Sample records for topography gmrt synthesis

  1. Global Multi-Resolution Topography (GMRT) Synthesis - Version 2.0

    NASA Astrophysics Data System (ADS)

    Ferrini, V.; Coplan, J.; Carbotte, S. M.; Ryan, W. B.; O'Hara, S.; Morton, J. J.

    2010-12-01

    The detailed morphology of the global ocean floor is poorly known, with most areas mapped only at low resolution using satellite-based measurements. Ship-based sonars provide data at resolution sufficient to quantify seafloor features related to the active processes of erosion, sediment flow, volcanism, and faulting. To date, these data have been collected in a small fraction of the global ocean (<10%). The Global Multi-Resolution Topography (GMRT) synthesis makes use of sonar data collected by scientists and institutions worldwide, merging them into a single continuously updated compilation of high-resolution seafloor topography. Several applications, including GeoMapApp (http://www.geomapapp.org) and Virtual Ocean (http://www.virtualocean.org), make use of the GMRT Synthesis and provide direct access to images and underlying gridded data. Source multibeam files included in the compilation can also accessed through custom functionality in GeoMapApp. The GMRT Synthesis began in 1992 as the Ridge Multibeam Synthesis. It was subsequently expanded to include bathymetry data from the Southern Ocean, and now includes data from throughout the global oceans. Our design strategy has been to make data available at the full native resolution of shipboard sonar systems, which historically has been ~100 m in the deep sea (Ryan et al., 2009). A new release of the GMRT Synthesis in Fall of 2010 includes several significant improvements over our initial strategy. In addition to increasing the number of cruises included in the compilation by over 25%, we have developed a new protocol for handling multibeam source data, which has improved the overall quality of the compilation. The new tileset also includes a discrete layer of sonar data in the public domain that are gridded to the full resolution of the sonar system, with data gridded 25 m in some areas. This discrete layer of sonar data has been provided to Google for integration into Google’s default ocean base map. NOAA coastal grids and numerous grids contributed by the international science community are also integrated into the GMRT Synthesis. Finally, terrestrial elevation data from NASA’s ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) global DEM, and the USGS National Elevation Dataset have been included in the synthesis, providing resolution of up to 10 m in some areas of the US.

  2. GMRT Recreation Club Annual Report

    E-print Network

    Udgaonkar, Jayant B.

    's...............................................................................................................18 10.Movie Club inauguration at GMRT housing colony Narayangaon..............................................21 11.Movie Club Photo......................................................................................................................................43 22.Financial Statement

  3. The GMRT Search for Reionization

    E-print Network

    Ue-Li Pen; Tzu-Ching Chang; Jeff B. Peterson; Jayanta Roy; Yashwant Gupta; Kevin Bandura

    2008-04-15

    We present an overview for the reionization search at GMRT. The forecast sensitivities are promising for an early detection. RFI mitigation has been successful. Several hundred hours of telescope time have already been invested in this ongoing effort, and analysis of the data is in progress.

  4. Synthesis of lunar south pole topography from SMART-1/AMIE imagery and Kaguya Laser Altimeter data

    NASA Astrophysics Data System (ADS)

    Grieger, Bjoern

    The south polar area of the Moon is considered as possible target for future lander missions. Of particular interest is the availability of sunlight on the surface over extended periods of time. Because of the low obliquity of the Moon's rotation axis, it was suspected that there may be peaks which are illuminated most of the year. Theoretically, there could even be one so-called peak of eternal light which is illuminated all the time. The SMART-1 spacecraft operated in an eccentric polar orbit. At the perilune close to the south pole, the image resolution achieved is better than 50 meters per pixel. During the 18 month of science operation, images over a wide range of illumination conditions wereacquired. These allow to search for peaks with favourable lighting. We discovered a peak which is illuminated in almost all images which had captured it (but not in really all images, thus it is not a peak of completely eternal light). It is located at 137° W, 17 km from the south pole. Five images with "small" incidence angle (i. e., close to the smallest occurring value of 88.5° ) and diverse subsolar longitudes were selected to estimate the topography in the vicinity of the found peak with a concerted multiple illumination shape from shading approach. Combining several images with different illumination does not only provide more illuminated area but does also much better constrain the generally ill-posed shape from shading problem. The resultant Digital Terrain Model (DTM) covered a square area of 20 km width with a resolution of 50 meters per pixel. In comparison to this, the topography data retrieved with the Kaguya Laser Altimeter has much lower resolution (about five times) but covers a much larger area (the whole Moon). Herein, we present a new DTM which results from a synthesis of SMART-1/AMIE imagery and Kaguya Laser Altimeter data. The gridded altimeter data is used as additional constraint for the multiple illumination shape from shading procedure. In this way, the altimeter data extends the coverage of the DTM and provides information in areas which are dark in all images, while the images provide high resolution information in their regime.

  5. Synthesis of Acoustic Signals from Buried Seismic Sources in the Presence of Surface Topography

    NASA Astrophysics Data System (ADS)

    Rodgers, A. J.

    2013-12-01

    Buried seismic sources (such as explosions and earthquakes) can generate acoustic motions in the atmosphere by mechanical coupling of ground motion to atmospheric overpressure along the solid-fluid boundary. The Rayleigh Integral has been used to synthesize acoustic overpressure signals from seismic sources where acceleration time-histories along the boundary are inversely weighted by distance, delayed by travel time and summed at an observation point in the far-field. Typically Rayleigh Integral calculations assume a flat surface between Earth's solid and fluid regions, however topography can result in variations of the overpressure signals due to ground motion amplitude differences at the surface and phase differences along the direction of propagation. This study considers the Rayleigh Integral to compute far-field overpressure using seismic ground motion simulations that include an accurate representation of surface topography. Through a series of numerical experiments we will investigate the partitioning of seismoacoustic energy for near-surface seismic events and attempt to quantify the effect of surface topography on overpressure signals.

  6. Visualizing Topography

    NSDL National Science Digital Library

    WGBH Educational Foundation

    2005-12-17

    Explore the topography of a hill, a valley, and a cliff in this interactive activity featuring visualizations of three-dimensional topography in two dimensions. Adapted from Stephen Reynolds' Visualizing Topography.

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

    SciTech Connect

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

    1989-06-01

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

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

    Microsoft Academic Search

    G. Swarup

    1990-01-01

    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

  9. A real-time software backend for the GMRT

    Microsoft Academic Search

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

    2010-01-01

    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

  10. Mars Topography

    NSDL National Science Digital Library

    This educational brief discusses the advances in our knowledge of Mars topography brought about by the high-resolution map produced from Mars Laser Orbiter Altimeter (MOLA) data. Individual features and regions are described along with any new insights provided by MOLA into their origins.

  11. A software baseband receiver for pulsar astronomy at GMRT

    E-print Network

    Bhal Chandra Joshi; Sunil Ramakrishna

    2006-11-10

    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.

  12. A real-time software backend for the GMRT

    E-print Network

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

    2009-01-01

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

  13. GMRT HI observations of the Eridanus group of galaxies

    E-print Network

    A. Omar; K. S. Dwarakanath

    2005-03-24

    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.

  14. Sgr A* at low radio frequencies: GMRT observations

    E-print Network

    Subhashis Roy; A. Pramesh Rao

    2004-02-02

    The central region of the Galaxy has been observed at 580, 620 and 1010 MHz with the Giant Metrewave Radio Telescope (GMRT). We detect emission from Sgr-A*, the compact object at the dynamical centre of the Galaxy, and estimate its flux density at 620 MHz to be 0.5 +/- 0.1 Jy. This is the first detection of Sgr A* below 1 GHz (Roy & Rao 2002, 2003), which along with a possible detection at 330 MHz (Nord et al. 2004) provides its spectrum below 1 GHz. Comparison of the 620 MHz map with maps made at other frequencies indicates that most parts of the Sgr A West HII region have optical depth 2. However, Sgr A*, which is seen in the same region in projection, shows a slightly inverted spectral index between 1010 MHz and 620 MHz. This is consistent with its high frequency spectral index, and indicates that Sgr A* is located in front of the Sgr A West complex, and rules out any low frequency turnover around 1 GHz, as suggested by Davies et al. (1976).

  15. A Deep 150 MHz GMRT Survey in Eridanus

    E-print Network

    Samuel J. George; Ian R. Stevens

    2008-09-24

    We present results of a 150 MHz survey of a field centered on Epsilon Eridani, undertaken with the Giant Metrewave Radio Telescope (GMRT). The survey covers an area with a diameter of 2 deg, has a spatial resolution of 30" and a noise level of 3.1 mJy at the pointing centre. These observations provide a deeper and higher resolution view of the 150 MHz radio sky than the 7C survey (although the 7C survey covers a much larger area). A total of 113 sources were detected, most are point-like, but 20 are extended. We present an analysis of these sources, in conjunction with the NVSS (at 1.4 GHz) and VLSS (at 74 MHz). This process allowed us to identify 5 Ultra Steep Spectrum (USS) radio sources that are candidate high redshift radio galaxies (HzRGs). In addition, we have derived the dN/dS distribution for these observations and compare our results with other low frequency radio surveys.

  16. GMRT Low Frequency Observations of Extrasolar Planetary Systems

    E-print Network

    Samuel George; Ian Stevens

    2007-08-30

    Extrasolar planets are expected to emit detectable low frequency radio emission. In this paper we present results from new low frequency observations of two extrasolar planetary systems (Epsilon Eridani and HD 128311) taken at 150 MHz with the Giant Metrewave Radio Telescope (GMRT). These two systems have been chosen because the stars are young (with ages < 1 Gyr) and are likely to have strong stellar winds, which will increase the expected radio flux. The planets are massive (presumably) gas giant planets in longer period orbits, and hence will not be tidally locked to their host star (as is likely to be the case for short period planets) and we would expect them to have a strong planetary dynamo and magnetic field. We do not detect either system, but are able to place tight upper limits on their low frequency radio emission, at levels comparable to the theoretical predictions for these systems. From these observations we have a 2.5sigma limit of 7.8 mJy for Epsilon Eri and 15.5 mJy for HD 128311. In addition, these upper limits also provide limits on the low frequency radio emission from the stars themselves. These results are discussed and also the prospects for the future detection of radio emission from extrasolar planets.

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

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

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

    E-print Network

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

    2015-01-01

    The intra-cluster medium contains cosmic rays and magnetic fields that are manifested through the large scale synchrotron sources, termed as radio halos, relics and mini-halos. The Extended Giant Metrewave Radio Telescope (GMRT) Radio Halo Survey (EGRHS) is an extension of the GMRT Radio Halo Survey (GRHS) designed to search for radio halos using GMRT 610/235 MHz observations. The GRHS+EGRHS consists of 64 clusters in the redshift range 0.2 -- 0.4 that have an X-ray luminosity larger than 5x10^44 erg/s in the 0.1 -- 2.4 keV band and with declinations > -31 deg in the REFLEX and eBCS X-ray cluster catalogues. In this second paper in the series, GMRT 610/235 MHz data on the last batch of 11 galaxy clusters and the statistical analysis of the full sample are presented. A new mini-halo in RXJ2129.6+0005 and candidate diffuse sources in Z5247, A2552 and Z1953 are discovered. A unique feature of this survey are the upper limits on the detections of 1 Mpc sized radio halos; 4 new are presented here making a total of...

  19. GMRT 150 MHz follow up of diffuse steep spectrum radio emission in galaxy clusters

    NASA Astrophysics Data System (ADS)

    Macario, G.; Venturi, T.; Dallacasa, D.; Giacintucci, S.; Brunetti, G.; Cassano, R.; Ishwara-Chandra, C. H.; Athreya, R.

    It has been recently found that a few galaxy clusters host diffuse radio halo emission with very steep synchrotron spectra (alpha > 1.6), which may be classified as Ultra Steep Spectrum Radio Halos (USSRHs). USSRHs are expected in the turbulence re-acceleration model for the origin of cluster radio halos, and are best discovered and studied at low frequencies. We performed GMRT follow up observations of three galaxy clusters at 150 MHz, selected from the GMRT radio halo survey, which are known to host an USSRH or candidate very steep spectrum diffuse emission. This project is aimed to characterize the low frequency spectrum of USSRHs for a detailed study of their origin and connection with cluster mergers. We present preliminary results at 150 MHz of the cluster A 697.

  20. HI Fluctuations at Large Redshifts: III - Simulating the Signal Expected at GMRT

    E-print Network

    Somnath Bharadwaj; Pennathur Sridharan Srikant

    2004-02-11

    We simulate the distribution of neutral hydrogen (HI) at the redshifts z=1.3 and 3.4 using a cosmological N-body simulation along with a prescription for assigning HI masses to the particles. The HI is distributed in clouds whose properties are consistent with those of the damped Lyman-\\alpha absorption systems (DLAs) seen in quasar spectra. The clustering properties of these clouds are identical to those of the dark matter. We use this to simulate the redshifted HI emission expected at 610 MHz and 325 MHz, two of the observing bands a the GMRT. These are used to predict the correlations expected between the complex visibilities measured at different baselines and frequencies in radio-interferometric observations with the GMRT. The visibility correlations directly probe the power spectrum of HI fluctuations at the epoch when the HI emission originated, and this holds the possibility of using HI observations to study large-scale structures at high z.

  1. Statistics Of Giant Radio Halos: Expectations, and Recent (GMRT) and Future (LOFAR, LWA) Observations

    NASA Astrophysics Data System (ADS)

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

    2006-08-01

    A promising possibility to expalain the existence of giant radio halos (GRHs) in galaxy clusters is given by the "in situ" particle re-acceleration model. This model seems to reproduce the observational properties of the diffuse radio emission. On the other hand the cosmological evolution of GRHs, their statistical properties, and their physical connection with cluster mergers are still issues to be investigated. We have recently carried out the first calculations aimed at deriving the main statistical properties of GRHs in the framework of the electron re-acceleration scenario (Cassano & Brunetti 2005; Cassano, Brunetti, Setti 2006). These calculations allow to derive the occurrence of GRHs with the mass of the parent clusters, the evolution of this occurrence with redshift, and the Luminosity Functions and Number Counts of GRHs at different observing frequencies. The expected occurrence and Number Counts can be tested with present (GMRT and VLA) and future (LOFAR, LWA and SKA) observations. In particular to derive the occurrence of GRHs in the redshift bin 0.2-0.4 and to test our expectations we have carried out relatively deep observations of about 50 massive galaxy clusters at 600 MHz with the GMRT in India. Occurrence with cluster mass: In the first part of this talk I will present the status of the GMRT project (Venturi et al. 2006, submitted), and a first comparison between our theoretical expectations on the occurrence of GRHs with cluster mass and the GMRT results (including also comparison with observations in the redshift bin 0.05-0.2; Giovannini et al. 1999). Number Counts of GRHs: In the second part of the talk I will focus on our results obtained for the Luminosity Functions and for the Number Counts of GRHs at different observing frequencies (50 MHz -- 1.4 GHz). These expectations are important for the interpretation of the future observations with LOFAR and LWA.

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

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

  3. Moire topography in odontology

    NASA Astrophysics Data System (ADS)

    Moreno Yeras, A.

    2001-08-01

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

  4. Low frequency follow up of radio haloes and relics in the GMRT Radio Halo Cluster Survey

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    Aims: To gain insight into the origin of diffuse radio sources in galaxy clusters and their connection with cluster merger processes, we performed GMRT low frequency observations of the radio haloes, relics and new candidates belonging to the GMRT radio Halo cluster sample first observed at 610 MHz. Our main aim was to investigate their observational properties and integrated spectra at frequencies below 610 MHz. Methods: High sensitivity imaging was performed using the GMRT at 325 MHz and 240 MHz. The properties of the diffuse emission in each cluster were compared to our 610 MHz images and/or literature information available at other frequencies, in order to derive the integrated spectra over a wide frequency range. Results: Cluster radio haloes form a composite class in terms of spectral properties. Beyond the classical radio haloes, whose spectral index ? is in the range ~1.2 ÷ 1.3 (S ? ?- ?), we found sources with ? ~ 1.6 ÷ 1.9. This result supports the idea that the spectra of the radiating particles in radio haloes is not universal and that inefficient mechanisms of particle acceleration are responsible for their origin. We also found a variety of brightness distributions, i.e. both centrally peaked and clumpy haloes. Even though the thermal and relativistic plasma tend to occupy the same cluster volume, in some cases a positional shift between the radio and X-ray peaks of emission is evident. Our observations also revealed diffuse cluster sources that cannot be easily classified as either haloes or relics. New candidate relics were found in A 1300 and in A 1682, and in some clusters "bridges" of radio emission have been detected, connecting the relic and radio halo emission. Finally, by combining our new data with information in the literature, we derived the Log LX - Log P325 MHz correlation for radio haloes, and investigated the possible correlation of the spectral index of radio haloes with the temperature of the intracluster medium.

  5. Low Frequency Radio Observations of GRS1915+105 with GMRT

    E-print Network

    C. H. Ishwara-Chandra; A. Pramesh Rao; Mamta Pandey; R. K. Manchanda; Philippe Durouchoux

    2005-12-02

    We present the first detailed low frequency radio measurements of the galactic microquasar GRS1915+105 with GMRT. Simultaneous observations were carried out at 610 and 244 MHz. Our data does not show any signature of spectral turn over even at low radio frequency of 244 MHz. We propose that while the radio emission at high radio frequencies could predominantly come from compact jets, the emission at lower frequency originates in the lobes at the end of the jet which acts like a reservoir of low energy electrons.

  6. Moiré topography in odontology

    NASA Astrophysics Data System (ADS)

    Moreno Yeras, A.

    2003-07-01

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

  7. Flow Interaction with Topography

    NSDL National Science Digital Library

    COMET

    2001-01-01

    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.

  8. TOPOGRAPHIES LAW / DROIT

    E-print Network

    Fabry, Frederic

    THE LAYERS OF LAW TOPOGRAPHIES DU DROIT Faculty of Law Faculté de droit LAW / DROIT AUTOMNE FALL/ 2011 #12;2 FOCUS | LAW ­ FALL / AUTOMNE 2011 ­ MCGILL UNIVERSITY FALL/AUTOMNE 2011 RédactRices en chef Sebastiao, Development Coordinator, alumnioffice.law@mcgill.ca Telephone: 514.398.3679 Focus Law est publié

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

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

    E-print Network

    Sukanta Panda; Subhendra Mohanty; Padmanabhan Janardhan; Oscar Stål

    2007-08-13

    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.

  11. The GMRT EoR Experiment: Limits on Polarized Sky Brightness at 150 MHz

    E-print Network

    Ue-Li Pen; Tzu-Ching Chang; Christopher M. Hirata; Jeffrey B. Peterson; Jayanta Roy; Yashwant Gupta; Julia Odegova; Kris Sigurdson

    2009-05-05

    The GMRT reionization effort aims to map out the large scale structure of the Universe during the epoch of reionization (EoR). Removal of polarized Galactic emission is a difficult part of any 21 cm EoR program, and we present new upper limits to diffuse polarized foregrounds at 150 MHz. We find no high significance evidence of polarized emission in our observed field at mid galactic latitude (J2000 08h26m+26). We find an upper limit on the 2-dimensional angular power spectrum of diffuse polarized foregrounds of [l^2 C_l/(2 PI)]^{1/2} 0.03 h/Mpc, k < 0.1 h/Mpc. This can be compared to the expected EoR signal in total intensity of [k^3 P(k)/ (2 PI^2) ]^{1/2} ~ 10 mK. We find polarized structure is substantially weaker than suggested by extrapolation from higher frequency observations, so the new low upper limits reported here reduce the anticipated impact of these foregrounds on EoR experiments. We discuss Faraday beam and depth depolarization models and compare predictions of these models to our data. We report on a new technique for polarization calibration using pulsars, as well as a new technique to remove broadband radio frequency interference. Our data indicate that, on the edges of the main beam at GMRT, polarization squint creates ~ 3% leakage of unpolarized power into polarized maps at zero rotation measure. Ionospheric rotation was largely stable during these solar minimum night time observations.

  12. Gallery of Virtual Topography

    NSDL National Science Digital Library

    Stephen Reynolds

    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.

  13. Hillslope glacier coupling: The interplay of topography and glacial dynamics in High Asia

    E-print Network

    Bookhagen, Bodo

    Hillslope glacier coupling: The interplay of topography and glacial dynamics in High Asia Dirk. Here we provide a regional synthesis of the topography and flow characteristics of 287 glaciers across High Asia using digital elevation analysis and remotely sensed glacier surface velocities. Glaciers

  14. Corneal topography system

    NASA Astrophysics Data System (ADS)

    Cambier, James L.; Gao, Yan

    1998-03-01

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

  15. GMRT observations of four suspected supernova remnants near the Galactic Centre

    E-print Network

    Subhashis Roy; A. Pramesh Rao

    2001-10-04

    We have observed two fields - Field-I (l=3.2 degrees, b=-1.0 degree) and Field-II (l=356.8 degrees, b=-0.1 degree) with the Giant Metrewave Radio Telescope (GMRT) at 330 MHz. In the first field, we have studied the candidate supernova remnant (SNR) G3.1-0.6 and based on its observed morphology, spectral index and polarisation confirmed it to be an SNR. We find this supernova to have a double ring appearance with a strip of emission on it's western side passing through it's centre. We have discovered two extended curved objects in the second field, which appears to be part of a large shell like structure. It is possibly the remains of an old supernova in the region. Three suspected supernova remnants, G356.3-0.3, G356.6+0.1 and G357.1-0.2 detected in the MOST 843 MHz survey of the Galactic Centre region appears to be located on this shell like structure. While both G356.3-0.3 and G356.6+0.1 seem to be parts of this shell, G357.1-0.2 which has a steeper spectrum above 1 GHz, could be a background SNR seen through the region. Our HI absorption observation towards the candidate SNR G357.1-0.2 indicates that it is at a distance of more than 6 kpc from us.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

  17. Foregrounds for redshifted 21 cm studies of reionization: GMRT 153 MHz observations

    E-print Network

    SK. Saiyad Ali; Somnath Bharadwaj; Jayaram N. Chengalur

    2008-01-16

    Foreground subtraction is the biggest challenge for future redshifted 21 cm observations to probe reionization. We use a short GMRT observation at 153 MHz to characterize the statistical properties of the background radiation across ~ one degree to sub-arcminutes angular scales, and across a frequency band of 5 MHz with 62.5 kHz resolution. The statistic we use is the visibility correlation function, or equivalently the angular power spectrum C_l. We present the results obtained from using relatively unsophisticated, conventional data calibration procedures. We find that even fairly simple minded calibration allows one to estimate the visibility correlation function at a given frequency V_2(U,0). From our observations we find that V_2(U,0) is consistent with foreground model predictions at all angular scales except the largest ones probed by our observations where the the model predictions are somewhat in excess. On the other hand the visibility correlation between different frequencies kappa(U, Delta nu), seems to be much more sensitive to calibration errors. We find a rapid decline in kappa(U, Delta nu), in contrast with the prediction of less than 1 % variation across 2.5 MHz. In this case however, it seems likely that a substantial part of the discrepancy may be due to limitations of data reduction procedures.

  18. RADAR Reveals Titan Topography

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  19. Topography of Io (color)

    NASA Technical Reports Server (NTRS)

    1997-01-01

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

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

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

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

  20. Density, Isostasy, and Topography

    NSDL National Science Digital Library

    Anne Egger

    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.

  1. Topography of chance

    NASA Astrophysics Data System (ADS)

    Eliazar, Iddo I.; Cohen, Morrel H.

    2013-11-01

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

  2. Topography of chance.

    PubMed

    Eliazar, Iddo I; Cohen, Morrel H

    2013-11-01

    We present a model of multiplicative Langevin dynamics that is based on two foundations: the Langevin equation and the notion of multiplicative evolution. The model is a nonlinear mechanism transforming a white-noise input to a dynamic-equilibrium output, using a single control: an underlying convex U-shaped potential function. The output is quantified by a stationary density which can attain a given number of shapes and a given number of randomness categories. The model generates each admissible combination of the output's shape and randomness in a universal and robust fashion. Moreover, practically all the probability distributions that are supported on the positive half-line, and that are commonly encountered and applied across the sciences, can be reverse engineered by this model. Hence, this model is a universal equilibrium mechanism, in the context of multiplicative dynamics, for the robust generation of "chance": the model's output. In turn, the properties of the produced "chance," the output's shape and randomness, are determined with mathematical precision by the control's landscape, its topography. Thus, a topographic map of chance is established. As a particular application, probability distributions with power-law tails are shown to be universally and robustly generated by controls on the "edge of convexity": convex U-shaped potential functions with asymptotically linear wings. PMID:24329211

  3. Global Topography and Tectonic Plates

    NSDL National Science Digital Library

    David Greene

    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.

  4. Deep GMRT 150 MHz observations of the DEEP2 fields: Searching for high redshift radio galaxies revisited

    NASA Astrophysics Data System (ADS)

    Bisoi, Susanta Kumar; Ishwara-Chandra, C. H.; Janardhan, P.

    The well established correlation that shows radio sources exhibiting ultra-steep spectrum are normally at higher redshift. This correlation ensured exploitation of the potential high redshift candidates from the last three decades. In order to continue the search for high redshift radio galaxies, we have extracted the ultra-steep spectrum samples from 150 MHz radio observations of the well-studied DEEP2 deep fields at higher frequencies centered on 1652+3455, 2330+0000 and 0230+000, which were carried out using the Giant Metrewave Radio Telescope (GMRT). We present here one of the observed deep-fields centered on 2330+0000 whose deep 150 MHz GMRT image has an rms noise of ˜0.9 mJy/beam. The source catalog of this deep field contain around 389 sources within 20% peak primary beam response. After careful estimation of spectral indices by cross-correlating each source in our catalog to the already available radio catalogs from NVSS and FIRST surveys at 1400 MHz, we found about 140 steep spectrum radio sources with spectra steeper than 1. We will further study these steep spectrum sources through SDSS and DEEP2 optical catalogs to search potential high redshift candidates.

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

    We report new radio continuum and 21 cm HI observations using the Giant Metrewave Radio Telescope (GMRT) of the group Holmberg 124 (Ho 124) comprising four late-type galaxies, namely NGC 2820, Mrk 108, NGC 2814 and NGC 2805. The three galaxies, NGC 2820, Mrk 108 and NGC 2814 which are closely located in the sky plane have clearly undergone tidal interactions as seen from the various morphological tidal signatures and debris. Moreover we note various features in the group members which we believe might be due to ram pressure. In this paper, we describe four interesting results emerging from our observations: a) detection of the tidal radio continuum bridge at 330 MHz connecting the galaxies NGC 2820+Mrk 108 with NGC 2814. The radio bridge was discovered at 1465 MHz by van der Hulst & Hummel (1985, A&A, 150, 17). We find that the bridge has a fairly steep spectrum with a spectral index ? (S ? ??) of -1.8+0.3-0.2 which is much steeper than the -0.8 quoted by van der Hulst & Hummel (1985); b) detection of other tidal features like the tilted HI and radio continuum disk of NGC 2814, a HI streamer and a radio continuum tail arising from the south of NGC 2814. We also report the detection of a possible tidal dwarf galaxy in HI; c) sharp truncation in the HI distribution in the south of NGC 2820 and in the HI and radio continuum distribution in the north of NGC 2814. The optical disks in both the cases look undisturbed. As pointed out by Davis et al. (1997, AJ, 114, 613), ram pressure affects different components of the interstellar medium to varying degrees. Simple estimates of pressure in different components of the interstellar medium (radio continuum, H? and HI) in NGC 2820 indicate that ram pressure will significantly influence HI; d) detection of a large one-sided HI loop to the north of NGC 2820. No radio continuum emission or H? emission is associated with the HI loop. We discuss various scenarios for the origin of this loop including a central starburst, ram pressure stripping and tidal interaction. We do not support the central starburst scenario since the loop is not detected in ionized gas. Using the upper limit on X-ray luminosity of Ho 124 (Mulchaey et al. 2003, ApJS, 145, 39), we estimate an upper limit on the intragroup medium (IGrM) density of 8.8×10-4 cm-3. For half this electron density, we estimate the ram pressure force of the IGrM to be comparable to the gravitational pull of the disk of NGC 2820. Since tidal interaction has obviously influenced the group, we suggest that the loop could have formed by ram pressure stripping if tidal effects had reduced the surface density of HI in NGC 2820. From the complex observational picture of Ho 124 and the numerical estimates, we suggest that the evolution of the Ho 124 group may be governed by both tidal forces due to the interaction and the ram pressure due to motion of the member galaxies in the IGrM and that the IGrM densities should not be too low (i.e. ? 4×10-4). However this needs to be verified by further observations.

  6. The Shuttle Radar Topography Mission

    Microsoft Academic Search

    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

    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.

  7. Mapping of sea bottom topography

    NASA Technical Reports Server (NTRS)

    Calkoen, C. J.; Wensink, G. J.; Hesselmans, G. H. F. M.

    1992-01-01

    Under suitable conditions the bottom topography of shallow seas is visible in remote sensing radar imagery. Two experiments were performed to establish which remote sensing technique or combination yields optimal imaging of bottom topography and which hydro-meteorological conditions are favorable. A further goal is to gain experience with these techniques. Two experiments were performed over an area in the North Sea near the measuring platform Meetpost Noordwijk (MPN). The bottom topography in the test area is dominated by sand waves. The crests of the sand waves are perpendicular to the coast line and the dominating (tidal-)current direction. A 4x4 sq km wide section of the test area was studied in more detail. The first experiment was undertaken on 16 Aug. 1989. During the experiment the following remote sensing instruments were used: Landsat-Thematic Mapper, and NASA/JPL Airborne Imaging Radar (AIR). The hydro-meteorological conditions; current, wind, wave, and air and water temperature were monitored by MPN, a ship of Rijkswaterstaat (the OCTANS), and a pitch-and-roll WAVEC-buoy. The second experiment took place on 12 July 1992. During this experiment data were collected with the NASA/JPL polarimetric synthetic aperture radar (SAR), and a five-band helicopter-borne scatterometer. Again the hydro-meteorological conditions were monitored at MPN and the OCTANS. Furthermore, interferometric radar data were collected.

  8. Earth rotation and core topography

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  10. Search for steady and transient radio pulses to-wards two new Fermi-LAT sources with GMRT

    NASA Astrophysics Data System (ADS)

    Joshi, Bhal Chandra; McLaughlin, Maura; Lorimer, Duncan; Kramer, Michael; Lyne, Andrew

    The Large Area Telescope aboard Fermi spacecraft has discovered many new pulsars at high energies (Abdo et al. 2009). Sixteen of the 46 sources in this first catalog were discovered at positions of bright gamma-ray sources with no known radio counterparts, suggesting a large radio-quiet pulsar population. The non-detections of radio pulsars in these sources suggest an outer gap origin of the high energy emission and strict upper limits with radio observations of these sources are required. On the other hand, the detection of radio pulsation is useful for an improved timing solution and an estimate of distance. Two of these, PSRs J2238+59 and J1958+2846, without radio counterparts, lie in a region of sky, which was surveyed using GMRT at 610 MHz in a recently concluded radio pulsar survey (Joshi et al. 2009). We present upper limits on pulsed radio emission from our survey for these two sources and the results of a transient search to detect isolated bursts from these sources using the same data.

