Sample records for crescent dunes solar

  1. Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03634 Dunes

    This dune field is located on the floor of a crater located southeast of Mutch Crater.

    Image information: VIS instrument. Latitude 3.1S, Longitude 307.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  2. Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03079 Dunes

    These dunes are located on the floor of an unnamed crater SE of Campbell Crater.

    Image information: VIS instrument. Latitude 57.3S, Longitude 168.7E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  3. Barchan Dunes

    NASA Technical Reports Server (NTRS)

    2004-01-01

    28 April 2004 One of the simplest forms a sand dune can take is the barchan. The term, apparently, comes from the Arabic word for crescent-shaped dunes. They form in areas with a single dominant wind direction that are also not overly-abundant in sand. The barchan dunes shown here were imaged in March 2004 by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) as it passed over a crater in western Arabia Terra near 21.1oN, 17.6oW. The horns and steep slope on each dune, known as the slip face, point toward the south, indicating prevailing winds from the north (top). The picture covers an area about 3 km (1.9 mi) across and is illuminated by sunlight from the lower left.

  4. Lunar crescent visibility

    NASA Technical Reports Server (NTRS)

    Doggett, Leroy E.; Schaefer, Bradley E.

    1994-01-01

    We report the results of five Moonwatches, in which more than 2000 observers throughout North America attempted to sight the thin lunar crescent. For each Moonwatch we were able to determine the position of the Lunar Date Line (LDL), the line along which a normal observer has a 50% probability of spotting the Moon. The observational LDLs were then compared with predicted LDLs derived from crescent visibility prediction algorithms. We find that ancient and medieval rules are higly unreliable. More recent empirical criteria, based on the relative altitude and azimuth of the Moon at the time of sunset, have a reasonable accuracy, with the best specific formulation being due to Yallop. The modern theoretical model by Schaefer (based on the physiology of the human eye and the local observing conditions) is found to have the least systematic error, the least average error, and the least maximum error of all models tested. Analysis of the observations also provided information about atmospheric, optical and human factors that affect the observations. We show that observational lunar calendars have a natural bias to begin early.

  5. Predicting the effect of changing vegetation conditions on aeolian dune landscapes

    Microsoft Academic Search

    M. D. Reitz; D. J. Jerolmack; R. C. Ewing; R. L. Martin

    2010-01-01

    One system in which climate change can directly alter a landscape through the medium of plant life is that of aeolian dunes. Under the influence of vegetation, barchan dunes invert their crescents and turn into stabilized parabolic dunes. Whether local vegetation succeeds in effecting this transition depends on the relative strengths of dune surface erosion\\/deposition rates, which impede plant growth

  6. Relapsing polychondritis with crescentic glomerulonephritis

    Microsoft Academic Search

    G H Neild; J S Cameron; M H Lessof; C S Ogg; D R Turner

    1978-01-01

    Relapsing polychondritis is rare and its cause is unknown. The tissues affected are those with a high glycosaminoglycan content, such as cartilage, the aorta, the sclera and cornea, and parts of the ear. Symptoms can usually be controlled with oral steroids, but when there is coexistent progressive crescentic glomerulonephritis quadruple chemotherapy may be used. Three cases of the clinical syndrome

  7. Terrestrial analogs of the Hellespontus dunes, Mars

    NASA Technical Reports Server (NTRS)

    Breed, C. S.

    1977-01-01

    Geomorphic features in the Hellespontus region, Mars, were compared with dunes of the crescentic ridge type in numerous terrestrial sand seas quantitatively by dimensional analysis of dune lengths, widths, and wavelengths. Mean values for the Hellespontus dunes are close to mean values derived from measurements of all sampled terrestrial sand seas. Terrestrial analogs of form and areal distribution of the Hellespontus dunes are shown by comparison of scale ratios derived from the measurements. Dunes of similar form occur in South West Africa, in Pakistan, in the southeastern Arabian peninsula, in the Sahara, in eastern USSR and northern China, and in western North America. Terrestrial analogs closest to form and areal distribution of the Hellespontus dunes are in the Kara Kum Desert, Turkmen SSR, and in the Ala Shan (Gobi) Desert, China.

  8. Eolian dunes: Computer simulations and attractor interpretation

    Microsoft Academic Search

    B. T. Werner

    1995-01-01

    A simple computer-simulation algorithm for the transport of sand by wind produces forms resembling barchan, crescentic ridge, linear, and star natural dune classes. Sand is moved as slabs composed of many grains that are picked up at random, transported in a specified direction, and deposited (1) with a probability that depends on the local presence or absence of sand or

  9. Crescent Singularities in Crumpled Sheets

    NASA Astrophysics Data System (ADS)

    Liang, Tao; Witten, Thomas

    2004-03-01

    We examine the crescent singularity of a developable cone in a setting similar to that studied by Cerda et al [1]. Stretching is localized in a core region near the pushing tip and bending dominates the outer region. Two types of strains in the outer region are identified and shown to scale differently with the distance to the tip. The cone's confining ring affects the local curvature dramatically. The radial curvature shows a sharp maximum as one crosses the ring. Its magnitude is sufficient to render the mean curvature nearly zero at the ring. Test of the pushing force equation and direct geometrical measurements provide numerical evidence that core region size Rc scales as Rc ˜ h^1/3 R^2/3, where h is the thickness of the sheet and R is the supporting container radius, in agreement with the arguments of Ref. [1]. For crescent singularity produced in a setting without supporting container, our numerics suggest a different scaling law: Rc ˜ h. [1] ``Conical dislocations in crumpling'' by E. Cerda, S. Chaieb, F. Melo, L. Mahadevan, Nature, Vol. 401, p. 46 (1999).

  10. Crescent Singularities in Crumpled Sheets

    E-print Network

    Tao Liang; Thomas A. Witten

    2004-12-05

    We examine the crescent singularity of a developable cone in a setting similar to that studied by Cerda et al [Nature 401, 46 (1999)]. Stretching is localized in a core region near the pushing tip and bending dominates the outer region. Two types of stresses in the outer region are identified and shown to scale differently with the distance to the tip. Energies of the d-cone are estimated and the conditions for the scaling of core region size R_c are discussed. Tests of the pushing force equation and direct geometrical measurements provide numerical evidence that core size scales as R_c ~ h^{1/3} R^{2/3}, where h is the thickness of sheet and R is the supporting container radius, in agreement with the proposition of Cerda et al. We give arguments that this observed scaling law should not represent the asymptotic behavior. Other properties are also studied and tested numerically, consistent with our analysis.

  11. Crescent singularities in crumpled sheets

    NASA Astrophysics Data System (ADS)

    Liang, Tao; Witten, Thomas A.

    2005-01-01

    We examine the crescent singularity of a developable cone in a setting similar to that studied by Cerda , [Nature (London) 401, 46 (1999)]. Stretching is localized in a core region near the pushing tip and bending dominates the outer region. Two types of stresses in the outer region are identified and shown to scale differently with the distance to the tip. Energies of the d cone are estimated and the conditions for the scaling of core region size Rc are discussed. Tests of the pushing force equation and direct geometrical measurements provide numerical evidence that core size scales as Rc˜h1/3R2/3 , where h is the thickness of sheet and R is the supporting container radius, in agreement with the proposition of Cerda We give arguments that this observed scaling law should not represent the asymptotic behavior. Other properties are also studied and tested numerically, consistent with our analysis.

  12. 77 FR 39413 - Safety Zone: Crescent City Fourth of July Fireworks Event, Crescent City, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-07-03

    ...sponsor the Crescent City Fourth of July Fireworks Event...for the Crescent City Fourth of July Fireworks Event...either preempt State law or impose a substantial...Homeland Security Management Directive 023-01 and Commandant...zone; Crescent City Fourth of July Fireworks...

  13. Numerical Investigation of Isolated Crescent Singularity

    E-print Network

    Tao Liang

    2008-04-25

    In this paper we examine numerically the properties, especially the scaling properties, of an isolated crescent singularity similar to that of a developable cone. The desired isolated crescent region is produced by applying six potential forces to an elastic sheet in a controlled way, for which no central pushing force is required. Two types of length scales of the crescent are identified and shown to scale differently with the thickness and the separation of potentials. It is found that in one direction, the width of the crescent scales with both thickness and separation to the 1/2 power. In the other direction, the radius of curvature of the crescent scales with thickness to the 1/3 power and separation to the 2/3 power, in agreement with previous observation for the crescent size of a developable cone. We expect our findings of the double features of the crescent singularity to have importance in understanding the puzzling scaling behavior of the crescent.

  14. Dune morphodynamics

    NASA Astrophysics Data System (ADS)

    Courrech du Pont, Sylvain

    2015-01-01

    The physics of dunes relies on the interaction between a wind flow and an erodible topography. Thus, if strong enough to transport grains, the wind shapes sandy areas into dune fields. These dunes are reminiscent of a wavy sea so that sandy deserts are called sand seas. However, the comparison stops there. Contrary to water waves, dunes propagate only under wind action and when the wind stops, they do not vanish but stand. Consequently, dunes are not only the result of the present winds, but can integrate the wind regimes over long periods. Thus, they exhibit a range of shapes and sizes with superimposed patterns. They are witnesses of past wind regimes and their shape and orientation are used to constraint climatic models on other planetary bodies where they are observed as well (e.g., Mars, Titan and Venus). Here, we discuss the morphodynamics of dunes and endeavor to identify and to explain the physical mechanisms at play in the selection of their shape, size and orientation, whilst focusing on Earth desert sand dunes.

  15. VIEW OF HOWLAND HILL ROAD, JEDEDIAH SMITH STATE PARK. CRESCENT ...

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

    VIEW OF HOWLAND HILL ROAD, JEDEDIAH SMITH STATE PARK. CRESCENT CITY, DEL NORTE COUNTY, CALIFORNIA. LOOKING E. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA

  16. VIEW OF HOWLAND HILL ROAD, JEDEDIAH SMITH STATE PARK. CRESCENT ...

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

    VIEW OF HOWLAND HILL ROAD, JEDEDIAH SMITH STATE PARK. CRESCENT CITY, DEL NORTE COUNTY, CALIFORNIA. LOOKING W. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA

  17. VIEW OF HOWLAND HILL ROAD, JEDEDIAH SMITH STATE PARK. CRESCENT ...

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

    VIEW OF HOWLAND HILL ROAD, JEDEDIAH SMITH STATE PARK. CRESCENT CITY, DEL NORTH COUNTY, CALIFORNIA. LOOKING ESE. - Redwood National & State Parks Roads, California coast from Crescent City to Trinidad, Crescent City, Del Norte County, CA

  18. Dune Variety

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Our topic for the weeks of April 4 and April 11 is dunes on Mars. We will look at the north polar sand sea and at isolated dune fields at lower latitudes. Sand seas on Earth are often called 'ergs,' an Arabic name for dune field. A sand sea differs from a dune field in two ways: 1) a sand sea has a large regional extent, and 2) the individual dunes are large in size and complex in form.

    Our final look at the north polar erg was taken at 80 degrees North latitude during Northern summer. This image is of lower resolution than the previous images, but covers a much larger area. The dunes have very little remaining frost cover. Note the large extent of coverage, and the different dune forms.

    Image information: VIS instrument. Latitude 80.8, Longitude 184.6 East (175.4 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  19. Spotty Dunes

    NASA Technical Reports Server (NTRS)

    2004-01-01

    27 July 2004 Frost-covered dunes develop spots and streaks as they begin to defrost in springtime. This April 2004 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of north polar dunes in the early stages of the defrosting process. At the time the image was acquired, Mars was only 1 month into the northern spring season. The picture is located near 75.9oN, 266.0oW, and is illuminated by sunlight from the lower left. The image covers an area about 3 km (1.9 mi) wide.

  20. Dune Variety

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02173 Dune Variety

    This image of the east end of Coprates Chasma contains several dune fields. The dunes in the center of the image are larger and darker than the dunes at the bottom.

    Image information: VIS instrument. Latitude -14.8N, Longitude 304.3E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  1. Rippled Dune

    NASA Technical Reports Server (NTRS)

    2004-01-01

    10 October 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows ripples on the surface of a dune in a crater west of Sinus Meridiani near 2.5oN, 9.3oW. Most martian dune surfaces do not show ripples at the scale of MOC images---a higher resolution (better than 15 cm/pixel) view would be needed. These ripples are probably not typical sand ripples; they may be coarser-grained granule ripples (usually made up, in part, of grains 1-4 millimeters in size). The light-toned features in the image are wind-eroded outcrops of sedimentary rock. The image covers an area about 1.5 km (0.9 mi) wide. Sunlight illuminates the scene from the upper left.

  2. DuneXpress

    NASA Astrophysics Data System (ADS)

    Grün, Eberhard; Srama, Ralf; Altobelli, Nicolas; Altwegg, Kathrin; Carpenter, James; Colangeli, Luigi; Glassmeier, Karl-Heinz; Helfert, Stefan; Henkel, Hartmut; Horanyi, Mihaly; Jäckel, Annette; Kempf, Sascha; Landgraf, Markus; McBride, Neil; Moragas-Klostermeyer, Georg; Palumbo, Pasquale; Scholten, Han; Srowig, Andre; Sternovsky, Zoltan; Vo, Xavier

    2009-03-01

    The DuneXpress observatory will characterize interstellar and interplanetary dust in-situ, in order to provide crucial information not achievable with remote sensing astronomical methods. Galactic interstellar dust constitutes the solid phase of matter from which stars and planetary systems form. Interplanetary dust, from comets and asteroids, represents remnant material from bodies at different stages of early solar system evolution. Thus, studies of interstellar and interplanetary dust with DuneXpress in Earth orbit will provide a comparison between the composition of the interstellar medium and primitive planetary objects. Hence DuneXpress will provide insights into the physical conditions during planetary system formation. This comparison of interstellar and interplanetary dust addresses directly themes of highest priority in astrophysics and solar system science, which are described in ESA’s Cosmic Vision. The discoveries of interstellar dust in the outer and inner solar system during the last decade suggest an innovative approach to the characterization of cosmic dust. DuneXpress establishes the next logical step beyond NASA’s Stardust mission, with four major advancements in cosmic dust research: (1) analysis of the elemental and isotopic composition of individual interstellar grains passing through the solar system, (2) determination of the size distribution of interstellar dust at 1 AU from 10 - 14 to 10 - 9 g, (3) characterization of the interstellar dust flow through the planetary system, (4) establish the interrelation of interplanetary dust with comets and asteroids. Additionally, in supporting the dust science objectives, DuneXpress will characterize dust charging in the solar wind and in the Earth’s magnetotail. The science payload consists of two dust telescopes of a total of 0.1 m2 sensitive area, three dust cameras totaling 0.4 m2 sensitive area, and a nano-dust detector. The dust telescopes measure high-resolution mass spectra of both positive and negative ions released upon impact of dust particles. The dust cameras employ different detection methods and are optimized for (1) large area impact detection and trajectory analysis of submicron sized and larger dust grains, (2) the determination of physical properties, such as flux, mass, speed, and electrical charge. A nano-dust detector searches for nanometer-sized dust particles in interplanetary space. A plasma monitor supports the dust charge measurements, thereby, providing additional information on the dust particles. About 1,000 grains are expected to be recorded by this payload every year, with 20% of these grains providing elemental composition. During the mission submicron to micron-sized interstellar grains are expected to be recorded in statistically significant numbers. DuneXpress will open a new window to dusty universe that will provide unprecedented information on cosmic dust and on the objects from which it is derived.

  3. Crater Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03580 Crater Dunes

    Individual dunes are found on the floor of this unnamed crater located to the north of Rabe Crater.

    Image information: VIS instrument. Latitude 41.1S, Longitude 34,4E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  4. 5. APPROACH VIEW FROM CRESCENT CITY (SOUTH) END OF BRIDGE, ...

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

    5. APPROACH VIEW FROM CRESCENT CITY (SOUTH) END OF BRIDGE, LOOKING SOUTHEAST. Emergency bracing under collapsed cantilever tower visible inside trusses. - Smith River Bridge, CA State Highway 199 Spanning Smith River, Crescent City, Del Norte County, CA

  5. International Federation of Red Cross and Red Crescent Societies

    MedlinePLUS

    ... Sitemap Go to top The International Federation of Red Cross and Red Crescent Societies (IFRC) is the world's largest humanitarian ... member National Societies . As part of the International Red Cross and Red Crescent Movement, our work is ...

  6. 33 CFR 80.1152 - Crescent City Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...2010-07-01 2010-07-01 false Crescent City Harbor, CA. 80.1152 Section 80.1152 Navigation and Navigable Waters...DEMARCATION LINES Pacific Coast § 80.1152 Crescent City Harbor, CA. A line drawn from Crescent City Entrance Light to the...

  7. 33 CFR 80.1152 - Crescent City Harbor, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...2011-07-01 2011-07-01 false Crescent City Harbor, CA. 80.1152 Section 80.1152 Navigation and Navigable Waters...DEMARCATION LINES Pacific Coast § 80.1152 Crescent City Harbor, CA. A line drawn from Crescent City Entrance Light to the...

  8. 'Endurance Crater's' Dazzling Dunes

    NASA Technical Reports Server (NTRS)

    2004-01-01

    As NASA's Mars Exploration Rover Opportunity creeps farther into 'Endurance Crater,' the dune field on the crater floor appears even more dramatic. This approximate true-color panoramic camera image highlights the reddish-colored dust present throughout the scene.

    Sinuous tendrils of sand less than 1 meter (3.3 feet) high extend from the main dune field toward the rover. Scientists hope to send the rover down to one of these tendrils in an effort to learn more about the characteristics of the dunes. Dunes are a common feature across the surface of Mars, and knowledge gleaned from investigating the Endurance dunes close-up may apply to similar dunes elsewhere.

    Before the rover heads down to the dunes, rover drivers must first establish whether the slippery slope that leads to them is firm enough to ensure a successful drive back out of the crater. Otherwise, such hazards might make the dune field a true sand trap.

  9. Color Voyager 2 Image Showing Crescent Uranus

    NASA Technical Reports Server (NTRS)

    1990-01-01

    This image shows a crescent Uranus, a view that Earthlings never witnessed until Voyager 2 flew near and then beyond Uranus on January 24, 1986. This planet's natural blue-green color is due to the absorption of redder wavelengths in the atmosphere by traces of methane gas. Uranus' diameter is 32,500 miles, a little over four times that of Earth. The hazy blue-green atmosphere probably extends to a depth of around 5,400 miles, where it rests above what is believed to be an icy or liquid mixture (an 'ocean') of water, ammonia, methane, and other volatiles, which in turn surrounds a rocky core perhaps a little smaller than Earth.

  10. Crescentic glomerulonephritis: new aspects of pathogenesis.

    PubMed

    Tarzi, Ruth M; Cook, H Terence; Pusey, Charles D

    2011-07-01

    This review provides a summary of recent advances in the understanding of crescentic glomerulonephritis, focusing on antineutrophil cytoplasm antibody (ANCA)-associated vasculitis and anti-glomerular basement membrane (anti-GBM) antibody disease. In ANCA-associated vasculitis (AAV), four main conceptual advances are discussed as follows: (1) evidence for the pathogenicity of ANCA, (2) molecular mimicry and the role of infection in AAV, (3) evidence for aberrant T-cell responses and T-cell regulation in AAV, and (4) advances in understanding of genetic predisposition to AAV. In relation to anti-GBM disease we discuss the following: (1) the nature of the Goodpasture autoantigens, (2) T-cell responses and regulation in anti-GBM disease, and (3) human leukocyte antigen and non-human leukocyte antigen genetic associations. PMID:21839369

  11. The vanishing wheat landraces of the Fertile Crescent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Genetic diversity of wheat landraces constituted a sizable portion of the mega diversity in the Fertile Crescent as a center of origin and of diversity of major crop plants. Following wheat domestication in the Fertile Crescent, early farmers developed diverse wheat landraces, and contributed to the...

  12. The role of vegetation in shaping dune morphology

    NASA Astrophysics Data System (ADS)

    Duran Vinent, O.; Moore, L. J.; Young, D.

    2012-12-01

    Aeolian dunes naturally emerge under strong winds and sufficient sand supply. They represent the most dynamical feature of the arid and/or coastal landscape and their evolution has the potential to either increase desertification or reduce coastal vulnerability to storms. Although large-scale dune morphology mainly depends on the wind regime and sand availability, vegetation plays an important role in semiarid and/or coastal areas. It is well known that under certain conditions vegetation is able to stabilize dunes, driving a morphological transformation from un-vegetated mobile crescent dunes to static vegetated "parabolic" dunes, de facto paralyzing desertification and initiating land recovery. Furthermore, vegetation is also the primary ingredient in the formation of coastal foredunes, which determine vulnerability to storms, as low dunes are prone to storm-induced erosion and overwash. In both cases, the coupling of biological and geomorphic (physical) processes, in particular vegetation growth and sand transport, governs the evolution of morphology. These processes were implemented in a computational model as part of a previous effort. It was shown that, for a migrating dune, this coupling leads to a negative feedback for dune motion, where an ever denser vegetation implies ever lesser sand transport. The model also predicted the existence of a "mobility index", defined by the vegetation growth rate to sand erosion rate ratio, that fully characterizes the morphological outcome: for indices above a certain threshold biological processes are dominant and dune motion slows after being covered by plants; for lower indices, the physical processes are the dominant ones and the dune remains mobile while vegetation is buried or rooted out. Here, we extend this model to better understand the formation of coastal dunes. We include new physical elements such as the shoreline and water table, as well as different grass species and potential competition among them. Consistent with field observations, we find that basic dune morphology is primarily determined by grass species, with linear or hummocky dunes being built by some species, while others may prevent dune formation. We also find that the evolution of coastal dune morphology is controlled by at least two bio-geomorphic couplings: (1) between vegetation growth and sand transport, which leads to a positive feedback for dune growth, as certain beach grasses maximize growth under sand accretion, which means that an ever denser vegetation implies an ever higher accretion rate; and (2) between vegetation growth and shoreline position through the sand influx. While the first coupling is responsible for dune formation, the second one determines when dunes stop growing and thus controls final dune size. This is particularly relevant for accreting/eroding coastlines where we find that dune size, and thus coastal protection, is maximized for relatively small accretion rates while larger accretion rates lead to formation of a new, smaller dune ridge at the beach.

  13. Unchanging Desert Sand Dunes

    NASA Astrophysics Data System (ADS)

    Gadhiraju, S.; Banerjee, B.; Buddhiraju, K.; Shah, V.

    2013-12-01

    Deserts are one of the major landforms on earth. They occupy nearly 20% of the total land area but are relatively less studied. With the rise in human population, desert regions are being gradually occupied for settlement posing a management challenge to the concerned authorities. Unrestrained erosion is generally a feature of bare dunes. Stabilized dunes, on the other hand, do not undergo major changes in textures, and can thus facilitate the growth of vegetation. Keeping in view of the above factors, better mapping and monitoring of deserts and particularly of sand dunes is needed. Mapping dunes using field instruments is very arduous and they generate relatively sparse data. In this communication, we present a method of clustering and monitoring sand dunes through imagery captured by remote sensing sensors. Initially Radon spectrum of an area is obtained by decomposition of the image into various projections sampled at finer angular directions. Statistical features such as mode, entropy and standard deviation of Radon spectrum are used in delineation and clustering of regions with different dune orientations. These clustered boundaries are used to detect if there are any changes occurring in the dune regions. In the experiment's, remote sensing data covering various dune regions of the world are observed for possible changes in dune orientations. In all the cases, it is seen that there are no major changes in desert dune orientations. While these findings have implications for understanding of dune geomorphology and changes occurring in dune directions, they also highlight the importance of a wider study of dunes and their evolution both at regional and global scales. Results for Dataset 1 & Dataset 2 Results for Dataset 3

  14. Rapidly progressive crescentic glomerulonephritis: Early treatment is a must.

    PubMed

    Moroni, Gabriella; Ponticelli, Claudio

    2014-07-01

    The term crescentic glomerulonephritis (GN) refers to a pathologic condition characterized by extracapillary proliferation in >50% of glomeruli. Clinically crescentic GN is characterized by a nephritic syndrome rapidly progressing to end stage renal disease (ESRD). Three types of crescentic GN have been identified. Type 1 includes cases of Goodpasture syndrome characterized by linear deposits of antibodies along the glomerular basement membrane (GBM) at immunofluorescence. Type 2 is a heterogeneous group of primary or secondary glomerular diseases complicated by crescentic GN. In this category there are granular deposits of immunoglobulins and complement fractions on the glomerular tuft. Type 3 includes cases of ANCA-associated small-vessel vasculitis. Immunofluorescence is negative or may show only faint deposits of immunoglobulins. The etiology and the initial pathogenetic factors are different in the three types, but the final mechanisms leading to crescent formation and the renal symptoms and signs are similar. The prognosis depends on the timeline of diagnosis and treatment. Although some patients requiring dialysis may recover a good renal function, usually the higher the serum creatinine at presentation the worse the outcome. When treatment is initiated early, most patients obtain a complete or partial remission. High-dose corticosteroids and cyclophosphamide represent the standard therapy for crescentic GN. The addition of plasma exchange may also be helpful, particularly in patients with massive alveolar hemorrhage. Anti-B monoclonal antibodies have also been used in some patients with crescentic GN, but their role in this particular area is still poorly established. PMID:24657897

  15. Can a Crescent Mars Ever Be Seen from Earth?

    ERIC Educational Resources Information Center

    Lamb, John F., Jr.

    1990-01-01

    Described is an activity that incorporates a computer, geometry, algebra, trigonometry, and calculus to answer questions about the planet Mars. A possible crescent of Mars is compared to those of Venus and Mercury. (KR)

  16. Windblown Dunes on the Floor of Herschel Impact Basin

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Herschel Basin, one of many meteor impact craters on Mars, has some dark material on its floor that appeared from earlier spacecraft missions to have been blown and/or deposited by wind. Herschel Basin was imaged at low resolution by the Mariner 9 and Viking orbiters ((A) above) in the 1970s, and again by the Phobos 2 orbiter in 1989.

    On June 14, 1998, Mars Global Surveyor's Mars Orbiter Camera revealed that part of the dark surface on the floor of Herschel Basin consists of a field of sand dunes ((B) above). These dunes have a distinct crescent-like shape characteristic of dunes on Earth called barchan dunes. They result from winds that blow from a single dominant direction.

    In the case of Herschel Basin, the dunes indicate that the strongest winds blow approximately north-to-south. The crescent horns on the ends of some of the dunes in this image are elongated. This condition indicates that the dominant winds do not always blow in exactly the same direction-- sometimes the winds blow from the northeast, sometimes from the northwest, and sometimes from the north. The local topography probably influences the wind direction--and hence dune shape--because this dune field is located on a narrow, low plain between a high crater rim to the east, and a narrow mountain range-- the inner ring of the Herschel impact basin--to the west (see image (A)).

    MOC image 36507 was obtained on Mars Global Surveyor's 365th orbit around 10:51 a.m. PDT on June 14, 1998. This subframe is centered around 14.27oS, 231.68oW.

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  17. Coastal dunes: sensitive or not?

    Microsoft Academic Search

    Izak C. Rust; Werner K. Illenberger

    1996-01-01

    This paper introduces a classification of coastal dune systems into two main morphodynamic classes, namely retentive and transgressive dune systems. Retentive systems include coastal dune types where sand accumulation within vegetation is dominant over other processes. In this category we include such morphological types as hummock dunes, foredunes, and retention ridges, including sub-environments such as precipitation ridges that form the

  18. Stokes Crater Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    6 May 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows dark-toned sand dunes on the floor of Stokes Crater, located on the martian northern plains. The steepest slopes on the dunes indicate the direction of sand transport; the winds responsible for these dunes generally blow from the north/northeast (top/upper right).

    Location near: 55.9oN, 188.6oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Summer

  19. Dune Avalanche Scars

    NASA Technical Reports Server (NTRS)

    2004-01-01

    05 August 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows large, low albedo (dark) sand dunes in Kaiser Crater near 47.2oS, 340.4oW. The dunes are--ever so slowly--moving east to west (right to left) as sand avalanches down the steeper, slip face slopes of each. Avalanching sand in the Kaiser dune field has left deep scars on these slopes, suggesting that the sand is not loose but is instead weakly cemented. The image covers an area approximately 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.

  20. Impacts of Vegetation and Development on the Morphology of Coastal Sand Dunes Using Modern Geospatial Techniques: Jockey's Ridge Case Study

    NASA Astrophysics Data System (ADS)

    Weaver, K.; Mitasova, H.; Overton, M.

    2011-12-01

    LiDAR surveys acquired in the years 2007 and 2008, combined with previous LiDAR, topographic mapping and aerial imagery collected along the Outer Banks of North Carolina were used for comprehensive geospatial analysis of the largest sand dune on the eastern coast of the United States, Jockey's Ridge. The objective of the analysis was to evaluate whether the dune's evolution has continued as hypothesized in previous studies and whether an increase of development and vegetation has contributed to the dune's stabilization and overall loss of dune height. Geospatial analysis of the dune system evolution (1974 - 2008) was performed using time series of digital elevation models at one meter resolution. Image processing was conducted in order to analyze land cover change (1932 - 2009) using unsupervised classification to extract vegetation, development and sand in and around Jockey's Ridge State Park. The dune system evolution was then characterized using feature-based and raster-based metrics, including vertical and horizontal change of dune peaks, horizontal migration of dune crests, slip face geometry transformation and volume change analysis using the core and dynamic layer concept. Based on the evolutionary data studied, the volume of sand at Jockey's Ridge is consistent throughout time, composed of a stable core and a dynamically migrating layer that is not gaining or losing sand. Although the peak elevation of the Main Dune has decreased from 43m in 1953 to 22m in 2008, the analysis has shown that the sand is redistributed within the dune field. Today, the dune field peaks are increasing in elevation, and all of the dunes within the system are stabilizing at similar heights of 20-22m along with transformation of the dunes from unvegetated, crescentic to vegetated, parabolic dunes. The overall land cover trend indicates that since the 1930s vegetation and development have gradually increased over time, influencing the morphology of the dune field by stabilizing the area of sand that once fed the dunes, limiting aeolian sand transport and migration of the dune system. Not only are vegetation and development increasing around the Jockey's Ridge State Park, but vegetation is increasing inside the park boundaries with the majority of growth along the windward side of the dune system, blocking sand from feeding the dunes. Vegetation growth is also found to increase in front of the dune field, recently causing the migration of the dune to slow down.

  1. Isolated Northern Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Our topic for the weeks of April 4 and April 11 is dunes on Mars. We will look at the north polar sand sea and at isolated dune fields at lower latitudes. Sand seas on Earth are often called 'ergs,' an Arabic name for dune field. A sand sea differs from a dune field in two ways: 1) a sand sea has a large regional extent, and 2) the individual dunes are large in size and complex in form.

    This VIS image was taken at 81 degrees North latitude during Northern spring. In this region, the dunes are isolated from each other. The dunes are just starting to emerge from the winter frost covering appearing dark with bright crests. These dunes are located on top of ice.

    Image information: VIS instrument. Latitude 82.1, Longitude 191.3 East (168.7 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  2. Spring Time View of North Polar Sand Dunes

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Spring has come to the martian northern hemisphere. The northern spring season began in mid-July 1998. With the arrival of spring comes the annual shrinkage of the north polar frost cap. Sunlight is now falling on the north polar cap, and all of the carbon dioxide frost and snow that accumulated during winter has been sublimating--going directly from solid to gas--and the surface beneath the frost is being revealed.

    The MOC image shown above, 45205, was obtained during the 452nd orbit of Mars Global Surveyor at 3:10 p.m. PDT on July 26, 1998. The image is located near latitude 76.87oN, longitude 253.81oW, and it shows a close-up view of martian sand dunes. These dunes were not visible to MOC until the last week of July. Just a few months earlier, the dunes were likely covered with frost, obscured by thick clouds, and cloaked by the darkness of the martian polar winter. Indeed, small patches of bright frost were still present when the picture was taken (e.g., the bright patches on the west (left) side of each crescentic dune in (left image).

    As the above picture illustrates, the camera on board Mars Global Surveyor (MOC) continued to take exciting new views of the martian surface throughout July 1998. As the month progressed, the ground track-- the area visible to the camera--migrated farther north. Simultaneously, sunlight began falling on the north polar regions, making it possible to take some pictures at far northern latitudes. However, these regions have been tricky to photograph because of thick clouds and hazes. The image shown here, for example, is relatively bland gray (has relatively low contrast) because of clouds.

    As first seen by the Viking 2 Orbiter in 1976, a vast 'sea' of sand dunes surrounds the north polar cap. The dunes imaged by MOC (above) are classic forms known as barchan dunes--the small, crescent-shaped hills (see left image above)-- and transverse dunes--ridges that resemble coalesced barchans (shown in right image above). These dunes are similar in size and shape to familiar sand dunes found in desert regions on Earth. These two varieties form from winds that persistently come from a single direction (in this case, from the southwest).

    Over the next several months, the sky above these dunes will clear. Northern Summer will arrive near the end of January 1999, and Mars Global Surveyor should have an excellent view of this region when it begins its mapping mission in late March 1999. Because it is in a polar orbit, Mars Global Surveyor will have many opportunities to revisit the north polar dunes in 1999. The images in 1999 will have resolutions around 1.5 meters (5 feet) per pixel--a substantial improvement even over the pictures shown here.

  3. Crater Floor Dune Field

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Our topic for the weeks of April 4 and April 11 is dunes on Mars. We will look at the north polar sand sea and at isolated dune fields at lower latitudes. Sand seas on Earth are often called 'ergs,' an Arabic name for dune field. A sand sea differs from a dune field in two ways: 1) a sand sea has a large regional extent, and 2) the individual dunes are large in size and complex in form.

    Our final dune image shows a small dune field inside an unnamed crater south of Nili Fossae.

    Image information: VIS instrument. Latitude 20.6, Longitude 79 East (281 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  4. Holden Crater Dune Field

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Our topic for the weeks of April 4 and April 11 is dunes on Mars. We will look at the north polar sand sea and at isolated dune fields at lower latitudes. Sand seas on Earth are often called 'ergs,' an Arabic name for dune field. A sand sea differs from a dune field in two ways: 1) a sand sea has a large regional extent, and 2) the individual dunes are large in size and complex in form.

    A common location for dune fields on Mars is in the basin of large craters. This dune field is located in Holden Crater at 25 degrees South atitude.

    Image information: VIS instrument. Latitude -25.5, Longitude 326.8 East (33.2 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  5. Virulence of Hessian Fly (Diptera: Cecidomyiidae) in the Fertile Crescent

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Hessian fly, Mayetiola destructor (Say), is an important insect pest of wheat (Triticum spp.) in North Africa, North America, South Europe and North Kazakhstan. Similarly to wheat this pest is believed to originate from West Asia in the Fertile Crescent. To determine the virulence of the Hessian...

  6. [A systematic analysis of the Ottoman Red Crescent periodical].

    PubMed

    Okutan, Y

    2000-01-01

    Founded in 1877, the Ottoman Red Crescent Society rendered a lot of important services in military and civil areas in the Ottoman Empire. The Ottoman Red Crescent Society not only gave health services for the soldiers, but it also attempted to obey the international acts signed for the war captives and to rescue them together with the countries involved under the supervision of the international Red Cross. In the civilian area, the Ottoman Red Crescent Society also played an active role to meet the casualties' needs, such as food, clothes, and accommodation following natural disasters like earthquake, flood, fire etc. The Ottoman Red Crescent Society published a monthly newsletter called Osmanli Hilâl-i Ahmer Mecmuasi to announce its services more effectively to the public since 15 September 1921 (12 Muharrem 1346). The publication of the newsletter continued as Türkiye Hilâl-i Ahmer Mecmuasi after the 15th issue. Starting with the 85th issue on September 15th, 1928 (30 Rebiülevvel 1347) it was printed with Latin alphabet instead of Arabic letters.A brief translation in French and in English exist in the end of each issue. PMID:15053014

  7. Nili Patera Dune Field

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Our topic for the weeks of April 4 and April 11 is dunes on Mars. We will look at the north polar sand sea and at isolated dune fields at lower latitudes. Sand seas on Earth are often called 'ergs,' an Arabic name for dune field. A sand sea differs from a dune field in two ways: 1) a sand sea has a large regional extent, and 2) the individual dunes are large in size and complex in form.

    This VIS image shows a dune field within Nili Patera, the northern caldera of a large volcanic complex in Syrtis Major.

    Image information: VIS instrument. Latitude 9, Longitude 67 East (293 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  8. Minimal Model for Sand Dunes

    E-print Network

    Klaus Kroy; Gerd Sauermann; Hans J. Herrmann

    2002-03-02

    We propose a minimal model for aeolian sand dunes. It combines an analytical description of the turbulent wind velocity field above the dune with a continuum saltation model that allows for saturation transients in the sand flux. The model provides a qualitative understanding of important features of real dunes, such as their longitudinal shape and aspect ratio, the formation of a slip face, the breaking of scale invariance, and the existence of a minimum dune size.

  9. Polar Dunes, Spotted

    NASA Technical Reports Server (NTRS)

    2004-01-01

    23 August 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows sand dunes in the martian north polar region in mid-spring, July 2004. In summer, the dunes will be dark. As they defrost, dark spots form on their surfaces. This image is located near 82.8oN, 219.6oW. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the lower left.

  10. Frosted Chasma Boreale Dunes

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-390, 13 June 2003

    This is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) view of frost-covered sand dunes in Chasma Boreale in the early northern spring season. Dark spots, some of them with bright halos of re-precipitated frost, have formed as the dunes begin to defrost. Most of the frost is carbon dioxide which freezes out of the atmosphere during the cold martian polar winters. This picture is located near 84.7oN, 358.8oW, and is illuminated from the lower left.

  11. Basaltic lava flows covering active aeolian dunes in the Paraná Basin in southern Brazil: Features and emplacement aspects

    NASA Astrophysics Data System (ADS)

    Waichel, Breno L.; Scherer, Claiton M. S.; Frank, Heinrich T.

    2008-03-01

    Burial of active aeolian dunes by lava flows can preserve the morphology of the dunes and generate diverse features related to interaction between unconsolidated sediments and lavas. In the study area, located in southern Brazil, burial of aeolian deposits by Cretaceous basaltic lava flows completely preserved dunes, and generate sand-deformation features, sand diapirs and peperite-like breccia. The preserved dunes are crescentic and linear at the main contact with basalts, and smaller crescentic where interlayered with lavas. The various feature types formed on sediment surfaces by the advance of the flows reflect the emplacement style of the lavas which are compound pahoehoe type. Four feature types can be recognized: (a) type 1 features are related to the advance of sheet flows in dune-interdune areas with slopes > 5°, (b) type 2 is formed where the lava flows advance in lobes and climb the stoss slope of crescentic dunes (slopes 8-12°), (c) type 3 is generated by toes that descend the face of linear dunes (slopes 17-23°) and (d) type 4 occurs when lava lobes descend the stoss slope of crescentic dunes (slopes 10-15°). The direction of the flows, the disposition and morphology of the dunes and the ground slope are the main factors controlling formation of the features. The injection of unconsolidated sand in lava lobes forms diapirs and peperite-like breccias. Sand diapirs occur at the basal portion of lobes where the lava was more solidified. Peperite-like breccias occur in the inner portion where lava was more plastic, favoring the mingling of the components. The generation of both features is related to a mechanical process: the weight of the lava causes the injection of sand into the lava and the warming of the air in the pores of the sand facilitates this process. The lava-sediment interaction features presented here are consistent with previous reports of basalt lavas with unconsolidated arid sediments, and additional new sand-deformation features formed by lava breakouts and sand diapir injections are presented.

  12. International Federation of Red Cross and Red Crescent Societies

    NSDL National Science Digital Library

    With a broad mission, the International Federation of Red Cross and Red Crescent Societies are involved in everything from disaster response and management to capacity building all over the globe. As one might expect, visitors to the site can learn about some of their more well-known programs in the "Get Involved" area on the homepage. Their homepage is also an excellent place to learn about some of their research publications, which include their annual "World Disasters Report" and their in-house magazine, "Red Cross, Red Crescent". For more nuts-and-bolts type information on the organization, visitors should browse through the "Who We Are", "What We Do", and "Where We Work" sections. Additionally, visitors can enter the "Our Programmes" section to learn about their various outreach efforts in different regions of the world.

  13. Membranous glomerulopathy with superimposed pauci-immune necrotizing crescentic glomerulonephritis

    PubMed Central

    Fatima, Huma; Siew, Edward D.; Dwyer, Jamie P.; Paueksakon, Paisit

    2012-01-01

    We describe a 61-year-old woman with acute kidney injury, nephrotic range proteinuria and hematuria. Kidney biopsy showed membranous glomerulopathy (MG) with superimposed pauci-immune necrotizing crescentic glomerulonephritis (PNCGN). Coexistent MG and PNCGN is a rare occurrence. The diagnosis of such an exceptionally rare combination relies on the combination of renal biopsy findings and serologic testing. We also review previous reported cases and discuss possible pathogenesis of this rare dual glomerulopathy.

  14. Experimental crescentic glomerulonephritis: a new bicongenic rat model.

    PubMed

    D'Souza, Zelpha; McAdoo, Stephen P; Smith, Jennifer; Pusey, Charles D; Cook, H Terence; Behmoaras, Jacques; Aitman, Timothy J

    2013-11-01

    Crescentic glomerulonephritis (CRGN) is a major cause of human kidney failure, but the underlying mechanisms are not fully understood. Wistar Kyoto (WKY) rats are uniquely susceptible to CRGN following injection of nephrotoxic serum, whereas Lewis (LEW) rats are resistant. Our previous genetic studies of nephrotoxic nephritis (NTN), a form of CRGN induced by nephrotoxic serum, identified Fcgr3 and Jund as WKY genes underlying the two strongest quantitative trait loci for NTN phenotypes: Crgn1 and Crgn2, respectively. We also showed that introgression of WKY Crgn1 or Crgn2 individually into a LEW background did not lead to the formation of glomerular crescents. We have now generated a bicongenic strain, LEW.WCrgn1,2, in which WKY Crgn1 and Crgn2 are both introgressed into the LEW genetic background. These rats show development of NTN phenotypes, including glomerular crescents. Furthermore, we characterised macrophage function and glomerular cytokine profiles in this new strain. Additionally, we show that LEW.WCrgn1,2 rats are resistant to the development of glomerular crescents that is usually induced following immunisation with recombinant rat ?3(IV)NC1, the specific Goodpasture autoantigen located in the glomerular basement membrane against which the immune response is directed in experimental autoimmune glomerulonephritis. Our results show that the new bicongenic strain responds differently to two distinct experimental triggers of CRGN. This is the first time that CRGN has been induced on a normally resistant rat genetic background and identifies the LEW.WCrgn1,2 strain as a new, potentially valuable model of macrophage-dependent glomerulonephritis. PMID:24046355

  15. A footprint study of bond initiation in gold wire crescent bonding

    Microsoft Academic Search

    Y. n. Zhou; X. Li; N. J. Noolu

    2005-01-01

    The morphological features of the crescent bond footprints on the substrate after peeling the wire off were studied to gain an understanding of the effect of process parameters on the crescent bond formation. In the absence of any ultrasonic energy, metallurgical bonding initiated at the peripheral regions of the crescent bond. The bond strength improved at higher substrate temperatures and

  16. Biogenic crust dynamics on sand dunes.

    PubMed

    Kinast, Shai; Meron, Ehud; Yizhaq, Hezi; Ashkenazy, Yosef

    2013-02-01

    Sand dunes are often covered by vegetation and biogenic crusts. Despite their significant role in dune stabilization, biogenic crusts have rarely been considered in model studies of dune dynamics. Using a simple model, we study the existence and stability ranges of different dune-cover states along gradients of rainfall and wind power. Two ranges of alternative stable states are identified: fixed crusted dunes and fixed vegetated dunes at low wind power; and fixed vegetated dunes and active dunes at high wind power. These results suggest a crossover between two different forms of desertification. PMID:23496449

  17. Dune-tastic

    NASA Technical Reports Server (NTRS)

    2006-01-01

    6 March 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a frosty, springtime scene in the north polar region of Mars. The area is blanketed by a maze of sand dunes; their appearance is enhanced by subliming, seasonal carbon dioxide frost.

    Location near: 80.2oN, 168.8oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

  18. Sojourner at Mermaid Dune

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This color image of the Sojourner rover was taken at the end of day on Sol 30. The rover is perched atop Mermaid Dune, a dark material distinct from the surrounding bright surface. Dark red rover tracks extend from the foreground to the base of the rover's wheels.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and managed the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  19. Integrated coastal dune management: checklists

    Microsoft Academic Search

    A. T Williams; J Alveirinho-Dias; F Garcia Novo; M. R Garc??a-Mora; R Curr; A Pereira

    2001-01-01

    The main objective was to assess dune vulnerability—a reduced ability to adapt to change, which is of serious concern not only in Western Europe but on a world scale. A main root checklist together with two daughter ones were devised in order to achieve this objective. The main root checklist comprised six categories (site and dune morphology, beach condition, surface

  20. Closeup of Mermaid Dune

    NASA Technical Reports Server (NTRS)

    1997-01-01

    This pair of images shows a broad view (upper image) and detailed close-up view (lower image) of the disturbed surface near and on Mermaid Dune. Seen slightly right of center in the upper image are two diggings by the rover's wheel. The uppermost rut is in the surface away from Mermaid and is considered to be typical of the surface at the landing site. The closer rut represents the surface at the base of Mermaid on the upwind side. The lower image is an enlargement of the disturbed Mermaid sediments plus those of the underlying substrate; that is, the ground upon which the dune lies. Seen in the close-up are at least two types of sediment, one that seems to be approximately 1.4 cm thick and forms piles with sides sloping at approximately 35 degrees, and another at least 3 cm deep composed of sediment that has a characteristic slope of 41 degrees when piled. It is apparent in the images that there is a size range of sediment present in the rut, sediment that ranges from a few millimeters in size down to below the resolution of the camera.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  1. Galle Cr. Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03637 Galle Cr. Dunes

    These dunes are located on the floor of Galle Crater.

    Image information: VIS instrument. Latitude 51.5S, Longitude 329.0E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  2. Brashear Cr. Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03645 Brashear Cr. Dunes

    This field of dunes is located on the floor of Brashear Crater.

    Image information: VIS instrument. Latitude 53.9S, Longitude 240.6E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  3. Proctor Cr. Dunes

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03293 Proctor Cr. Dunes

    This large dune field is located on the floor of Proctor Crater.

    Image information: VIS instrument. Latitude -47.4N, Longitude 30.7E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  4. Dunes on Plains

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03047 Dunes on Plains

    These dunes are located on the plains around Doanus Vallis.

    Image information: VIS instrument. Latitude 62.3S, Longitude 335.3E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  5. Holden Crater Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03192 Holden Crater Dunes

    These dunes occur on the floor of Holden Crater.

    Image information: VIS instrument. Latitude 25.8S, Longitude 326.5E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  6. Combined superior crescentic total glandular augmentation mastopexy: report of 37 cases

    Microsoft Academic Search

    Erdem Güven; Ali Sakinsel; Karaca Ba?aran; Memet Yazar; Mehmet Bozkurt; Samet Vasfi Kuvat

    Methods of periareolar, donut, or crescentic patterns for augmentation mastopexy in mild to moderate ptosis cases are minimally\\u000a invasive (short scar) options. In this article, we report a modified version of the classical crescentic technique of augmentation\\u000a mastopexy, namely, “superior crescentic total glandular augmentation mastopexy”. Thirty-seven patients with (a) breasts having\\u000a mild to moderate ptosis (Regnault grades I–II), (b) breasts

  7. Mesopotamian fertile crescent nearly gone, new study indicates

    NASA Astrophysics Data System (ADS)

    Showstack, Randy

    Something is terribly amiss in the marshlands of the fertile crescent of Mesopotamia, where the Tigris and Euphrates Rivers flow, and where Gilgamesh, the hero of an epic that dates at least as far back as the third millennium B.C., ruled.The marshlands, which are located primarily in Iraq and once extended between 15,000 and 20,000 square kilometers, now have been reduced to less than 1,500 to 2,000 square kilometers, according to a new study issued May 18 by the United Nations Environment Programme (UNEP). The marshlands could disappear in the near future if no immediate corrective actions are taken, according to Hassan Partow, the principal author of the UNEP study and a scientist within the agency's division of early warning and assessment.

  8. Numerical modeling of the wind flow over a transverse dune

    PubMed Central

    Araújo, Ascânio D.; Parteli, Eric J. R.; Pöschel, Thorsten; Andrade, José S.; Herrmann, Hans J.

    2013-01-01

    Transverse dunes, which form under unidirectional winds and have fixed profile in the direction perpendicular to the wind, occur on all celestial objects of our solar system where dunes have been detected. Here we perform a numerical study of the average turbulent wind flow over a transverse dune by means of computational fluid dynamics simulations. We find that the length of the zone of recirculating flow at the dune lee — the separation bubble — displays a surprisingly strong dependence on the wind shear velocity, u*: it is nearly independent of u* for shear velocities within the range between 0.2?m/s and 0.8?m/s but increases linearly with u* for larger shear velocities. Our calculations show that transport in the direction opposite to dune migration within the separation bubble can be sustained if u* is larger than approximately 0.39?m/s, whereas a larger value of u* (about 0.49?m/s) is required to initiate this reverse transport. PMID:24091456

  9. Dune and Dust Devil Streaks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-474, 5 September 2003

    This August 2003 Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) picture shows a dark sand dune on the floor of a crater at 54.9oS, 342.5oW. Recent dust devils have disrupted a thin coating of dust on the otherwise dark dune; these wind phenomena created the plethora of markings and streaks on the dune. The image covers an area 3 km (1.9 mi) across and is illuminated by sunlight from the upper left.

  10. Dune Activity in Proctor Crater

    NASA Technical Reports Server (NTRS)

    1999-01-01

    Observation of dune activity--whether the movement of whole dunes or the movement of sediment on a dune--is the result of a direct link between the martian surface and its atmosphere. Observation of dune activity can be used to determine the rate at which wind moves sediment. It can also help to estimate how long it takes for windblown sand to abrade surfaces--including rocks and Mars landers.

    One of the first sand dune fields ever recognized on Mars is shown here. Located on the floor of Proctor Crater (at 48oS, 330oW), this dune field was seen in Mariner 9images more than 27 years ago. In fact, the photomosaic base map in MOC2-170a (above, left) is constructed from Mariner 9 images taken in February and March of 1972. The thin strip overlain on the Mariner 9 mosaic is a Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image taken in June 1999. The new MOC image shows evidence that the Proctor Crater dunes are active today.

    The picture on the right is an expanded view of a portion of the MOC image (its location is indicated by the white box in the picture on the left). In this view (right), the sand dunes are dark and patches of southern winter frost are bright. The sun illuminates the scene from the upper left. Dark streaks can be seen on frost-covered slopes, particularly just left of the center of the picture. Thesestreaks result from recent avalanching of sand on the steep (up to 35o), down-wind side of the dune, otherwise known as the slip face. Because the dark sand streaks are superposed upon the bright frost, these streaks can only be as old as the frost. This frost cannot be more than 11 months old, and was probably only a few months old at the time the picture was taken. Thus, the dunes must be active today in order to show such streaks.

    The placement of dunes in the MOC image was also compared with their positions in the earlier Mariner 9 image (above, left). No evidence that entire dunes have moved since March 1972 has been found. While the period of March 1972 to June 1999 is 27 Earth years, it is only about 14 Mars years. Looking for evidence of dune movement since 1972 is limited by the fact that the Mariner 9 images have spatial resolutions of about 62 meters (203 feet) per pixel--this means that the dunes would have to move more than about 62 meters before their motion could be clearly detected in a MOC image.

    Taking the two results together--evidence for recent dune activity in the form of avalanches on slip faces versus lack of movement at the scale of 62 meters--helps to establish that (a) the dunes are active, but (b) they moved less than approximately 62 meters in 14 Mars years.

    The 8 kilometer scale (upper left) indicates a distance of 5.0 miles. The 300 meter scale bar (lower right) represents 328 yards (984 feet). The Mariner 9 images are illuminated from the upper right, the MOC image from the upper left.

    Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.

  11. Low-Dose Local Kidney Irradiation Inhibits Progression of Experimental Crescentic Nephritis by Promoting Apoptosis

    Microsoft Academic Search

    Diange Liu; Arifa Nazneen; Takashi Taguchi; M. Shawkat Razzaque

    2008-01-01

    Background: Crescentic glomerulonephritis is a rapidly progressive form of nephritis and is usually resistant to therapeutic intervention. Apoptosis plays a role in the resolution of glomerulonephritis. We investigated the effects of local kidney irradiation on the progression of experimental crescentic glomerulonephritis. Methods: The following three experimental rat groups were generated: (1) Group I, sham-operated control (n = 12); (2) Group

  12. Water Vapor Transport and the Production of Precipitation in the Eastern Fertile Crescent

    E-print Network

    Evans, Jason

    Water Vapor Transport and the Production of Precipitation in the Eastern Fertile Crescent J. P to quantify the significance of southerly water vapor fluxes on precipitation occurring in the eastern Fertile Crescent region. The water vapor fluxes were investigated at high temporal and spatial resolution by using

  13. Solar

    NSDL National Science Digital Library

    Iowa Public Television. Explore More Project

    2004-01-01

    What part does solar energy play in satisfying energy demands? This informational piece, part of a series about the future of energy, introduces students to solar energy. Here students read about the uses, benefits, and active and passive methods of solar energy. Information is also presented about limitations, geographical considerations of solar power in the United States, and current uses of solar energy around the world. Thought-provoking questions afford students chances to reflect on what they've read about the uses of solar energy. Articles and information about a solar power plant in the Mohave Desert, the use of solar energy in Iowa, and statistics about solar energy are provided in a sidebar.

  14. Channels on Dunes in Russell Crater

    NASA Technical Reports Server (NTRS)

    2006-01-01

    Hundreds of enigmatic small channels are seen to carve into the slopes of these dark sand dunes lying within Russell Crater on Mars. These features were previously identified as gullies in images from the Mars Orbiter Camera (MOC) on Mars Global Surveyor, but the higher resolution HiRISE image brings out many new details and mysteries. The channels extend from near the top of the dunes to their bases, indicating that some fluid material carved into the sand. The channels commonly begin as smaller tributaries joined together, suggesting several sources of fluid. Distinct dark spots are located near where the channels seem to originate. Several channels appear to originate at alcoves. Several of these channels have sinuous middle reaches while others are straighter. Further down slope, some channel edges appear elevated above the surrounding terrain, particularly in the lower reaches. The channels seem to terminate abruptly, with no deposition of material, unlike at the bases of some other gullies on Mars that are not on dunes.

    One hypothesis for the origin of the channels, which has previously been proposed by the MOC team, is that CO2 (or maybe H2O) frost is deposited on the dunes in shadows or at night. Some frost may also be incorporated into the internal parts of the dunes due to natural avalanching. When the frost is eventually heated by sunlight, rapid sublimation triggers an avalanche of fluidized sand, forming a gully. HiRISE will continue to target small channel features such as these and may return to search for any changes over time.

    Image PSP_001440_1255 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on November 16, 2006. The complete image is centered at -54.2 degrees latitude, 12.9 degrees East longitude. The range to the target site was 251.4 km (157.1 miles). At this distance the image scale is 50.3 cm/pixel (with 2 x 2 binning) so objects 151 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel and north is up. The image was taken at a local Mars time of 3:41 PM and the scene is illuminated from the west with a solar incidence angle of 85 degrees, thus the sun was about 5 degrees above the horizon. At a solar longitude of 136.3 degrees, the season on Mars is Northern Summer.

    NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter for NASA's Science Mission Directorate, Washington. Lockheed Martin Space Systems, Denver, is the prime contractor for the project and built the spacecraft. The High Resolution Imaging Science Experiment is operated by the University of Arizona, Tucson, and the instrument was built by Ball Aerospace and Technology Corp., Boulder, Colo.

  15. COMPORTEMENT EN TEMPS LONG D'UNE NANOPARTICULE Comportement en temps long d'une

    E-print Network

    Gentil, Ivan

    COMPORTEMENT EN TEMPS LONG D'UNE NANO­PARTICULE Comportement en temps long d'une nano SEPTEMBRE 2012 1 / 30 #12;COMPORTEMENT EN TEMPS LONG D'UNE NANO­PARTICULE Plan 1 Introduction 2 SEPTEMBRE 2012 2 / 30 #12;COMPORTEMENT EN TEMPS LONG D'UNE NANO­PARTICULE The physical problem I Model

  16. Dunes and Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    22 August 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a suite of dark sand dunes that formed in winds blowing from east (right) to west (left), along with smaller, lighter-toned ripples and many dark dust devil tracks. The dust devil tracks indicate movement from a variety of directions, while the dunes only indicate winds from the east. In the lower left quarter of the image, dune sand has flowed around a layered rock obstacle. This scene is located near 19.9oN, 280.5oW. The image covers an area about 3 km (1.9 mi) across and sunlight illuminates the scene from the lower left.

  17. Dunes and Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-352, 6 May 2003

    March 6, 2003, is the first day of spring in the martian southern hemisphere. As spring progresses in the south, dust devils will begin to form and sweep up some of the veneer of bright dust that accumulated during the recent autumn and winter seasons.

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows sand dunes in Wirtz Crater. The dark streaks that criss-cross each dune were probably formed by passing dust devils that disrupted or removed some of the thin layer of dust that coats the dunes. The picture covers an area about 3 km (1.9 mi) wide near 48.3oS, 25.4oW. Sunlight illuminates the scene from the upper left.

  18. Dune and Dust Devil Tracks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    31 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a dark sand dune patch that occurs on the floor of a southern hemisphere crater near 64.1oS, 197.2oW. Passing dust devils have disrupted the fine, bright dust that coats the surrounding terrain, leaving wildly-varied streak patterns. Dark dots to the left (west) of the dune are boulders. The picture covers an area 3 km (1.9 mi) wide; sunlight illuminates the scene from the upper left.

  19. Moreux Crater Dunes

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The THEMIS VIS camera is capable of capturing color images of the Martian surface using five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from using multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    This false color image shows part of the interior of Moreux Crater. The crater peak is at the right edge of the image. Many dunes and a dunefield are also visible in the iamge. This image was collected during the Northern Spring season.

    Image information: VIS instrument. Latitude 41.9, Longitude 44.1 East (315.9 West). 35 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  20. Genesis of coastal dune fields with vegetation

    Microsoft Academic Search

    M. Luna; Eric J. R. Parteli; Orencio Duran; Hans J. Herrmann; Xavier Sigaud

    2010-01-01

    Vegetation greatly affects the formation and dynamics of dune fields in coastal areas. In the present work, we use dune modelling in order to investigate the genesis and early development stages of costal dune fields in the presence of vegetation. The model, which consists of a set of coupled equations for the turbulent wind field over the landscape, the saltation

  1. [A systematic analysis of the Ottoman Red Crescent periodical (part II)].

    PubMed

    Okutan, Y

    2001-01-01

    Founded in 1877, the Ottoman Red Crescent Society rendered a lot of important services in military and civil areas in the Ottoman Empire. The Ottoman Red Crescent Society not only gave health services for the soldiers, but it also attempted to obey the international acts signed for the captives and to rescue them together with the countries involved under the supervision of the international Red Cross. In the civilian area, the Ottoman Red Crescent Society also played an active role to meet the casualties' needs, such as food, clothes, and accommodation following natural disasters like earthquake, flood, fire etc. Ottoman Red Crescent Society published a monthly newsletter called Osmanli Hilâl-i Ahmer Mecmuasi to announce its services more effectively to the public since 15 September 1921 (12 Muharrem 1340). The publication of the newsletter continued as Türkiye Hilâl-i Ahmer Mecmuasi after the 15th issue. Starting with the 85th issue on September 15th, 1928 (30 Rebiülevvel 1347) it was printed with Latin alphabet instead of Arabic letters. A brief translation in French and in English exist in the end of each issue. In the second part of this research, news about the Red Crescent Society's organization; financial supports for the Society and, in return, material and financial aids by she Society; local organizations providing aid to the Society; money collected during Bairams; plays and balls arranged by the Society; and the activities of the womens' branch of the Red Crescent Society, are introduced. PMID:14570020

  2. Enlarge Image Dune buggy. The

    E-print Network

    Goodisman, Michael

    in Atlanta, found a happy medium. They noticed that the limbs of a variety of desert animals, includingEnlarge Image Dune buggy. The SandBot mimics desert animals that move rapidly across sand. CREDIT that mimics the locomotion of desert animals, allowing it to traverse loose terrain with ease. If perfected

  3. Contrast Threshold of Lunar Crescents Visibility for Ramadan and Syawal 1431 H at Bosscha Observatory

    NASA Astrophysics Data System (ADS)

    Arumaningtyas, E. P.; Raharto, M.

    2010-12-01

    In this paper we present the prediction of the first lunar crescent visibility using contrast based on Schaefer's model and best time proposed by [12] for the beginning of Ramadhan and Syawal 1431 H at observing place in Bosscha Observatory, [E 107° 36.96', S 6° 49.55', with elevation of 1310 meters above sea level]. The geocentric altitude of the Moon at the sunset time on August 10 is 1° 58.98' and illuminated fraction of crescent (FI) = 0.20%. On August 11, 2010 the altitude of the Moon at the sunset time is 15° 42.71' and FI = 2.57%. The calculated contrast on August 10, 2010 is less than zero. It means that the brightness of the moon is smaller than brightness of the sky. Based on the contrast value, it is impossible to observe the lunar crescent by the naked eye at that time, even equipped by special design telescope for the crescent observation at Bosscha Observatory. Sultan [11] proposed a predicted model it is still possible to observe the very young lunar crescent even under circumstance before the time of sunset, if the contrast of sky is perfect. On August 11, 2010 contrast has its maximum at 50 minutes after sunset. The result of observation of the lunar crescent at Bosscha Observatory, the crescent could be seen before sunset at 17.15 local time (UT+7 hours) using special design telescope with additional nose of 1 meter length [6]. The model used here is tend to predict the brightness for naked eye observation, which less contrast compare to observation with the well design telescope.

  4. [A systematic analysis of the Ottoman Red Crescent periodical (Part III)].

    PubMed

    Okutan, Yahya

    2002-01-01

    Founded in 1877, the Ottoman Red Crescent Society rendered a lot of important services in military and civil areas in the Ottoman Empire. The Ottoman Red Crescent Society not only gave health services for the soldiers, but it also attempted to obey the international acts signed for the war captives and to rescue them together with the countries involved under the supervision of the international Red Cross. In the civilian area, the Ottoman Red Crescent Society also played an active role to meet the casualties' needs, such as food, clothes, and accommodation following natural disasters like earthquake, flood, fire etc. The Ottoman Red Crescent Society published a monthly newsletter called Osmanli Hilâl-i Ahmer Mecmuasi to announce its services more effectively to the public since 15 September 1921 (12 Muharrem 1340). The publication of the newsletter continued as Türkiye Hilâl-i Ahmer Mecmuas' after the 15th issue. Starting with the 85th issue on September 15th, 1928 (30 Rebiülevvel 1347) it was printed with Latin alphabet instead of Arabic letters. A brief translation in French and in English exist in the end of each issue. In the second part of this research, news about the Red Crescent Society's organization; financial supports for the Society and, in return, material and financial aids by the Society; local organizations providing aid to the Society; money collected during Bairams; plays and balls arranged by the Society; and the activities of the womens' branch of the Red Crescent Society, are introduced. The third and last part of the study deals with the comments of visitors about the Red Crescent Society; and news and activities of the European Red Cross Societies. PMID:17152156

  5. Mars global digital dune database: MC-30

    USGS Publications Warehouse

    Hayward, R.K.; Fenton, L.K.; Titus, T.N.; Colaprete, A.; Christensen, P.R.

    2012-01-01

    The Mars Global Digital Dune Database (MGD3) provides data and describes the methodology used in creating the global database of moderate- to large-size dune fields on Mars. The database is being released in a series of U.S. Geological Survey Open-File Reports. The first report (Hayward and others, 2007) included dune fields from lat 65° N. to 65° S. (http://pubs.usgs.gov/of/2007/1158/). The second report (Hayward and others, 2010) included dune fields from lat 60° N. to 90° N. (http://pubs.usgs.gov/of/2010/1170/). This report encompasses ~75,000 km2 of mapped dune fields from lat 60° to 90° S. The dune fields included in this global database were initially located using Mars Odyssey Thermal Emission Imaging System (THEMIS) Infrared (IR) images. In the previous two reports, some dune fields may have been unintentionally excluded for two reasons: (1) incomplete THEMIS IR (daytime) coverage may have caused us to exclude some moderate- to large-size dune fields or (2) resolution of THEMIS IR coverage (100 m/pixel) certainly caused us to exclude smaller dune fields. In this report, mapping is more complete. The Arizona State University THEMIS daytime IR mosaic provided complete IR coverage, and it is unlikely that we missed any large dune fields in the South Pole (SP) region. In addition, the increased availability of higher resolution images resulted in the inclusion of more small (~1 km2) sand dune fields and sand patches. To maintain consistency with the previous releases, we have identified the sand features that would not have been included in earlier releases. While the moderate to large dune fields in MGD3 are likely to constitute the largest compilation of sediment on the planet, we acknowledge that our database excludes numerous small dune fields and some moderate to large dune fields as well. Please note that the absence of mapped dune fields does not mean that dune fields do not exist and is not intended to imply a lack of saltating sand in other areas. Where availability and quality of THEMIS visible (VIS), Mars Orbiter Camera (MOC) narrow angle, Mars Express High Resolution Stereo Camera, or Mars Reconnaissance Orbiter Context Camera and High Resolution Imaging Science Experiment images allowed, we classified dunes and included some dune slipface measurements, which were derived from gross dune morphology and represent the approximate prevailing wind direction at the last time of significant dune modification. It was beyond the scope of this report to look at the detail needed to discern subtle dune modification. It was also beyond the scope of this report to measure all slipfaces. We attempted to include enough slipface measurements to represent the general circulation (as implied by gross dune morphology) and to give a sense of the complex nature of aeolian activity on Mars. The absence of slipface measurements in a given direction should not be taken as evidence that winds in that direction did not occur. When a dune field was located within a crater, the azimuth from crater centroid to dune field centroid was calculated, as another possible indicator of wind direction. Output from a general circulation model is also included. In addition to polygons locating dune fields, the database includes ~700 of the THEMIS VIS and MOC images that were used to build the database.

  6. Extraterrestrial dunes: An introduction to the special issue on planetary dune systems

    E-print Network

    Bourke, Mary C.

    Extraterrestrial dunes: An introduction to the special issue on planetary dune systems Mary C on extraterrestrial surfaces are similar to those on Earth, although some have notable differences in bedform scale

  7. Growth mechanisms and dune orientation on Titan

    NASA Astrophysics Data System (ADS)

    Lucas, Antoine; Rodriguez, Sebastien; Narteau, Clement; Cahrnay, Benjamin; Courrech du Pont, Sylvain; Tokano, Tetsuya; Garcia, Amandine; Thiriet, Melanie; Hayes, Alexander; Lorenz, Ralph; Aharonson, Oded

    2015-04-01

    Dune fields on Titan cover more than 17 % of the moon's surface, constituting the largest known surface reservoir of organics. Their confinement to the equatorial belt, shape, and eastward direction of propagation offer crucial information regarding both the wind regime and sediment supply. Herein, we present a comprehensive analysis of Titan's dune orientations using automated detection techniques on non-local denoised radar images. By coupling a new dune growth mechanism with actual wind fields generated by climate modelling, we find that Titan's dunes grow by elongation on a non-mobile substratum. To be fully consistent with both the local crestline orientations and the eastward propagation of Titan's dunes, the sediment should be predominantly transported by strong eastward winds, most likely generated by equinoctial storms or occasional fast westerly gusts. Additionally, convergence of the meridional transport predicted in models can explain why Titan's dunes are confined within plus or minus 30 deg. latitudes, where sediment fluxes converge.

  8. Growth mechanisms and dune orientation on Titan

    NASA Astrophysics Data System (ADS)

    Lucas, Antoine; Rodriguez, Sébastien; Narteau, Clément; Charnay, Benjamin; Pont, Sylvain Courrech; Tokano, Tetsuya; Garcia, Amandine; Thiriet, Mélanie; Hayes, Alexander G.; Lorenz, Ralph D.; Aharonson, Oded

    2014-09-01

    Dune fields on Titan cover more than 17% of the moon's surface, constituting the largest known surface reservoir of organics. Their confinement to the equatorial belt, shape, and eastward direction of propagation offer crucial information regarding both the wind regime and sediment supply. Herein, we present a comprehensive analysis of Titan's dune orientations using automated detection techniques on nonlocal denoised radar images. By coupling a new dune growth mechanism with wind fields generated by climate modeling, we find that Titan's dunes grow by sediment transport on a nonmobile substratum. To be fully consistent with both the local crestline orientations and the eastward propagation of Titan's dunes, the sediment should be predominantly transported by strong eastward winds, most likely generated by equinoctial storms or occasional fast westerly gusts. Additionally, convergence of the meridional transport predicted in models can explain why Titan's dunes are confined within ±30° latitudes, where sediment fluxes converge.

  9. Development and stability of bed forms: a numerical analysis of dune pattern coarsening and giant dunes

    NASA Astrophysics Data System (ADS)

    Gao, Xin; Narteau, Clement; Rozier, Olivier

    2015-04-01

    We investigate the development and stability of transverse dunes for ranges of flow depths and velocities using a cellular automaton dune model. Subsequent to the initial bed instability, dune pattern coarsening is driven by bed form interactions. Collisions lead to two types of coalescence associated with upstream or downstream dominant dunes. In addition, a single collision-ejection mechanism enhances the exchange of mass between two consecutive bed forms (through-passing dunes). The power-law increases in wavelength and amplitude exhibit the same exponents, which are independent of flow properties. Contrary to the wavelength, dune height is not only limited by flow depth but also by the strength of the flow. Superimposed bedforms may propagate and continuously destabilize the largest dunes. Then, we identify three classes of steady-state transverse dune fields according to the periodicity in crest-to-crest spacing and the mechanism of size limitation. In all cases, the steady state is reached when the bed shear stress in the dune trough regions is close to its critical value for motion inception. Such a critical shear stress value is reached and maintained through the dynamic equilibrium between flow strength and dune aspect ratio. Comparisons with natural dune fields show that many of them may have reached such a steady state. Finally, we infer that the sedimentary patterns in the model may be used to bring new constraints on the stability of modern and ancient dune fields.

  10. Prediction of Outcomes in Crescentic IgA Nephropathy in a Multicenter Cohort Study

    PubMed Central

    Lv, Jicheng; Yang, Yihe; Chen, Wenfang; Pan, Xiaoxia; Guo, Zhiling; Wang, Caili; Li, Shen; Zhang, Jianrong; Zhang, Jianchun; Liu, Lijun; Shi, Sufang; Wang, Suxia; Chen, Min; Cui, Zhao; Chen, Nan; Yu, Xueqing; Zhao, MingHui; Wang, Haiyan

    2013-01-01

    Crescentic IgA nephropathy (IgAN), defined as >50% crescentic glomeruli on kidney biopsy, is one of the most common causes of rapidly progressive GN. However, few studies have characterized this condition. To identify risk factors and develop a prediction model, we assessed data from patients?14 years old with crescentic IgAN who were followed ?12 months. The discovery cohort comprised 52 patients from one kidney center, and the validation cohort comprised 61 patients from multiple centers. At biopsy, the mean serum creatinine (SCr) level ± SD was 4.3±3.4 mg/dl, and the mean percentage of crescents was 66.4%±15.8%. The kidney survival rates at years 1, 3, and 5 after biopsy were 57.4%±4.7%, 45.8%±5.1%, and 30.4%±6.6%, respectively. Multivariate Cox regression revealed initial SCr as the only independent risk factor for ESRD (hazard ratio [HR], 1.32; 95% confidence interval [CI], 1.10 to 1.57; P=0.002). Notably, the percentage of crescents did not associate independently with ESRD. Logistic regression showed that the risk of ESRD at 1 year after biopsy increased rapidly at SCr>2.7 mg/dl and reached 90% at SCr>6.8 mg/dl (specificity=98.5%, sensitivity=64.6% for combined cohorts). In both cohorts, patients with SCr>6.8 mg/dl were less likely to recover from dialysis. Analyses in additional cohorts revealed a similar association between initial SCr and ESRD in patients with antiglomerular basement membrane disease but not ANCA-associated systemic vasculitis. In conclusion, crescentic IgAN has a poor prognosis, and initial SCr concentration may predict kidney failure in patients with this disease. PMID:24029421

  11. Prediction of outcomes in crescentic IgA nephropathy in a multicenter cohort study.

    PubMed

    Lv, Jicheng; Yang, Yihe; Zhang, Hong; Chen, Wenfang; Pan, Xiaoxia; Guo, Zhiling; Wang, Caili; Li, Shen; Zhang, Jianrong; Zhang, Jianchun; Liu, Lijun; Shi, Sufang; Wang, Suxia; Chen, Min; Cui, Zhao; Chen, Nan; Yu, Xueqing; Zhao, Minghui; Wang, Haiyan

    2013-12-01

    Crescentic IgA nephropathy (IgAN), defined as >50% crescentic glomeruli on kidney biopsy, is one of the most common causes of rapidly progressive GN. However, few studies have characterized this condition. To identify risk factors and develop a prediction model, we assessed data from patients ? 14 years old with crescentic IgAN who were followed ? 12 months. The discovery cohort comprised 52 patients from one kidney center, and the validation cohort comprised 61 patients from multiple centers. At biopsy, the mean serum creatinine (SCr) level ± SD was 4.3 ± 3.4 mg/dl, and the mean percentage of crescents was 66.4%± 15.8%. The kidney survival rates at years 1, 3, and 5 after biopsy were 57.4%± 4.7%, 45.8%± 5.1%, and 30.4%± 6.6%, respectively. Multivariate Cox regression revealed initial SCr as the only independent risk factor for ESRD (hazard ratio [HR], 1.32; 95% confidence interval [CI], 1.10 to 1.57; P=0.002). Notably, the percentage of crescents did not associate independently with ESRD. Logistic regression showed that the risk of ESRD at 1 year after biopsy increased rapidly at SCr>2.7 mg/dl and reached 90% at SCr>6.8 mg/dl (specificity=98.5%, sensitivity=64.6% for combined cohorts). In both cohorts, patients with SCr>6.8 mg/dl were less likely to recover from dialysis. Analyses in additional cohorts revealed a similar association between initial SCr and ESRD in patients with antiglomerular basement membrane disease but not ANCA-associated systemic vasculitis. In conclusion, crescentic IgAN has a poor prognosis, and initial SCr concentration may predict kidney failure in patients with this disease. PMID:24029421

  12. Coastal dune stability: The effect of meteorological conditions and vegetation

    Microsoft Academic Search

    B. G. Watt

    1977-01-01

    Quantitative investigations and research conducted along the north coast of New South Wales, Australia are evaluated with respect to coastal processes, coastal alignment, meteorological data, dune dimensions, dune vegetative cover, development on the dunal area and dune management.

  13. Hematite Outlier and Sand Dunes

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 4 December 2003

    This image shows a crater just south of the edge of the famous hematite-bearing surface, which is visible in the context image as a smooth area to the north. The crater has two features of immediate note. The first is a layered mound in the north part of the crater floor. This mound contains hematite, and it is an outlying remnant of the greater deposits to the north that have otherwise completely disappeared in this crater. The second feature is a dune field in the center of the crater floor, with dark dunes indicating winds from the northwest. The dunes grade into a dark sand sheet with no coherent structure, indicating that the sand layer thins out to the south and east.

    Image information: VIS instrument. Latitude -4.4, Longitude 357.3 East (2.7 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  14. Pathfinder Rover Atop Mermaid Dune

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Mars Pathfinder Lander camera image of Sojourner Rover atop the Mermaid 'dune' on Sol 30. Note the dark material excavated by the rover wheels. These, and other excavations brought materials to the surface for examination and allowed estimates of mechanical properties of the deposits.

    NOTE: original caption as published in Science Magazine

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages the Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is a division of the California Institute of Technology (Caltech).

  15. Defrosting North Polar Dune Field

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-331, 15 April 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image captures frost-covered north polar sand dunes in springtime as they are beginning to defrost. Dark spots and streaks indicate areas where frozen carbon dioxide has started to be removed by sublimation and wind. The picture covers an area 3 km (1.9 mi) wide near 76.3oN, 264.9oW. Sunlight illuminates the scene from the lower left.

  16. Invasive plants on disturbed Korean sand dunes

    Microsoft Academic Search

    K. D. Kim

    2005-01-01

    The sand dunes in coastal regions of South Korea are important ecosystems because of their small size, the rare species found in this habitat, and the beautiful landscapes they create. This study investigated the current vegetative status of sand dunes on three representative coasts of the Korean peninsula, and on the coasts of Cheju Island, and assessed the conditions caused

  17. Expression of Ser729 Phosphorylated PKC Epsilon in Experimental Crescentic Glomerulonephritis: An Immunohistochemical Study

    PubMed Central

    Karavana, V.N.; Gakiopoulou, H.; Lianos, E.A.

    2014-01-01

    PKC?, a DAG-dependent, Ca2+- independent kinase attenuates extent of fibrosis following tissue injury, suppresses apoptosis and promotes cell quiescence. In crescentic glomerulonephritis (CGN), glomerular epithelial cells (GEC) contribute to fibro-cellular crescent formation while they also transdifferentiate to a mesenchymal phenotype. The aim of this study was to assess PKC? expression in CGN. Using an antibody against PKC-? phosphorylated at Ser729, we assessed its localization in rat model of immune-mediated rapidly progressive CGN. In glomeruli of control animals, pPKC? was undetectable. In animals with CGN, pPKC? was expressed exclusively in glomerular epithelial cells (GEC) and in GEC comprising fibrocellular crescents that had acquired a myofibroblasttype phenotype. In non-immune GEC injury induced by puromycin aminonucleoside and resulting in proteinuria of similar magnitude as in CGN, pPKC? expression was absent. There was constitutive pPKC? expression in distal convoluted tubules, collecting ducts and thick segments of Henley’s loops in both control and experimental animals. We propose that pPKC? expression occurring in GEC and in fibrocellular crescentic lesions in CGN may facilitate PKC? dependent pathologic processes. PMID:24998921

  18. Kuril Islands tsunami of November 2006: 1. Impact at Crescent City by distant scattering

    E-print Network

    Kowalik, Zygmunt

    Kuril Islands tsunami of November 2006: 1. Impact at Crescent City by distant scattering Z. Kowalik November 2007; published 31 January 2008. [1] A numerical model for the global tsunami computation constructed by Kowalik et al. (2005, 2007a) is applied to the tsunami of November 15, 2006 in the northern

  19. Epidemiology of the optic nerve grey crescent in the Reykjavik Eye Study

    Microsoft Academic Search

    O Jonsson; K F Damji; F Jonasson; A Arnarsson; T Eysteinsson; H Sasaki; K Sasaki

    2005-01-01

    Aim: To establish the epidemiology of the grey crescent in a white population within the age range most susceptible to glaucoma.Methods: Bruce Shields was first to use this term to describe a localised, physiological pigmentation of the optic nerve neuroretinal rim tissue that is distinct from peripapillary pigmentation. An experienced glaucomatologist (KFD) evaluated stereofundus photographs of the participants of the

  20. Zooplankton Diel Vertical Distributions in Lake Crescent, a Deep Oligotrophic Lake in Washington (USA)

    Microsoft Academic Search

    Jonathan D. Rainey; William V. Sobczak; Steven C. Fradkin

    2007-01-01

    We evaluated diel vertical migration (DVM) of major zooplankton populations in Lake Crescent, Washington, a deep oligotrophic lake where this phenomenon has not previously been studied. Duplicate daytime and nighttime samples were collected on June 27 and August 1, 2003 at ten depth intervals spanning 0–140 m. The major zooplankton taxa were the crustaceans Diaptomus tyrrelli, Daphnia rosea, Holopedium gibberum

  1. [A systematic analysis of the Ottoman Red Crescent periodical (part I)].

    PubMed

    Okutan, Y

    2000-01-01

    Founded in 1877, the Ottoman Red Crescent Society rendered a lot of important services in military and civil areas in the Ottoman Empire. The Ottoman Red Crescent Society not only gave health services for the soldiers, but it also attempted to obey the international acts signed for the war captives and to rescue them together with the counties involved under the supervision of the international Red Cross. In tbe civilian area, the Ottoman Red Crescent Society also played an active role to meet the casualties' needs, such as food, clothes, and accommodation following natural disaster like earthquake, flood, fire etc. The Ottoman Red Crescent Society published a rnonthly newsletter called Osmanli Hilâl-i Ahmer Mecmuasi to announce its services more effectively to the public since 15 September 1921 (12 Muharrem 1346). The publication of the newsletter continued as Türkiye Hilâl-i Ahmer Mecmuasi after the 15th issue. Starting with the 85th issue on September 15th, 1928 (30 Rebiülevvel 1347) it was printed with Latin alphabet instead of Arabic letters. A brief translation in French and in English exist in the end of each issue. PMID:14567382

  2. Ecogeomorphology of Sand Dunes Shaped by Vegetation

    NASA Astrophysics Data System (ADS)

    Tsoar, H.

    2014-12-01

    Two dune types associated with vegetation are known: Parabolic and Vegetated Linear Dunes (VLDs), the latters are the dominant dune type in the world deserts. Parabolic dunes are formed in humid, sub-humid and semi-arid environments (rather than arid) where vegetation is nearby. VLDs are known today in semiarid and arid lands where the average yearly rainfall is ?100 mm, enough to support sparse cover of vegetation. These two dune types are formed by unidirectional winds although they demonstrate a different form and have a distinct dynamics. Conceptual and mathematical models of dunes mobility and stability, based on three control parameters: wind power (DP), average annual precipitation (p), and the human impact parameter (?) show that where human impact is negligible the effect of wind power (DP) on vegetative cover is substantial. The average yearly rainfall of 60-80 mm is the threshold of annual average rainfall for vegetation growth on dune sand. The model is shown to follow a hysteresis path, which explains the bistability of active and stabilized dunes under the same climatic conditions with respect to wind power. We have discerned formation of parabolic dunes from barchans and transverse dunes in the coastal plain of Israel where a decrease in human activity during the second half of the 20th century caused establishment of vegetation on the crest of the dunes, a process that changed the dynamics of these barchans and transverse dunes and led to a change in the shape of the windward slope from convex to concave. These dunes gradually became parabolic. It seems that VLDs in Australia or the Kalahari have always been vegetated to some degree, though the shrubs were sparser in colder periods when the aeolian erosion was sizeable. Those ancient conditions are characterized by higher wind power and lower rainfall that can reduce, but not completely destroy, the vegetation cover, leading to the formation of lee (shadow) dunes behind each shrub. Formation of such VLDs can occur today in some coasts where the wind is quite strong and the rain can support some shrubs.

  3. Minimal model for aeolian sand dunes

    E-print Network

    Klaus Kroy; Gerd Sauermann; Hans J. Herrmann

    2002-03-02

    We present a minimal model for the formation and migration of aeolian sand dunes. It combines a perturbative description of the turbulent wind velocity field above the dune with a continuum saltation model that allows for saturation transients in the sand flux. The latter are shown to provide the characteristic length scale. The model can explain the origin of important features of dunes, such as the formation of a slip face, the broken scale invariance, and the existence of a minimum dune size. It also predicts the longitudinal shape and aspect ratio of dunes and heaps, their migration velocity and shape relaxation dynamics. Although the minimal model employs non-local expressions for the wind shear stress as well as for the sand flux, it is simple enough to serve as a very efficient tool for analytical and numerical investigations and to open up the way to simulations of large scale desert topographies.

  4. Vegetated linear dunes - chronologically discontinuous archives of several short-term and major dune growth episodes

    NASA Astrophysics Data System (ADS)

    Roskin, Joel

    2013-04-01

    Quartz sand dunes cover massive areas defined as arid, making them a potentially important archive of past climates and environments. But, dunes, being highly dynamic and relatively uniform in sedimentological composition, often compromise this potential. Most inland dunes are of the linear type that has a sinuous planar shape. Linear dunes, also associated with active seif dunes, are elongated by oblique cross-(dune) crest deflection of sand grains due to acutely bimodal sand-transporting winds. This prevents formation of long-term and stratigraphically continuous internal dune structure (though fully exposed internal linear dune structures to support this conclusion are rarely found). Therefore, dating of the dune sand by luminescence methods is mainly restricted to the last (re)mobilization phase and cannot track earlier dune growth history. Vegetated linear dunes (VLDs), mainly found in low-latitudes, are characterized by a straight planar shape and a partial shrub cover, and have been proposed to comprise an independent dune type. The stratigraphic cross-section of the VLD includes a sequence of chronologically discontinuous sand units forming the dune core. The accumulation of the units is generally interpreted to pertain to major episodes of strong wind power when sand was available. Possible minor events of sand accumulation are presumed to have been erased by major episodes. The units, often structureless and of similar sedimentological properties can only be discerned by luminescence dating as contacts between units do not necessarily imply chronological boundaries. The VLD core is overlaid by a mantle of sand that while being intermittently morphologically and structurally configured by seasonal winds to depths of several meters, preserves the dune core stratigraphy. Therefore, in a sense, the VLD is a prominent sedimentary body archiving influential short-time and possibly extreme events. Based upon exposed dune stratigraphy, ground-penetrating radar profiling and morphologic analysis, coupled with spatial dense optically stimulated luminescence (OSL) dated full dune cores, the VLD core structure is found to repeat itself in the northwestern Negev (Israel) dunefield, for three time orders, each representing different palaeoclimatic and palaeoenvironmental conditions. Accordingly, a full dune core coring strategy for retrieving luminescence ages which date the major VLD core units is required for adequately dating a vegetated linear dunefield. Exposed sections of VLD cores that reveal the full dune core structure are very important for such dating strategies. The VLD type is suggested to inherently comprise a distinct archive of unique past conditions, mainly since the last glacial. However, further study is required for robust palaeoclimatic interpretation of these archives.

  5. Conceptual models of the evolution of transgressive dune field systems

    NASA Astrophysics Data System (ADS)

    A. Hesp, Patrick

    2013-10-01

    This paper examines the evolutionary paths of some transgressive dune fields that have formed on different coasts of the world, and presents some initial conceptual models of system dynamics for transgressive dune sheets and dune fields. Various evolutionary pathways are conceptualized based on a visual examination of dune fields from around the world. On coasts with high sediment supply, dune sheets and dune fields tend to accumulate as large scale barrier systems with little colonization of vegetation in arid-hyper to arid climate regimes, and as multiple, active discrete phases of dune field and deflation plain couplets in temperate to tropical environments. Active dune fields tend to be singular entities on coasts with low to moderate sediment supply. Landscape complexity and vegetation richness and diversity increases as dune fields evolve from simple active sheets and dunes to single and multiple deflation plains and basins, precipitation ridges, nebkha fields and a host of other dune types associated with vegetation (e.g. trailing ridges, slacks, remnant knobs, gegenwalle ridges and dune track ridges, ‘tree islands' and ‘bush pockets'). Three principal scenarios of transgressive dune sheet and dune field development are discussed, including dune sheets or dune fields evolving directly from the backshore, development following foredune and/or dune field erosion, and development from the breakdown or merging of parabolic dunes. Various stages of evolution are outlined for each scenario. Knowledge of evolutionary patterns and stages in coastal dune fields is very limited and caution is urged in attempts to reverse, change and/or modify dune fields to ‘restore' some perceived loss of ecosystem or dune functioning.

  6. Conceptual models of the evolution of transgressive dune field systems

    NASA Astrophysics Data System (ADS)

    Hesp, Patrick A.

    2013-10-01

    This paper examines the evolutionary paths of some transgressive dune fields that have formed on different coasts of the world, and presents some initial conceptual models of system dynamics for transgressive dune sheets and dune fields. Various evolutionary pathways are conceptualized based on a visual examination of dune fields from around the world. On coasts with high sediment supply, dune sheets and dune fields tend to accumulate as large scale barrier systems with little colonization of vegetation in arid-hyper to arid climate regimes, and as multiple, active discrete phases of dune field and deflation plain couplets in temperate to tropical environments. Active dune fields tend to be singular entities on coasts with low to moderate sediment supply. Landscape complexity and vegetation richness and diversity increases as dune fields evolve from simple active sheets and dunes to single and multiple deflation plains and basins, precipitation ridges, nebkha fields and a host of other dune types associated with vegetation (e.g. trailing ridges, slacks, remnant knobs, gegenwalle ridges and dune track ridges, 'tree islands' and 'bush pockets'). Three principal scenarios of transgressive dune sheet and dune field development are discussed, including dune sheets or dune fields evolving directly from the backshore, development following foredune and/or dune field erosion, and development from the breakdown or merging of parabolic dunes. Various stages of evolution are outlined for each scenario. Knowledge of evolutionary patterns and stages in coastal dune fields is very limited and caution is urged in attempts to reverse, change and/or modify dune fields to 'restore' some perceived loss of ecosystem or dune functioning.

  7. Mars Global Digital Dune Database; MC-1

    USGS Publications Warehouse

    Hayward, R.K.; Fenton, L.K.; Tanaka, K.L.; Titus, T.N.; Colaprete, A.; Christensen, P.R.

    2010-01-01

    The Mars Global Digital Dune Database presents data and describes the methodology used in creating the global database of moderate- to large-size dune fields on Mars. The database is being released in a series of U.S. Geological Survey (USGS) Open-File Reports. The first release (Hayward and others, 2007) included dune fields from 65 degrees N to 65 degrees S (http://pubs.usgs.gov/of/2007/1158/). The current release encompasses ~ 845,000 km2 of mapped dune fields from 65 degrees N to 90 degrees N latitude. Dune fields between 65 degrees S and 90 degrees S will be released in a future USGS Open-File Report. Although we have attempted to include all dune fields, some have likely been excluded for two reasons: (1) incomplete THEMIS IR (daytime) coverage may have caused us to exclude some moderate- to large-size dune fields or (2) resolution of THEMIS IR coverage (100m/pixel) certainly caused us to exclude smaller dune fields. The smallest dune fields in the database are ~ 1 km2 in area. While the moderate to large dune fields are likely to constitute the largest compilation of sediment on the planet, smaller stores of sediment of dunes are likely to be found elsewhere via higher resolution data. Thus, it should be noted that our database excludes all small dune fields and some moderate to large dune fields as well. Therefore, the absence of mapped dune fields does not mean that such dune fields do not exist and is not intended to imply a lack of saltating sand in other areas. Where availability and quality of THEMIS visible (VIS), Mars Orbiter Camera narrow angle (MOC NA), or Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) images allowed, we classified dunes and included some dune slipface measurements, which were derived from gross dune morphology and represent the prevailing wind direction at the last time of significant dune modification. It was beyond the scope of this report to look at the detail needed to discern subtle dune modification. It was also beyond the scope of this report to measure all slipfaces. We attempted to include enough slipface measurements to represent the general circulation (as implied by gross dune morphology) and to give a sense of the complex nature of aeolian activity on Mars. The absence of slipface measurements in a given direction should not be taken as evidence that winds in that direction did not occur. When a dune field was located within a crater, the azimuth from crater centroid to dune field centroid was calculated, as another possible indicator of wind direction. Output from a general circulation model (GCM) is also included. In addition to polygons locating dune fields, the database includes THEMIS visible (VIS) and Mars Orbiter Camera Narrow Angle (MOC NA) images that were used to build the database. The database is presented in a variety of formats. It is presented as an ArcReader project which can be opened using the free ArcReader software. The latest version of ArcReader can be downloaded at http://www.esri.com/software/arcgis/arcreader/download.html. The database is also presented in an ArcMap project. The ArcMap project allows fuller use of the data, but requires ESRI ArcMap(Registered) software. A fuller description of the projects can be found in the NP_Dunes_ReadMe file (NP_Dunes_ReadMe folder_ and the NP_Dunes_ReadMe_GIS file (NP_Documentation folder). For users who prefer to create their own projects, the data are available in ESRI shapefile and geodatabase formats, as well as the open Geography Markup Language (GML) format. A printable map of the dunes and craters in the database is available as a Portable Document Format (PDF) document. The map is also included as a JPEG file. (NP_Documentation folder) Documentation files are available in PDF and ASCII (.txt) files. Tables are available in both Excel and ASCII (.txt)

  8. Winds drive dune movement on Mars

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2012-01-01

    Sand dunes, a common feature on the surface of Mars, can provide a record of recent and past changes. Some dunes near Mars's polar areas have recently been observed to change due to carbon dioxide ice sublimation, but it has not been confirmed whether dunes are still active all over Mars. Winds contribute to dune movement on Earth, but wind tunnel and atmospheric computer simulations have suggested that strong winds would be rare in the current Martian atmosphere. In a new study, Silvestro et al. observe recent dune movement in Mars's tropical regions, which are not affected by seasonal changes in carbon dioxide frost. Focusing on the Arabia Terra and Meridiani regions on Mars, the researchers analyzed images from the High Resolution Science Experiment (HiRISE) camera on board the Mars Reconnaissance Orbiter as well as other sources of data. They measured migration rates of two groups of ripples in the sand in a dune field in Meridiani Planum and found that dunes advanced about 0.4-1 meter in a Martian year.

  9. Response of Terrestrial Arthropod Assemblages to Coastal Dune Restoration

    Microsoft Academic Search

    John W. Doudna; Edward F. Connor

    2012-01-01

    To restore historical dune vegetation, substantial effort has been made to remove the invasive plant species, European beach grass (Ammophila arenaria), from coastal dunes of California, USA. However, little effort has been made to examine the response of terrestrial arthropod assemblages to coastal dune restoration. We sampled terrestrial arthropods at 6 dune restoration sites to determine the response of the

  10. Coastal dune stability: The effect of meteorological conditions and vegetation

    Microsoft Academic Search

    B. G. Watt

    1977-01-01

    Quantitative investigations and research conducted along the north coast of New South Wales, Australia are evaluated with respect to coastal processes, coastal alignment, meteorological data, dune dimensions, dune vegetative cover, development on the dunal area and dune management. The data available covered an assessment of the extent of dune instabilities, an assessment of long term coastline movements, a study of

  11. Three-dimensional mapping of airflow over dunes

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2013-05-01

    Similar to the way a river, flowing across Earth's surface, influences sediment transport and shaping of the landscape, coastal winds, which flow over dunes, affect how the dune shapes evolve and how sand is transported along the coast. Wind flow over dunes has been extensively studied, but in most cases, that research has been two-dimensional and focused on straight dunes with smooth slopes and no vegetation or other features that might affect how airflow separates at the crest of the dune.

  12. Membranous lupus nephritis with antineutrophil cytoplasmic antibody-associated segmental necrotizing and crescentic glomerulonephritis

    Microsoft Academic Search

    Susan Marshall; Robert Dressler; Vivette D'Agati

    1997-01-01

    Focal segmental necrotizing and crescentic lupus nephritis accompanied by perinuclear antineutrophil cytoplasmic antibody (P-ANCA) seropositivity is an unusual occurrence. We report the first biopsy-documented cases of membranous lupus nephritis class V with associated “pauci-immune” segmental necrotizing glomerulonephritis and P-ANCA seropositivity. The absence of subendothelial electron-dense deposits favored a manifestation of superimposed ANCA-associated glomerulonephritis rather than class III lupus nephritis. The

  13. 76 FR 7844 - Environmental Impacts Statements; Notice of Availability

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-11

    ...16,500 Acres of Public Land to the Westside Irrigation District, Big Horn and Washakie Counties, WY...No. 20100444, Final EIS, BLM, NV, Tonopah Solar Energy Crescent Dunes Solar Energy Project, a 7,680-Acre...

  14. Geometric aeolian dune crest migration model

    NASA Astrophysics Data System (ADS)

    Swanson, T.; Mohrig, D. C.; Kocurek, G.; Pedersen, A.

    2012-12-01

    We present a geometric aeolian dune crest model that provides a predictive linkage between local lee face sediment deposition and wholesale landform change. The model is driven using an initial condition of 3D dune crest data obtained from a time series of airborne LIDAR surveys of White Sands, NM, and wind observations from nearby Holloman AFB. Transient dune migration is modeled by volume filling of a simple theoretical dune geometry with sediment flux derived using shear velocity dependent transport (Bagnold, 1941) modified by a new incidence angle dependent lee face sediment deposition function styled after Rubin and Hunter (1985). Model calibration is achieved using an azimuthal wind direction correction and threshold values for shear velocity dependent sediment transport. Agreement between observations and model results are presented using a l2 norm representing a global error estimate.

  15. Priorities for Future Research on Planetary Dunes

    NASA Astrophysics Data System (ADS)

    Titus, Timothy N.; Lancaster, Nick; Hayward, Rose; Fenton, Lori; Bourke, Mary

    2008-11-01

    Planetary Dunes Workshop: A Record of Climate Change; Alamogordo, New Mexico, 28 April to 2 May 2008; Landforms and deposits created by the dynamic interactions between granular material and airflow (eolian processes) occur on several planetary bodies, including Earth, Mars, Titan, and Venus. To address many of the outstanding questions within planetary dune research, a workshop was organized by the U.S. Geological Survey, the Planetary Science Institute, the Desert Research Institute, and the Search for Extraterrestrial Intelligence Institute and was sponsored by the Lunar and Planetary Institute and the Jet Propulsion Laboratory. The workshop brought together researchers from diverse backgrounds, ranging from image analysis and modeling to terrestrial analog studies. The group of approximately 45 international researchers had intense discussions in an attempt to identify the most promising approaches to understanding planetary dune systems. On the basis of these discussions, the group identified the following 10 priorities for future planetary dune research.

  16. Invasive plants on disturbed Korean sand dunes

    NASA Astrophysics Data System (ADS)

    Kim, Kee Dae

    2005-01-01

    The sand dunes in coastal regions of South Korea are important ecosystems because of their small size, the rare species found in this habitat, and the beautiful landscapes they create. This study investigated the current vegetative status of sand dunes on three representative coasts of the Korean peninsula, and on the coasts of Cheju Island, and assessed the conditions caused by invasive plants. The relationships between the degree of invasion and 14 environmental variables were studied. Plots of sand dunes along line transects perpendicular to the coastal lines were established to estimate vegetative species coverage. TWINSPAN (Two-Way Indicator Species Analysis), CCA (Canonical Correspondence Analysis), and DCCA (Detrended Canonical Correspondence Analysis) were performed to classify communities on sand dunes and assess species composition variation. Carex kobomugi, Elymus mollis, and Vitex rotundifolia were found to be the dominant species plotted on the east, the west, and the peripheral coasts of Cheju Island, respectively. Vegetation on the south coast was totally extinct. The 19 communities, including representative C. kobomugi, C. kobomugi- Ixeris repens, C. kobomugi- Oenothera biennis, E. mollis, Lolium multiflorum- Calystegia soldanella, and V. rotundifolia- C. kobomugi, were all classified according to TWINSPAN. Oenothera biennis and L. multiflorum were exotics observed within these native communities. CCA showed that invasive native and exotic species distribution was segregated significantly, according to disturbance level, exotic species number, gravel, sand and silt contents, as well as vegetation size. It further revealed that human disturbance can strongly favor the settlement of invasive and exotic species. Restoration options to reduce exotic plants in the South Korean sand dune areas were found to be the introduction of native plant species from one sand dune into other sand dune areas, prohibition of building and the introduction of exotic soils, and conservation of surrounding sand dune areas.

  17. Northern polar dunes: a spring activity analog to that seen in southern polar terrains

    NASA Astrophysics Data System (ADS)

    Portyankina, Ganna; Thomas, Nicolas; Pommerol, Antoine; Aye, Klaus-Michael

    The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Or-biter (MRO) is presently (February 2010) observing its second northern spring on Mars. Com-plimentary spectral information from CRISM is available to gain insight into the composition and physical state of the surface. In the north polar areas, there are active regions. Here, dark dunes extend almost circumferen-tially around the permanent polar cap. This area exhibits phenomena similar to those observed in south polar areas in southern spring. Among these phenomena are cracks in a translucent ice layer which are considered to be manifestations of ice damage by increasing pressure at the interface between the ice layer and substrate underlying it [1]. Bright and dark fans, attributed to cold jet activity, are also observed on top of dunes [2]. The presence of these features indi-cates that dunes are covered by a conformal ice layer and that this layer is at least partially transparent to solar radiation. CO2 ice sublimation and processes connected to it appear to produce a variety of observable features. Yet another distinctive feature observed in this area (and rarely present in the south) is the presence of dark slope streaks on dunes. They originate from the crests of dunes and run down following the gravitational potential. They lengthen as the season progresses. Their origin has been discussed to be possible liquid brine flows [3, 4]. In the present work we report on indications that these slope streaks are instead dry mass wasting process. Due to geometry of solar illumination at local latitude the energy input on the crest is higher than in the valley between dunes. The ice cover thins most quickly in areas closest to the crest. In addition, applying stress distribution calculations to the conformal ice layer on realistic dune geometry, we show that the crest of the dune is the weakest point for the ice bending stress. The rupture of the ice layer therefore happens close to the dune's crest on the slip face and is followed by the escape of dry dune material from its top layer downslope. Streaks are overlaid on the ice layer and produce the observed contrast changes. Seasonal lengthening of the streaks can be attributed to the repeatability of this process when more and more dune material gets freed from the ice layer. An enhancement of this effect can occur if the rupture of the ice layer gives rise to an escape of gas trapped under it. The gas pressure, in this case, is produced by the same process that is proposed for araneiform formation in south polar areas [5]. Gas movement mobilises fine dune material and transports it towards the slip slope whereupon it runs down the slope. The described model does not involve liquid flows but is nonetheless fully consistent with HiRISE observations of this phenomenon. [1] G. Portyankina et al., 2010, 41st Lunar and Planetary Science Conference, Abstract #2671 [2] C. Hansen et al., 2010, 41st Lunar and Planetary Science Conference, Abstract #2029 [3] D. Moehlmann, 2008, Icarus, 195:131-139. [4] A. Kereszturi et al., 2009, Icarus 201:492-503. [5] H. Kieffer, 2007, JGR, 112.

  18. A bibliography of dunes: Earth, Mars, and Venus

    NASA Technical Reports Server (NTRS)

    Lancaster, N.

    1988-01-01

    Dunes are important depositional landforms and sedimentary environments on Earth and Mars, and may be important on Venus. The similarity of dune forms on Earth and Mars, together with the dynamic similarity of aeolian processes on the terrestrial planets indicates that it is appropriate to interpret dune forms and processes on Mars and Venus by using analog studies. However, the literature on dune studies is large and scattered. The aim of this bibliography is to assist investigators by providing a literature resource on techniques which have proved successful in elucidating dune characteristics and processes on Earth, Mars, and Venus. This bibliography documents the many investigations of dunes undertaken in the last century. It concentrates on studies of inland dunes in both hot and cold desert regions on Earth and includes investigations of coastal dunes only if they discuss matters of general significance for dune sediments, processes, or morphology.

  19. Modeling emergent large-scale structures of barchan dune fields

    NASA Astrophysics Data System (ADS)

    Worman, S. L.; Murray, A.; Littlewood, R. C.; Andreotti, B.; Claudin, P.

    2013-12-01

    In nature, barchan dunes typically exist as members of larger fields that display striking, enigmatic structures that cannot be readily explained by examining the dynamics at the scale of single dunes, or by appealing to patterns in external forcing. To explore the possibility that observed structures emerge spontaneously as a collective result of many dunes interacting with each other, we built a numerical model that treats barchans as discrete entities that interact with one another according to simplified rules derived from theoretical and numerical work, and from field observations: Dunes exchange sand through the fluxes that leak from the downwind side of each dune and are captured on their upstream sides; when dunes become sufficiently large, small dunes are born on their downwind sides ('calving'); and when dunes collide directly enough, they merge. Results show that these relatively simple interactions provide potential explanations for a range of field-scale phenomena including isolated patches of dunes and heterogeneous arrangements of similarly sized dunes in denser fields. The results also suggest that (1) dune field characteristics depend on the sand flux fed into the upwind boundary, although (2) moving downwind, the system approaches a common attracting state in which the memory of the upwind conditions vanishes. This work supports the hypothesis that calving exerts a first order control on field-scale phenomena; it prevents individual dunes from growing without bound, as single-dune analyses suggest, and allows the formation of roughly realistic, persistent dune field patterns.

  20. Predictability of dune activity in real dune fields under unidirectional wind regimes

    NASA Astrophysics Data System (ADS)

    Barchyn, Thomas E.; Hugenholtz, Chris H.

    2015-02-01

    We present an analysis of 10 dune fields to test a model-derived hypothesis of dune field activity. The hypothesis suggests that a quantifiable threshold exists for stabilization in unidirectional wind regimes: active dunes have slipface deposition rates that exceed the vegetation deposition tolerance, and stabilizing dunes have the opposite. We quantified aeolian sand flux, slipface geometry, and vegetation deposition tolerance to directly test the hypothesis at four dune fields (Bigstick, White Sands Stable, White Sands Active, and Cape Cod). We indirectly tested the hypothesis at six additional dune fields with limited vegetation data (Hanford, Año Nuevo, Skagen Odde, Salton Sea, Oceano Stable, and Oceano Active, "inverse calculation sites"). We used digital topographic data and estimates of aeolian sand flux to approximate the slipface deposition rates prior to stabilization. Results revealed a distinct, quantifiable, and consistent pattern despite diverse environmental conditions: the modal peak of prestabilization slipface deposition rates was 80% of the vegetation deposition tolerance at stabilized or stabilizing dune fields. Results from inverse calculation sites indicate deposition rates at stabilized sites were near a hypothesized maximum vegetation deposition tolerance (1 m a-1), and active sites had slipface deposition rates much higher. Overall, these results confirm the hypothesis and provide evidence of a globally applicable, simple, and previously unidentified predictor for the dynamics of vegetation cover in dune fields under unidirectional wind regimes.

  1. Monitoring sand dune stabilization along the coastal dunes of Ashdod-Nizanim, Israel, 1945–1999

    Microsoft Academic Search

    N. Levin; E. Ben-Dor

    2004-01-01

    Temporal changes in the stabilization process along the coastal dunes of Israel were assessed using a series of 23 aerial photographs taken over the period 1944–1999. The stabilization rate was then quantified using a specially developed method for the calculation of sand dune movement and by the calibration of the gray-scale images into vegetation cover maps. An episodic reactivation of

  2. White Sands Dune Field, New Mexico: Age, dune dynamics and recent accumulations

    Microsoft Academic Search

    Gary Kocurek; Mary Carr; Ryan Ewing; Karen G. Havholm; Y. C. Nagar; A. K. Singhvi

    2006-01-01

    The White Sands Dune Field, situated within the Tularosa Basin in southern New Mexico, is thought to have been largely derived by a stepwise, progressive deflation of Pleistocene Lake Otero strata with the onset of regional aridity. Optically stimulated luminescence (OSL) dating of samples from a core that penetrated the gypsum accumulation of the dune field confirm a time of

  3. Bucillamine-Induced Membranous Nephropathy with Crescent Formation in a Patient with Rheumatoid Arthritis: Case Report and Literature Review

    PubMed Central

    Manabe, Shun; Banno, Mayuko; Nakano, Marie; Fujii, Teruhiro; Fujiwara, Michio; Kita, Yasuhiko; Nitta, Kosaku; Hatano, Michiyasu

    2015-01-01

    Bucillamine is a disease-modifying antirheumatic drug that is structurally similar to D-penicillamine. The major renal side effect of bucillamine and D-penicillamine is proteinuria caused by membranous nephropathy (MN). In addition to MN, combined crescent formation has been occasionally reported in D-penicillamine-induced MN, while crescent formation has been rarely reported in bucillamine-treated cases. Here, we describe a 76-year-old female who presented with nephrotic syndrome and rapidly progressive glomerulonephritis. She was receiving bucillamine as initial treatment for recently diagnosed rheumatoid arthritis, and renal biopsy showed MN with crescent formation. To the best of our knowledge, this is the first report of bucillamine-induced MN with crescent formation in the English literature. PMID:25849672

  4. Dunes On Titan: Comparison Of The Fensal And Belet Dune Regions Using Multiple Datasets

    NASA Astrophysics Data System (ADS)

    Le Gall, Alice; Janssen, M. A.; Wye, L. C.; Hayes, A. G.; Lorenz, R. D.; Radebaugh, J.; Stiles, B.; Cassini RADAR Team

    2010-10-01

    Titan's equatorial belt hosts large expanses of longitudinal dunes. As the Cassini mission continues, more of them are unveiled by the microwave RADAR, both in the active and passive modes and with an increasing number of viewing geometries. These observations have revealed some variations among dune regions. In particular, we find that the Belet and Fensal dune fields differ in terms of radar albedo and thermal emission. In this paper, we combine different datasets (SAR, radiometry, altimetry, scatterometry and SAR-derived topography) and compare them to an electromagnetic model in order to constrain the compositional and physical properties of the Belet and Fensal dunes. Differences between Fensal and Belet are well explained by various degrees of exposure of Titan's icy crust in the interdune regions (the troughs between the dunes). We find that a significant fraction of the Fensal interdunes must either be clear of sand, thus representing the dune substrate, or covered by icy gravels. This is consistent with VIMS spectra that show an enrichment in water ice in Fensal interdunes (Barnes et al., 2008). Furthermore, in many places in Fensal, dunes remain quite bright on SAR images suggesting that they are thin enough to allow waves to probe the substrate. Both interdune brightness and dune thinning point to the lack of available sediment supply in Fensal. In contrast, sand-sized particles seem abundant at Belet's location where the sand sheet is so thick that even the interdune flats appear radar-dark. The difference in sand supply between Fensal and Belet may be due to different wind regime and/or ground humidity. It may also be related to their respective emplacement: Belet is laying in a deep depression and Fensal dunes encroach on Sinlap's fresh water-ice ejecta blanket. The paper will discuss further the origin of the regional variations among Titan dunes.

  5. [Temporal crescent syndrome. Report of a case and review of the literature].

    PubMed

    Mery, Victoria; Mellado, Patricio; Valenzuela, Raúl; Luco, Cristián; Huete, Isidro

    2004-12-01

    The temporal crescent syndrome or half-moon syndrome is a rare mono ocular retrochiasmatic visual field defect that can be correlated to a lesion along the contralateral parieto-occipital sulcus. This field defect may be missed in automated perimetry. We report a 45 year old man, consulting for sudden loss of the peripheral temporal field in his right eye. The magnetic resonance imaging and the spectroscopy studies confirmed an ischemic lesion on the left anterior occipital cortex. Control imaging studies six months later did not show changes in the lesion. PMID:15743165

  6. Relapsing proliferative glomerulonephritis with monoclonal IgG deposits showing circumferential crescentic glomerulonephritis

    PubMed Central

    Oshio, Mai; Fujii, Takuma; Kusaura, Takashi; Nagahama, Kiyotaka

    2013-01-01

    Several types of glomerulonephritis associated with dysproteinemia, such as AL-amyloidosis, light- and heavy-chain deposition disease, and type 1 cryoglobulinemic glomerulopathy, demonstrate monoclonal immunoglobulin deposition. Progressive glomerulonephritis with monoclonal IgG deposits (PGNMID) is also known to feature monoclonal glomerular deposits, but most of these cases occur without underlying disease. We here report a case of recurrent PGNMID that developed as diffuse cellular crescentic glomerulonephritis 8 years after an initial diagnosis of membranoproliferative glomerulonephritis (MPGN). Determination of the monoclonality of the deposited immunoglobulin is vital to make the correct diagnosis and enable an early administration of aggressive immunosuppressive therapy.

  7. Recurrent or de novo IgA nephropathy with crescent formation after renal transplantation.

    PubMed

    Tang, Zheng; Ji, Shu-Ming; Chen, Dong-Rui; Wen, Ji-Qiu; Chen, Jin-Song; Liu, Zhi-Hong; Li, Lei-Shi

    2008-01-01

    IgA nephropathy is the most common glomerular disease in China, accounting for 38.8% of primary glomerular disease. It has been reported that 20.8% patients of IgA nephropathy had a different degree of crescent formation. From January 1995 to December 2004, 1000 patients had undergone cadaveric renal transplantation, and 1742 allograft renal biopsies were reviewed in the Department of Nephrology at Jinling Hospital, Nanjing University. Among them, 18 cases were found with crescent formation, in which 10 patients were diagnosed as recurrent or de novo IgA nephropathy because their immunofluorescence showed strong IgA deposition in mesangial area and capillary. The initial treatment protocol was CsA+Azp+Pred, except in two cases of CsA+MMF+Pred. There were 8 males and 2 females, with ages from 25 to 69 (mean of 37.1) years old. All of them showed progressive renal dysfunction with increasing level of serum creatinine ranged from 1.48 to 6.25 mg/dL. Seven cases presented edema with an increasing level of proteinuria (1.36 to 3.58 g/24hr), and nine cases presented with hematuria ranging from 50 to 1250 x 10(4)/mL (one showed gross hematuria). In pathological examinations, they showed mesangial proliferation and matrix expansion with 10% to 66.7% crescents (mean of 37.5%) in their allograft renal biopsy's samples. All patients changed their immunosuppressive regimens; however, nine of them eventually advanced to ESRD and returned to hemodialysis after 6 to 36 months. Two cases received second renal transplantation after six months to five years, and one kept stable renal function with 2.5 mg/dL of serum creatinine after three years of follow-up. IgA nephropathy with crescentic formation was not rare in renal allografts or native glomerulonephritis in Chinese patients. These patients showed rapidly progressive renal dysfunction, and most of them lost graft function and needed hemodialysis therapy. PMID:18661411

  8. Mobile dunes and eroding salt marshes

    NASA Astrophysics Data System (ADS)

    Neuhaus, R.

    1994-06-01

    The paper deals with general outlines of salt marsh and dune vegetation in the Ellenbogen and Listland area on Sylt (Schleswig-Holstein, FRG). The composition of current salt marsh vegetation is considered to be mainly the result of a long-lasting process of tidal inundation, grazing, and a permanent influence of groundwater seepage from the surrounding dunes. The lower salt marsh communities have shown constancy for 67 years, due to the effect of heavy grazing. The mid-upper salt marsh communities demonstrated a succession from a Puccinellia maritima-dominated community of the lower marsh to a Juncus gerardii-dominated community of the mid-upper salt marsh, which may be due to the transport of sand — over a short time — on the surface of the marsh. The area covered by plant communities of annuals below Mean High Water (MHW) seemed to diminish. Salt marsh soils, especially of the mid-upper marsh, indicate sandy layers resulting from sand drift of the dunes. Dry and wet successional series of the dunes in the Listland/Ellenbogen area both show grassy stages shifting to dwarf shrubs as final stages. White primary dunes can only be found on the accreting shoreline of the Ellenbogen, which is also grazed by sheep; vegetation cover therefore remains dominated by grasses, mosses and lichens. Three mobile dunes (as the most prominent features of this landscape) have been left unaffected by seeding and planting by local authorities. Grazing is considered to be an inadequate tool in nature conservation as long as natural processes are to prevail in the landscape as major determinants.

  9. Sand dune movement in the Victoria Valley, Antarctica

    Microsoft Academic Search

    Mary C. Bourke; Ryan C. Ewing; David Finnegan; Hamish A. McGowan

    2009-01-01

    We use vertical aerial photographs and LiDAR topographic survey data to estimate dune migration rates in the Victoria Valley dunefield, Antarctica, between 1961 and 2001. Results confirm that the dunes migrated an average of 1.5 m\\/year. These values are consistent with other estimates of dune migration from cold climate deserts and are significantly lower than estimates from warm deserts. Dune migration

  10. Lateral migration of linear dunes in the Strzelecki Desert, Australia

    USGS Publications Warehouse

    Rubin, D.M.

    1990-01-01

    Preferential accumulation of sand on east-facing flanks indicates that the dunes migrated eastward several metres during the Holocene. Moreover, the west-facing flanks of some dunes have experienced a minimum of tens of metres of erosion. This asymmetric erosion and deposition were caused by dune obliquity and lateral migration that may have begun as early as the Pleistocene. Dunes in the Strzelecki Desert and in the adjacent Simpson Desert display a variety of grossly different internal structures. -from Author

  11. Mars global digital dune database and initial science results

    USGS Publications Warehouse

    Hayward, R.K.; Mullins, K.F.; Fenton, L.K.; Hare, T.M.; Titus, T.N.; Bourke, M.C.; Colaprete, A.; Christensen, P.R.

    2007-01-01

    A new Mars Global Digital Dune Database (MGD3) constructed using Thermal Emission Imaging System (THEMIS) infrared (IR) images provides a comprehensive and quantitative view of the geographic distribution of moderate- to large-size dune fields (area >1 kM2) that will help researchers to understand global climatic and sedimentary processes that have shaped the surface of Mars. MGD3 extends from 65??N to 65??S latitude and includes ???550 dune fields, covering ???70,000 km2, with an estimated total volume of ???3,600 km3. This area, when combined with polar dune estimates, suggests moderate- to large-size dune field coverage on Mars may total ???800,000 km2, ???6 times less than the total areal estimate of ???5,000,000 km2 for terrestrial dunes. Where availability and quality of THEMIS visible (VIS) or Mars Orbiter Camera. narrow-angle (MOC NA) images allow, we classify dunes and include dune slipface measurements, which are derived from gross dune morphology and represent the prevailing wind direction at the last time of significant dune modification. For dunes located within craters, the azimuth from crater centroid to dune field centroid (referred to as dune centroid azimuth) is calculated and can provide an accurate method for tracking dune migration within smooth-floored craters. These indicators of wind direction are compared to output from a general circulation model (GCM). Dune centroid azimuth values generally correlate to regional wind patterns. Slipface orientations are less well correlated, suggesting that local topographic effects may play a larger role in dune orientation than regional winds. Copyright 2007 by the American Geophysical Union.

  12. Recovery of Danish coastal dune vegetation after a wildfire

    Microsoft Academic Search

    2001-01-01

    The initial recovery of vegetation after a wildfire in a coastal dune area in NW Jutland, Denmark, was studied over a 5-yr\\u000a period by means of permanent plots representing various dune communities along a topographical gradient.\\u000a \\u000a The impact of the fire varied with the position of the plots. Fens and south-facing dunes were little affected while dune\\u000a heath plots were

  13. Spatially resolved electron energy loss spectroscopy of crescent-shaped plasmonic antennas.

    PubMed

    K?ápek, V; Koh, A L; B?ínek, L; Hrto?, M; Tomanec, O; Kalousek, R; Maier, S A; Šikola, T

    2015-05-01

    We present a study of the optical properties of gold crescent-shaped antennas by means of electron energy loss spectroscopy. These structures exhibit particularly large field enhancement near their sharp features, support two non-degenerate dipolar (i.e., optically active) localised surface plasmon resonances, and are widely tunable by a choice of their shape and dimensions. Depending on the volume and shape, we resolved up to four plasmon resonances in metallic structures under study in the energy range of 0.8 - 2.4 eV: two dipolar and quadrupolar mode and a multimodal assembly. The boundary-element-method calculations reproduced the observed spectra and helped to identify the character of the resonances. The two lowest modes are of particular importance owing to their dipolar nature. Remarkably, they are both concentrated near the tips of the crescent, spectrally well resolved and their energies can be tuned between 0.8 - 1.5 eV and 1.2 - 2.0 eV, respectively. As the lower spectral range covers the telecommunication wavelengths 1.30 and 1.55 ?m, we envisage the possible use of such nanostructures in infrared communication technology. PMID:25969276

  14. Lutheran/basal cell adhesion molecule accelerates progression of crescentic glomerulonephritis in mice.

    PubMed

    Huang, Jin; Filipe, Anne; Rahuel, Cécile; Bonnin, Philippe; Mesnard, Laurent; Guérin, Coralie; Wang, Yu; Le Van Kim, Caroline; Colin, Yves; Tharaux, Pierre-Louis

    2014-05-01

    Migration of circulating leukocytes from the vasculature into the surrounding tissue is an important component of the inflammatory response. Among the cell surface molecules identified as contributing to leukocyte extravasation is VCAM-1, expressed on activated vascular endothelium, which participates in all stages of leukocyte-endothelial interaction by binding to leukocyte surface expressed integrin VLA-4. However, not all VLA-4-mediated events can be linked to VCAM-1. A novel interaction between VLA-4 and endothelial Lutheran (Lu) blood group antigens and basal cell adhesion molecule (BCAM) proteins has been recently shown, suggesting that Lu/BCAM may have a role in leukocyte recruitments in inflamed tissues. Here, we assessed the participation of Lu/BCAM in the immunopathogenesis of crescentic glomerulonephritis. High expression of Lu/BCAM in glomeruli of mice with rapidly progressive glomerulonephritis suggests a potential role for the local expression of Lu/BCAM in nephritogenic recruitment of leukocytes. Genetic deficiency of Lu/BCAM attenuated glomerular accumulation of T cells and macrophages, crescent formation, and proteinuria, correlating with reduced fibrin and platelet deposition in glomeruli. Furthermore, we found a pro-adhesive interaction between human monocyte ?4?1 integrin and Lu/BCAM proteins. Thus, Lu/BCAM may have a critical role in facilitating the accumulation of monocytes and macrophages, thereby exacerbating renal injury. PMID:24429403

  15. Lutheran/basal cell adhesion molecule accelerates progression of crescentic glomerulonephritis in mice

    PubMed Central

    Huang, Jin; Filipe, Anne; Rahuel, Cécile; Bonnin, Philippe; Mesnard, Laurent; Guérin, Coralie; Wang, Yu; Le Van Kim, Caroline; Colin, Yves; Tharaux, Pierre-Louis

    2014-01-01

    Migration of circulating leukocytes from the vasculature into the surrounding tissue is an important component of the inflammatory response. Among the cell surface molecules identified as contributing to leukocyte extravasation is VCAM-1, expressed on activated vascular endothelium, which participates in all stages of leukocyte–endothelial interaction by binding to leukocyte surface expressed integrin VLA-4. However, not all VLA-4-mediated events can be linked to VCAM-1. A novel interaction between VLA-4 and endothelial Lutheran (Lu) blood group antigens and basal cell adhesion molecule (BCAM) proteins has been recently shown, suggesting that Lu/BCAM may have a role in leukocyte recruitments in inflamed tissues. Here, we assessed the participation of Lu/BCAM in the immunopathogenesis of crescentic glomerulonephritis. High expression of Lu/BCAM in glomeruli of mice with rapidly progressive glomerulonephritis suggests a potential role for the local expression of Lu/BCAM in nephritogenic recruitment of leukocytes. Genetic deficiency of Lu/BCAM attenuated glomerular accumulation of T cells and macrophages, crescent formation, and proteinuria, correlating with reduced fibrin and platelet deposition in glomeruli. Furthermore, we found a pro-adhesive interaction between human monocyte ?4?1 integrin and Lu/BCAM proteins. Thus, Lu/BCAM may have a critical role in facilitating the accumulation of monocytes and macrophages, thereby exacerbating renal injury. PMID:24429403

  16. Were Fertile Crescent crop progenitors higher yielding than other wild species that were never domesticated?

    PubMed

    Preece, Catherine; Livarda, Alexandra; Wallace, Michael; Martin, Gemma; Charles, Michael; Christin, Pascal-Antoine; Jones, Glynis; Rees, Mark; Osborne, Colin P

    2015-08-01

    During the origin of agriculture in the Fertile Crescent, the broad spectrum of wild plant species exploited by hunter-gatherers narrowed dramatically. The mechanisms responsible for this specialization and the associated domestication of plants are intensely debated. We investigated why some species were domesticated rather than others, and which traits they shared. We tested whether the progenitors of cereal and pulse crops, grown individually, produced a higher yield and less chaff than other wild grasses and legumes, thereby maximizing the return per seed planted and minimizing processing time. We compared harvest traits of species originating from the Fertile Crescent, including those for which there is archaeological evidence of deliberate collection. Unexpectedly, wild crop progenitors in both families had neither higher grain yield nor, in grasses, less chaff, although they did have larger seeds. Moreover, small-seeded grasses actually returned a higher yield relative to the mass of seeds sown. However, cereal progenitors had threefold fewer seeds per plant, representing a major difference in how seeds are packaged on plants. These data suggest that there was no intrinsic yield advantage to adopting large-seeded progenitor species as crops. Explaining why Neolithic agriculture was founded on these species, therefore, remains an important unresolved challenge. PMID:25758766

  17. Membranous nephropathy with crescents in a patient with Hashimoto's thyroiditis: a case report.

    PubMed

    Thajudeen, Bijin; John, Santhosh G; Ossai, Nduka-Obi; Riaz, Irbaz B; Bracamonte, Erika; Sussman, Amy N

    2014-08-01

    Membranous nephropathy is a common cause of nephrotic syndrome in adults. It usually occurs secondary to underlying disease processes such as autoimmune disorders, malignancy, infection, and drugs. The presentation of nephrotic syndrome with concomitant precipitous decline in renal function warrants investigation of a coexistent disorder.We report the case of a 30-year-old male who presented with symptoms and signs of hypothyroidism.A diagnosis of Hashimoto's thyroiditis was contemplated based on the presence of high serum levels of antithyroglobulin and antithyroid peroxidase antibodies. Upon initiation of treatment with levothyroxine, patient symptomatology improved; however, the laboratory studies demonstrated continued elevated creatinine, hematuria, and proteinuria, which had not been addressed. Two months following treatment initiation, he had progressive deterioration in renal function and proteinuria. A renal biopsy revealed coexistent necrotizing and crescentic glomerulonephritis and membranous nephropathy.The final diagnosis was necrotizing, crescentic glomerulonephritis with superimposed membranous nephropathy likely secondary to Hashimoto's thyrodiitis.Induction treatment with oral cyclophosphamide and prednisone was started.At the end of 6 months of treatment, there was improvement in renal function and proteinuria and maintenance treatment with azathioprine and low-dose prednisone was initiated. This case highlights the importance of precise and detailed evaluation of patients with autoimmune diseases such as Hashimoto's thyroiditis particularly in the presence of active urine sediment. Proper evaluation and diagnosis of such patients has implications on the prognosis and response to treatment. PMID:25121358

  18. Amphiphilic crescent-moon-shaped microparticles formed by selective adsorption of colloids.

    PubMed

    Kim, Shin-Hyun; Abbaspourrad, Alireza; Weitz, David A

    2011-04-13

    We use a microfluidic device to prepare monodisperse amphiphilic particles in the shape of a crescent-moon and use these particles to stabilize oil droplets in water. The microfluidic device is comprised of a tapered capillary in a theta (?) shape that injects two oil phases into water in a single receiving capillary. One oil is a fluorocarbon, while the second is a photocurable monomer, which partially wets the first oil drop; silica colloids in the monomer migrate and adsorb to the interface with water but do not protrude into the oil interface. Upon UV-induced polymerization, solid particles with the shape of a crescent moon are formed; removal of fluorocarbon oil yields amphiphilic particles due to the selective adsorption of silica colloids. The resultant amphiphilic microparticles can be used to stabilize oil drops in a mixture of water and ethanol; if they are packed to sufficient surface density on the interface of the oil drop, they become immobilized, preventing direct contact between neighboring drops, thereby providing the stability. PMID:21417254

  19. Antineutrophil Cytoplasmic Antibodies-Negative Pauci-Immune Crescentic Glomerulonephritis Associated with Multiple Myeloma

    PubMed Central

    Anaele, Cyriacus Uzoma; Srisung, Weeraporn; Tomacruz, Yvette; Laski, Melvin

    2015-01-01

    Pauci-immune crescentic glomerulonephritis (PICGN) is most commonly associated with antineutrophil cytoplasmic antibodies (ANCA). We report a case of chronic, sclerosing ANCA-negative PICGN discovered when a patient presented with multiple myeloma. A 57-year-old woman presented with complaints of nausea, emesis and weakness. She was found to be in renal failure with a serum creatinine of 9.4 mg/dl, mild hyperkalemia and acidosis. She was noted to have normochromic, normocytic anemia with normal platelet and white cell counts, normal plasma proteins and serum protein electrophoresis. Further studies revealed increased concentrations of ? and ? light chains in a ratio of 34.89; a bone marrow biopsy found 12% plasma cells. Serum protein electrophoresis revealed no spike. ANCA, anti-glomerular basement membrane, antineutrophil antibody, hepatitis panel and serum complements were normal. A kidney biopsy result showed chronic sclerosing PICGN plus tubular necrosis, severe tubular atrophy, interstitial fibrosis and severe arteriosclerosis. Congo red stains were negative and electron microscopy showed no intraglomerular deposits. The patient was subsequently treated for myeloma with bortezomib and dexamethasone with good hematologic response but never recovered renal function. She remains on outpatient hemodialysis. Renal manifestations of myeloma often involve glomerular deposition disease, tubulointerstitial disease, with characteristic proteinaceous casts, or both. In contrast, our patient demonstrated neither of these findings but had chronic sclerosing PICGN. Crescentic glomerulonephritis occurring in patients with plasma cell dyscrasias has been previously reported, but the association remains extremely rare. PMID:26120578

  20. Valoriser les connaissances critiques d'une entreprise

    E-print Network

    Paris-Sud XI, Université de

    Valoriser les connaissances critiques d'une entreprise Jean-louis Ermine « Gestion Dynamique des critiques d'une entreprise Valoriser les connaissances critiques d'une entreprise Jean Louis Ermine INT, Institut National des Télécommunications 9, rue Charles Fourier 91011 Evry cedex, France jean-louis.ermine

  1. The shape of the barchan dunes of Southern Morocco

    Microsoft Academic Search

    G. Sauermann; P. Rognon; A. Poliakov; H. J. Herrmann

    2000-01-01

    We present detailed shape measurements of several barchan dunes in southern Morocco, near Laâyoune. Using these data, we disprove the concept of shape invariance of barchan dunes of different sizes. Nevertheless, some parts of the barchan dune scale and we try to distinguish these from non-scaling ones. Furthermore, we point out the importance of the exact position of the brink

  2. Geology Fieldnotes: Sleeping Bear Dunes National Lakeshore, Michigan

    NSDL National Science Digital Library

    The Sleeping Bear Dunes National Lakeshore site contains park geology information, park maps, photographs, related links, and visitor information. The park geology section discusses the geologic history of the region and formation of Sleeping Bear Dunes through westerly winds from Lake Michigan. The park maps section includes a map of the Sleeping Bear Dunes National Lakeshore and the surrounding area.

  3. Model for the genesis of coastal dune fields with vegetation

    Microsoft Academic Search

    Eric J. R. Parteli; Orencio Durán; Hans J. Herrmann

    2011-01-01

    Vegetation greatly affects the formation and dynamics of dune fields in coastal areas. In the present work, we use dune modeling in order to investigate the genesis and early development stages of coastal dune fields in the presence of vegetation. The model, which consists of a set of coupled equations for the turbulent wind field over the landscape, the saltation

  4. Sensitivity Analysis of Dune Height Measurements Along Cross-shore Profiles Using a Novel Method for Dune Ridge Extraction

    Microsoft Academic Search

    E. Hardin; H. Mitasova; M. Overton

    2010-01-01

    In barrier islands where communities are subjected to hazards including storm surge and high wave height, coastal dunes offer the first line of defense to property and vital infrastructure. When dunes are over-washed, substantial damage, including complete destruction of buildings and roads can occur. For this reason, dunes are an integral aspect of coastal hazard management. As new, more efficient

  5. A free cellular model of dune dynamics: Application to El Fangar spit dune system (Ebro Delta, Spain)

    NASA Astrophysics Data System (ADS)

    Barrio-Parra, Fernando; Rodríguez-Santalla, Inmaculada

    2014-01-01

    Currently, dune field surveying is employed to assess dune net volume changes and their accretion and erosion patterns. In dune fields with complex sediment sources and sink interactions such as El Fangar Spit (Ebro Delta, Spain), it is difficult to establish the sediment input and output with only net volume changes estimated by dune field surveying. This work presents a free dune dynamic cellular model that incorporates algorithms that introduce wind data into the erosion and transport processes. The model can be applied to dune systems with variable wind regime. A calibration methodology based on the morphological reproduction of the observed dune field evolution is proposed. The model and the calibration methodology is applied to a region of El Fangar dune system surveyed with DGPS on 15th and 18th April 2012. The difference between the final measured dune state and the best morphological reproduction obtained with the model is employed to estimate the sediment flux. This operation yields an output sand flux of 98.8 m3 and an input of 292.6 m3. This algorithm could have a great impact on the study of complex dune systems where the dunes act as sinks and sources of beach sediments and in the characterization of the beach-dune interactions.

  6. Origin of terrestrial gypsum dunes—Implications for Martian gypsum-rich dunes of Olympia Undae

    Microsoft Academic Search

    Anna Szynkiewicz; Ryan C. Ewing; Craig H. Moore; Mihaela Glamoclija; David Bustos; Lisa M. Pratt

    2010-01-01

    The Estancia, White Sands, Guadalupe and Cuatrociénegas Dune Fields are among the largest known aeolian gypsum sand-dune accumulations on Earth and occupy closed-drainage basins within the Rio Grande Rift. High sedimentation rates of lacustrine gypsum occur in topographic depressions within the closed basins. The gypsum accumulations result from long-term, complex, interaction between tectonism, climate, and a hydrologic cycle that involves

  7. Ground-water potentialities in the Crescent Valley, Eureka and Lander Counties, Nevada

    USGS Publications Warehouse

    Zones, Christie Paul

    1961-01-01

    The Crescent Valley is an intermontane basin in Eureka and Lander Counties, just south of the Humboldt River in north-central Nevada. The valley floor, with an area of about 150 square miles, has a shape that more nearly resembles a Y than a crescent, although the valley apparently was named after the arc described by its southern part and northeastern arm. The northwestern arm of the Y extends northward to the small railroad town of Beowawe on the Humboldt River; the northeastern arm lies east of the low Dry Hills. The leg of the Y extends southwestward toward a narrow gap which separates the Crescent Valley from the Carico Lake Valley. The total drainage area of the Crescent Valley-about 700 square miles--includes also the slopes of the bordering mountain ranges: the Shoshone Range to the west, the Cortez Mountains to the east, and the Toiyabe Range to the south. The early history of the Crescent Valley was dominated by mining of silver and gold, centered at Lander in the Shoshone Range and at Cortez and Mill Canyon in the Cortez Mountains, but in recent years the only major mining activity has been at Gold Acres; there open-pit mining of low-grade gold ore has supported a community of about 200. For many years the only agricultural enterprises in the valley were two cattle ranches, but recently addition lands have been developed for the raising of crops in the west-central part of the valley. The average annual precipitation upon the floor of the Crescent Valley is probably less than 7 inches, of which only a little more than 1 inch formally falls during the growing season (from June through September). This is far less than the requirement of any plants of economic value, and irrigation is essential to agricultural development. Small perennial streams rising in the mountains have long been utilized for domestic supply, mining and milling activities of the past, and irrigation, and recently some large wells have been developed for irrigation. In 1956 the total pumpage from wells in the valley was 2,300 acre-feet. The Crescent Valley is a basin in which has accumulated a large volume of sediments that had been eroded and transported by streams from the surrounding mountains. The deepest wells have penetrated only the upper 350 feet of these sediments, which on the basis of the known thickness of sediments in other intermontane basins in central Nevada may be as much as several thousand feet thick. Because this valley fill is saturated practically to the level of the valley floor, the total volume of ground water in storage amounts to millions of acre-feet. In practically all wells drilled to date, the water has been of a quality satisfactory for irrigation and domestic use. The amount of water that can be developed and used perennially is far smaller than the total in storage and is dependent upon the average annual recharge to the ground-water reservoir. This recharge comes principally from streams, fed largely by snowmelt, that drain the higher mountains. The average annum recharge to the valley fill is estimated to be about 13,000 acre-feet. This natural supply, which is largely consumed by native vegetation on the valley floor, constitutes a perennial supply for beneficial use only to the extent that the natural discharge can be reduced. In time, much of the natural discharge, can probably be salvaged, if it is economically feasible to pump ground water after water levels have been lowered as much as 100 feet in the areas that now appear to be favorable for the development of irrigation supplies. In 5 wells in the phreatophyte area, where the water table is within 3-8 feet of the land surface, the trends in water level have paralleled those, in precipitation-downward during the dry years 1952-55, upward in wetter 1956 and 1957, and as high in 1957 as at any time since 1948. In most wells there is also a seasonal fluctuation of 1-3 feet, from a high in the spring to a low in the fall. There is no evi

  8. Dunes on Titan observed by Cassini Radar

    Microsoft Academic Search

    J. Radebaugh; R. D. Lorenz; J. I. Lunine; S. D. Wall; G. Boubin; E. Reffet; R. L. Kirk; R. M. Lopes; E. R. Stofan; L. Soderblom; M. Allison; M. Janssen; P. Paillou; P. Callahan; C. Spencer

    2008-01-01

    Thousands of longitudinal dunes have recently been discovered by the Titan Radar Mapper on the surface of Titan. These are found mainly within ±30° of the equator in optically-, near-infrared-, and radar-dark regions, indicating a strong proportion of organics, and cover well over 5% of Titan's surface. Their longitudinal duneform, interactions with topography, and correlation with other aeolian forms indicate

  9. Diffusion au sommet d'une

    E-print Network

    Ramond, Thierry

    Diffusion au sommet d'une barri`ere de potentiel (I) Diffusion clas- sique/quantique Trajectoires classiques L'´equation de Schr¨odinger Op´erateur de diffusion Diffusion quantique en dimension 1 Matrice de diffusion Quelques r´esultats R´esonances Le Th´eor`eme de D. Robert et H. Tamura Trajectoires capt

  10. interministrielle d Dtail d'une offre

    E-print Network

    Canet, Léonie

    Bourse interministérielle d e l'emploi public Détail d'une offre Intitulé recruteur : Ecole. Date limite de candidature : 20 mars 2014 #12;Adresser CV + lettre de motivation + copie de la notification de situation administrative à l'adresse : m onique.paquin@oniris-nantes.fr Imprimer cette offre

  11. Crescentic acute glomerulonephritis with isolated C3 deposition: a case report and review of literature.

    PubMed

    Mao, Song; Xuan, Xiaoyan; Sha, Yugen; Zhao, Sanlong; Zhang, Aihua; Huang, Songming

    2015-01-01

    An eight-year-old girl, presenting with palpebral edema, gross hematuria, and foam in urine, was admitted to our hospital. Investigations indicated increased serum antistreptolysin O (ASO) and anti-mycoplasma antibody titers. Renal biopsy showed crescentic poststreptococcal acute glomerulonephritis (CPAGN) with isolated C3 deposition in the glomeruli. Electro-microscope examination showed subepithelial deposition of electron dense material. She received the double pulse therapies of methylprednisolone and cyclophosphamide as well as the treatment of oral prednisolone, angiotensin converting enzyme-II (ACE-II) inhibitor, dipyridamole and traditional Chinese medicine. The complete clinical remission was achieved after 9 months. No serious adverse effects were observed during the follow-up. Our findings indicated that CPAGN with isolated C3 deposition might have a favorable prognosis after aggressive immunosuppressive treatment. However, the influence of isolated C3 deposition on CPAGN prognosis remains to be clarified. PMID:25973075

  12. Crescentic acute glomerulonephritis with isolated C3 deposition: a case report and review of literature

    PubMed Central

    Mao, Song; Xuan, Xiaoyan; Sha, Yugen; Zhao, Sanlong; Zhang, Aihua; Huang, Songming

    2015-01-01

    An eight-year-old girl, presenting with palpebral edema, gross hematuria, and foam in urine, was admitted to our hospital. Investigations indicated increased serum antistreptolysin O (ASO) and anti-mycoplasma antibody titers. Renal biopsy showed crescentic poststreptococcal acute glomerulonephritis (CPAGN) with isolated C3 deposition in the glomeruli. Electro-microscope examination showed subepithelial deposition of electron dense material. She received the double pulse therapies of methylprednisolone and cyclophosphamide as well as the treatment of oral prednisolone, angiotensin converting enzyme-II (ACE-II) inhibitor, dipyridamole and traditional Chinese medicine. The complete clinical remission was achieved after 9 months. No serious adverse effects were observed during the follow-up. Our findings indicated that CPAGN with isolated C3 deposition might have a favorable prognosis after aggressive immunosuppressive treatment. However, the influence of isolated C3 deposition on CPAGN prognosis remains to be clarified. PMID:25973075

  13. Preservation of aeolian dunes by pahoehoe lava: An example from the Botucatu Formation (Early Cretaceous) in Mato Grosso do Sul state (Brazil), western margin of the Paraná Basin in South America

    NASA Astrophysics Data System (ADS)

    Holz, Michael; Soares, Ana Paula; Soares, Paulo Cesar

    2008-05-01

    This paper reports on a contact between Botucatu and Serra Geral Formations in Mato Grosso do Sul state (southwestern border of the Paraná Basin), where this kind of sediment-lava interaction has never been described before. The palaeodune registers mean palaeocurrent towards southwest, and the main volcano-sedimentary features are preserved ripples, striations, chevron and crescentic marks, empty or sand-filled tubes and cooling cracks. These features indicate that when lava flows covered the dune, the Botucatu erg was active in the study area, hence consolidating the concept of the non-existence of a hiatus between the Botucatu and Serra Geral Formations.

  14. Impact of the winter 2013-2014 series of severe Western Europe storms on a double-barred sandy coast: Beach and dune erosion and megacusp embayments

    NASA Astrophysics Data System (ADS)

    Castelle, Bruno; Marieu, Vincent; Bujan, Stéphane; Splinter, Kristen D.; Robinet, Arhur; Sénéchal, Nadia; Ferreira, Sophie

    2015-06-01

    The winter of 2013/2014 was characterized by a striking pattern of temporal and spatial extreme storm wave clustering in Western Europe. The 110-km long Gironde coast, SW France, was exposed to the most energetic wave conditions over the last 18 years. The period was outstanding in terms of the available energy to move sediment and cause large-scale erosion with the 2-month average significant wave height (Hs) exceeding 3.6 m, just below the 0.95 quantile, and 4 distinct 10-year return period storms with Hs > 9 m. These storm waves caused unprecedented beach and dune erosion along the Gironde coast, including severely damaged sea defences at the coastal towns. At the end of the winter, dune erosion scarp height was highly variable alongshore and often exceeded 10 m. Megacusp embayments were observed along the Gironde coast with an average alongshore spacing of 1000 m in the south progressively decreasing to 500 m in the north, with an average cross-shore amplitude of 20 m. While beach megacusps were previously observed to systematically couple to the inner bar along the Gironde coast during low- to moderate-energy wave conditions, severe storm-driven megacusp embayments cutting the dune were found to be enforced and coupled to the outer crescentic bar. A detailed inspection of the 1500 m-long bimonthly topographic surveys of Truc Vert beach shows that in early January 2014 the outstanding shore-normal incident storm swell 'Hercules', with Hs and peak wave period Tp peaking at 9.6 m and 22 s, respectively, triggered the formation of a localized megacusp embayment with the erosion scarp height exceeding 6 m in its centre where the dune retreat reached 30 m. The subsequent storms progressively smoothed the megacusp by the end of the winter, mostly through severe erosion of the megacusp horns. Because of the very long period (16 s < Tp < 23 s) storm waves with persistent shore-normal incidence, the well-developed outer crescentic bar observed prior to the winter did not straighten. Instead, the outer-bar three-dimensionality developed further, particularly during 'Hercules'. Our observations indicate that both the antecedent outer sandbar morphology and storm wave characteristics, including period and angle of incidence, govern patterns of beach and dune erosion along open multiple-barred sandy coasts during severe storms.

  15. Morpho-chronology of coastal dunes in Médoc. A new interpretation of Holocene dunes in Southwestern France

    NASA Astrophysics Data System (ADS)

    Tastet, Jean-Pierre; Pontee, Nigel I.

    1998-10-01

    Previous work on the coastal dunes in the Médoc region was carried out by the BRGM [Marionnaud, J.M., 1972. Carte géologique de la France (1/50000), Feuille St-Vivien-de-Médoc-Soulac-sur-Mer (729-730), Orléans: BRGM Notice explicative par J. Dubreuilh, J.M. Marionnaud (1973), 45 pp.; Dubreuilh, J., Marionnaud, J.M., 1973. Carte géologique de la France (1/50000), Feuille Lesparre-Médoc - Le Junca (753-754), Orléans: BRGM Notice explicative par J. Dubreuilh, J.M. Marionnaud, P. Andreieff (1973), 47 pp.]. They divided the dune systems into four chronological generations based on their morphology and comprising: (i) isolated barchans (>5100 yrs BP), (ii) parabolic dunes (5100-3000 yrs BP), (iii) localized areas of barchan dunes (2300-200 yrs BP), and (iv) present-day littoral dunes. This paper describes the dune morphology and presents a revised chronology for the Médoc dune systems based on historical records and a number of dated palaeosols. This paper confirms the existence of two generations (Buffault, P., 1942. Histoire des dunes maritimes de la Gascogne. Imprimerie Delmas, Bordeaux, 446 pp.) which are constituted by six different dune forms. The first of these generations is termed primary and consists of coalescent compound climbing parabolic dunes naturally fixed by vegetation (possibly mobile around 5000-3500 B.P. or 3000-2300 BP). The primary dunes were invaded by a second system named modern, which consists of simple barchans, isolated compound barchanoid ridges, a field of coalescent compound barchanoid ridges, simple parabolic dunes and compound digitate parabolic dunes; all of which are believed to have been active between 1500 and 200 BP. The highest degree of dune development occurs in the south of the area where the maximum expanse of sand deposits occurs on the continental shelf. In this region, the sequence of dunes inland from the coast consists of the littoral foredune, compound digitate parabolic dunes, simple barchans or isolated compound barchanoid ridges, and coalescent compound barchanoid ridges of increasing height and linearity further landwards. The barchanoid forms are interpreted as the amalgamation of landward migrating parabolic forms which arose as blowouts in the littoral foredunes. The large heights of the barchans can be explained by favourable conditions of sand accumulation due to the presence of the slacks (locally called `lèdes'), the Hourtin lake, and most importantly, the vegetated primary dune system, which curtailed landward sand transport past this point. To the south of the study area, inland of the coalescent compound barchanoid ridges belonging to the modern dune system, is a field of older coalescent compound climbing parabolic dunes of lower height belonging to the primary system.

  16. Pooh Bear rock and Mermaid Dune

    NASA Technical Reports Server (NTRS)

    1997-01-01

    One of the two forward cameras aboard Sojourner imaged this area of Martian terrain on Sol 26. The large rock dubbed 'Pooh Bear' is at far left, and stands between four and five inches high. Mermaid Dune is the smooth area stretching horizontally across the top quarter of the image. The Alpha Proton X-Ray Spectrometer (APXS) instrument aboard Sojourner will be deployed on Mermaid Dune, and the rover will later use its cleated wheels to dig into it.

    Mars Pathfinder is the second in NASA's Discovery program of low-cost spacecraft with highly focused science goals. The Jet Propulsion Laboratory, Pasadena, CA, developed and manages and Mars Pathfinder mission for NASA's Office of Space Science, Washington, D.C. JPL is an operating division of the California Institute of Technology (Caltech). The Imager for Mars Pathfinder (IMP) was developed by the University of Arizona Lunar and Planetary Laboratory under contract to JPL. Peter Smith is the Principal Investigator.

  17. Morphological barrier island changes and recovery of dunes after Hurricane Dennis, St. George Island, Florida

    E-print Network

    Fagherazzi, Sergio

    that increase dune survival are vegetation density, presence of woody vegetation, dune field continuity, dune September 2009 Keywords: Dune recovery LiDAR Overwash Hurricane Dennis Barrier island During the summer. The secondary dunes recovered at an average linear rate of 3­4 cm per month in the presence of vegetation

  18. Florida (Pensacola Beach) dune restoration Project General Project DescriPtion

    E-print Network

    2010. The primary dunes are the first natural line of defense for coastal Florida to prevent the loss appropriate dune vegetation approximately 40 feet seaward of the existing primary dune on 18-inch centersP to injury The Florida Dune Restoration Project will directly restore primary vegetated dune habitat injured

  19. 98 I The Johns Hopkins and the International Federation of Red Cross and Red Crescent Societies healthservices

    E-print Network

    Scharfstein, Daniel

    of Red Cross and Red Crescent Societies #12;Public health guide for emergencies I 99 Emergency. Key competencies To understand the consequences of disasters and the role of health services healthservices 3 Emergency health services Description This chapter provides guidance on key principles

  20. 136 I The Johns Hopkins and the International Federation of Red Cross and Red Crescent Societies Reproductive

    E-print Network

    Scharfstein, Daniel

    of Red Cross and Red Crescent Societies #12;Public health guide for emergencies I 137 Reproductive under Sphere. Key competencies To learn the definitions of basic reproductive health terms Reproductive healthcare 4 Health Centre - Treguine refugee camp, Chad Daniel Cima/International Federation

  1. 44 I The Johns Hopkins and the International Federation of Red Cross and Red Crescent Societies Healthsystems

    E-print Network

    Scharfstein, Daniel

    /International Federation of Red Cross and Red Crescent Societies #12;Public health guide for emergencies I 45 and references to accomplish key tasks. Key competencies To describe Sphere Project standards that support health Healthsystems andinfrastructure 2 Treguine Chad, Refugee Camp Health centre Photo: Daniel Cima

  2. Necrotizing and crescentic glomerulonephritis presenting with preserved renal function in patients with underlying multisystem autoimmune disease: a retrospective case series

    PubMed Central

    Tanna, Anisha; Randone, Olga; Tam, Frederick W. K.; Tarzi, Ruth M.; Levy, Jeremy B.; Griffith, Megan; Lightstone, Liz; Cook, H. Terence; Cairns, Tom; Pusey, Charles D.

    2015-01-01

    Objective. Necrotizing and crescentic GN usually presents with rapidly declining renal function, often in association with multisystem autoimmune disease, with a poor outcome if left untreated. We aimed to describe the features of patients who have presented with these histopathological findings but minimal disturbance of renal function. Methods. We conducted a retrospective review (1995–2011) of all adult patients with native renal biopsy–proven necrotizing or crescentic GN and normal serum creatinine (<120 ?mol/l) at our centre. Results. Thirty-eight patients were identified. The median creatinine at presentation was 84 ?mol/l and the median proportion of glomeruli affected by necrosis or crescents was 32%. Clinicopathological diagnoses were ANCA-associated GN (74%), LN (18%), anti-GBM disease (5%) and HScP (3%). Only 18% of cases had pre-existing diagnoses of underlying multisystem autoimmune disease, although the majority (89%) had extra-renal manifestations accompanying the renal diagnosis. All patients received immunosuppression and most had good long-term renal outcomes (median duration of follow-up 50 months), although two progressed to end-stage renal disease within 3 years. We estimate that renal biopsy had an important influence on treatment decisions in 82% of cases. Conclusion. Necrotizing and crescentic GN may present in patients with no or only minor disturbance of renal function. This often occurs in patients with underlying systemic autoimmune disease; early referral for biopsy may affect management and improve long-term outcomes in these cases. PMID:25431483

  3. Extension d'une valuation # Michel Vaquie

    E-print Network

    Extension d'une valuation # Michel Vaquiâ??e Abstract We want to determine all the extensions of a valuation # of a field K to a monogenic extension L of K, i.e. L = K(x) is the field of rational functions valuation for a given valuation µ of K[x], and has shown how we can recover any extension to L of a discrete

  4. Extension d'une valuation Michel Vaquie

    E-print Network

    Vaquie, Michel

    Extension d'une valuation Michel Vaqui´e Abstract We want to determine all the extensions of a valuation of a field K to a cyclic extension L of K, i.e. L = K(x) is the field of rational functions of x valuation for a given valuation µ of K[x], and has shown how we can recover any extension to L of a discrete

  5. D and D (Dunes and Devils)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    3 February 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows streaks created by late spring and early summer dust devils on a field of dark sand dunes on the floor of Hooke Crater.

    Location near: 45.0oS, 44.8oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  6. Avalanche grainflow on a simulated aeolian dune

    NASA Astrophysics Data System (ADS)

    Sutton, S. L. F.; McKenna Neuman, C.; Nickling, W.

    2013-09-01

    Avalanches maintain the slipface of aeolian dunes, which alters their airflow characteristics and sediment dynamics, and results in the development of grainflow cross-bedding. We report on a series of experiments in which avalanches were observed on a 1:1 replica of a small (1.2 m brink height) transverse dune in the Dune Simulation Wind Tunnel under wind velocities of 8-11 m s-1. Changes in slipface topography were observed photographically and measured utilizing a 3-D laser scanner with 1 mm2 spatial resolution. Avalanches in noncohesive sands were observed to progress through scarp recession from the point of initiation and continue until the slope angle is reduced. Changes in local slope confirm that the steep, pre-avalanche mean slope relaxes to a uniform value equal to the angle of repose of the test sand (32°) over all involved portions of the slipface. Avalanche volumes are measured, and demonstrate that avalanche magnitude is independent of wind speed over the range of velocities observed. This independence provides the potential to significantly simplify the modeling of grainflow as a function of only the total cross brink sediment transport.

  7. Annual monsoon rains recorded by Jurassic dunes.

    PubMed

    Loope, D B; Rowe, C M; Joeckel, R M

    2001-07-01

    Pangaea, the largest landmass in the Earth's history, was nearly bisected by the Equator during the late Palaeozoic and early Mesozoic eras. Modelling experiments and stratigraphic studies have suggested that the supercontinent generated a monsoonal atmospheric circulation that led to extreme seasonality, but direct evidence for annual rainfall periodicity has been lacking. In the Mesozoic era, about 190 million years ago, thick deposits of wind-blown sand accumulated in dunes of a vast, low-latitude desert at Pangaea's western margin. These deposits are now situated in the southwestern USA. Here we analyse slump masses in the annual depositional cycles within these deposits, which have been described for some outcrops of the Navajo Sandstone. Twenty-four slumps, which were generated by heavy rainfall, appear within one interval representing 36 years of dune migration. We interpret the positions of 20 of these masses to indicate slumping during summer monsoon rains, with the other four having been the result of winter storms. The slumped lee faces of these Jurassic dunes therefore represent a prehistoric record of yearly rain events. PMID:11452305

  8. Ecology, management and monitoring of grey dunes in Flanders

    Microsoft Academic Search

    Dries Bonte; Eric Cosyns; Maurice Hoffmann

    2004-01-01

    Grey dunes are a priority habitat type of the European Union Habitats Directive and demand special attention for conservation\\u000a and management. Knowledge of the ecology of coastal grey dunes can contribute to this policy. Dune grassland succession is\\u000a initiated by fixation and driven by the complex of soil formation (humus accumulation) and vegetation development. Leaching\\u000a and mobilization of CaCO3. which

  9. Camera Monitoring of Coastal Dune Erosion in a Macrotidal Environment

    NASA Astrophysics Data System (ADS)

    Kim, Taerim; Kim, Dongsoo

    2015-04-01

    The recent dune erosion in the west coast of Korea is serious in terms of its speed and harmful influence on the adjacent coastal waters as well as dune forest. The west coast of Korea is in the macro-intertidal environment and aeolian sediment transport on the intertidal flat is very active during an ebb tide, especially in winter. There is strong interaction between sand beach and dune by supplying or depositing sand. Coastal dune, as one part of beach system, contributes for beach recovery as well as preventing beach erosion by exchanging sands between beach and dune. Due to high tidal range, the boundary of sand dunes is outside the high water line during spring tide and it makes people think coastal dune is safe from wave forces causing beach erosion. However it seems that high waves during spring high tide cause serious erosion in a relatively short period. This paper investigates the erosion status of the dunes located in the JangHang beach in the southwest coast of Korean Peninsula, by analyzing images from camera monitoring system, and tide and wave data observed adjacent to the study site during the passage of 4 typhoons in 2012. It shows the importance of the timing of wave and tide condition in coastal dune erosion in macrotidal environment.

  10. Multi-spatial analysis of aeolian dune-field patterns

    NASA Astrophysics Data System (ADS)

    Ewing, Ryan C.; McDonald, George D.; Hayes, Alex G.

    2015-07-01

    Aeolian dune-fields are composed of different spatial scales of bedform patterns that respond to changes in environmental boundary conditions over a wide range of time scales. This study examines how variations in spatial scales of dune and ripple patterns found within dune fields are used in environmental reconstructions on Earth, Mars and Titan. Within a single bedform type, different spatial scales of bedforms emerge as a pattern evolves from an initial state into a well-organized pattern, such as with the transition from protodunes to dunes. Additionally, different types of bedforms, such as ripples, coarse-grained ripples and dunes, coexist at different spatial scales within a dune-field. Analysis of dune-field patterns at the intersection of different scales and types of bedforms at different stages of development provides a more comprehensive record of sediment supply and wind regime than analysis of a single scale and type of bedform. Interpretations of environmental conditions from any scale of bedform, however, are limited to environmental signals associated with the response time of that bedform. Large-scale dune-field patterns integrate signals over long-term climate cycles and reveal little about short-term variations in wind or sediment supply. Wind ripples respond instantly to changing conditions, but reveal little about longer-term variations in wind or sediment supply. Recognizing the response time scales across different spatial scales of bedforms maximizes environmental interpretations from dune-field patterns.

  11. Digital mapping of the extent of global dune systems

    NASA Astrophysics Data System (ADS)

    Hesse, Paul; Lancaster, Nicholas; Telfer, Matt

    2015-04-01

    Inland dune systems occur on all continents and at all latitudes, yet until now there is no digital map of their location and extent. We have compiled a new digital map of the extent of inland dune systems worldwide from published and unpublished sources, supplemented by manual digitizing of additional sand seas and dune fields. The digital database is compiled in ArcGIS, allowing mapping at scales from global to regional. The database contains spatial information on approximately 200 dune fields and sand seas ranging in size from less than 2 square km to as much as 630,000 sq km, covering a total global area of 29.4 million sq km. It includes both currently active unvegetated sand seas and dune fields, as well as partially vegetated and vegetated areas of dunes and sand sheets. Where available, the database contains information on dune type and status (active or stabilized). Manual digitizing of dune and sand sheet areas, as well as correction of existing digital coverages was accomplished mainly using ESRI imagery resources, with constant reference to ancillary information from publications and previous mapping. Compilation of the database required extensive research on the geographic names for different dune areas, as well as dunefield status and extent. The database and maps derived from it will be available online at http://inquadunesatlas.dri.edu/. We envisage it will be a dynamic and ongoing project and solicit corrections and additional information, including new and revised digital coverages, from the scientific community.

  12. Variation between bee communities on a sand dune complex in the Great Basin Desert, North America: Implications for sand dune conservation

    Microsoft Academic Search

    J. S. Wilson; O. J. Messinger; T. Griswold

    2009-01-01

    Sand dunes across the Mojave and Great Basin Deserts house rich bee communities. The pollination services these bees provide can be vital in maintaining the diverse, and often endemic, dune flora. These dune environments, however, are threatened by intense off-highway vehicle (OHV) use. Conservation efforts adopted by land managers often consist of setting aside a portion of a dune system

  13. Life history, habitat use and dispersal of a dune wolf spider (Pardosa monticola (Clerck, 1757) Lycosidae, Araneae) in the Flemish coastal dunes (Belgium)

    Microsoft Academic Search

    Dries Bonte; Jean-Pierre Maelfait

    2001-01-01

    Pardosa monticola (Araneae, Lycosidae) is a rare spider in Flanders. It is restricted to ther- mophilic mesotrophic (dune and heath) grasslands. Its life cycle and its habitat preference in the coastal dunes were analysed by interpreting data of more than 200 year-round pitfall-samplings. Viable populations are found in short dune grasslands (grazed by rabbits) and in mown young dune slacks.

  14. Climate change in the Fertile Crescent and implications of the recent Syrian drought.

    PubMed

    Kelley, Colin P; Mohtadi, Shahrzad; Cane, Mark A; Seager, Richard; Kushnir, Yochanan

    2015-03-17

    Before the Syrian uprising that began in 2011, the greater Fertile Crescent experienced the most severe drought in the instrumental record. For Syria, a country marked by poor governance and unsustainable agricultural and environmental policies, the drought had a catalytic effect, contributing to political unrest. We show that the recent decrease in Syrian precipitation is a combination of natural variability and a long-term drying trend, and the unusual severity of the observed drought is here shown to be highly unlikely without this trend. Precipitation changes in Syria are linked to rising mean sea-level pressure in the Eastern Mediterranean, which also shows a long-term trend. There has been also a long-term warming trend in the Eastern Mediterranean, adding to the drawdown of soil moisture. No natural cause is apparent for these trends, whereas the observed drying and warming are consistent with model studies of the response to increases in greenhouse gases. Furthermore, model studies show an increasingly drier and hotter future mean climate for the Eastern Mediterranean. Analyses of observations and model simulations indicate that a drought of the severity and duration of the recent Syrian drought, which is implicated in the current conflict, has become more than twice as likely as a consequence of human interference in the climate system. PMID:25733898

  15. A crescent shaped ALIX dimer targets ESCRT-III CHMP4 filaments

    PubMed Central

    Pires, R.; Hartlieb, B.; Signor, L.; Schoehn, G.; Lata, S.; Roessle, M.; Moriscot, C.; Popov, S.; Hinz, A.; Jamin, M.; Boyer, V.; Sadoul, R.; Forest, E.; Svergun, D. I.; Göttlinger, H. G.; Weissenhorn, W.

    2009-01-01

    ALIX recruits ESCRT-III CHMP4 and is involved in membrane remodeling during endosomal receptor sorting, budding of some enveloped viruses and cytokinesis. We show that ALIX dimerizes via the middle domain (ALIX-V) in solution. Structural modeling based on small angle X-ray scattering (SAXS) data reveal an elongated crescent shaped conformation for dimeric ALIX lacking the proline rich domain (ALIXBRO1-V). Mutations at the dimerization interface prevent dimerization and induce an open elongated monomeric conformation of ALIX-V as determined by SAXS modeling. ALIX dimerizes in vivo and dimeric ALIX co-localizes with CHMP4B upon co-expression. We show further that ALIX dimerization affects HIV-1 budding. C-terminally truncated activated CHMP4B retaining the ALIX binding site forms linear, circular and helical filaments in vitro, which can be bridged by ALIX. Our data suggest that dimeric ALIX represents the active form that interacts with ESCRT-III CHMP4 polymers and functions as a scaffolding protein during membrane remodeling processes. PMID:19523902

  16. Aeolian Processes of the Pismo-Oceano Dune Complex, California

    NASA Astrophysics Data System (ADS)

    Barrineau, C. P.; Tchakerian, V.; Houser, C.

    2012-12-01

    The Pismo Dunes are located approximately 250 km northwest of Los Angeles and consist of 90 km2 of transverse, parabolic and paleodunes. The Pismo Dunes are one of the largest dune complexes on the west coast and are the largest remaining south of San Francisco Bay, but despite their size, relatively few process morphology studies have focused on their form and history. Specifically, the dune field includes 12 km2 of actively migrating transverse dune ridges advancing onshore in three distinct phases separated by small depressions easily indentified using a LiDAR-generated elevation model. An early field investigation by Tchakerian (1983) revealed a uniform increase in slip face heights and crestline wavelengths inland with no apparent change in grain size. Measurement of recent aerial imagery shows variable migration rates throughout the dunes and wavelengths between 30 and 100 m closest to the beach, in the second ridge between 50 and 140 m, and from 70 to 250 m furthest inland. During El Niño and La Niña periods, westerly winds advance onshore nearly perpendicular to the crestlines, fueling episodic migration of the dune field. It is hypothesized that particularly strong ENSO periods may have led to the development of distinct dune phases with separating depressions and the development of defects along the dune crest. Defects associated with the wakes of incipient vegetation and inter-dune depressions are conspicuous and widespread, though localized and variable through time and space. Aerial imagery taken in September 1994 shows a wider, more even distribution of defects across the dune field than currently visible. The signal is, however, complicated by the closure of the dune field to oversand vehicles in 1982. The closure of much of the complex to vehicular traffic in 1982 may play a role, as Tchakerian's crestline wavelength measurements were far smaller than those obtained for this study while maintaining a likewise increase between phases. At a decadal scale, excessive vehicular traffic may have impeded the transition of emergent, defect-ridden dune forms into mature transverse ridges. Despite the astounding lack to studies focusing on the Pismo Dunes, the complex presents multiple opportunities for inquiry regarding climatic control on dune field evolution, defect law and complex landform pattern development, and long-term anthropogenic alteration of coastal process morphology.

  17. Riverine Eolian Dunes in Uruguay: OSL Ages and Paleoenvironmental Significance

    NASA Astrophysics Data System (ADS)

    Leigh, D. S.; Suarez, R.; Brook, G. A.

    2012-12-01

    Relict parabolic dunes occur along Rio Negro and Rio Tacuarembó in Uruguay under the current humid temperate climate. These dunes offer important terrestrial evidence of drier conditions in the past and may provide foresight about landscape consequences of future climate change. The ages of these dunes previously had not been measured by any absolute dating technique. Two dune fields were selected for optically stimulated luminescence (OSL) dating using the single aliquot regeneration method, including four samples along Rio Negro near Pueblo de la Arena and three samples along Rio Tacuarembó near Ansina. Results indicate that the dunes were active during the late Pleistocene, with five of the OSL ages in the 22 ka to 12 ka range. One OSL age at the Ansina dune field returned an age of 6 ka, indicating the possibility of limited dune reactivation during the Holocene. There is clear evidence of historical dune activation (e.g. buried fences) at both the Rio Negro and Rio Tacuarembó sites; one OSL sample from Rio Negro dunes confirms an historical age of 107 years BP. However, human land disturbance rather than climatic factors may explain the historical reactivation. Late Pleistocene dune activity in central Uruguay indicates much drier and windier paleoclimate (at least seasonally) than present, and correlates well with eolian activity in more arid parts of South America in western Argentina. Age and paleoenvironment of the riverine dunes in Uruguay are remarkably similar to those of the southeastern United States (USA), indicating similar patterns of paleoclimate in both hemispheres. Such similarities help to resolve the spatial patterns of global scale climate change.

  18. Relating climate and sand transport to incipient dune development.

    NASA Astrophysics Data System (ADS)

    van Puijenbroek, Marinka; Limpens, Juul; Gleichman, Maurits; Berendse, Frank

    2014-05-01

    Sea levels are continuously rising, increasing the risk of flooding and coastal erosion in low-elevation countries, such as the Netherlands. Coastal dunes are seen as a flexible and natural type of coastal defence, that is able to keep pace with rising water levels. Until now most research has focussed on dynamics and maintenance of established dunes, largely ignoring two critical transitions in early dune development: the transition from bare beach to vegetated incipient dune and that from incipient dune to established foredune. This knowledge is essential to enable more accurate prediction and even stimulation of new dune formation through sand nourishment. We explored the relative contributions of climate and sand transport to incipient dune development combining a 30 year time-series of aerial photographs (1979 - 2010) of the natural Wadden Island coast with high-resolution monitoring data of sand volume changes and climatic parameters. We selected 20 strips of 2.5 km in length along the coast of the Wadden Islands, with a 2 km buffer between them to avoid autocorrelation. For each of these strips of coast we assessed the changes in presence and area of incipient dunes over periods of 5-6 years. Change in fore dune volume and beach width were derived from high resolution beach elevation data. Seawater level and climate data were derived from a nearby meteorological station Preliminary analysis of the first half of the dataset showed that incipient dune area was positively related to beach width, but negatively to storm intensity. In our poster we will present the whole dataset and discuss the implications of our results for future dune development and anthropogenic sand nourishment schemes.

  19. Evidence for community structure and habitat partitioning in coastal dune stiletto flies at the Guadalupe-Nipomo dunes system, California.

    PubMed

    Holston, Kevin C

    2005-01-01

    This study provides empirical evidence for habitat selection by North American species of stiletto flies (Diptera: Therevidae), based on local distributions of adults and immatures, and the first hypothesis of community assemblages proposed for a stiletto fly community. Sites at three localities within the Guadalupe-Nipomo dune system were sampled for stiletto flies in 1997 and 2001 by sifting sand, malaise trapping, and hand netting. Nine species were collected from four ecological zones and three intermediate ecological zones: Acrosathe novella (Coquillett), Brachylinga baccata (Loew), Nebritus powelli (Webb and Irwin), Ozodiceromyia sp., Pherocera sp., Tabudamima melanophleba (Loew), Thereva comata Loew, Thereva elizabethae Holston and Irwin, and Thereva fucata Loew. Species associations of adults and larvae with habitats and ecological zones were consistent among sites, suggesting that local distributions of coastal dune stiletto fly species are influenced by differences in habitat selection. In habitats dominated by the arroyo willow,Salix lasiolepsis, stiletto fly larvae of three species were collected in local sympatry, demonstrating that S. lasiolepsis stands along stabilized dune ridges can provide an intermediate ecological zone linking active dune and riparian habitat in the Guadalupe-Nipomo dune system. Sites dominated by European beach grass, Ammophilia arenaria, blue gum, Eucalyptus globulus, and Monterey cypress, Cupressus macrocarpa, are considered unsuitable for stiletto flies, which emphasizes the importance of terrestrial habitats with native vegetation for stiletto fly species. The local distributions of stiletto fly species at the Guadalupe-Nipomo dune system allow the community to be divided into three assemblages; active dune, pioneer scrub, and scrub-riparian. These assemblages may be applicable to other coastal dune stiletto fly communities, and may have particular relevance to stiletto fly species collected in European coastal dunes. The results from this study provide a descriptive framework for studies testing habitat selection in coastal dune stiletto fly species and inform conservation of threatened dune insects. PMID:17119624

  20. Broadband colored-crescent generation in a single {beta}-barium-borate crystal by intense femtosecond pulses

    SciTech Connect

    Wang, L.; Fan, Y. X.; Zhu, H.; Yan, Z. D.; Zhu, S. N.; Wang, Z. L. [Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, 210093 Nanjing (China); Zeng, H. [State Key Laboratory of Precision Spectroscopy, East China Normal University, 200062 Shanghai (China); Wang, H.-T. [Department of Physics and National Laboratory of Solid State Microstructures, Nanjing University, 210093 Nanjing (China); School of Physics, Nankai University, 300071 Tianjin (China)

    2011-12-15

    A visible colored crescent with a bandwidth broader than 220 nm is observed experimentally by loosely focused femtosecond pulses in a bulk quadratic nonlinear crystal ({beta}-BBO crystal) at certain incident angles. Through the analysis based on a simple collinear phase-matching model, we suggest that the colored crescent might be the coexistence of spontaneous parametric down-conversions (SPDCs) in the infrared range and the corresponding efficient second-order harmonic generations (SHGs) that occur in a wide spectrum. We further provide a possible mechanism for the SHG process in which the phase-mismatching angles of the frequency doubling of SPDCs in {beta}-BBO crystal are assumed to be compensated by the strong diffraction effect during the self-focusing process of the generated intense SPDC signals.

  1. 36 CFR 7.88 - Indiana Dunes National Lakeshore.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...Public Property 1 2013-07-01 2013-07-01 false Indiana Dunes National Lakeshore. 7.88 Section 7.88 Parks...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.88 Indiana Dunes National Lakeshore. (a) Fishing. Unless...

  2. 36 CFR 7.88 - Indiana Dunes National Lakeshore.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...Public Property 1 2012-07-01 2012-07-01 false Indiana Dunes National Lakeshore. 7.88 Section 7.88 Parks...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.88 Indiana Dunes National Lakeshore. (a) Fishing. Unless...

  3. 36 CFR 7.88 - Indiana Dunes National Lakeshore.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Public Property 1 2011-07-01 2011-07-01 false Indiana Dunes National Lakeshore. 7.88 Section 7.88 Parks...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.88 Indiana Dunes National Lakeshore. (a) Fishing. Unless...

  4. 36 CFR 7.88 - Indiana Dunes National Lakeshore.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...Public Property 1 2014-07-01 2014-07-01 false Indiana Dunes National Lakeshore. 7.88 Section 7.88 Parks...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.88 Indiana Dunes National Lakeshore. (a) Fishing. Unless...

  5. The effects of psammophilous plants on sand dune dynamics

    NASA Astrophysics Data System (ADS)

    Bel, Golan; Ashkenazy, Yosef

    2014-07-01

    Mathematical models of sand dune dynamics have considered different types of sand dune cover. However, despite the important role of psammophilous plants (plants that flourish in moving-sand environments) in dune dynamics, the incorporation of their effects into mathematical models of sand dunes remains a challenging task. Here we propose a nonlinear physical model for the role of psammophilous plants in the stabilization and destabilization of sand dunes. There are two main mechanisms by which the wind affects these plants: (i) sand drift results in the burial and exposure of plants, a process that is known to result in an enhanced growth rate, and (ii) strong winds remove shoots and rhizomes and seed them in nearby locations, enhancing their growth rate. Our model describes the temporal evolution of the fractions of surface cover of regular vegetation, biogenic soil crust, and psammophilous plants. The latter reach their optimal growth under either (i) specific sand drift or (ii) specific wind power. The model exhibits complex bifurcation diagrams and dynamics, which explain observed phenomena, and it predicts new dune stabilization scenarios. Depending on the climatological conditions, it is possible to obtain one, two, or, predicted here for the first time, three stable dune states. Our model shows that the development of the different cover types depends on the precipitation rate and the wind power and that the psammophilous plants are not always the first to grow and stabilize the dunes.

  6. Large-eddy simulations of unidirectional water flow over dunes

    Microsoft Academic Search

    D. G. E. Grigoriadis; E. Balaras; A. A. Dimas

    2009-01-01

    The unidirectional, subcritical flow over fixed dunes is studied numerically using large-eddy simulation, while the immersed boundary method is implemented to incorporate the bed geometry. Results are presented for a typical dune shape and two Reynolds numbers, Re = 17,500 and Re = 93,500, on the basis of bulk velocity and water depth. The numerical predictions of velocity statistics at

  7. 36 CFR 7.80 - Sleeping Bear Dunes National Lakeshore.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...Property 1 2010-07-01 2010-07-01 false Sleeping Bear Dunes National Lakeshore. 7.80 Section 7.80 Parks...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.80 Sleeping Bear Dunes National Lakeshore. (a) Powerless flight....

  8. 36 CFR 7.80 - Sleeping Bear Dunes National Lakeshore.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...Property 1 2011-07-01 2011-07-01 false Sleeping Bear Dunes National Lakeshore. 7.80 Section 7.80 Parks...REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.80 Sleeping Bear Dunes National Lakeshore. (a) Powerless flight....

  9. Luminescence chronology of the inland sand dunes from SE India

    NASA Astrophysics Data System (ADS)

    Reddy, Dontireddy Venkat; Singaraju, Vuddaraju; Mishra, Rakesh; Kumar, Devender; Thomas, Puthusserry Joseph; Rao, Karra Kameshwa; Singhvi, Ashok Kumar

    2013-09-01

    Records of past climate changes have been preserved variously on the earth's surface. Sand dunes are one such prominent imprint, and it is suggested that their presence is an indicator of periods of transition from arid to less arid phases. We report inland sand dunes from Andhra Pradesh (SE India) spread over an area of ~ 500 km2, ~ 75 km inland from the east coast. The dune sands are examined to understand their provenance, transportation, timing of sand aggradation and their relationship to past climates. The dune distribution, grain morphology and the grain-size studies on sands suggest an aeolian origin. Physiography of the study area, heavy mineral assemblage, and abundance of quartz in the parent rocks indicate that the dune sands are largely derived from first-order streams emanating from hills in the region and from weathering of the Nellore schist belt. It appears that the geomorphology and wind direction pattern both facilitated and restricted the dune aggradation and preservation to a limited area. OSL dating of 47 dune samples ranged from the present to ~ 50 ka, thereby suggesting a long duration of sand-dune aggradation and/or reworking history.

  10. SEASONAL VARIABILITY IN SPECTRAL REFLECTANCE OF COASTAL DUNE VEGETATION

    Microsoft Academic Search

    Mark van Til; Annemieke Bijlmer

    2004-01-01

    The coastal dunes belong to the most important ecosystems in the Netherlands, but they have also suffered from prolonged desiccation, changes in land use, diminished coastal dynamics, and acidification. Environmental management is applied to counteract the deterioration of threatened dune vegetation and to maintain biodiversity. An efficient and reliable monitoring system is neces- sary to investigate autonomous vegetation development and

  11. Model for the genesis of coastal dune fields with vegetation

    NASA Astrophysics Data System (ADS)

    de M. Luna, Marco C. M.; Parteli, Eric J. R.; Durán, Orencio; Herrmann, Hans J.

    2011-06-01

    Vegetation greatly affects the formation and dynamics of dune fields in coastal areas. In the present work, we use dune modeling in order to investigate the genesis and early development stages of coastal dune fields in the presence of vegetation. The model, which consists of a set of coupled equations for the turbulent wind field over the landscape, the saltation flux and the growth of vegetation cover on the surface, is applied to calculate the evolution of a sand patch placed upwind of a vegetated terrain and submitted to unidirectional wind and constant sand influx. Different dune morphologies are obtained, depending on the characteristic rate of vegetation growth relative to wind strength: barchans, transverse dunes with trailing ridges, parabolic dunes and vegetated, alongshore sand barriers or foredunes. The existence of a vegetation-free backshore is found to be important for the nucleation timescale of coastal dune generations. The role of the sand influx and of the maximum vegetation cover density for the dune shape is also discussed.

  12. Environmental controls on coastal dune formation; Skallingen Spit, Denmark

    Microsoft Academic Search

    Troels Aagaard; Julian Orford; Andrew S. Murray

    2007-01-01

    Many coastal dune systems in Western Europe were emplaced during the Little Ice Age (LIA). The formation of such dune fields has generally been ascribed to a combination of low sea level and strong winds during that time period, providing a supply of sand from the exposed shoreface and sufficient wind energy to transport this sand landward. However, little information

  13. Moderate to severe hallux valgus deformity: correction with proximal crescentic osteotomy and distal soft-tissue release

    Microsoft Academic Search

    R. Zettl; H.-J. Trnka; M. Easley; M. Salzer; P. Ritschl

    2000-01-01

    Between 1991 and 1995, 96 patients (114 feet) were treated with a proximal crescentic metatarsal osteotomy and distal soft-tissue\\u000a procedure for moderate to severe hallux valgus deformity [intermetatarsal (IM) angle > 15, or hallux valgus (HV) angle >\\u000a 30]. At an average follow-up of 26 months, 8 men and 62 women (86 feet) with a mean age of 53.2 years

  14. Geomorphology of desert sand dunes: A review of recent progress

    NASA Astrophysics Data System (ADS)

    Livingstone, Ian; Wiggs, Giles F. S.; Weaver, Corinne M.

    2007-02-01

    Through the 1980s and 1990s studies of the geomorphology of desert sand dunes were dominated by field studies of wind flow and sand flow over individual dunes. Alongside these there were some attempts numerically to model dune development as well as some wind tunnel studies that investigated wind flow over dunes. As developments with equipment allowed, field measurements became more sophisticated. However, by the mid-1990s it was clear that even these more complex measurements were still unable to explain the mechanisms by which sand is entrained and transported. Most importantly, the attempt to measure the stresses imposed by the wind on the sand surface proved impossible, and the use of shear (or friction) velocity as a surrogate for shear stress also failed to deliver. At the same time it has become apparent that turbulent structures in the flow may be as or more important in explaining sand flux. In a development paralleled in fluvial geomorphology, aeolian geomorphologists have attempted to measure and model turbulent structures over dunes. Progress has recently been made through the use of more complex numerical models based on computational fluid dynamics (CFD). Some of the modelling work has also suggested that notions of dune 'equilibrium' form may not be particularly helpful. This range of recent developments has not meant that field studies are now redundant. For linear dunes careful observations of individual dunes have provided important data about how the dunes develop but in this particular field some progress has been made through ground-penetrating radar images of the internal structure of the dunes. The paradigm for studies of desert dune geomorphology for several decades has been that good quality empirical data about wind flow and sand flux will enable us to understand how dunes are created and maintain their form. At least some of the difficulty in the past arose from the plethora of undirected data generated by largely inductive field studies. More recently, attention has shifted-although not completely-to modelling approaches, and very considerable progress has been made in developing models of dune development. It is clear, however, that the models will continue to require accurate field observations in order for us to be able to develop a clear understanding of desert sand dune geomorphology.

  15. Sensitivity Analysis of Dune Height Measurements Along Cross-shore Profiles Using a Novel Method for Dune Ridge Extraction

    NASA Astrophysics Data System (ADS)

    Hardin, E.; Mitasova, H.; Overton, M.

    2010-12-01

    In barrier islands where communities are subjected to hazards including storm surge and high wave height, coastal dunes offer the first line of defense to property and vital infrastructure. When dunes are over-washed, substantial damage, including complete destruction of buildings and roads can occur. For this reason, dunes are an integral aspect of coastal hazard management. As new, more efficient mapping and analysis technologies evolve, currently used methodologies should be regularly be reexamined in order to ensure the development of the most effective coastal management strategies. Currently, topographical parameters, such as dune height, are usually measured along evenly spaced, shore-perpendicular beach profiles. In previous studies, profile spacing has varied from 20m to over 500m, however, it has been shown that dune height can vary substantially over tens of meters. Profile spacing is a compromise between the resources needed to perform high-resolution measurements and ensuring the capture of meaningful dune features. While it is often clear how the choice of profile spacing will affect the resources needed to perform the analysis, it is often unclear how spacing affects the ability to capture significant dune variation and prevent omission of a narrow dune breach that can open the way for significant flooding. In this study, the structure of alongshore variation in dune height is investigated. The studied dune ridge is located in the Outer Banks, North Carolina, USA and stretches 18km from south of Oregon Inlet (75:31:19W, 35:46:03N) to Rodanthe (75:27:56W, 35:36:31N). The dune ridge is extracted from a 0.5m resolution Digital Elevation Model (DEM) that was interpolated from airborne lidar data using regularized spline with tension. The lidar data was collected in March 2008 by the National Oceanic and Atmospheric Administration. A dune ridge is usually identified as the highest elevation along a shore-perpendicular profile or where ocean-facing slope meets landward-facing slope. In this study, a novel approach for dune ridge extraction is proposed. First, two alongshore end-points of the studied dune ridge are identified using a standard, profile-based method. Then, the dune ridge is traced as the least cost path connecting the two end-points on a cost surface that represents the cumulative penalty for tracing a low elevation path. The cost surface is derived from elevation (i.e., elevation is equal to the cologarithm of the cost). The extracted dune ridge is then sampled at the DEM resolution of 0.5m and analysis of dune ridge height is performed. Statistics on variation in dune height are computed to help understand the sensitivity of dune height measurements to profile spacing and placement. Preliminary results suggest that dune height becomes nearly uncorrelated within 50m and ranges on average nearly a half meter within a five meter window suggesting that dune height measurements are sensitive to profile placement.

  16. Spatiotemporal model for the progression of transgressive dunes

    NASA Astrophysics Data System (ADS)

    Yizhaq, Hezi; Ashkenazy, Yosef; Levin, Noam; Tsoar, Haim

    2013-10-01

    Transgressive dune fields, which are active sand areas surrounded by vegetation, exist on many coasts. In some regions like in Fraser Island in Australia, small dunes shrink while large ones grow, although both experience the same climatic conditions. We propose a general mathematical model for the spatiotemporal dynamics of vegetation cover on sand dunes and focus on the dynamics of transgressive dunes. Among other possibilities, the model predicts growth parallel to the wind with shrinkage perpendicular to the wind, where, depending on geometry and size, a transgressive dune can initially grow although eventually shrink. The larger is the initial area the slower its stabilization process. The model’s predictions are supported by field observations from Fraser Island in Australia.

  17. Measuring Possible Tsunami Currents from the April 1, 2014 Mw 8.2 Chile Earthquake in Crescent City, California

    NASA Astrophysics Data System (ADS)

    Admire, A. R.; Crawford, G. B.; Dengler, L. A.

    2014-12-01

    Crescent City, California has a long history of damaging tsunamis. Thirty-nine tsunamis have been recorded since 1933, including five that caused damage. Crescent City's harbor and small boat basin are particularly vulnerable to strong currents. Humboldt State University has installed Acoustic Doppler Profilers (ADPs) in order to directly measure water pressure fluctuations and currents caused by tsunamis. An instrument in Humboldt Bay, ~100 km south of Crescent City, recorded tsunamis generated by the 2010 Mw 8.7 Chile and 2011 Mw 9.0 Japan earthquakes and demonstrated the usefulness of ADPs in measuring tsunami currents. In 2013, an ADP was deployed in Crescent City's harbor adjacent to the NOAA tide gauge. On April 1, 2014, a Mw 8.2 earthquake occurred in northern Chile, producing a modest Pacific-wide tsunami and a 16 cm peak amplitude on the Crescent City tide gauge. We analyze the ADP data before and during the expected arrival of the April 2 tsunami to see if a tsunami signal is present. Tidal currents are generally small (5 cm/s or less). For two months before the tsunami, intermittent, high-frequency variability is present in velocity and pressure at periods on the order of 20, 9 and 5 min, which compare favorably to modal periods predicted using some simplified models of open-ended basins. For several hours after the tsunami arrival on April 2, spectral power levels in velocity and pressure around the 20 min period are notably enhanced. These results suggest that: (1) the observed periods of enhanced variability represent the first three modes (n=0, 1 and 2) of free oscillations in the harbor, (2) the dominant period of (non-tidal) oscillations observed during the April 2, 2014 tsunami (~20 min) and during previous tsunamis (e.g., the water level record for the March 11, 2011 tsunami; also ~20 min) represents harbor resonance corresponding to the lowest order mode, and (3) this event is very near the ADP limit of detectability with peak tsunami currents of 5-10 cm/s and higher frequency variability and instrument noise root-mean-squared amplitude of 4-5 cm/s.

  18. Late Pleistocene dune activity in the central Great Plains, USA

    USGS Publications Warehouse

    Mason, J.A.; Swinehart, J.B.; Hanson, P.R.; Loope, D.B.; Goble, R.J.; Miao, X.; Schmeisser, R.L.

    2011-01-01

    Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20-25 ka are interbedded with loess south of the Sand Hills. Several of the large dunes sampled in the Sand Hills clearly contain a substantial core of Late Pleistocene sand; thus, they had developed by the Late Pleistocene and were fully mobile at that time, although substantial sand deposition and extensive longitudinal dune construction occurred during the Holocene. Many of the Late Pleistocene OSL ages fall between 17 and 14 ka, but it is likely that these ages represent only the later part of a longer period of dune construction and migration. At several sites, significant Late Pleistocene or Holocene large-dune migration also probably occurred after the time represented by the Pleistocene OSL ages. Sedimentary structures in Late Pleistocene eolian sand and the forms of large dunes potentially constructed in the Late Pleistocene both indicate sand transport dominated by northerly to westerly winds, consistent with Late Pleistocene loess transport directions. Numerical modeling of the climate of the Last Glacial Maximum has often yielded mean monthly surface winds southwest of the Laurentide Ice Sheet that are consistent with this geologic evidence, despite strengthened anticyclonic circulation over the ice sheet. Mobility of large dunes during the Late Pleistocene on the central Great Plains may have been the result of cold, short growing seasons with relatively low precipitation and low atmospheric CO2 that increased plant moisture stress, limiting the ability of vegetation to stabilize active dune sand. The apparent coexistence of large mobile dunes with boreal forest taxa suggests a Late Pleistocene environment with few modern analogs. ?? 2011 Elsevier Ltd.

  19. Large-eddy simulation of unidirectional turbulent flow over dunes

    NASA Astrophysics Data System (ADS)

    Omidyeganeh, Mohammad

    We performed large eddy simulation of the flow over a series of two- and three-dimensional dune geometries at laboratory scale using the Lagrangian dynamic eddy-viscosity subgrid-scale model. First, we studied the flow over a standard 2D transverse dune geometry, then bedform three-dimensionality was imposed. Finally, we investigated the turbulent flow over barchan dunes. The results are validated by comparison with simulations and experiments for the 2D dune case, while the results of the 3D dunes are validated qualitatively against experiments. The flow over transverse dunes separates at the dune crest, generating a shear layer that plays a crucial role in the transport of momentum and energy, as well as the generation of coherent structures. Spanwise vortices are generated in the separated shear; as they are advected, they undergo lateral instabilities and develop into horseshoe-like structures and finally reach the surface. The ejection that occurs between the legs of the vortex creates the upwelling and downdrafting events on the free surface known as "boils". The three-dimensional separation of flow at the crestline alters the distribution of wall pressure, which may cause secondary flow across the stream. The mean flow is characterized by a pair of counter-rotating streamwise vortices, with core radii of the order of the flow depth. Staggering the crestlines alters the secondary motion; two pairs of streamwise vortices appear (a strong one, centred about the lobe, and a weaker one, coming from the previous dune, centred around the saddle). The flow over barchan dunes presents significant differences to that over transverse dunes. The flow near the bed, upstream of the dune, diverges from the centerline plane; the flow close to the centerline plane separates at the crest and reattaches on the bed. Away from the centerline plane and along the horns, flow separation occurs intermittently. The flow in the separation bubble is routed towards the horns and leaves the dune at the tips. Barchan dunes induce two counter-rotating streamwise vortices, along each of the horns, which direct high-momentum fluid toward the symmetry plane and low-momentum fluid near the bed away from the centerline.

  20. Effects of sand fences on coastal dune vegetation distribution

    NASA Astrophysics Data System (ADS)

    Grafals-Soto, Rosana

    2012-04-01

    Sand fences are important human adjustments modifying the morphology of developed shores. The effects of sand fences on sediment transport and deposition in their initial stages have been well studied, but little is known about the effect of deteriorated sand fences that have become partially buried low scale barriers within the dune, potentially benefiting vegetation growth by protecting it from onshore stress. Data on vegetation, topography and fence characteristics were gathered at three dune sites in Ocean City, New Jersey on September 2007 and March 2008 to evaluate the effect of fences within the dune on vegetation distribution. Variables include: distance landward of dune toe, degree of sheltering from onshore stressors, net change in surface elevation (deposition or erosion), vegetation diversity and density, presence of remnant fence, and distance landward of fence. Results for the studied environment reveal that 1) vegetation diversity or density does not increase near remnant fences because most remnants are lower than average vegetation height and can not provide shelter; but 2) vegetation distribution is related to topographic variables, such as degree of sheltering, that are most likely the result of sand accretion caused by fence deployment. Fence deployment that prioritizes the creation of topographically diverse dunes within a restricted space may increase the diversity and density of the vegetation, and the resilience and value of developed dunes. Managers should consider the benefits of using sand fences on appropriately wide beaches to create a protective dune that is also diverse, functional and better able to adapt to change.

  1. Vegetation controls on the maximum size of coastal dunes

    NASA Astrophysics Data System (ADS)

    Duran Vinent, Orencio; Moore, Laura J.

    2014-05-01

    Coastal dunes, in particular foredunes, support a resilient ecosystem and reduce coastal vulnerability to storms. In contrast to dry desert dunes, coastal dunes arise from interactions between biological and physical processes. Ecologists have traditionally addressed coastal ecosystems by assuming that they adapt to preexisting dune topography, whereas geomorphologists have studied the properties of foredunes primarily in connection to physical, not biological, factors. Here, we study foredune development using an ecomorphodynamic model that resolves the co-evolution of topography and vegetation in response to both physical and ecological factors. We find that foredune growth is eventually limited by a negative feedback between wind flow and topography. As a consequence, steady state foredunes are scale invariant, which allows us to derive scaling relations for maximum foredune height and formation time. These relations suggest that plant zonation (in particular for strand `dune-building' species) is the primary factor controlling the maximum size of foredunes and therefore the amount of sand stored in a coastal dune system. We also find that aeolian sand supply to the dunes determines the time scale of foredune formation. These results offer a potential explanation for the empirical relation between beach type and foredune size, in which large (small) foredunes are found on dissipative (reflective) beaches: higher waves associated with dissipative beaches increase the disturbance of strand species which shifts foredune formation landwards and thus leads to larger foredunes.

  2. Absolute dune ages and implications for the time of formation of gullies in Nirgal Vallis, Mars

    Microsoft Academic Search

    D. Reiss; S. van Gasselt; G. Neukum; R. Jaumann

    2004-01-01

    Transverse dunes cover the valley floor of Nirgal Vallis, a 670 km long valley network at 318°E and 29°S. The dunes are superposed by small undeformed impact craters, which implies that the dunes are inactive under present atmospheric conditions. The last active phase of dune movement (absolute age) can be determined by crater size frequency distributions. The derived absolute ages

  3. Arbuscular mycorrhizas in a tropical coastal dune system in Yucatan, Mexico

    Microsoft Academic Search

    José A. Ramos-Zapata; Roxana Zapata-Trujillo; Juan J. Ortíz-Díaz; Patricia Guadarrama

    2011-01-01

    The main goal of this work was to determine the presence of arbuscular mycorrhizas in coastal dunes of Sisal, Mexico, and the seasonal and spatial changes in the arbuscular mycorrhizal fungal (AMF) community. The study was conducted at three coastal dune zones: embryonic, mobile and stabilized dunes. At each dune zone we chose five dominant plant species, collected roots and

  4. Using Long-Term Census Data to Inform Restoration Methods for Coastal Dune Vegetation

    E-print Network

    Miller, Thomas E.

    Using Long-Term Census Data to Inform Restoration Methods for Coastal Dune Vegetation Elise S Barrier Island . Coastal ecology . Dune zone . Disturbance . Dune vegetation . Storm response Introduction), with varied results. Restoration strategies can be difficult to implement successfully in coastal dune systems

  5. Chondrocalcinose articulaire révélatrice d'une hypercalcémie hypocalciurique familiale: à propos d'une observation

    PubMed Central

    Frikha, Faten; Snoussi, Mouna; Salah, Raida Ben; Loukil, Hanen; Bahloul, Zouhir

    2015-01-01

    L'hypercalcémie hypocalciurique familiale (HHF) est une maladie bénigne à transmission autosomique dominante, caractérisée par une hypercalcémie persistante béhigne, une hypocalciurie, et des concentrations de parathormone (PTH) normales ou modérément élevées, sans complication secondaire à l'hypercalcémie. Nous rapportons l'observation d'un patient ayant présenté une chondrocalcinose articulaire révélatrice d'une HHF. A travers cette observation nous essayons de décrire les aspects épidémiologiques, les caractéristiques cliniques, et paracliniques de cette association.

  6. Sand dunes on the central Delmarva Peninsula, Maryland and Delaware

    USGS Publications Warehouse

    Denny, Charles Storrow; Owens, James Patrick

    1979-01-01

    Inconspicuous ancient sand dunes are present in parts of the central Delmarva Peninsula, Maryland and Delaware. Many dunes are roughly V-shaped, built by northwest winds, especially on the east sides of some of the large rivers. On the uplands, the form and spacing of the dunes are variable. A surficial blanket composed mainly of medium and fine-grained sand-the Parsonsburg Sand-forms both the ancient dunes and the broad plains between the dunes. The sand that forms the dunes is massive and intensely burrowed in the upper part; traces of horizontal or slightly inclined bedding appear near the base. Quartz is the dominant mineral constituent of the sand. Microline is abundant in the very fine to fine sand fraction. The heavy-mineral assemblages (high zircon, tourmaline, rutile) are more mature than in most of the possible source rocks. The most abundant minerals in the clay-sized fraction are dioctahedral vermiculite, kaolinite, illite, montmorillonite, and gibbsite. The first four minerals are common in deposits of late Wisconsin and Holocene age. The gibbsite may be detrital, coming from weathered rocks of Tertiary age. The soil profile in the dune sand is weakly to moderately developed. At or near the base of the Parsonsburg Sand are peaty beds that range in age from about 30,000 to about 13,000 radiocarbon years B.P. Microfloral assemblages in the peaty beds suggest that the dunes on the uplands formed in a spruce parkland during the late Wisconsin glacial maximum. The river dunes may also be of late Wisconsin age, but could be Holocene.

  7. An introduction to the INQUA Dunes Atlas Chronologic Database

    NASA Astrophysics Data System (ADS)

    Lancaster, Nicholas; Bristow, Charlie; Bubenzer, Olaf; Burrough, Sallie; Duller, Geoff; Halfen, Alan; Hesse, Paul; Roskin, Joel; Singhvi, Ashok; Thomas, David; Tripaldi, Alfonsina; Yang, Xiaoping; Wolfe, Stephen; Zarate, Marcelo

    2015-04-01

    The INQUA Dunes Atlas project has developed a global digital database of chronologic information for periods of desert sand dune accumulation and stabilization. The database currently contains 3278 luminescence and 535 radiocarbon records of directly dated periods of aeolian sand deposition from 1200 inland dune locations throughout the world, mostly in low- and mid-latitudes. Co-authors of this abstract have compiled data for their geographic region of expertise. Additional data are being added from publications, reports, and theses and dissertations as they become available. In addition to age data, the database includes information on the site location (including coordinates), dune type, and stratigraphic context, pertinent analytical information (e.g. luminescence procedures), and literature citations to the original data source (with doi). The database has so far enabled: (1) analysis of patterns of dated dune deposits at multiple temporal and spatial scales; (2) correlation of these patterns with other paleoclimatic proxies; and (3) assessment of the paleoclimatic and paleohydrologic implications of periods of aeolian deposition. The database has highlighted several issues with the available luminescence data set, especially the uneven spatial coverage of dated dune deposits and the heterogenous nature of the dune sedimentary record in many areas. It is clear that resolution of these issues to provide a better understanding of dune and dunefield responses to Quaternary climate change is not just a matter of additional dates. A systematic dating program that reflects fundamental patterns of dunefield sensitivity to climatic and hydrologic changes and relates dated deposits to patterns of dune morphology and sedimentology is needed as a research priority.

  8. Slow Progress in Dune (Right Front Wheel)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The right front wheel of NASA's Mars Exploration Rover Opportunity makes slow but steady progress through soft dune material in this movie clip of frames taken by the rover's front hazard identification camera over a period of several days. The sequence starts on Opportunity's 460th martian day, or sol (May 10, 2005) and ends 11 days later. In eight drives during that period, Opportunity advanced a total of 26 centimeters (10 inches) while spinning its wheels enough to have driven 46 meters (151 feet) if there were no slippage. The motion appears to speed up near the end of the clip, but that is an artifact of individual frames being taken less frequently.

  9. Slow Progress in Dune (Left Front Wheel)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The left front wheel of NASA's Mars Exploration Rover Opportunity makes slow but steady progress through soft dune material in this movie clip of frames taken by the rover's front hazard identification camera over a period of several days. The sequence starts on Opportunity's 460th martian day, or sol (May 10, 2005) and ends 11 days later. In eight drives during that period, Opportunity advanced a total of 26 centimeters (10 inches) while spinning its wheels enough to have driven 46 meters (151 feet) if there were no slippage. The motion appears to speed up near the end of the clip, but that is an artifact of individual frames being taken less frequently.

  10. Slow Progress in Dune (Left Rear Wheel)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The left rear wheel of NASA's Mars Exploration Rover Opportunity makes slow but steady progress through soft dune material in this movie clip of frames taken by the rover's rear hazard identification camera over a period of several days. The sequence starts on Opportunity's 460th martian day, or sol (May 10, 2005) and ends 11 days later. In eight drives during that period, Opportunity advanced a total of 26 centimeters (10 inches) while spinning its wheels enough to have driven 46 meters (151 feet) if there were no slippage. The motion appears to speed up near the end of the clip, but that is an artifact of individual frames being taken less frequently.

  11. Slow Progress in Dune (Right Rear Wheel)

    NASA Technical Reports Server (NTRS)

    2005-01-01

    The right rear wheel of NASA's Mars Exploration Rover Opportunity makes slow but steady progress through soft dune material in this movie clip of frames taken by the rover's rear hazard identification camera over a period of several days. The wheel is largely hidden by a cable bundle. The sequence starts on Opportunity's 460th martian day, or sol (May 10, 2005) and ends 11 days later. In eight drives during that period, Opportunity advanced a total of 26 centimeters (10 inches) while spinning its wheels enough to have driven 46 meters (151 feet) if there were no slippage. The motion appears to speed up near the end of the clip, but that is an artifact of individual frames being taken less frequently.

  12. Sources and sinks of nitrogen and phosphorus to a deep, oligotrophic lake, Lake Crescent, Olympic National Park, Washington

    USGS Publications Warehouse

    Moran, P.W.; Cox, S.E.; Embrey, S.S.; Huffman, R.L.; Olsen, T.D.; Fradkin, S.C.

    2012-01-01

    Lake Crescent, in Olympic National Park in the northwest corner of Washington State is a deep-water lake renowned for its pristine water quality and oligotrophic nature. To examine the major sources and sinks of nutrients (as total nitrogen, total phosphorus, and dissolved nitrate), a study was conducted in the Lake Crescent watershed. The study involved measuring five major inflow streams, the Lyre River as the major outflow, recording weather and climatic data, coring lake bed sediment, and analyzing nutrient chemistry in several relevant media over 14 months. Water samples for total nitrogen, total phosphorous, and dissolved nitrate from the five inflow streams, the outlet Lyre River, and two stations in the lake were collected monthly from May 2006 through May 2007. Periodic samples of shallow water from temporary sampling wells were collected at numerous locations around the lake. Concentrations of nutrients detected in Lake Crescent and tributaries were then applied to the water budget estimates to arrive at monthly and annual loads from various environmental components within the watershed. Other sources, such as leaf litter, pollen, or automobile exhaust were estimated from annual values obtained from various literature sources. This information then was used to construct a nutrient budget for total nitrogen and total phosphorus. The nitrogen budget generally highlights vehicle traffic-diesel trucks in particular-along U.S. Highway 101 as a potential major anthropogenic source of nitrogen compounds in the lake. In contrast, contribution of nitrogen compounds from onsite septic systems appears to be relatively minor related to the other sources identified.

  13. A Probabilistic Tsunami Hazard Assessment Methodology and Its Application to Crescent City, CA

    NASA Astrophysics Data System (ADS)

    Gonzalez, F. I.; Leveque, R. J.; Waagan, K.; Adams, L.; Lin, G.

    2012-12-01

    A PTHA methodology, based in large part on Probabilistic Seismic Hazard Assessment methods (e.g., Cornell, 1968; SSHAC, 1997; Geist and Parsons, 2005), was previously applied to Seaside, OR (Gonzalez, et al., 2009). This initial version of the method has been updated to include: a revised method to estimate tidal uncertainty; an improved method for generating stochastic realizations to estimate slip distribution uncertainty (Mai and Beroza, 2002; Blair, et al., 2011); additional near-field sources in the Cascadia Subduction Zone, based on the work of Goldfinger, et al. (2012); far-field sources in Japan, based on information updated since the 3 March 2011 Tohoku tsunami (Japan Earthquake Research Committee, 2011). The GeoClaw tsunami model (Berger, et. al, 2011) is used to simulate generation, propagation and inundation. We will discuss this revised PTHA methodology and the results of its application to Crescent City, CA. Berger, M.J., D. L. George, R. J. LeVeque, and K. T. Mandli, The GeoClaw software for depth-averaged flows with adaptive refinement, Adv. Water Res. 34 (2011), pp. 1195-1206. Blair, J.L., McCrory, P.A., Oppenheimer, D.H., and Waldhauser, F. (2011): A Geo-referenced 3D model of the Juan de Fuca Slab and associated seismicity: U.S. Geological Survey Data Series 633, v.1.0, available at http://pubs.usgs.gov/ds/633/. Cornell, C. A. (1968): Engineering seismic risk analysis, Bull. Seismol. Soc. Am., 58, 1583-1606. Geist, E. L., and T. Parsons (2005): Probabilistic Analysis of Tsunami Hazards, Nat. Hazards, 37 (3), 277-314. Goldfinger, C., Nelson, C.H., Morey, A.E., Johnson, J.E., Patton, J.R., Karabanov, E., Gutiérrez-Pastor, J., Eriksson, A.T., Gràcia, E., Dunhill, G., Enkin, R.J., Dallimore, A., and Vallier, T. (2012): Turbidite event history—Methods and implications for Holocene paleoseismicity of the Cascadia subduction zone: U.S. Geological Survey Professional Paper 1661-F, 170 p. (Available at http://pubs.usgs.gov/pp/pp1661f/). González, F.I., E.L. Geist, B. Jaffe, U. Kânoglu, H. Mofjeld, C.E. Synolakis, V.V Titov, D. Arcas, D. Bellomo, D. Carlton, T. Horning, J. Johnson, J. Newman, T. Parsons, R. Peters, C. Peterson, G .Priest, A. Venturato, J. Weber, F. Wong, and A. Yalciner (2009): Probabilistic Tsunami Hazard Assessment at Seaside, Oregon, for Near- and Far-Field Seismic Sources, J. Geophys. Res., 114, C11023, doi:10.1029/2008JC005132. Japan Earthquake Research Committee, (2011): http://www.jishin.go.jp/main/p_hyoka02.htm Mai, P. M., and G. C. Beroza (2002): A spatial random field model to characterize complexity in earthquake slip, J. Geophys. Res., 107(B11), 2308, doi:10.1029/2001JB000588. SSHAC (Senior Seismic Hazard Analysis Committee) (1997): Recommendations for Probabilistic Seismic Hazard Analysis: Guidance on Uncertainty and Use of Experts, Main Report Rep. NUREG/CR-6372 UCRL-ID-122160 Vol. 1, 256 pp, U.S. Nuclear Regulatory Commission.

  14. Control of Sand Movement on Model Dune by Fence Installation

    NASA Astrophysics Data System (ADS)

    Sakamoto, Yusuke; Shimazu, Shota; Tsukahara, Takahiro; Yamamoto, Makoto; Kawaguchi, Yasuo

    2010-03-01

    Recent desertification has been one of serious environmental issues. It is important to elucidate mechanisms of the sand movement from sand dunes with considering the relations between the dune shape and the turbulent air flow. This relation can be applied to predict and prevent the desertification. In this study, the shape of the dune surface and the erosion rate are measured by the method of laser-sheet visualization. Laser-doppler velocimetry (LDV) has been used for turbulence measurement. Effects of an installed fence on the erosion rate are discussed with emphasis on influences of its position and height. The erosion has been either suppressed or enhanced by the fence. Since there exist two strong erosion areas due to the backflow and wake induced by the fence. In the present experimental conditions, the top of the dune is the most suitable position of the fence for preventing erosion.

  15. Song of the Dunes as a Self-Synchronized Instrument

    NASA Astrophysics Data System (ADS)

    Douady, S.; Manning, A.; Hersen, P.; Elbelrhiti, H.; Protière, S.; Daerr, A.; Kabbachi, B.

    2006-07-01

    Since Marco Polo it has been known that some sand dunes have the peculiar ability to emit a loud sound with a well-defined frequency, sometimes for several minutes. The origin of this sustained sound has remained mysterious, partly because of its rarity in nature. It has been recognized that the sound is not due to the air flow around the dunes but to the motion of an avalanche, and not to an acoustic excitation of the grains but to their relative motion. By comparing singing dunes around the world and two controlled experiments, in the laboratory and the field, we prove that the frequency of the sound is the frequency of the relative motion of the sand grains. Sound is produced because moving grains synchronize their motions. The laboratory experiment shows that the dune is not needed for sound emission. A velocity threshold for sound emission is found in both experiments, and an interpretation is proposed.

  16. Song of the dunes as a self-synchronized instrument.

    PubMed

    Douady, S; Manning, A; Hersen, P; Elbelrhiti, H; Protière, S; Daerr, A; Kabbachi, B

    2006-07-01

    Since Marco Polo it has been known that some sand dunes have the peculiar ability to emit a loud sound with a well-defined frequency, sometimes for several minutes. The origin of this sustained sound has remained mysterious, partly because of its rarity in nature. It has been recognized that the sound is not due to the air flow around the dunes but to the motion of an avalanche, and not to an acoustic excitation of the grains but to their relative motion. By comparing singing dunes around the world and two controlled experiments, in the laboratory and the field, we prove that the frequency of the sound is the frequency of the relative motion of the sand grains. Sound is produced because moving grains synchronize their motions. The laboratory experiment shows that the dune is not needed for sound emission. A velocity threshold for sound emission is found in both experiments, and an interpretation is proposed. PMID:16907409

  17. Recruitment limitation of native species in invaded coastal dune communities

    Microsoft Academic Search

    Kris French; Tanya J. Mason; Natalie Sullivan

    2011-01-01

    Recruitment limitation may limit the ability of sites to regenerate after disturbances such as weed invasion and weed management.\\u000a We investigated seed bank constraints and dispersal limitation in coastal dune communities on the east coast of Australia.\\u000a The ability of sites to regenerate naturally following weed removal was assessed in coastal dune communities invaded by the\\u000a invasive alien, bitou bush

  18. Soil pH and species diversity in coastal dunes

    Microsoft Academic Search

    M. Isermann

    2005-01-01

    Soil pH was measured at two different spatial scales in coastal dunes on Norderney, North Sea, and in Mecklenburg-Vorpommern, Baltic Sea, Germany. Relationships between the variability in soil pH, species richness and species diversity are presented. Species richness and diversity were highest in grey dunes, where soil pH was at intermediate levels; both variables were lower in yellow and brown

  19. Climate and coastal dune vegetation: disturbance, recovery, and succession

    Microsoft Academic Search

    Thomas E. MillerÆElise; Elise S. Gornish; Hannah L. Buckley

    2010-01-01

    The sand dune habitats found on barrier islands and other coastal areas support a dynamic plant community while protecting\\u000a areas further inland from waves and wind. Foredune, interdune, and backdune habitats common to most coastal dunes have very\\u000a different vegetation, likely because of the interplay among plant succession, exposure, disturbance, and resource availability.\\u000a However, surprisingly few long-term data are available

  20. Oak dune forests in Denmark and their ecology

    Microsoft Academic Search

    Jonas E Lawesson; Peter Wind

    2002-01-01

    Floristic and structural data of oak dune forests in western Jutland (Kaergård and Blåbjerg) were collected in 1998 and compared with previous studies of Danish oligotrophic oak forests.A hierarchical divisive clustering resulted in four main clusters, containing two coastal oak vegetation types, Quercus robur–Carex arenaria and Q. robur–Pleurozium schreberi communities, both restricted to the oak dune forest areas in western

  1. Geographic Position of Dunes Relative to the Belet Sand Sea Margins and Correlation with Dune Width and Spacing

    NASA Astrophysics Data System (ADS)

    Bishop, B. B.; Radebaugh, J. R.; Christiansen, E. H.; Lewis, R. C.

    2015-05-01

    Dune width variability in Belet's sand sea decreases with increasing distance to the margin. Distinct groups of width data at 100 km intervals from the sand sea margin showed a decreasing standard deviation with increasing distance from the margin.

  2. Toll-Like Receptor 4 Stimulation Triggers Crescentic Glomerulonephritis by Multiple Mechanisms Including a Direct Effect on Renal Cells

    PubMed Central

    Giorgini, Angela; Brown, Heather J.; Sacks, Steven H.; Robson, Michael G.

    2010-01-01

    A role for toll-like receptor 4 (TLR4) has been suggested in previous studies of glomerulonephritis, but the complex integration of these effects has not been explored. To separate effects on the innate and adaptive immune responses, we use the autologous nephrotoxic nephritis model with two disease induction protocols. First, we give a TLR4 ligand at the time of immunization and show the effects are mediated via TLR4 by comparing wild-type and TLR4-deficient mice. In wild-type mice histological measures of disease and serum creatinine are all at least twice as high as TLR4-deficient mice, due to an enhanced immune response to the nephritogenic sheep IgG. Second, we stimulate TLR4 later in the course of disease development and construct four groups of bone marrow chimeric or sham chimeric mice to study the role of TLR4 on bone marrow or renal cells. The most striking finding is that renal cell TLR4 stimulation increases glomerular crescent formation, with a mean of 21% and 25% in the two groups of mice with renal cell TLR4 compared with 0.1% and 0.6% in the two groups without, with differences mirrored by changes in serum creatinine. These findings, in a single disease model, illustrate that TLR4 stimulation triggers crescentic glomerulonephritis by effects on both the adaptive and innate immune response, with a crucial direct effect on renal cells. PMID:20566738

  3. A case of elderly-onset Crescentic Henoch-Schönlein purpura nephritis with hypocomplementemia and positive MPO-ANCA.

    PubMed

    Yu, Jung-Hee; Lee, Kyu-Beck; Lee, Jae Eun; Kim, Hyang; Kim, Kyungeun; Jang, Ki-Seok; Park, Moon Hyang

    2012-08-01

    Henoch-Schönlein purpura (HSP) is common in childhood and often self-limiting. There have been limited studies on elderly-onset HSP nephritis (HSPN). A 76-yr-old man was transferred to our hospital with a 1-month history of oliguria, abdominal pain, edema and palpable purpura in the legs. Three months ago, he was admitted to another hospital with jaundice, and consequently diagnosed with early common bile duct cancer. The patient underwent a Whipple's operation. Antibiotics were administrated because of leakage in the suture from the surgery. However, he showed progressive renal failure with edema and purpura in the legs. Laboratory investigations showed serum creatinine 6.4 mg/dL, 24-hr urine protein 8,141 mg/day, myeloperoxidase anti-neutrophil cytoplasmic antibodies (MPO-ANCA) 1:40 and C(3) below 64.89 mg/dL. Renal biopsy showed crescentic glomerulonephritis, as well as mesangial and extracapillary Ig A deposition. We started steroid therapy and hemodialysis, but he progressed to end-stage renal failure and he has been under maintenance hemodialysis. We describe elderly onset HSPN with MPO-ANCA can be crescentic glomerulonephritis rapidly progressed to end stage renal failure. PMID:22876066

  4. Large Eddy Simulation of Flow and Sediment Transport over Dunes

    NASA Astrophysics Data System (ADS)

    Agegnehu, G.; Smith, H. D.

    2012-12-01

    Understanding the nature of flow over bedforms has a great importance in fluvial and coastal environments. For example, a bedform is one source of energy dissipation in water waves outside the surf zone in coastal environments. In rivers, the migration of dunes often affects the stability of the river bed and banks. In general, when a fluid flows over a sediment bed, the sediment transport generated by the interaction of the flow field with the bed results in the periodic deformation of the bed in the form of dunes. Dunes generally reach an equilibrium shape, and slowly propagate in the direction of the flow, as sand is lifted in the high shear regions, and redeposited in the separated flow areas. Different numerical approaches have been used in the past to study the flow and sediment transport over bedforms. In most research works, Reynolds Averaged Navier Stokes (RANS) equations are employed to study fluid motions over ripples and dunes. However, evidences suggests that these models can not represent key turbulent quantities in unsteady boundary layers. The use of Large Eddy Simulation (LES) can resolve a much larger range of smaller scales than RANS. Moreover, unsteady simulations using LES give vital turbulent quantities which can help to study fluid motion and sediment transport over dunes. For this steady, we use a three-dimensional, non-hydrostatic model, OpenFOAM. It is a freely available tool which has different solvers to simulate specific problems in engineering and fluid mechanics. Our objective is to examine the flow and sediment transport from numerical stand point for bed geometries that are typical of fixed dunes. At the first step, we performed Large Eddy Simulation of the flow over dune geometries based on the experimental data of Nelson et al. (1993). The instantaneous flow field is investigated with special emphasis on the occurrence of coherent structures. To assess the effect of bed geometries on near bed turbulence, we considered different dune geometries based on dune height and wave length. We will also examine the role of near bed turbulence on sediment transport over dunes. For validation, profiles of velocities, turbulent intensities, and sediment transport calculated by the numerical model will be compared with available experimental measurements.

  5. Solar radiation, longwave radiation and emergent wetland evapotranspiration estimates from satellite data in Florida, USA \\/ Estimations à partir de données satellitales du rayonnement solaire, du rayonnement de grande longueur d’onde et de l’évapotranspiration d’une zone humide de Floride (EUA)

    Microsoft Academic Search

    Jennifer M. Jacobs; Martha C. Anderson; Lee C. Friess; George R. Diak

    2004-01-01

    Routine estimates of daily incoming solar radiation from the GOES-8 satellite were compared to locally measured values in Florida. Longwave radiation estimates corrected using GOES-derived cloud amount and cloud top temperature products improved net radiation estimates as compared to a clear sky longwave approach. The Penman-Monteith, Turc, Hargreaves and Makkink models were applied using GOES-derived estimates of solar radiation and

  6. Origin and lateral migration of linear dunes in the Qaidam Basin of NW China revealed by dune sediments, internal structures, and optically stimulated luminescence ages, with implications for linear dunes on Titan: discussion

    USGS Publications Warehouse

    Rubin, David M.; Rubin, Alan M.

    2013-01-01

    Zhou et al. (2012) proposed that longitudinal dunes in the Qaidam Basin, China, formed like yardangs: by erosion into sediment that was not deposited by those dunes. Because erosion occurs on the upwind flanks of most migrating dunes (Rubin and Hunter, 1982, 1985), the key to demonstrating a yardang-like origin is to show that the dunes did not deposit the strata that they contain. Zhou et al. made this argument by proposing that: (1) The dunes have not deposited cross-strata in the past 810 yr. (2) Cross-bedding within the dunes was not deposited by the dunes on the present-day land surface, but rather by older dunes that had a different morphology. (3) The present dunes are a later generation, “most likely of erosional origin similar to yardangs with orientations controlled by strikes of joints,” (p. 1147). (4) Rates of deflation in the dune field have been extremely high for the past 810–2440 yr. This commentary reviews these conclusions, reviews contradictory observations, and considers alternative interpretations.

  7. The Mediterranean Coastal Dunes in Egypt: An Endangered Landscape

    NASA Astrophysics Data System (ADS)

    Batanouny, K. H.

    1999-08-01

    The Mediterranean coast in Egypt extends almost 900 km, the major part of which is bordered by sand dunes of different natures and types. Along the coastline between Alexandria and El-Alamein, a distance of some 100 km, the sand dunes represent a particular landscape with special characteristics and features, and consequently plants with particular attributes. In this area, the belt of sand dunes has developed immediately south of the shore and these dunes may rise up to 10 m in height and extend about 0·5-1·5 km inland from the shore. These dunes are famous as a habitat for the fig (Ficus carica L.) cultivation depending on the irregular rainfall. They also represent a landing station and a cross-road for birds such as quail migrating from Europe in the north. In the past, summer resort areas were confined to limited areas with few people, these same areas support the growth of some important plant species, for example, sand binders, medicinal and range plants. For more than two decades, there has been considerable socio-economic change and an open-door policy in the economy of the country has been adopted. One of the consequences of this change is that a great part of the coastal dune belt west of Alexandria till El-Alamein, has been subjected to destruction, due to the continuous construction of summer resort villages. These were built at a distance of about 100 m of the shoreline, extending 400-600 m inland and a breadth of 400 m or more along the shoreline. The area already covered by the dunes is now almost occupied by new buildings, gardens and other infrastructure. The consequences of these human activities are numerous and include impacts on the soil, water resources, the flora and the fauna, migrating birds, trends of the indigenous people, and the cultural environment. The present paper gives a concise environmental setting of the dune belt before the advent of the new activities, and the socio-economic and political attitudes which threaten the dunes. The ecological consequences of the recent human activities and recommendations are presented.

  8. An analysis of the moon's surface using reflected illumination from the earth during a waning crescent lunar phase

    NASA Technical Reports Server (NTRS)

    Hammond, Ernest C., Jr.; Linton-Petza, Maggie

    1989-01-01

    There have been many articles written concerning the lunar after-glow, the spectacular reflection from the moon's surface, and the possible observation of luminescence on the dark side of the moon. The researcher, using a 600 mm cassegrain telescope lense and Kodak 400 ASA T-Max film, photographed the crescent moon whose dark side was clearly visible by the reflected light from earth. The film was digitized to a Perkin-Elmer 1010M microdensitometer for enhancement and enlargement. The resulting pictures indicate a completely different land pattern formation than observed during a full moon. An attempt is made to analyze the observed structures and to compare them to the pictures observed during the normal full moon. There are boundaries on the digitized dark section of the moon that can be identified with structures seen during the normal full moon. But, these variations do change considerably under enhancement.

  9. 44 CFR 65.11 - Evaluation of sand dunes in mapping coastal flood hazard areas.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...Evaluation of sand dunes in mapping coastal flood hazard areas. 65.11 Section 65...INSURANCE AND HAZARD MITIGATION National Flood Insurance Program IDENTIFICATION AND...Evaluation of sand dunes in mapping coastal flood hazard areas. (a) General...

  10. Investigation of Martian Aeolian Dynamics Using Terrestrial Dune Analogues and Airflow Modelling

    NASA Astrophysics Data System (ADS)

    Cornwall, C.; Jackson, D. W. T.; Bourke, M. C.; Cooper, J. A. G.

    2015-05-01

    We combine field observations, 3D computational fluid dynamics modeling and remote sensing data from Mars to constrain grain flow events that occur on lee slopes of dunes to improve estimates of dune field migration and sediment flux on Mars.

  11. 78 FR 11981 - Special Regulations; Areas of the National Park System, Sleeping Bear Dunes National Lakeshore...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-21

    ...Areas of the National Park System, Sleeping Bear Dunes National Lakeshore, Bicycling AGENCY...SUMMARY: This rule designates the Sleeping Bear Heritage Trail currently under construction within Sleeping Bear Dunes National Lakeshore as a route...

  12. 77 FR 62476 - Special Regulations; Areas of the National Park System, Sleeping Bear Dunes National Lakeshore...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-15

    ...Areas of the National Park System, Sleeping Bear Dunes National Lakeshore, Bicycling AGENCY...Service proposes to designate the Sleeping Bear Heritage Trail currently under construction within Sleeping Bear Dunes National Lakeshore as a route...

  13. Advanced InSAR imaging for dune mapping

    NASA Astrophysics Data System (ADS)

    Havivi, Shiran; August, Yitzhak; Blumberg, Dan G.; Rotman, Stanley R.

    2015-04-01

    Aeolian morphologies are formed in the presence of sufficient wind energy and available particles. These processes occur naturally or are further enhanced or reduced by human intervention. The dimensions of change are dependent primarily on the wind energy and surface properties. Since the 1970's, remote sensing imagery both optical and radar, are used for documentation and interpretation of the geomorphologic changes of sand dunes. Remote sensing studies of Aeolian morphologies is mostly useful to document major changes, yet, subtle changes, occurring in a period of days or months in scales of centimeters, are very difficult to detect in imagery. Interferometric Synthetic Aperture Radar (InSAR) is an imaging technique for measuring Earth's surface topography and deformation. InSAR images are produced by measuring the radar phase difference between two separated antennas that view the same surface area. Classical InSAR is based on high coherence between two images or more. The output (interferogram) can show subtle changes with an accuracy of several millimeters to centimeters. Very little work has been done on measuring or identifying the changes in dunes using InSAR. The reason is that dunes tend to be less coherent than firm, stable, surfaces. This research aims to demonstrate how interferometric decorrelation, or, coherence change detection, can be used for identifying dune instability. We hypothesize and demonstrate that the loss of radar coherence over time on dunes can be used as an indication of the dune's instability. When SAR images are acquired at sufficiently close intervals one can measure the time it takes to lose coherence and associate this time with geomorphic stability. To achieve our goals, the Nitzanim coastal dunes along the Mediterranean, 40 km south of Tel-Aviv, Israel, were chosen as a case study. The dunes in this area are of varying levels of stability and vegetation cover and have been monitored meteorologically, geomorphologically and extensively in the field. High resolution TerraSAR-X (TSX) images, covering the entire research area were acquired for the period of October 2011 to July 2012 (15 images in total). All images were co-registreted, the first image was used as the master image. A coherence index was calculated for all the images. Analysis was performed in GIS software. The results display minor changes (coherence index in range of 0.4-0.65) on dune crests depending on the dune location relative to its distance from the sea and distance from the city. In addition, field results indicate erosion / deposition of sand in a cumulatively amount of approximately 30mm annually. The results of this study confirm that it is possible to monitor subtle changes in dunes and to identify dune stability or instability, only by the use of SAR images.

  14. Effects of trampling limitation on coastal dune plant communities.

    PubMed

    Santoro, Riccardo; Jucker, Tommaso; Prisco, Irene; Carboni, Marta; Battisti, Corrado; Acosta, Alicia T R

    2012-03-01

    Sandy coastlines are sensitive ecosystems where human activities can have considerable negative impacts. In particular, trampling by beach visitors is a disturbance that affects dune vegetation both at the species and community level. In this study we assess the effects of the limitation of human trampling on dune vegetation in a coastal protected area of Central Italy. We compare plant species diversity in two recently fenced sectors with that of an unfenced area (and therefore subject to human trampling) using rarefaction curves and a diversity/dominance approach during a two year study period. Our results indicate that limiting human trampling seems to be a key factor in driving changes in the plant diversity of dune systems. In 2007 the regression lines of species abundance as a function of rank showed steep slopes and high Y-intercept values in all sectors, indicating a comparable level of stress and dominance across the entire study site. On the contrary, in 2009 the regression lines of the two fenced sectors clearly diverge from that of the open sector, showing less steep slopes. This change in the slopes of the tendency lines, evidenced by the diversity/dominance diagrams and related to an increase in species diversity, suggests the recovery of plant communities in the two fences between 2007 and 2009. In general, plant communities subject to trampling tended to be poorer in species and less structured, since only dominant and tolerant plant species persisted. Furthermore, limiting trampling appears to have produced positive changes in the dune vegetation assemblage after a period of only two years. These results are encouraging for the management of coastal dune systems. They highlight how a simple and cost-effective management strategy, based on passive recovery conservation measures (i.e., fence building), can be a quick (1–2 years) and effective method for improving and safeguarding the diversity of dune plant communities. PMID:22302225

  15. Effects of Trampling Limitation on Coastal Dune Plant Communities

    NASA Astrophysics Data System (ADS)

    Santoro, Riccardo; Jucker, Tommaso; Prisco, Irene; Carboni, Marta; Battisti, Corrado; Acosta, Alicia T. R.

    2012-03-01

    Sandy coastlines are sensitive ecosystems where human activities can have considerable negative impacts. In particular, trampling by beach visitors is a disturbance that affects dune vegetation both at the species and community level. In this study we assess the effects of the limitation of human trampling on dune vegetation in a coastal protected area of Central Italy. We compare plant species diversity in two recently fenced sectors with that of an unfenced area (and therefore subject to human trampling) using rarefaction curves and a diversity/dominance approach during a two year study period. Our results indicate that limiting human trampling seems to be a key factor in driving changes in the plant diversity of dune systems. In 2007 the regression lines of species abundance as a function of rank showed steep slopes and high Y-intercept values in all sectors, indicating a comparable level of stress and dominance across the entire study site. On the contrary, in 2009 the regression lines of the two fenced sectors clearly diverge from that of the open sector, showing less steep slopes. This change in the slopes of the tendency lines, evidenced by the diversity/dominance diagrams and related to an increase in species diversity, suggests the recovery of plant communities in the two fences between 2007 and 2009. In general, plant communities subject to trampling tended to be poorer in species and less structured, since only dominant and tolerant plant species persisted. Furthermore, limiting trampling appears to have produced positive changes in the dune vegetation assemblage after a period of only two years. These results are encouraging for the management of coastal dune systems. They highlight how a simple and cost-effective management strategy, based on passive recovery conservation measures (i.e., fence building), can be a quick (1-2 years) and effective method for improving and safeguarding the diversity of dune plant communities.

  16. Le groupe SK 2 d'une alg ebre de biquaternions

    E-print Network

    Le groupe SK2 d'une alg`ebre de biquaternions Baptiste Calm`es Equipe de topologie et g'exactitude d'une suite (1) qui relie le groupe SK2 (noyau de la norme r´eduite) d'une alg`ebre de biquaternions topologique d'une quadrique d'Albert. The group SK2 of a biquaternion algebra Abstract In this note, I

  17. Le groupe SK2 d'une alg`ebre de biquaternions Baptiste Calm`es

    E-print Network

    Le groupe SK2 d'une alg`ebre de biquaternions Baptiste Calm`es Equipe de topologie et g'exactitude d'une suite (1) qui relie le groupe SK2 (noyau de la norme r'eduite) d'une alg`ebre de biquaternion filtration topo* *logique d'une quadrique d'Albert. The group SK2 of a biquaternion algebra Abstract

  18. Multifrequency and multipolarization radar scatterometry of sand dunes and comparison with spaceborne and airborne radar images

    Microsoft Academic Search

    Ronald Blom; Charles Elachi

    1987-01-01

    Understanding the unusual radar scattering characteristics of sand dunes is necessary in the analysis of radar images of aeolian landscapes of the earth and of other planets. In this paper we report on airborne radar scatterometer data of sand dunes, acquired at multiple frequencies and polarizations. Radar backscatter from sand dunes is very sensitive to the imaging geometry. At small

  19. Adaptation with gene flow across the landscape in a dune sunflower

    E-print Network

    Rieseberg, Loren

    habitats. This can occur early in the process of adaptive divergence and is a key feature of ecological speciation being driven by the dune habitat. Keywords: divergence with gene flow, ecological speciation in active sand dunes and adjacent non-dune habitat, using landscape genetics approaches, such as circuit

  20. Non-linear and linear wave propagation in booming sand dunes

    Microsoft Academic Search

    Nathalie Vriend; Melany Hunt; Rob Clayton

    2008-01-01

    For centuries booming sand dunes have intrigued travelers and scientists alike. These dunes emit a persistent, low-frequency sound during a slumping event or natural avalanche on the leeward face of the dune. This sound can last for several minutes and be audible for miles. The acoustic emission is characterized by a dominant audible frequency (70 - 105 Hz) and several

  1. DIGITAL PHOTOGRAMMETRIC CHANGE ANALYSIS AS APPLIED TO ACTIVE COASTAL DUNES IN MICHIGAN

    E-print Network

    Brown, Daniel G.

    DIGITAL PHOTOGRAMMETRIC CHANGE ANALYSIS AS APPLIED TO ACTIVE COASTAL DUNES IN MICHIGAN Daniel G COASTAL DUNES IN MICHIGAN Abstract A pilot study was conducted to investigate the applicability of digital sand (i.e., dune fields and sand sheets) easily mobilize when stabilizing vegetation is somehow reduced

  2. AlAbAmA Dune RestoRAtion PRoject General Project DescriPtion

    E-print Network

    , the Coastal Alabama Dune Restoration Cooperative (CADRC), to restore natural resources that were injured habitat by planting native dune vegetation and installing sand fencing. The project will help prevent, the Coastal Alabama Dune Restoration Cooperative (CADRC), to restore natural resources that were injured

  3. Vegetation and ghost crabs in coastal dunes as indicators of putative stressors from tourism

    Microsoft Academic Search

    Thomas A. Schlacher; Rudolf de Jager; Tara Nielsen

    2011-01-01

    Coastal dunes provide important ecosystem services and are susceptible to human disturbance such as vehicle traffic and human trampling. Notwithstanding, on several Australian beaches dunes serves as camping areas, where camping sites are located on the primary dunes landwards of the foredunes. Because these activities have the potential to impact on the biota of the foredunes directly adjoining the camping

  4. Soil nutrients are not responsible for arrested succession in disturbed coastal dune forest

    Microsoft Academic Search

    L. J. Boyes; M. E. Griffiths; A. D. Manson; M. J. Lawes

    2010-01-01

    Coastal dune forest succession frequently proceeds via the Acacia karroo pathway, but may become arrested. We examine whether soil fertility arrests forest succession in A. karroo stands in coastal dune forest in KwaZulu-Natal province, South Africa. We examined soil fertility of A. karroo stands, the adjacent forest, and forested dune slacks at Cape Vidal, and four rehabilitating A. karroo stands

  5. Restoration of lichen diversity in grass-dominated vegetation of coastal dunes after wildfire

    Microsoft Academic Search

    R. Ketner-Oostra; M. J. van der Peijl; K. V. Sýkora

    2006-01-01

    Question: Can lichen diversity of an earlier succession stage be restored in dune grassland after fire in a region with high nitrogen deposition? Location: Calcium-poor coastal dunes in the Wadden district, The Netherlands. Methods: We sampled dune grassland by using a large continuous transect of 4 m x 4 m blocks on both a south slope and a west slope.

  6. Environmental Controls and Eco-geomorphic Interactions of the Barchan-to-parabolic Dune Stabilisation and the Parabolic-to-barchan Dune Reactivation

    NASA Astrophysics Data System (ADS)

    Yan, Na; Baas, Andreas

    2015-04-01

    Parabolic dunes are one of a few common aeolian landforms which are highly controlled by eco-geomorphic interactions. Parabolic dunes, on the one hand, can be developed from highly mobile dune landforms, barchans for instance, in an ameliorated vegetation condition; or on the other hand, they can be reactivated and transformed back into mobile dunes due to vegetation deterioration. The fundamental mechanisms and eco-geomorphic interactions controlling both dune transformations remain poorly understood. To bridge the gap between complex processes involved in dune transformations on a relatively long temporal scale and real world monitoring records on a very limited temporal scale, this research has extended the DECAL model to incorporate 'dynamic' growth functions and the different 'growth' of perennial shrubs between growing and non-growing seasons, informed by field measurements and remote sensing analysis, to explore environmental controls and eco-geomorphic interactions of both types of dune transformation. A non-dimensional 'dune stabilising index' is proposed to capture the interactions between environmental controls (i.e. the capabilities of vegetation to withstand wind erosion and sand burial, the sandy substratum thickness, the height of the initial dune, and the sand transport potential), and establish the linkage between these controls and the geometry of a stabilising dune. An example demonstrates how to use the power-law relationship between the dune stabilising index and the normalised migration distance to assist in extrapolating the historical trajectories of transforming dunes. The modelling results also show that a slight increase in vegetation cover of an initial parabolic dune can significantly increase the reactivation threshold of climatic impact (both drought stress and wind strength) required to reactivate a stabilising parabolic dune into a barchan. Four eco-geomorphic interaction zones that govern a barchan-to-parabolic dune transformation and a parabolic-to-barchan dune transformation have been identified. These zones exhibit different characteristics and dynamics that are sensitive to changes in environmental forces, and can be potentially used as a proxy to monitor the mobility of a dune system.

  7. Definition and origin of the dune-field pattern at White Sands, New Mexico

    NASA Astrophysics Data System (ADS)

    Baitis, Elke; Kocurek, Gary; Smith, Virginia; Mohrig, David; Ewing, Ryan C.; Peyret, A.-P. B.

    2014-12-01

    A LiDAR-derived digital elevation model (DEM) of a representative portion of the White Sands Dune Field, New Mexico, allows for characterization of an unprecedented range of dune-field parameters and serves as a basis for pattern analysis. Dune-field parameters were measured and statistically analyzed for populations of dunes selected at random and occurring along transects. Populations sampled by these two different methods are comparable, but highlight the sensitivity of transect placement in a dune field that has pattern heterogeneity. Based upon coefficients of variation, pattern emerges at White Sands primarily because of a strong fabric of crestline orientation, and secondarily because of the regularity of spacing between dunes of similar shape as defined by sinuosity, height and length. Linear regression of dune parameters shows that dune geometric relationships vary primarily with crestline length, but there is little correlation between other parameters, including dune spacing and height. This result highlights the sensitivity of identifying topographic heterogeneity in a LiDAR-derived DEM, given that mean ratios conform to global averages. Stripping off the dunes in Matlab shows a terraced surface, which is interpreted to represent paleo-shorelines formed during relative still stands in the overall retreat of Lake Otero. Elevated bands of higher, more closely spaced dunes occur just leeward of the paleo-shorelines. A revised model for the White Sands Dune Field consists of the basinward progradation of successive dune-field segments. Each segment is associated with a paleo-shoreline, and consists of an upwind dune ridge, represented by the elevated bands, and a leeward dune field.

  8. Luminescence studies of dunes from North-Eastern Tasmania

    Microsoft Academic Search

    G. A. T. Duller; P. Augustinus

    1997-01-01

    Northern Tasmania has a geographically extensive cover of Quaternary aeolian features and although the morphology and stratigraphy of many of these have been studied it is difficult to assign a reliable chronology because of the lack of material suitable for radiocarbon dating. The dunes are primarily composed of quartz and hence are ideally suited for the application of luminescence dating.

  9. Rivers, Lakes, Dunes, and Rain: Crustal Processes in Titan's

    E-print Network

    Reiners, Peter W.

    Rivers, Lakes, Dunes, and Rain: Crustal Processes in Titan's Methane Cycle Jonathan I. Lunine1-6597/09/0530-0299$20.00 Key Words hydrology, climate, hydrocarbons, atmospheres, planets, clouds Abstract Titan exhibits ample SETTING FOR A METHANE CYCLE ON TITAN Titan is Saturn's largest natural satellite and the second

  10. Fly over of Mars Mesa, Tounge, Dunes, Sasquatch Crater

    NSDL National Science Digital Library

    NASA/Goddard Space Flight Center Scientific Visualization Studio

    This site from NASA's Scientific Visualization Studio features fly overs of Mesa, Tounge, Dunes, and Sasquatch Crater. Data for topography is based on the Mars Orbiting Laser Altimeter (MOLA) with Viking data used for color. Vertical exaggeration is about 300 times.

  11. The comparative diet of three Saharan sand dune skinks

    Microsoft Academic Search

    Omar Attum; Charles Covell; Perri Eason

    2004-01-01

    We compared the diets of the only three sand dune skinks of North Sinai, Chalcides ocellatus, Scincus scincus, and Sphenops sepsoides. Despite our small sample size, we found several interesting trends. Coleoptera was the most common prey order eaten by the skinks, occurring in about 90% of the stomachs for each species of lizard. The other prey orders occurred with

  12. Population biology of salt marsh and sand dune annuals

    Microsoft Academic Search

    A. R. Watkinson; A. J. Davy

    1985-01-01

    Annuals represent a significant component of the vegetation of coastal salt marshes and sand dunes. From many points of view, the two habitats might appear to have little in common. Yet both are characterized by episodes of low water potential, marked spatial and temporal heterogeneity and a zonation which, within certain limits, reflects successional change.

  13. Extension d'une valuation * Michel Vaqui'e

    E-print Network

    Extension d'une valuation * Michel Vaqui'e Abstract We want to determine all the extensions of a valuation of a field K to valuation for a given valuation ~ of K[x], and has shown how we can recover any extension to L

  14. A Chronosequence of Aquatic Macrophyte Communities in Dune Ponds

    Microsoft Academic Search

    Douglas A. Wilcox; Howard A. Simonin

    1987-01-01

    Differences in macrophyte community composition in a chronosequence of spatially separated dune ponds near the south shore of Lake Michigan were examined and related to environmental variables. Five ponds from each of five pond rows were sampled. In each pond, the cover of each plant species and water and sediment depth were sampled using a stratified random design. Radiocarbon dates

  15. Trampling affects the distribution of specialised coastal dune arthropods

    Microsoft Academic Search

    Dries Bontea; Dirk Maes

    2008-01-01

    From a conservation point of view, species’ tolerances towards disturbance are often generalised and lack reference to spatial scales and underlying processes. In order to investigate how average typical species react to habitat fragmentation and disturbance, we adopted a multi-species approach to address occupancy patterns of five specialised dune arthropods (butterflies Hipparchia semele, Issoria lathonia; grasshopper Oedipoda caerulescens; spiders Alopecosa

  16. The Influence of Physical & Biological Cohesion on Dune Development

    NASA Astrophysics Data System (ADS)

    Schindler, Robert; Parsons, Daniel; Ye, Leiping; Baas, Jaco; Hope, Julie; Manning, Andy; Malarkey, Jonathan; Aspden, Rebecca; Lichtman, Dougal; Thorne, Peter; Peakall, Jeff; Patterson, David; Davies, Alan; Bass, Sarah; O'Boyle, Louise

    2014-05-01

    Existing predictions for dune bedforms are based on simplified physical parameters, with assumptions that sediment consists only of cohesionless sand. They do not include the complexities of mud: physical cohesion is imparted by cohesive clays and biological cohesion is created by the presence of organisms which, among other things, generate extra-cellular polymers (EPS). Using controlled experiments we show the profound influence on the size, development and equilibrium morphology of dune bedforms of both physical and biological cohesion. Experiments were completed at the Total Environment Simulator facility at Hull University, UK in a 10 x 2 m channel. A flat sediment bed was laid to 0.15 m depth. A unidirectional flow of 0.25 m depth was passed over the sediment for 10 h. In Phase 1 eight different sand:clay mixes were examined, where clay content was 18.0 - 2.1%. In Phase 2, the same mixtures were used with additions of EPS. A velocity of 0.8 m s-1 was used throughout, corresponding to the dune regime for the selected sand. Bedform development was monitored via ultrasonic ranging transducers, sediment cores and water samples. Phase 1 showed substantial differences in bedform type with clay content, with size inversely related to clay content, e.g. Run 1 (18.0% clay) generated 2D ripples; Run 7 (2.1% clay) generated 3D dunes. Transitional forms, included dunes with superimposed ripples, were present between these extremes. In Phase 2, EPS contents equivalent to only 1/30th of 1% by mass prevented the development of bedforms. Bedforms were generated in sediments with 1/20th and 1/10th of 1%, with an inverse relationship between bedform size and EPS content. Comparison of Phase 1 and Phase 2 runs with equal sand:mud ratios reveals that EPS acts to severely inhibit bedform development compared with the mud-only case. We can conclude that (1) the ripple-dune transition can occur under constant flow conditions, i.e. clay content may dictate bedform type, that (2) EPS can severely constrain the development of bedforms, at masses two orders of magnitude smaller than mud, ultimately preventing their development in conditions that would yield dunes in non-cohesive sands and that (3) biological cohesion appears to be greater than physical cohesion at ratios found in natural estuaries. We can conclude that, if the effects of physical and biological cohesion are not included when they are present, predictive models describing bedform growth, morphological equilibrium and migration will be inaccurate and in many cases misleading.

  17. Landslide Deposits, Cookie Bites, and Crescentic Fracturing Along the Northern Puerto Rico-Virgin Islands Margin: Implications for Potential Tsunamigenesis

    NASA Astrophysics Data System (ADS)

    Hearne, M. E.; Grindlay, N. R.; Mann, P.

    2003-12-01

    The seismogenic North America-Caribbean oblique-slip plate boundary forms the 8-km-deep Puerto Rico trench north of the densely populated islands of Puerto Rico and Virgin Islands (combined population of just over 4 million people). The southern slope of the Puerto Rico trench adjacent to the Puerto Rico-Virgin Islands (PRVI) carbonate platform is characterized by frequent seismicity, rapid trenchward tilting, oversteepened slopes, and mass wasting. We present high-resolution bathymetry, HMR1 sidescan imagery, and single-channel seismic data to document extensive landslide deposits that we infer to have been the result of multiple slide events capable of producing prehistoric tsunamis along the coasts of Puerto Rico and the Virgin Islands. Landslide deposits can be traced upslope to two, 45-55 km-wide arcuate-shaped embayments or "cookie bites" carved out of the PRVI platform. Three-dimensional visualization of the debris field and the slope of the largest of the arcuate-shaped embayments centered at 66° 40' constrain volume removal to 1.1 km3 of the PRVI carbonate platform and underlying volcanic and volcaniclastic basement. Sidescan sonar and single-channel seismic data reveal crescentic cracks in the seafloor of the PRVI platform 35-45 km in length located 35 km offshore the northwestern tip of Puerto Rico. These cracks, interpreted to represent the sites of future breakaway scarps and landslides, are similar in shape and length to the head wall scarps of the amphitheaters to the east. An ˜500 km2 section of the PRVI platform (750 m thick) has begun to detach and slump trenchward along the larger of these cracks. Investigation of the existing arcuate-shaped embayments is essential because massive (tens to hundreds of km3) and instantaneous slope failure has the potential to be tsunamigenic. Puerto Rico and the Virgin Islands were inundated by tsunamis in 1867 (mainly affecting St. Thomas and St. Croix, 7 m of runup, casualties in the hundreds) and 1918 (mainly affecting western and northwestern Puerto Rico; 6 m of runup, 120 casualties). Calculation of the potential volume, runout extent, and triggering mechanisms of past submarine landslides will better constrain the tsunamigenic potential of the newly discovered crescentic faults.

  18. Coastal dune development under natural and human influence on Swina Gate Barrier (Polish coast of Pomeranian Bay)

    Microsoft Academic Search

    Tomasz A. ?abuz

    In present times coastal dunes are rapidly changing by human impact and by waves due to increasing sea level. The most important factors in natural dune development are aeolian processes, dune vegetation cover and wind factor. In Poland different dune development stages affected by every mentioned factor may be studied on Swina Gate Barrier localised on Wolin and Uznam Islands

  19. Dispersal by cattle of salt-marsh and dune species into salt-marsh and dune communities

    Microsoft Academic Search

    J. P. Bakker; L. Gálvez Bravo; A. M. Mouissie

    2008-01-01

    Seed dispersal via ingestion and defecation by large herbivores (endozoochory) plays a potentially important role in structuring plant communities. In the present study we tested whether cattle disperse seeds between different plant communities in a heterogeneous coastal habitat. We surveyed the seed contents of cattle dung collected from two habitat types within a grazing system, one in dunes and the

  20. Evidence for community structure and habitat partitioning in coastal dune stiletto flies at the Guadalupe-Nipomo dunes system, California

    Microsoft Academic Search

    Kevin C. Holston

    2005-01-01

    This study provides empirical evidence for habitat selection by North American species of stiletto flies (Diptera: Therevidae), based on local distributions of adults and immatures, and the first hypothesis of community assemblages proposed for a stiletto fly community. Sites at three localities within the Guadalupe-Nipomo dune system were sampled for stiletto flies in 1997 and 2001 by sifting sand, malaise

  1. Functional Traits Differ between Cereal Crop Progenitors and Other Wild Grasses Gathered in the Neolithic Fertile Crescent

    PubMed Central

    Cunniff, Jennifer; Wilkinson, Sarah; Charles, Michael; Jones, Glynis; Rees, Mark; Osborne, Colin P.

    2014-01-01

    The reasons why some plant species were selected as crops and others were abandoned during the Neolithic emergence of agriculture are poorly understood. We tested the hypothesis that the traits of Fertile Crescent crop progenitors were advantageous in the fertile, disturbed habitats surrounding early settlements and in cultivated fields. We screened functional traits related to competition and disturbance in a group of grass species that were increasingly exploited by early plant gatherers, and that were later domesticated (crop progenitors); and in a set of grass species for which there is archaeological evidence of gathering, but which were never domesticated (wild species). We hypothesised that crop progenitors would have greater seed mass, growth rate, height and yield than wild species, as these traits are indicative of greater competitive ability, and that crop progenitors would be more resilient to defoliation. Our results show that crop progenitors have larger seed mass than wild species, germinate faster and have greater seedling size. Increased seed size is weakly but positively correlated with a higher growth rate, which is primarily driven by greater biomass assimilation per unit leaf area. Crop progenitors also tend to have a taller stature, greater grain yield and higher resilience to defoliation. Collectively, the data are consistent with the hypothesis that adaptations to competition and disturbance gave crop progenitors a selective advantage in the areas surrounding early human settlements and in cultivated environments, leading to their adoption as crops through processes of unconscious selection. PMID:24489941

  2. Disasters, women's health, and conservative society: working in Pakistan with the Turkish Red Crescent following the South Asian Earthquake.

    PubMed

    Miller, Andrew C; Arquilla, Bonnie

    2007-01-01

    In recent years, numerous catastrophic disasters caused by natural hazards directed worldwide attention to medical relief efforts. These events included the: (1) 2003 earthquake in Bam, Iran; (2) 2004 earthquake and tsunami in Southeast Asia; (3) Hurricanes Katrina and Rita in the southern United States in 2005; (4) 2005 south Asian earthquake; and (5) 2006 Indonesian volcanic eruption and earthquakes. Health disparities experienced by women during relief operations were a component of each of these events. This article focuses on the response of the Turkish Red Crescent Society's field hospital in northern Pakistan following the South Asian Earthquake of October 2005, and discusses how the international community has struggled to address women's health issues during international relief efforts. Furthermore, since many recent disasters occurred in culturally conservative South Asia and the local geologic activity indicates similar disaster-producing events are likely to continue, special emphasis is placed on response efforts. Lessons learned in Pakistan demonstrate how simple adjustments in community outreach, camp geography, staff distribution, and supplies can enhance the quality, delivery, and effectiveness of the care provided to women during international relief efforts. PMID:18019091

  3. Functional traits differ between cereal crop progenitors and other wild grasses gathered in the Neolithic fertile crescent.

    PubMed

    Cunniff, Jennifer; Wilkinson, Sarah; Charles, Michael; Jones, Glynis; Rees, Mark; Osborne, Colin P

    2014-01-01

    The reasons why some plant species were selected as crops and others were abandoned during the Neolithic emergence of agriculture are poorly understood. We tested the hypothesis that the traits of Fertile Crescent crop progenitors were advantageous in the fertile, disturbed habitats surrounding early settlements and in cultivated fields. We screened functional traits related to competition and disturbance in a group of grass species that were increasingly exploited by early plant gatherers, and that were later domesticated (crop progenitors); and in a set of grass species for which there is archaeological evidence of gathering, but which were never domesticated (wild species). We hypothesised that crop progenitors would have greater seed mass, growth rate, height and yield than wild species, as these traits are indicative of greater competitive ability, and that crop progenitors would be more resilient to defoliation. Our results show that crop progenitors have larger seed mass than wild species, germinate faster and have greater seedling size. Increased seed size is weakly but positively correlated with a higher growth rate, which is primarily driven by greater biomass assimilation per unit leaf area. Crop progenitors also tend to have a taller stature, greater grain yield and higher resilience to defoliation. Collectively, the data are consistent with the hypothesis that adaptations to competition and disturbance gave crop progenitors a selective advantage in the areas surrounding early human settlements and in cultivated environments, leading to their adoption as crops through processes of unconscious selection. PMID:24489941

  4. Testing the limits of the dune phase-stability diagram: the influence of velocity profile shape on dune morphology

    NASA Astrophysics Data System (ADS)

    Unsworth, C. A.; Parsons, D. R.; Reesink, A. J. H.; McLelland, S.

    2014-12-01

    The past 100 years of research on fluvial dunes and their deposits has produced bedform scaling laws based on flow depth, grain size and flow velocity. Such flow-form-deposit scaling is used ubiquitously for a wide range of paleo-environmental interpretations and in predictions of river bed roughness in floods. Recent research from marine environments, density currents, and fluvial flows with strong secondary circulation shows that these laws are often extrapolated beyond the limits of the original research. In submarine density currents, for example, paleo-hydraulic reconstructions commonly predict dune forming flow conditions, but preserved dune cross strata are rarely found. One particular difference between these geophysical flows is the velocity profile shape and bed shear stress that results. In a series of novel laboratory experiments the shape of the mean downstream velocity profile was systematically altered so the velocity maximum was lowered toward the bed through the addition of roughness elements at the water surface; whilst maintaining flow depth and depth-averaged velocities. This produced velocity profile shapes closer to those in density currents, and open-channel flows with strong secondary circulation. The initial lowering of the velocity maximum position increased dune height and length by 250%. The lowest velocity maximum position produced a stable upper-stage plane bed, whilst predictions based on flow depth and mean velocity remained within the dune regime phase-space. The results therefore demonstrate that the vertical position of the downstream velocity maximum can be a better predictor of equilibrium bedform geometries than flow depth or depth averaged velocity and also highlight that paleo-hydraulic reconstructions need to account for the possible variation in profile shape between geophysical flows. This research improves fundamental understanding of fluvial bedform stability and flow-form-deposit scaling laws for extrapolation into in a broader variety of depositional environments beyond open-channel flows.

  5. Physica A 392 (2013) 45024515 Contents lists available at SciVerse ScienceDirect

    E-print Network

    Ashkenazy, Yossi "Yosef"

    2013-01-01

    dune types including blowouts (trough-shaped depressions formed by wind erosion of a sandy substrate) and parabolic dunes (U shaped vegetated dunes), barchans (active crescentic dunes), transverse dunes (active

  6. Sensitivity of the Automatic Determination of Sand Transport Direction and Rate to Dune Morphology (Invited)

    NASA Astrophysics Data System (ADS)

    Scheidt, S. P.; Lancaster, N.

    2010-12-01

    Measurements of rates of dune migration and sand flux are important to understanding the dynamics of aeolian systems, including sand encroachment, desertification, and response to changes in climate. The recent development of the Coregistration of Optically Sensed Images and Correlation (COSI-Corr) algorithm allows a unique remote-sensing approach for measuring dune migration rates. Fast- and slow-moving dunes have been analyzed by previous researchers using the algorithm, but the technique has mostly been tested on simple dune forms, which lack second-order geomorphic features that might cause errors. Our work tested the algorithm’s sensitivity to different dune types and evaluated the performance of the algorithm by making comparisons to previous studies and manual traces of the dunes in a GIS. Different parameters were chosen when applying the COSI-Corr algorithm, which were set according to the expected magnitude of dune displacement and the dune size with respect to image resolution. The dunes under study were chosen from the Namib Desert in locations where dune migration rates had previously been measured. These areas included (1) barchan dunes in Walvis Bay, (2) linear dunes just south of the Kuiseb River and (3) convoys of barchan dunes in the southern Namib. Orthorectified ASTER data from different dates were used to study the incremental and maximal changes between 1967 and 2009. These and other dune areas were studied to understand how varied geographic conditions (e.g.., the presence of coastlines, topography and background surface reflectance) affect the algorithm results. Walvis Bay dune migration vectors indicate rates between 3 and 30 m/yr to the north-northeast, which compares well to the range of previously reported values (2-27 m/yr). Individual dune migration rates between 1961 and 2005 also compared well to distances measured from dune crests in a GIS. Some vectors are overestimated because of interdune albedo effects, resulting from variable soil moisture. Northerly migration of dunes located along barchan convoys in the Southern Namib Desert was determined to be between 9 and 38 m/yr. This compared well to previously published migration rates of ten individually tracked dunes. Migration rate is found to vary with dune size in this area, although the COSI-Corr results have a number of interpretation challenges because of changes in dune shape. Between 2000 and 2006, the overall displacement of small dunes superimposed on linear dunes is between 3-11 m/yr to the north. Interdune displacement vectors in the linear dune area are noisy, which is probably the result of variable vegetation that causes seasonal differences in albedo. The north-south oriented crestline of the linear dunes changes laterally with season by only a few meters, but the magnitude of seasonal crest movement could not be accurately determined due to the error resulting from image spatial resolution; improved results are expected with accurately orthorectified, high spatial resolution imagery of the dunes.

  7. Dune ages in the sand deserts of the southern Sahara and Sahel

    NASA Astrophysics Data System (ADS)

    Bristow, Charlie; Armitage, Simon

    2015-04-01

    In this paper we aim to document the history of aeolian processes within the southern Sahara as part of the INQUA Dune Atlas. We review available luminescence ages for sand dunes across the southern Sahara and attempt to correlate periods of sand accumulation and to develop an improved understanding of the dune chronology on a regional basis. This was achieved by analysing dune age by country, as well as by latitude and longitude. The results show a very patchy spatial distribution of dune ages with large gaps that encompass some of the largest sand seas. Despite these gaps, some related patterns in dune morphology and stratigraphy appear to be consistent between northern Nigeria and southern Mali where older linear dunes are distinct from younger Late Holocene transverse and barchanoid dunes. Elsewhere in Mauretania linear dunes with different orientations appear to have accumulated at different times, most likely in response to changes in atmospheric circulation. Regional climatic changes are identified where dunes are transgressed by lake deposits within endorehic basins. We identify four locations where dune accumulation is terminated by lacustrine transgressions, two of which, in Lake Chad and the Bodélé Depression, occur shortly after the last glacial maximum (LGM). The third example at Gobiero in Niger occurred later, in the early Holocene, around 8.4 ka and a fourth marks a later transgression of Palaeolake MegaChad after 4.7 ka. Larger-scale latitudinal and longitudinal distributions in dune ages across the southern Sahara do not show any consistent patterns, though this may due to the small sample size relative to the study area. In addition, local variations in external controls such as wind regime, rainfall, vegetation and sand supply need to be considered, sometimes on a site by site basis. Limiting the analysis to dune ages determined using the single-aliquot regenerative-dose (SAR) protocol indicates a lack of dune preservation during the LGM and the Younger Dryas, times associated with increased dust input to the oceans which is assumed to indicate increased aeolian activity. The SAR dune dates suggest that preservation of dunes at the onset of succeeding humid intervals is an important component of the dune record. The most striking examples of this phenomenon occur where dunes are preserved within endorehic basins by lacustrine transgressions.

  8. Late Pleistocene dune construction in the Central Sand Plain of Wisconsin, USA

    USGS Publications Warehouse

    Rawling, J. E., III; Hanson, P.R.; Young, A.R.; Attig, J.W.

    2008-01-01

    Wisconsin's Central Sand Plain east of the Wisconsin River is composed of eolian sand forming high-relief dunes surrounded by sand sheets and scattered low-relief dunes. To establish a maximum age for dune formation, three samples for optical dating were taken from glacial Lake Wisconsin lacustrine sediment that underlies eolian sand. These age estimates range from 19.3 to 13.6ka. Age estimates taken from within or at the base of the dunes range from 14.0 to 10.6ka. Samples taken from < 2m of the ground surface were slightly younger, indicating dunes were stabilized between 11.8 and 5.5ka. The younger ages near the surface of some dunes were most likely the result of pedoturbation or localized problems with applying the optical dating method. The majority of the optical age estimates from dunes (18 of 21) indicated that most of the dunes were active between 14 and 10ka and that most dune activity ended by 10ka. These ages suggest that localized activity on dune crests may have occurred in the Holocene but would have been limited to < 1m of sand accumulation. The timing of dune activity and the lack of any significant Holocene reactivation suggest that dune activation in this setting cannot be attributed solely to changes in aridity. Instead, we attribute dune formation to changes in sediment availability from either sand inputs from the Wisconsin River or the melting of permafrost. ?? 2008 Elsevier B.V. All rights reserved.

  9. Soins primaires des personnes victimes d’une lésion médullaire

    PubMed Central

    McColl, Mary Ann; Aiken, Alice; McColl, Alexander; Sakakibara, Brodie; Smith, Karen

    2012-01-01

    Résumé Objectif Effectuer une étude de la portée des données empiriques, entre 1980 et 2009, concernant les soins primaires aux adultes victimes d’une lésion médullaire (LME). Sources des données Une recension dans des revues révisées par des pairs de1980 à 2009 à l’aide de CINAHL, PubMed-MEDLINE, EMBASE, PsycINFO, Social Sciences Abstracts et Social Work Abstracts. Sélection des études La recherche électronique au moyen de mots-clés a permis de cerner 42 articles sur les soins primaires et les LME. Des critères d’inclusion ont servi à réduire la liste à un ensemble de 21 articles publiés en anglais qui portaient sur un échantillon de plus de 3 et présentaient une analyse empirique. Synthèse Environ 90 % des personnes atteintes d’une LME ont identifié leur médecin de famille comme étant leur docteur habituel; 63 % avaient un spécialiste des LME. Les personnes vivant à long terme avec une LME développent des rubriques complexes pour naviguer dans leurs systèmes de soins de santé personnels. Les données scientifiques ne sont pas unanimes quant à l’efficacité des programmes d’intervention directe pour le maintien de la santé et la prévention des complications à la suite d’une LME. Les données appuient cependant le suivi périodique par une équipe spécialisée et un bilan de santé annuel complet. La recherche fait valoir un fort degré d’uniformité dans l’identification des problèmes les plus courants soulevés par les personnes atteintes d’une LME en soins primaires, dont la plupart concernent l’incapacité, plus précisément les complications secondaires, comme la dysfonction intestinale ou vésicale et la douleur. Il existe aussi de bonnes données probantes à l’effet que de nombreux problèmes de santé généraux exigent de l’attention dans une telle population, comme les problèmes de la densité osseuse, la dépression et les questions entourant la santé sexuelle et la reproduction. Il y a des données de niveaux 4 et 5 concernant des besoins en matière de santé non satisfaits qu’ont des personnes victimes d’une LME vivant dans la communauté. En dépit du fait que les patients atteints d’une LME utilisent beaucoup les soins primaires et les services de santé en général, les données scientifiques font valoir que les besoins de renseignements de ces patients en particulier ne sont pas adéquatement satisfaits. Conclusion Un solide système de soins primaires représente la meilleure assurance de bons résultats sur le plan de la santé et d’une utilisation raisonnable des services de santé chez les personnes victimes d’une LME, notamment un bilan de santé annuel complet, un recours approprié aux autres spécialistes et une attention accordée à l’accessibilité et aux besoins insatisfaits.

  10. Dynamics of Unusual Debris Flows on Martian Sand Dunes

    NASA Technical Reports Server (NTRS)

    Miyamoto, Hideaki; Dohm, James M.; Baker, Victor R.; Beyer, Ross A.; Bourke, Mary

    2004-01-01

    Gullies that dissect sand dunes in Russell impact crater often display debris flow-like deposits in their distal reaches. The possible range of both the rheological properties and the flow rates are estimated using a numerical simulation code of a Bingham plastic flow to help explain the formation of these features. Our simulated results are best explained by a rapid debris flow. For example, a debris flow with the viscosity of 10(exp 2) Pa s and the yield strength of 10(exp 2) Pa can form the observed deposits with a flow rate of 0.5 cu m/s sustained over several minutes and total discharged water volume on the order of hundreds of cubic meters, which may be produced by melting a surface layer of interstitial ice within the dune deposits to several centimeters depth.

  11. Successful treatment with plasma exchange for ANCA-negative pauci-immune crescentic glomerulonephritis with D-negative hemolytic uremic syndrome.

    PubMed

    Irifuku, Taisuke; Naito, Takayuki; Ogawa, Takahiko; Masaki, Takao

    2014-10-01

    Co-existence of antineutrophil cytoplasmic antibody (ANCA)-negative pauci-immune crescentic glomerulonephritis (CGN) and thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTPHUS) is extremely rare and has a poor renal prognosis. We report a 76-year-old female that had both ANCA and anti-human lysosomal membrane protein 2 (LAMP-2) antibody-negative pauci-immune CGN with D-negative HUS. She was admitted with proteinuria and worsening renal failure with massive crescent formation on renal biopsy specimens. We initiated intravenous methylprednisolone pulse therapy followed by oral prednisolone, but she still developed D-negative HUS. We then initiated plasma exchange, which achieved remission of Dnegative HUS and improved renal function. To our knowledge, this is the first report of recovery from renal failure in ANCA-negative pauci-immune CGN with TTP-HUS. PMID:25074840

  12. Simultaneous occurrence of diabetic glomerulosclerosis, IgA nephropathy, crescentic glomerulonephritis, and myeloperoxidase-antineutrophil cytoplasmic antibody seropositivity in a Chinese patient.

    PubMed

    Lui, Sing Leung; Chan, Kwok Wah; Yip, Pok Siu; Chan, Tak Mao; Lai, Kar Neng; Lo, Wai Kei

    2002-10-01

    We report the case of a 72-year-old woman with a long-standing history of diabetes mellitus who presented with heavy proteinuria and rapid deterioration in renal function. She had a high titer of myeloperoxidase-antineutrophil cytoplasmic antibody (MPO-ANCA). The renal biopsy specimen revealed features of diabetic glomerulosclerosis, crescentic glomerulonephritis, and IgA nephropathy. Treatment with steroid and cyclophosphamide resulted in significant improvement in renal function and normalization of MPO-ANCA level. This case highlights the importance of having a high index of suspicion for coexisting glomerulonephritis in diabetic patients presenting with proteinuria. The clinical course of patients with diabetic glomerulosclerosis, IgA nephropathy, crescentic glomerulonephritis, and MPO-ANCA seropositivity seems to resemble that of ANCA-associated, rapidly progressive glomerulonephritis and is potentially amenable to aggressive immunosuppressive therapy. PMID:12324935

  13. Sediment Transport as a Function of Position over Dunes

    NASA Astrophysics Data System (ADS)

    McLean, S. R.; Gary, L.

    2008-12-01

    Natural flows over erodible beds are largely controlled by the character of bedforms such as ripples and dunes. Our ability to predict the characteristics of bedforms ultimately depends on developing accurate relations between the near-bed flow and local sediment transport rates. This is often done by applying well- known algorithms such as those developed by Meyer-Peter and Mueller (MPM), Yalin or Einstein to local conditions over a ripple or dune. Because these equations were developed based on the mean transport under steady conditions, they are not accurate when applied to mean local conditions over a dune. Measurements carried out in the re-circulating flume of the Ocean Engineering Laboratory at UCSB clearly show that the relationship between local transport and near-bed flow is more complex than expressions such as that of MPM would suggest. Non-dimensional plots of transport versus bed shear stress (approximated by measuring the streamwise velocity at 12 mm from the bed and assuming a log profile) first of all indicate that there is no apparent critical shear stress. Secondly the relationship between non-dimensional transport and stress is not a single curve, rather a family of curves that depend on the overall mean flow velocity. This results because mean equations like MPM implicitly assume that the turbulent fluctuations in the flow are proportional to the local shear velocity. In flows over dunes where the flow typically separates, especially near reattachment, the turbulent fluctuations are quite large whereas the mean velocity (and stress) are approximately zero. If a simple equation such as that of MPM is applied to a realistic distribution of near-bed velocities rather than the local mean velocity for different discharges, the result is a suite of curves that better match measured transports.

  14. Seasonality of mycorrhizae in coastal sand dunes of Baja California

    Microsoft Academic Search

    Concepción Sigüenza; Ileana Espejel; Edith B. Allen

    1996-01-01

    Populations of arbuscular mycorrhizal fungi were estimated from spores associated with seven plant species in coastal dunes\\u000a at El Socorro, near Ensenada, Baja California, during six months in 1992. The seasonal patterns of percent root colonization\\u000a were also described in the same species during the wet season (January–March) and the dry season (April–July). Comparisons\\u000a were made between the pioneer species

  15. Soil particle sizes and plant communities on coastal dunes

    Microsoft Academic Search

    Jeom-Sook Lee; Byung-Sun Ihm; Du Sung Cho; Dong-Yeob Son; Jong-Wook Kim

    2007-01-01

    To identify and assess the distribution patterns of coastal dune vegetation along the eastern, southern, and western coasts\\u000a of South Korea, we investigated the plant communities and soil factors at 30 sites. In all, 12 communities on CCA (canonical\\u000a correspondence analysis) Axis 1 and 2 could be arranged into 3 groups: 1 ) 2 communities ofElymus mollis andIschaemum anthephoroides, with

  16. Understorey gaps influence regeneration dynamics in subtropical coastal dune forest

    Microsoft Academic Search

    Megan E. Griffiths; Michael J. Lawes; Zivanai Tsvuura

    2007-01-01

    Dominant understorey species influence forest dynamics by preventing tree regeneration at the seedling stage. We examined\\u000a factors driving the spatial distribution of the monocarpic species Isoglossa woodii, a dominant understorey herb in coastal dune forests, and the effect that its cover has on forest regeneration. We used line\\u000a transects to quantify the area of the forest understorey with I. woodii

  17. Coastal sand dune vegetation: An extreme case of species invasion

    Microsoft Academic Search

    S. A. Castillo; P. Moreno-Casasola

    1996-01-01

    The coastal sand-dune flora of the Gulf and Caribbean region of Mexico was analyzed to understand differences in floristic\\u000a composition and richness found along the coast. Each of the 655 species reported was classified according to its ecology and\\u000a distribution range by checking herbaria specimens, literature and specialists. Three groups were formed: (a) species with\\u000a predominantly coastal distribution; (b) ruderal

  18. Reticulated Origin of Domesticated Emmer Wheat Supports a Dynamic Model for the Emergence of Agriculture in the Fertile Crescent

    PubMed Central

    Civá?, Peter; Ivani?ová, Zuzana; Brown, Terence A.

    2013-01-01

    We used supernetworks with datasets of nuclear gene sequences and novel markers detecting retrotransposon insertions in ribosomal DNA loci to reassess the evolutionary relationships among tetraploid wheats. We show that domesticated emmer has a reticulated genetic ancestry, sharing phylogenetic signals with wild populations from all parts of the wild range. The extent of the genetic reticulation cannot be explained by post-domestication gene flow between cultivated emmer and wild plants, and the phylogenetic relationships among tetraploid wheats are incompatible with simple linear descent of the domesticates from a single wild population. A more parsimonious explanation of the data is that domesticated emmer originates from a hybridized population of different wild lineages. The observed diversity and reticulation patterns indicate that wild emmer evolved in the southern Levant, and that the wild emmer populations in south-eastern Turkey and the Zagros Mountains are relatively recent reticulate descendants of a subset of the Levantine wild populations. Based on our results we propose a new model for the emergence of domesticated emmer. During a pre-domestication period, diverse wild populations were collected from a large area west of the Euphrates and cultivated in mixed stands. Within these cultivated stands, hybridization gave rise to lineages displaying reticulated genealogical relationships with their ancestral populations. Gradual movement of early farmers out of the Levant introduced the pre-domesticated reticulated lineages to the northern and eastern parts of the Fertile Crescent, giving rise to the local wild populations but also facilitating fixation of domestication traits. Our model is consistent with the protracted and dispersed transition to agriculture indicated by the archaeobotanical evidence, and also with previous genetic data affiliating domesticated emmer with the wild populations in southeast Turkey. Unlike other protracted models, we assume that humans played an intuitive role throughout the process. PMID:24312385

  19. Solar Power

    NSDL National Science Digital Library

    Integrated Teaching and Learning Program,

    Students learn about solar energy and how to calculate the amount of solar energy available at a given location and time of day on Earth. The importance of determining incoming solar energy for solar devices is discussed.

  20. Solar Lentigo

    MedlinePLUS

    newsletter | contact Share | Solar Lentigo Information for adults A A A This image displays many solar lentigos due to the patient having many sunburns as a child and teenager. Overview A solar lentigo (plural, solar lentigines), also known as a ...

  1. Morpho-chronology of coastal dunes in Médoc. A new interpretation of Holocene dunes in Southwestern France

    Microsoft Academic Search

    Jean-Pierre Tastet; Nigel I. Pontee

    1998-01-01

    Previous work on the coastal dunes in the Médoc region was carried out by the BRGM [Marionnaud, J.M., 1972. Carte géologique de la France (1\\/50000), Feuille St-Vivien-de-Médoc-Soulac-sur-Mer (729–730), Orléans: BRGM Notice explicative par J. Dubreuilh, J.M. Marionnaud (1973), 45 pp.; Dubreuilh, J., Marionnaud, J.M., 1973. Carte géologique de la France (1\\/50000), Feuille Lesparre-Médoc - Le Junca (753–754), Orléans: BRGM Notice

  2. Reconstructing the geomorphic evolution of large coastal dunes along the southeastern shore of Lake Michigan

    NASA Astrophysics Data System (ADS)

    Arbogast, Alan F.; Hansen, Edward C.; Van Oort, Martin D.

    2002-08-01

    Coastal dunes are common along the eastern shore of Lake Michigan, with the most common being large (>30 m high), parabolic dunes that mantle lake terraces south of Manistee, MI. Although these dunes are an important resource in Michigan, and thus intensely managed by various state agencies, their geomorphic history is poorly understood. This study examines four sites near Holland, MI, through stratigraphic and radiocarbon analyses and is the most detailed geomorphic reconstruction conducted of coastal parabolic dunes in the region. Results from this study could benefit the environmental agencies in their management of the coastal dune ecosystem. Deposition of Eolian sand apparently began ˜5500 cal. years BP (i.e., during the Nipissing high stand). Most (˜75%) dune building occurred between ˜4000 and 2500 cal. years BP but was punctuated by brief periods of stability that resulted in the development of Entisols (A/C horizonation). Entisol burial occurred because the sand supply apparently increased during both the receding and rising lake levels. Subsequently, each dune stabilized for ˜2000 years, allowing the formation of Inceptisols (i.e., A/E/Bs/C horizonation). This interval of dune stability correlates with sites south of Holland and occurred while Lake Michigan fluctuated slowly and the beach potentially prograded. These combined variables of slow fluctuation and potential beach progradation hypothetically protected the dunes from wave erosion. Dunes near Holland became active again ˜1000-500 cal. years BP and grew both vertically and laterally. This activity intensified in the past 500 cal. years BP and hypothetically occurred due to recession of the lake shore such that wave erosion at the modern bluff base resumed. Results from this study indicate that coastal dunes along Lake Michigan are similar to many coastal dunes around the world, including those along the intermediate beaches in SE Australia.

  3. Geomorphic history of low-perched, transgressive dune complexes along the southeastern shore of Lake Michigan

    NASA Astrophysics Data System (ADS)

    Hansen, Edward C.; Fisher, Timothy G.; Arbogast, Alan F.; Bateman, Mark D.

    2010-01-01

    A general geomorphic history of low-perched coastal dunes along southeastern Lake Michigan is developed by combining new chronological data from P.J. Hoffmaster and Warren Dunes State Parks (SP) with published data from Van Buren SP, Silver Lake SP and dunes near Holland, Michigan. Fragmentary evidence of dunes older than 6 ka has been almost obliterated by active dune growth since the mid-Holocene Nipissing transgression of ancestral Lake Michigan. Aeolian activity continued during the drop from peak water levels ˜4.7 ka resulting in broad fields of low dunes. Aeolian activity halted during a period of low lake levels but was renewed with the development of large parabolic dune during the Algoma high-water phase of Lake Michigan at ˜3.2 ka. This was followed by reduced aeolian activity and development of the Holland Paleosol. Subsequent dune remobilization predates European settlement. High lake levels and land use practices cannot completely account for the pattern of aeolian activity which may be affected by changes in storm winds linked to changes in the paths of extratropical cyclones. Dune field morphology depends on the whether the shore is receding, prograding or stable. Simple lake-plain complexes form along receding shorelines where lakefront erosion exposes sediment to aeolian transport, leading to the preservation of a single set of large parabolic dunes migrating eastward with the shoreline. Compound lake-plain complexes form along stable or prograding shorelines. Here progressively younger dune ridges develop and blowouts migrate inland forming overlapping and nested parabolic dunes.

  4. Monitoring and analysis of sand dune movement and growth on the Navajo Nation, southwestern United States

    USGS Publications Warehouse

    Redsteer, Margaret Hiza; Bogle, Rian C.; Vogel, John M.

    2011-01-01

    Recurring drought and rising temperatures have caused reactivation and renewed growth of sand dunes on the lands of the Navajo Nation on the Colorado Plateau. Migrating dunes threaten health, housing, and transportation pathways. U.S. Geological Survey (USGS) scientists are conducting research to better understand the processes of dune growth and movement. This research will provide critical data to the Native peoples of the region in their response to the changing environment.

  5. Changes in landscape and vegetation of coastal dunes in northwest Europe: a review

    Microsoft Academic Search

    Sam Provoost; M. Laurence M. Jones; Sally E. Edmondson

    2011-01-01

    In coastal dunes, landscape changes are a rule, rather than an exception. This paper gives an overview of changes in landscape\\u000a and vegetation with a focus on the past century. The history of dunes is characterised by phases of sand drift, alternated\\u000a with geomorphological stability. The historical development of dune woodland during these stable phases has been documented\\u000a for sites

  6. Contrasting ecology of prograding coastal dunes on the northwest coast of Ireland

    Microsoft Academic Search

    Claire Barrett-Mold; Helene Burningham

    2010-01-01

    This paper examines the influence of dune morphological evolution on plant species diversity and composition on the Magheramore\\u000a dune system, Donegal, north-west Ireland. It aims to demonstrate the need for understanding of local geomorphological factors\\u000a and their affect on ecological processes for the enhanced conservation management of coastal dunes. Vegetation surveys and\\u000a cluster analysis of species associations, in combination with

  7. Luminescence and radiocarbon dating of a dune series at Cape Kiwanda, Oregon, USA

    NASA Astrophysics Data System (ADS)

    Jungner, H.; Korjonen, K.; Heikkinen, O.; Wiedemann, A. M.

    2001-12-01

    The coastal dunes of the Pacific Northwest Coast of North America are dynamic systems in a seemingly constant state of change. The cycles of stabilization and re-activation may be connected to changes in climate. There has been much discussion and speculation about the source of these sands and the timing and nature of the episodic events that have shaped the present dune landscape. Holocene development of these dune systems is based primarily on the evidence of previous and present episodes of stabilization and re-activation. One of the best locations for dating these events is the dune system of Cape Kiwanda, where a parabolic dune is eroding on a broad front making six paleosols visible. Eight sediment samples for OSL analysis were taken from the eroding west face of the parabolic dune at Cape Kiwanda, seven being associated with the six exposed paleosols, and the eighth from the base of the dune. Four wood and/or charcoal samples for radiocarbon dating were taken from the paleosols. OSL dating of separated quartz was done using a single-aliquot regeneration technique. The dates cover a time period from a few hundred to around seven thousand years. Radiocarbon dating of charcoal from paleosol layers embedded in the dunes provided separate time markers. The results from the two dating methods are in agreement and provide valuable information about the dynamics of this coastal dune system.

  8. A second look at western Sinai seif dunes and their lateral migration

    NASA Astrophysics Data System (ADS)

    Rubin, David M.; Tsoar, Haim; Blumberg, Dan G.

    2008-01-01

    Tsoar et al. [Tsoar, H., Blumberg, D.G., Stoler, Y., 2004. Elongation and migration of sand dunes. Geomorphology 57, 293-302.] reported that seif dunes in the western Sinai Desert did not migrate laterally between 1973 and 1999. If the planform sinuosities of the dunes are removed by filtering, spatial averaging, or linear regression, however, it is evident that the dunes did, in fact, migrate laterally roughly 13 m during this 26-year period. The measured migration distance is 1-2 orders of magnitude greater than the rms co-registration error Tsoar et al. determined for the first and last air photos that were used to map the dunes. The western Sinai dunes provide another example demonstrating that linear dunes can migrate laterally, and they illustrate some of the difficulties in documenting systematic lateral motion. Lateral migration of a dune can be important geologically or geomorphologically, even where migration is too slow to detect from repeated topographic surveys. This article explains the wind conditions for the lateral migration of seif dunes in western Sinai and the possible wind occurrences that would not lead to such a migration.

  9. Two independent dune growth mechanisms: from laboratory to landscape-scale experiments

    NASA Astrophysics Data System (ADS)

    Narteau, Clement; Ping, Lv; Courrech Du Pont, Sylvain; Dong, Zhibao; Cascales-Fernandez, Laura; Rodriguez, Sébatien

    2015-04-01

    Using laboratory subaqueous experiments, we show that a single bidirectional flow regime can lead to two different dune orientations depending on sediment availability. The erodibility of the bed selects the overriding mechanism for the formation of dunes. Then, dunes may either (1) increase in height from the destabilization of a sand bed with no restriction in sediment availability or (2) grow by extension away from a localized sand source in zones of low sand availability. These results are used to develop a new set of landscape-scale experiments in the Tengger desert (Inner Mongolia, China). Exposed to bimodal winds, this site is unique because it allows multiparametric analysis of dune morphodynamics in a natural environment (16 hectares) under well-controlled initial and boundary conditions. The orientation of dunes as a function of the wind regime and the coupling between flow and topography are currently investigated in three experiments that provide empirical support for the coexistence of two independent dune growth mechanisms. In both laboratory and landscape scale experiments, we find that dunes that are transport-limited select an orientation that maximizes the normal to crest components of transport. In zones of limited sand supply, dunes elongate in the direction of the resultant sand flux at the crest. We show how these results can be used to quantitatively predicts the orientation of primary and secondary dune patterns in modern terrestrial sand seas but also on Mars and Titan.

  10. Iron mineralogy and bioaccessibility of dust generated from soils as determined by reflectance spectroscopy and magnetic and chemical properties--Nellis Dunes recreational area, Nevada

    USGS Publications Warehouse

    Goldstein, Harland L.; Reynolds, Richard L.; Morman, Suzette A.; Moskowitz, Bruce; Kokaly, Raymond F.; Goossens, Dirk; Buck, Brenda J.; Flagg, Cody; Till, Jessica; Yauk, Kimberly; Berquó, Thelma S.

    2013-01-01

    Atmospheric mineral dust exerts many important effects on the Earth system, such as atmospheric temperatures, marine productivity, and melting of snow and ice. Mineral dust also can have detrimental effects on human health through respiration of very small particles and the leaching of metals in various organs. These effects can be better understood through characterization of the physical and chemical properties of dust, including certain iron oxide minerals, for their extraordinary radiative properties and possible effects on lung inflammation. Studies of dust from the Nellis Dunes recreation area near Las Vegas, Nevada, focus on characteristics of radiative properties (capacity of dust to absorb solar radiation), iron oxide mineral type and size, chemistry, and bioaccessibility of metals in fluids that simulate human gastric, lung, and phagolysosomal fluids. In samples of dust from the Nellis Dunes recreation area with median grain sizes of 2.4, 3.1, and 4.3 micrometers, the ferric oxide minerals goethite and hematite, at least some of it nanosized, were identified. In one sample, in vitro bioaccessibility experiments revealed high bioaccessibility of arsenic in all three biofluids and higher leachate concentration and bioaccessibility for copper, uranium, and vanadium in the simulated lung fluid than in the phagolysosomal fluid. The combination of methods used here to characterize mineral dust at the Nellis Dunes recreation area can be applied to global dust and broad issues of public health.

  11. Urinary Thrombin: A Novel Marker of Glomerular Inflammation for the Diagnosis of Crescentic Glomerulonephritis (Prospective Observational Study)

    PubMed Central

    Kitamoto, Yasunori; Arizono, Kenji; Fukui, Hiroyoshi; Tomita, Kimio; Kitamura, Hiroshi; Taguma, Yoshio; Imamura, Takahisa

    2015-01-01

    Background Crescentic glomerulonephritis (CresGN), an uncommon rapidly progressive disease, is characterized by severe glomerular inflammation with fibrin deposition. The lack of specific CresGN biomarkers delays diagnosis and threatens life. Because fibrin deposits in CresGN glomeruli indicate thrombin generation, we hypothesized that thrombin is excreted in urine and is a specific CresGN biomarker. Methods We measured urinary thrombin activity in 200 untreated patients (17 with CresGN, 183 with primary glomerulonephritis) and controls (8 patients with healed CresGN, 11 with nephrosclerosis, and 10 with tubulointerstitial nephritis, and 66 healthy volunteers). CresGN types included 15 pauci-immune and 2 immune complex. We assessed the diagnostic accuracy of thrombinuria in 169 patients with hematuria and proteinuria. Renal biopsy tissues were immunostained for tissue factor and fibrin. We analyzed the relationship of thrombinuria to plasma thrombin-antithrombin complex, hematuria, proteinuria, glomerular filtration rate, glomerular fibrin deposition, antineutrophil cytoplasmic antibodies (ANCAs), and C-reactive protein (CRP). We studied changes in thrombin activities after glucocorticoid treatment in 12 patients with thrombinuria. Results The highest thrombinuria occurrence was in CresGN (70.6%), followed by membranoproliferative glomerulonephritis (41.7%), IgA nephropathy (9.2%), and acute glomerulonephritis (0%). More than 75% of patients with nonproliferative glomerulonephritis manifested no thrombinuria. No controls had thrombinuria. Thrombinuria showed high CresGN specificity (90.1%) and moderate sensitivity (70.6%) and was detected in 4 of 7 patients with ANCA-negative CresGN. In CresGN, thrombinuria was associated with fibrin deposition in glomerular extracapillary tissue, where monocytes/macrophages expressed tissue factor. Thrombinuria in CresGN was unrelated to plasma thrombin-antithrombin complex, hematuria, proteinuria, glomerular filtration rate, and CRP. After glucocorticoid treatment, thrombinuria in patients with CresGN rapidly disappeared but proteinuria and hematuria persisted. Conclusions Thrombinuria was specific for glomerular inflammation, was unaffected by systemic inflammation or coagulation, and demonstrated good diagnostic accuracy for CresGN including ANCA-negative cases. Thrombinuria measurement may provide risk-free diagnosis and screening for CresGN. PMID:25742509

  12. Post-storm beach and dune recovery: Implications for barrier island resilience

    NASA Astrophysics Data System (ADS)

    Houser, Chris; Wernette, Phil; Rentschlar, Elizabeth; Jones, Hannah; Hammond, Brianna; Trimble, Sarah

    2015-04-01

    The ability of beaches and dunes to recover following an extreme storm is a primary control of barrier island response to sea-level rise and changes in the frequency and/or magnitude of storm surges. Whereas erosion of the beach and dune occurs over hours and days, it can be years to decades before the beach and dune are able to recover to their pre-storm state. As a consequence, there are numerous descriptions of near-instantaneous beach and dune erosion due to storms, the immediate onshore transport of sand, and the initial phases of beach and dune recovery following a storm, but a paucity of data on long-term beach and dune recovery. A combination of previously published data from Galveston Island, Texas and new remotely sensed data from Santa Rosa Island, Florida is used in the present study to quantify the rate of dune recovery for dissipative and intermediate beach types, respectively. Recovery of the dune height and volume on Galveston Island was observed within two years following Hurricane Alicia (1983) and was largely complete within six years of the storm, despite extensive washover. In contrast, the dunes on Santa Rosa Island in Northwest Florida began to recover four years after Hurricane Ivan (2004), and only after the profile approached its pre-storm level and the rate of vegetation recovery (regrowth) was at a maximum. Results show that complete recovery of the largest dunes (in height and volume) will take approximately 10 years on Santa Rosa Island, which suggests that these sections of the island are particularly vulnerable to significant change in island morphology if there is also a change in the frequency and magnitude of storm events. In contrast, the areas of the island with the smallest dunes before Hurricane Ivan exhibited a rapid recovery, but no further growth in profile volume and dune height beyond the pre-storm volume and height, despite continued recovery of the largest dunes to their pre-storm height. A change in storm magnitude and/or frequency is a potential threat to barrier island resilience, particularly for those sections of the island where dune recovery has historically taken the longest time. Further study is required to determine how and why dune recovery varies for the dissipative and intermediate beaches of Galveston Island and Santa Rosa Island, respectively.

  13. Non-climatic signal in ice core records: Lessons from Antarctic mega-dunes

    NASA Astrophysics Data System (ADS)

    Ekaykin, Alexey; Eberlein, Lutz; Lipenkov, Vladimir; Popov, Sergey; Schroder, Ludwig

    2015-04-01

    We present the results of glaciological investigations in the mega-dune area located 30 km to the east from Vostok Station (central East Antarctica) implemented during the 58th and 59th Russian Antarctic Expedition (January 2013 and January 2014). Snow accumulation rate and isotope content (?D and ?18O) were measured along the 2-km profile across the mega-dune ridge accompanied by precise GPS altitude measurements and GPR survey. It is shown that the spatial variability of snow accumulation and isotope content covaries with the surface slope. The accumulation rate regularly changes by 1 order of magnitude within the distance < 1 km, with the reduced accumulation at the leeward slope of the dune and increased accumulation in the hollow between the dunes. At the same time, the accumulation rate averaged over the length of a dune wave (25 mm w.e.) corresponds well with the value obtained at Vostok Station, which suggests no additional wind-driven snow sublimation in the mega-dunes comparing to the surrounding plateau. The snow isotope content is in negative correlation with the snow accumulation, which could be explained by post-depositional snow modification and/or by enhanced redistribution by wind of winter precipitation comparing to summer precipitation. Using the GPR data, we estimated the dune drift velocity (5.5 ± 1.3 m yr-1). The full cycle of the dune drift is thus about 340 years. Since the spatial anomalies of snow accumulation and isotope content are supposed to drift with the dune, an ice core drilled in the mega-dune area would exhibit the non-climatic 340-yr cycle of these two parameters. We made an attempt to simulate a vertical profile of isotope content with such a non-climatic variability in a virtual ice core, using the data on the dune size and velocity. The obtained results are discussed in terms of real ice core data interpretation.

  14. Numerical study of turbulent flow over complex aeolian dune fields: the White Sands National Monument.

    PubMed

    Anderson, William; Chamecki, Marcelo

    2014-01-01

    The structure and dynamics of fully developed turbulent flows responding to aeolian dune fields are studied using large-eddy simulation with an immersed boundary method. An aspect of particular importance in these flows is the downwind migration of coherent motions associated with Kelvin-Helmholtz instabilities that originate at the dune crests. These instabilities are responsible for enhanced downward transport of high-momentum fluid via the so-called turbulent sweep mechanism. However, the presence of such structures and their role in determining the bulk characteristics of fully developed dune field sublayer aerodynamics have received relatively limited attention. Moreover, many existing studies address mostly symmetric or mildly asymmetric dune forms. The White Sands National Monument is a field of aeolian gypsum sand dunes located in the Tularosa Basin in southern New Mexico. Aeolian processes at the site result in a complex, anisotropic dune field. In the dune field sublayer, the flow statistics resemble a mixing layer: At approximately the dune crest height, vertical profiles of streamwise velocity exhibit an inflection and turbulent Reynolds stresses are maximum; below this, the streamwise and vertical velocity fluctuations are positively and negatively skewed, respectively. We evaluate the spatial structure of Kelvin-Helmholtz instabilities present in the dune field sublayer (shear length L(s) and vortex spacing ?(x)) and show that ?(x)=m(dune)L(s), where m(dune)?7.2 in the different sections considered (for turbulent mixing layers, 7

  15. Late Quaternary stratigraphy and geochronology of the western Killpecker Dunes, Wyoming, USA

    USGS Publications Warehouse

    Mayer, J.H.; Mahan, S.A.

    2004-01-01

    New stratigraphic and geochronologic data from the Killpecker Dunes in southwestern Wyoming facilitate a more precise understanding of the dune field's history. Prior investigations suggested that evidence for late Pleistocene eolian activity in the dune field was lacking. However, luminescence ages from eolian sand of ???15,000 yr, as well as Folsom (12,950-11,950 cal yr B.P.) and Agate Basin (12,600-10,700 cal yr) artifacts overlying eolian sand, indicate the dune field existed at least during the latest Pleistocene, with initial eolian sedimentation probably occurring under a dry periglacial climate. The period between ???13,000 and 8900 cal yr B.P. was characterized by relatively slow eolian sedimentation concomitant with soil formation. Erosion occurred between ???8182 and 6600 cal yr B.P. on the upwind region of the dune field, followed by relative stability and soil formation between ???5900 and 2700 cal yr B.P. The first of at least two latest Holocene episodes of eolian sedimentation occurred between ???2000 and 1500 yr, followed by a brief (???500 yr) episode of soil formation; a second episode of sedimentation, occurring by at least ???700 yr, may coincide with a hypothesized Medieval warm period. Recent stabilization of the western Killpecker Dunes likely occurred during the Little Ice Age (???350-100 yr B.P.). The eolian chronology of the western Killpecker Dunes correlates reasonably well with those of other major dune fields in the Wyoming Basin, suggesting that dune field reactivation resulted primarily due to departures toward aridity during the late Quaternary. Similar to dune fields on the central Great Plains, dune fields in the Wyoming Basin have been active under a periglacial climate during the late Pleistocene, as well as under near-modern conditions during the latest Holocene. ?? 2003 University of Washington. All rights reserved.

  16. Dune recovery after storm erosion on a high-energy beach: Vougot Beach, Brittany (France)

    NASA Astrophysics Data System (ADS)

    Suanez, Serge; Cariolet, Jean-Marie; Cancouët, Romain; Ardhuin, Fabrice; Delacourt, Christophe

    2012-02-01

    On 10th March 2008, the high energy storm Johanna hit the French Atlantic coast, generating severe dune erosion on Vougot Beach (Brittany, France). In this paper, the recovery of the dune of Vougot Beach is analysed through a survey of morphological changes and hydrodynamic conditions. Data collection focused on the period immediately following storm Johanna until July 2010, i.e. over two and a half years. Results showed that the dune retreated by a maximum of almost 6 m where storm surge and wave attack were the most energetic. Dune retreat led to the creation of accommodation space for the storage of sediment by widening and elevating space between the pre- and post-storm dune toe, and reducing impacts of the storm surge. Dune recovery started in the month following the storm event and is still ongoing. It is characterised by the construction of "secondary" embryo dunes, which recovered at an average rate of 4-4.5 cm per month, although average monthly volume changes varied from - 1 to 2 m 3.m - 1 . These embryo dunes accreted due to a large aeolian sand supply from the upper tidal beach to the existing foredune. These dune-construction processes were facilitated by growth of vegetation on low-profile embryo dunes promoting backshore accretion. After more than two years of survey, the sediment budget of the beach/dune system showed that more than 10,000 m 3 has been lost by the upper tidal beach. We suggest that seaward return currents generated during the storm of 10th March 2008 are responsible for offshore sediment transport. Reconstitution of the equilibrium beach profile following the storm event may therefore have generated cross-shore sediment redistribution inducing net erosion in the tidal zone.

  17. Relationship between vegetation dynamics and dune mobility in an arid transgressive coastal system, Maspalomas, Canary Islands

    NASA Astrophysics Data System (ADS)

    Hernández-Cordero, Antonio I.; Hernández-Calvento, Luis; Espino, Emma Pérez-Chacón

    2015-06-01

    This paper explores the relationship between vegetation dynamics and dune mobility in an arid transgressive coastal dune system, specifically the dune field of Maspalomas (Gran Canaria, Canary Islands). The aim is to understand the strategies of colonization and survival that plant communities have developed in slacks that face dune advance. The relationship between plant colonization and dune migration was performed by following Tamarix canariensis and Traganum moquinii plants for several years. Morphological data about each individual as well as the distance of each plant to the dune were measured. A study of the colonization patterns developed by T. moquinii, T. canariensis, Cyperus laevigatus and Launaea arborescens communities was performed by analyzing the evolution of consolidated plant patches and adult plants in relation to the dune advance. This was achieved using digital orthophotos and spatial analysis from geographic information systems. Initiation of plant colonization over transgressive dunes occurs on both wet and dry slacks. The results show that both plant colonization and development of adult plants are largely related to dune mobility. Thus, survival of T. moquinii and T. canariensis plants under dune migration conditions is related to both distance to the dune front and plant height at the moment of burial. Distance from the dune front and plant height increases chance of survival. The dynamics of adult plants is also related to dune displacement rates. Thus, each community has different thresholds of resistance to mobility rates. The T. canariensis community withstands average rates higher than 3 m/year. Its arboreal structure allows this species to grow high enough to resist the advance of the dunes and burial. For the T. moquinii community, the population decreases gradually to eventually disappear when dune mobility rates exceed 4 m/year. The C. laevigatus community develops at dune mobility rates lower than 3 m/year, decreasing its surface area at higher rates. The L. arborescens community endures dune migration rates of at least 1.8 m/year. However, different distances between the dune front and the vegetated area also significant factor, because these can compensate for the effects of displacement rates. Thus, the closer a vegetated area is to a dune front, the lower the rates of displacement must be to produce a greater reduction in the surface vegetation. Plant communities present two patterns of plant colonization to resist burial by sand, one vertical and the other horizontal. The horizontal pattern is employed by C. laevigatus and L. arborescens communities and consists of locating new generations of plants in progressive alignment with the dune front migration. The vertical pattern is employed by the T. canariensis community, and consists of increasing the heights of the plants. The T. moquinii community can utilize both patterns because it reacts positively to some degree of burial since it is located in areas where the dunes reach different heights.

  18. Aust. J. Mar. Freshwater Res., 1993, 44, 437-58 Limnological Characteristics of Two Coastal Dune Lakes,

    E-print Network

    Canberra, University of

    lake had higher numbers of the predaceous Chaoborus sp. Lake McKenzie had higher invertebrate densities in leached dunes; 0067-1940/93/030437$10.00 #12;R. H. Norris et al. those in lowland leached dunes; water

  19. ETUDE ET MODELISATION DU COMPORTEMENT ELASTIQUE D'UNE STRUCTURE SANDWICH DE TYPE CARTON ONDULE

    E-print Network

    Paris-Sud XI, Université de

    ETUDE ET MODELISATION DU COMPORTEMENT ELASTIQUE D'UNE STRUCTURE SANDWICH DE TYPE CARTON ONDULE sandwich de type carton ondulé. La démarche adoptée est double. Elle aborde le problème d'une part, d. ABSTRACT The main goal of this study is to determine the homogenised properties of sandwich structure

  20. Le surf au Maroc. Les dterminants d'une ressource politique incertaine

    E-print Network

    Paris-Sud XI, Université de

    1 Le surf au Maroc. Les déterminants d'une ressource politique incertaine Christophe GUIBERT « Surf et politiques publiques au Maroc : les déterminants d'une ressource politique incertaine », Sciences Maroc lors d'enquêtes menées en 2002 et 2003. Alors que le sport est en France une ressource politique

  1. CARTS ENTRE PRIX D'ACHAT ET PRIX DE VENTE D'UNE VARIABLE ALATOIRE

    E-print Network

    Boyer, Edmond

    ÉCARTS ENTRE PRIX D'ACHAT ET PRIX DE VENTE D'UNE VARIABLE ALÉATOIRE : UNE CLARIFICATION Jean'autre part la disparité entre le prix d'achat et le prix de vente d'une variable aléatoire. Les résultats que prix distincts peuvent être attachés à une même variable aléatoire : le prix qu'un décideur est prêt à

  2. Global mapping and characterization of Titan's dune fields with Cassini: Correlation between RADAR and VIMS observations

    E-print Network

    Narteau, Clément

    Global mapping and characterization of Titan's dune fields with Cassini: Correlation between RADAR dunes have been observed in the equatorial regions of Titan, Saturn's largest moon. As the Cassini in the examination of their properties. In this paper, we present the joint analysis of Cassini's microwave

  3. Cassini SAR, radiometry, scatterometry and altimetry observations of Titan's dune fields

    E-print Network

    Mojzsis, Stephen J.

    Cassini SAR, radiometry, scatterometry and altimetry observations of Titan's dune fields A. Le Gall. Farr a , the Cassini Radar Team a Jet Propulsion Laboratory, California Institute of Technology, 4800 regions. As the Cassini mission continues, more dune fields are becoming unveiled and examined

  4. Non-target effects of invasive species management: beachgrass, birds, and bulldozers in coastal dunes

    E-print Network

    ; Ammophila breviligulata; beachgrass; Charadrius alexandrinus nivosus; coastal dune; ecosystem engineer. As a result, the critical open-sand habitat of the federally threatened Western Snowy plover (Charadrius alexandrinus nivosus) has declined along with populations of several native dune plant species. Here we

  5. Quantifying Landscape \\/ Ecological Succession in a Coastal Dune System Using Sequential Aerial Photography and GIS

    Microsoft Academic Search

    S. Shanmugam; M. Barnsley

    This chapter presents an attempt to measure the path of habitat and vegetation succession in a coastal dune system (Kenfig NNR, south Wales) using remote sensing and GIS. The loss of slack habitats associated with the continuing stabilization of this dune system is a major cause for concern. These habitats support a range of plant species, including the rare fen

  6. In rivers, ripples and dunes are patterns at two well-separated wavelengths , that are respectively

    E-print Network

    Claudin, Philippe

    In rivers, ripples and dunes are patterns at two well-separated wavelengths , that are respectively are much shorter than those of the bedform growth, the under- standing of pattern formation in rivers can role of the free surface, we evidence that river dunes can not form from a linear instability. Finally

  7. Response of soil microfauna to organic fertilisation in sandy virgin soils of coastal dunes

    Microsoft Academic Search

    Richard Verhoeven

    2001-01-01

    In young white-dune soils with a very low content of organic matter, the influence of organic fertilisation on microfauna, ciliates and nematodes, was investigated. Three fertilisers - straw, rabbit dung, and wheat bran - were added to the soil in order to mimic natural conditions in older dunes. Abundances of nematodes and ciliates were significantly increased with respect to controls,

  8. Dveloppement et intgration d'une antenne relais GSM/3G dans un chargeur inductif

    E-print Network

    Dobigeon, Nicolas

    Développement et intégration d'une antenne relais GSM/3G dans un chargeur inductif Objectif du stage: intégration d'une antenne relais GSM/3G dans un chargeur inductif Lieu du stage: CONTINENTAL et état de l'art sur les systèmes relais GSM/3G: relais analogique par couplage en champ

  9. Ecological study of pine forest clearings along the French Atlantic sand dunes: Perspectives of restoration

    NASA Astrophysics Data System (ADS)

    Lemauviel, Servane; Roze, Françoise

    2000-05-01

    The 18th century afforestation campaign carried out in western France to fix sand dunes has left only a small surface of non-forested dunes. As dune plantations have only a small conservation value, it would be of great interest to restore grey dunes. But, for the moment, there is no proof that pine felling would lead to grey dunes. So, a study has been carried out on pine forest clearings along the French Atlantic shoreline. Floral and ecological data were carried out and analysed with two statistical tools, CA (canonical analysis) and CCA (canonical correspondence analysis). The clearings appear very different from one bank of the Gironde river to the other. South of the river, the clearing vegetation develops on acid soils and possess some thermophilous species. North of the river, the clearings are composed mostly of species growing best on calcareous soils. Apart from geographical variations, clearings showed two patterns of response: development of closed thickets and tall heathlands; or an open vegetation similar to growing heathlands and grasslands. The cover, the height, the floral richness per strata as well as pedological characteristics are the parameters which explain the best floristic composition of pine clearings. The vigour of pine forests and the degree of exposure to coastal influences determine whether close or open vegetation develops. Where there is an open vegetation, restoration of grey dunes may be possible. In the other case, alternative solutions, such as the restoration of dune woodlands or dune heath, may provide best conservation values.

  10. MESURE DE LA TEMPRATURE DES NEUTRONS DANS LE RFLECTEUR D'UNE PILE A EAU LOURDE

    E-print Network

    Boyer, Edmond

    580 MESURE DE LA TEMPÉRATURE DES NEUTRONS DANS LE RÉFLECTEUR D'UNE PILE A EAU LOURDE Par A. ERTAUD neutrons dans le réflecteur de la pile de Châtillon en mesurant la transmission d'une couche d'absorbeurs I/03BD.Le spectre des neutrons est supposé maxwellien. On détermine l'énergie à partir de laquelle

  11. Very large dune formation along the Ebro outer continental shelf (Western Mediterranean)

    Microsoft Academic Search

    Claudio Lo Iacono; Jorge Guillén; Pere Puig; Marta Ribó; Maria Ballesteros; Albert Palanques; Marcelli Farrán; Juan Acosta

    2010-01-01

    Large and very large subaqueous dunes have been observed in a number of outer shelf regions around the world, tipically developing on fossil sand bodies and ridges. Dunes observed on outer shelves usually display large dimensions with maximum wavelength reaching up to 500 m and heights up to 20 m. Forcing mechanisms able to induce their formation have been described

  12. Ontologie de perception des paysages Construction semi-automatique d'une

    E-print Network

    Paris-Sud XI, Université de

    Ontologie de perception des paysages Construction semi-automatique d'une ontologie de la perception conception d'une ontologie axée « perception par les populations » en exploitant les aspects perceptifs'Europe, 2000) et la perception doit être incluse dans la carac- térisation des paysages. hal-00920722,version1

  13. Climbing and falling dunes in Valles Marineris, Mars Matthew Chojnacki,1

    E-print Network

    Perfect, Ed

    Click Here for Full Article Climbing and falling dunes in Valles Marineris, Mars Matthew Chojnacki. Newly acquired Mars Reconnaissance Orbiter (MRO) images and topography of the walls of Valles Marineris, and D. M. Burr (2010), Climbing and falling dunes in Valles Marineris, Mars, Geophys. Res. Lett., 37, L

  14. A numerical study of turbulent flow over complex aeolian dune fields: the White Sands National Monument

    NASA Astrophysics Data System (ADS)

    Anderson, William; Chamecki, Marcelo; Kocurek, Gary; Mohrig, David

    2013-11-01

    The structure and dynamics of fully-developed turbulent flows responding to aeolian dune fields are studied using large-eddy simulation with an immersed boundary method. An aspect of particular importance in these flows is the downwind migration of coherent motions associated with Kelvin-Helmholtz instabilities which originate at the dune crests. These instabilities are responsible for enhanced downward transport of high momentum fluid via the so-called turbulent sweep mechanism. However, the presence of such structures and their role in determining the bulk characteristics of fully developed dune field sublayer aerodynamics has received relatively limited attention. Moreover, many existing studies address mostly symmetric or mildly asymmetric dune forms. The White Sands National Monument is a field of aeolian gypsum sand dunes in southern New Mexico. In the dune field sublayer, the flow statistics resemble a mixing layer: at approximately the dune crest height, vertical profiles of streamwise velocity exhibit an inflection and turbulent Reynolds stresses are maximum; below this, the streamwise and vertical velocity fluctuations are positively and negatively skewed, respectively. We evaluate the spatial structure of Kelvin-Helmholtz instabilities present in the dune field sublayer - shear length, Ls, and vortex spacing, Lambda_x - and show that Ls = m Lambda_x, where m is approximately 8 in the different sections considered.

  15. Large-eddy Simulation of Boundary Layer Flow over Desert Sand Dune Structures

    NASA Astrophysics Data System (ADS)

    Uhlrich, S.; Anderson, W.; Passalacqua, P.; Mohrig, D. C.; Kocurek, G.

    2012-12-01

    Complex spatiotemporal coupling exists between desert sand dune topography and surface layer physics of the atmospheric boundary layer (ABL). Although the interactions of individual desert sand dunes have been extensively studied, with categorical interaction mechanisms identified, the aero-mechanical coupling associated with these dune interactions remains an open problem. Large-eddy simulation (LES) is used to simulate turbulent boundary layer flow over dune structures from White Sands, NM. The dunes are resolved with an immersed boundary method (IBM). The flow-forcing (imposed pressure gradient) is varied to simulate the three common prevailing wind conditions at White Sands (southwest, southeast, and northwest, with southwest being the most common). In the present research, comparison between flow statistics (dune wall pressure distribution retrieved from the IBM) and time-difference dune elevation data are used to characterize the mechanisms responsible for erosion (stoss side) and deposition (lee side) of sand. Additionally, statistical details of time series of aerodynamic forcing at different locations on the dune face are evaluated, which may be used to deepen understanding of erosion and deposition events observed in the time-difference lidar data.

  16. Techniques for GIS modeling of coastal dunes Brian D. Andrews a,*, Paul A. Gares b

    E-print Network

    Thaxton, Christopher S.

    , digital elevation models (DEM) or two-dimensional cross-sections of the dune system. The grid from the MayTechniques for GIS modeling of coastal dunes Brian D. Andrews a,*, Paul A. Gares b , Jeffrey D site on the Outer Banks of North Carolina were assessed through a series of monthly field surveys

  17. Classification and ordination of coastal sand dune vegetation along the Gulf and Caribbean Sea of Mexico

    Microsoft Academic Search

    Patricia Moreno-Casasola I; Ileana Espejel

    1986-01-01

    A classification is presented of community types found in the coastal sand dune systems along the Gulf coast and the Caribbean Sea of Mexico. Twenty-eight dune systems were sampled along transects using the Braun-Blanquet approach. A total of 4444 relevés were subjected to agglomerative classification and table arrangement (program TABORD). Synoptic species values were calculated for the 396 clusters obtained.

  18. Sleeping Bear Dunes National Park Service U.S. Department of the Interior

    E-print Network

    Isaacs, Rufus

    Sleeping Bear Dunes National Park Service U.S. Department of the Interior Sleeping Bear Dunes program. Plants Interns work on controlling invasive plant species, site restoration, re-vegetation, data and cultural landscapes, assists in drafting and developing design plans for the rehabilitation

  19. Coastal dunes as important strongholds for the survival of the rare Niobe fritillary ( Argynnis niobe )

    Microsoft Academic Search

    Alexander Salz; Thomas Fartmann

    2009-01-01

    We studied the oviposition and larval habitat preferences of the Niobe fritillary (Argynnis niobe) in the dunes of the east Frisian Island Langeoog (German North Sea). By ascertaining habitat quality we are able to assess\\u000a the minimum habitat size for populations of A. niobe in dune islands. The preferred oviposition and larval habitats were best characterised by a combination of

  20. La prospective territoriale, rvlateur et outil d'une action publique territorialise

    E-print Network

    Paris-Sud XI, Université de

    La prospective territoriale, révélateur et outil d'une action publique territorialisée dans ce cadre d'interroger l'émergence d'une prospective territoriale locale. Celle-ci constitue en'intervention publique sur les territoires. La prospective suppose en effet l'articulation entre un savoir technique et

  1. Analysis of coastal dune dynamics, shoreline position, and large woody debris at Wickaninnish

    E-print Network

    debris (LWD) and colonizing vegetation alter the sediment budgets and stability of coastal dune systemsAnalysis of coastal dune dynamics, shoreline position, and large woody debris at Wickaninnish Bay. In British Columbia, LWD on beaches consists largely of historical escape logs from the coastal logging

  2. Quantifying vegetation and geomorphic patterns within nebkha dune fields using terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Nield, Joanna; Gillies, John; Nickling, William

    2014-05-01

    Vegetation and sand in semi-arid and coastal sediment starved environments typically interact and form nebkha dunes. We examine the typical dune and vegetation patterns that form with varying amounts of sediment availability and nebkha maturity at Jornada in the Chihuahuan Desert, New Mexico, USA using terrestrial laser scanning (TLS) to separate the plant and sand elements. Manual and automated TLS shrub height extractions compare well at all sites (p=0.48-0.94) enabling the quantification of both solid and plant roughness element components. We find that there is a switch in orientation of the dune elements with respect to dominant wind direction from perpendicular to parallel as the landscape develops from an incipient to mature configuration and mesquite-nebkha streets are enhanced. As the nebkha dunes develop the surface coverage of bare sand increases and dune surfaces exceed the size of their companion shrubs. Roughness density also increases at the mature dune site. Over a three year period up to 20cm of erosion was measured on the upwind faces of the mature nebkha dunes, in agreement with the dominant annual wind direction. However, deposition patterns were more diffuse and influenced by the vegetation patterns. TLS is a useful tool for examining complex sand-vegetation interactions and dune field development.

  3. The Influence of Complex Systems Interactions on Barrier Island Dune Vegetation Pattern and Process

    Microsoft Academic Search

    J. Anthony Stallins; Albert J. Parker

    2003-01-01

    Studies of dune vegetation patterns have emphasized two structuring agents: local environmental gradients that shape the prominent zonation of coastal plant species, and disturbance patches initiated by overwash during coastal storms. For dune systems of two barrier islands in the Georgia Bight, we investigate how the interplay of these two conceptual frames generate patterns in (1) longitudinal (along-shore) and transverse

  4. Community complexity: Stratifying monitoring schemes within a desert sand dune landscape

    Microsoft Academic Search

    C. W. Barrows; M. F. Allen

    2007-01-01

    Landscapes of desert sand dunes are sometimes viewed as biologically and ecologically homogeneous, yet they can be deceptively complex. We analysed temporal and spatial patterns of species occurrence across a desert dune landscape to clarify the utility of a priori community divisions and how those designations facilitate evaluations of whether conservation objectives are being met, and whether adaptive management approaches

  5. A legacy of divergent fishery management regimes and the resilience of rainbow and cutthroat trout populations in Lake Crescent, Olympic National Park, Washington

    USGS Publications Warehouse

    Brenkman, Samuel J.; Duda, Jeffrey J.; Kennedy, Philip R.; Baker, Bruce M.

    2014-01-01

    As a means to increase visitation, early fisheries management in the National Park Service (NPS) promoted sport harvest and hatchery supplementation. Today, NPS management objectives focus on the preservation of native fish. We summarized management regimes of Olympic National Park's Lake Crescent, which included decades of liberal sport harvest and hatchery releases of 14.3 million salmonids. Notably, nonnative species failed to persist in the lake. Complementary analyses of annual redd counts (1989–2012) and genetics data delineated three sympatric trout (one rainbow; two cutthroat) populations that exhibited distinct spatial and temporal spawning patterns, variable emergence timings, and genetic distinctiveness. Allacustrine rainbow trout spawned in the lake outlet from January to May. Cutthroat trout spawned in the major inlet tributary (Barnes Creek) from February to June and in the outlet river (Lyre) from September to March, an unusual timing for coastal cutthroat trout. Redd counts for each species were initially low (rainbow = mean 89; range 37–159; cutthroat = mean 93; range 18–180), and significantly increased for rainbow trout (mean 306; range 254–352) after implementation of catch-and-release regulations. Rainbow and cutthroat trout reached maximum sizes of 10.4 kg and 5.4 kg, respectively, and are among the largest throughout their native ranges. Morphometric analyses revealed interspecific differences but no intraspecific differences between the two cutthroat populations. Genetic analyses identified three distinct populations and low levels (9–17%) of interspecific hybridization. Lake Crescent rainbow trout were genetically divergent from 24 nearby Oncorhynchus mykiss populations, and represented a unique evolutionary legacy worthy of protection. The indigenous and geographically isolated Lake Crescent trout populations were resilient to overharvest and potential interactions with introduced fish species.

  6. A Comparison of Methods Used to Estimate the Height of Sand Dunes on Mars

    NASA Technical Reports Server (NTRS)

    Bourke, M. C.; Balme, M.; Beyer, R. A.; Williams, K. K.; Zimbelman, J.

    2006-01-01

    The collection of morphometric data on small-scale landforms from other planetary bodies is difficult. We assess four methods that can be used to estimate the height of aeolian dunes on Mars. These are (1) stereography, (2) slip face length, (3) profiling photoclinometry, and (4) Mars Orbiter Laser Altimeter (MOLA). Results show that there is good agreement among the methods when conditions are ideal. However, limitations inherent to each method inhibited their accurate application to all sites. Collectively, these techniques provide data on a range of morphometric parameters, some of which were not previously available for dunes on Mars. They include dune height, width, length, surface area, volume, and longitudinal and transverse profiles. Thc utilization of these methods will facilitate a more accurate analysis of aeolian dunes on Mars and enable comparison with dunes on other planetary surfaces.

  7. Vegetation and substrate properties of aeolian dune fields in the Colorado River corridor, Grand Canyon, Arizona

    USGS Publications Warehouse

    Draut, Amy E.

    2011-01-01

    This report summarizes vegetation and substrate properties of aeolian landscapes in the Colorado River corridor through Grand Canyon, Arizona, in Grand Canyon National Park. Characterizing these parameters provides a basis from which to assess future changes in this ecosystem, including the spread of nonnative plant species. Differences are apparent between aeolian dune fields that are downwind of where modern controlled flooding deposits new sandbars (modern-fluvial-sourced dune fields) and those that have received little or no new windblown sand since river regulation began in the 1960s (relict-fluvial-sourced dune fields). The most substantial difference between modern- and relict-fluvial-sourced aeolian dune fields is the greater abundance of biologic soil crust in relict dune fields. These findings can be used with similar investigations in other geomorphic settings in Grand Canyon and elsewhere in the Colorado River corridor to evaluate the health of the Colorado River ecosystem over time.

  8. Speculation on Martian north polar wind circulation and the resultant orientations of polar sand dunes

    NASA Astrophysics Data System (ADS)

    Ward, A. W.; Doyle, K. B.

    1983-09-01

    When seen at frost cap minimum, Martian north polar erg dunes north of 80 deg N record east winds, while those south of that latitude record west winds. Many of the transverse dunes are considered to be reversing dunes, and dunes in the two fields may have reversed at least once during the lifetime of the Viking Orbiters. It is proposed that the average polar winds are strong, off-pole northwest winds in the fall, moderate west winds in winter, latitude-dependent weak-to-strong off-pole northeast winds in spring, and weak west winds in summer, as has been largely confirmed by Viking images of near polar clouds. Over millenia, the combination of reversing west and east winds could produce the biomodal distributions of dune orientations observed at the north pole.

  9. Parabolic dunes and their transformations under environmental and climatic changes: Towards a conceptual framework for understanding and prediction

    NASA Astrophysics Data System (ADS)

    Yan, Na; Baas, Andreas C. W.

    2015-01-01

    The formation and evolution of parabolic aeolian dunes depend on vegetation, and as such are particularly sensitive to changes in environmental controls (e.g., temperature, precipitation, and wind regime) as well as to human disturbances (e.g., grazing, agriculture, and recreation). Parabolic dunes can develop from the stabilisation of highly mobile barchan dunes and transverse dunes as well as from blowouts, as a consequence of colonisation and establishment of vegetation when aeolian sand transport is reduced and/or when water stress is relieved (by increasing precipitation, for instance). Conversely, existing parabolic dunes can be activated and may be transformed into barchan dunes and/or transverse dunes when vegetation suffers environmental or anthropogenic stresses. Predicted increases in temperature and drought severity in various regions raise concerns that dune activation and transformations may intensify, and this intensification would have far-reaching implications for environmental, social, and economic sustainability. To date, a broad examination of the development of parabolic dunes and their related transformations across a variety of climate gradients has been absent. This paper reviews existing literature, compares data on the morphology and development of parabolic dunes in a comprehensive global inventory, and scrutinises the mechanisms of different dune transformations and the eco-geomorphic interactions involved. This knowledge is then integrated into a conceptual framework to facilitate understanding and prediction of potential aeolian dune transformations induced by changes in environmental controls and human activities. This conceptual framework can aid judicious land management policies for better adaptations to climatic changes.

  10. Insights from a Geophysical and Geomorphological Mars Analog Field Study at the Great Kobuk Sand Dunes, Northwestern Alaska

    E-print Network

    Stillman, David E.

    understanding of the processes by which planetary dunes form and evolve. Selected terrestrial analogs are often warm-climate dune fields devoid of frozen volatiles, but cold-climate dunes offer a better analog from 33 to 170 m above mean sea level, consists of sand sheets as well as climbing and reversing

  11. Solar Cookers.

    ERIC Educational Resources Information Center

    King, Richard C.

    1981-01-01

    Describes the use of solar cookers in the science classroom. Includes instructions for construction of a solar cooker, an explanation of how solar cookers work, and a number of suggested activities. (DS)

  12. Coupling the dynamics of boundary layers and evolutionary dunes.

    PubMed

    Ortiz, Pablo; Smolarkiewicz, Piotr K

    2009-04-01

    A theoretical formulation and corresponding numerical solutions are presented for fluid flow and sediment transport past evolutionary sand dunes. Time-dependent curvilinear coordinates are employed to fully couple flow aloft with the developing landform. The differential conservation law that defines shape of the lower boundary depends on details of local surface stress, thereby favoring the large eddy simulation of the boundary layer. To shrink the gap between the time scales characteristic of planetary boundary layer flows O(10(3)) s and sand dune evolution O(10(6)) s, a hypothetical "severe-wind scenario" is adopted with the saltation flux amplified up to 3 orders of magnitude. While the results are largely insensitive to the rescaling, the efficacy of computations is greatly improved. The flux-form partial differential equation for the interface profile--via saltation and sand avalanches--is formulated as an advection-diffusion equation, to facilitate discrete integrations. Numerical experiments verify the adopted theoretical framework by reproducing scaling results reported in the literature. The versatility of the approach is illustrated with evolution of a sandhole--an example of application likely never addressed in the literature, yet realizable in nature. PMID:19518224

  13. Multiscale bed form interactions and their implications for the abruptness and stability of the downwind dune field margin at White Sands, New Mexico, USA

    NASA Astrophysics Data System (ADS)

    Pelletier, Jon D.; Jerolmack, Douglas J.

    2014-11-01

    The downwind margin of White Sands dune field is an abrupt transition from mobile aeolian dunes to a dune-free vegetated surface. This margin is also relatively stable; over the past 60 years it has migrated several times more slowly than the slowest dunes within the dune field, resulting in a zone of dune coalescence, aggradation, and, along most of the margin, development of a dune complex (i.e., dunes superimposed on draas). Repeat terrestrial laser scanning surveys conducted over a 3 month period demonstrate that sediment fluxes within the dune complex decrease on approach to the margin. Computational fluid dynamics modeling indicates that this decrease is due, in part, to a decrease in mean turbulent bed shear stress on the lee side of the dune complex as a result of flow line divergence or sheltering of the lee-side dunes by the stoss side of the dune complex. Conservation of mass demands that this decrease in bed shear stress causes aggradation. We speculate that aggradation on the lee side of the dune complex further enhances the sheltering effect in a positive feedback, contributing to the growth and/or maintenance of the dune complex and a relatively abrupt and stable dune field margin. Our model and data add to a growing body of evidence that aeolian dune field patterns are influenced by feedbacks that occur at scales larger than individual dunes.

  14. Laboratory studies of dune sand for the use of construction industry in Sri Lanka

    NASA Astrophysics Data System (ADS)

    de Silva Jayawardena, Upali; Wijesuriya, Roshan; Abayaweera, Gayan; Viduranga, Tharaka

    2015-04-01

    With the increase of the annual sand demand for the construction industry the excessive excavation of river sand is becoming a serious environmental problem in Sri Lanka. Therefore, it is necessary to explore the possibility for an alternative to stop or at least to minimize river sand mining activities. Dune sand is one of the available alternative materials to be considered instead of river sand in the country. Large quantities of sand dunes occur mainly along the NW and SE coastal belt which belong to very low rainfall Dry Zone coasts. The height of dune deposits, vary from 1m to about 30 meters above sea level. The objective of this paper is to indicate some studies and facts on the dune sand deposits of Sri Lanka. Laboratory studies were carried out for visual observations and physical properties at the initial stage and then a number of tests were carried out according to ASTM standards to obtain the compressive strength of concrete cylinders and mortar cubes mixing dune sand and river sand in different percentages keeping a constant water cement ratio. Next the water cement ratio was changed for constant dune sand and river sand proportion. Microscopic analysis shows that the dune sand consist of 95 % of quartz and 5 % of garnet, feldspar, illmenite and other heavy minerals with clay, fine dust, fine shell fragments and organic matters. Grains are sub-rounded to angular and tabular shapes. The grain sizes vary from fine to medium size of sand with silt. The degree of sorting and particle size observed with dune sands are more suited with the requirement of fine aggregates in the construction industry. The test result indicates that dune sand could be effectively used in construction work without sieving and it is ideal for wall plastering due to its'-uniformity. It could also be effectively used in concrete and in mortars mixing with river sand. The best mixing ratio is 75% dune sand and 25% river sand as the fine aggregate of concrete. For mortar the mixing percentage is 50%. The best water cement ratio for mix proportion is 0.45. It was observed that the available amount of dune sand can be extracted to meet the demand for sand in construction industry. However, the extraction of dune sand from the areas close to the sea will cause several social, environmental and legal problems. Therefore sand mining from dunes must be commenced after making a detailed Environmental Impact Assessment.

  15. Investigation of the sand sea with the tallest dunes on Earth: China's Badain Jaran Sand Sea

    NASA Astrophysics Data System (ADS)

    Dong, Zhibao; Qian, Guangqiang; Lv, Ping; Hu, Guangyin

    2013-05-01

    China's Badain Jaran Sand Sea features the tallest dunes on Earth and a unique mega-dune-lake landscape. It had been explored little until the 1990s, though early scientific explorations surrounding the sand sea had begun by the early 20th century. Heated debates now focus on the desert environment, and particularly how the mega-dunes and desert lakes develop and evolve. This paper reviews the status of these debates and summarizes the supporting evidences. The environmental research mainly concerns formation and evolution of the sand sea, and its relationship with climate change. The proposed formation time ranges from the Early Pleistocene to the Holocene. Opinions vary about climate change on different time scales. The reconstructed climate change history is shorter than the sand sea's history, with the longest record extending to the Late Pleistocene. The mega-dune research focuses on sediments, dune morphology, and formation processes. It remains unclear whether the mega-dunes result primarily from wind action, control by the underlying topography, or groundwater maintenance. The sources of lake water are also debated, but there are four main hypotheses: atmospheric precipitation, groundwater from nearby areas, precipitation and snowmelt in remote areas such as the Qilian Mountains and the Qinghai-Tibetan Plateau, or paleowater that formed during past periods of wet climate. We believe that the sand sea deserves further study in terms of its dune geomorphology, evolution, and hydrology, and their responses to climate change. Meteorological and hydrological observations and monitoring in the sand sea are particularly necessary.

  16. Eolian deposition cycles since AD 500 in Playa San Bartolo lunette dune, Sonora, Mexico: Paleoclimatic implications

    NASA Astrophysics Data System (ADS)

    Ortega, Beatriz; Schaaf, Peter; Murray, Andrew; Caballero, Margarita; Lozano, Socorro; Ramirez, Angel

    2013-12-01

    Records of past climatic changes in desert environments are scarce due to the poor preservation of biological proxies. To overcome this lack we consider the paleoenvironmental significance and age of a lunette dune at the eastern rim of Playa San Bartolo (PSB) in the Sonoran Desert (Mexico). Thermoluminescence and optical stimulated luminescence (TL and OSL) provide the chronology of lunette dune development. Mineralogical, geochemical (major, trace and REE element concentrations) and rock magnetic analyses allow for the assessment of sediment provenance and changes in the composition of the PSB dune over time. The upper 6 m of dune accumulation occurred over the past 1.5 ka, largely during AD 500-1200, a period that correlates with the Medieval climatic anomaly (AD 300-1300). Variability in composition of dune sediments is attributed to changes in sediment sources. Sand sized deposits are mainly eroded from granitoids from nearby outcrops. Sandy silt deposits, rich in evaporative minerals, resulted after the flooding of PSB, later deflation and accumulation of both detritic and authigenic components in the dune. These findings suggest that main dune accretion occurred during regionally extended drought conditions, disrupted by sporadic heavy rainfall.

  17. Solar Geometry

    Atmospheric Science Data Center

    2014-09-25

    Solar Noon (GMT time) The time when the sun is due south in the ... and sunset.   Daylight average of hourly cosine solar zenith angles (dimensionless) The average cosine of the angle ... overhead during daylight hours.   Cosine solar zenith angle at mid-time between sunrise and solar noon ...

  18. Water resources of Sleeping Bear Dunes National Lakeshore, Michigan

    USGS Publications Warehouse

    Handy, A.H.; Stark, J.R.

    1984-01-01

    Sleeping Bear Dunes National Lakeshore in a water-rich area. It borders Lake Michigan and several small streams flow through the park to the lake. Small lakes are numerous within the park and near its boundaries. Ground water is available at most places in the park and wells yield as much as 100 gallons per minute. Water from streams, lakes, wells, and springs is of good quality. Dissolved solids range from 35 to 180 mg/L in lakes, from 145 to 214 mg/L in streams, and from 136 to 468 mg/L in groundwater. Analyses of samples for pesticides and trace metals indicate that no pesticides are present in the water, and that concentrations of trace metals do not exceed recommended drinking-water standards. Surface and ground water are available in sufficient quantity in most areas of the park for the development of water supplies for visitor 's centers, campgrounds, picnic areas, and other park facilities. (USGS)

  19. Geospatial analysis of a coastal sand dune field evolution: Jockey's Ridge, North Carolina

    NASA Astrophysics Data System (ADS)

    Mitasova, Helena; Overton, Margery; Harmon, Russell S.

    2005-12-01

    Preservation and effective management of highly dynamic coastal features located in areas under development pressures requires in-depth understanding of their evolution. Modern geospatial technologies such as lidar, real time kinematic GPS, and three-dimensional GIS provide tools for efficient acquisition of high resolution data, geospatial analysis, feature extraction, and quantification of change. These techniques were applied to the Jockey's Ridge, North Carolina, the largest active dune field on the east coast of the United States, with the goal to quantify its deflation and rapid horizontal migration. Digitized contours, photogrammetric, lidar and GPS point data were used to compute a multitemporal elevation model of the dune field capturing its evolution for the period of 1974- 2004. In addition, peak elevation data were available for 1915 and 1953. Analysis revealed possible rapid growth of the dune complex between 1915-1953, followed by a slower rate of deflation that continues today. The main dune peak grew from 20.1 m in 1915 to 41.8 m in 1953 and has since eroded to 21.9 m in 2004. Two of the smaller peaks within the dune complex have recently gained elevation, approaching the current height of the main dune. Steady annual rate of main peak elevation loss since 1953 suggests that increase in the number of visitors after the park was established in 1974 had little effect on the rate of dune deflation. Horizontal dune migration of 3-6 m/yr in southerly direction has carried the sand out of the park boundaries and threatened several houses. As a result, the south dune section was removed and the sand was placed at the northern end of the park to serve as a potential source. Sand fencing has been an effective management strategy for both slowing the dune migration and forcing growth in dune elevation. Understanding the causes of the current movements can point to potential solutions and suggest new perspectives on management of the dune as a tourist attraction and as a recreation site, while preserving its unique geomorphic character and dynamic behavior.

  20. Migration trachéale d'une canule de trachéotomie: complication exceptionnelle

    PubMed Central

    Chouikh, Chakib; El Moqaddem, Amine; Benmakhlouf, Anas; Naanaa, Saad; El Koraichi, Alae; El Kettani, Salma; Jahidi, Ali

    2014-01-01

    La trachéotomie est un geste chirurgical de survie largement pratiqué dans les services des urgences et de réanimation. En fonction de l'indication de sa réalisation, elle peut être transitoire ou définitive. Dans ce dernier cas le port d'une canule de trachéotomie de manière prolongée peut exposer à certaines complications qui peuvent s'avérer graves. Nous présentons un cas très rare d'un enfant présentant un syndrome de Guillain Barré, trachéotomisé depuis 4 ans suite à une sténose trachéale par intubation prolongée et portant une canule de trachéotomie métallique de type KRISHABER qui s'est présenté aux urgences dans un tableau de détresse respiratoire suite à la migration trachéale de sa canule. La trachéotomie est l'ouverture à la peau de la trachée cervicale, et à la mise d'une canule qui a pour but de permettre la respiration en court-circuitant les voies aériennes supérieures. De réalisation simple et codifiée le plus souvent, elle présente des risques de complications post opératoires notamment tardives. Les plus décrites sont les granulomes, les sténoses trachéales, les infections, et les fistules. La migration trachéale de la canule de trachéotomie reste exceptionnelle. Elle résulte d'un mauvais entretien qui fragilise la canule et doit être prise en charge en urgence. La trachéotomie définitive nécessite une surveillance régulière, un entretien et des soins de canules rigoureux pour éviter la survenue de complications qui peuvent être graves. Chez l'enfant, l'utilisation de canules souples en PVC ou en silicone doit être préférée aux canules métalliques. PMID:25368730

  1. Species sorting dominates plant metacommunity structure in coastal dunes

    NASA Astrophysics Data System (ADS)

    Brunbjerg, Ane Kirstine; Ejrnæs, Rasmus; Svenning, Jens-Christian

    2012-02-01

    It has long been thought that environmental factors determine plant community assembly, but it is now increasingly argued that geographic spatial processes such as dispersal may also matter. Notably, the metacommunity framework considers local communities to be linked by dispersal and different theories hereunder assign varying importance to dispersal limitation and local environmental species sorting. At present the relative importance of these factors across habitats, geographic regions, and spatial scales remains unclear. The present study assessed the relative importance of species sorting by the local environment and broader-scale geographic spatial processes for local plant species composition using a data set of 3924 plots from coastal dunes across a large region (Denmark). We used ordination to identify the main gradients in species composition, and Linear Mixed-Effects modelling (LME) to estimate the relative importance of local environment and multi-scale random geographic factors as determinants of floristic gradients. In addition, we assessed the dependence of species composition on local environment and geographic distance using Mantel tests. The LME analyses found local species sorting to be the dominant determinant in this metacommunity system, with soil moisture, pH, and fertility requirement patterns explaining ?77% of the compositional gradients, while geographic factors accounted for ?2%. Partial Mantel tests confirmed this finding, with 31.6% of the variation in species dissimilarity explained by environmental species sorting and just 1.6% by geographical distance. The apparently limited impact of dispersal limitation or other geographic spatial processes may reflect high habitat continuity and efficient dispersal by strong winds and ocean currents in the Danish coastal-dune metacommunity system.

  2. Influence of kinetic and electrostatic properties of interface states on the efficiency of a MIS tunnel solar cell

    E-print Network

    Paris-Sud XI, Université de

    write and resolve numerically the complete equations goveming the working of a MIS tunnel diode under of a MIS tunnel solar cell G. Pananakakis, G. Kamarinos and P. Viktorovitch « Physique des Composants à résolvons les équations de transport complètes décrivant le fonctionnement d'une cellule solaire MIS tunnel

  3. They're Alive! Present-Day Evolution of Martian Dunes

    NASA Technical Reports Server (NTRS)

    Diniega, S.; Bridges, N.; Hansen, C.

    2011-01-01

    The sharp brinks and margins, smooth and steep lee slopes, and lack of superimposed landforms (such as small impact craters) on many Martian sand dunes suggests that these features are geologically young clean brinks and smooth/steep lee slopes (HiRISE image PSP_010413_1920; 20 deg N,79 deg E; image widthis about 500m).Within the last decade, and often primarily through the detailed inspection of high-resolution (HiRISE) images, we have finally found clear evidence that many dunes of Mars are active -- through both aeolian and seasonal (frost) processes. However, it is yet unclear if active dune formation does occur or if we are observing surficial modification of dunes which formed under different climate conditions.

  4. Giant Linear Dunes as the Formation Pathway to Megabarchan Chains: Titan and the Rub 'Al Khali

    NASA Astrophysics Data System (ADS)

    Lorenz, R. D.; Radebaugh, J.

    2015-05-01

    We suggest megabarchans cannot grow from barchans. Rather sand accumulates as giant linear dunes in a bidirectional regime which has since become more unidirectional. We see this pattern on Titan and in the field in the .United Arab Emirates.

  5. Shrubs as ecosystem engineers in a coastal dune: influences on plant populations, communities and ecosystems

    E-print Network

    Cushman, J. Hall

    and nitrate. Rates of nitrate mineralization were higher under Lupinus, followed by Ericameria and then open dune. At landscape level, the two shrubs ­ and their distinctive vegetation and soils ­ frequently had

  6. A scaling law for aeolian dunes on Mars, Venus, Earth, and for subaqueous ripples

    E-print Network

    Claudin, Philippe

    A scaling law for aeolian dunes on Mars, Venus, Earth, and for subaqueous ripples Philippe Claudin tunnel reproducing conditions close to Venus' atmosphere and in the low pressure CO2 Martian atmosphere

  7. Conceptual Design and Physical Model Tests of a Levee-in-Dune Hurricane Barrier 

    E-print Network

    West, Nicholas Allan

    2014-12-04

    that simulate 100-year storm damage caused by both surge and waves. Dune and beach morphology for each concept is measured through laser profiling techniques, and each concept is evaluated based on calculated erosion and accretion, as well as design...

  8. An aeolian transport model for the selection of dune restoration alternatives 

    E-print Network

    Bell, James Clayton

    2007-04-25

    the course of the study it became apparent that no model or software existed capable of demonstrating the effectiveness of available dune restoration alternatives. Building Beach�©, a coastal aeolian sand transport simulator, was developed in response...

  9. Parthnocarpie naturelle chez la tomate. II. -Etude d'une collection varitale

    E-print Network

    Paris-Sud XI, Université de

    traitements ont été appliqués : d'une part castration des fleurs, non suivie de pollinisation ; d'autre part pollinisation, soit manuelle après castration, soit naturelle sans castration. On a effectué l'étude comparée

  10. Population enumeration and the effects of oil and gas development on dune-dwelling lizards 

    E-print Network

    Smolensky, Nicole Limunga

    2009-05-15

    and gas development. The dune-dwelling lizard community contains a habitat specialist, Sceloporus arenicolus, that is of particular interest because it has a very limited geographic distribution that is entirely subject to oil and gas development. Distance...

  11. The Impact of Devegetated Dune Fields on North American Climate During the Late Medieval Climate Anomaly

    NASA Technical Reports Server (NTRS)

    Cook, B. I.; Seager, R.; Miller, R. L.

    2011-01-01

    During the Medieval Climate Anomaly, North America experienced severe droughts and widespread mobilization of dune fields that persisted for decades. We use an atmosphere general circulation model, forced by a tropical Pacific sea surface temperature reconstruction and changes in the land surface consistent with estimates of dune mobilization (conceptualized as partial devegetation), to investigate whether the devegetation could have exacerbated the medieval droughts. Presence of devegetated dunes in the model significantly increases surface temperatures, but has little impact on precipitation or drought severity, as defined by either the Palmer Drought Severity Index or the ratio of precipitation to potential evapotranspiration. Results are similar to recent studies of the 1930s Dust Bowl drought, suggesting bare soil associated with the dunes, in and of itself, is not sufficient to amplify droughts over North America.

  12. Quantifying landscape-ecological succession in a coastal dune system using sequential aerial photography and GIS

    Microsoft Academic Search

    2002-01-01

    Summary  This contribution presents an attempt to measure the path of habitat and vegetation succession in a coastal dune system (Kenfig\\u000a Burrows, South Wales) using remote sensing and GIS. The loss of slack habitats associated with the continuing stabilization\\u000a of this dune system is a major cause for concern. These habitats support a range of plant species, including the rare fen

  13. Spatial Distribution of Soil Nematode Communities in Stable and Active Sand Dunes of Horqin Sandy Land

    Microsoft Academic Search

    Xiaoke Zhang; Xiwen Dong; Wenju Liang

    2010-01-01

    To explore the ecological significance of artificial plantation and the restoration process in sand dune ecosystems, the spatial distribution of soil nematode communities in stable and active sand dunes were investigated in northeastern Inner Mongolia, China. Soil nematode community structure and composition at five soil depths (0–5 cm, 5–10 cm, 10–20 cm, 20–40 cm, and 40–60 cm) and three slope positions (windward slope, top slope,

  14. Optically stimulated luminescence dating of aeolian sand in the otindag dune field and holocene climate change

    USGS Publications Warehouse

    Zhou, Y.L.; Lu, H.Y.; Mason, J.; Miao, X.D.; Swinehart, J.; Goble, R.

    2008-01-01

    The dune system in Otindag sand field of northern China is sensitive to climate change, where effective moisture and related vegetation cover play a controlling role for dune activity and stability. Therefore, aeolian deposits may be an archive of past environmental changes, possibly at the millennial scale, but previous studies on this topic have rarely been reported. In this study, thirty-five optically stimulated luminescence (OSL) ages of ten representative sand-paleosol profiles in Otindag sand field are obtained, and these ages provide a relatively complete and well-dated chronology for wet and dry variations in Holocene. The results indicate that widespread dune mobilization occurred from 9.9 to 8.2 ka, suggesting a dry early Holocene climate. The dunes were mainly stabilized between 8.0 and 2.7 ka, implying a relatively wet climate, although there were short-term penetrations of dune activity during this wet period. After ???2.3 ka, the region became dry again, as inferred from widespread dune activity. The "8.2 ka" cold event and the Little Ice Age climatic deterioration are detected on the basis of the dune records and OSL ages. During the Medieval Warm Period and the Sui-Tang Warm Period (570-770 AD), climate in Otindag sand field was relatively humid and the vegetation was denser, and the sand dunes were stabilized again. These aeolian records may indicate climate changes at millennial time scale during Holocene, and these climatic changes may be the teleconnection to the climate changes elsewhere in the world. ?? Science in China Press and Springer-Verlag GmbH 2008.

  15. The buried dune-fields of the Río Paraná, Argentina: an extreme in sedimentary preservation?

    NASA Astrophysics Data System (ADS)

    Reesink, Arjan; Van den Berg, Janrik; Parsons, Daniel; Amsler, Mario; Best, Jim; Hardy, Richard; Szuipany, Ricardo

    2015-04-01

    Extremes in dune preservation can be used to constrain and extend our understanding of sedimentary preservation. Ground Penetrating Radar surveys reveal that fully-preserved dune fields exist in bar deposits in the Río Paraná, Argentina. These observations contradict the notion that the tops of dunes are always eroded by recurrence of scour, and provide a unique opportunity to investigate the completeness of the fluvial deposits. These intact dune fields i) are found in >5% of the mid-channel bar deposits ii) exist only in the upper 5 m of the channel deposits, iii) are restricted to unit-bar troughs, iv) are up to 300 m in length, v) occur in multiple levels, vi) show signs of reactivation, and vii) match the size of average-flow dunes rather than those that form in extreme floods. These observations suggest that the development, abandonment, and burial of dune-fields is a common process that is linked to the distinct changes in flow and sediment transport that occur in the lee of bars in response to changes in discharge, especially in large seasonal rivers. Further analysis shows that changes in flow conditions caused by bar-scale morphology affect dune heights, lengths, bedform shapes and scour, the flux of sediment to the bed, and bedform migration rates: all the basic parameters known to control dune preservation. Thus, bar-scale variation in flow and sediment transport can be expected to cause differences in preservation potential between the thalweg, and the flanks, tops, lee- and stoss slopes of larger bar forms. This highlights that the physical boundary conditions that control sedimentary preservation do not necessarily coincide with an easily classified environment such as a river channel, and provides a conceptual basis for improvements in the interpretation, discrimination, and characterisation of river channel deposits.

  16. Ecological effects of reactivation of artificially stabilized blowouts in coastal dunes

    Microsoft Academic Search

    J. H. van Boxel; P. D. Jungerius; N. Kieffer; N. Hampele

    1997-01-01

    In an inner dune area in the Dutch coastal dunes several artificially stabilized blowouts were reactivated. The purpose was\\u000a to investigate whether these reactivated blowouts could remain active despite the increased atmospheric deposition of nutrients,\\u000a how much area would be affected by sand from the blowouts, whether the vegetation would respond to the deposition of sand,\\u000a and whether the reactivation

  17. Low atmospheric nitrogen loads lead to grass encroachment in coastal dunes, but only on acid soils

    Microsoft Academic Search

    Eva S. Remke; Emiel Brouwer; Annemieke M Kooijman; Irmgard Blindow; Jan G. M. Roelofs

    2009-01-01

    The impact of atmospheric N-deposition on succession from open sand to dry, lichen-rich, short grassland, and tall grass vegetation dominated by Carex arenaria was surveyed in 19 coastal dune sites along the Baltic Sea. Coastal dunes with acid or slightly calcareous sand reacted differently to atmospheric wet deposition of 5–8 kg N ha?1 y?1. Accelerated acidification, as well as increased growth of Carex and

  18. The Fragility and Conservation of the World's Coastal Dunes: Geomorphological, Ecological and Socioeconomic Perspectives

    Microsoft Academic Search

    M. L. Martínez; M. A. Maun; N. P. Psuty

    Coastal dunes have a worldwide distribution and are comprised of a variety of forms going through successional changes in\\u000a geomorphology and ecological association. Some changes are driven by natural processes whereas other changes are products\\u000a of human endeavors. Coastal dunes are highly valuable multifunctional ecosystems that occupy a unique natural niche.Further,\\u000a these same systems are ideal locations for recreation, replenishment

  19. Atlantic storminess and historical sand drift in Western Europe: implications for future management of coastal dunes

    Microsoft Academic Search

    Michèle L. Clarke; Helen M. Rendell

    2011-01-01

    Historical records of sand drift and dune-building along the coastline of Western Europe provide insights into the natural\\u000a processes of sand dune accretion and both the impacts of, and human responses to, sand incursions. The analysis of documentary\\u000a records, instrumental data and proxy records over the last 1,000 years indicates that this period, which included the Little\\u000a Ice Age (AD 1570–1900),

  20. An evaluation of the vegetation developed after artificially stabilizing South African coastal dunes with indigenous species

    Microsoft Academic Search

    A. M. Avis

    1995-01-01

    A total of 17 sites along the eastern Cape coastline, which had been established with indigenous species, were sampled to\\u000a assess species composition and abundance. The areas sampled ranged from small blowout dunes of 1 ha, to extensive transverse\\u000a dune fields of 134 ha; age at the time of sampling ranged from 2 to 20 yr. The total mean percentage

  1. Even low to medium nitrogen deposition impacts vegetation of dry, coastal dunes around the Baltic Sea

    Microsoft Academic Search

    Eva Remke; Emiel Brouwer; Annemieke Kooijman; Irmgard Blindow; Hans Esselink; Jan G. M. Roelofs

    2009-01-01

    Coastal dunes around the Baltic Sea have received small amounts of atmospheric nitrogen and are rather pristine ecosystems in this respect. In 19 investigated dune sites the atmospheric wet nitrogen deposition is 3-8 kg N ha(-1) yr(-1). The nitrogen content of Cladonia portentosa appeared to be a suitable biomonitor of these low to medium deposition levels. Comparison with EMEP-deposition data

  2. Mean flow, turbulence structure, and bed form superimposition across the ripple-dune transition

    Microsoft Academic Search

    Rocío Fernandez; Jim Best; Fabián López

    2006-01-01

    This paper describes a laboratory study of the dynamics of flow associated with three different stages of bed form amalgamation across the ripple-dune transition. Measurements of flow velocity were obtained over simplified fixed bed forms, designed to simulate conditions at the ripple:dune transition, using a 2D laser Doppler anemometer. This yielded information detailing the mean velocity field, turbulence statistics, local

  3. The growth responses of coastal dune species are determined by nutrient limitation and sand burial.

    PubMed

    Gilbert, Matthew; Pammenter, Norman; Ripley, Brad

    2008-05-01

    Past work suggests that burial and low nutrient availability limit the growth and zonal distribution of coastal dune plants. Given the importance of these two factors, there is a surprising lack of field investigations of the interactions between burial and nutrient availability. This study aims to address this issue by measuring the growth responses of four coastal dune plant species to these two factors and their interaction. Species that naturally experience either high or low rates of burial were selected and a factorial burial by nutrient addition experiment was conducted. Growth characteristics were measured in order to determine which characteristics allow a species to respond to burial. Species that naturally experience high rates of burial (Arctotheca populifolia and Scaevola plumieri) displayed increased growth when buried, and this response was nutrient-limited. Stable-dune species had either small (Myrica cordifolia, N-fixer) or negligible responses to burial (Metalasia muricata), and were not nutrient-limited. This interspecific difference in response to burial and/or fertiliser is consistent with the idea that burial maintains the observed zonation of species on coastal dunes. Species that are unable to respond to burial are prevented from occupying the mobile dunes. Species able to cope with high rates of burial had high nitrogen-use efficiencies and low dry mass costs of production, explaining their ability to respond to burial under nutrient limitation. The interaction between burial and nutrient limitation is understudied but vital to understanding the zonation of coastal dune plant species. PMID:18246372

  4. Alluvial Fans on Dunes in Kaiser Crater Suggest Niveo-Aeolian and Denivation Processes on Mars

    NASA Technical Reports Server (NTRS)

    Bourke, M. C.

    2005-01-01

    On Earth, cold region sand dunes often contain inter-bedded sand, snow, and ice. These mixed deposits of wind-driven snow, sand, silt, vegetal debris, or other detritus have been termed Niveo-aeolian deposits. These deposits are often coupled with features that are due to melting or sublimation of snow, called denivation features. Snow and ice may be incorporated into dunes on Mars in three ways. Diffusion of water vapour into pore spaces is the widely accepted mechanism for the accretion of premafrost ice. Additional mechanisms may include the burial by sand of snow that has fallen on the dune surface or the synchronous transportation and deposition of snow, sand and ice. Both of these mechanisms have been reported for polar dunes on Earth. Niveo-aeolian deposits in polar deserts on Earth have unique morphologies and sedimentary structures that are generally not found in warm desert dunes. Recent analysis of MOC-scale data have found evidence for potential niveo-aeolian and denivation deposits in sand dunes on Mars.

  5. Morphologic and Dynamic Similarities Between Polygonal Dunes on Mars and Interference Ripples on Earth

    NASA Astrophysics Data System (ADS)

    Rubin, D. M.; Newman, C. E.

    2012-12-01

    Some dunes in craters on Mars are similar in morphology to ripples formed in complicated multidirectional flows on Earth. Similarities in morphology of these ripples on Earth and dunes on Mars include (1) relatively symmetrical cross-sections, and (2) crests with planform polygonal patterns, "tile" patterns, or "ladderback" structure. On Earth, bedforms with these morphologies are produced by complicated directionally-varying flows such as those generated by interfering waves (Figure 1), recirculating flows in the lee of large dunes, and recirculating flows in lateral separation eddies in rivers. Here we hypothesize that dunes with these morphologies on Mars (Figure 2) are also formed by multidirectional flows. Processes that might produce multidirectional winds on Mars include: heating and cooling that cause daily changes in wind direction; winds that vary in direction seasonally or with the passage of storms; and recirculating flows within steep-walled craters or within the troughs of larger dunes. This work was funded by NASA Mars Data Analysis Program.igure 1. Polygonal ripples formed by waves in shallow water; boot print is 30 cm long. igure 2. Polygonal dunes in Victoria Crater, Mars; crater is approximately 700 m in diameter and 70 m deep; image from NASA/JPL-Caltech/University of Arizona.

  6. Mesophilic Actinomycetes in the natural and reconstructed sand dune vegetation zones of Fraser Island, Australia.

    PubMed

    Kurtböke, D I; Neller, R J; Bellgard, S E

    2007-08-01

    The natural coastal habitat of Fraser Island located in the State of Queensland, Australia, has been disturbed in the past for mining of the mineral sand ilmenite. Currently, there is no information available on whether these past mining disturbances have affected the distribution, diversity, and survival of beneficial soil microorganisms in the sand dunes of the island. This in turn could deleteriously affect the success of the natural regeneration, plant growth, and establishment on the sand dunes. To support ongoing restoration efforts at sites like these mesophilic actinomycetes were isolated using conventional techniques, with particular emphasis on the taxa previously reported to produce plant-growth-promoting substances and providing support to mycorrhizal fungi, were studied at disturbed sites and compared with natural sites. In the natural sites, foredunes contained higher densities of micromonosporae replaced by increasing numbers of streptomycete species in the successional dune and finally leading to complex actinomycete communities in the mature hind dunes. Whereas in the disturbed zones affected by previous mining activities, which are currently being rehabilitated, no culturable actinomycete communities were detected. These findings suggest that the paucity of beneficial microflora in the rehabilitated sand dunes may be limiting the successful colonization by pioneer plant species. Failure to establish a cover of plant species would result in the mature hind dune plants being exposed to harsh salt and climatic conditions. This could exacerbate the incidence of wind erosion, resulting in the destabilization of well-defined and vegetated successional dunal zones. PMID:17578635

  7. Overland flow in sand dunes: feedbacks between aeolian and hydrological processes

    NASA Astrophysics Data System (ADS)

    Fagherazzi, S.; Priestas, A. M.

    2012-12-01

    During the summer of 2005, Hurricane Dennis overwashed the eastern portion of St. George Island, part of the northwest barrier island chain located along the Florida Panhandle. In this paper, LiDAR-based morphological changes of the barrier island are analyzed, along with the short-term post-storm recovery of secondary dunes. Vegetation deterred dune migration, thus favoring dune growth and reducing erosion due to wind. In contrast, the absence of vegetation inhibited dune growth. Low-elevation areas within the dunes were subject to flooding via saturation overland flow following moderate storm surges and rainfall events. Using a high resolution topographic survey and simple hydrology models, we estimate the discharge and velocities from storm surge return flow and saturation overland flow. Results show that return flow velocities are of the same magnitude as the critical velocity necessary to mobilize sand when a hydraulic connection between the watershed and back-barrier bay is present. Storms of moderate strength and rainfall intensity may be sufficient to keep the return channels open within the back-barrier, thus providing natural conduits for water exchange from overwash events during extreme storm surges triggered by hurricanes. We conclude that hydrological and aeolian processes are strictly coupled in dune fields characteristic of many barrier islands along the US coast.

  8. Solar Cooking

    Atmospheric Science Data Center

    2014-09-25

    ... (kWh/m2/day) Amount of electromagnetic energy (solar radiation) incident on the surface of the earth. Also referred to as total or global solar radiation.   Midday insolation (kWh/m2/day) Average ...

  9. A 45-year time series of Saharan dune mobility from remote sensing

    NASA Astrophysics Data System (ADS)

    Vermeesch, P.

    2012-04-01

    Decadal trends in the aeolian dust record of the Sahara affect the global climate system and the nutrient budget of the Atlantic Ocean. One proposed cause of these trends are changes in the frequency and intensity of dust storms, which have hitherto been hard to quantify. Because sand flux scales with the cube of wind speed, dune migration rates can be used as a proxy for storminess. Relative changes in the storminess of the Sahara can thus be monitored by tracking the migration rates of individual sand dunes over time. The Bodélé Depression of northern Chad was selected as a target area for this method, because it is the most important point-source of aeolian dust on the planet and features the largest and fastest dunes on Earth. A collection of co-registered Landsat, SPOT, and ASTER scenes, combined with declassified American spy satellite images was used to construct a 45 year record of dune migration in the Bodélé Depression. One unexpected outcome of the study was the observation of binary dune interactions in the imagery sequence, which reveals that when two barchan dunes collide, a transfer of mass occurs so that one dune appears to travel through the other unscathed, like a solitary wave. This confirms a controversial numerical model prediction and settles a decade-old debate in aeolian geomorphology. The COSI-Corr change detection method was used to measure the dune migration rates from 1984 until 1987, 1990, 1996, 2000, 2003, 2005, 2007, 2008, 2009, and 2010. An algorithm was developed to automatically warp the resulting displacement fields back to a common point in time. Thus, individual image pixels of a dune field were tracked over time, allowing the extraction of a time series from the co-registered satellite images without further human intervention. The automated analysis was extended further back into the past by comparison of the 1984 image with declassified American spy satellite (Corona) images from 1965 and 1970. Due to the presence of specks of dust as well as image distortions caused by shrinking of the photographic film, it was not possible to automatically measure the dune displacements of these scenes with COSI-Corr. Instead, the image was georeferenced and coregistered to the 1984 Landsat imagery by third order polynomial fits to 531 tie points, and the displacements of ten large barchan dunes were measured by hand. Thanks to the 19-year time lapse between the two images used for these 'analog' measurements, their precision is better than 5%, which is comparable with that of the automated COSI-Corr analysis. The resulting dune celerities are identical to the automated measurements, which themselves show little or no temporal variability over the subsequent 26 years. The lack of any trend in the time series of dune celerity paints a picture of remarkably stable dune mobility over the past 45 years. None of the distributions fall outside the overall average of 25m/yr. The constant dune migration rates resulting from our study indicate that there has been no change in the storminess of the Sahara over the past 45 years. The observed dust trends are therefore caused by changes in vegetation cover, which in turn reflect changes in precipitation and land usage. This work highlights the importance of the hyper-arid Bodélé Depression, which provides a steady but finite supply of aeolian dust to the atmosphere without which nutrient fluxes and terrestrial albedo would be more variable than they are today.

  10. Solar Distillation

    Microsoft Academic Search

    Rahul Dev; Gopal Nath Tiwari

    \\u000a “Solar distillation” is a technology for producing potable water from brackish and underground water of low-quality at low\\u000a cost. It can reduce water-scarcity problems together with other water purification technologies. Solar distillation is analogous\\u000a to natural hydrological cycle. It uses an apparatus called a solar still in which water is evaporated using solar energy,\\u000a a form of renewable energy, and

  11. Solar apparatus

    Microsoft Academic Search

    1987-01-01

    A solar steam generating apparatus for generating process steam in the temperature range of 100°C to 200°C is described comprising: (a) a solar collector comprised of tubular collectors (b) heat storage means, and first duct means communicating with the solar collector and with the heat storage means to permit the transfer of heat from the air heated by the solar

  12. Solar Equipment

    NASA Technical Reports Server (NTRS)

    1983-01-01

    A medical refrigeration and a water pump both powered by solar cells that convert sunlight directly into electricity are among the line of solar powered equipment manufactured by IUS (Independent Utility Systems) for use in areas where conventional power is not available. IUS benefited from NASA technology incorporated in the solar panel design and from assistance provided by Kerr Industrial Applications Center.

  13. Solar technology

    Microsoft Academic Search

    Finneran

    1983-01-01

    This article predicts that the future pace of solar progress will continue to depend as much on political and economic factors as on the ingenuity of scientists and engineers worldwide. Points out that solar technology is not yet cheap enough to attract widespread investment. Reports that the Reagan administration has cut research funds for solar energy from $633 million in

  14. Solar System

    NSDL National Science Digital Library

    Ms. Wright

    2009-10-09

    An introduction to to the solar system. How to distinguish between the different planets. Activities to play while getting to know the solar system. Cosmic Cookies Solar System Scavenger Hunt Edible Earth Strawkets and Control Strawkets and Thrust Strawkets and Weight ...

  15. Solar windows

    Microsoft Academic Search

    Shailly Jain; Rohan Jhaveri

    2011-01-01

    Till date, to harness energy from the sun we have used solar panels. These solar panels have to be installed on the roof-tops. Imagine windows that not only provide a clear view and illuminate rooms, but also use sunlight to efficiently help power the building they are part of. Solar panels used in today track the sun to generate high

  16. Remotely sensed dune sand flux measurements in the dustiest place on Earth (Bodélé, Chad)

    NASA Astrophysics Data System (ADS)

    Vermeesch, P.

    2009-12-01

    The Bodélé Depression of northern Chad is the dustiest place on Earth, thanks to a unique combination of two factors. First, the Bodélé is located downwind of a narrow gap between the Tibesti and Ennedi mountain ranges, which act as a funnel creating the strong winds of the Bodélé Low Level Jet. Second, the depression forms the deepest part of palaeo-lake Megachad, which once rivaled the Caspian Sea in size. When the lake dried out during the Holocene, it left behind thick deposits of diatomite, which currently provide an abundant and readily available source of dust. Previous work has shown that dust is primarily produced by eddies near the horns of barchan dunes. Using a new remote sensing technique called COSI-Corr, these barchans were shown to be not only the largest, but also the fastest on Earth, featuring the highest sand fluxes. Quantifying sand flux with field measurements is an expensive and time-consuming process. COSI-Corr -which stands for 'Co-registration of Optically Sensed Images and Correlation' and was originally developed for the purpose of detecting surface deformation caused by earthquakes- offers an alternative approach to measuring sand flux, using remote sensing. From pairs of ASTER imagery, dune migration in the Bodélé depression was successfully measured over time intervals of one month to 6.5 years. The displacement maps produced by COSI-Corr can be used to automatically distinguish dunes from interdunes, which is a crucial step towards calculating sand flux. Dune heights and volumes were obtained by interpolating a surface between the interdune areas and subtracting it from a digital elevation model. Multiplying height with celerity yields a pixel-by-pixel estimate of the sand flux. Applying this method to large diatomite dunes in the Bodélé confirms that these are some of the world’s fastest moving barchans. Plotting dune height against inverse celerity reveals sand flux at the dune crest of >200 m3/m/yr. Average dune sand flux values for the eastern and western Bodélé are 76 and 99 m3/m/yr, respectively. The contribution of the dunes to the total area-averaged sand flux is 24-29 m3/m/yr, which is ~10% of the saltation flux determined by previously published field measurements. The displacement field of quartz dunes in the northeastern Bodélé displayed as a vector field.

  17. Analysis of wind-blown sand movement over transverse dunes.

    PubMed

    Jiang, Hong; Huang, Ning; Zhu, Yuanjian

    2014-01-01

    Wind-blown sand movement often occurs in a very complicated desert environment where sand dunes and ripples are the basic forms. However, most current studies on the theoretic and numerical models of wind-blown sand movement only consider ideal conditions such as steady wind velocity, flat sand surface, etc. In fact, the windward slope gradient plays a great role in the lift-off and sand particle saltation. In this paper, we propose a numerical model for the coupling effect between wind flow and saltating sand particles to simulate wind-blown sand movement over the slope surface and use the SIMPLE algorithm to calculate wind flow and simulate sands transport by tracking sand particle trajectories. We furthermore compare the result of numerical simulation with wind tunnel experiments. These results prove that sand particles have obvious effect on wind flow, especially that over the leeward slope. This study is a preliminary study on windblown sand movement in a complex terrain, and is of significance in the control of dust storms and land desertification. PMID:25434372

  18. Australian Red Dune Sand: A Potential Martian Regolith Analog

    NASA Technical Reports Server (NTRS)

    Kuhlman, K. R.; Marshall, J.; Evans, N. D.; Luttge, A.

    2001-01-01

    To demonstrate the potential scientific and technical merits of in situ microscopy on Mars, we analyzed a possible Martian regolith analog - an acolian red dune sand from the central Australian desert (near Mt. Olga). This sand was chosen for its ubiquitous red coating and the desert environment in which is it found. Grains of this sand were analyzed using a variety of microanalytical techniques. A database of detailed studies of such terrestrial analogs would assist the study of geological and astrobiological specimens in future missions to Mars. Potential instrument concepts for in situ deployment on Mars include local electrode atom probe nanoanalysis (LEAP), vertical scanning white light interferometry (VSWLI), scanning electron microscopies, energy dispersive x-ray microanalysis (EDX), atomic force microscopy (AFM) and X-ray diffraction (XRD). While in situ deployment of these techniques is many years away, ground-based studies using these analytical techniques extend our understanding of the data obtained from instruments to be flown in the near future.

  19. Eye development in the Cape dune mole rat.

    PubMed

    Nikitina, Natalya V; Kidson, Susan H

    2014-03-01

    Studies on mammalian species with naturally reduced eyes can provide valuable insights into the evolutionary developmental mechanisms underlying the reduction of the eye structures. Because few naturally microphthalmic animals have been studied and eye reduction must have evolved independently in many of the modern groups, novel evolutionary developmental models for eye research have to be sought. Here, we present a first report on embryonic eye development in the Cape dune mole rat, Bathyergus suillus. The eyes of these animals contain all the internal structures characteristic of the normal eye but exhibit abnormalities in the anterior chamber structures. The lens is small but develops normally and exhibits a normal expression of ?- and ?-crystallins. One of the interesting features of these animals is an extremely enlarged and highly pigmented ciliary body. In order to understand the molecular basis of this unusual feature, the expression pattern of an early marker of the ciliary zone, Ptmb4, was investigated in this animal. Surprisingly, in situ hybridization results revealed that Ptmb4 expression was absent from the ciliary body zone of the developing Bathyergus eye. PMID:24570380

  20. Analysis of Wind-blown Sand Movement over Transverse Dunes

    PubMed Central

    Jiang, Hong; Huang, Ning; Zhu, Yuanjian

    2014-01-01

    Wind-blown sand movement often occurs in a very complicated desert environment where sand dunes and ripples are the basic forms. However, most current studies on the theoretic and numerical models of wind-blown sand movement only consider ideal conditions such as steady wind velocity, flat sand surface, etc. In fact, the windward slope gradient plays a great role in the lift-off and sand particle saltation. In this paper, we propose a numerical model for the coupling effect between wind flow and saltating sand particles to simulate wind-blown sand movement over the slope surface and use the SIMPLE algorithm to calculate wind flow and simulate sands transport by tracking sand particle trajectories. We furthermore compare the result of numerical simulation with wind tunnel experiments. These results prove that sand particles have obvious effect on wind flow, especially that over the leeward slope. This study is a preliminary study on windblown sand movement in a complex terrain, and is of significance in the control of dust storms and land desertification. PMID:25434372

  1. Population dynamics of some major woody species in relation to long-term succession on the dunes of Voorne

    Microsoft Academic Search

    Eddy van der Maarel; Nick de Cock; Ernie de Wildt

    1985-01-01

    This study is a follow-up of medium-term succession studies based on a vegetation map, scale 1:2 500, of the dunes near Oostvoorne made in 1959 and 1980. The area has a marked zonation with partly very young dunes and inner dunes at a distance of >1 200 m from the beach which are 800 yr old. The overall succession trend

  2. The scale of genetic differentiation in the Dunes Sagebrush-Lizard ( Sceloporus arenicolus ), an endemic habitat specialist

    Microsoft Academic Search

    Lauren M. Chan; Lee A. Fitzgerald; Kelly R. Zamudio

    2009-01-01

    The Dunes Sagebrush-Lizard (Sceloporus arenicolus) is a North American species endemic to sand-shinnery oak habitats of the Mescalero and Monahans sand dunes in eastern New\\u000a Mexico and western Texas. This lizard is listed as Endangered in New Mexico and exhibits habitat specificity at several geographic\\u000a scales. Dunes Sagebrush-Lizards are only found in topographically complex shinnery oak (Quercus havardii) dominated landscapes

  3. Solar flair.

    PubMed Central

    Manuel, John S

    2003-01-01

    Design innovations and government-sponsored financial incentives are making solar energy increasingly attractive to homeowners and institutional customers such as school districts. In particular, the passive solar design concept of daylighting is gaining favor among educators due to evidence of improved performance by students working in daylit classrooms. Electricity-generating photovoltaic systems are also becoming more popular, especially in states such as California that have high electric rates and frequent power shortages. To help spread the word about solar power, the U.S. Department of Energy staged its first-ever Solar Decathlon in October 2002. This event featured solar-savvy homes designed by 14 college teams. PMID:12573926

  4. Solar Energy: Solar System Economics.

    ERIC Educational Resources Information Center

    Knapp, Henry H., III

    This module on solar system economics is one of six in a series intended for use as supplements to currently available materials on solar energy and energy conservation. Together with the recommended texts and references (sources are identified), these modules provide an effective introduction to energy conservation and solar energy technologies.…

  5. Solar harness

    SciTech Connect

    Barker, O.P.

    1991-04-23

    This patent describes a solar harness system. I comprises a parabolic reflector having a specific theoretical focal point and having a series of focal points for the different colored light rays contained in solar lights; means for supporting the parabolic reflector; a solar harness apparatus, including: solar cells, each having an active surface, with the active surface of each solar cell being substantially parallel to one another and facing the same direction, and with the solar cells being stacked in line behind one another; magnets, with at least one magnet being located between each adjacent solar cell in the cells, each of the magnets being of adequate magnetic power to hold the solar cells in stacked arrangement therewith, without any other support and so as to create solderless contacts with each solar cell in series; means connected to one end of the stacked arrangement of solar cells and magnets for drawing electric current therefrom; means for supporting the harness apparatus at the focal point of a color of the colored light rays in solar light other than the red color focal point.

  6. Solar Sailing

    NASA Technical Reports Server (NTRS)

    Johnson, Les

    2009-01-01

    Solar sailing is a topic of growing technical and popular interest. Solar sail propulsion will make space exploration more affordable and offer access to destinations within (and beyond) the solar system that are currently beyond our technical reach. The lecture will describe solar sails, how they work, and what they will be used for in the exploration of space. It will include a discussion of current plans for solar sails and how advanced technology, such as nanotechnology, might enhance their performance. Much has been accomplished recently to make solar sail technology very close to becoming an engineering reality and it will soon be used by the world s space agencies in the exploration of the solar system and beyond. The first part of the lecture will summarize state-of-the-art space propulsion systems and technologies. Though these other technologies are the key to any deep space exploration by humans, robots, or both, solar-sail propulsion will make space exploration more affordable and offer access to distant and difficult destinations. The second part of the lecture will describe the fundamentals of space solar sail propulsion and will describe the near-, mid- and far-term missions that might use solar sails as a propulsion system. The third part of the lecture will describe solar sail technology and the construction of current and future sailcraft, including the work of both government and private space organizations.

  7. Analyses of a Large Climbing Dune in the Ka'u Desert, Hawaii and Implications for Understanding Dark Dunes on Mars

    NASA Astrophysics Data System (ADS)

    Craddock, R. A.; Tirsch, D.; Nanson, G.; Tooth, S.; Langhans, M.

    2011-03-01

    Our objectives are to (1) determine the history of basaltic dunes located in the Ka’u Desert of Hawaii, (2) ascertain changes in the characteristics of basaltic sediments as they are transported, and (3) acquire the VNIR spectra of these materials.

  8. Construction d'une matrice emplois -expositions pour le suivi pidmiologique des travailleurs de l'industrie nuclaire en France. Rsultats d'une tude-pilote.

    E-print Network

    Boyer, Edmond

    matrix for the epidemiological follow-up of workers in the French nuclear industry. Results of a pilot exposure among nuclear workers. Key words: Job exposure matrix. Nuclear industry. Uranium. Chemicals1 Construction d'une matrice emplois - expositions pour le suivi épidémiologique des travailleurs

  9. