institute (AWI), British Antarctic Survey (BAS) and Lamont-Doherty Earth Observatory (LDEO), gridded, and blended into the existing bathymetry map. The resulting global 1-min Refined Topography data set (RTopo-1) contains self-consistent maps for upper and lower ice surface heights, bedrock topography, and surface type (open ocean, grounded ice, floating ice, bare land surface). The data set is available in NetCDF format from the PANGAEA database at doi:10.1594/pangaea.741917.

Timmermann, R.; Le Brocq, A.; Deen, T.; Domack, E.; Dutrieux, P.; Galton-Fenzi, B.; Hellmer, H.; Humbert, A.; Jansen, D.; Jenkins, A.; Lambrecht, A.; Makinson, K.; Niederjasper, F.; Nitsche, F.; Nøst, O. A.; Smedsrud, L. H.; Smith, W. H. F.

2010-12-01

341

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

NASA Astrophysics Data System (ADS)

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 results naturally depend on the ratio between the mantle and the lithospheric thicknesses. We show that, in the case of Mars, it is not possible to approximate viscoelastic topographies generated by a stable plume using the elastic filtering of viscous dynamic topographies.

Dumoulin, Caroline; ?adek, Ond?ej; Choblet, Gaël

2013-04-01

342

Impacts of Topography and Land Cover Changes on Regional Climate Over the Eastern Mediterranean  

NASA Astrophysics Data System (ADS)

The influence of the topography (mountain ranges, lowlands etc) on Mediterranean climate leads to different climatic types. There are extensive south to north range of mountains (Italian and Balkan Peninsula), as well as smaller mountainous regions with east - west orientation that separate the warm southern region from the cooler north regions. In addition, the wide indentation of Mediterranean coasts (Aegean, Adriatic etc), provide additional moisture sources. During winter season, heavy precipitation assists vegetation growth of Mediterranean forests and woodlands, whereas during summer, absence of precipitation and severe heat waves result to arid and semiarid vegetation. For that reason, it was quite interesting to track the changes that may occur in the climate of the Mediterranean region due to changes in topography and land use. The main objective of the study is the assessment of the impacts of topography and land cover changes on regional climate over the eastern Mediterranean. The examined regional climate model is RegCM4.3. Its spatial resolution is 25x25km and for the future projections the model is using the A1B SRES emission scenario. For the purposes of this study, different simulations were performed with changes in topography and land cover for the time period 1981-2000. The different simulated data were compared in order to examine the modifications that occur from the topography and land cover changes in extreme events and atmospheric circulation in the domain of study.

Velikou, Kondylia; Anagnostopoulou, Christina; Tolika, Konstantia

2014-05-01

343

Three-dimensional finite difference viscoelastic wave modelling including surface topography  

NASA Astrophysics Data System (ADS)

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 seismograms of the wavefield show clear conversion from P to Rg (short-period fundamental-mode Rayleigh) waves in areas of rough topography, which is consistent with numerous observations. By parallelization on fast supercomputers, it is possible to model higher frequencies and/or larger areas than before.

Hestholm, Stig

1999-12-01

344

The Importance of Basal Topography for Greenland Ice Sheet Margin Hydrology  

NASA Astrophysics Data System (ADS)

Nearly half of the Greenland ice sheet's total mass loss is controlled by surface mass balance, primarily driven by meltwater runoff exiting at its margin via supra-, en-, and sub-glacial drainage networks into fjords and pro-glacial lakes and rivers. Despite the importance of meltwater runoff, Greenland's hydrologic drainage patterns are not well understood. This is partly due to a scarcity of ice sheet meltwater runoff observations and detailed information about supra- and sub-glacial topography, which are responsible for dictating runoff flow patterns. However, such data are available locally in southwest Greenland for the Akuliarusiarsuup Kuua (AK) River watershed. In this study, NASA IceBridge supra-glacial (Airborne Topographic Mapper (ATM)) and sub-glacial (Multichannel Coherent Radar Depth Sounder (MCoRDS)) topography and in situ hydrologic data from 2009-2012 are used to study three nested riverine systems within the AK River watershed ranging from 8 to 101 km2. Examination of relationships between drainage patterns modeled from topographic data and actual ice sheet runoff losses provide insight into drainage basin delineation accuracy, scale-dependency, and surface and sub-glacial topography controls on ice sheet margin hydrology. Finally, an assessment is made to determine the importance of incorporating basal topography within meltwater runoff models versus surface topography alone.

Moustafa, S.; Rennermalm, A. K.; Smith, L. C.; Pitcher, L. H.; Chu, V. W.

2012-12-01

345

On the residual isostatic topography effect in the gravimetric Moho determination  

NASA Astrophysics Data System (ADS)

In classical isostatic models, a uniform crustal density is typically assumed, while disregarding the crustal density heterogeneities. This assumption, however, yields large errors in the Moho geometry determined from gravity data, because the actual topography is not fully isostatically compensated. Moreover, the sub-crustal density structures and additional geodynamic processes contribute to the overall isostatic balance. In this study we investigate the effects of unmodelled density structures and geodynamic processes on the gravity anomaly and the Moho geometry. For this purpose, we define the residual isostatic topography as the difference between actual topography and isostatic topography, which is computed based on utilizing the Vening Meinesz-Moritz isostatic theory. We show that the isostatic gravity bias due to disagreement between the actual and isostatically compensated topography varies between -382 and 596 mGal. This gravity bias corresponds to the Moho correction term of -16 to 25 km. Numerical results reveal that the application of this Moho correction to the gravimetrically determined Moho depths significantly improves the RMS fit of our result with some published global seismic and gravimetric Moho models. We also demonstrate that the isostatic equilibrium at long-to-medium wavelengths (up to degree of about 40) is mainly controlled by a variable Moho depth, while the topographic mass balance at a higher-frequency spectrum is mainly attained by a variable crustal density.

Bagherbandi, Mohammad; Tenzer, Robert; Sjöberg, Lars E.; Abrehdary, Majid

2015-01-01

346

Gravity-driven flows of viscous liquids over two-dimensional topographies  

NASA Astrophysics Data System (ADS)

Using phase-stepped interferometry, we have measured full two-dimensional maps of the free-surface shape of a thin liquid film of water flowing over an inclined plate with topography. The measurement technique allows us to image automatically the shape of the free surface in a single field of view of about 2.4 by 1.8 mm, with a lateral resolution of 3.1 [mu]m and a height resolution of 0.3 [mu]m. By imaging neighbouring regions and combining them, complete two-dimensional free-surface profiles of gravity-driven liquid films with a thickness ranging between 80 and 120 [mu]m are measured, over step, trench, rectangular and square topographies with depths of 10 and 20 [mu]m, and lateral dimensions of the order of 1 to several mm. The experimental results for both one- and two-dimensional flows are found to be in good agreement with existing models, including a recent two-dimensional Green's function of the linearized problem by Hayes et al. This extends the applicability of simple models to cases with a high value of topography steepness and low-viscosity liquids as in our experiments. A corollary of the agreement with the linear two-dimensional model is that our experimental results behave linearly, a convenient property that allows the free-surface response to complex topographies to be worked out from knowledge of the response to an elementary topography like a square.

Decré, Michel M. J.; Baret, Jean-Christophe

2003-07-01

347

Flow of evaporating, gravity-driven thin liquid films over topography  

NASA Astrophysics Data System (ADS)

The effect of topography on the free surface and solvent concentration profiles of an evaporating thin film of liquid flowing down an inclined plane is considered. The liquid is assumed to be composed of a resin dissolved in a volatile solvent with the associated solvent concentration equation derived on the basis of the well-mixed approximation. The dynamics of the film is formulated as a lubrication approximation and the effect of a composition-dependent viscosity is included in the model. The resulting time-dependent, nonlinear, coupled set of governing equations is solved using a full approximation storage multigrid method. The approach is first validated against a closed-form analytical solution for the case of a gravity-driven, evaporating thin film flowing down a flat substrate. Analysis of the results for a range of topography shapes reveal that although a full-width, spanwise topography such as a step-up or a step-down does not affect the composition of the film, the same is no longer true for the case of localized topography, such as a peak or a trough, for which clear nonuniformities of the solvent concentration profile can be observed in the wake of the topography.

Gaskell, P. H.; Jimack, P. K.; Sellier, M.; Thompson, H. M.

2006-01-01

348

Molecular response of Escherichia coli adhering onto nanoscale topography  

PubMed Central

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

2012-01-01

349

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

NASA Astrophysics Data System (ADS)

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

Adcroft, Alistair

2013-07-01

350

Various interaction patterns of free-surface flow over multiple bumps at the bottom topography  

NASA Astrophysics Data System (ADS)

The free-surface flow generated by multiple bumps at the bottom topography in a rectangular channel was considered, in the framework of the forced Korteweg-de Vries (fKdV) equation. The fKdV equationwill be solved numerically using pseudo-spectral method as an analytical solution could not be obtained due to the presence of forcing term and broken symmetry. Various interaction patterns of solitary waves with certain parameter regimes were observed and presented in various graphical forms. Interesting interaction patterns of the collision between uniformly forced solitons will provide us with a better understanding of the hindrance caused by multiple bumps at the uneven bottom topography and it will have a high impact on the water flow in a rectangular channel with uneven bottom topography.

Kee, B. H.; Ong, C. T.; Tiong, W. K.

2014-12-01

351

Effect of Micro- and Nanoscale Topography on the Adhesion of Bacterial Cells to Solid Surfaces  

PubMed Central

Attachment and biofilm formation by bacterial pathogens on surfaces in natural, industrial, and hospital settings lead to infections and illnesses and even death. Minimizing bacterial attachment to surfaces using controlled topography could reduce the spreading of pathogens and, thus, the incidence of illnesses and subsequent human and financial losses. In this context, the attachment of key microorganisms, including Escherichia coli, Listeria innocua, and Pseudomonas fluorescens, to silica and alumina surfaces with micron and nanoscale topography was investigated. The results suggest that orientation of the attached cells occurs preferentially such as to maximize their contact area with the surface. Moreover, the bacterial cells exhibited different morphologies, including different number and size of cellular appendages, depending on the topographical details of the surface to which they attached. This suggests that bacteria may utilize different mechanisms of attachment in response to surface topography. These results are important for the design of novel microbe-repellant materials. PMID:23416997

Hsu, Lillian C.; Fang, Jean; Borca-Tasciuc, Diana A.; Worobo, Randy W.

2013-01-01

352

Small-Scale Gopher and Plant Activity Organizes a Simulated Landscape Into Mound-Pool Topography  

NASA Astrophysics Data System (ADS)

The Mima-mound-and-vernal-pool topography of California is rich in endemic species, but we do not know how this unusual environment is created or maintained. Fossorial rodents have been observed to move soil upwards at annual rates sufficient to maintain the mounds despite erosion, but there is no tested explanation of this behavior. We propose that the mounds are an emergent effect of small-scale (10 cm, 1 day) interactions between topography, hydrology, plant growth, and rodent burrowing. A cellular automata simulation of these both generates and maintains mound-pool topography with minimal dependence on initial conditions, and can also describe mound morphogenesis on slopes, where observed mound geometry is distinct from that on level ground.

Lewis, C. P.

2011-12-01

353

Calibration of the scales of areal surface topography measuring instruments: part 3. Resolution  

NASA Astrophysics Data System (ADS)

Calibration of the scales of areal surface topography measuring instruments requires testing of the resolution. Several designs of artefact that allow testing of the resolution of such instruments are currently available; however, analysis methods need to be developed to provide comparable results. A novel method for determining the lateral resolution of areal surface topography measuring instruments is presented. The method uses a type ASP (star-shaped) material measure. To demonstrate the validity of the method, the resolution of a phase shifting interferometer was determined based on the ISO definition of the lateral period limit. Using the proposed method, the type ASP material measure, which is often used to judge qualitatively an instrument's resolution, can be used to quantitatively estimate the resolution of instruments using the topography data.

Giusca, Claudiu L.; Leach, Richard K.

2013-10-01

354

Development of ballistics identification—from image comparison to topography measurement in surface metrology  

NASA Astrophysics Data System (ADS)

Fired bullets and ejected cartridge cases have unique ballistics signatures left by the firearm. By analyzing the ballistics signatures, forensic examiners can trace these bullets and cartridge cases to the firearm used in a crime scene. Current automated ballistics identification systems are primarily based on image comparisons using optical microscopy. The correlation accuracy depends on image quality which is largely affected by lighting conditions. Because ballistics signatures are geometrical micro-topographies by nature, direct measurement and correlation of the surface topography is being investigated for ballistics identification. A Two-dimensional and Three-dimensional Topography Measurement and Correlation System was developed at the National Institute of Standards and Technology for certification of Standard Reference Material 2460/2461 bullets and cartridge cases. Based on this system, a prototype system for bullet signature measurement and correlation has been developed for bullet signature identifications, and has demonstrated superior correlation results.

Song, J.; Chu, W.; Vorburger, T. V.; Thompson, R.; Renegar, T. B.; Zheng, A.; Yen, J.; Silver, R.; Ols, M.

2012-05-01

355

Stationary Wave Activity Simulated by the NASA Ames MGCM Incorporating New MOLA Topography Data  

NASA Technical Reports Server (NTRS)

Annual simulations of Mars' atmosphere have been conducted with the NASA Ames Mars General Circulation Model (MGCM) using the newly-acquired MOLA topography data. The data is provided at 1 x 1 deg resolution, and is used by the MGCM at 7.5 x 9 deg resolution. The vertical domain in the simulations reported here extends to around 80 km. Simulated stationary wave activity is examined in each hemisphere as a function of season (at every 30 deg of Ls), dust loading (dust visible opacities of 0.3, 1, and 3), and topography (comparing results with MOLA vs. Smith-Zuber topography). Additional information is contained in the original extended abstract.

Bridger, A. F. C.; Hollingsworth, J. L.; Haberle, R. M.; Schaeffer, J.

1999-01-01

356

Mantle Flow, Dynamic Topography and Rift-Flank Uplift of Arabia  

NASA Astrophysics Data System (ADS)

The Red Sea is flanked by highlands. To the east, the Arabian platform is broadly tilted along an axis that runs parallel to the sea, and the long tail of high topography has been described as a classic example of `rift-flank uplift' [Wernicke, 1985]. A suite of thermal and mechanical effects have been invoked to derive generic mechanisms for flank uplift and these have been applied, with varying levels of success, to the Arabian case. We propose that dynamic topography supported by large scale mantle flow beneath the Africa-Arabia system contributes significantly to the observed pattern of Arabian rift-flank uplift. Seismic tomographic images indicate the existence of large scale (anomalously slow) heterogeneity originating from the deep mantle under southern Africa and, apparently, connecting to more shallow structure beneath the East African Rift system and the Arabian plate. We predict Arabian topography driven by viscous stresses associated with this buoyant megastructure. We first convert velocity anomalies given by the seismic S-wave model S20RTS [Ritsema et al., 1999] to density anomalies using standard scaling profiles, and then input these into a 2-D mantle convection model. Normal stresses derived from the flow models are then used to compute associated profiles of surface (`dynamic') topography. These profiles reconcile the observed topography of the Arabian platform and they provide an explanation for the distinct geometry of rift-flank uplift across the two sides of the Red Sea. Our calculations do not preclude a contribution to topography from previously described thermal and/or mechanical effects; however, they indicate that future analyses of rift-flank uplift should consider the potential contribution from large scale mantle flow.

Daradich, A. L.; Mitrovica, J. X.; Pysklywec, R. N.; Willett, S. D.

2002-12-01

357

A Generalized Subsurface Flow Parameterization Considering Subgrid Spatial Variability of Recharge and Topography  

SciTech Connect

Subsurface flow is an important hydrologic process and a key component of the water budget, especially in humid regions. In this study, a new subsurface flow formulation is developed that incorporates spatial variability of both topography and recharge. It is shown through theoretical derivation and case studies that the power law and exponential subsurface flow parameterizations and the parameterization proposed by Woods et al.[1997] are all special cases of the new formulation. The subsurface flows calculated using the new formulation compare well with values derived from observations at the Tulpehocken Creek and Walnut Creek watersheds. Sensitivity studies show that when the spatial variability of topography or recharge, or both is increased, the subsurface flows increase at the two aforementioned sites and the Maimai hillslope. This is likely due to enhancement of interactions between the groundwater table and the land surface that reduce the flow path. An important conclusion of this study is that the spatial variability of recharge alone, and/or in combination with the spatial variability of topography can substantially alter the behaviors of subsurface flows. This suggests that in macroscale hydrologic models or land surface models, subgrid variations of recharge and topography can make significant contributions to the grid mean subsurface flow and must be accounted for in regions with large surface heterogeneity. This is particularly true for regions with humid climate and relatively shallow groundwater table where the combined impacts of spatial variability of recharge and topography are shown to be more important. For regions with arid climate and relatively deep groundwater table, simpler formulations, especially the power law, for subsurface flow can work well, and the impacts of subgrid variations of recharge and topography may be ignored.

Huang, Maoyi; Liang, Xu; Leung, Lai R.

2008-12-05

358

Topography-Dependent Eikonal Traveltime Tomography for Upper Crustal Structure Beneath an Irregular Surface  

NASA Astrophysics Data System (ADS)

Seismic modeling of the crust with nonflat topography can be made by first-arrival traveltime tomography, which faces the challenge of an irregular free surface. A feasible way to deal with this problem consists of expanding the physical space by overlapping a low velocity layer above the irregular surface in order to have a flat topography, besides using the classical eikonal equation solver for traveltime computation. However, the undesirable consequences of this method include seismic ray deviations due to the transition from an irregular surface that is the free boundary to an inner discontinuity lying in the expanded computational space. An alternative solution, called irregular surface flattening, which involves the transformation between curvilinear and Cartesian coordinate systems, has been recently proposed through the formulation of the topography-dependent eikonal equation (TDEE) and a new solver for forward modeling of traveltimes. Based on the solution of this equation, we present topography-dependent eikonal traveltime tomography (hereafter TDETT) for seismic modeling of the upper crust. First-arrival traveltimes are calculated using the TDEE solver and the raypaths with the minimum traveltime that can be found by following the steepest traveltime gradient from the receiver to the source. By solving an algebraic equation system that connects the slowness perturbations with the already determined traveltimes, these variables can be obtained making use of the back-projection algorithm. This working scheme is evaluated through three numerical examples with different topographic complexities that are conducted from synthetic data and a fourth example with somewhat more complicated topography and real data acquired in northeastern Tibet. The comparison of the results obtained by both methods, i.e., physical space expansion above the irregular surface and irregular surface flattening, fully validates the tomography scheme that is proposed to construct seismic velocity models with nonflat topography.

Ma, Ting; Zhang, Zhongjie

2014-11-01

359

Dependence of Eemian Greenland temperature reconstructions on the ice sheet topography  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

360

Dependence of Eemian Greenland temperature reconstructions on the ice sheet topography  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

361

Sentinel-3 Surface Topography Mission: Payload, Data Products and Cal/Val Preparation  

NASA Astrophysics Data System (ADS)

Sentinel-3 is an Earth observation satellite mission designed for GMES to ensure the long-term collection of high-quality measurements delivered in an operational manner to GMES ocean, land, atmospheric, emergency and security services. Primary sentinel-3 topography mission measurement requirements have been derived from GMES user needs as follows: • Sea surface topography (SSH), significant wave height (Hs) and surface wind speed derived over the global ocean to an equivalent accuracy and precision as that presently achieved by ENVISAT Radar Altimeter-2 (RA-2). • Enhanced surface topography measurements in the coastal zone, sea ice regions and over inland rivers, their tributaries and lakes. To address the above requirements, the Sentinel-3 Topography payload will carry a Synthetic Aperture Radar Altimeter (SRAL) instrument, a passive microwave radiometer (MWR) a GPS receiver and laser retro-reflector for precise orbit determination providing continuing the legacy of ENVISAT RA-2 and Cryosat. Three level of timeliness are defined within GMES for the S-3 Topography mission: • NRT products, delivered to the users in less than 3 hours after acquisition of data by the sensor, • Short time critical (STC) products, delivered to the users in less than 48 hours after the acquisition and, • Non-time critical (NTC) products delivered not later than 1 month after acquisition or from long-term archives. The Sentinel-3 topography data products will provide continuity of ENVISAT type measurement capability in Europe to determine sea, ice and land surface topography measurements with high accuracy, timely delivery and in a sustained operational manner for GMES users. The Sentinel-3 data will also provide fundamental inputs to a variety of value-adding downstream services for industry, government agencies, commercial users, service providers and appropriate regulatory authorities. The Calibration and Validation of the Sentinel-3 topography products will nominally rely on the cross-comparison with the ESA Envisat Altimetry mission and will be a significant challenge due to the stringent S-3 mission measurement requirements and their safeguarding all over the mission lifetime.

Féménias, P.; Rebhan, H.; Donlon, C.; Buongiorno, A.; Mavrocordatos, C.

2012-04-01

362

P300 latency, but not amplitude or topography, distinguishes between true and false recognition.  

PubMed

Two experiments are described in which the P300 component of the event-related potential was recorded during a modification of the Deese-Roediger-McDermott false-memory paradigm. P300 amplitudes and topographies were evaluated in both true recognition of previously presented (studied) words and in false recognition of associatively related, never presented (critical lure) words. P300 topography and amplitude did not appear to differ between true and false recognition. However, false recognition of critical lures produced substantially shorter P300 latencies than did the true recognition of studied words. PMID:11294437

Miller, A R; Baratta, C; Wynveen, C; Rosenfeld, J P

2001-03-01

363

Preliminary Investigation of EarthScope EARS Derived MOHO Topography and Large Scale Faye Gravity Anomaly  

NASA Astrophysics Data System (ADS)

This is a preliminary investigation using the EarthScope EARS receiver functions in combination with the Faye gravity anomaly. This includes both qualitative and quantitative comparison of the large scale Faye anomaly with an expected 3D geology interpretation for the southern mid-continent U.S.A. The 3D geology interpretation consists of expected 3D topographies based on National Elevation Data, published formation elevations, measured and published basement topography with geology, and the expected MOHO topography calculated using the EARS estimated crustal thickness. The EARS automated receiver functions provides a large data set of automatically generated receiver functions and models of bulk crustal properties. These bulk crustal properties include crustal thickness, and Vp/Vs given an assumed Vp. The results from this automatic determination can be evaluated through the H-K stacking, and are often a good method to identify where there may be complex structure or poor quality data. Some a priori information is used to constrain the EARS crustal model. The observed Faye gravity anomaly is calculated using the observed gravity value at their observation location from the PACES gravity database and their extracted elevation from the national elevation data set. Then the expected Faye gravity is modeled using the expected 3D geology interpretation. The observed and modeled Faye gravity, along with the expected 3D geologic interpretation with its topographies and geology and their expected uncertainties are used in a simple 3D density inversion to evaluate the consistency of the estimated with the expected crust / MOHO interface. Areas with complex crustal geology and or inconsistent EARS data are identified as areas of higher uncertainty and require further study. Even areas with agreement between the expected MOHO topography and the Faye anomaly have interesting geology implications. For example: in central Oklahoma the 14 km deep Anadarko basin has a positive Faye anomaly associated with it without surface topography at the same location there is a positive qualitative correlation with the EARS derived MOHO topography. The Faye gravity and MOHO topography may imply an extension of the Mid-Continent Rift through Kansas to the Southern Oklahoma Aulacogen and possibly further south and requires further investigation.

Crain, K.; Holland, A. A.

2013-12-01

364

Frictional and bone ingrowth properties of engineered surface topographies produced by electron beam technology  

Microsoft Academic Search

Background  Electron beam melting (E-beam) is a new technology to produce 3-dimensional surface topographies for cementless orthopedic\\u000a implants.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  The friction coefficients of two newly developed E-beam produced surface topographies were in vitro compared with sandblasted\\u000a E-beam and titanium plasma sprayed controls. Bone ingrowth (direct bone–implant contact) was determined by implanting the\\u000a samples in the femoral condyles of 6 goats for a

J. Elizabeth Biemond; René Aquarius; Nico Verdonschot; Pieter Buma

2011-01-01

365

Sea-surface topography of the Gulf of Mexico, based on ship drift  

E-print Network

SEA-SURFACE TOPOGRAPHY OF THE GULF OF MEXICO, BASED ON SHIP DRIFT A Thesis JOHNNIE BURDETTE LINN III Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER QF SCIENCE May... 1975 Major Subject: Oceanography SEA-SURFACE TOPOGRAPHY OF THE GULF OF MEXICO, BASED ON SHIP DRIFT A Thesi. s by JOHNNIE BURDETTE LINN III Approved as to style and content by: ( airman of Committee) (Head of Department) (Memb er) Xl~ VJ !'i...

Linn, Johnnie Burdette

1975-01-01

366

Velocity field reconstruction in gravity-driven flow over unknown topography  

NASA Astrophysics Data System (ADS)

A numerical method for reconstructing the velocity field of a viscous liquid flowing over unknown topography is presented. For a given fluid this procedure allows one to determine the velocity field as well as the topographic structure from the free-surface shape only. First, we confirm the results with previous computations in the thin-film limit and then generalize the numerical solution to arbitrary film thicknesses and focus on the velocity field. It is documented that even smoothly corrugated free-surface shapes require strongly undulated topographies to maintain the flow structure. Finally, we discuss details of the implementation in applications, solvability in general, and sensitivity of the solution.

Heining, C.

2011-03-01

367

Effects of digital elevation model map scale and data resolution on a topography-based watershed model  

Microsoft Academic Search

The effects of digital elevation model (DEM) map scale and data resolution on watershed model predictions of hydrologic characteristics were determined for TOPMODEL, a topography-based watershed model. The effects of topography on watershed hydrology are represented in TOPMODEL as the distribution of ln (a\\/tan B), where ln is the Napierian logarithm, a is the upslope area per unit contour length,

David M. Wolock; Curtis V. Price

1994-01-01

368

Internal wave and boundary current generation by tidal flow over topography Amadeus Dettner, Harry L. Swinney, and M. S. Paoletti  

E-print Network

Internal wave and boundary current generation by tidal flow over topography Amadeus Dettner, Harry turbulence and small-scale internal waves above deep-ocean topography Phys. Fluids 25, 106604 (2013); 10.1063/1.4826888 Topographically induced internal solitary waves in a pycnocline: Secondary generation and selection criteria Phys

Texas at Austin. University of

369

Effects of Realistic Surface Topography on Seismic Ground Motion in the Yangminshan Region of Taiwan Based Upon  

E-print Network

-element method to simulate three-dimensional (3D) seismic-wave propagation in the Yangminshan region in Taiwan, incorporating the effects of realistic topography. A smoothed topographic map is employed beneath the modelEffects of Realistic Surface Topography on Seismic Ground Motion in the Yangminshan Region

Komatitsch, Dimitri

370

Impact of Hillslope-Scale Organization of Topography, Soil Moisture, Soil Temperature, and Vegetation on Modeling Surface Microwave Radiation Emission  

Microsoft Academic Search

Microwave radiometry will emerge as an important tool for global remote sensing of near-surface soil moisture in the coming decade. In this modeling study, we find that hillslope-scale topography (tens of meters) influences microwave brightness temperatures in a way that produces bias at coarser scales (kilometers). The physics underlying soil moisture remote sensing suggests that the effects of topography on

Alejandro N. Flores; Valeriy Y. Ivanov; Dara Entekhabi; Rafael L. Bras

2009-01-01

371

Small?footprint, waveform?resolving lidar estimation of submerged and sub?canopy topography in coastal environments  

Microsoft Academic Search

The experimental advanced airborne research lidar (EAARL) is an airborne lidar instrument designed to map near?shore submerged topography and adjacent land elevations simultaneously. This study evaluated data acquired by the EAARL system in February 2003 and March 2004 along the margins of Tampa Bay, Florida, USA, to map bare?earth elevations under a variety of vegetation types and submerged topography in

A. Nayegandhi; J. C. Brock; C. W. Wright

2009-01-01

372

Functions of Maladaptive Behavior in Intellectual and Developmental Disabilities: Behavior Categories and Topographies  

ERIC Educational Resources Information Center

Research has shown that different maladaptive behavior categories may be maintained by different contingencies. We examined whether behavior categories or behavior topographies determine functional properties. The "Questions about Behavioral Function" with its five subscales ("Attention", "Escape", "Nonsocial", "Physical", and "Tangible") was…

Rojahn, Johannes; Zaja, Rebecca H.; Turygin, Nicole; Moore, Linda; van Ingen, Daniel J.

2012-01-01

373

Coastal topography–Northeast Atlantic coast, post-hurricane Sandy, 2012  

USGS Publications Warehouse

This Data Series contains lidar-derived bare-earth (BE) topography, dune elevations, and mean-high-water shoreline position datasets for most sandy beaches for Fire Island, New York, and from Cape Henlopen, Delaware to Cape Lookout, North Carolina. The data were acquired post-Hurricane Sandy, which made landfall as an extratropical cyclone on October 29, 2012.

Stockdon, Hilary F.; Doran, Kara S.; Sopkin, Kristin L.; Smith, Kathryn E.L.; Fredericks, Xan

2013-01-01

374

Very high-frequency digital ultrasound evaluation of topography-wavefront-guided repair after radial keratotomy.  

PubMed

We report a topography-wavefront-guided repair procedure in a patient with a decentered optical zone and significant higher-order aberrations (HOAs) following radial keratotomy 14 years previously. The CRS-Master custom ablation software was used to generate a topography-wavefront-guided ablation profile based on Atlas front corneal surface topography data, and the MEL 80 excimer laser was used to treat the patient. Very high-frequency digital ultrasound scanning (Artemis) was performed before and after surgery to measure epithelial and stromal thickness changes to evaluate the anatomical congruity of the planned and achieved irregular ablation. Nine months postoperatively, the optical zone centration was topographically improved and HOAs were significantly lower, with a 90% reduction in spherical aberration. The stromal thickness change map demonstrated that the profile of stromal tissue removed matched the irregular ablation profile. However, the measured stromal thickness change at the maximum point was 33% higher than the predicted ablation depth. The epithelial thickness change measured in this case indicates that topography-guided treatments could be improved by taking epithelial thickness changes into account. PMID:21333882

Reinstein, Dan Z; Archer, Timothy J; Gobbe, Marine

2011-03-01

375

Polymers with hydro-responsive topography identified using high throughput AFM of an acrylate microarray†  

PubMed Central

Atomic force microscopy has been applied to an acrylate polymer microarray to achieve a full topographic characterisation. This process discovered a small number of hydro-responsive materials created from monomers with disparate hydrophilicities that show reversibility between pitted and protruding nanoscale topographies. PMID:23259005

Hook, Andrew L.; Yang, Jing; Chen, Xinyong; Roberts, Clive J.; Mei, Ying; Anderson, Daniel G.; Langer, Robert; Alexander, Morgan R.; Davies, Martyn C.

2012-01-01

376

A novel approach to characterizing the surface topography of niobium superconducting radio frequency (SRF) accelerator cavities  

SciTech Connect

As superconducting niobium radio-frequency (SRF) cavities approach fundamental material limits, there is increased interest in understanding the details of topographical influences on realized performance limitations. Micro- and nano-roughness are implicated in both direct geometrical field enhancements as well as complications of the composition of the 50 nm surface layer in which the super-currents typically flow. Interior surface chemical treatments such as buffered chemical polishing (BCP) and electropolishing (EP) used to remove mechanical damage leave surface topography, including pits and protrusions of varying sharpness. These may promote RF magnetic field entry, locally quenching superconductivity, so as to degrade cavity performance. A more incisive analysis of surface topography than the widely used average roughness is needed. In this study, a power spectral density (PSD) approach based on Fourier analysis of surface topography data acquired by both stylus profilometry and atomic force microscopy (AFM) is introduced to distinguish the scale-dependent smoothing effects, resulting in a novel qualitative and quantitative description of Nb surface topography. The topographical evolution of the Nb surface as a function of different steps of well-controlled EP is discussed. This study will greatly help to identify optimum EP parameter sets for controlled and reproducible surface levelling of Nb for cavity production.

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

2011-03-01

377

Adjuvant intravaginal brachytherapy for uterus didelphys with synchronous endometrial adenocarcinomas and unfavourable vaginal topography.  

PubMed

? We describe a case of uterus didelphys with synchronous endometrial cancers. ? Unfavorable post-operative disturbance of the vaginal vault topography was present. ? Hence the Institut Gustave-Roussy "moulage" IVBT technique was utilised. ? This customised technique achieved excellent mould-to-mucosa conformance. PMID:24371641

Morris, Lucinda; Stevens, Mark John; Valmadre, Susan; Martland, Judith; Lee, Tony

2012-01-01

378

Effects of grazing, topography, and precipitation on the structure of a semiarid grassland  

Microsoft Academic Search

Structural aspects of the shortgrass steppe plant community, functional groups, and species populations were examined in response to long-term heavy grazing and exclosure from grazing, contiguous wet or dry years, and an environmental gradient of topography. Of the three factors, relatively greater differences in community similarity were observed between catena positions, particularly on the ungrazed treatments. Grazing was intermediate between

Daniel G. Milchunas; William K. Lauenroth; Philip L. Chapman; Mohammad K. Kazempour

1989-01-01

379

Scaling and parameterization of clear-sky solar radiation over complex topography  

Technology Transfer Automated Retrieval System (TEKTRAN)

Solar radiation at the land surface is influenced by slope, aspect, shadows, and obstruction of the sky, all of which vary over a wide range of length scales in regions of complex topography, with important consequences for the surface energy balance. Atmospheric models, however, generally assume t...

380

Surface topography development and ion mixing in the study of depth profiling of multilayered structures  

Microsoft Academic Search

The depth profiling in combination with sputtering of multilayered structures is considered by the proposed models. In order to emphasize the changes in the surface composition produced by the processes of surface topography development and ion mixing during profiling two different models are proposed and considered separately. The first one includes the processes of surface roughening as a result of

A. Galdikas

1999-01-01

381

Going Underground: A Field Investigation and Lab Activity on Karst Topography and Water Systems  

ERIC Educational Resources Information Center

Students learn science best with activities that mirror the way scientists work. This article describes how geologists investigate groundwater flow systems in areas of karst topography--geologic formations shaped by dissolving bedrock--and provides a way for students to replicate this research. Students also use electric current to model water…

O'Dell, Gary; Gonzalez-Espada, Wilson

2011-01-01

382

On the role of topography and wind stress on the stability of the thermohaline circulation  

E-print Network

On the role of topography and wind stress on the stability of the thermohaline circulation Neil R). Oscillations of the thermohaline circulation which involve a PHC have typical periods O(1000 years) and can of the stability of the real ocean. In a related study of the sensitivity of the thermohaline circulation

Edwards, Neil

383

On the role of topography and wind stress on the stability of the thermohaline circulation  

E-print Network

On the role of topography and wind stress on the stability of the thermohaline circulation Neil R circulation model (Bryan 1986). Oscillationsof the thermohaline circulation which involve a PHC have typical of the stability of the real ocean. In a related study of the sensitivity of the thermohaline circulation

Edwards, Neil

384

The Relationship of the MOLA Topography of Mars to the Mean Atmospheric Pressure  

NASA Technical Reports Server (NTRS)

The MOLA topography of Mars is based on a new mean radius of the planet and new equipotential surface for the areoid. The mean atmospheric pressure surface of 6.1mbars that has been used in the past as a reference level for topography does not apply to the zero level of MOLA elevations. The MOLA mean radius of the planet is 3389508 meters and the mean equatorial radius is 339600 meters. The areoid of the zero level of the MOLA altimetry is defined to be the potential surface with the same potential as the mean equatorial radius. The MOLA topography differs from the USGS digital elevation data by approximately 1.6 km, with MOLA higher. The average pressure on the MOLA reference surface for Ls =0 is approximately 5.1 mbars and has been derived from occultation data obtained from the tracking of Viking, Mariner, and MGS spacecraft and interpolated with the aid of the Ames Mars GCM. The new topography and the new occultation data are providing a more reliable relationship between elevation and surface pressure.

Smith, David E.; Zuber, Maria T.

1999-01-01

385

Scale Dependencies of Vegetation and Topography in a Mountainous Environment of Montana  

Microsoft Academic Search

This research examines the effects of spatial scale on estimating the relationship between vegetation biomass and topography within a portion of Glacier National Park, Montana. The Reflectance\\/Absorptance vegetation index, developed from processed Landsat Thematic Mapper digital data, is related to three topographic variables obtained through processed Digital Elevation Models: elevation, slope angle, and slope aspect. R values between the vegetation

Ling Bian; Stephen J. Walsh

1993-01-01

386

EAARL topography-Three Mile Creek and Mobile-Tensaw Delta, Alabama, 2010  

USGS Publications Warehouse

This DVD contains lidar-derived first-surface (FS) and bare-earth (BE) topography GIS datasets of a portion of the Mobile-Tensaw Delta region and Three Mile Creek in Alabama. These datasets were acquired on March 6, 2010.

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

2011-01-01

387

EAARL coastal topography-Assategue Island National Seashore, Maryland and Virginia, 2010  

USGS Publications Warehouse

This DVD contains lidar-derived bare-earth (BE) and first-surface (FS) topography GIS datasets of a portion of the Assateague Island National Seashore in Maryland and Virginia. These datasets were acquired on March 19 and 24, 2010.

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

2011-01-01

388

EAARL coastal topography-Northern Outer Banks, North Carolina, post-Nor'Ida, 2009  

USGS Publications Warehouse

This DVD contains lidar-derived first-surface (FS) and bare-earth (BE) topography GIS datasets of a portion of the northern Outer Banks beachface in North Carolina. These datasets were acquired post-Nor'Ida on November 27 and 29, 2009.

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

2011-01-01

389

EAARL coastal topography-Gateway National Recreation Area, New Jersey and New York, 2009  

USGS Publications Warehouse

This DVD contains lidar-derived bare-earth (BE) and first-surface (FS) topography GIS datasets of a portion of the Gateway National Recreation Area in New Jersey and New York. These datasets were acquired July 8-9, 2009.

Nayegandhi, Amar; Vivekanandan, Saisudha; Brock, John C.; Stevens, Sara; Wright, C. Wayne; Bonisteel, Jamie M.; Nagle, David B.; Yates, Xan; Klipp, Emily S.

2010-01-01

390

Scaling and parametrization of clear-sky solar radiation over complex topography  

Technology Transfer Automated Retrieval System (TEKTRAN)

Solar radiation at the land surface is influenced by slope, aspect, shadows and obstruction of the sky, all of which vary over a wide range of length scales in regions of complex topography, with important consequences for the surface energy balance. Atmospheric models, however, generally assume the...

391

Relationship between cotton yield and soil electrical conductivity, topography, and landsat imagery  

Technology Transfer Automated Retrieval System (TEKTRAN)

Understanding spatial and temporal variability in crop yield is a prerequisite to implementing site-specific management of crop inputs. Apparent soil electrical conductivity (ECa), soil brightness, and topography are easily obtained data that can explain yield variability. The objectives of this stu...

392

Evaluation of a Pre-Treatment Assessment to Select Mand Topographies for Functional Communication Training  

ERIC Educational Resources Information Center

Recent research has suggested that variables related to specific mand topographies targeted during functional communication training (FCT) can affect treatment outcomes. These include effort, novelty of mands, previous relationships with problem behavior, and preference. However, there is little extant research on procedures for identifying which…

Ringdahl, Joel E.; Falcomata, Terry S.; Christensen, Tory J.; Bass-Ringdahl, Sandie M.; Lentz, Alison; Dutt, Anuradha; Schuh-Claus, Jessica

2009-01-01

393

Interferometric aligment of the X-SAR antenna system on the space shuttle radar topography mission  

NASA Technical Reports Server (NTRS)

The on-orbit alignment of the antenna beams of both the X-band and C-band radar systems during operations of the shuttle radar topography mission/X-band synthetic aperture radar (SRTM/X-SAR)was a key requirement for achieving best interferometric performance.

Geudtner, D.; Zink, M.; Gierull, C.; Shaffer, S.

2002-01-01

394

Effects of Fluency Instruction on Selection-Based and Topography-Based Comprehension Measures  

ERIC Educational Resources Information Center

A multiple probe across participants design was used to assess the effects of an intervention package on reading fluency and section-based and topography-based comprehension tasks. Participants were three adolescents diagnosed with high functioning pervasive developmental disorders. The intervention package consisted of listen passage preview,…

Barnes, Clarissa S.; Rehfeldt, Ruth Anne

2013-01-01

395

Thickness of the Martian crust: Improved constraints from geoid-to-topography ratios  

Microsoft Academic Search

The average crustal thickness of the southern highlands of Mars was investigated by calculating geoid-to-topography ratios (GTRs) and interpreting these in terms of an Airy compensation model appropriate for a spherical planet. We show that (1) if GTRs were interpreted in terms of a Cartesian model, the recovered crustal thickness would be underestimated by a few tens of kilometers, and

Mark A. Wieczorek; Maria T. Zuber

2004-01-01

396

A Support Vector Machines Classifier to Assess the Severity of Idiopathic Scoliosis From Surface Topography  

Microsoft Academic Search

A support vector machines (SVM) classifier was used to assess the severity of idiopathic scoliosis (IS) based on surface topographic images of human backs. Scoliosis is a condition that involves abnormal lateral curvature and rotation of the spine that usually causes noticeable trunk deformities. Based on the hypothesis that combining surface topography and clinical data using a SVM would produce

Lino Ramirez; Nelson G. Durdle; V. James Raso; Doug L. Hill

2006-01-01

397

X-ray diffraction imaging (topography) of electroopticcrystals by synchrotron radiation  

NASA Technical Reports Server (NTRS)

Information of special interest to crystal growers and device physicists now available from monochromatic synchrotron diffraction imaging (topography) is reviewed. Illustrations are taken from a variety of electro-optic crystals. Aspects of the detailed understanding of crystal growth processes obtainable from carefully selected samples are described. Finally, new experimental opportunities now available for exploitation are indicated.

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

1988-01-01

398

Fast seafloor topography extraction and visualization from sparse AUV altimeter data  

Microsoft Academic Search

Most autonomous underwater vehicles (AUVs) are equipped to collect altimetry information, either from a simple altimeter for bottom avoidance, or as a product of a Doppler Velocity Log (DVL). This paper presents practical techniques for extracting and displaying coherent gridded maps of sea floor topography from such AUV altimeter data. In particular, methods for estimating and minimizing error in derived

Matthew Zucker

2005-01-01

399

Measuring the surface topography at focal adhesions using laser feedback interferometry  

Microsoft Academic Search

Reflection interference contrast microscopy of living cells has not yet fully matured. One goal would be to temporally resolve the distance between the cell and the substratum at each point over the cell surface. We have combined phase shifting laser feedback interferometry with a high numerical aperture inverted microscope in order to determine the topography of the ventral surface of

Michael Bambino; Ben Ovryn

2006-01-01

400

Large-amplitude internal wave generation in the lee of step-shaped topography  

E-print Network

1 Large-amplitude internal wave generation in the lee of step-shaped topography B. R. Sutherland University of Alberta, Edmonton, Canada. Short title: LARGE-AMPLITUDE INTERNAL WAVE GENERATION . . . #12 downstream of the base of the step, and internal waves, which propagate vertically away from the step

Sutherland, Bruce

401

From residue matching patterns to protein folding topographies: General model and bovine  

E-print Network

From residue matching patterns to protein folding topographies: General model and bovine pancreatic-grained model for protein-folding dynamics is introduced based on a discretized representation of torsional, pattern recognition, and general characteristics of protein folding kinetics. Topology here implies

Berry, R. Stephen

402

Changes in N400 topography following intensive speech language therapy for individuals with aphasia  

E-print Network

Changes in N400 topography following intensive speech language therapy for individuals with aphasia f o Article history: Accepted 23 June 2012 Available online xxxx Keywords: Aphasia ERP N400 aphasia therapy on the N400, an electrophysiological index of lexical-semantic processing. Immediately

403

Morphological decomposition of the surface topography of an internal combustion engine cylinder to characterize wear  

Microsoft Academic Search

A surface topography decomposition methodology is presented. It decomposes a surface into three elements: reference surface (waviness and form); superficial roughness (related to friction and wear); and valleys (related to lubricant circulation and reservoirs). It is applied to cylinder liners from an internal combustion V6 engine from in order to remove form and waviness components. The study of the resulting

Etienne Decencière; Dominique Jeulin

2001-01-01

404

Puffing Topography and Interpersonal Bonding Behavior Observed Among Recovering Drug Addicts Versus General Smokers  

E-print Network

Puffing Topography and Interpersonal Bonding Behavior Observed Among Recovering Drug Addicts Versus Department of Oral Biology, Indiana University School of Dentistry; 2 Fairbanks Addiction Hospital and interpersonal bonding behaviors of recovering drug addicts to that of general smokers in a natural setting

Zhou, Yaoqi

405

Surface topography analysis in high speed finish milling inclined hardened steel  

Microsoft Academic Search

The surface texture of a milled surface is an inherently important process response in finish milling. It is one of the most commonly used criteria to determine the machinability of a particular workpiece material. However, literature survey on the study of the surface topography analysis relating to the cutter path orientations when high speed finish inclined milling is scant. Previous

C. K. Toh

2004-01-01

406

3D MODEL OF GEDONGSONGO TEMPLE AND TOPOGRAPHY USING TERRESTRIAL LASER SCANNER TECHNOLOGY  

Microsoft Academic Search

The paper reports the result of measurement of the Gedongsongo temples and the surrounding topography using laser scanning technique. Gedongsongo is located in Semarang District, Middle Jawa Province, Indonesia. The research is carried out by the Geomatics Research Division of National Coordinating Agency of Surveys and Mapping (BAKOSURTANAL) is cooperation with Borobudur Heritage Conservation Office (HCO). BAKOSURTANAL has a program

Adi J. Mustafa; Fahmi Amhar

407

Computer aided Moiré topography of 3D models of set of teeth  

Microsoft Academic Search

More effective method for description of the form of a 3D object and curved surface, than shadow moiré topography and current illumination by interference modulated laser beam, was proposed. Interference modulated laser beam that illuminates reference plane screen and the object using modification of the interference pictures by means of maxima of interference fringes, enables characterization of the object by

L. Bartonek; J. Keprt

2008-01-01

408

CASTp: computed atlas of surface topography of proteins with structural and topographical mapping  

E-print Network

CASTp: computed atlas of surface topography of proteins with structural and topographical mapping://cast.engr.uic.edu) is an online tool that locates and measures pockets and voids on 3D protein structures. This new version and to obtain a comprehensive understanding of the structural basis of protein function. The 3D structure

Dai, Yang

409

POSTURE MATCHING AND ELASTIC REGISTRATION OF A MOUSE ATLAS TO SURFACE TOPOGRAPHY RANGE DATA  

E-print Network

), contours, or silhouettes that can then be used to generate a 3D representation of the animal volumePOSTURE MATCHING AND ELASTIC REGISTRATION OF A MOUSE ATLAS TO SURFACE TOPOGRAPHY RANGE DATA A. A]. These systems typically produce a height map of the animal consisting of discrete points (called range data

Leahy, Richard M.

410

Bed topography of Store Glacier, Greenland from high-resolution airborne gravity data  

NASA Astrophysics Data System (ADS)

Store Glacier is a major west Greenland outlet tidewater glacier draining an area of 30,000 square km into Uummannaq Fjord, flowing at a speed of 4.8 km per year at the terminus. The bed topography of the glacier is poorly known and the fjord bathymetry has only been partially surveyed for the first time in 2012. In this study, we present a new approach on the modeling of glacier thickness and sea floor bathymetry based on high resolution gravity constrained with other observations. In August 2012, we acquired a 250m spacing grid of free-air gravity data at a speed of 50 knots with accuracy at sub-milligal level. We constrain the 3D inversion of these gravity data with ship-borne bathymetry near the glacier front and radar-derived ice thickness on grounded ice to derive a seamless map of bed topography of grounded ice and sea floor. Comparison of the new topography with prior maps reveals vast differences. Prior bathymetry (IBCAO3) has an ice front grounded at sea level whereas observations show a depth of 550m. On grounded ice, the data reveal the subglacial topography at an unprecedented level of spatial details. We discuss the impact of the results on the modeling of the glacier flow and the understanding of its interaction with ocean thermal forcing and surface mass balance.

An, L.; Rignot, E. J.

2013-12-01

411

Scalable and Composable Implicit Solvers for Polythermal Ice Flow with Steep Topography  

E-print Network

hybrids, 2D or 3D elliptic solves Bed slope is discontinuous and of order 1. Taylor expansions no longer) Eliminate p and w from Stokes by incompressibility: 3D elliptic system for u = (u,v) -· 4ux +2vy uy +vx uzScalable and Composable Implicit Solvers for Polythermal Ice Flow with Steep Topography Jed Brown1

Brown, Jed

412

The Approach of Dynamic Topography Maps Reconstruction By Local Spline-approximation  

Microsoft Academic Search

There are a lot of methods to process dynamic topography maps based on satellite altimetry data. In general, these methods are using Topex\\/Poseidon data, because of high accuracy of it. Some methods are used to enhance ERS altimetry data by data from Topex\\/Poseidon. These methods are based on global minimization of Topex- Poseidon - ERS dual crossover differences. However, in

V. Kunitsyn; A. Romanov

2002-01-01

413

City-wide relationships between green spaces, urban land use and topography  

E-print Network

& Olga Barbosa & Richard A. Fuller & Jamie Tratalos & Nicholas Burke & Daniel Lewis & Philip H. Warren, Norwich NR4 7TJ, UK e-mail: Richard.G.Davies@uea.ac.uk O. Barbosa Instituto de Ecología y BiodiversidadCity-wide relationships between green spaces, urban land use and topography Richard G. Davies

Queensland, University of

414

Hydrodynamic forces and surface topography: Centimeter-scale spatial variation in wave forces  

E-print Network

Hydrodynamic forces and surface topography: Centimeter-scale spatial variation in wave forces forces. The intertidal zone of wave-swept rocky shores is one of the most physically stressful (Denny et al. 2003). The high water velocities in the intertidal zone can impose large hydrody- namic

Denny, Mark

415

OROGRAPHIC PRECIPITATION Precipitation that has been generated or modified by topography, typically through the forcing of  

E-print Network

OROGRAPHIC PRECIPITATION Precipitation that has been generated or modified by topography, typically rainfall). Orographic effects on precipitation are also responsible for some of the planet's sharpest perpendicular to the prevailing winds, precipitation is greatly enhanced on the windward side and suppressed

Roe, Gerard

416

(abstract) Large-Scale Topography on Main-Belt Asteroids: Evidence from Arecibo Radar Spectra  

NASA Technical Reports Server (NTRS)

Arecibo lambda 13 cm radar spectra of the main belt asteroids 7 Iris, 9 Metis, 12 Victoria, 216 Kleopatra, and 654 Zelinda exhibit evidence for large-scale topography. These asteroids range in diameter from 113 to 200 km and include members of the S,C, and M classes. Radar.

Mitchell, D. L.; Ostro, S. J.; Rosma, K. D.; Campbell, D. B.; Chandler, J. F.; Shapiro, I. I.; Hudson, R. S.

1994-01-01

417

Lithospheric Thickness Variations from Gravity and Topography in Areas of High Crustal Remanent Magnetization on Mars  

NASA Technical Reports Server (NTRS)

Large regions of intense crustal re- manent magnetization were fortuitously discovered on Mars by the Mars Global Surveyor (MGS) spacecraft. Gravity and topography admittance studies are used to examine lithospheric structure in the areas of intense magnetization. Areas with positively magnetized crust appear to have thinner crust and elastic lithosphere than negatively magnetized crust. Additional information is contained in the original extended abstract.

Smrekar, S. E.; Raymond, C. A.

2001-01-01

418

Sea level, topography and island diversity: phylogeography of the Puerto Rican Red-eyed Coqui,  

E-print Network

Sea level, topography and island diversity: phylogeography of the Puerto Rican Red-eyed Coqui´, Eleutherodactylus antillensis BRITTANY S. BARKER,*1 JAVIER A. RODRI´GUEZ-ROBLES, VANI S. ARAN,* ASHLEY MONTOYA of the frog Eleutherodactylus antillensis across the archipelago. We tested hypotheses encompassing vicariance

Rodríguez, Javier A.

419

Two-Layer Shallow Water Equations with Complete Coriolis Force and Topography  

E-print Network

alternative to the empirical friction currently used to regularise existing shallow water models approximation in their unified model [3, 12]. This paper presents a set of two-layer shallow water equationsTwo-Layer Shallow Water Equations with Complete Coriolis Force and Topography A. L. Stewart and P

Stewart, Andrew

420

Illumination conditions of the lunar polar regions using LOLA topography E. Mazarico a,b,,1  

E-print Network

and engineering considerations, we characterized their illumination more precisely over the near future. Every et al., 2010b). LOLA topography combined with a lunar ephemeris (Williams et al., 2008) can be used cold temperatures (Paige et al., 2010) may sequester volatiles such as ice (Watson et al., 1961

Zuber, Maria

421

Modeling of glacier bed topography from glacier outlines, central branch lines, and a DEM  

Microsoft Academic Search

Due to the expected future climate change, glacier ice as a resource will be further diminished and its sea-level rise contribution further increased. A key for a more accurate determination of future glacier evolution is to improve our currently sparse knowledge on glacier bedrock topography. Here, we present a simplified method implemented in a geographic information system to approximate subglacial

Frank Paul; Andreas Linsbauer

2012-01-01

422

Evolutionary modification of development in mammalian teeth: Quantifying gene expression patterns and topography  

PubMed Central

The study of mammalian evolution often relies on detailed analysis of dental morphology. For molecular patterning to play a role in dental evolution, gene expression differences should be linkable to corresponding morphological differences. Because teeth, like many other structures, are complex and evolution of new shapes usually involves subtle changes, we have developed topographic methods by using Geographic Information Systems. We investigated how genetic markers for epithelial signaling centers known as enamel knots are associated with evolutionary divergence of molar teeth in two rodent species, mouse and vole. Our analysis of expression patterns of Fgf4, Lef1, p21, and Shh genes in relation to digital elevation models of developing tooth shapes shows that molecular prepatterns predict the lateral cusp topography more than a day in advance. A heterotopic shift in the molecular prepatterns can be implicated in the evolution of mouse molar, changing locations from which historically homologous cusps form. The subtle but measurable heterotopic shifts may play a large role in the evolution of tooth cusp topographies. However, evolutionary increase in the number of longitudinal cusps in vole molar has involved accelerated longitudinal growth and iterative addition of new cusps without changes in lateral cusp topography. The iterative addition of cusps after the establishment of lateral cusp topography may limit the independence of individual morphological features used in evolutionary studies. The diversity of mammalian molar patterns may largely result from the heterotopic and iterative processes. PMID:11121045

Jernvall, Jukka; Keränen, Soile V. E.; Thesleff, Irma

2000-01-01

423

The topography of grey matter involvement in early and late onset Alzheimer's disease  

E-print Network

The topography of grey matter involvement in early and late onset Alzheimer's disease Giovanni B, The National Centre for Research and Care of Alzheimer's and Mental Diseases, 3 Service of Neuroradiology and Telemedicine, IRCCS Centro San Giovanni di Dio FBF, The National Centre for Research and Care of Alzheimer

Thompson, Paul

424

Serum Pepsinogens as a Predicator of the Topography of Intestinal Metaplasia in Patients with Atrophic Gastritis  

Microsoft Academic Search

The importance of atrophic gastritis with intestinal metaplasia is related to the fact that it increases the risk of gastric cancer development. The aim of this study is to evaluate the diagnostic potential of serum pepsinogens in predicting the topography of intestinal metaplasia. Both dye endoscopy and 13C-urea breath test were carried out in 878 subjects. Serum pepsinogen I, pepsinogen

Yoshihisa Urita; Kazuo Hike; Naotaka Torii; Yoshinori Kikuchi; Eiko Kanda; Masahiko Sasajima; Kazumasa Miki

2004-01-01

425

Cell Adhesion on Polyelectrolyte Multilayer Coated Polydimethylsiloxane Surfaces with Varying Topographies  

E-print Network

Cell Adhesion on Polyelectrolyte Multilayer Coated Polydimethylsiloxane Surfaces with Varying to the pattern size and pitch influences cell adhesion and proliferation. Extensive research has shown the dependence of cell pro- liferation on substrate chemistry, but the influence of substrate topography on cell

Lee, Ilsoon

426

Influence of wet tropospheric correction on mesoscale dynamic topography as derived from satellite altimetry  

Microsoft Academic Search

We study the influence of the wet tropospheric correction on mesoscale dynamic topography as derived from satellite altimetry. For this purpose, we use Geosat altimeter data in the northeast Atlantic, and we process separately the tropospheric correction derived from the PERIDOT model following the technique for analyzing altimeter height profiles. We show that the humidity spatial scales are larger than

D. Jourdan; C. Boissier; A. Braun; J. F. Minster

1990-01-01

427

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

E-print Network

a rigid lithosphere rather than featuring plate tectonics, whereas Mars is similar to Venus in termDeep versus shallow origin of gravity anomalies, topography and volcanism on Earth, Venus and Mars Available online xxxx Keywords: Earth Venus, Interior Mars, Interior Volcanism a b s t r a c t The relation

Steinberger, Bernhard

428

The Skirted Island: The Effect of Topography on the Flow Around Planetary Scale Islands  

E-print Network

and analytical results are presented describing the structure of the flow. A western standing meander at the edge of the island's topography involves a rapid change in the direction of flow and this feature, predicted topographic features, usually in the context of the oceanic abyssal circulation. For example, Katsman (2006