  11. Quantifying turbidity current interactions with topography

    E-print Network

    Straub, Kyle M

    2007-01-01

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

  12. Bathymetry, Topography, and Relief Data

    NSDL National Science Digital Library

    National Geophysical Data Center

    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.

  13. Venus - Global gravity and topography

    NASA Astrophysics Data System (ADS)

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

    1993-05-01

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

  14. Corneal topography of posterior keratoconus.

    PubMed

    Mannis, M J; Lightman, J; Plotnik, R D

    1992-07-01

    Posterior keratoconus is an unusual abnormality of the cornea generally classified as one of the anterior chamber cleavage anomalies. It is characterized clinically by the presence of a circumscribed or generalized corneal thinning with posterior depression of the cornea and is considered distinct from keratoconus. Although patients with posterior keratoconus may have visual complaints clearly related to their abnormal corneas, the surface topography of these corneas has not been studied in detail. Keratometry and photokeratoscopy provide an incomplete picture of the surface geometry of posterior keratoconus. We utilized computer assisted topographic analysis to study the cornea of a patient with posterior keratoconus. The Topographic Modeling System demonstrated that the patient's cornea showed a central steepened "cone" coincident with the area of circumscribed posterior keratoconus as well as paracentral flattening. This report documents the topographic abnormality in this rare disorder. PMID:1424657

  15. Large scale topography of Io

    NASA Technical Reports Server (NTRS)

    Gaskell, R. W.; Synnott, S. P.

    1987-01-01

    To investigate the large scale topography of the Jovian satellite Io, both limb observations and stereographic techniques applied to landmarks are used. The raw data for this study consists of Voyager 1 images of Io, 800x800 arrays of picture elements each of which can take on 256 possible brightness values. In analyzing this data it was necessary to identify and locate landmarks and limb points on the raw images, remove the image distortions caused by the camera electronics and translate the corrected locations into positions relative to a reference geoid. Minimizing the uncertainty in the corrected locations is crucial to the success of this project. In the highest resolution frames, an error of a tenth of a pixel in image space location can lead to a 300 m error in true location. In the lowest resolution frames, the same error can lead to an uncertainty of several km.

  16. A High Galactic Latitude HI 21cm-line Absorption Survey using the GMRT: II. Results and Interpretation

    E-print Network

    Rekhesh Mohan; K. S. Dwarakanath; G. Srinivasan

    2004-10-26

    We have carried out a sensitive high-latitude (|b| > 15deg.) HI 21cm-line absorption survey towards 102 sources using the GMRT. With a 3-sigma detection limit in optical depth of ~0.01, this is the most sensitive HI absorption survey. We detected 126 absorption features most of which also have corresponding HI emission features in the Leiden Dwingeloo Survey of Galactic neutral Hydrogen. The histogram of random velocities of the absorption features is well-fit by two Gaussians centered at V(lsr) ~ 0 km/s with velocity dispersions of 7.6 +/- 0.3 km/s and 21 +/- 4 km/s respectively. About 20% of the HI absorption features form the larger velocity dispersion component. The HI absorption features forming the narrow Gaussian have a mean optical depth of 0.20 +/- 0.19, a mean HI column density of (1.46 +/- 1.03) X 10^{20} cm^{-2}, and a mean spin temperature of 121 +/- 69 K. These HI concentrations can be identified with the standard HI clouds in the cold neutral medium of the Galaxy. The HI absorption features forming the wider Gaussian have a mean optical depth of 0.04 +/- 0.02, a mean HI column density of (4.3 +/- 3.4) X 10^{19} cm^{-2}, and a mean spin temperature of 125 +/- 82 K. The HI column densities of these fast clouds decrease with their increasing random velocities. These fast clouds can be identified with a population of clouds detected so far only in optical absorption and in HI emission lines with a similar velocity dispersion. This population of fast clouds is likely to be in the lower Galactic Halo.

  17. Maps of Mars Global Topography

    NASA Technical Reports Server (NTRS)

    1999-01-01

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

  18. Phobos' shape and topography models

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

  19. Sensory properties of menthol and smoking topography

    PubMed Central

    2011-01-01

    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

  20. Predicting dynamic topography from mantle circulation models

    NASA Astrophysics Data System (ADS)

    Webb, Peter; Davies, J. Huw

    2013-04-01

    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.

  1. Topography of the synaptosomal membrane

    PubMed Central

    1976-01-01

    The composition and disposition of the constituent polypeptides of rat cerebral cortical synaptosomal membranes were analyzed on SDS acrylamide gels. Of 20 bands readily detected, 11 account for greater than 93% of the total protein analyzed. These are: (molecu25); 3 (175); 4 (doublet, 137); 5 (doublet, 97); 6 (68); 7 (61); 8 (54); 9 (44); 10 (37); and 11 (33). Bands 5 and 8-10 are the most prominent and account for greater than 60% of the protein mass or 0.67 of its molecular fraction. By lactoperoxidase iodination, the bulk of the proteins in bands 3, 5, 6, and 8 and a portion of band 11 appear to be located on the external (junctional) face of the membrane of intact synaptosomes; proteins in bands 1, 2, 7, 9, and 10 appear to be localized on the internal (synaptoplasmic) face and become labeled only when synaptosomes are lysed. Further confirmation of the topographical distribution is provided by evidence that bands 3-6, 8, and 11 contain glycoproteins susceptible to labeling in intact synaptosomes by oxidation with galactose oxidase or periodate followed by reduction with NaB3H4. Evidence is provided for significant contributions by tubulin- and actin-like molecules to bands 8 and 9, respectively, suggesting that a substantial fraction of the tubulin in the synaptosomal membrane is disposed externally (accessible to iodination) whereas most, if not all, of the actin appears to exhibit the opposite topography. Similar though weaker inferences can also be drawn with regard to the location of tropomyosin and troponin. Preliminary evidence is provided that postsynaptic densities exhibit a protein and iodination profile distinct from that of the synpatosomal membrane. PMID:1033185

  2. Corneal topography measurements for biometric applications

    NASA Astrophysics Data System (ADS)

    Lewis, Nathan D.

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

  3. Development of Global Bathymetry and Topography at 15 arc seconds

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

  4. Effects of patterned topography on biofilm formation

    NASA Astrophysics Data System (ADS)

    Vasudevan, Ravikumar

    2011-12-01

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

  5. Detecting and Quantifying Topography in Neural Maps

    PubMed Central

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

    2014-01-01

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

  6. Virtual Field Trip: Temperate Deciduous Forest Topography

    E-print Network

    Hansen, Andrew J.

    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

  7. Ocean Surface Topography from Space - Science

    NSDL National Science Digital Library

    Jet Propulsion Laboratory

    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.

  8. The evolution of topography on a comet

    Microsoft Academic Search

    J. E. Colwell; B. M. Jakosky

    1987-01-01

    The authors have developed a simple model of an infinite cylindrical trench on a comet. The energy balance equation has been modified to include physical processes which are relevant with topography present, and includes shadowing, radiative heating from the opposing walls, and the condensation energy of sublimed gas molecules striking the walls instead of escaping to space. The model is

  9. Sea bottom topography imaging with SAR

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  10. The Belize margin revisited. 2. Origin of Holocene antecedent topography

    Microsoft Academic Search

    Edward G. Purdy; Eberhard Gischler; Anthony J. Lomando

    2003-01-01

    The importance of antecedent topography in dictating Holocene facies patterns has been generally recognized. There is, however, disagreement as to origin or lithology of the antecedent topography, particularly with respect to the siliciclastic or carbonate nature of the underlying topography and structural patterns. To help resolve these problems, published and unpublished information have been compiled to produce a structural fabric

  11. Spatial Fourier Transform Analysis of Polishing Pad Surface Topography

    NASA Astrophysics Data System (ADS)

    Khajornrungruang, Panart; Kimura, Keiichi; Okuzono, Takahisa; Suzuki, Keisuke; Kushida, Takashi

    2012-05-01

    The spatial Fourier transform analysis is proposed to quantitatively evaluate the irregular topography of the conditioned chemical mechanical polishing (CMP) pad surface. We discuss the power spectrum in the spatial wavelengths of the surface topographies corresponding to polishing time. We conclude that the spatial wavelength of less than 5 µm in the topography yielded high material removal rates.

  12. 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)

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

    2005-10-01

    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.

  13. Description of two-process surface topography

    NASA Astrophysics Data System (ADS)

    Grabon, W.; Pawlus, P.

    2014-04-01

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

  14. ATM Coastal Topography-Alabama 2001

    USGS Publications Warehouse

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

    2009-01-01

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

  15. Diffraction imaging (topography) with monochromatic synchrotron radiation

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  16. 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.

  17. ATM Coastal Topography-Mississippi, 2001

    USGS Publications Warehouse

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

    2009-01-01

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

  18. Topography measurement of specular and diffuse surfaces

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

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

  19. Impacts of Topography on Sea Level Change

    NSDL National Science Digital Library

    2007-01-01

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

  20. The topography of the nuclear fission barrier

    Microsoft Academic Search

    J E Lynn

    1989-01-01

    Fission theory first developed within the framework of the liquid drop model. Shell model concepts were introduced into fission\\u000a theory much later than they were in nuclear structure theory, but then with spectacular success in explaining striking experimental\\u000a results then emerging in actinide fission. In the last two decades the complex topography of the fission barrier that is the\\u000a result

  1. EAARL topography: Assateague Island National Seashore

    USGS Publications Warehouse

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

    2007-01-01

    This Web site contains 58 lidar-derived bare earth topography maps and GIS files for the Assateague Island National Seashore. These lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to costal resource managers.

  2. Corneal topography of excimer laser photorefractive keratectomy.

    PubMed

    Klyce, S D; Smolek, M K

    1993-01-01

    The application of the 193 nm excimer laser for keratorefractive surgery promises to deliver a higher degree of precision and predictability than traditional procedures such as radial keratotomy. The development and evaluation of keratorefractive surgery have benefited from the parallel advances made in the field of corneal topography analysis. We used the Computed Anatomy Topography Modeling System (TMS-1) to analyze a Louisiana State University (LSU) Eye Center series of patients who had photorefractive keratectomy for the treatment of myopia with the VISX Twenty/Twenty excimer laser system. The excimer ablations were characterized by a relatively uniform distribution of surface powers within the treated zone. In the few cases that exhibited marked refractive regression, corneal topography analysis showed correlative changes. With topographical analysis, centration of the ablations relative to the center of the pupil could be evaluated. Marked improvement in centration occurred in the patients of LSU Series IIB in which the procedure to locate the point on the cornea directly over the pupil's center during surgery was refined. Corneal topographical analysis provides objective measures of keratorefractive surgical results and is able to measure the precise tissue removal effect of excimer laser ablation without the uncertainties caused by measuring visual acuity alone. Our observations forecast the need for improved aids to center the laser ablations and for the development of a course of treatment to prevent post-ablation stromal remodeling. PMID:8450433

  3. EAARL topography: George Washington Birthplace National Monument

    USGS Publications Warehouse

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

    2007-01-01

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

  4. EAARL topography: Cape Cod National Seashore

    USGS Publications Warehouse

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

    2007-01-01

    This Web site contains 90 Lidar-derived bare earth topography maps and GIS files for the Cape Cod National Seashore. These Lidar-derived topography maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Florida Integrated Science Center (FISC) St. Petersburg, Florida, the National Park Service (NPS), Northeast Coastal and Barrier Network, Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography wthin cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to coastal resource managers.

  5. New insights into the evolution of the FR I radio galaxy 3C 270 (NGC 4261) from VLA and GMRT radio observations

    E-print Network

    Kolokythas, Konstantinos; Giacintucci, Simona; Raychaudhury, Somak; Ishwara-Chandra, C H; Worrall, Diana M; Birkinshaw, Mark

    2015-01-01

    We present Giant Metrewave Radio Telescope (GMRT) 240 MHz observations of the nearby luminous FR I radio source 3C 270, in the group-central elliptical NGC 4261. Combining these data with reprocessed Very Large Array (VLA) 1.55 and 4.8 GHz observations, we produce spectral index maps that reveal a constant spectral index along the jets and a gradual steepening from the ends of the jets through the lobes towards the nucleus. A Jaffe & Perola (JP) model fitted to the integrated spectrum of the source gives an asymptotic low-frequency index of $\\alpha_{inj}=0.53_{-0.02}^{+0.01}$, while JP models fitted to the observed spectral index trend along the lobes allow us to estimate radiative ages of $\\sim29$ Myr and $\\sim37$ Myr for the west and east lobes respectively. Our age estimates are a factor of two lower than the 75-Myr upper limit derived from X-ray data (O'Sullivan et al. 2011). We find unlikely the scenario of an early supersonic phase in which the lobe expanded into the ISM at approximately Mach 6 (350...

  6. Macromolecular Topography Leaps into the Digital Age

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  7. Vacillating jets: baroclinic turbulence and topography

    NASA Astrophysics Data System (ADS)

    Thompson, A. F.

    2009-04-01

    Observations from satellite altimetry and output from high-resolution ocean models indicate that the Southern Ocean is characterised by an intricate web of narrow, meandering, filamentary jets. These jets undergo spontaneous formation, merger and splitting events, and rapid latitude shifts over periods of weeks to months. The role of topography in controlling jet variability is explored using a doubly-periodic, forced-dissipative, two-layer quasi-geostrophic model. The system is forced by a baroclinically-unstable, vertically-sheared mean flow in a domain that is large enough to accommodate multiple jets. The dependence of (i) meridional jet spacing, (ii) time scales of jet variability and (iii) large-scale, domain-averaged transport properties on changes in the length scale and steepness of simple sinusoidal topographical features is analysed. The Rhines scale ?? measures the meridional extent of eddy mixing by a single jet, and the ratio ??/?T, where ?T is the topographic length scale, determines jet behaviour. Multiple, steady jets with fixed meridional spacing are observed when ?? ? ?T or when ?? ? ?T. However when ?? < ?T, a pattern of perpetual jet formation and jet merger dominates the time evolution of the system. This unsteady structure significantly alters the large-scale energetics and transport properties, leading to a reduction in transport by a factor of two if the topography consists of zonally-invariant ridges, and an increase in transport by an order of magnitude or more if the topography consists of two-dimensional sinusoidal bumps. For certain parameters, bumpy topography gives rise to periodic oscillations in jet structure between purely-zonal and topographically-steered states. In these cases, transport is dominated by bursts of mixing associated with the shifts between the two regimes. Unsteady jet behaviour depends crucially on the feedback between changes in mean flow orientation, caused by topographic steering, and the conversion of potential energy to kinetic energy through baroclinic instability, as well as on asymmetric Reynolds stresses created by topographical modifications to the large-scale potential vorticity gradient. It is likely that these processes play a role in the dynamic nature of Southern Ocean jets.

  8. EAARL Coastal Topography - Sandy Hook 2007

    USGS Publications Warehouse

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

    2008-01-01

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

  9. Welcome to Surface Topography: Metrology and Properties

    NASA Astrophysics Data System (ADS)

    Leach, Richard

    2013-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  11. A 360-Degree and -Order Model of Venus Topography

    NASA Technical Reports Server (NTRS)

    Rappaport, Nicole; Plaut, Jeffry J.

    1996-01-01

    This report presents the most recent spherical harmonic topography model of Venus developed at Jet Propulsion Laboratory. It was produced by a spherical harmonic analysis of the most complete set of Magellan altimetry data, augmented by Pioneer Venus and Venera data. The harmonic coefficients of the topography were computed to degree and order 360. Compared to previous topography models, this one has the highest correlation with the gravity field of Venus.

  12. A 360-degree and -order model of Venus topography

    NASA Technical Reports Server (NTRS)

    Rappaport, Nicole; Plaut, Jeffrey J.

    1994-01-01

    This report presents the most recent spherical harmonic topography model of Venus developed at Jet Propulsion Laboratory. It was produced by a spherical harmonic analysis of the most complete set of Magellan altimetry data, augmented by Pioneer Venus and Venera data. The harmonic coefficients of the topography were computed to degree and order 360. Compared to previous topography models, this one has the highest correlation with the gravity field of Venus.

  13. Optic nerve head topography and static perimetry in glaucoma diagnostics

    NASA Astrophysics Data System (ADS)

    Rzendkowski, Marek; Janiec, Slawomir; Momot-Kawalska, Barbara; Blazejewska-Meller, Grazyna

    1998-10-01

    Analysis of the optic nerve head topography and static perimetry, are important in glaucoma diagnostics. Topography of the optic nerve head by Topographic Scanning Systems, carries a lot of planimetric and volumetric values. In this paper, results of optic nerve head topography and static perimetry of 116 primary open angle glaucoma cases, are discussed. Estimating correlation between topographic and perimetric data, the most valuable parameter of the topographic method is carried out. Its values in different stages of glaucoma are given.

  14. A puzzle about the Scandinavian topography

    NASA Astrophysics Data System (ADS)

    Hergarten, S.; Stüwe, K.

    2012-04-01

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

  15. Hydrothermal circulation in fault slots with topography

    NASA Astrophysics Data System (ADS)

    Titarenko, Sofya; McCaig, Andrew

    2014-05-01

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

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

    SciTech Connect

    Lakshmoji, K.; Prabakar, K.; Tripura Sundari, S., E-mail: sundari@igcar.gov.in; Jayapandian, J.; Tyagi, A. K.; Sundar, C. S. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India)

    2014-01-27

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  18. Mean dynamic topography of the Arctic Ocean

    NASA Astrophysics Data System (ADS)

    Farrell, Sinéad Louise; McAdoo, David C.; Laxon, Seymour W.; Zwally, H. Jay; Yi, Donghui; Ridout, Andy; Giles, Katharine

    2012-01-01

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

  19. Mean Dynamic Topography of the Arctic Ocean

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  20. Temporal and spatial distribution of exhumed topography

    NASA Technical Reports Server (NTRS)

    Rhodes, D. D.

    1984-01-01

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

  1. Gravity and topography. [of planet Mars

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  2. Forecasting Hurricane Impact on Coastal Topography

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  3. Architecture and development of olivocerebellar circuit topography

    PubMed Central

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

    2013-01-01

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

  4. The Role of Topography in Glacial Inception

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  5. Bedrock topography beneath the Red Lake peatlands

    SciTech Connect

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

    1992-01-01

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

  6. Mantle transition zone topography and structure beneath the Yellowstone hotspot

    E-print Network

    Dueker, Ken

    Mantle transition zone topography and structure beneath the Yellowstone hotspot David Fee and Ken of the 410 and 660 km discontinuities beneath the Yellowstone hotspot are constrained using common conversion, providing no evidence for a lower mantle plume currently beneath the hotspot. The topography suggests

  7. Video Animation of Ocean Topography From TOPEX/POSEIDON

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  8. Topography and Volcanoes on Io (color)

    NASA Technical Reports Server (NTRS)

    1997-01-01

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

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

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

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

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home 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

  9. Mask topography effect in chromeless phase lithography

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

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

  10. Characterizing smoking topography of cannabis in heavy users

    PubMed Central

    Stitzer, Maxine L.; Vandrey, Ryan

    2013-01-01

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

  11. The effect of topography on the seismic wavefield

    NASA Astrophysics Data System (ADS)

    Miller, Ulrika

    Active tectonic settings exhibit deformation manifested by earthquakes and by strong topographic variations due to erosion and uplift. Seismic waves from these earthquakes will clearly be influenced by the topographic variations, but it is challenging to isolate the effects of topography from the effects of variations in 3D seismic wave-speed structure. Here we design a realistic numerical experiment to investigate the effects of topography on the regional seismic wavefield. We choose southern California as a target region. We perform several sets of 3D seismic wavefield simulations for 137 earthquake sources ranging from Mw 3.4 to 5.4. We test the influence of topography within a homogeneous model and a layered model, and for each model we establish the shortest resolvable period for each path between a source and station. By examining the path-specific shortest resolvable periods, we are able to make some generalizations. Topography has the strongest influence on surface waves, particularly for waveforms with travel paths that are nodal to the source radiation; in these directions, the wave amplitudes are relatively low, so any multi-pathing or scattering effects due to topography are more easily identified. The topographic effects are stronger for shorter periods and for longer paths. The influence of topography on the seismic waveforms arises from both the change in the topographic surface, but also the change in the wave-speed structure that arises from perturbing the topography for a 1D (or 3D) wave-speed model. These generalizations of the influence of topography provide a basis for further numerical investigations or for where to search within a regional set of observations for the topographic effects. Topography should be included within simulation-based seismic imaging applications, especially those at high frequencies, in order to eliminate the possibility of attributing topographically-caused waveforms to subsurface variations in structure.

  12. Predicting Maximum Lake Depth from Surrounding Topography

    PubMed Central

    Hollister, Jeffrey W.; Milstead, W. Bryan; Urrutia, M. Andrea

    2011-01-01

    Information about lake morphometry (e.g., depth, volume, size, etc.) aids understanding of the physical and ecological dynamics of lakes, yet is often not readily available. The data needed to calculate measures of lake morphometry, particularly lake depth, are usually collected on a lake-by-lake basis and are difficult to obtain across broad regions. To span the gap between studies of individual lakes where detailed data exist and regional studies where access to useful data on lake depth is unavailable, we developed a method to predict maximum lake depth from the slope of the topography surrounding a lake. We use the National Elevation Dataset and the National Hydrography Dataset – Plus to estimate the percent slope of surrounding lakes and use this information to predict maximum lake depth. We also use field measured maximum lake depths from the US EPA's National Lakes Assessment to empirically adjust and cross-validate our predictions. We were able to predict maximum depth for ?28,000 lakes in the Northeastern United States with an average cross-validated RMSE of 5.95 m and 5.09 m and average correlation of 0.82 and 0.69 for Hydrological Unit Code Regions 01 and 02, respectively. The depth predictions and the scripts are openly available as supplements to this manuscript. PMID:21984945

  13. Inversion of topography in Martian highland terrains

    SciTech Connect

    De Hon, R.A.

    1985-01-01

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

  14. Topography Simulation for Nanometer Semiconductor Process

    NASA Astrophysics Data System (ADS)

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

    2006-04-01

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

  15. Surface topography and rotational symmetry breaking.

    PubMed

    Basu, Rajratan; Nemitz, Ian R; Song, Qingxiang; Lemieux, Robert P; Rosenblatt, Charles

    2012-07-01

    The surface electroclinic effect, which is a rotation of the molecular director in the substrate plane proportional to an electric field E applied normal to the substrate, requires both a chiral environment and C(2) (or lower) rotational symmetry about E. The two symmetries typically are created in tandem by manipulating the surface topography, a process that conflates their effects. Here we use a pair of rubbed polymer-coated substrates in a twist geometry to obtain our main result, viz., that the strengths of two symmetries, in this case the rub-induced breaking of C(?) rotational symmetry and chiral symmetry, can be separated and quantified. Experimentally we observe that the strength of the reduced rotational symmetry arising from the rub-induced scratches, which is proportional to the electroclinic response, scales linearly with the induced topographical rms roughness and increases with increasing rubbing strength of the polymer. Our results also suggest that the azimuthal anchoring strength coefficient is relatively insensitive to the strength of the rubbing. PMID:23005441

  16. Corneal topography changes after vitreoretinal surgery.

    PubMed

    Azar-Arevalo, O; Arevalo, J F

    2001-01-01

    The authors report the results of a prospective study to assess corneal topography changes after vitreoretinal surgery procedures. Computer-assisted videokeratography using a Topographic Modeling System-1 (TMS-1) were prospectively performed before and after vitreoretinal surgery (vitrectomy with or without scleral buckling) in 12 eyes (patients) with varied vitreoretinal pathology, including cytomegalovirus (CMV) retinitis, CMV-related retinal detachment, retinal detachment with and without proliferative vitreoretinopathy, trauma, acute retinal necrosis, and macular hole. Preoperative and postoperative surface regularity index (SRI), surface asymmetry index (SAI), and induced astigmatism were determined. Patients were followed for an average of 6 months (range: 2-15 months). Mean preoperative SRI was 0.52 (0.05-1.06) and postoperative SRI was 0.73 (0.25-1.36). Mean preoperative SAI was 0.43 (0.22-0.93) and postoperative SAI was 0.56 (0.21-0.99). Mean induced astigmatism was 0.7 diopters. Our study suggests that the central corneal optical quality (SRI) and the asymmetricity of the anterior corneal curvature (SAI) deteriorates after vitreoretinal surgery. PMID:11300644

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  18. Shape, topography, gravity anomalies and tidal deformation of Titan

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

    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.

  19. Length Scale and Scaling in Both Topography Shape and Topography Dynamics

    NASA Astrophysics Data System (ADS)

    Davy, P.

    2003-12-01

    Erosion processes both shapes topography and control topography dynamics so that it should be feasible to constrain the latter from the analysis of the former. During the last ten years, a bunch of studies have been done on analyzing topography in terms of erosion and transport laws. A kind of consensus has emerged around the power-law stream model which assumes that the erosion flux can be adequately described by its dependency on water flow and local topographic slope, and which gives that power laws with threshold are adequate functions to describe these dependencies, and that several processes (i.e. power-law functions) are necessary to cover the complete range of basin areas. But the consequences of these results in terms of dynamics have not been fully appraised yet. Thanks to a numerical surface-process model, we explore the relationship between form and dynamics, and especially the existence of characteristic time scales and their relationship to both structural and erosional parameters. Basically landscape erosion has a two-step evolution: an early phase which corresponds to the onset of drainage network, and a gentle back-to-equilibrium history. The former is very sensitive to initial topographic conditions and its dynamics is intimately related to drainage captures. We are mainly concerned with the latter which gives the long-term response of a continental system to any tectonic or climatic perturbation. Its characteristic time scale ? depends on the system size L in a power-law relationship which defines the nature of the continental-scale diffusion equation. For processes which depends linearly on slope (with or without threshold), this scaling can be written as: ? = ? H * (L/? aH)?, where ? H and aH are the characteristic time scale and drainage area of hillslope, L the system size, and ? the diffusion exponent which only depends on the river process. In all relevant cases, ? is smaller than 1 leading to abnormally fast diffusion. In some cases (if erosion flux is highly dependent on river flux and/or if the sediment are efficiently transported in rivers), ? is 0 and the system evolution is entirely controlled by hillslope dynamics. An analytical solution of ? has been derived with the assumptions described above. We also show that the complete analytical solution of the topography history takes the general form: h(t)=ho exp (-(t/? )?)+h? All parameters will be physically explained and related to system characteristics and erosion transport parameters.

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

    USGS Publications Warehouse

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

    2012-01-01

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

  1. Influence of local topography on precision irrigation management

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  2. Crustal thickness and support of topography on Venus

    E-print Network

    James, Peter Benjamin

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

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

    NASA Technical Reports Server (NTRS)

    Siegel, R.

    1972-01-01

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

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

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

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

  5. THE INFLUENCE OF TOPOGRAPHY AND TEMPERATURE ON QUERCUS ILICIFOLIA SUCCESSION

    E-print Network

    Vallino, Joseph J.

    and tree oak plot. I found that colder microclimates are created by the effects of the low topography ecosystem. It is opportunistic and an early successional species that is maintained by disturbances. Scrub

  6. Geoid height versus topography for oceanic plateaus and swells

    NASA Technical Reports Server (NTRS)

    Sandwell, David T.; Mackenzie, Kevin R.

    1989-01-01

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

  7. Superoleophobic Surfaces through Control of Sprayed-on Stochastic Topography

    E-print Network

    Campos, Raymond

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

  8. Surface topography and the impact on fatigue performance

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  9. Infragravity waves over topography: generation, dissipation, and reflection

    E-print Network

    Thomson, James M. (James McArthur)

    2006-01-01

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

  10. Science in Motion: Isolated Araneiform Topography

    NASA Technical Reports Server (NTRS)

    2007-01-01

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

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

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

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

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

  11. Global dynamic topography: geoscience communities requirements

    NASA Astrophysics Data System (ADS)

    Dewez, T.; Costeraste, J.

    2012-04-01

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

  12. Phase contrast in Simultaneous Topography and Recognition imaging.

    PubMed

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

    2009-08-01

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

  13. Lower mantle heterogeneity, dynamic topography and the geoid

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

  14. Asymmetric three-dimensional topography over mantle plumes

    NASA Astrophysics Data System (ADS)

    Burov, Evgueni; Gerya, Taras

    2014-09-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

  16. Shuttle Topography Data Inform Solar Power Analysis

    NASA Technical Reports Server (NTRS)

    2013-01-01

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

  17. Evolution of Topography in Glaciated Mountain Ranges

    NASA Technical Reports Server (NTRS)

    Brocklehurst, Simon H.

    2002-01-01

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

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

    PubMed

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

    2011-12-01

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

  19. Static and dynamic support of western United States topography

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  20. Plasma Molding over Surface Topography: IED and IAD over Steps

    NASA Astrophysics Data System (ADS)

    Economou, Demetre; Kim, Doosik

    2001-10-01

    Plasma molding over surface topography finds applications in MEMS microfabrication, plasma extraction through grids, and plasma contact with internal reactor parts (e.g., wafer chuck edge). The flux, energy and angular distributions of ions incident on the target are of primary importance in these applications. These quantities depend critically on the shape of the meniscus (plasma-sheath boundary) formed over the surface topography. We have developed a 2-D simulation tool to calculate the flux, energy and angular distribution of ions (and fast neutrals) impinging on surface topography in contact with a high density plasma. Plasma molding over a step has been analyzed in detail. Simulation results will be compared to experimental data as a function of distance from the step obtained at Sandia National Labs.

  1. SPC Shape and Topography of Vesta from DAWN Imaging Data

    NASA Astrophysics Data System (ADS)

    Gaskell, Robert W.

    2012-10-01

    The DAWN spacecraft has now left Vesta, leaving a legacy of more than 16000 clear filter images of the asteroid. During the last month of Dawn's stay at Vesta, the sun slowly crept northward, enabling the spacecraft to view topography closer to the north pole. We have used these images with our stereophotoclinometry (SPC) software to construct topography for most of Vesta's surface to 50 meter resolution, and below about 60 degrees south to 20 meter resolution. We present this topography as a 1/64 degree gridded map (about 70 m resolution), as a stereographic projection of the south polar region at 25 m resolution and as a global shape model with 1.57 million vectors. In addition, we present solutions for the s/c position and camera pointing at all imaging times during DAWN's entire stay at Vesta.

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

    PubMed Central

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

    2008-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1999-01-01

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

  4. Surface topography prediction on laser processed tool steel

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  5. Introduction to Special Section on Tectonics and Topography

    NASA Astrophysics Data System (ADS)

    Merritts, Dorothy; Ellis, Michael

    1994-06-01

    This special section on tectonics and topography developed from an American Geophysical Union Chapman Conference convened in the late summer of 1992 in Snowbird, Utah. The intent of the gathering was to assemble a diverse group of Earth scientists working on ultimately the same problem: the interaction between crustal and surficial processes or, euphemistically, tectonics and topography. Through numerous and enthusiastic conversations, it became clear to us prior to the Chapman Conference that many people were working on the interaction between tectonics and topography but about half of these were either unaware of the others or were aghast at the way in which the others simplified their subject (and vice versa for the other half!). To our delight, the conference brought forth a wonderful array of scientists from virtually all subdisciplines of geology, and the desire for mutual help and a sympathetic ear was palpable.

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

    DOEpatents

    Wereszczak, Andrew A.

    2014-09-02

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

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

    PubMed

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

    2014-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Sheats, Julian Taylor

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

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Bajolet, Flora; Faccenna, Claudio; Funiciello, Francesca

    2014-05-01

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

  11. Venus gravity and topography: 60th degree and order model

    NASA Technical Reports Server (NTRS)

    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

    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.

  12. Sound propagation over uneven ground and irregular topography

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

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

  13. Sound propagation over uneven ground and irregular topography

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    The goal of this research is to develop theoretical, computational, and experimental techniques for predicting the effects of irregular topography on long range sound propagation in the atmosphere. Irregular topography is understood to imply a ground surface that is not idealizable as being perfectly flat or that is no idealizable as having a constant specific acoustic impedance. The focus is on circumstances where the propagation is similar to what might be expected for noise from low-altitude air vehicles flying over suburban or rural terrain, such that rays from the source arrive at angles close to grazing incidence.

  14. Sound propagation over uneven ground and irregular topography

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  15. Assessing the quality of topography from stereo-photoclinometry

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  16. The Impact of Weather & Topography on Landslide Development

    NSDL National Science Digital Library

    Kimbler, Frank

    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 â??Content Materialsâ? section, and the procedure for students to follow is clearly outlined. Additional materials that students may find helpful are located in the â??Supplementary 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.

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  18. Extracting Topographic Features From Shuttle Radar Topography Mission (SRTM) Images

    Microsoft Academic Search

    Wei-wen Feng; Peter Bajcsy

    Abstract This report addresses the problem of extracting topographic features from Shuttle Radar Topography Mission (SRTM) imagery. The features are used for Earth science applications and include slope, curvature, aspect, flow direction, flow accumulation and compound,topographic index (CTI). The objective of our work is (1) to support topographic feature extraction similar to the onein ArcGIS, (2) to provide extraction of

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

    PubMed

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

    2014-01-01

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

  20. An anatomical and functional topography of human auditory cortical areas

    PubMed Central

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

    2014-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

  3. Stress distribution and topography of Tellus Regio, Venus

    NASA Technical Reports Server (NTRS)

    Williams, David R.; Greeley, Ronald

    1989-01-01

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

  4. Smoking topography in tobacco chippers and dependent smokers

    Microsoft Academic Search

    Saul Shiffman

    1996-01-01

    Although most cigarette smokers exhibit signs of tobacco dependence, a subset of this population, referred to as tobacco chippers, does not show characteristic signs of dependence. Few studies have attempted to characterize differences between these groups of smokers. The purpose of the present study was to examine smoking topography in chippers (CH) and dependent smokers (DS). Topographical variables including puff

  5. Analysis of Multiple Manding Topographies during Functional Communication Training

    Microsoft Academic Search

    2009-01-01

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

  6. BIOLOGICAL CYBERNETICS, 69, 109-118. Topography And Ocular Dominance

    E-print Network

    Sejnowski, Terrence J.

    of activity presented simultaneously in both eyes. An important aspect of this model is that ocular dominanceBIOLOGICAL CYBERNETICS, 69, 109-118. Topography And Ocular Dominance: A Model Exploring Positive Edinburgh EH8 9LW UNITED KINGDOM ¡ ¢ £ ¤ ¥ ¦ § ¨ ¦ © £ ¦ Abstract The map from eye to brain

  7. Mass and Local Topography Measurements of Itokawa by Hayabusa

    Microsoft Academic Search

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

    2006-01-01

    The ranging instrument aboard the Hayabusa spacecraft measured the surface topography of asteroid 25143 Itokawa and its mass. A typical rough area is similar in roughness to debris located on the interior wall of a large crater on asteroid 433 Eros, which suggests a surface structure on Itokawa similar to crater ejecta on Eros. The mass of Itokawa was estimated

  8. NEW PHOTORESIST COATING METHOD FOR HIGH TOPOGRAPHY SURFACES

    E-print Network

    Peter, Yves-Alain

    -grooves, and cavities. Thus, the conformal photoresist coating of wafers with 3D microstructures becomes a critical step with high topography on silicon or glass surface because of defects generated in the resist layer during. Electrodeposition of photoresist has been reported as a useful method for 3-D stacks of chips [3] but it requires

  9. Topography of Extracellular Matrix Mediates Vascular Morphogenesis and Migration Speeds

    E-print Network

    Jiang, Yi

    Topography of Extracellular Matrix Mediates Vascular Morphogenesis and Migration Speeds Amy L for wound healing, muscle repair, morphogenesis, new blood vessel growth, and cancer invasion. In this study on Vascular Morphogenesis 2 Introduction The extracellular matrix (ECM) is a major component of the extravascu

  10. Ultrastructural basement membrane topography of the bladder epithelium

    Microsoft Academic Search

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

    2003-01-01

    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

  11. Towards Integrated Design of a Robust Feedback Controller and Topography

    E-print Network

    Van den Hof, Paul

    , a positioning stage is used which can position the tip relative to the sample in all three spatial directions)] is an important tool in micro-, and nano-technology to provide images of sample topography with molecular or even of the vertical feedback loop without sacrificing effective positioning range, by using a combination of a long

  12. THE SURFACE WATER AND OCEAN TOPOGRAPHY (SWOT) MISSION

    Microsoft Academic Search

    Douglas Alsdorf; Erensto Rodriguez; Rosemary Morrow; Nelly Mognard; Juliette Lambin; Parag Vaze; Thierry Lafon

    Satellite altimetry has revolutionized the study of the global oceans for the past two decades by providing unprecedented observations of the ocean surface topography at scales larger than about 200 km and made significant advances in our understanding of global ocean circulation and sea level change. However, the coarse cross-track sampling and measurement precision have prevented resolving scales shorter than

  13. SWOT: The Surface Water & Ocean Topography Satellite Mission

    E-print Network

    SWOT: The Surface Water & Ocean Topography Satellite Mission Doug Alsdorf Byrd Polar Research, lake, and river water storage as a regulator of biogeochemical cycles of Oceans ECCO-2 MIT JPL ocean current model Although altimetry data have significantly advanced the study

  14. Cenozoic Tilting of the Australian Continent due to Dynamic Topography

    NASA Astrophysics Data System (ADS)

    Dicaprio, L.; Gurnis, M.; Muller, R. D.

    2007-12-01

    We investigate the possibility of a mantle-dynamic origin to account for the observed pattern of inundation of the Australian continent in the Cenozoic. Since the Paleocene, the Australian continent has experienced a series of regional marine incursions and regressions, which are inconsistent with the expected flooding history due to changes in eustatic sea level alone. During this time, the Australian continent has undergone no major episodes of mountain building or rifting which might account for these patterns of inundation. Since the Eocene, the Australian plate underwent rapid northward motion as the spreading rate at the South East Indian Ridge increased. As it moved northwards, the Australian plate moved away from a dynamic topography low caused by the sinking Gondwanaland slab beneath the South East Indian Ridge, and towards a dynamic topography low caused by subducted slab material in South East Asia. It is thought that these dynamic topography features at the southern and northern extremes of the Australian plate produce an underlying static and long wavelength dynamic feature over which the Australian plate has migrated through the Cenozoic. This dynamic feature should be expressed by an increase in the latitudinal asymmetry of the Australian dynamic signal. Estimates of the dynamic motion of the Australian plate since the Paleocene are made by matching observed patterns of marine incursion with models of marine inundation. Models of inundation are created by backstripping sediment from present-day topography and dynamic motion is quantified by the displacement needed to approximate the observed flooding according to eustatic sea level. We explore the trend of these displacements according to their paleo-position. Preliminary analysis suggests that the continent is influenced by a dynamic feature that is both temporally and spatially varying. We attempt to interpret the evolving dynamic topography field of Australia in the context of kinematic and 3-D dynamic models of the Australian region which provide an integrated explanation for the patterns of marine inundation in the Cenozoic.

  15. Influence of lunar topography on simulated surface temperature

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  16. Seismic waveform inversion for core-mantle boundary topography

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  17. Allometric scaling of infraorbital surface topography in Homo.

    PubMed

    Maddux, Scott D; Franciscus, Robert G

    2009-02-01

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

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

    E-print Network

    Nikurashin, Maxim (Maxim Anatolevich)

    2009-01-01

    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 ...

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  20. Tectonic geomorphology and hydrocarbon induced topography of the Mid-Channel Anticline, Santa Barbara Basin, California

    E-print Network

    Keller, Ed

    Tectonic geomorphology and hydrocarbon induced topography of the Mid-Channel Anticline, Santa The geomorphology of the western sector of the Mid-Channel Anticline (MCA), Santa Barbara, southern California. Keywords: Active folding; Tectonic geomorphology; Hydrocarbon induced topography 1. Introduction

  1. Evaluation of a pre-treatment assessment to select mand topographies for functional communication training

    Microsoft Academic Search

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

    2009-01-01

    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 mand topographies to incorporate into FCT. In the current study, a mand topography assessment was

  2. Topography and the water cycle in a temperate middle mountain environment: the need for interdisciplinary experiments

    Microsoft Academic Search

    Bruno Ambroise

    1995-01-01

    Two main characteristics of mountainous regions are the large topography-driven lateral redistributions of water and energy, and the considerable topography-related heterogeneities on all scales. These features are difficult to estimate, to incorporate into hydrologic models and to aggregate on the general circulation model grid scale. On the local scale, the topography controls the spatial patterns of water and energy inputs,

  3. High Resolution SAR Interferometry: influence of local topography in the context of glacier monitoring

    E-print Network

    Paris-Sud XI, Université de

    High Resolution SAR Interferometry: influence of local topography in the context of glacier the opportu- nity to measure temperate glacier surface topography and displacement between the two for glacier activity monitoring, by providing regular measure- ments such as surface topography, velocity

  4. Effects of dynamic topography on Australian Paleogeography in the Cenozoic

    NASA Astrophysics Data System (ADS)

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

    2006-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

  6. Effect of extraocular muscle surgery on corneal topography.

    PubMed

    Kwito, S; Sawusch, M R; McDonnell, P J; Gritz, D C; Moreira, H; Evensen, D

    1991-06-01

    A computerized videokeratoscopy system was used to evaluate changes in corneal topography after muscle surgery in 36 eyes of 18 rabbits. Topographic analysis revealed a significant flattening of the cornea in the superior and superotemporal octants after superior rectus recession (mean +/- SE, -1.78 +/- 0.16 diopters) compared with control eyes undergoing a sham procedure (-0.17 +/- 0.18 D; P less than .05). Excision of all rectus muscles caused a generalized corneal flattening (-1.42 +/- 0.13 D; P less than .001). A computerized, finite element model of the globe, including the rectus muscles, demonstrated corneal deformation as a result of extraocular muscle tension; recession of an extraocular muscle in this model caused corneal flattening in the quadrant of the recessed muscle. These data suggest that corneal topography is affected by extraocular muscle tension, corroborating clinical reports of refractive change after strabismus surgery. PMID:2043078

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

    DOEpatents

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

    2008-11-11

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

  8. Defect Analysis in Crystals using X-ray Topography

    SciTech Connect

    Raghothamachar,B.; Dhanaraj, G.; Bai, J.; Dudley, M.

    2006-01-01

    A brief review of X-ray topography - a nondestructive method for direct observation and characterization of defects in single crystals - is presented here. The origin and development of this characterization method and the different techniques derived from it are described. Emphasis is placed on synchrotron X-ray topography and its application in studying various crystal imperfections. Mechanisms of contrast formation on X-ray topographs are discussed, with emphasis on contrast associated with dislocations. Determination of Burgers vectors and line directions of dislocations from analysis of X-ray topographs is explained. Contrast from inclusions is illustrated, and their differentiation from dislocations is demonstrated with the aid of simulated topographs. Contrast arising from the deformation fields associated with cracks is also briefly covered.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    PubMed

    Dai, Zhiyang; Wang, Wei; Wen, Lianxing

    2012-05-15

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

  11. Irregular topography at the Earth’s inner core boundary

    PubMed Central

    Dai, Zhiyang; Wang, Wei; Wen, Lianxing

    2012-01-01

    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

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

    USGS Publications Warehouse

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

    2009-01-01

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

  13. ATM Coastal Topography-Florida 2001: Western Panhandle

    USGS Publications Warehouse

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

    2009-01-01

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

  14. ATM Coastal Topography-Florida 2001: Eastern Panhandle

    USGS Publications Warehouse

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

    2009-01-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  17. Upper Mantle Discontinuity Topography from Thermal and Chemical Heterogeneity

    Microsoft Academic Search

    Nicholas Schmerr; Edward J. Garnero

    2007-01-01

    Using high-resolution stacks of precursors to the seismic phase SS, we investigated seismic discontinuities associated with mineralogical phase changes approximately 410 and 660 kilometers (km) deep within Earth beneath South America and the surrounding oceans. Detailed maps of phase boundary topography revealed deep 410- and 660-km discontinuities in the down-dip direction of subduction, inconsistent with purely isochemical olivine phase transformation

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

    PubMed Central

    Evans, Sarah E; Hoffman, Allison C

    2014-01-01

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

  19. Shuttle radar topography mission produces a wealth of data

    Microsoft Academic Search

    Tom G. Farr; Mike Kobrick

    2000-01-01

    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

  20. Ocean Surface Topography From Space (TOPEX/Poseidon Missions)

    NSDL National Science Digital Library

    A joint US and France project, the TOPEX-Poseidon satellites continuously measure sea surface height. The 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.

  1. Gravity\\/magnetic potential of uneven shell topography

    Microsoft Academic Search

    G. Ramillien

    2002-01-01

    .  ?A fast spherical harmonic approach enables the computation of gravitational or magnetic potential created by a non-uniform\\u000a shell of material bounded by uneven topographies. The resulting field can be evaluated outside or inside the sphere, assuming\\u000a that density of the shell varies with latitude, longitude, and radial distance. To simplify, the density (or magnetization)\\u000a source inside the sphere is assumed

  2. Moho depth and residual topography of the Antarctic continent

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  3. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  5. Evaluation of a pre-treatment assessment to select mand topographies for functional communication training.

    PubMed

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

    2009-01-01

    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 mand topographies to incorporate into FCT. In the current study, a mand topography assessment was conducted following functional analyses to identify the proficiency with which individuals used several different mand topographies. Two mand topographies (high and low proficiency) were then compared during FCT-based treatments. FCT was more effective when the mand topography identified as high proficiency was incorporated into FCT as compared to FCT that included the lower proficiency response. The results are discussed in terms of the need for individualized assessment procedures for selecting mand topographies that are targeted during FCT. PMID:18672344

  6. Puffing Topography and Nicotine Intake of Electronic Cigarette Users

    PubMed Central

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

    2015-01-01

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

  7. Global snowline and mountain topography: a contrasted view

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  8. Open questions in surface topography measurement: a roadmap

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Control of surface topography has always been of vital importance for manufacturing and many other engineering and scientific disciplines. However, despite over one hundred years of quantitative surface topography measurement, there are still many open questions. At the top of the list of questions is ‘Are we getting the right answer?’ This begs the obvious question ‘How would we know?’ There are many other questions relating to applications, the appropriateness of a technique for a given scenario, or the relationship between a particular analysis and the function of the surface. In this first ‘open questions’ article we have gathered together some experts in surface topography measurement and asked them to address timely, unresolved questions about the subject. We hope that their responses will go some way to answer these questions, address areas where further research is required, and look at the future of the subject. The first section ‘Spatial content characterization for precision surfaces’ addresses the need to characterise the spatial content of precision surfaces. Whilst we have been manufacturing optics for centuries, there still isn’t a consensus on how to specify the surface for manufacture. The most common three methods for spatial characterisation are reviewed and compared, and the need for further work on quantifying measurement uncertainties is highlighted. The article is focussed on optical surfaces, but the ideas are more pervasive. Different communities refer to ‘figure, mid-spatial frequencies, and finish’ and ‘form, waviness, and roughness’, but the mathematics are identical. The second section ‘Light scattering methods’ is focussed on light scattering techniques; an important topic with in-line metrology becoming essential in many manufacturing scenarios. The potential of scattering methods has long been recognized; in the ‘smooth surface limit’ functionally significant relationships can be derived from first 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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  10. SAR interferometry at Venus for topography and change detection

    NASA Astrophysics Data System (ADS)

    Meyer, Franz J.; Sandwell, David T.

    2012-12-01

    Since the Magellan radar mapping of Venus in the early 1990’s, techniques of synthetic aperture radar interferometry (InSAR) have become the standard approach to mapping topography and topographic change on Earth. Here we investigate a hypothetical radar mission to Venus that exploits these new methods. We focus on a single spacecraft repeat-pass InSAR mission and investigate the radar and mission parameters that would provide both high spatial resolution topography as well as the ability to detect subtle variations in the surface. Our preferred scenario is a longer-wavelength radar (S or L-band) placed in a near-circular orbit at 600 km altitude. Using longer wavelengths minimizes the required radar bandwidth and thus the amount of data that will be transmitted back to earth; it relaxes orbital control and knowledge requirements. During the first mapping cycle a global topography map would be assembled from interferograms taken from adjacent orbits. This approach is viable due to the slow rotation rate of Venus, causing the interferometric baseline between adjacent orbits to vary from only 11 km at the equator to zero at the inclination latitude. To overcome baseline decorrelation at lower latitudes, the center frequency of a repeated pass will be adjusted relative to the center frequency of its reference pass. During subsequent mapping cycles, small baseline SAR acquisitions will be used to search for surface decorrelation due to lava flows. While InSAR methods are used routinely on Earth, their application to Venus could be complicated by phase distortions caused by the thick Venus atmosphere.

  11. TIME SPENT WITH SMOKING PARENTS AND SMOKING TOPOGRAPHY IN ADOLESCENTS

    PubMed Central

    Collins, Charles C.; Lippmann, Brad M.; Lo, Suzanne J.; Moolchan, Eric T.

    2008-01-01

    Although the relationship between parental and adolescent smoking has been linked to health consequences of smoking, limited study has explored the specific association between exposure to smoking and adolescent smoking topography (the way a cigarette is smoked). As a first step in this line of enquiry, smoking topography measures were collected from 67 adolescent dependent smokers. Participants smoked one cigarette of their own brand while being monitored by a computer-based smoking-topography unit and completed questionnaires about their time spent daily with parents who smoke. Pearson’s correlation analysis revealed that time spent daily with parents who smoke was significantly associated with maximum puff velocity (r = 0.285, p = .019), a parameter predicting later pulmonary morbidity. ANOVAs, after a median split, were consistent with correlation analyses. There was a significant group effect on puff velocity (F(2,66) = 5.197, p = .008); no significant relationship was found with puff volume (F(2,66) = .617) or puff duration (F(2,66) = .776). A post hoc Tukey HSD test indicated puff velocity was higher in the “high time spent” (M = 54.37, SD = 12.03) than in the “low time spent” group (M 0 45.59, SD = 9.91) and in the group with non-smoking parents (M = 44.96, SD = 10.17). Future research with a larger non-treatment seeking sample of adolescents aimed at preventing tobacco smoking related diseases should further examine parental influences on adolescent smoking, including potential modeling effects. PMID:18755550

  12. Corneal Topography Analysis of Stromal Corneal Dystrophies

    PubMed Central

    Kocluk, Yusuf; Yalniz-Akkaya, Zuleyha; Burcu, Ayse; Ornek, Firdevs

    2015-01-01

    Objective: The aim was to compare the corneal topography and tomography parameters of macular corneal dystrophy (MCD), granular corneal dystrophy (GCD) and lattice corneal dystrophy (LCD) patients obtained by Scheimpflug imaging system. Methods: The charts, photographs and topography images of patients were reviewed retrospectively. This study included 73 eyes of 73 patients (28 MCD, 20 GCG and 25 LCD patients). Topography images were obtained by Pentacam (Oculus Optikgerate, Wetzlar, Germany). The densitometry readings at the corneal apex were used for the statistics. Results: The female to male ratio was 13/15 in MCD group, 12/8 in GCD group and 13/12 in LCD group. The mean age median age was 32, 45 and 53 years in MCD, GCD and LCD groups respectively. The groups were similar regarding the gender (p=0.861). The MCD group was significantly younger than the other two groups (p<0.001). The median (minmum-maximum) corneal densities were 100 (100-100), 68 (17-100) and 97 (34-100) Pentacam densitometry units in MCD, GCD and LCD groups respectively. The corneal density at the corneal apex was significantly higher in MCD group than in the other groups (p<0.001). The GCD and LCD groups were statistically similar in terms of density of the corneal apex (p=0.079). In MCD group, corneal thickness at the apex and at the thinnest location was significantly thinner, than in the other groups (p=.002 for thickness at apex between MCD and LCD, and p<.001 for all the remaining comparisons). In MCD group corneal volume was significantly smaller than in the other groups (p<.001 for all comparisons). Conclusion: Densitometry on Scheimpflug imaging system gives information on the density of corneal opacities.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    PubMed Central

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

    2011-01-01

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

  15. Scaling of shortwave radiation fluxes for sub grid topography

    NASA Astrophysics Data System (ADS)

    Helbig, N.; Loewe, H.; Adams, E. E.

    2011-12-01

    Shortwave radiation plays an important role in the surface energy balance for understanding mass balances, snow cover distribution as well as snow melt. Incident shortwave radiation is greatly altered by mountainous terrain. While distributed radiation balance models can account for all topographic influences at small scales, for larger scale applications, such as climate and hydrological models, physically based sub grid parameterizations are required. We present a complete shortwave radiation parameterization scheme for sub grid topography accounting for shading, limited sky view and terrain reflections. Each radiative flux is parameterized individually. The parameters required are sun elevation angle, domain-averaged surface albedo and terrain parameters such as slope angle, slope distribution and sky view factor. We show that the domain-averaged sky view factor as an important parameter of the scheme can be theoretically related to the slope distribution. This suggests that the parametrization can solely be computed from slope characteristics and the numerically expensive computation of horizons angles can be abandoned. To validate the parameterization scheme we used domain-averaged values from a detailed radiation balance model for the three-dimensional radiative transfer in complex terrain. In order to minimize influences in the modeled distributed radiation arising from specific geomorphology and climate we compiled a large ensemble of several thousand Gaussian topographies with a broad range of characteristic scales and used fixed sun positions. Overall, modeled radiation from the simulated topographies compared well with parameterized values. We found that depending on sun elevation angles, shading and limited sky view alter direct beam and diffuse sky radiation by up to 40% each. We confirmed that when using domain-averaged values, multiple, anisotropic terrain reflections can be approximated with single, isotropic terrain reflections.

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

    USGS Publications Warehouse

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

    2009-01-01

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

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

    USGS Publications Warehouse

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

    2008-01-01

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

  18. EAARL Coastal Topography - Fire Island National Seashore 2007

    USGS Publications Warehouse

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

    2008-01-01

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

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

    USGS Publications Warehouse

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

    2008-01-01

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

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

    USGS Publications Warehouse

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

    2011-01-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

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

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

    USGS Publications Warehouse

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

    2010-01-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

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

  5. Pre-glacial topography of the European Alps

    NASA Astrophysics Data System (ADS)

    Sternai, P.; Herman, F.; Champagnac, J.-D.; Fox, M.; Salcher, B.; Willett, S. D.

    2012-04-01

    We present a reconstruction of the Alpine topography prior to Quaternary glaciation, based on the assumption that the pre-glacial topography of the Alps was a fluvial landscape in equilibrium with tectonic and isostatic rock uplift. Amongst the models that have been proposed, the stream-power law has been profitably used for modeling the dynamics of fluvial bedrock channel incision: dz-= U - KAmSn dt (1) where dz/dt (m a-1) is the time rate of change of channel elevation, U(m a-1) is rock-uplift rate, A(m) is upstream drainage area, S is local channel gradient, K is a dimensionless coefficient of erosion and m and n are positive constants related to basin hydrology and erosion process. Under steady-state conditions (dz/dt = 0), equation (1) can be solved to yield an expression for equilibrium channel gradient: 1 ( U-)n - (m) S = K A n (2) where the ratios U/K and m/n are generally referred to as the steepness and concavity index, respectively. Particular focus is put on the spatial variability of the steepness index over the Alpine mountain belt. Assuming a constant concavity index, the pre-glacial topography of the Alps is obtained through an inversion technique that resolves local slopes (as described in eq. 2) by minimizing the misfit between the elevations of the actual and modeled channel heads. Comparing the present-day and reconstructed pre-glacial topography, we infer patterns and magnitudes of exhumation and rock uplift produced by Quaternary glaciation in the Alps. We find a correspondence between rock type and pre-glacial channel steepness which may indicate that rock erodibility has a significant importance in determining the pre-glacial fluvial network elevation. Our results also provide insight into patterns of glacial erosion and associated isostatic adjustment, and provide estimates of the increase of valley-scale topographic relief and decrease of mean elevation that glaciation seems to have produced in the Alps.

  6. EAARL Topography - George Washington Birthplace National Monument 2008

    USGS Publications Warehouse

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

    2009-01-01

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

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

    USGS Publications Warehouse

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

    2008-01-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

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

  9. X-ray topography study of complex silicon microcircuits

    NASA Technical Reports Server (NTRS)

    Parker, D. L.

    1981-01-01

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

  10. Dynamic Topography during Flat Subduction: Subsidence or Uplift?

    NASA Astrophysics Data System (ADS)

    Davila, F. M.; Lithgow-Bertelloni, C. R.

    2011-12-01

    Since the first studies on dynamic topography and basin evolution, low-dipping subduction has been related to intracontinental, long-wavelength and high-amplitude subsidence, whereas retreating to normal subduction systems to uplift. This was proposed to explain the Cretaceous-early Cenozoic topographic evolution of the western US. However, modern flat-slab and slab-retreating segments of South America do not record such a subsidence and uplift patterns. For example, the flat slab of Peru at ˜10°SL, related to the subduction of the Nazca Ridge, underlies an elevated promontory known as the Fitzcarrald Arch. The Argentine flat-slab at ˜31°SL associated to the subduction of the Juan Fernandez Ridge underlies a high-elevated intermontane system known as the Pampean broken foreland. Both upwarping features are younger than 7 Ma and contemporaneous with the arrival of flat subduction to these segments. In order to shed light into this controversy, we calculate dynamic topography along the Andean flat-slab segments using the Hager and O'Connell (1981) instantaneous flow formulation, an accurate reconstruction of the slab geometry along the central Andes and a density contrast between the flat slabs and the country mantle close to zero (???0) in order to simulate a buoyant oceanic lithosphere. We demonstrate that dynamic subsidence develops only at the leading edge of flat subduction, where the slabs plunge >30°, whereas the flatter slabs reproduce minor or no dynamic topography signals. These results agree with geological and geophysical proxies. Along the Argentine Plains, the <7 Ma maximum sedimentary accumulation coeval with the age of the flat subduction, plus the maximum modern relief account for a accumulated relief of ˜200 m, which might be considered as an "observed dynamic subsidence" signal (given that no tectonic activity has been recorded in this region since the Cretaceous to explain this surface topography). This gives a ˜0.03 mm/yr dynamic subsidence rate that are curiously similar to the exhumations estimated by low-temperature thermochronology along the Andean foreland (Dávila, 2011).

  11. Topography of the Moon from the Clementine Lidar

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  12. EAARL submarine topography: Florida Keys National Marine Sanctuary

    USGS Publications Warehouse

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

    2007-01-01

    This Web site contains 46 Lidar-derived submarine topography maps and GIS files for the Florida Keys National Marine Sanctuary. These Lidar-derived submarine topographic maps were produced as a collaborative effort between the U.S. Geological Survey (USGS) Coastal and Marine Geology Program, FISC St. Petersburg, Florida, the National Oceanic and Atmospheric Administration (NOAA), Remote Sensing Division, the National Park Service (NPS) South Florida/Caribbean Network Inventory and Monitoring Program, and the National Aeronautics and Space Administration (NASA) Wallops Flight Facility. One objective of this research is to create techniques to survey coral reefs and barrier islands for the purposes of geomorphic change studies, habitat mapping, ecological monitoring, change detection, and event assessment. As part of this project, data from an innovative instrument under development at the NASA Wallops Flight Facility, the NASA Experimental Airborne Advanced Research Lidar (EAARL) are being used. This sensor has the potential to make significant contributions in this realm for measuring subaerial and submarine topography within cross-environment surveys. High spectral resolution, water-column correction, and low costs were found to be key factors in providing accurate and affordable imagery to coastal resource managers.

  13. Multiview hyperspectral topography of tissue structural and functional characteristics

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  16. Surface topography of 1€ coin measured by stereo-PIXE

    NASA Astrophysics Data System (ADS)

    Gholami-Hatam, E.; Lamehi-Rachti, M.; Vavpeti?, P.; Grlj, N.; Pelicon, P.

    2013-07-01

    We demonstrate the stereo-PIXE method by measurement of surface topography of the relief details on 1€ coin. Two X-ray elemental maps were simultaneously recorded by two X-ray detectors positioned at the left and the right side of the proton microbeam. The asymmetry of the yields in the pixels of the two X-ray maps occurs due to different photon attenuation on the exit travel path of the characteristic X-rays from the point of emission through the sample into the X-ray detectors. In order to calibrate the inclination angle with respect to the X-ray asymmetry, a flat inclined surface model was at first applied for the sample in which the matrix composition and the depth elemental concentration profile is known. After that, the yield asymmetry in each image pixel was transferred into corresponding local inclination angle using calculated dependence of the asymmetry on the surface inclination. Finally, the quantitative topography profile was revealed by integrating the local inclination angle over the lateral displacement of the probing beam.

  17. Tropical Pacific response to continental ice sheet topography

    NASA Astrophysics Data System (ADS)

    Chiang, J. C.; Lee, S.

    2013-12-01

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

  18. Smoking topography and outcome expectancies among individuals with schizotypy

    PubMed Central

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

    2013-01-01

    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

  19. Topography and Areal Organization of Mouse Visual Cortex

    PubMed Central

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

    2014-01-01

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

  20. Photoswitchable hydrogel surface topographies by polymerisation-induced diffusion.

    PubMed

    Stumpel, Jelle E; Liu, Danqing; Broer, Dirk J; Schenning, Albertus P H J

    2013-08-12

    Herein, we describe the preparation of patterned photoresponsive hydrogels by using a facile method. This polymer-network hydrogel coating consists of N-isopropylacrylamide (NIPAAM), cross-linking agent tripropylene glycol diacrylate (TPGDA), and a new photochromic spiropyran monoacrylate. In a pre-study, a linear NIPAAM copolymer (without TPGDA) that contained the spiropyran dye was synthesised, which showed relatively fast photoswitching behaviour. Subsequently, the photopolymerisation of a similar monomer mixture that included TPGDA afforded freestanding hydrogel polymer networks. The light-induced isomerisation of protonated merocyanine into neutral spiropyran under slightly acidic conditions resulted in macroscopic changes in the hydrophilicity of the entire polymer film, that is, shrinkage of the hydrogel. The degree of shrinkage could be controlled by changing the chemical composition of the acrylate mixture. After these pre-studies, a hydrogel film with spatially modulated cross-link density was fabricated through polymerisation-induced diffusion, by using a patterned photomask. The resulting smooth patterned hydrogel coating swelled in slightly acidic media and the swelling was higher in the regions with lower cross-linking densities, thus yielding a corrugated surface. Upon exposure to visible light, the surface topography flattened again, thus showing that a hydrogel coating could be created, the topography of which could be controlled by light irradiation. PMID:23821576

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

    NASA Astrophysics Data System (ADS)

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

    1990-06-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

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

    USGS Publications Warehouse

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

    2012-01-01

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

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

    PubMed

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

    2012-01-01

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

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

    USGS Publications Warehouse

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

    2009-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Schenk, Paul M.

    2014-11-01

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

  7. Gravity and topography of Venusian highlands: Implications for formation mechanisms

    NASA Astrophysics Data System (ADS)

    Smrekar, Suzanne Elizabeth

    Gravity and topography data are used to determine the apparent compensation depths (ADC's) of thirteen venusian regions. The depths are interpreted in terms of the likely tectonic origins of each area. First, three geologically distinct regions are studied in detail by inverting Pioneer Venus line of sight gravity data to obtain a model of vertical gravity over Bell Regio (possible hot spot), Tellus Regio (tessera terrain), and Leda Planitia (plains). The admittance spectra, the geoid to topography ratio (GTR), and the ADC for each region are found. Each area has a distinct gravity signature. The shallow ADC at Tellus Regio (approximately 25 km) indicates that crustal compensation, possibly with some thermal compensation, is most likely. The large ADC (approximately 175 km) and GTR (20 m/km) along with an unusual admittance spectra at Bell Regio indicate that some dynamic compensation is necessary; crustal or thermal compensation may also be present. Leda Planitia has an intermediate ADC (approximately 65 km), which indicates either thermal or crustal compensation. Second, ADC's and GTR's for 12 venusian highland regions are estimated directly from the topography and line of sight gravity data. These features are: Asteria, Atla, Bell, Beta, Ovda, Phoebe, Tellus, Thetis, and Ulfrun Regiones; Nokomis, Gula, and Sappho Montes. The ADC's range is 50-270 km; the GTR's range is 7-31 m/km. Two distinct GTR groups are apparent. The lower GTR group is best modeled by compensation due to thermal thinning of the lithosphere; some minor component of dynamic or crustal compensation may also be present. A fit to the upper GTR group requires dynamic compensation; a lesser contribution from thermal or crustal compensation may also be present. Upper mantle convection without a low viscosity zone can fit the data. Although the convection parameters are not well constrained, the best fit occurs for a conductive lid thickness of 105 km and a Rayleigh number of 105. These results indicate that hot spots are likely to make a significant contribution to heat loss on Venus.

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

    NASA Astrophysics Data System (ADS)

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

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

  9. Optic disc topography of normal tension glaucoma patients in Malaysia.

    PubMed

    Adlina, Abdul Rahim; Shatriah, Ismail; Liza Sharmini, Ahmad Tajudin; Ahmad, Mt Saad

    2013-08-01

    There are limited data in the literature on the optic disc topography in normal tension glaucoma (NTG) patients in Asian countries, especially in Southeast Asia. This study is aimed at comparing optic disc topography in NTG patients and a control group in Malaysia, and we discuss the literature on NTG studies in other Asian populations. A comparative cross-sectional study was conducted in two hospitals with glaucoma services in Malaysia from November 2010 to February 2012. A total of 109 eyes of 109 Malay patients were included in this study: 32 NTG patients and 77 subjects in the control group. All participants underwent a thorough ocular examination, including visual acuity, subjective refraction, anterior segment and fundus examinations, Humphrey visual field 24-2, intraocular pressure measurement, gonioscopy examination and fundus photography. Optic disc topography was assessed using the Heidelberg Retinal Tomograph III by an identified masked investigator in each hospital. NTG patients had a notably larger disc area (2.65 (0.41) vs 2.19 (0.43) mm(2), respectively), larger cupping (1.54 (0.43) vs 0.63 (0.40) mm(2), respectively), smaller retinal rim areas (1.12 (0.41) vs 1.56 (0.33) mm(2), respectively), higher cup volume (0.47 (0.28) vs 0.11 (0.19) mm(3), respectively), reduced rim volume (0.23 (0.13) vs 0.41 (0.16) mm(3), respectively), higher cup to disc area ratio (0.58 (0.14) vs 0.27 (0.15), respectively), higher linear cup to disc ratio (0.76 (0.09) vs 0.49 (0.17) mm(2), respectively), higher mean cup depth (0.37 (0.09) vs 0.22 (0.09) mm, respectively), higher maximum cup depth (0.77 (0.16) vs 0.59 (0.20) mm, respectively), higher mean of cup shape measure (-0.04 (0.06) vs -0.16 (0.07), respectively), and thinner mean retinal nerve fibre layer thickness (0.15 (0.15) vs 0.24 (0.07) mm, respectively) compared to the control group (p<0.05). In conclusion, most of the optic disc parameters were significantly different in NTG patients compared to healthy individuals in Malaysia. Our findings are comparable to those reported in NTG studies in other Asian countries. PMID:24145263

  10. Topography measurements for correlations of standard cartridge cases

    NASA Astrophysics Data System (ADS)

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

    2010-06-01

    The National Institute of Standards and Technology Standard Reference Materials (SRM) 2460 Standard Bullets and 2461 Standard Cartridge Cases are intended for use as check standards for crime laboratories to help verify that their computerized optical imaging equipment for ballistics image acquisitions and correlations is operating properly. Using topography measurements and cross-correlation methods, our earlier results for the SRM bullets and recent results for the SRM cartridge cases both demonstrate that the individual units of the SRMs are highly reproducible. Currently, we are developing procedures for topographic imaging of the firing pin impressions, breech face impressions, and ejector marks of the standard cartridge cases. The initial results lead us to conclude that all three areas can be measured accurately and routinely using confocal techniques. We are also nearing conclusion of a project with crime lab experts to test sets of both SRM cartridge cases and SRM bullets using the automated commercial systems of the National Integrated Ballistics Information Network.

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

    PubMed

    Belin, M W

    1993-01-01

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

  12. Different Approach to the Aluminium Oxide Topography Characterisation

    SciTech Connect

    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

    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.

  13. Upper mantle discontinuity topography from thermal and chemical heterogeneity.

    PubMed

    Schmerr, Nicholas; Garnero, Edward J

    2007-10-26

    Using high-resolution stacks of precursors to the seismic phase SS, we investigated seismic discontinuities associated with mineralogical phase changes approximately 410 and 660 kilometers (km) deep within Earth beneath South America and the surrounding oceans. Detailed maps of phase boundary topography revealed deep 410- and 660-km discontinuities in the down-dip direction of subduction, inconsistent with purely isochemical olivine phase transformation in response to lowered temperatures. Mechanisms invoking chemical heterogeneity within the mantle transition zone were explored to explain this feature. In some regions, multiple reflections from the discontinuities were detected, consistent with partial melt near 410-km depth and/or additional phase changes near 660-km depth. Thus, the origin of upper mantle heterogeneity has both chemical and thermal contributions and is associated with deeply rooted tectonic processes. PMID:17962558

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

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

  15. Forecasting hurricane impact on coastal topography: Hurricane Ike

    USGS Publications Warehouse

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

    2010-01-01

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

  16. Dynamic wetting and spreading and the role of topography

    NASA Astrophysics Data System (ADS)

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

    2009-11-01

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

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

    USGS Publications Warehouse

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

    1977-01-01

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

  18. Adaptive Topographies and Equilibrium Selection in an Evolutionary Game

    PubMed Central

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

    2015-01-01

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

  19. Adaptive topographies and equilibrium selection in an evolutionary game.

    PubMed

    Osinga, Hinke M; Marshall, James A R

    2015-01-01

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

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

    PubMed

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

    2012-06-26

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

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

    NASA Technical Reports Server (NTRS)

    1992-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  3. Mercury's global shape and topography from MESSENGER limb images

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    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.

  4. Development of the airborne lidar surface topography simulator

    NASA Astrophysics Data System (ADS)

    Yu, Anthony W.; Harding, David J.; Krainak, Michael A.; Abshire, James B.; Sun, Xiaoli; Cavanaugh, John; Valett, Susan; Ramos-Izquiedro, Luis; Winkert, Tom; Plants, Michael; Kirchner, Cynthia; Kamamia, Brian; Hasselbrack, William; Filemyr, Timothy

    2011-10-01

    In 2008 we began a three-year NASA Earth Science Technology Office (ESTO) funded Instrument Incubator Program (IIP) focused on technology development for the Lidar Surface Topography (LIST) mission. The LIST mission is one of the Earth Science Decadal Survey missions recommended to NASA by the National Research Council (NRC). Our IIP objective is to demonstrate the measurement approach and key technologies needed for a highly efficient swath mapping lidar to meet the goals of the LIST mission. To demonstrate the concept we are developing the Airborne LIST Simulator (A-LISTS) instrument. In this paper we summarize the A-LISTS instrument characteristics and the approaches we are using to advance lidar capabilities and reduce risks for LIST.

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

    SciTech Connect

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

    2011-08-31

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

  6. The Syrtis Major volcanic province, Mars: Synthesis from Mars Global Surveyor data

    E-print Network

    Head III, James William

    The Syrtis Major volcanic province, Mars: Synthesis from Mars Global Surveyor data H. Hiesinger] We investigated the geology, stratigraphy, morphology, and topography of Syrtis Major, one of the large Hesperian-aged volcanic provinces on Mars. New data from the Mars Global Surveyor (MGS

  7. Pre-LGM Northern Hemisphere ice sheet topography

    NASA Astrophysics Data System (ADS)

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

    2013-10-01

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

  8. Fractional snow-covered area parameterization over complex topography

    NASA Astrophysics Data System (ADS)

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

    2014-08-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Rosenburg, Margaret A.

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

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

    NASA Astrophysics Data System (ADS)

    Polkowski, Marcin; Majorowicz, Jacek; Grad, Marek

    2013-04-01

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

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

    PubMed

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

    2014-05-14

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

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

    NASA Astrophysics Data System (ADS)

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

    Japanese lunar orbiting mission SELENE Selenological and Engineering Explorer incorporates three selenodetic missions by RISE group Researches In SElenodesy in National Astronomical Observatory of Japan The first is Laser Altimeter LALT which measures the distance between the main orbiter and the lunar surface for the lunar topography Second is four-way range-rate measurement by using a sub-satellite RSAT and the last is differential VLBI measurement of the two sub-satellites which are equipped with radio sources of S and X bands VRAD SELENE is scheduled to be launched in summer 2007 and various tests has been carried out LALT incorporates Q-switched Nd YAG laser system which transmits laser pulses per 1 second with 1064nm in wavelength 17nsec time width and 100mJ energy Q-switch consists of LiNbO 3 Pockels cell The output beam divergence is 0 4 mrad after passing through the 7 3cm Galileo refractor Beam spot size on lunar surface is typically 40m when main orbiter altitude is 100km Range accuracy between SELENE orbiter and the lunar surface is pm 5m The range data are transformed to the topography of the moon with the aid of position and attitude data of the SELENE orbiter The foot print spacing will be 1 6 km in the equatorial region after 1 yr mission period In the pole regions the distance of ranged position on the moon will be less than 300m and the mean distance will be 100m Mission objectives of LALT are summarized as making a low degree model of lunar figure and construction of lunar global topographic map with

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

    PubMed Central

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

    2013-01-01

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

  14. A Link between Adolescent Nicotine Metabolism and Smoking Topography

    PubMed Central

    Moolchan, Eric T.; Parzynski, Craig S.; Jaszyna-Gasior, Maria; Collins, Charles C.; Leff, Michelle K.; Zimmerman, Debra L.

    2009-01-01

    Adult slow nicotine metabolizers have lower smoke exposure, carbon monoxide levels, and plasma nicotine levels than normal and fast metabolizers. Emerging evidence suggests nicotine metabolism influences smoking topography. This study investigated the association of nicotine metabolism (the ratio of plasma 3-hydroxycotinine to cotinine; 3OHCOT/COT) with smoking topography in adolescent smokers (N=85, 65% female, 68% European American, mean age 15.3 ± 1.2, mean cigarettes per day (CPD) 18.5 ± 8.5, mean Fagerström Test for Nicotine Dependence (FTND) 7.0 ± 1.2) presenting for a nicotine replacement therapy trial. Measures obtained included puff volume, inter-puff interval, number of puffs, puff duration, and puff velocity. Linear regression analysis controlling for hormonal contraception use showed that 3OHCOT/COT ratios predicted mean puff volume in the overall sample (t = 2.126, p = .037, adjusted R2 = .067). After gender stratification, faster metabolism predicted higher mean puff volume (t = 2.81, p = .009, adjusted R2 = .192) but fewer puffs (t = ?3.160, p=0.004, adjusted R2 = .237) and lower mean puff duration (t = ?2.06, p = .048, adjusted R2 = .101) among boys only, suggesting that as nicotine metabolism increases, puff volume increases but puffing frequency decreases. No significant relationships were found between nicotine metabolism and total puff volume, mean puff duration, inter-puff interval, or puff velocity. If confirmed in a broader sample of adolescent smokers, these findings suggest that, as among dependent adult smokers, rate of metabolism among adolescent boys is linked to select parameters of puffing behavior that may impact cessation ability. PMID:19423535

  15. Fractional snow-covered area parameterization over complex topography

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

    Fractional snow-covered area (SCA) is a key parameter in large-scale hydrological, meteorological and regional 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 SCA based on a new subgrid parameterization for the standard deviation of snow depth over complex topography. Highly resolved snow depth data at the 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 one 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 (SCD) curves were derived for a broad range of coefficients of variations. The most accurate closed form fit resembled an existing fractional SCA parameterization. By including the subgrid parameterization for the standard deviation of snow depth, we extended the fractional SCA parameterization for topographic influences. For all domain sizes we obtained errors lower than 10% between measured and parameterized SCA.

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

    USGS Publications Warehouse

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

    2007-01-01

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

  17. Plasma molding over surface topography: Energy and angular distribution of ions extracted out of large holes

    E-print Network

    Economou, Demetre J.

    Plasma molding over surface topography: Energy and angular distribution of ions extracted out of large holes Chang-Koo Kim and Demetre J. Economoua) Plasma Processing Laboratory, Department of Chemical November 2001 Plasma molding over surface topography was investigated by measuring the energy and angular

  18. Modeling the dynamic component of the geoid and topography of Venus

    E-print Network

    Cerveny, Vlastislav

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

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

    E-print Network

    Steinberger, Bernhard

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

  20. The Threat-Victim Table - A Security Prioritisation Framework For Diverse WLAN Network Topographies

    Microsoft Academic Search

    Jonny Milliken; Alan Marshall

    2010-01-01

    At present there is no common means for establishing the security performance of wireless local area networks (WLANs) against threats. Furthermore, there has been little investigation into whether security performance is reliant on network topography. Consequently this paper advocates that for a range of WLAN infrastructure topographies (home, enterprise & open-access) there can be significant diversity in terms of resources,

  1. Gold Mesostructures with Tailored Surface Topography and Their Self-Assembly Arrays

    E-print Network

    Wang, Wei Hua

    , sea urchin-like, surface topography, self-assembly, SERS S urface-enhanced Raman scattering (SERSGold Mesostructures with Tailored Surface Topography and Their Self-Assembly Arrays for Surface-Enhanced Raman Spectroscopy Jixiang Fang,*,,§ Shuya Du, Sergei Lebedkin,§ Zhiyuan Li, Robert Kruk,§ Manfred

  2. Observation of chirality domains in terbium by polarized neutron diffraction topography

    E-print Network

    Paris-Sud XI, Université de

    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

  3. APPLICATION DE LA TOPOGRAPHIE PAR DIFFRACTION DES RAYONS X A L'TUDE DES MTAUX

    E-print Network

    Boyer, Edmond

    311. APPLICATION DE LA TOPOGRAPHIE PAR DIFFRACTION DES RAYONS X A L'ÉTUDE DES MÉTAUX Par G On rappelle le principe des différentes méthodes de topographie par diffraction des rayons X : méthode de Berg améliorations à apporter dans le cadre de l'appareillage : tubes à rayons X plus puissants, intensificateurs d

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

    Microsoft Academic Search

    Lyndon F. Cooper

    2000-01-01

    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

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

    E-print Network

    Zabaras, Nicholas J.

    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 deformation and heat transfer at the mold/solid-shell interface during the early stages of Aluminum

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

    ERIC Educational Resources Information Center

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

    2008-01-01

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

  7. Topography as a major factor in the development of arcuate thrust belts: insights from sandbox experiments

    Microsoft Academic Search

    F. O. Marques; P. R. Cobbold

    2002-01-01

    We have used sandbox experiments to investigate and to illustrate the effects of topography upon the development of arcuate thrust belts. In experiments where a sand pack shortened and thickened in front of an advancing rectilinear piston, the geometry of the developing thrust wedge was highly sensitive to variations in surface topography. In the absence of erosion and sedimentation, the

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

    E-print Network

    Miami, University of

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

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

    E-print Network

    Dauxois, Thierry

    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

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

    USGS Publications Warehouse

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

    1985-01-01

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

  11. The effect of atmospheric CO 2 and ice sheet topography on LGM climate

    Microsoft Academic Search

    S. J. Kim

    2004-01-01

    The role of reduced atmospheric CO 2 concentration and ice sheet topography plus its associated land albedo on the LGM climate is investigated using a coupled atmosphere-ocean-sea ice climate system model. The surface cooling induced by the reduced CO 2 concentration is larger than that by the ice sheet topography plus other factors by about 30% for the surface air

  12. Author's personal copy 10.05 Gravity and Topography of the Terrestrial Planets

    E-print Network

    Wieczorek, Mark

    Author's personal copy 10.05 Gravity and Topography of the Terrestrial Planets M. A. Wieczorek of the gravitational fields and topography of the terrestrial planets. These advances are intimately related precise ways to investigate the subsurface structure of a planet is through the analy- sis of seismic

  13. The surface topography of a magnetic fluid: a quantitative comparison between experiment and numerical simulation

    Microsoft Academic Search

    Christian Gollwitzer; Gunar Matthies; Reinhard Richter; Ingo Rehberg; Lutz Tobiska

    2007-01-01

    The normal field instability in magnetic liquids is investigated experimentally by means of a radioscopic technique which allows a precise measurement of the surface topography. The dependence of the topography on the magnetic field is compared to results obtained by numerical simulations via the finite-element method. Quantitative agreement has been found for the critical field of the instability, the scaling

  14. In need of combined topography and bathymetry DEM

    NASA Astrophysics Data System (ADS)

    Kisimoto, K.; Hilde, T.

    2003-04-01

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

  15. Harmonic and statistical analyses of the gravity and topography of Vesta

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

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

    E-print Network

    Nikurashin, Maxim

    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 ...

  18. 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

    Ezer,Tal

    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

  19. Anomalous Accretionary Margin Topography Formed By Repeated Earthquakes

    NASA Astrophysics Data System (ADS)

    Furlong, Kevin P.

    2014-05-01

    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.

  20. Signatures of Asymmetric Topography: From Measurements to Mechanisms

    NASA Astrophysics Data System (ADS)

    Richardson, P. W.; Perron, T.; Miller, S. R.

    2011-12-01

    Some landscapes exhibit the intriguing topographic characteristic that slopes facing a certain direction are systematically steeper than slopes facing other directions, even when there is no bias introduced by bedrock structure. Two fundamentally different mechanisms have been proposed to explain microclimate-induced asymmetry in regions with semi-arid to Mediterranean climates. One hypothesis is that asymmetric aggradation of sediments in a valley bottom forces a river flowing through the valley to migrate away from the side of the valley that experiences faster aggradation, leading to undercutting of the opposite bank and steepening of the adjacent hillslope. The other hypothesis is that differences in the efficiency of erosion processes between pole-facing and equator-facing slopes directly cause topographic asymmetry. Both hypotheses rely on the presence of different microclimates on opposing slopes. Thus, identifying the specific mechanism or mechanisms controlling the topographic asymmetry will be a large step toward understanding the interaction between climate and topography. To accomplish this goal, it is critical to identify measurable characteristics of asymmetric topography - including, but not limited to, the asymmetry in slopes - that may be unique signatures of specific erosional mechanisms. We have developed methods to measure asymmetry in hillslope gradient, valley spacing, and low-order valley depth (first or second order) on opposing slopes. We analyzed fourteen contiguous drainage basins ranging in size from 1.6 km2 to 16.1 km2 at Gabilan Mesa, CA. Strong topographic asymmetry and a simple underlying lithology consisting of moderately consolidated sedimentary rocks have made Gabilan Mesa a popular site for studying the cause of topographic asymmetry, yet no consensus exists on the mechanism or mechanisms causing the asymmetry. We found that the north-facing hillslopes are over 20% steeper than south-facing hillslopes and that low-order valleys on south-facing hillslopes are generally more deeply incised than low-order valleys on north-facing hillslopes. In addition to making the asymmetry measurements, we test whether topographic asymmetry exhibits dependence on distance from the channel head of the main valley bounded by the asymmetric slopes-a relationship that has been predicted to arise if lateral stream undercutting is the primary cause of valley asymmetry. Preliminary numerical modeling results suggest that particular combinations of asymmetries in these measured quantities may be diagnostic of different hypothesized mechanisms for generating the asymmetry. Thus, our measurements should provide a basis for more definitive tests of these conflicting hypotheses.

  1. Quantifying Characteristic Length Scales and Patterns in Topography

    NASA Astrophysics Data System (ADS)

    Schmiddunser, Matthias; Ehlers, Todd A.

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.; Cassini Radar Team

    2011-12-01

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

  3. Printability of topography in alternating aperture phase-shift masks

    NASA Astrophysics Data System (ADS)

    Philipsen, Vicky; Jonckheere, Rik

    2004-12-01

    Alternating aperture phase-shift mask (AAPSM) technology in combination with conventional illumination enables the imaging needed in the 65nm node and beyond, thanks to its high image contrast and small mask error factor (MEF). It is a known point of attention that AAPSM topography induces an image intensity imbalance between the light propagating through the zero and pi-shifted space. There are several ways to compensate for such imbalance in the mask making process. The most common approaches are applying an undercut or a bias of the pi-shifted space. The guaranteed quartz etch depth of the pi-shifted space through pitch is another challenge in the mask making process of an AAPSM. This paper reports on the methodology to evaluate the mask making quality of AAPSM for both 193nm and 157nm lithography through printability. For this purpose rigorous electro-magnetic field simulations through the 3D mask topography using Solid-CM (software from Sigma-C) are performed. The parameter for the quantification of the image imbalance is the difference between the measured width of neighbouring zero and pi-shifted spaces on the wafer print. As a first step in the methodology the amount of undercut or bias applied on the mask is deduced from the correlation between the experimentally measured and simulated space difference. Once the amount of undercut or bias is known, the phase error for the evaluated structure is estimated by evaluating the through focus behaviour of the space difference. This gives an indication of the quality of the etch process through pitch during mask making. For the 193nm lithography the wafers are exposed on an ASML PAS5500/1100 ArF scanner working with a 0.75NA projection lens. The 157nm AAPSM masks are printed with an ASML Micrascan VII equipped with a 0.75NA projection lens. The wafers and masks are evaluated on a top-down mask-compatible CD-SEM (KLA-Tencor 8250XR).

  4. UNIVERSITYOF HAWAI'I lIl3RARY INTERNAL TIDE SCATTERING AT M1DOCEAN TOPOGRAPHY

    E-print Network

    Luther, Douglas S.

    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

  5. A fractal interpretation of topography and geoid spectra on the earth, moon, Venus, and Mars

    NASA Technical Reports Server (NTRS)

    Turcotte, Donald L.

    1987-01-01

    Global spectra are available for topography and geoid on the earth, Venus, Mars, and the moon. If the spectral energy density has a power law dependence on wave number, a fractal is defined. The topography spectrum for the earth is a well-defined fractal with D = 1.5; this corresponds to Brown noise with the amplitude proportional to the wavelength. Although there is more scatter for the other planetary bodies, the data for Mars and the moon correlate well with the data for the earth. Venus topography also exhibits a Brown noise behavior but with a smaller amplitude. The power law dependence of the earth's geoid is known as Kaula's law. It is shown that uncompensated Brown topography gives a geoid with a power law dependence that is in quite good agreement with Kaula's law. However, the required amplitude is only 8 percent of the observed topography. A similar result is found for the other bodies, with the ratio of the amplitude of topography required to explain the geoid to the observed topography increasing to 72 percent for the moon.

  6. Functional topography of primary emotion processing in the human cerebellum.

    PubMed

    Baumann, Oliver; Mattingley, Jason B

    2012-07-16

    The cerebellum has an important role in the control and coordination of movement. It is now clear, however, that the cerebellum is also involved in neural processes underlying a wide variety of perceptual and cognitive functions, including the regulation of emotional responses. Contemporary neurobiological models of emotion assert that a small set of discrete emotions are mediated through distinct cortical and subcortical areas. Given the connectional specificity of neural pathways that link the cerebellum with these areas, we hypothesized that distinct sub-regions of the cerebellum might subserve the processing of different primary emotions. We used functional magnetic resonance imaging (fMRI) to identify neural activity patterns within the cerebellum in 30 healthy human volunteers as they categorized images that elicited each of the five primary emotions: happiness, anger, disgust, fear and sadness. In support of our hypothesis, all five emotions evoked spatially distinct patterns of activity in the posterior lobe of the cerebellum. We also detected overlaps between cerebellar activations for particular emotion categories, implying the existence of shared neural networks. By providing a detailed map of the functional topography of emotion processing in the cerebellum, our study provides important clues to the diverse effects of cerebellar pathology on human affective function. PMID:22465459

  7. Hydrodynamic modeling for river delta salt marshes using lidar topography

    NASA Astrophysics Data System (ADS)

    Hodges, Ben R.

    2014-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

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

    NASA Technical Reports Server (NTRS)

    2008-01-01

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

    This movie shifts from a global zoom indicating the Phoenix landing area on Mars to a topographical map indicating relative elevations in the landing region. The elevations could affect wind patterns at the site.

    In particular, Phoenix is in a broad, shallow valley. The edge of the valley, about 150 meters (500 feet) above the floor, may provide enough of a slope to the east of Phoenix to explain winds coming from the east during nights at the site. Cooler, denser air could be sinking down the slope and toward the lander.

    Atmospheric scientists on the Phoenix team are analyzing wind patterns to distiguish effects of nearby topography from larger-scale movement of the atmosphere in the polar region.

    The elevation information for this topographical mapping comes from the Mars Orbiter Laser Altimeter on NASA's Mars Global Surveyor orbiter. The blue-coded area is the valley floor. Orange and yellow indicate relatively higher elevations.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver. JPL managed the Mars Global Surveyor mission for the NASA Science Mission Directorate.

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

    PubMed Central

    Grégoire, Charles

    1957-01-01

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

  11. Ultrastructural basement membrane topography of the bladder epithelium.

    PubMed

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

    2003-10-01

    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 was developed to remove the epithelium while preserving the underlying basement membrane, and tissues were evaluated by immunohistochemistry and scanning electron microscopy (SEM). Detailed measurements were made of stereo SEM images to quantitatively define topographic features. Measurements made from multiple SEM images of bladder basement membrane provided the following values for topographic features: mean feature height, 178+/-57 nm; mean fiber diameters, 52+/-28 nm; mean pore diameter, 82+/-49 nm; and mean interpore distance (center to center), 127+/-54 nm. These dimensions are similar to those reported previously for basement membranes of other species and anatomical locations. This information provides a rational basis for design of nanostructured biomaterials to produce composite grafts for repair or replacement of segments of the urinary tract. PMID:14574540

  12. Accuracy of the PAR corneal topography system with spatial misalignment.

    PubMed

    Belin, M W; Zloty, P

    1993-01-01

    The PAR Corneal Topography System is a computerized corneal imaging system which uses close-range raster photogrammetry to measure and produce a topographic map of the corneal surface. Raster photogrammetry is a standard method of extracting object information by projecting a known pattern onto an object and recording the distortion when viewed from an oblique angle. Unlike placido disc based videokeratoscopes, the PAR system requires neither a smooth reflective surface nor precise spatial alignment for accurate imaging. We studied both the accuracy of the system with purposeful misalignment (defocusing) of the test object and determined the ability to image freshly deepithelialized, keratectomized, and photoablated corneas. The PAR system was both accurate and reproducible in imaging calibrated spheres within a defined zone in space. Whole cadaver eyes were imaged both before and immediately after removal of the epithelium, lamellar keratectomy, and laser photoablation. The system demonstrated the ability to image irregular, deepithelialized, and keratectomized corneas. The ability to maintain accuracy without precise alignment and the facility to image freshly deepithelialized and keratectomized corneas may make the system suitable for intraoperative refractive monitoring. PMID:8453756

  13. Crustal structure of Mars from gravity and topography

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

    Mars Orbiter Laser Altimeter (MOLA) topography and gravity models from 5 years of Mars Global Surveyor (MGS) spacecraft tracking provide a window into the structure of the Martian crust and upper mantle. We apply a finite-amplitude terrain correction assuming uniform crustal density and additional corrections for the anomalous densities of the polar caps, the major volcanos, and the hydrostatic flattening of the core. A nonlinear inversion for Moho relief yields a crustal thickness model that obeys a plausible power law and resolves features as small as 300 km wavelength. On the basis of petrological and geophysical constraints, we invoke a mantle density contrast of 600 kg m-3; with this assumption, the Isidis and Hellas gravity anomalies constrain the global mean crustal thickness to be >45 km. The crust is characterized by a degree 1 structure that is several times larger than any higher degree harmonic component, representing the geophysical manifestation of the planet's hemispheric dichotomy. It corresponds to a distinction between modal crustal thicknesses of 32 km and 58 km in the northern and southern hemispheres, respectively. The Tharsis rise and Hellas annulus represent the strongest components in the degree 2 crustal thickness structure. A uniform highland crustal thickness suggests a single mechanism for its formation, with subsequent modification by the Hellas impact, erosion, and the volcanic construction of Tharsis. The largest surviving lowland impact, Utopia, post-dated formation of the crustal dichotomy. Its crustal structure is preserved, making it unlikely that the northern crust was subsequently thinned by internal processes.

  14. Crater topography on Titan: implications for landscape evolution

    USGS Publications Warehouse

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

  16. Topography of Vesta from Dawn FC stereo images

    NASA Astrophysics Data System (ADS)

    Preusker, F.; Scholten, F.; Matz, K.-D.; Roatsch, T.; Jaumann, R.; Raymond, C. A.; Russell, C. T.

    2012-09-01

    The Dawn mission has completed its Survey and High Altitude Mapping Orbit (HAMO) phases at Vesta and is currently in its Low Altitude Mapping Orbit (LAMO) [1]. From the Survey orbit (altitude ~2,700 km) the Dawn Framing Camera (FC) [2] acquired 1,179 clear filter images with a mean image resolution of 256 m/pixel whereas from the HAMO orbit (~700 km altitude) there are 2,674 clear filter images with a mean resolution of 63 m/pixel. In both mapping phases the surface was imaged several times under similar illumination conditions (Sun elevation and azimuth), but different viewing conditions (by tilting the spacecraft). This allows to analyze the images stereoscopically and to construct stereo topographic maps. The topography is particularly important, because it is essential for derivation of physical properties of Vesta, precise ortho-image registration, mosaicking, and map generation of monochrome/color FC images and VIR images, quantitative geomorphologic analysis, and precise photometric analysis (from detailed local surface inclination).

  17. Functional topography: multidimensional scaling and functional connectivity in the brain.

    PubMed

    Friston, K J; Frith, C D; Fletcher, P; Liddle, P F; Frackowiak, R S

    1996-01-01

    In neuroimaging, functional mapping usually implies mapping function into an anatomical space, for example, using statistical parametric mapping to identify activation foci, or the characterization of distributed changes with spatial modes (eigenimages or principal components) (Friston et al., 1993a). This article is about a complementary approach, namely, mapping anatomy into a functional space. We describe a simple variant of multidimensional scaling (principal coordinates analysis; Gower, 1966) that uses functional connectivity as its metric. The scaling transformation maps anatomy into a functional space. The topography, or proximity relationships, in this space embody the functional connectivity among brain regions. The higher the functional connectivity, the closer the regions. Functional connectivity is defined here as the correlation between remote neurophysiological events. The technique represents a descriptive characterization of anatomically distributed changes in the brain that reveals the structure of corticocortical interactions in terms of functional correlations. To illustrate the approach we have analyzed data from normal subjects and schizophrenic patients obtained with PET during the performance of word generation tasks. In particular, we focus on prefrontotemporal integration in normal subjects and show that, in schizophrenia, the left temporal regions and prefrontal cortex evidence abnormal functional connectivity. PMID:8670646

  18. Topography of the retinal ganglion cell layer of Xenopus.

    PubMed Central

    Graydon, M L; Giorgi, P P

    1984-01-01

    Cell distribution in the retinal ganglion cell layer of Xenopus laevis was studied by electron microscopy and the retinal wholemount method. Unlike the familiar stratification of the retina, the ganglion cell perikarya and their axons were localised in the same layer, but strictly segregated in alternate rows converging in a radial pattern on the optic disc. Rows of perikarya (retinal cords) were two to ten cells wide and clearly defined for a little more than half the distance between the optic disc and the ora serrata. Detailed analysis of 25% of the retinal surface showed higher cell density (about 3500 cells/mm2) in the centrodorsal region than in the periphery (about 2000 cells/mm2). The higher density regions represent a weak visual streak having no nasotemporal asymmetry. After staining with cresyl violet, the majority of cells appeared to be small (10 micron diameter) with very little Nissl substance. The cytoplasm was scant; this was confirmed by electron microscopy. The difference between the total cell count (68470 +/- 7360) and the total axon count in the optic nerve (Wilson, 1971) suggests a population of 15% non-ganglionic cells (glia and amacrine cells) in the retinal ganglion cell layer. Retinal ganglion cell topography in Xenopus may have relevance to studies on retinal growth and retinotopy. The functional significance of the weak visual streak in Xenopus is consistent with a limited need for visual acuity. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:6206043

  19. The Effect of Mountain Topography on Local Atmospheric Flows (Invited)

    NASA Astrophysics Data System (ADS)

    Parlange, M. B.; Higgins, C. W.; Diebold, M.; Lehning, M.

    2009-12-01

    Land atmosphere interaction within an alpine catchment is a driving force behind the physical processes of latent heat transport, and evaporative transport. Such physical processes are dependent on the flow features created by the topography itself. For example, H.W. Lewis et al 2008 observed persistent flows along the Gaudergrat ridge independent of the synoptic atmospheric conditions. In this work, Large Eddy Simulations (LES) of an alpine region that includes the Gaudergrat ridge are performed and analyzed to further investigate these persistent ridge flows. First, the LES code, using the immersed boundary method, is validated against wind tunnel data of flow over a steep three dimensional Gaussian hill. Here, comparisons are favorable in both flow velocity and variance profiles. The validated LES code is then used to perform high resolution simulations of the atmospheric flow over an alpine area located in eastern Switzerland (the Gaudergrat ridge). The simulations reveal that the persistent ridge flows are a result of the local pressure fields created by asymmetries in the mountain structure.

  20. Discriminant analysis of functional optical topography for schizophrenia diagnosis

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Smith, David E.

    2002-01-01

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

  2. Determining Titan surface topography from Cassini SAR data

    USGS Publications Warehouse

    Stiles, Bryan W.; Hensley, Scott; Gim, Yonggyu; Bates, David M.; Kirk, Randolph L.; Hayes, Alex; Radebaugh, Jani; Lorenz, Ralph D.; Mitchell, Karl L.; Callahan, Philip S.; Zebker, Howard; Johnson, William T.K.; Wall, Stephen D.; Lunine, Jonathan I.; Wood, Charles A.; Janssen, Michael; Pelletier, Frederic; West, Richard D.; Veeramacheneni, Chandini

    2009-01-01

    A technique, referred to as SARTopo, has been developed for obtaining surface height estimates with 10 km horizontal resolution and 75 m vertical resolution of the surface of Titan along each Cassini Synthetic Aperture Radar (SAR) swath. We describe the technique and present maps of the co-located data sets. A global map and regional maps of Xanadu and the northern hemisphere hydrocarbon lakes district are included in the results. A strength of the technique is that it provides topographic information co-located with SAR imagery. Having a topographic context vastly improves the interpretability of the SAR imagery and is essential for understanding Titan. SARTopo is capable of estimating surface heights for most of the SAR-imaged surface of Titan. Currently nearly 30% of the surface is within 100 km of a SARTopo height profile. Other competing techniques provide orders of magnitude less coverage. We validate the SARTopo technique through comparison with known geomorphological features such as mountain ranges and craters, and by comparison with co-located nadir altimetry, including a 3000 km strip that had been observed by SAR a month earlier. In this area, the SARTopo and nadir altimetry data sets are co-located tightly (within 5-10 km for one 500 km section), have similar resolution, and as expected agree closely in surface height. Furthermore the region contains prominent high spatial resolution topography, so it provides an excellent test of the resolution and precision of both techniques.

  3. Crater Topography on Titan: Implications for Landscape Evolution

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1997-01-01

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

  6. Development of material measures for performance verifying surface topography measuring instruments

    NASA Astrophysics Data System (ADS)

    Leach, Richard; Giusca, Claudiu; Rickens, Kai; Riemer, Oltmann; Rubert, Paul

    2014-04-01

    The development of two irregular-geometry material measures for performance verifying surface topography measuring instruments is described. The material measures are designed to be used to performance verify tactile and optical areal surface topography measuring instruments. The manufacture of the material measures using diamond turning followed by nickel electroforming is described in detail. Measurement results are then obtained using a traceable stylus instrument and a commercial coherence scanning interferometer, and the results are shown to agree to within the measurement uncertainties. The material measures are now commercially available as part of a suite of material measures aimed at the calibration and performance verification of areal surface topography measuring instruments.

  7. The Mystery of the Mars North Polar Gravity-Topography Correlation(Or Lack Thereof)

    NASA Technical Reports Server (NTRS)

    Phillips, R. J.; Sjogren, W. L.; Johnson, C. L.

    1999-01-01

    Maps of moderately high resolution gravity data obtained from the Mars Global Surveyor (MGS) gravity calibration orbit campaign and high precision topography obtained from the Mars Orbiter Laser Altimeter (MOLA) experiment reveal relationships between gravity and topography in high northern latitudes of Mars. Figure 1 shows the results of a JPL spherical harmonic gravity model bandpass filtered between degrees 6 and 50 contoured over a MOLA topographic image. A positive gravity anomaly exists over the main North Polar cap, but there are at least six additional positive gravity anomalies, as well as a number of smaller negative anomalies, with no obvious correlation to topography. Additional information is contained in the original extended abstract.

  8. Leveraging High Resolution Topography for Education and Outreach: Updates to OpenTopography to make EarthScope and Other Lidar Datasets more Prominent in Geoscience Education

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2000-01-01

    The Carrizozo flow in south-central New Mexico was examined to obtain detailed topography for a long basaltic lava flow. This information will be helpful in evaluating emplacement models for long lava flows.

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

    E-print Network

    Assimaki, Dominic, 1975-

    2004-01-01

    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 ...

  12. Large Volcanic Edifices and Rises on Venus: The Benefits of Improved Topography and Gravity Data

    NASA Astrophysics Data System (ADS)

    McGovern, P. J.

    2014-05-01

    Venus is a volcanological laboratory, replete with edifices and rises that offer potentially deep insights into its evolution. However, this potential can only be realized with improved topography and gravity data, requiring a new orbital mission.

  13. Investigating Karst topography and its connection to SE Minnesota sinkholes and cave formations.

    NSDL National Science Digital Library

    Anne Feist NRHEG Public School New Richland, MN

    This activity is a field investigation where students will be able to observe sinkholes located in the southeastern Minnesota area and a cave system in Forestville State Park which will assist them in defining Karst topography.

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

    NASA Technical Reports Server (NTRS)

    Gaskell, Robert W.; Barnouin-Jha, O. S.; Scheeres, D. J.; Mukai, T.; Hirata, N.; Abe, S.; Saito, J.; Hashimoto, T.; Ishiguro, M.; Kubota, T.

    2006-01-01

    This viewgraph document reviews the topography of the Itokawa asteroid. It summarizes some of the relevant information about the asteroid, and how using the imaging from Hayabusa and LIDAR data, a topographic image of Itokawa was derived.

  15. The effect of topography on the wavelet response of seismic arrays

    E-print Network

    Al-Shuhail, Abdullatif Abdulrahman

    1993-01-01

    The Effect of Topography on the Wavelet Response of Seismic Arrays. (December 1993) Abdullatif Abdulrahman Al-Shuhail, B. S. , King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia Chair of Advisory Committee: Dr. Anthony F. Gangi...

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

    E-print Network

    Beier, Paul

    - 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

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

    E-print Network

    Echeverri Mondragón, Paula

    2006-01-01

    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] ...

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

    E-print Network

    Peacock, Thomas

    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 ...

  19. Simulated Global Atmospheric Dust Distribution: Sensitivity to Regional Topography, Geomorphology, and Hydrology

    E-print Network

    Zender, Charles

    Simulated Global Atmospheric Dust Distribution: Sensitivity to Regional Topography, Geomorphology for predicting future trends in dust production. We identify three related geomorphologic and hydrologic to regional surface geomorphology and runoff on large spatial scales. Satellite observations show

  20. Modeling surface winds in mountainous catchments as a function of topography and vegetation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to develop accurate distributed hydrological models, spatially accurate meteorological forcing fields are required. In mountainous basins, elevation and topography strongly influence temperature, precipitation, vapor pressure, and wind. At the watershed scale, temperature, precipitation, ...

  1. Exact three-dimensional spectral solution to surface-groundwater interactions with arbitrary surface topography

    USGS Publications Warehouse

    Worman, A.; Packman, A.I.; Marklund, L.; Harvey, J.W.; Stone, S.H.

    2006-01-01

    It has been long known that land surface topography governs both groundwater flow patterns at the regional-to-continental scale and on smaller scales such as in the hyporheic zone of streams. Here we show that the surface topography can be separated in a Fourier-series spectrum that provides an exact solution of the underlying three-dimensional groundwater flows. The new spectral solution offers a practical tool for fast calculation of subsurface flows in different hydrological applications and provides a theoretical platform for advancing conceptual understanding of the effect of landscape topography on subsurface flows. We also show how the spectrum of surface topography influences the residence time distribution for subsurface flows. The study indicates that the subsurface head variation decays exponentially with depth faster than it would with equivalent two-dimensional features, resulting in a shallower flow interaction. Copyright 2006 by the American Geophysical Union.

  2. Modeling Floods in Athabasca Valles, Mars, Using CTX Stereo Topography

    NASA Astrophysics Data System (ADS)

    Dundas, C. M.; Keszthelyi, L. P.; Denlinger, R. P.; Thomas, O. H.; Galuszka, D.; Hare, T. M.; Kirk, R. L.; Howington-Kraus, E.; Rosiek, M.

    2012-12-01

    Among the most remarkable landforms on Mars are the outflow channels, which suggest the occurrence of catastrophic water floods in the past. Athabasca Valles has long been thought to be the youngest of these channels [1-2], although it has recently become clear that the young crater age applies to a coating lava flow [3]. Simulations with a 2.5-dimensional flood model have provided insight into the details of flood dynamics but have also demonstrated that the Digital Elevation Model (DEM) from the Mars Orbiter Laser Altimeter (MOLA) Mission Experiment Gridded Data Records includes significant artifacts at this latitude at the scales relevant for flood modeling [4]. In order to obtain improved topography, we processed stereo images from the Context Camera (CTX) of the Mars Reconnaissance Orbiter (MRO) using methods developed for producing topographic models of the Moon with images from the Lunar Reconnaissance Orbiter Camera, a derivative of the CTX camera. Some work on flood modeling with CTX stereo has been published by [5], but we will present several advances, including corrections to the published CTX optical distortion model and improved methods to combine the stereo and MOLA data. The limitations of current methods are the accuracy of control to MOLA and the level of error introduced when the MRO spacecraft is not in a high-stability mode during stereo imaging, leading to jitter impacting the derived topography. Construction of a mosaic of multiple stereo pairs, controlled to MOLA, allows us to consider flow through the cluster of streamlined islands in the upper part of the channel [6], including what is suggested to be the best example of flood-formed subaqueous dunes on Mars [7]. We will present results from running a flood model [4, 8] through the high-resolution (100 m/post) DEM covering the streamlined islands and subaqueous dunes, using results from a lower-resolution model as a guide to the inflow. By considering a range of flow levels below estimated peak flow, we can examine the flow behavior at the site of the apparent subaqueous dunes and, in particular, assess whether the flow in this area is uniquely conducive to the formation of such bedforms [e.g., 9]. [1] Berman D. C. and Hartmann W. K. (2002) Icarus 159, 1-17. [2] Burr D. M. et al. (2002) Icarus 159, 53-73. [3] Jaeger W. L. et al. (2010) Icarus 205, 230-243. [4] Keszthelyi L. P. et al. (2007) GRL 34, L21206. [5] McIntyre et al. (2012) JGR 117, E03009. [6] Burr D. (2005) Geomorphology 69, 242-252. [7] Burr D. M. et al. (2004) Icarus 171, 68-83. [8] Denlinger R. P. and O'Connell D. R. H. (2008) J. Hyd. Eng. 134, 1590-1602. [9] Kleinhans M. G. (2005) JGR 110, E12003.

  3. Oligocene Provenance, Drainage Morphology, and Topography of the Nevadaplano

    NASA Astrophysics Data System (ADS)

    Cassel, E. J.; Henry, C. D.; Graham, S. A.; Chamberlain, C. P.; Grove, M.

    2011-12-01

    Debate surrounds the origin, uplift, and evolution of the northern Sierra Nevada and western Basin and Range. Many consider the Late Cretaceous to early Cenozoic Sierra to have formed the western edge of a high elevation plateau that covered much of what is now Nevada. The topography, extent, and drainage of this plateau remain uncertain. We integrate local paleovalley morphology and alluvial conglomerate stratigraphy with regional assessments of sediment and volcanic provenance and paleo-elevations across the proposed ancestral "Nevadaplano" to gain a better understanding of the early Cenozoic geomorphic evolution of the region, and to assess the possible tectonic and climatic drivers for that evolution. A sequence of Oligocene rhyolitic ignimbrites is preserved from eastern Nevada to the western foothills of the modern Sierra, commonly overlying a basal alluvial/fluvial coarse sand- to cobble-size conglomerate. The stratigraphy and provenance of these units, based on clast composition, detrital zircon and 40Ar/39Ar geochronology, and TREE geochemistry, demonstrates the presence of an active westward-draining fluvial system in the late Eocene to early Oligocene. Although dominated by Mesozoic batholith sources, detrital zircon populations from fluvial deposits in the northern Sierra contain 2-20% zircon grains with U-Pb ages from 42.7 to 33.0 Ma, which were likely sourced from Eocene volcanic rocks in northern Nevada, and 5-30% Precambrian zircon grains, reflecting derivation from basement metamorphic belts of the Sierra, as well as possible contributions from Nevada. Hydrated volcanic glass from overlying ignimbrites was used as a proxy for ?D of Oligocene meteoric water, which reflects the effect of ancient topography on precipitation. ?D decreases gradually from west to east across what is now northern Nevada, although at a significantly lower gradient than Oligocene ?D across the Sierra. ?D of volcanic glass across Nevada decreases from values ranging from -139% ± 3% to -146% ± 3% at locations that are now ~180 km east of the Great Valley, to values ranging from -153% ± 3% to -167% ± 3% at locations ~470 km to the east (near Carlin). This 7-28 ± 3% decrease in Oligocene ?D occurs over less distance than a similar magnitude isotopic change in modern meteoric waters or in 2-5.5 Ma old hydrated volcanic glass, but this decrease does not necessitate orographic fractionation. These data show a significant reduction in the rate of increase of paleo-elevation with distance, in comparison with the region to the west (now the Sierra Nevada), and may reflect a gradual increase in mean elevation or partly closed hydrologic system behavior. Evidence of an active west-flowing fluvial system, providing a conduit for Late Eocene sediment and Oligocene ignimbrites, extending from what is now north-central Nevada to eastern California, supports a gradual increase in elevation from west to east as shown by the paleoaltimetry data. The region that is now northern Nevada was likely a gradually sloping high-elevation (~3-4 km) plateau in the Oligocene.

  4. Ocean and laboratory observations on waves over topography

    NASA Astrophysics Data System (ADS)

    Lam, F. P. A.

    2007-01-01

    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.

  5. Vegetation-precipitation controls on Central Andean topography

    NASA Astrophysics Data System (ADS)

    Jeffery, M. Louise; Yanites, Brian J.; Poulsen, Christopher J.; Ehlers, Todd A.

    2014-06-01

    Climatic controls on fluvial landscapes are commonly characterized in terms of mean annual precipitation. However, physical erosion processes are driven by extreme events and are therefore more directly related to the intensity, duration, and frequency of individual rainfall events. Climate also influences erosional processes indirectly by controlling vegetation. In this study, we explore how interdependent climate and vegetation properties affect landscape morphology at the scale of the Andean orogen. The mean intensity, duration, and frequency of precipitation events are derived from the TRMM 3B42v7 product. Relationships between mean hillslope gradients and precipitation event metrics, mean annual precipitation, vegetation, and bedrock lithology in the central Andes are examined by correlation analyses and multiple linear regression. Our results indicate that mean hillslope gradient correlates most strongly with percent vegetation cover (r = 0.56). Where vegetation cover is less than 95%, mean hillslope gradients increase with mean annual precipitation (r = 0.60) and vegetation cover (r = 0.69). Where vegetation cover is dense (>95%), mean hillslope gradients increase with increasing elevation (r = 0.74), decreasing inter-storm duration (r = -0.69), and decreasing precipitation intensity by ~0.5°/(mm d-1) (r = -0.56). Thus, we conclude that at the orogen scale, climate influences on topography are mediated by vegetation, which itself is dependent on mean annual precipitation (r = 0.77). Observations from the central Andes are consistent with landscape evolution models in which hillslope gradients are a balance between rock uplift, climatic erosional efficiency and erosional resistance of the landscape determined by bedrock lithology and vegetation.

  6. Erosion of Terrestrial Rift Flank Topography: A Quantitative Study

    NASA Technical Reports Server (NTRS)

    Weissel, Jeffrey K.

    1999-01-01

    Many rifted or passive continental margins feature a seaward-facing erosional escarpment which abruptly demarcates deeply weathered, low relief, interior uplands from a deeply incised, high relief coastal zone. It is generally accepted that these escarpments originate at the time of continental rifting and propagate inland through the elevated rift flank topography at rates on the order of 1 km/Myr over the course of a margin's history. Considering the length of passive margins worldwide and an average rift flank plateau height of several hundred meters, it is clear that sediment eroded from passive margins is an important component of the mass flux from continents to oceans through geologic time. The overall goal of the research reported here is to develop a quantitative understanding of the kinematics of escarpment propagation across passive margins and the underlying geological processes responsible for this behavior. Plateau-bounding escarpments in general exhibit two basic forms depending on the direction of surface water drainage on the plateau interior relative to the escarpment. Where surface water flows away from the escarpment, the escarpment takes the form of subdued embayments and promontories, such that its overall trend remains fairly straight as it evolves with time. Where upland streams flow across the escarpment, it takes the form of dramatic, narrow gorges whose heads appear to propagate up the plateau drainage systems as large-scale knickpoints. From work on the Colorado Plateau, Schmidt (1987) noted that the Colorado River is located much closer to the Grand Canyon's south rim, a drainage divide escarpment, than to the north rim, which is a gorge-like escarpment. The main implication is that the gorge-like form might be associated with higher long-term average erosion rates compared to the drainage divide escarpment type.

  7. Effects of topography and atmospheric structure on volcano infrasound

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

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

  8. Digital signal processing in AFM topography and recognition imaging

    NASA Astrophysics Data System (ADS)

    Adamsmair, Stefan; Ebner, Andreas; Hinterdorfer, Peter; Zagar, Bernhard

    2005-10-01

    Atomic force microscopy (AFM) has proven to be a powerful tool to observe topographical details at the nano- and subnanometer scale. Since this is a rather new technique, new enhancements with faster scanning rates, more accurate measurements and more detailed information were developed. This requires also a higher demand on the signal processing and the controlling software. Operating an AFM with analog driven hardware is often limited by drift and noise problems. Here we overcome this problem by introducing digital signal processing capable of accurately stabilizing the piezo control in the newly developed TREC (topography and recognition imaging) mode. In this mode topographical information and molecular recognition between tip bound ligand and surface bound receptors is simultaneously acquired. The sought information is conveyed by slight variations of the minima and maxima of the signal amplitudes. These variations are very small compared to the maximum possible DC deflection. Furthermore, the DC offset exhibits a rather large drift mostly attributed to temperature changes. To obtain reliable tracking results the oscillating photodiode signal needs to be nonlinearly filtered and efficiently separated into four major components: the maxima, the minima, the spatial average of the maxima, and the spatial average of the minima. The recognition image is then obtained by a nonlinear combination of these four components evaluated at spatial locations derived from the zero-crossings of the differentiated signal resulting from a modified differentiator FIR filter. Furthermore, to reliably estimate the DC drift an exponential tracking of the extrema by a first-order IIR filter is performed. The applicability of the proposed algorithms is demonstrated for biotin and avidin.

  9. Mapping the Topography of Mercury with MESSENGER Laser Altimetry

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

    The Mercury Laser Altimeter onboard MESSENGER involves unique design elements that deal with the challenges of being in orbit around Mercury. The Mercury Laser Altimeter (MLA) is one of seven instruments on NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft. MESSENGER was launched on 3 August 2004, and entered into orbit about Mercury on 18 March 2011 after a journey through the inner solar system. This involved six planetary flybys, including three of Mercury. MLA is designed to map the topography and landforms of Mercury's surface. It also measures the planet's forced libration (motion about the spin axis), which helps constrain the state of the core. The first science measurements from orbit taken with MLA were made on 29 March 2011 and continue to date. MLA had accumulated about 8.3 million laser ranging measurements to Mercury's surface, as of 31 July 2012, i.e., over six Mercury years (528 Earth days). Although MLA is the third planetary lidar built at the NASA Goddard Space Flight Center (GSFC), MLA must endure a much harsher thermal environment near Mercury than the previous instruments on Mars and Earth satellites. The design of MLA was derived in part from that of the Mars Orbiter Laser Altimeter on Mars Global Surveyor. However, MLA must range over greater distances and often in off-nadir directions from a highly eccentric orbit. In MLA we use a single-mode diode-pumped Nd:YAG (neodymium-doped yttrium aluminum garnet) laser that is highly collimated to maintain a small footprint on the planet. The receiver has both a narrow field of view and a narrow spectral bandwidth to minimize the amount of background light detected from the sunlit hemisphere of Mercury. We achieve the highest possible receiver sensitivity by employing the minimum receiver detection threshold.

  10. Hydroelastic response of a very large floating structure over a variable bottom topography

    Microsoft Academic Search

    Jo Hyun Kyoung; Sa Young Hong; Byoung Wan Kim; Seok Kyu Cho

    2005-01-01

    An influence of sea-bottom topography on the hydroelastic response of a Very Large Floating Structure (VLFS) is considered. When the floating structure is constructed near the shore, the sea-bottom topographical effect should be considered. In this study, the effect of sea-bottom topography is investigated for four different bottom cases. To calculate the sea-bottom effects rigorously, the finite-element method based on

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

    NASA Astrophysics Data System (ADS)

    Balmino, G.

    1993-06-01

    A spherical harmonic analysis is conducted for the topographies of the terrestrial planets using extant data sets to the highest possible degree and order, with a view to establishing the decay of such spectra over a larger range of frequencies and ascertain the limit of validity of the data sets employed. The shape of power spectra is confirmed for the cases of the earth and for Venus; Mars topography is still uncertain in many regions.

  12. Statistical characteristic and parameter characterization of 3D surface micro-topography on micro-EDM

    Microsoft Academic Search

    Haijuan Ding; Libin Guo; Hai Cui

    2009-01-01

    The characteristic of three-dimensional (3D) surface micro-topography of micro-EDM plays an important role on the component function properties. In this paper, two types of 3D surface micro-topography, which machined by micro-electrical discharge machining forming (micro-EDMF) and micro-wire electrical discharge machining (micro-WEDM), have been measured by the atomic force microscope (AFM) instrument after the surface data have been reshaped and denoised

  13. Efficient Time-Domain Image Formation with Precise Topography Accommodation for General Bistatic SAR Configurations

    Microsoft Academic Search

    Marc Rodriguez-Cassola; Pau Prats; Gerhard Krieger; Alberto Moreira

    2011-01-01

    Due to the lack of an appropriate symmetry in the acquisition geometry, general bistatic synthetic aperture radar (SAR) cannot benefit from the two main properties of low-to-moderate resolution monostatic SAR: azimuth-invariance and topography-insensitivity. The precise accommodation of azimuth-variance and topography is a real challenge for efficent image formation algorithms working in the Fourier domain, but can be quite naturally handled

  14. A Cyberinfrastructure Platform for Distribution of GeoEarthScope LiDAR Topography Data

    Microsoft Academic Search

    C. J. Crosby; V. Nandigam; J. R. Arrowsmith; S. Balakrishnan; N. Alex; C. Baru

    2008-01-01

    The recently completed GeoEarthScope airborne LiDAR (Light Detection And Ranging) topography acquisition will provide unprecedented data adjacent to active faults throughout the plate boundary region of western North America. Totaling more than 5000 square kilometers, these community-oriented data offer an high-resolution representation of fault zone topography and should be a revolutionary resource for researchers studying earthquake hazards, active faulting, landscape

  15. The Effect of Topography on Water Wetting and Micro\\/Nano Tribological Characteristics of Polymeric Surfaces

    Microsoft Academic Search

    Eui-Sung Yoon; Seung Ho Yang; Hosung Kong; Ki-Hwan Kim

    2003-01-01

    The effect of surface topography on the water-wetting nature and micro\\/nano tribological characteristics of polymer surfaces was experimentally studied. A plasma-treated thin polymer film and ion-beam-treated PTFE (polytetrafluoroethylene) were used as flat specimens. Thin polymer films were deposited on Si-wafer (100) by the parallel-plate plasma technique. The ion-beam-roughening treatment was performed to change the PTFE surface topography using a hollow

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

    NSDL National Science Digital Library

    Tau Alpha

    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.

  17. High Resolution Topography Analysis on Threading Edge Dislocations in 4H-SiC Epilayers

    SciTech Connect

    Kamata, I.; Nagano, M; Tsuchida, H; Chen, Y; Dudley, M

    2009-01-01

    Threading edge dislocations (TEDs) in a 4H-SiC epitaxial layer are investigated using high-resolution synchrotron topography. Six types of TED image are confirmed to correspond to the Burgers vector directions by a comparison of computer simulated images and observed topography images in crystal boundaries. Using a mapping method, a wide spatial distribution of the six types of TED is examined in a quarter section of a 2-inch wafer.

  18. Integrated approach to estimate the ocean's time variable dynamic topography including its covariance matrix

    NASA Astrophysics Data System (ADS)

    Becker, Silvia; Brockmann, Jan Martin; Schuh, Wolf-Dieter

    2014-05-01

    The ocean's mean dynamic topography as the difference between the sea surface and the geoid reflects many characteristics of the general ocean circulation. Consequently, it provides valuable information for evaluating or tuning ocean circulation models. However, the determination of the mean dynamic topography from satellite based gravity field and altimetric observations is not straightforward. For the integration of the dynamic topography into ocean circulation models not only the dynamic topography itself but also its inverse covariance matrix on the ocean model grid is required. We developed a rigorous combination method where both instrumental errors and omission errors are accounted for, including the determination of optimal relative weights between the observation groups. The altimetric mean sea surface is expressed as a sum of geoid heights represented in terms of spherical harmonics and the mean dynamic topography parameterized by a finite element method which can be directly related to the particular ocean model grid. The different observation groups are combined in terms of normal equations. This allows the direct determination of the normal equations of the mean dynamic topography which contain the appropriate weights for model-data misfits in least-squares ocean model inversions. The developed integrated approach can be extended by modeling the time variable component of the dynamic topography to provide estimates not only at a mean state but also at arbitrary points in time including a rigorously computed covariance matrix. The focus of this study is on the North Atlantic Ocean. We will present the conceptual design and dynamic topography estimates based on time variable data from several satellite altimeter missions in combination with GOCE and GRACE gravity field models.

  19. 7 The Numerical Wind Atlas for Ire-7.1 Topography for Ireland

    E-print Network

    7 The Numerical Wind Atlas for Ire- land 7.1 Topography for Ireland The topography of Ireland of British Island as it might influence the flow field in the northeast of Ireland. Table 4. Maximum terrain for the maps of Ireland used by KAMM. x 10 km 5 km 2.5 km Grid size 48 Ã? 54 90 Ã? 108 180 Ã? 212 points Max. h

  20. Push in South of the Hellas Basin Showing Topography from MOLA: New Color Map

    NSDL National Science Digital Library

    Tom Biddlecome

    1999-11-22

    Zoom into the region of Mars just south of the Hellas Basin showing topography data from MOLA. This animation uses a color table designed to highlight the topography at the south pole. White colors indicate elevations in excess of 3012 meters, red shows elevations between 2500 and 3012 meters, yellow shows elevations from 2450 to 2500 meters, dark cyan shows elevations from 2150 to 2450 meters, dark violet shows elevations from 320 to 2150 meters.

  1. The influence of eroding topography on steady-state isotherms. Application to fission track analysis

    Microsoft Academic Search

    Kurt Stuewe; Lee White; Rod Brown

    1994-01-01

    The influence of surface topography on the form of steady-state isotherms during erosion-driven denudation is investigated. This is of particular interest to the interpretation of low-temperature geochronological data, for example fission track data, because this rests generally on the untested assumption that isotherms are not perturbed by topography and, therefore, that the data can be interpreted with one-dimensional models. In

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

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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 %.

  4. The differential regulation of osteoblast and osteoclast activity by surface topography of hydroxyapatite coatings.

    PubMed

    Costa, Daniel O; Prowse, Paul D H; Chrones, Tom; Sims, Stephen M; Hamilton, Douglas W; Rizkalla, Amin S; Dixon, S Jeffrey

    2013-10-01

    The behavior of bone cells is influenced by the surface chemistry and topography of implants and scaffolds. Our purpose was to investigate how the topography of biomimetic hydroxyapatite (HA) coatings influences the attachment and differentiation of osteoblasts, and the resorptive activity of osteoclasts. Using strategies reported previously, we directly controlled the surface topography of HA coatings on polycaprolactone discs. Osteoblasts and osteoclasts were incubated on HA coatings having distinct isotropic topographies with submicrometer and micro-scale features. Osteoblast attachment and differentiation were greater on more complex, micro-rough HA surfaces (Ra ~2 ?m) than on smoother topographies (Ra ~1 ?m). In contrast, activity of the osteoclast marker tartrate-resistant acid phosphatase was greater on smoother than on micro-rough surfaces. Furthermore, scanning electron microscopy revealed the presence of resorption lacunae exclusively on smoother HA coatings. Inhibition of resorption on micro-rough surfaces was associated with disruption of filamentous actin sealing zones. In conclusion, HA coatings can be prepared with distinct topographies, which differentially regulate responses of osteoblasts, as well as osteoclastic activity and hence susceptibility to resorption. Thus, it may be possible to design HA coatings that induce optimal rates of bone formation and degradation specifically tailored for different applications in orthopedics and dentistry. PMID:23830579

  5. Simultaneous inversion for mantle shear velocity and the topography of transition zone discontinuities

    NASA Astrophysics Data System (ADS)

    Gu, Y. J.; Dziewonski, A. M.

    2001-05-01

    A method is presented for the simultaneous inversions of shear velocity in the mantle and the topography of transition zone discontinuities. Each travel time residual, corrected for crust and free surface topography, is modeled as resulting from contributions from three-dimensional shear velocity perturbations to a spherical Earth model and boundary undulations to the 410 and 660 km discontinuities. This approach minimizes tradeoffs between velocity and topography. We expand the lateral variations in velocity and the topography of each discontinuity using 362 spherical B-splines; we expand the radial variations using 14 cubic B-splines. To increase the reliability of the measurements, particularly in the undersampled southern hemisphere, we re-examine the topography of the 410- and 660 km discontinuities from more than 21,000 SH-component records. This new data set is significantly larger than those used earlier studies of SS precursors. The long-wavelength features of our new topography maps of the 410- and 660-km discontinuities are compatible with results of earlier studies: the large-scale patterns are dominated by low degree spherical harmonics, particularly at degrees 1 and 2. We also include an independent measurement of the global transition zone thickness for additional constraints on the structure in the transition zone. The best-fit model from the joint inversion reduces the variance of the absolute and differential travel times of S, SS and ScS by 40 to 70 %, and the differential travel times of SS precursors by up to 90%.

  6. GMRT observations of the Ophiuchus galaxy cluster

    NASA Astrophysics Data System (ADS)

    Murgia, M.; Eckert, D.; Govoni, F.; Ferrari, C.; Pandey-Pommier, M.; Nevalainen, J.; Paltani, S.

    2010-05-01

    Aims: Observations with the Very Large Array telescope at 1477 MHz revealed the presence of a radio mini-halo surrounding the faint central point-like radio source in the Ophiuchus cluster of galaxies. In this work we present a study of the radio emission from this cluster of galaxies at lower radio frequencies. Methods: We observed the Ophiuchus cluster at 153, 240, and 614 MHz with the Giant Metrewave Radio Telescope. Results: The mini-halo is clearly detected at 153 and 240 MHz, the frequencies at which we reached the best sensitivity to the low-surface brightness diffuse emission, while it is not detected at 610 MHz because of the too low signal-to-noise ratio at this frequency. The most prominent feature at low frequencies is a patch of diffuse steep spectrum emission located at about 5´ south-east from the cluster centre. By combining these images with that at 1477 MHz, we derived the spectral index of the mini-halo. Globally, the mini-halo has a low-frequency spectral index of ?240153 ? 1.4±0.3 and an high-frequency spectral index of ?1477240 ? 1.60±0.05. Moreover, we measure a systematic increase of the high-frequency spectral index with radius: the azimuthal radial average of ?1477240 increases from about 1.3, at the cluster centre, up to about 2.0 in the mini-halo outskirts. Conclusions: The observed radio spectral index agrees with that obtained by modelling the non-thermal hard X-ray emission in this cluster of galaxies. We assume that the X-ray component arises from inverse-Compton scattering between the photons of the cosmic microwave background and a population of non-thermal electrons, which are isotropically distributed and whose energy spectrum is a power law with an index p. We derive that the electrons energy spectrum should extend from a minimum Lorentz factor of ?_min ? 700 up to a maximum Lorentz factor of ?_max ? 3.8 × 104 with an index p = 3.8±0.4. The volume-averaged strength for a completely disordered intra-cluster magnetic field is BV ? 0.3±0.1 ?G.

  7. The GMRT: System Parameters and Current Status

    E-print Network

    Udgaonkar, Jayant B.

    on the feed turret) where the user can select which feed frequency signals appear at the ou. The feeds presently available are the 151, 325, 610/235 and the 1000-1450 MHz feeds. The reflecting surface to the highest frequency. Both the orthogonal polarisations are brought to the control room from each antenna

  8. Large Eddy Simulation over a 3D topography:Large Eddy Simulation over a 3D topography: Comparison with the results of the field campaign

    E-print Network

    be used to determine is a site is suitable for the deployment of wind turbines. The simulations are tested models ranging from numerical codes to wind tunnel experiments. Stations location on the Bolund Island wind fields aroundImmersed Boudndary Method to model wind fields around topographies. That could

  9. The Katla Subglacial Volcano: Topography and Flow Paths of Joekulhlaups

    NASA Astrophysics Data System (ADS)

    Björnsson, H.; Pálsson, F.; Gudmundsson, M. T.

    2000-08-01

    The bedrock topography of the MyrdalsjoEkull ice cap has been mapped with radio echo-soundings. The ice cap is located at the southern tip of the eastern volcanic zone in Iceland, which is propagating southwards. The ice cap is underlain by a huge caldera that has erupted 20 times during the last 1100 years. The rims of the caldera encircle an area of 110 sq km. The caldera is 600 to 750 m deep; the lowest elevation of the floor is 650 m. a. s. 1. and the highest rims rise to 1400 m. Three outlet glaciers have eroded 300 to 500 m deep breaches in the crater rim. The difference in morphology between the northern and southern caldera floor may reflect the level of subglacial volcanic activity. The northern floor is deeper and more level (an area of 25 sq km below 800 m) whereas the southern floor is more rugged and elevated (subglacial ridges and mounts rise above 1100 m surrounded by depressions down to 750 m). A row of craters, trending north-northwest, is seen 2 km within the eastern rim of the caldera. The last eruption site (of 1918 A.D.) is situated at the eastern part of the caldera, beneath 400 m thick ice. A number of ridges radiate out from the caldera, however, none towards south. One ridge strikes west towards the neighboring volcano Eyjafjallajoekull and a second ridge strikes east from the eastern rim of the caldera. Ridges also radiate towards northwest, north, and northeast from the caldera. A linear depression, bounded by steep slopes, 150 m deep and 1.5 km wide, strikes NE towards the volcanic fissure Eldgja which produced a lava flow of 14 cubic km in 930 A.D. Presently, geothermal activity is displayed by twelve small depressions in the glacier surface (of diameter up to 1 km). Melt water is accumulated beneath two or three of these cauldrons and frequently drained in small outburst floods (joekulhlaups). From an area of 70 sq km within the caldera, melt water is drained down to Myrdalssandur, as did 18 of 20 recorded joekulhlaups in historical times; from 20 sq km down to Solheimasandur as two of the joekulhlaups; the third route was taken by a joekulhaup in 1600 B.P.

  10. Tracing tectonics in topography in the Bükk Mountains, NE Hungary

    NASA Astrophysics Data System (ADS)

    McIntosh, Richard William; Bódi, Erika; Kozák, Miklós; Buday, Tamás

    2013-04-01

    Relief, as we see it today, is shaped and formed by numerous processes the dominance of which is determined by the geographical location of the area the relief belongs to. In areas, however, where solid rocks of distinct tectonic history with clearly definable deformation elements are close to the surface the structural geological character of the subsurface formations fundamentally determine the topography. Location of the most spectacular peaks, shape of the ridges between them, location and orientation of valleys and even the direction of smaller valley sections are determined by the structural features and conditions of the underlying geology. The authors carried out structural geological analyses in an area (Bükk Mountains, NE Hungary) showing a relatively diverse geology composed of Triassic carbonates, Triassic and Jurassic siliciclastic sediments (foliated sandstone, shales) and Triassic igneous rocks (metamorphosed basalt, andesite and rhyolite). Structural elements of both brittle and ductile deformations have been identified and measured in the form of frontal thrusts, transverse (tension) joints, conjugated lithoclases, cleavage planes, fold limbs and fold axes. Based on the results, the orientation of two major stress fields acting in several phases (mostly in the Cretaceous) have been identified as responsible for the production of the major structural elements. Observing the interesting orientation of valleys, the strange form of ridges and the appearance of peculiar landforms both in field and on topographic maps / satellite images made the authors curious to find their explanation. As a result, the orientation of valleys was correlated to the orientation of the prevailing brittle structural elements in a model area within the Bükk Mountains. Even the smaller valley sections were correlated to the joint directions in the model area. Direction of the lines of the ridges was also correlated to the structural features of the model area. Strong correlation between the morphological and structural features was detected even in underground morphological forms as the direction of the passages of caves in the model area also matched the direction of brittle structural elements. Furthermore, the appearance of unusual relief forms could be explained by the occurrence of special structural features produced by the specific interaction of the two dominant stress fields and the resultant superposed structural elements. The results enable us to extend the structural analysis and re-construction established for a model area over the surrounding areas without further detailed structural analyses in case a generally similar geological setting and tectonic history can be assumed.

  11. Gravity, Topography, and Magnetic Field of Mercury from Messenger

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

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

    PubMed

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

    2013-10-01

    Fire is a dominant process in boreal forest landscapes and creates a spatial patch mosaic with different burn severities and age classes. Quantifying effects of vegetation and topography on burn severity provides a scientific basis on which forest fire management plans are developed to reduce catastrophic fires. However, the relative contribution of vegetation and topography to burn severity is highly debated especially under extreme weather conditions. In this study, we hypothesized that relationships of vegetation and topography to burn severity vary with fire size. We examined this hypothesis in a boreal forest landscape of northeastern China by computing the burn severity of 24 fire patches as the difference between the pre- and post-fire Normalized Difference Vegetation Index obtained from two Landsat TM images. The vegetation and topography to burn severity relationships were evaluated at three fire-size levels of small (<100 ha, n = 12), moderate (100-1,000 ha, n = 9), and large (>1,000 ha, n = 3). Our results showed that vegetation and topography to burn severity relationships were fire-size-dependent. The burn severity of small fires was primary controlled by vegetation conditions (e.g., understory cover), and the burn severity of large fires was strongly influenced by topographic conditions (e.g., elevation). For moderate fires, the relationships were complex and indistinguishable. Our results also indicated that the pattern trends of relative importance for both vegetation and topography factors were not dependent on fire size. Our study can help managers to design fire management plans according to vegetation characteristics that are found important in controlling burn severity and prioritize management locations based on the relative importance of vegetation and topography. PMID:23887487

  13. Estimating Vegetation Height and Bare-Earth Topography from SRTM Data using Fourier Spectral Decomposition

    NASA Astrophysics Data System (ADS)

    Gangodagamage, C.; Liu, D.; Alsdorf, D.

    2010-12-01

    In this study, LiDAR vegetation topography (bare-earth + vegetation height), LiDAR bare-earth topography, the National Elevation Data (NED) set, and Shuttle Radar Terrain Mission (SRTM) measurements are used to develop a statistical model to explore the possibility of extracting vegetation height measurements and accurate high resolution bare-earth topography from SRTM data. The key innovation is to obtain the statistical signature of the vegetation height measurements in the Fourier domain by taking advantage of the well-known linearity in additive properties of the Fourier transform. We demonstrate that the power-law relationship, P(k) ? k^(-?), as shown by the bare-earth topography, breaks down approximately at a cross-over wavenumber, k=k_c, due to the vegetation height effect using four different topographic and vegetation study locations in the United States. We document that the vegetation effect mainly dominates the high-frequency contents of the vegetation topography from 2-180 m, 1-60 m, and 1-70 m for the South Fork Eel River, California; Flathead Lake, Montana; and Tenderfoot Creek, Montana, LiDAR data, respectively, and from 1-240 m for 30 m SRTM data for the Jesup, Georgia site. Finally, we demonstrate our ability to obtain a high resolution bare-earth topography with RMSE of 9.6 m, 2.2 m, and 2.9 m and vegetation height with RMSE of 11.0 m (11% error), 4.5 m (12% error), and 1.6 m (8% error) for LiDAR data study sites, whereas for the SRTM data, bare-earth topography and vegetation height are obtained with RMSE values of 5.4 m and 3.1 m, respectively, for the Jesup site. Model Vegetation height

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

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

    PubMed

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

    2015-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Burov, E. B.; Gerya, T.

    2013-12-01

    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.

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

    NASA Technical Reports Server (NTRS)

    Bryan, J.; Rabine, David L.

    1998-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-07-01

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

  19. Biodiversity of Jinggangshan Mountain: The Importance of Topography and Geographical Location in Supporting Higher Biodiversity

    PubMed Central

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

    2015-01-01

    Diversity is mainly determined by climate and environment. In addition, topography is a complex factor, and the relationship between topography and biodiversity is still poorly understood. To understand the role of topography, i.e., altitude and slope, in biodiversity, we selected Jinggangshan Mountain (JGM), an area with unique topography, as the study area. We surveyed plant and animal species richness of JGM and compared the biodiversity and the main geographic characteristics of JGM with the adjacent 4 mountains. Gleason’s richness index was calculated to assess the diversity of species. In total, 2958 spermatophyte species, 418 bryophyte species, 355 pteridophyte species and 493 species of vertebrate animals were recorded in this survey. In general, the JGM biodiversity was higher than that of the adjacent mountains. Regarding topographic characteristics, 77% of JGM’s area was in the mid-altitude region and approximately 40% of JGM’s area was in the 10°–20° slope range, which may support more vegetation types in JGM area and make it a biodiversity hotspot. It should be noted that although the impact of topography on biodiversity was substantial, climate is still a more general factor driving the formation and maintenance of higher biodiversity. Topographic conditions can create microclimates, and both climatic and topographic conditions contribute to the formation of high biodiversity in JGM. PMID:25763820

  20. Model based OPC for implant layer patterning considering wafer topography proximity (W3D) effects

    NASA Astrophysics Data System (ADS)

    Park, Songyi; Youn, Hyungjoo; Chung, Noyoung; Maeng, Jaeyeol; Lee, Sukjoo; Ku, Jahum; Xie, Xiaobo; Lan, Song; Feng, Mu; Vellanki, Venu; Kim, Joobyoung; Baron, Stanislas; Liu, Hua-Yu; Hunsche, Stefan; Woo, Soung-Su; Park, Seung-Hoon; Yoon, Jong-Tai

    2012-03-01

    Implant layer patterning is becoming challenging with node shrink due to decreasing critical dimension (CD) and usage of non-uniform reflective substrates without bottom anti-reflection coating (BARC). Conventional OPC models are calibrated on a uniform silicon substrate and the model does not consider any wafer topography proximity effects from sub-layers. So the existing planar OPC model cannot predict the sub-layer effects such as reflection and scattering of light from substrate and non-uniform interfaces. This is insufficient for layers without BARC, e.g., implant layer, as technology node shrinks. For 45-nm and larger nodes, the wafer topography proximity effects in implant layer have been ignored or compensated using rule based OPC. When the node reached 40 nm and below, the sub-layer effects cause undesired CD variation and resist profile change. Hence, it is necessary to model the wafer topography proximity effects accurately and compensate them by model based OPC. Rigorous models can calculate the wafer topography proximity effects quite accurately if well calibrated. However, the run time for model calibration and OPC compensation are long by rigorous models and they are not suitable for full chip applications. In this paper, we demonstrate an accurate and rapid method that considers wafer topography proximity effects using a kernel based model. We also demonstrate application of this model for full chip OPC on implant layers.

  1. Geophysical investigations of the East Greenland Caledonides using receiver functions, gravity and topography data

    NASA Astrophysics Data System (ADS)

    Schiffer, C.; Jacobsen, B. H.; Balling, N.; Nielsen, S. B.

    2012-04-01

    The present-day topography and crustal structure of the East Greenland Caledonides are a product of various events, including the Caledonian orogeny, lithospheric extensional collapse, continental breakup and erosional processes. The topographic elevation appears high in this region, still after considering erosional uplift, connected to fjord formation. This apparent longevity of topography remains a matter of discussion. In this context the relationship of topography to crustal thickness and isostasy is a central aspect. Erosion and possible subcrustal processes are of further importance. Shallow crustal structures related to extensional basin formation, a lower crustal high velocity layer and a crustal root have to be considered. A profile of 11 temporary broadband stations was deployed and maintained by Aarhus University for a period of 2 years (2009 - 2011). The approximately 270 km long Ella Ø array crosses the East Greenland Caledonides from the ice sheet to the coastline at about 73° north. The data are of high quality. Initial Receiver Function results are interpreted together with corresponding gravity and topography data and additionally compared with synthetic data, using velocity models from published wide-angle seismic studies in the area. The evolution of the East Greenland and Norwegian Caledonides at the conjugated margins may be closely connected. A comparison with a similar study in Norway will give insight to what extend topography, crustal and upper mantle structures on both sides correlate and display similarities as well as a common evolution and tectonic origin.

  2. On the residual isostatic topography effect in the gravimetric Moho determination

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

    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.

  3. Cooperative control of blood compatibility and re-endothelialization by immobilized heparin and substrate topography.

    PubMed

    Ding, Yonghui; Yang, Meng; Yang, Zhilu; Luo, Rifang; Lu, Xiong; Huang, Nan; Huang, Pingbo; Leng, Yang

    2015-03-01

    A wide variety of environmental cues provided by the extracellular matrix, including biophysical and biochemical cues, are responsible for vascular cell behavior and function. In particular, substrate topography and surface chemistry have been shown to regulate blood and vascular compatibility individually. The combined impact of chemical and topographic cues on blood and vascular compatibility, and the interplay between these two types of cues, are subjects that are currently being explored. In the present study, a facile polydopamine-mediated approach is introduced for immobilization of heparin on topographically patterned substrates, and the combined effects of these cues on blood compatibility and re-endothelialization are systematically investigated. The results show that immobilized heparin and substrate topography cooperatively modulate anti-coagulation activity, endothelial cell (EC) attachment, proliferation, focal adhesion formation and endothelial marker expression. Meanwhile, the substrate topography is the primary determinant of cell alignment and elongation, driving in vivo-like endothelial organization. Importantly, combining immobilized heparin with substrate topography empowers substantially greater competitive ability of ECs over smooth muscle cells than each cue individually. Moreover, a model is proposed to elucidate the cooperative interplay between immobilized heparin and substrate topography in regulating cell behavior. PMID:25541345

  4. Incorporating topography into crustal-scale wave-equation imaging through conformal mapping

    NASA Astrophysics Data System (ADS)

    Shragge, J.; Sava, P.

    2004-12-01

    Migration of seismic land data acquired over topography presents significant challenges for seismic imaging technology. One technique commonly used to alleviate the deleterious effects of topography is to include a wavefield datuming step in the pre-migration processing flow. Locations exhibiting strong, near-surface lateral velocity contrast accompanying topography, though, may have significant wavefield triplication that leads to non-optimal datuming procedures; especially if Kirchhoff-based methods are used. Accordingly, the use of novel wave-equation approaches that naturally handle wavefield-multipathing should lead in these situations to significantly improved datuming or migration procedures. Conformal mapping is a technique used widely in applied physics and engineering fields to facilitate numerical solution of boundary value problems involving surfaces exhibiting complex geometry. The general reason for applying this procedure is to transform solution domains marked by complicated boundaries, such as topography, to domains that are more regular, such as Cartesian. The conformal mapping transforms may then be used to define wavefield-extrapolation equations appropriate for using in the new domain. In this paper, we demonstrate that the conformal mapping transform coupled with the Riemannian wavefield extrapolation (Sava, 2004) generate orthogonal meshes, herein termed topographic-coordinate systems, and governing equations appropriate for incorporating topography directly into wave-equation migration. This premise is illustrated with poststack and prestack crustal-scale sized synthetic data sets with a topographic surface taken from the Foothills region of British Columbia, Canada.

  5. Nanoscale topography and chemistry affect embryonic stem cell self-renewal and early differentiation.

    PubMed

    Lapointe, Vanessa L S; Fernandes, Ana Tiago; Bell, Nia C; Stellacci, Francesco; Stevens, Molly M

    2013-12-01

    Adherent cells respond to a wide range of substrate cues, including chemistry, topography, hydrophobicity, and surface energy. The cell-substrate interface is therefore an important design parameter in regenerative medicine and tissue engineering applications, where substrate cues are used to influence cell behavior. Thin films comprising 4.5 nm (average diameter) gold nanoparticles coated with a mixture of two alkanethiols can confer hemispherical topography and specific chemistry to bulk substrates. The behavior of murine embryonic stem cells (ESCs) on the thin films can then be compared with their behavior on self-assembled monolayers of the same alkanethiols on vapor-deposited gold, which lack the topographical features. Cells cultured both with and without differentiation inhibitors are characterized by immunofluorescence for Oct4 and qPCR for Fgf5, Foxa2, Nanog, Pou5f1, and Sox2. Nanoscale chemistry and topography are found to influence stem cell differentiation, particularly the early differentiation markers, Fgf5 and Foxa2. Nanoscale topography also affects Oct4 localization, whereas the chemical composition of the substrate does not have an effect. It is demonstrated for the first time that ESCs can sense topographical features established by 4.5 nm particles, and these findings suggest that nanoscale chemistry and topography can act synergistically to influence stem cell differentiation. This study furthers the understanding of the effects of these substrate properties, improving our ability to design materials to control stem cell fate. PMID:23852884

  6. Quantitative characterization of the surface topography of rolled sheets by laser scanning microscopy and fourier transformation

    NASA Astrophysics Data System (ADS)

    Gjønnes, Liv

    1996-08-01

    The surface of twin-roll cast aluminum sheets undergoes dramatic changes during cold rolling. This is mainly due to variables in the roll gap, topography of the rolls, lubrication, material properties, and in particular the initial structure and topography of the cast sheet. Therefore, it is important to have means to quantitatively describe the changes in the surface structure of each pass and from pass to pass in order to optimize the desired final surface structure. To achieve this, the laser scanning microscope (LSM) with its confocal technique has been employed to image the three-dimensional (3-D) topography and to digitize the image for further computer analysis. The digitization of the image is primarily motivated by the need to introduce a Fourier transformation of the surface topography. The method is effective in describing qualitative periodic trends in the surface features. Information is gained on the shape and periodicities as well as roughness directionality. For instance, grooves and cross hatches and their remnants can be followed from one pass to the other. Important characteristics of the surface topography such as rolling ridges and shingles can also easily be characterized.

  7. SWOT, The Surface Water and Ocean Topography Satellite Mission (Invited)

    NASA Astrophysics Data System (ADS)

    Alsdorf, D.; Andreadis, K.; Bates, P. D.; Biancamaria, S.; Clark, E.; Durand, M. T.; Fu, L.; Lee, H.; Lettenmaier, D. P.; Mognard, N. M.; Moller, D.; Morrow, R. A.; Rodriguez, E.; Shum, C.

    2009-12-01

    Surface fresh water is essential for life, yet we have surprisingly poor knowledge of its variability in space and time. Similarly, ocean circulation fundamentally drives global climate variability, yet the ocean current and eddy field that affects ocean circulation and heat transport at the sub-mesoscale resolution and particularly near coastal and estuary regions, is poorly known. About 50% of the vertical exchange of water properties (nutrients, dissovled CO2, heat, etc) in the upper ocean is taking place at the sub-mesoscale. Measurements from the Surface Water and Ocean Topography satellite mission (SWOT) will make strides in understanding these processes and improving global ocean models for studying climate change. SWOT is a swath-based interferometric-altimeter designed to acquire elevations of ocean and terrestrial water surfaces at unprecedented spatial and temporal resolutions. The mission will provide measurements of storage changes in lakes, reservoirs, and wetlands as well as estimates of discharge in rivers. These measurements are important for global water and energy budgets, constraining hydrodynamic models of floods, carbon evasion through wetlands, and water management, especially in developing nations. Perhaps most importantly, SWOT measurements will provide a fundamental understanding of the spatial and temporal variations in global surface waters, which for many countries are the primary source of water. An on-going effort, the “virtual mission” (VM) is designed to help constrain the required height and slope accuracies, the spatial sampling (both pixels and orbital coverage), and the trade-offs in various temporal revisits. Example results include the following: (1) Ensemble Kalman filtering of VM simulations recover water depth and discharge, reducing the discharge RMSE from 23.2% to 10.0% over an 84-day simulation period, relative to a simulation without assimilation. (2) Ensemble-based data assimilation of SWOT like measurements yields bathymetric slope and depth to within 3.0 microradians and 50 cm, respectively. (3) SWOT measurements of storage changes in lakes larger than 1 km2 will have relative errors generally less than 5% whereas errors for one-hectare size lakes will be about 20%. (4) SWOT estimates of discharge compared to a one-year model-based “truth” data set suggest that instantaneous discharge estimates will have a median relative RMSE of 10.9% and that 86% of all instantaneous errors will be less than 25%. (5) Based on a global distribution of gauge-based discharge and candidate SWOT orbits with varying spatial and temporal sampling, SWOT errors in instantaneous discharge will be less than 25% for rivers wider than 50 m, whereas errors in monthly discharge will be less than 20% for rivers with drainage areas larger than 7000 km2. (6) We estimate that currently available satellite nadir altimetry data cannot monitor more than 15% of the global lake volume variation, whereas from 50% to more than 65% of the global lake volume variation will be observed by SWOT.

  8. Estimating Effective Elastic Thickness on Venus from Gravity and Topography: Robust Results from Multi-taper and Maximum-Likelihood Analysis

    NASA Astrophysics Data System (ADS)

    Eggers, G. L.; Lewis, K. W.; Simons, F. J.

    2012-12-01

    Venus has undergone a markedly different evolution than Earth. Its tectonics do not resemble the plate-tectonic system observed on Earth, and many surface features—such as tesserae and coronae—lack terrestrial equivalents. To understand Venus' tectonics is to understand its lithosphere. Lithospheric parameters such as the effective elastic thickness have previously been estimated from the correlation between topography and gravity anomalies, either in the space domain or the spectral domain (where admittance or coherence functions are estimated). Correlation and spectral analyses that have been obtained on Venus have been limited by geometry (typically, only rectangular or circular data windows were used), and most have lacked robust error estimates. There are two levels of error: the first being how well the correlation, admittance or coherence can be estimated; the second and most important, how well the lithospheric elastic thickness can be estimated from those. The first type of error is well understood, via classical analyses of resolution, bias and variance in multivariate spectral analysis. Understanding this error leads to constructive approaches of performing the spectral analysis, via multi-taper methods (which reduce variance) with well-chosen optimal tapers (to reduce bias). The second type of error requires a complete analysis of the coupled system of differential equations that describes how certain inputs (the unobservable initial loading by topography at various interfaces) are being mapped to the output (final, measurable topography and gravity anomalies). The equations of flexure have one unknown: the flexural rigidity or effective elastic thickness—the parameter of interest. Fortunately, we have recently come to a full understanding of this second type of error, and derived a maximum-likelihood estimation (MLE) method that results in unbiased and minimum-variance estimates of the flexural rigidity under a variety of initial-loading scenarios. As part of our MLE procedure we assume that the initial topographic loading follows a process with Matern covariance, which is being independently tested. We have sought to revise earlier estimates of Venusian lithospheric thickness by using locally optimizing Cartesian "Slepian" windows. Those tapers optimally bound an arbitrarily-shaped geologic feature given the available bandwidth, reducing the influence of noise and signal generated outside the area of interest. To generate these windows, we created a map of Venus, dividing the planet into geologically coherent regions bounded by closed curves. Previous regional maps of Venus either lacked specificity in their described regions or were too detailed for regional-scale studies. With this map, a synthesis of previous efforts and original mapping, the relation of topography and gravity anomaly for local features can be studied using both Slepian multi-tapering of admittance, and by MLE methods. The data sets used were spherical-harmonic models of topography and gravity anomalies based on measurements by the Magellan spacecraft. They remain the highest-resolution data sets, though with our new analysis methods, we look forward to any future missions that will return topography and gravity data with better accuracy over smaller footprints, such as are now available for Earth, Moon, and Mars.

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

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    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.

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

    PubMed Central

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

    2013-01-01

    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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Giusca, Claudiu L.; Leach, Richard K.

    2013-10-01

    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.

  13. A framework for integration of scientific applications into the OpenTopography workflow

    NASA Astrophysics Data System (ADS)

    Nandigam, V.; Crosby, C.; Baru, C.

    2012-12-01

    The NSF-funded OpenTopography facility provides online access to Earth science-oriented high-resolution LIDAR topography data, online processing tools, and derivative products. The underlying cyberinfrastructure employs a multi-tier service oriented architecture that is comprised of an infrastructure tier, a processing services tier, and an application tier. The infrastructure tier consists of storage, compute resources as well as supporting databases. The services tier consists of the set of processing routines each deployed as a Web service. The applications tier provides client interfaces to the system. (e.g. Portal). We propose a "pluggable" infrastructure design that will allow new scientific algorithms and processing routines developed and maintained by the community to be integrated into the OpenTopography system so that the wider earth science community can benefit from its availability. All core components in OpenTopography are available as Web services using a customized open-source Opal toolkit. The Opal toolkit provides mechanisms to manage and track job submissions, with the help of a back-end database. It allows monitoring of job and system status by providing charting tools. All core components in OpenTopography have been developed, maintained and wrapped as Web services using Opal by OpenTopography developers. However, as the scientific community develops new processing and analysis approaches this integration approach is not scalable efficiently. Most of the new scientific applications will have their own active development teams performing regular updates, maintenance and other improvements. It would be optimal to have the application co-located where its developers can continue to actively work on it while still making it accessible within the OpenTopography workflow for processing capabilities. We will utilize a software framework for remote integration of these scientific applications into the OpenTopography system. This will be accomplished by virtually extending the OpenTopography service over the various infrastructures running these scientific applications and processing routines. This involves packaging and distributing a customized instance of the Opal toolkit that will wrap the software application as an OPAL-based web service and integrate it into the OpenTopography framework. We plan to make this as automated as possible. A structured specification of service inputs and outputs along with metadata annotations encoded in XML can be utilized to automate the generation of user interfaces, with appropriate tools tips and user help features, and generation of other internal software. The OpenTopography Opal toolkit will also include the customizations that will enable security authentication, authorization and the ability to write application usage and job statistics back to the OpenTopography databases. This usage information could then be reported to the original service providers and used for auditing and performance improvements. This pluggable framework will enable the application developers to continue to work on enhancing their application while making the latest iteration available in a timely manner to the earth sciences community. This will also help us establish an overall framework that other scientific application providers will also be able to use going forward.

  14. In situ measurement of MEMS topography based on phase-shifting interferometry

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Rong, Hua

    2015-02-01

    Currently, phase-shifting interferometry is widely used in MEMS (micro-electro-mechanical system) microsurface topography measurements, and an expensive and high-precision piezoelectric transducer (PZT) is often necessary to realize phase-shift operation. Because of the feature of a MEMS structure which always has a flat substrate, a practical algorithm to calculate phase shifts by fast Fourier transformation (FFT) from gathered interference fringes of the substrate is presented, then microsurface topography can be reconstructed according to the obtained phase shifts. By means of the presented algorithm, an expensive and high-precision PZT is unnecessary and the phase-shift operation can even be carried out by rotating the fine focus adjustment knob. The accuracy and feasibility of the method have been verified by experiments. Experiments indicated that the presented method can satisfy the needs of in situ MEMS topography measurements and is very simple.

  15. Structural Characterization of Doped GaSb Single Crystals by X-ray Topography

    SciTech Connect

    Honnicke, M.G.; Mazzaro, I.; Manica, J.; Benine, E.; M da Costa, E.; Dedavid, B. A.; Cusatis, C.; Huang, X. R.

    2009-09-13

    We characterized GaSb single crystals containing different dopants (Al, Cd and Te), grown by the Czochralski method, by x-ray topography and high angular resolution x-ray diffraction. Lang topography revealed dislocations parallel and perpendicular to the crystal's surface. Double-crystal GaSb 333 x-ray topography shows dislocations and vertical stripes than can be associated with circular growth bands. We compared our high-angular resolution x-ray diffraction measurements (rocking curves) with the findings predicted by the dynamical theory of x-ray diffraction. These measurements show that our GaSb single crystals have a relative variation in the lattice parameter ({Delta}d/d) on the order of 10{sup -5}. This means that they can be used as electronic devices (detectors, for example) and as x-ray monochromators.

  16. Dependence of image grey values on topography in SIR-B images

    NASA Technical Reports Server (NTRS)

    Domik, G.; Leberl, F.; Cimino, J.

    1988-01-01

    This paper focuses on the use of a high resolution digital elevation model (DEM) to aid in rectifying and enhancing synthetic aperture radar images. Using a synthetic backscatter image, the SIR-B images are manually rectified and resampled to remove geometric distortions caused by topography. In a second step, an improved reflectance function of incidence angle is derived from the DEM and the rectified image and this function is used to reduce radiometric effects of topography yielding an albedo image which clearly shows the thematic, as opposed to topographic content of the image. The procedure is tested on four SIR-B images of a scene in Argentina (crossover point) that is imaged under different azimuth and incidence angles. The similarity of the resulting images indicates that the procedure effectively reduces artefacts from the images that are dependent on topography.

  17. An analytic solution for barotropic flow along a variable slope topography

    NASA Astrophysics Data System (ADS)

    Kuehl, Joseph J.

    2014-11-01

    An analytic solution is derived for the generic oceanographic situation of a barotropic current flowing along sloping topography. It is shown that the shallow water equations can be reduced to a heat-like equation in which ?effect is balanced by Ekman dissipation. For constant topography, the system is found to admit a well-known similarity solution and this solution is generalized to the case of variable topography. Several properties of the solution are explored, and an example is given for flow along the northern Gulf of Mexico slope, between the De Soto Canyon and the Mississippi Canyon. This "Topographic ?-plume" solution may serve as a model for further research concerning the influence exerted by geophysical boundary layers on the interior flow via their structure and stability.

  18. Improving the geoid: Combining altimetry and mean dynamic topography in the California coastal ocean

    NASA Astrophysics Data System (ADS)

    Mazloff, Matthew R.; Gille, Sarah T.; Cornuelle, Bruce

    2014-12-01

    Satellite gravity mapping missions, altimeters, and other platforms have allowed the Earth's geoid to be mapped over the ocean to a horizontal resolution of approximately 100 km with an uncertainty of less than 10 cm. At finer resolution this uncertainty increases to greater than 10 cm. Achieving greater accuracy requires accurate estimates of the dynamic ocean topography (DOT). In this study two DOT estimates for the California Current System with uncertainties less than 10 cm are used to solve for a geoid correction field. The derived field increases the consistency between the DOTs and along-track altimetric observations, suggesting it is a useful correction to the gravitational field. The correction is large compared to the dynamic ocean topography, with a magnitude of 15 cm and significant structure, especially near the coast. The results are evidence that modern high-resolution dynamic ocean topography products can be used to improve estimates of the geoid.

  19. A consistent dataset of Antarctic ice sheet topography, cavity geometry, and global bathymetry

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

    Sub-ice shelf circulation and freezing/melting rates in ocean general circulation models depend critically on an accurate and consistent representation of cavity geometry. Existing global or pan-Antarctic data sets have turned out to contain various inconsistencies and inaccuracies. The goal of this work is to compile independent regional fields 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 get the best out of each data set. 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 topography data set (RTopo-1) contains maps for upper and lower ice surface heights, bedrock topography, and consistent masks for open ocean, grounded ice, floating ice, and bare land surface. The data set is available in NetCDF format from the PANGAEA database at doi:10.1594/pangaea.741917.

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

    NASA Astrophysics Data System (ADS)

    Ma, Ting; Zhang, Zhongjie

    2014-11-01

    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.

  1. Dependence of Eemian Greenland temperature reconstructions on the ice sheet topography

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  2. Dependence of Eemian Greenland temperature reconstructions on the ice sheet topography

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  3. Angle resolved ion scattering spectroscopy at surfaces of pure liquids: topography and orientation of molecules.

    PubMed

    Andersson, Gunther

    2005-08-01

    The topography of a liquid surface has not been the subject of experimental research because of a lack of experimental methods. The hereby outlined investigation shows how the topography of a liquid surface can be classified through the angular mode of neutral impact collision ion scattering spectroscopy. It further shows how concentration depth profiles with a high depth resolution are gained. These can be used as the basis to determine quantitatively the orientation of molecules. The substances investigated are the polar solvents formamide and benzyl alcohol. PMID:16189615

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

    NASA Astrophysics Data System (ADS)

    Crain, K.; Holland, A. A.

    2013-12-01

    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.

  5. A Study of the Effects of Seafloor Topography on Tsunami Propagation

    NASA Astrophysics Data System (ADS)

    Ohata, T.; Mikada, H.; Goto, T.; Takekawa, J.

    2011-12-01

    For tsunami disaster mitigation, we consider the phenomena related to tsunami in terms of the generation, propagation, and run-up to the coast. With consideration for these three phenomena, we have to consider tsunami propagation to predict the arrival time and the run-up height of tsunami. Numerical simulations of tsunami that propagates from the source location to the coast have been widely used to estimate these important parameters. When a tsunami propagates, however, reflected and scattered waves arrive as later phases of tsunami. These waves are generated by the changes of water depth, and could influence the height estimation, especially in later phases. The maximum height of tsunami could be observed not as the first arrivals but as the later phases, therefore it is necessary to consider the effects of the seafloor topography on tsunami propagation. Since many simulations, however, mainly focus on the prediction of the first arrival times and the initial height of tsunami, it is difficult to simulate the later phases that are important for the tsunami disaster mitigation in the conventional methods. In this study, we investigate the effects of the seafloor topography on tsunami propagation after accommodating a tsunami simulation to the superposition of reflected and refracted waves caused by the smooth changes of water depths. Developing the new numerical code, we consider how the effects of the sea floor topography affect on the tsunami propagation, comparing with the tsunami simulated by the conventional method based on the liner long wave theory. Our simulation employs the three dimensional in-equally spaced grids in finite difference method (FDM) to introduce the real seafloor topography. In the simulation, we import the seafloor topography from the real bathymetry data near the Sendai-Bay, off the northeast Tohoku region, Japan, and simulate the tsunami propagation over the varying seafloor topography there. Comparing with the tsunami simulated by the conventional method based on the liner long wave theory, we found that the amplitudes of tsunamis are different from each other for the two simulations. The degree of the amplification of the height of tsunami in our method is larger than that in the conventional one. The height of the later phases of the tsunamis shows the discrepancy between the two results. We would like to conclude that the real changes of water depth affect the prediction of tsunami propagation and the maximum height. Because of the effects of the seafloor topography, the amplitude of the later phases is sometimes larger than the former ones. Due to the inclusion of such effects by the real topography, we believe our method lead to a higher accuracy of prediction of tsunami later phases, which would be effective for tsunami disaster mitigation.

  6. Sensitivity of a Barotropic Ocean Model to Perturbations of the Bottom Topography

    E-print Network

    Eugene Kazantsev

    2008-11-07

    In this paper, we look for an operator that describes the relationship between small errors in representation of the bottom topography in a barotropic ocean model and the model's solution. The study shows that the model's solution is very sensitive to topography perturbations in regions where the flow is turbulent. On the other hand, the flow exhibits low sensitivity in laminar regions. The quantitative measure of sensitivity is influenced essentially by the error growing time. At short time scales, the sensitivity exhibits the polynomial dependence on the error growing time. And in the long time limit, the dependence becomes exponential.

  7. Velocity field reconstruction in gravity-driven flow over unknown topography

    NASA Astrophysics Data System (ADS)

    Heining, C.

    2011-03-01

    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.

  8. Modelled sensitivity of the snow regime to topography, shrub fraction and shrub height

    NASA Astrophysics Data System (ADS)

    Ménard, C. B.; Essery, R.; Pomeroy, J.

    2014-01-01

    Recent studies show that shrubs are colonizing higher latitudes and altitudes in the Arctic. Shrubs affect the wind transport, accumulation and melt of snow, but there have been few sensitivity studies of how shrub expansion might affect snowmelt rates and timing. Here, a blowing snow transport and sublimation model is used to simulate premelt snow distributions and a 3-source energy balance model, which calculates vertical and horizontal energy fluxes between the atmosphere, snow, snow-free ground and vegetation, is used to simulate melt. Vegetation is parametrized as shrub cover and the parametrization includes shrub bending and burial in winter and emergence in spring. The models are used to investigate the sensitivity of the snow regime in an upland tundra valley to varying shrub cover and topography. Results show that topography dominates the spatial variability of snow accumulation, which in turn dominates the pre and early melt energy budget. With topography removed from the simulations, modelled snow cover is uniform when there is no vegetation but increasing vegetation introduces spatial variability in snow accumulation which is then decreased as further increases in shrub cover suppress wind-induced redistribution of snow. The domain-averaged simulations of premelt snow accumulation also increases with increasing shrub cover because suppression of blowing snow by shrubs decreases sublimation. In simulations with topography, the increase in snow accumulation and its spatial variability with increasing vegetation is less marked because snow is also held in topography-driven drifts. With topography, the existence of wind-scoured snow-free patches at the onset of snowmelt causes exposed ground to contribute to the energy balance such that sensible, advective and radiative heat fluxes are higher than in the flat domain during this period. However, as snowmelt evolves, differences in the energy budget between runs with and without topography dramatically diminish. These results suggest that, to avoid overestimating the effect of shrub expansion on the energy budget of the Arctic, future large scale investigations should consider wind redistribution of snow, shrub bending and emergence, and sub-grid topography as they affect the variability of snowcover.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

    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.

  10. Network synthesis

    NASA Technical Reports Server (NTRS)

    Brockett, R. W.

    1975-01-01

    A discussion, with numerous examples, on the application of state variable methods to network analysis and synthesis is reported. The state variable point of view is useful in the design of control circuits for regulators because, unlike frequency domain methods, it is applicable to linear and nonlinear problems. The reported are intended as an introduction to this theory.

  11. Evaluating the Social Acceptability of Persons with Habit Disorders: The Effects of Topography, Frequency, and Gender Manipulation

    Microsoft Academic Search

    Douglas W. Woods; R. Wayne Fuqua; Ryan C. Oiitman

    1999-01-01

    In this study, 120 undergraduate students were asked to rate the social acceptability of a male and female who portrayed different habit behaviors (motor tics, vocal tics, Tourette's disorder, and trichotillomania). The portrayals of these behaviors were clinically valid as viewed by mental health professionals. Each habit behavior was portrayed in a variety of frequency\\/topography combinations including low frequency\\/mild topography,

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

    E-print Network

    Texas at Austin. University of

    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

  13. Restoration of floodplain topography by sand-splay complex formation in response to intentional levee breaches, Lower Cosumnes River, California

    Microsoft Academic Search

    Joan L. Florsheim; Jeffrey F. Mount

    2002-01-01

    Restoration of sustainable geomorphic processes that create floodplain topography through development of sand-splay complexes at intentional breaches is one method to promote variability in physical structure needed for habitat restoration. The topography of splay complexes provides a range of floodplain elevations that creates local variability in (i) inundation duration and frequency and depth to ground water that influence riparian vegetation

  14. THE FORMATION HISTORY OF OLYMPUS MONS FROM PALEO-TOPOGRAPHY. L. M. Jozwiak1,2 J. Isherwood2

    E-print Network

    volcano in the solar system. Its volcanic his- tory is intimately tied with the volcanic and geody- namic on the flexural trough surrounding the edifice that pre-date the trough are used to constrain the onset of Olympus. Paleo-topography of the Olympus Mons flexural trough. The concept of paleo-topography is used

  15. The influence of altitude and topography on genetic structure in the long-toed salamander (Ambystoma macrodactulym)

    Microsoft Academic Search

    ANDREW R. GIORDANO; BENJAMIN J. RIDENHOUR; ANDREW STORFER

    2007-01-01

    A primary goal of molecular ecology is to understand the influence of abiotic factors on the spatial distribution of genetic variation. Features including altitudinal clines, topography and landscape characteristics affect the proportion of suitable habitat, influence dispersal patterns, and ultimately structure genetic differentiation among populations. We studied the effects of altitude and topography on genetic variation of long-toed salamanders (

  16. IEEE GEOSCIENCE AND REMOTE SENSING LETTERS, VOL. X, NO. X, NOVEMBER 200X 1 Digital Topography Models for Martian Surfaces

    E-print Network

    Vilalta, Ricardo

    an unsupervised automated classification of topographic features on Mars in order to speed up geomorphic and geologic mapping of the planet. We construct a digital topography model (DTM), a multi-layer grid by classifying and characterizing the topography of a landscape in the Tisia Valles region on Mars. We discuss

  17. High Resolution Mapping and Interpretation of Channel and Floodplain Topography With a Narrow-Beam Terrestrial-Aquatic Lidar

    Microsoft Academic Search

    J. McKean; D. Isaak; D. Tonina; W. Wright; P. Kinzel

    2007-01-01

    Basic description of channel and floodplain topography remains a fundamental challenge for modeling flow and sediment transport or even simply mapping habitat. Standard field wading and boat surveys of stream topography are limited by costs and logistics to relatively small sample reaches and floodplain maps are seldom well- integrated with channel bathymetry. We used the NASA Experimental Advanced Airborne Research

  18. GLUTATHIONE SYNTHESIS

    PubMed Central

    Lu, Shelly C.

    2012-01-01

    BACKGROUND Glutathione (GSH) is present in all mammalian tissues as the most abundant non-protein thiol that defends against oxidative stress. GSH is also a key determinant of redox signaling, vital in detoxification of xenobiotics, regulates cell proliferation, apoptosis, immune function, and fibrogenesis. Biosynthesis of GSH occurs in the cytosol in a tightly regulated manner. Key determinants of GSH synthesis are the availability of the sulfur amino acid precursor, cysteine, and the activity of the rate-limiting enzyme, glutamate cysteine ligase (GCL), which is composed of a catalytic (GCLC) and a modifier (GCLM) subunit. The second enzyme of GSH synthesis is GSH synthetase (GS). SCOPE OF REVIEW This review summarizes key functions of GSH and focuses on factors that regulate the biosynthesis of GSH, including pathological conditions where GSH synthesis is dysregulated. MAJOR CONCLUSIONS GCL subunits and GS are regulated at multiple levels and often in a coordinated manner. Key transcription factors that regulate the expression of these genes include NF-E2 related factor 2 (Nrf2) via the antioxidant response element (ARE), AP-1, and nuclear factor kappa B (NF?B). There is increasing evidence that dysregulation of GSH synthesis contributes to the pathogenesis of many pathological conditions. These include diabetes mellitus, pulmonary and liver fibrosis, alcoholic liver disease, cholestatic liver injury, endotoxemia and drug-resistant tumor cells. GENERAL SIGNIFICANCE GSH is a key antioxidant that also modulates diverse cellular processes. A better understanding of how its synthesis is regulated and dysregulated in disease states may lead to improvement in the treatment of these disorders. PMID:22995213

  19. Retinal Ganglion Cell Topography of Five Species of Ground-Foraging Birds

    Microsoft Academic Search

    Tracy Dolan; Esteban Fernández-Juricic

    2010-01-01

    Birds that forage on the ground have been studied extensively in relation to behavioral trade-offs between foraging and scanning for predators; however, we know little about the topography of their retinas, which can influence how they gather visual information. We characterized the density of retinal ganglion cells across the retina and estimated visual acuity of four Passeriformes (European starling Sturnus

  20. Breast muscle topography and its relationship to muscularity in Pekin ducklings

    E-print Network

    Paris-Sud XI, Université de

    Note Breast muscle topography and its relationship to muscularity in Pekin ducklings Karima A muscles (m. pectoralis superficialis, m. pectoralis profundus) were used to exam- ine their usefulness as predictors or indices of total carcass muscle weight. As much as 65 % of the variation in total carcass

  1. ctoh.legos.obs-mip.fr The Centre for the Topography of Oceans and the

    E-print Network

    ctoh.legos.obs-mip.fr ABSTRACT : The Centre for the Topography of Oceans and the Hydrosphere (CTOH), the Altimeter Data Service of the LEGOS laboratory validates ENVISAT RA2 altimetry, in particular over Antarctic-CNES Symposium, 20 Years of Progress in Radar Altimetry, 24-29 September 2012, Venice, Italy LEGOS/CTOH, 14

  2. Multiscale Biomimetic Topography for the Alignment of Neonatal and Embryonic Stem Cell-Derived Heart Cells

    E-print Network

    Fowlkes, Charless

    Multiscale Biomimetic Topography for the Alignment of Neonatal and Embryonic Stem Cell neonatal mouse cardiomyocytes as well as those derived from human embryonic stem cells. By mimicking is of interest for a wide variety of cell types, including neurons, skeletal, smooth muscle cells, and even

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

    E-print Network

    Zhou, Yaoqi

    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

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

    USGS Publications Warehouse

    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

    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.

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

    USGS Publications Warehouse

    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

    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.

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

    USGS Publications Warehouse

    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

    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.

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

    USGS Publications Warehouse

    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

    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.

  8. SAR interferometry at Venus for topography and change detection Franz J. Meyer a,b,n

    E-print Network

    Sandwell, David T.

    on Earth, their application to Venus could be complicated by phase distortions caused by the thick VenusSAR interferometry at Venus for topography and change detection Franz J. Meyer a,b,n , David T 1 March 2012 Received in revised form 4 October 2012 Accepted 5 October 2012 Keywords: Venus

  9. Shuttle Radar Topography Mission: an innovative approach to shuttle orbital control

    Microsoft Academic Search

    Alberto Foni; David Seal

    2004-01-01

    On February 11, 2000, the space shuttle endeavour lifted off to tackle an ambitious mission: make the most comprehensive map ever of planet Earth. The successful 11-day Shuttle Radar Topography Mission produced the most complete terrain map of the world. Radar inteferometry was used to derive surface elevation by calculating the differences between measurements taken from slightly different locations.The payload

  10. Transformations of the retinal topography along the visual pathway of the chicken

    Microsoft Academic Search

    Ute Rager; Giinter Rager; Alexa Kabiersch

    1988-01-01

    It is still unclear how the retinotectal map of the chick is formed during development. In particular, it is not yet known whether or not the organization of fibres plays a role in the formation of this map. In order to contribute to the solution of this problem, we analysed the representation of the retinal topography at closely spaced intervals

  11. Human Corneal Limbal-Epithelial Cell Response to Varying Silk Film Geometric Topography In Vitro

    PubMed Central

    Lawrence, Brian D.; Pan, Zhi; Liu, Aihong; Kaplan, David L.; Rosenblatt, Mark I.

    2012-01-01

    Silk fibroin films are a promising class of biomaterials that have a number of advantages for use in ophthalmic applications due to their transparent nature, mechanical properties and minimal inflammatory response upon implantation. Freestanding silk films with parallel line and concentric ring topographies were generated for in vitro characterization of human corneal limbal-epithelial (HCLE) cell response upon differing geometric patterned surfaces. Results indicated that silk film topography significantly affected initial HCLE culture substrate attachment, cellular alignment, cell-to-cell contact formation, actin cytoskeleton alignment, and focal adhesion (FA) localization. Most notably, parallel line patterned surfaces displayed a 36%–54% increase on average in initial cell attachment, which corresponded to an over 2-fold increase in FA localization when compared to other silk film surfaces and controls. In addition, distinct localization of FA formation was observed along the edges for all patterned silk film topographies. In conclusion, silk film feature topography appears to help direct corneal epithelial cell response and cytoskeleton development, especially in regards to FA distribution, in vitro. PMID:22705042

  12. Carbon Contamination Topography Analysis of EUV Masks Yu-Jen Fan1

    E-print Network

    Carbon Contamination Topography Analysis of EUV Masks Yu-Jen Fan1 , Leonid Yankulin1 , Petros ABSTRACT The impact of carbon contamination on extreme ultraviolet (EUV) masks is significant due to throughput loss and potential effects on imaging performance. Current carbon contamination research primarily

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

    ERIC Educational Resources Information Center

    O'Dell, Gary; Gonzalez-Espada, Wilson

    2011-01-01

    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…

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

    NASA Technical Reports Server (NTRS)

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

    1988-01-01

    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.

  15. Spectral analysis of tsunami waves: Separation of source and topography effects

    Microsoft Academic Search

    Alexander B. Rabinovich

    1997-01-01

    A new approach is proposed to separate the influence of source and topography in observed tsunami spectra and to reconstruct the initial source spectrum. The method assumes a linear tide gauge response to external forcing and is based on comparative analysis of tsunami and background spectra. Evaluation of the ratio of tsunami to background spectra gives functional characteristics that are

  16. 3D SEM for surface topography quantification - a case study on dental surfaces

    NASA Astrophysics Data System (ADS)

    Glon, F.; Flys, O.; Lööf, P.-J.; Rosén, B.-G.

    2014-03-01

    3D analysis of surface topography is becoming a more used tool for industry and research. New ISO standards are being launched to assist in quantifying engineering surfaces. The traditional optical measuring instrumentation used for 3D surface characterization has been optical interferometers and confocal based instrumentation. However, the resolution here is limited in the lateral dimension to the wavelength of visible light to about 500 nm. The great advantage using the SEM for topography measurements is the high flexibility to zoom from low magnifications and locating interesting areas to high magnification of down to nanometer large surface features within seconds. This paper presents surface characterization of dental implant micro topography. 3D topography data was created from SEM images using commercial photogrammetric software. A coherence scanning interferometer was used for reference measurements to compare with the 3D SEM measurements on relocated areas. As a result of this study, measurements emphasizes that the correlation between the accepted CSI measurements and the new technology represented by photogrammetry based on SEM images for many areal characterization parameters are around or less than 20%. The importance of selecting sampling and parameter sensitivity to varying sampling is high-lighted. Future work includes a broader study of limitations of the photogrammetry technique on certified micro-geometries and more application surfaces at different scales.

  17. Push in South of the Hellas Basin Showing Topography from MOLA

    NSDL National Science Digital Library

    Tom Biddlecome

    1999-11-22

    Zoom into the region of Mars just south of the Hellas Basin showing topography data from MOLA. Blue tones represent elevations of less than 2 kilometers, while reddish tones are greater than about 2.8 kilometers, relative to the mean equatorial height of Mars.

  18. Satellites images, digitized topography, and the recognition of the Xela Caldera, Quezaltenango Valley, Guatemala

    Microsoft Academic Search

    D. Foley; A. McEwen; W. Duffield; G. Heiken

    1992-01-01

    The authors propose, based on reconnaissance geology studies and interpretation of landforms as depicted by Landsat Thematic Mapper (TM) images combined with digitized topography, that the Quezaltenango basin of Guatemala is part of a caldera. The Quezaltenango basin is an elliptical depression, about 12 by 25 km and about 500 m deep. The proposed Xela Caldera extends beyond the basin

  19. Global rate and spectral characteristics of internal gravity wave generation by geostrophic flow over topography

    E-print Network

    Naveira Garabato, Alberto

    Hemisphere produced 92% of the lee wave energy, with the Southern Ocean dominating. Strength of the bottom in the Indian Ocean where extremely rough topography produced strong lee wave generation despite only moderate bottom flows. The results imply about one half of the mechanical power input to the ocean general

  20. Evolution of the topography in the Southern Alps of New Zealand

    Microsoft Academic Search

    F. Herman; J. Braun

    2006-01-01

    We will present new insights into the evolution of the topography in the Southern Alps of New Zealand (a young, active, very rapid and glaciated orogen) using landscape evolution models. We first use a two- dimensional fluvial erosion model coupled with an inversion algorithm (the Neighbourhood Algorithm [Sambridge 1999] ) to explore the fluvial response of the landscape during a

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

    E-print Network

    Klein, Stanley

    Corneal Topography: A review, new ANSI standards and problems to solve Stanley A. Klein School based instruments is presented. 2. a summary of and commentary on the newly issued ANSI standards topographers" by the ANSI standard), has the advantage of being able to measure corneal thickness as well

  2. Full chip implant correction with wafer topography OPC modeling in 2x nm bulk technologies

    NASA Astrophysics Data System (ADS)

    Michel, J.-C.; Le Denmat, J.-C.; Sungauer, E.; Robert, F.; Yesilada, E.; Armeanu, A.-M.; Entradas, J.; Sturtevant, J. L.; Do, T.; Granik, Y.

    2013-09-01

    Ionic implantation photolithography step considered to be non critical started to be influenced by unwanted overexposure by wafer topography with technology node downscaling evolution [1], [2]. Starting from 2xnm technology nodes, implant patterns modulated on wafer by classical implant proximity effects are also influenced by wafer topography which can cause drastic pattern degradation [2], [3]. This phenomenon is expected to be attenuated by the use of anti-reflecting coating but it increases process complexity and involves cost and cycle time penalty. As a consequence, computational lithography solutions are currently under development in order to correct wafer topographical effects on mask [3]. For ionic implantation source Drain (SD) on Silicon bulk substrate, wafer topography effects are the consequence of active silicon substrate, poly patterns, STI stack, and transitions between patterned wafer stack. In this paper, wafer topography aware OPC modeling flow taking into account stack effects for bulk technology is presented. Quality check of this full chip stack aware OPC model is shown through comparison of mask computational verification and known systematic defectivity on wafer. Also, the integration of topographical OPC model into OPC flow for chip scale mask correction is presented with quality and run time penalty analysis.

  3. Effects of micropitted/nanotubular titania topographies on bone mesenchymal stem cell osteogenic differentiation.

    PubMed

    Zhao, Lingzhou; Liu, Li; Wu, Zhifen; Zhang, Yumei; Chu, Paul K

    2012-03-01

    Micro/nanotopographical modification of biomaterials constitutes a promising approach to direct stem cell osteogenic differentiation to promote osseointegration. In this work, titania nanotubes (NTs) 25 and 80 nm in size with the acid-etched Ti topography (AcidTi) and hierarchical hybrid micropitted/nanotubular topographies (Micro/5VNT and Micro/20VNT) are produced to mimic the structure of the natural bone extracellular matrix (ECM). The effects on bone mesenchymal stem cell (MSC) osteogenic differentiation are studied systematically by various microscopic and biological characterization techniques. Cell adhesion is assayed by nucleus fluorescence staining and cell proliferation is studied by CCK-8 assay and ?ow cytometry. Osteogenic differentiation is assayed by alkaline phosphatase (ALP) expression, collagen secretion, matrix mineralization, and quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis on the osteogenesis related gene expression. All the topographies are observed to induce MSC osteogenic differentiation in the absence of osteogenic supplements. The nanotube surfaces significantly promote cell attachment and spread, collagen secretion and ECM mineralization, as well as osteogenesis-related gene expression. Among them, Micro/20VNT shows the best ability to simultaneously promote MSC proliferation and osteogenic differentiation. Our results unambiguously demonstrate their excellent ability to support MSC proliferation and induce MSC osteogenic differentiation, especially those with the micropitted topography. PMID:22204980

  4. Induced thermal stress fields for three-dimensional distortion control of Si wafer topography

    Microsoft Academic Search

    Charles D. Schaper; Been-Der Chen; R. Fabian W. Pease

    2004-01-01

    Localized, controlled heating can induce a thermal stress field in silicon wafers and displace the surface topography in three dimensions, which is useful for nanoscale regulation of overlay in microcontact printing systems. Simulation and experimental results are presented to demonstrate the use of a thermal array consisting of a dense distribution of independent heating elements to locally displace silicon wafer

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

    PubMed

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

    2012-03-01

    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 variant regularization to optimize depth discrimination. The 3D optical topography images suggest that similar brain regions are activated in infants and adults. Images were presented showing the distribution of activation in a plane parallel to the surface, as well as changes in activation with depth. The time-course of activation was followed in the pixel which demonstrated the largest change, showing that changes could be measured with high temporal resolution. These results suggest that infants a few months old have regions which are specialized for reacting to human activity, and that these subtle changes can be effectively analysed using 3D optical topography. PMID:22330053

  6. Progress in mapping bed topography with OIB and other data in Greenland and Antarctica (Invited)

    NASA Astrophysics Data System (ADS)

    Rignot, E. J.; Morlighem, M.; Mouginot, J.; Seroussi, H.; Larour, E. Y.

    2013-12-01

    Bed topography beneath ice sheets is traditionally mapped using radar echo sounding profilers combined with a geostatistical interpolation technique to fill in data gaps and produce an output on a regular grid. Sea floor bathymetry is traditionally mapped with sonar profilers and in more recent years with multibeam sonars, except beneath floating ice shelves. NASA OIB has placed a strong focus on improving the mapping of glacier bed topography and sea floor bathymetry. In Greenland, we will show the current, fundamental limitations of radar echo sounding and the necessity to come up with new approaches. A promising approach is to combine the data with surface ice velocity data and infer ice thickness (and bed topography) on the basis of mass conservation. Examples in Greenland and Antarctica show that the method is robust versus errors from off-nadir returns, surface mass balance, ice thickening, temporal change in velocity and depth-average velocity versus surface velocity. The output products are bed topography maps at 350 m resolution, with 40 m vertical precision, which compare favorably to the best mapping achievable with radar sounding alone. Beneath floating ice shelves, OIB acquired airborne gravity data to infer sea floor bathymetry. Example results in Greenland and Antarctica demonstrate that many of the output products reveal major surprises and the fundamental importance of extending these measurements to other ice shelves and eventually to all floating ice shelves.

  7. Instrumentation for the measurement of shallow seabed topography by a fishing echo sounder

    Microsoft Academic Search

    Katsumori HATANAKA; Masaaki WADA; Minoru KOTAKI

    2005-01-01

    The multi-beam bathymetry can provide a detailed view of the seafloor and is successfully utilized in oceanography; however its expense makes it impractical for many uses. In this paper, the authors present a low-priced system for surveying shallow sea bottom topography by using a fishing echo sounder in such a way that the many areas of the industry in which

  8. Asynchronous inputs alter excitability, spike timing, and topography in primary auditory cortex

    E-print Network

    Allen, Jont

    Asynchronous inputs alter excitability, spike timing, and topography in primary auditory cortex stimulation was associated with asynchronous activation of the high and low frequency regions of A1. This set., 2002; Stryker and Strickland, 1984; Wang et al., 1995). Behaviorally relevant sensory and motor events

  9. Asynchronous inputs alter excitability, spike timing, and topography in primary auditory cortex

    E-print Network

    Kilgard, Michael P.

    Asynchronous inputs alter excitability, spike timing, and topography in primary auditory cortex nucleus basalis stimulation was associated with asynchronous activation of the high and low frequency and motor events are marked by increased activity in nucleus basalis (NB), which projects to the entire

  10. Behavioral/Systems/Cognitive Optical Imaging of SI Topography in Anesthetized and

    E-print Network

    Roe, Anna Wang

    in the somatosensory cortex reflects a "body map" is well supported. However, a recent study has called into question traditional views of somatosensory cortical maps (Chen et al., 2003). This study demonstrated that corticalBehavioral/Systems/Cognitive Optical Imaging of SI Topography in Anesthetized and Awake Squirrel

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

    ERIC Educational Resources Information Center

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

    2009-01-01

    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…

  12. Under consideration for publication in J. Fluid Mech. 1 Nonlinear dynamics over rough topography

    E-print Network

    Vanneste, Jacques

    is confined within a thin bottom boundary layer, so that it is through a new bottom boundary condition of nonlinear periodic and solitary waves in continuously stratified fluid over topography. The influence, and solitary waves. The present paper is similar in spirit to those of Volosov and Zdhanov. Its main novel

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

    Microsoft Academic Search

    Richard Essery; Danny Marks

    2007-01-01

    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 surface to be flat on subgrid scales. For four areas in North America,

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

    Microsoft Academic Search

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

    1990-01-01

    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

  15. Determination of the topography and biometry of chlorosomes by atomic force microscopy

    Microsoft Academic Search

    Asunción Martinez-Planells; Juan B. Arellano; Carles M. Borrego; Carmen López-Iglesias; Frederic Gich; Jesús Garcia-Gil

    2002-01-01

    Isolated chlorosomes of several species of filamentous anoxygenic phototrophic bacteria (FAPB) and green sulfur bacteria (GSB) were examined by atomic force microscopy (AFM) to characterize their topography and biometry. Chlorosomes of Chloroflexusaurantiacus, Chloronema sp., and Chlorobium (Chl.) tepidum exhibited a smooth surface, whereas those of Chl. phaeobacteroides and Chl. vibrioforme showed a rough one. The potential artifactual nature of the

  16. Spatial and temporal patterns of Australian dynamic topography from River Profile Modeling

    NASA Astrophysics Data System (ADS)

    Czarnota, K.; Roberts, G. G.; White, N. J.; Fishwick, S.

    2014-02-01

    Despite its importance, the temporal and spatial evolution of continental dynamic topography is poorly known. Australia's isolation from active plate boundaries and its rapid northward motion within a hot spot reference frame make it a useful place to investigate the interplay between mantle convection, topography, and drainage. Offshore, dynamic topography is relatively well constrained and can be accounted for by Australia's translation over the mantle's convective circulation. To build a database of onshore constraints, we have analyzed an inventory of longitudinal river profiles, which is sensitive to uplift rate history. Using independently constrained erosional parameters, we determine uplift rates by minimizing the misfit between observed and calculated river profiles. Resultant fits are excellent and calculated uplift histories match independent geologic constraints. We infer that western and central Australia underwent regional uplift during the last 50 Myr and that the Eastern Highlands have been uplifted in two stages. The first stage from 120 to 80 Ma, coincided with rifting along the eastern margin and its existence is supported by thermochronological measurements. A second stage occurred at 80-10 Ma, formed the Great Escarpment, and coincided with Cenozoic volcanism. The relationship between topography, gravity anomalies, and shear wave tomographic models suggest that regional elevation is supported by temperature anomalies within the lithosphere's thermal boundary layer. Morphology and stratigraphy of the Eastern Highlands imply that these anomalies have been coupled to the base of the plate during Australia's northward motion over the last 70 Myr.

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

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  18. Links between topography, wind, deflation, lakes and dust: The case of the Bodele Depression, Chad

    E-print Network

    Washington, Richard

    Links between topography, wind, deflation, lakes and dust: The case of the Bode´le´ Depression´le´ Depression, Chad is the planet's largest single source of dust. Deflation from the Bode´le´ could be seen wetter phases, such as the Holocene pluvial. Winds may therefore have helped to create the depression

  19. Analysis of Second Harmonic Generation of a KDP crystal based on multi-scale topography simulation

    NASA Astrophysics Data System (ADS)

    Liu, Hai Tao; Su, Rui Feng; Sun, Ya Zhou; Wang, He Ran

    2015-04-01

    The surface topography of the supporting frame of a KDP crystal is studied, as well as its influence on the deformation and stress of the KDP crystal, together with the Second Harmonic Generation (SHG). A comprehensive model incorporating principles of multi-scale surface analysis, mechanics, and optics is proposed, and it is applied to investigate the surface topography of the supporting frame, the deformation and stress of the KDP crystal, as well as the SHG efficiency. The surface topography is analyzed using fractural theory, and then classified according to its multi-scale specifics. Based on the surface analysis results, the mounting configuration of the KDP crystal is modeled and analyzed in global and local modes, respectively, using the Finite Element Method (FEM). Moreover, deformation and stress of the KDP crystal that is induced by the mechanical mounting is studied using the FEM, together with the effects of the surface topography on them. Furthermore, the change of the refractive index that induced by the deformation and stress are calculated, respectively, the results of which is applied to studied the phase mismatch, and the SHG efficiency considering the phase mismatch is eventually obtained. The numerical results demonstrate that the frame surface with multi-scale dimensions has diverse influences on the distortion and stress, as well as the SHG efficiency.

  20. Cell adhesion on polyelectrolyte multilayer coated polydimethylsiloxane surfaces with varying topographies.

    PubMed

    Kidambi, Srivatsan; Udpa, Natasha; Schroeder, Stacey A; Findlan, Robert; Lee, Ilsoon; Chan, Christina

    2007-08-01

    This article demonstrates that the micro-topography of the surface with respect to the pattern size and pitch influences cell adhesion and proliferation. Extensive research has shown the dependence of cell proliferation on substrate chemistry, but the influence of substrate topography on cell attachment has only recently been appreciated. To evaluate the effect of substrate physical properties (i.e., periodic microstructures) on cell attachment and morphology, we compared the response of several cell types (fibroblasts, HeLa, and primary hepatocytes) cultured on various polydimethylsiloxane (PDMS) patterns. PDMS has been used as an artificial construct to mimic biological structures. Although PDMS is widely used in biomedical applications, membrane technology, and microlithography, it is difficult to maintain cells on PDMS for long periods, and the polymer has proved to be a relatively inefficient substrate for cell adhesion. To improve adhesion, we built polyelectrolyte multilayers (PEMs) on PDMS surfaces to increase surface wettability, thereby improving attachment and spreading of the cells. Micrographs demonstrate the cellular response to physical parameters, such as pattern size and pitch, and suggest that surface topography, in part, regulates cell adhesion and proliferation. Therefore, varying the surface topography may provide a method to influence cell attachment and proliferation for tissue-engineering applications. PMID:17518734

  1. 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...

  2. Effects of topography on tropical lower montane forests under different geological conditions on Mount Kinabalu, Borneo

    Microsoft Academic Search

    Masaaki Takyu; Shin-Ichiro Aiba; Kanehiro Kitayama

    2002-01-01

    Species composition and forest structure change with topography.However, mechanisms for topographical vegetation changes are still not wellunderstood, because a topographical gradient is a complex environmentalgradientinclusive of many factors. The foot of Mt. Kinabalu is covered with three typesof geological substrates, i.e. Quaternary and Tertiary sedimentary rocks andultrabasic (serpentine) rock. Quaternary and Tertiary sedimentaryrocks are different in site age, but controlled

  3. Functions of maladaptive behavior in intellectual and developmental disabilities: behavior categories and topographies.

    PubMed

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

    2012-01-01

    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 completed by direct care staff for one target behavior for each of 115 adults with varying degrees of intellectual disabilities. In the first step we examined the functional properties of three broad behavior categories (self-injurious behavior [SIB], stereotypic behavior, and aggressive/destructive behavior). Consistent with previous research stereotyped behaviors and SIB had significantly higher QABF Nonsocial (i.e., automatic positive reinforcement or self-stimulation) subscale scores than aggressive behavior, while none of the other subscales showed differences across the three behavior categories. Contrary to earlier studies, escape (or negative social reinforcement) was an important function not only for aggressive behavior, but also for SIB and stereotypies. A second analysis examined functional properties depending on two factors: the behavior topography (hitting vs. non-hitting behaviors) and their respective behavior category (SIB vs. aggression). SIB topographies had higher ratings than aggressive behavior on the QABF Nonsocial subscale. Of the five QABF subscales, only the subscale Nonsocial differed between categories of maladaptive behavior. Furthermore it was the behavior categories rather than the topographies that determined functional properties. PMID:22750358

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

    E-print Network

    Sutherland, Bruce

    1 Large-amplitude internal wave generation in the lee of step-shaped topography B. R. Sutherland, nonlinear effects are more important. In particular, large-amplitude waves are not necessarily "passively University of Alberta, Edmonton, Canada. Short title: LARGE-AMPLITUDE INTERNAL WAVE GENERATION . . . #12

  5. Managing Construction Operations Visually: 3-D Techniques for Complex Topography and Restricted Visibility

    ERIC Educational Resources Information Center

    Rodriguez, Walter; Opdenbosh, Augusto; Santamaria, Juan Carlos

    2006-01-01

    Visual information is vital in planning and managing construction operations, particularly, where there is complex terrain topography and salvage operations with limited accessibility and visibility. From visually-assessing site operations and preventing equipment collisions to simulating material handling activities to supervising remotes sites…

  6. An assessment of shuttle radar topography mission digital elevation data for studies of volcano morphology

    E-print Network

    Wright, Robert

    An assessment of shuttle radar topography mission digital elevation data for studies of volcano's volcanoes. Although these data were acquired with a nominal spatial resolution of 30 m, such data are only available for volcanoes located within the U.S.A. and its Territories. For the overwhelming majority

  7. Surface topography analysis in high speed finish milling inclined hardened steel

    Microsoft Academic Search

    C. K. Toh

    2004-01-01

    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

  8. Influence of Measurement Setting and Home Smoking Policy on Smoking Topography

    PubMed Central

    June, Kristie M.; Norton, Kaila J.; Rees, Vaughan W.; O’Connor, Richard J.

    2011-01-01

    While cigarette puffing style, measured by smoking topography, is highly variable between individuals, smoking behavior or style tends to vary relatively little within individuals. Recent research has demonstrated that certain situational factors may produce variation in smoking topography, including location of smoking. Smoking topography directly observed by researchers in a laboratory may differ from that indirectly observed via portable measurement devices at participants’ homes. The introduction of clean indoor air laws may also influence smokers’ puffing styles, as smokers modify their smoking topography to ensure a quicker, more efficient smoking style. The goal of this analysis was to examine whether directly observed laboratory measures are representative of indirectly observed smoking behavior and to examine the influence of smokers’ preference for indoor or outdoor home smoking on puffing style. Overall, participants smoked more intensively in the directly observed setting than when indirectly observed setting in terms of total volume intake, inter-puff interval, and total time spent smoking. This difference was most pronounced among individuals who reported smoking indoors when at home. The data suggest that adherence to an indoor home smoking policy may further influence an individual’s smoking behavior. PMID:21862228

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

    Microsoft Academic Search

    Etienne Decencière; Dominique Jeulin

    2001-01-01

    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

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

    USGS Publications Warehouse

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

    2013-01-01

    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.

  11. Topography of the Calabria subduction zone (southern Italy): Clues for the origin of Mt. Etna

    Microsoft Academic Search

    C. Faccenna; P. Molin; B. Orecchio; V. Olivetti; O. Bellier; F. Funiciello; L. Minelli; C. Piromallo; A. Billi

    2011-01-01

    Calabria represents an ideal site to analyze the topography of a subduction zone as it is located on top of a narrow active Wadati-Benioff zone and shows evidence of rapid uplift. We analyzed a pattern of surface deformation using elevation data with different filters and showed the existence of a long wavelength (>100 km) relatively positive topographic signal at the

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

    Microsoft Academic Search

    Mark A. Wieczorek; Maria T. Zuber

    2004-01-01

    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

  13. Internal Structure and Early Thermal Evolution of Mars from Mars Global Surveyor Topography and Gravity

    Microsoft Academic Search

    Maria T. Zuber; Sean C. Solomon; Roger J. Phillips; David E. Smith; G. Leonard Tyler; Oded Aharonson; Georges Balmino; W. Bruce Banerdt; James W. Head; Catherine L. Johnson; Frank G. Lemoine; Patrick J. McGovern; Gregory A. Neumann; David D. Rowlands; Shijie Zhong

    2000-01-01

    Topography and gravity measured by the Mars Global Surveyor have enabled determination of the global crust and upper mantle structure of Mars. The planet displays two distinct crustal zones that do not correlate globally with the geologic dichotomy: a region of crust that thins progressively from south to north and encompasses much of the southern highlands and Tharsis province and

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

    NASA Technical Reports Server (NTRS)

    Smith, David E.; Zuber, Maria T.

    1999-01-01

    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.

  15. Topography- and management-mediated resource gradients maintain rare and common plant diversity around paddy terraces.

    PubMed

    Uematsu, Yuta; Ushimaru, Atushi

    2013-09-01

    Examining the causes of interspecific differences in susceptibility to bidirectional land-use changes (land abandonment and use-intensification) is important for understanding the mechanisms of global biodiversity loss in agricultural landscapes. We tested the hypothesis that rare (endangered) plant species prefer wet and oligotrophic areas within topography- and management-mediated resource (soil water content, nutrient, and aboveground biomass) gradients, making them more susceptible to both abandonment and use-intensification of agricultural lands. We demonstrated that topography and management practices generated resource gradients in seminatural grasslands around traditional paddy terraces. Terraced topography and management practices produced a soil moisture gradient within levees and a nutrient gradient within paddy terraces. Both total and rare species diversity increased with soil water content. Total species diversity increased in more eutrophied areas with low aboveground biomass, whereas rare species diversity was high under oligotrophic conditions. Rare and common species were differentially distributed along the human-induced nutrient gradient, with rare species preferring wet, nutrient-poor environments in the agricultural landscapes studied. We suggest that conservation efforts should concentrate on wet, nutrient-poor areas within such landscapes, which can be located easily using land-use and topography maps. This strategy would reduce the costs of finding and conserving rare grassland species in a given agricultural landscape. PMID:24147408

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

    ERIC Educational Resources Information Center

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

    2012-01-01

    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…

  17. Interpreting layer thickness advection in terms of eddy-topography interaction

    NASA Astrophysics Data System (ADS)

    Liu, Chuanyu; Köhl, Armin; Stammer, Detlef

    2014-09-01

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

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

    PubMed Central

    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

    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

  19. A critical assessment of viscous models of trench topography and corner flow

    NASA Technical Reports Server (NTRS)

    Zhang, J.; Hager, B. H.; Raefsky, A.

    1984-01-01

    Stresses for Newtonian viscous flow in a simple geometry (e.g., corner flow, bending flow) are obtained in order to study the effect of imposed velocity boundary conditions. Stress for a delta function velocity boundary condition decays as 1/R(2); for a step function velocity, stress goes as 1/R; for a discontinuity in curvature, the stress singularity is logarithmic. For corner flow, which has a discontinuity of velocity at a certain point, the corresponding stress has a 1/R singularity. However, for a more realistic circular-slab model, the stress singularity becomes logarithmic. Thus the stress distribution is very sensitive to the boundary conditions, and in evaluating the applicability of viscous models of trench topography it is essential to use realistic geometries. Topography and seismicity data from northern Hoshu, Japan, were used to construct a finite element model, with flow assumed tangent to the top of the grid, for both Newtonian and non-Newtonian flow (power law 3 rheology). Normal stresses at the top of the grid are compared to the observed trench topography and gravity anomalies. There is poor agreement. Purely viscous models of subducting slables with specified velocity boundary conditions do not predict normal stress patterns compatible with observed topography and gravity. Elasticity and plasticity appear to be important for the subduction process.

  20. A model expansion criterion for treating surface topography in ray path calculations using the eikonal equation

    NASA Astrophysics Data System (ADS)

    Ma, Ting; Zhang, Zhongjie

    2014-04-01

    Irregular surface topography has revolutionized how seismic traveltime is calculated and the data are processed. There are two main schemes for dealing with an irregular surface in the seismic first-arrival traveltime calculation: (1) expanding the model and (2) flattening the surface irregularities. In the first scheme, a notional infill medium is added above the surface to expand the physical space into a regular space, as required by the eikonal equation solver. Here, we evaluate the chosen propagation velocity in the infill medium through ray path tracking with the eikonal equation-solved traveltime field, and observe that the ray paths will be physically unrealistic for some values of this propagation velocity. The choice of a suitable propagation velocity in the infill medium is crucial for seismic processing of irregular topography. Our model expansion criterion for dealing with surface topography in the calculation of traveltime and ray paths using the eikonal equation highlights the importance of both the propagation velocity of the infill physical medium and the topography gradient.

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

    ERIC Educational Resources Information Center

    Barnes, Clarissa S.; Rehfeldt, Ruth Anne

    2013-01-01

    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,…

  2. A Topography of Collaboration: Methodology, Identity and Community in Self-Study of Practice Research

    ERIC Educational Resources Information Center

    Hamilton, Mary Lynn; Pinnegar, Stefinee

    2013-01-01

    Through the use of the metaphoric tool of topography, two educational researchers explore the development of their understanding of collaboration in self-study of teacher education practices research. The researchers communicate their perceptions through the presentation of four topographic moments. Each topographic moment is represented by a poem…

  3. Thermal Model of Europa: Calculating the Effects of Surface Topography and Radiation from Jupiter

    Microsoft Academic Search

    Kristen Bennett; D. Paige; P. Hayne; B. Greenhagen; P. Schenk

    2010-01-01

    Europa's surface temperature distribution results from global effects such as insolation and heat flow, as well as local topography and possibly active tectonic processes. Accurate surface temperature models will greatly benefit future orbital investigations searching for global-scale variations in heat flow and local thermal anomalies resulting from frictional heating on faults or diapirs (Paige et al, this meeting). At the

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

    Microsoft Academic Search

    Maoyi Huang; Xu Liang; L. Ruby Leung

    2008-01-01

    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

  5. High Resolution SAR Interferometry: Influence of Local Topography in the Context of Glacier Monitoring

    Microsoft Academic Search

    G. Vasile; I. Petillot; A. Julea; E. Trouve; P. Bolon; L. Bombrun; M. Gay; T. Landes; P. Grussenmeyer; J.-M. Nicolas

    2006-01-01

    SAR interferometric data offers the opportu- nity to measure temperate glacier surface topography and displacement between the two acquisitions. Recently, reliable estimates of the phase gradient given by interferogram local frequencies become mandatory with the increase of the SAR resolution. In this paper, an original 2-step method for estimating local frequencies is proposed. The 2D phase signal is considered to

  6. High Resolution SAR Interferometry: influence of local topography in the context of glacier monitoring

    Microsoft Academic Search

    G. Vasile; I. Petillot; A. Julea; E. Trouve; L. Bombrun; M. Gay; T. Landes; P. Grussenmeyer; J.-M. Nicolas; Ecole Nationale

    2008-01-01

    SAR interferometric data offers the opportu- nity to measure temperate glacier surface topography and displacement between the two acquisitions. Recently, reliable estimates of the phase gradient given by interferogram local frequencies become mandatory with the increase of the SAR resolution. In this paper, an original 2-step method for estimating local frequencies is proposed. The 2D phase signal is considered to

  7. 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...

  8. The use of spectral analysis-based exact solutions to characterize topography-controlled groundwater flow

    NASA Astrophysics Data System (ADS)

    Marklund, Lars; Wörman, Anders

    2011-12-01

    Spectral analysis enhances the ability to analyze groundwater flow at a steady state by separating the top boundary condition into its periodic forms. Specifically, spectral analysis enables comparisons of the impact of individual spatial scales on the total flow field. New exact spectral solutions are presented for analyzing 3D groundwater flow with an arbitrarily shaped top boundary. These solutions account for depth-decaying, anisotropic and layered permeability while utilizing groundwater flux or the phreatic surface as a top boundary condition. Under certain conditions, groundwater flow is controlled by topography. In areas where the groundwater flow is controlled by the topography, the unknown water table is often approximated by the topography. This approximation induces a systematic error. Here, the optimal resolution of digital elevation models (DEMs) is assessed for use as a top boundary in groundwater flow models. According to the analysis, the water-table undulation is smoother than the topography; therefore, there is an upper limit to the resolution of DEMs that should be used to represent the groundwater surface. The ability to represent DEMs of various spectral solutions was compared and the results indicate that the fit is strongly dependent on the number of harmonics in the spectral solution.

  9. Representing Topography with Second-Degree Bivariate Polynomial Functions Fitted by Least Squares.

    ERIC Educational Resources Information Center

    Neuman, Arthur Edward

    1987-01-01

    There is a need for abstracting topography other than for mapping purposes. The method employed should be simple and available to non-specialists, thereby ruling out spline representations. Generalizing from univariate first-degree least squares and from multiple regression, this article introduces bivariate polynomial functions fitted by least…

  10. Impacts of recreational SCUBA diving at sites with different reef topographies

    Microsoft Academic Search

    Anthony B. Rouphael; Graeme J. Inglis

    1997-01-01

    Increased participation in marine recreation and tourism has been accompanied by concern for the impacts that these activities have on coral reef environments. We investigated how the topography of coral reef dive sites influences the type and amount of damage done by SCUBA divers to living corals. Independent observations were made on 150 qualified SCUBA divers at six dive sites

  11. Under consideration for publication in J. Fluid Mech. 1 Transcritical rotating flow over topography

    E-print Network

    Esler, Gavin

    , and the (, ) regime diagram is found to give good qualitative and quantitative predictions of flow patterns at finite analysis reveals that transcritical flow is likely to be ubiquitious in the ocean and atmosphere (eUnder consideration for publication in J. Fluid Mech. 1 Transcritical rotating flow over topography

  12. Interplay between faulting and base level in the development of Himalayan frontal fold topography

    E-print Network

    of an underlying thrust fault system, provided we understand the factors that shape that topography. Here we that this metric may be used to infer variations in fault dip at depth. In these frontal fold settings, high slip to basins, the firstorder controls on relief generation, and reconstructions of regional tectonic history

  13. Soil resources and topography shape local tree community structure in tropical forests

    PubMed Central

    Baldeck, Claire A.; Harms, Kyle E.; Yavitt, Joseph B.; John, Robert; Turner, Benjamin L.; Valencia, Renato; Navarrete, Hugo; Davies, Stuart J.; Chuyong, George B.; Kenfack, David; Thomas, Duncan W.; Madawala, Sumedha; Gunatilleke, Nimal; Gunatilleke, Savitri; Bunyavejchewin, Sarayudh; Kiratiprayoon, Somboon; Yaacob, Adzmi; Supardi, Mohd N. Nur; Dalling, James W.

    2013-01-01

    Both habitat filtering and dispersal limitation influence the compositional structure of forest communities, but previous studies examining the relative contributions of these processes with variation partitioning have primarily used topography to represent the influence of the environment. Here, we bring together data on both topography and soil resource variation within eight large (24–50 ha) tropical forest plots, and use variation partitioning to decompose community compositional variation into fractions explained by spatial, soil resource and topographic variables. Both soil resources and topography account for significant and approximately equal variation in tree community composition (9–34% and 5–29%, respectively), and all environmental variables together explain 13–39% of compositional variation within a plot. A large fraction of variation (19–37%) was spatially structured, yet unexplained by the environment, suggesting an important role for dispersal processes and unmeasured environmental variables. For the majority of sites, adding soil resource variables to topography nearly doubled the inferred role of habitat filtering, accounting for variation in compositional structure that would previously have been attributable to dispersal. Our results, illustrated using a new graphical depiction of community structure within these plots, demonstrate the importance of small-scale environmental variation in shaping local community structure in diverse tropical forests around the globe. PMID:23256196

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

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

    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 variant regularization to optimize depth discrimination. The 3D optical topography images suggest that similar brain regions are activated in infants and adults. Images were presented showing the distribution of activation in a plane parallel to the surface, as well as changes in activation with depth. The time-course of activation was followed in the pixel which demonstrated the largest change, showing that changes could be measured with high temporal resolution. These results suggest that infants a few months old have regions which are specialized for reacting to human activity, and that these subtle changes can be effectively analysed using 3D optical topography.

  15. Project EARTH-11-ABW1: Plate flexure, dynamic topography and global changes in sea-level

    E-print Network

    Henderson, Gideon

    the Late Cretaceous is a source of tectonic subsidence in sedimentary basins of the plate interior. One to plate processes such as sediment and water loading, flexure and thermal contraction and uplift fromProject EARTH-11-ABW1: Plate flexure, dynamic topography and global changes in sea-level Supervisor

  16. Global Control of Motor Neuron Topography Mediated by the Repressive Actions of a Single Hox Gene

    E-print Network

    Gifford, David K.

    Global Control of Motor Neuron Topography Mediated by the Repressive Actions of a Single Hox Gene transcription factors are critical in controlling motor neuron fates along the rostrocaudal axis, exemplified motor neuron diversity is constrained to limb-levels are however not well understood. We show

  17. A stress interpretation scheme applied to lunar gravity and topography data

    E-print Network

    A stress interpretation scheme applied to lunar gravity and topography data F. Chambat1 and B to be directly related to the deviatoric stresses without any rheological assumptions. In this approach a new set above the corresponding equipotential surfaces and (2) the stress difference. The method is applied

  18. Recent advances on the discontinuous Galerkin method for shallow water equations with topography source terms

    E-print Network

    Paris-Sud XI, Université de

    Recent advances on the discontinuous Galerkin method for shallow water equations with topography). Discontinuous Galerkin (DG in the following) methods have raised great interest during the past twenty years, 2014 Abstract We consider in this work the discontinuous Galerkin discretization of the nonlinear

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

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

  20. CMB topography and electrical conductivity as additional constraints for the lowermost mantle thermo-chemical structure

    NASA Astrophysics Data System (ADS)

    Deschamps, F.; Yin, Y.; Tackley, P. J.

    2013-12-01

    A variety of seismic observations, including tomographic models, indicate that the lowermost mantle is strongly heterogeneous. Seismic observations further support a thermo-chemical origin for the large scale heterogeneities. In particular, the large low-shear wave velocity provinces (LLSVP) observed by global tomographic images are better explained by a combination of thermal and chemical anomalies. Despite the accuracy of seismic information, uncertainties and trade-off still prevent the determination of a detailed lower mantle thermo-chemical structure. For instance, the nature of chemical heterogeneities and the exact role played by the post-perovskite phase transition are still debated. Additional constraints are needed to discriminate between the possible models of structure and dynamics of the lower mantle. Here, we consider two potential additional constraints, the electrical conductivity and the dynamic topography at the core-mantle boundary (CMB). Unlike density and seismic velocities, electrical conductivity increases with temperature. In addition, it strongly varies with the iron and silicate content. Using appropriate mineral physics data, we calculated a 3D distribution of electrical conductivity in lower mantle from the thermo-chemical structure inferred by probabilistic tomography, which maps iron and silicate excess in the LLSVP. In the lowermost mantle, we observe a belt of high conductivity, with maximum values around 20 S/m located in the LLSVP. Such a belt may trigger electric currents in the lowermost mantle and induce magnetic field variations with period of one year or more. It may thus be seen by global models of electrical conductivity. Unfortunately, such models do not sample yet regions deeper than 2000 km. A second, independent constraint we explored is the dynamic topography at the CMB. We used stagYY to calculate the dynamic topography associated with several models of thermo-chemical convection, and observe strong differences depending on the model. In models that include large thermo-chemical reservoirs, corresponding to the LLSVP seen by seismic tomography, the CMB dynamic topography is dominated by ridges about 5 km high along the borders of the reservoirs. The spherical harmonic power spectra is dominated by degrees 8 to 10. By contrast, in isochemical models, the dynamic topography focuses at the foot of plumes, where it reaches about 20 km, and is dominated by low (2 and 3) spherical harmonic degrees. Again, the CMB topography may have some implications for the dynamics of the outer core, and the details of the magnetic field. Further developments in seismology may also give a better image of the CMB topography.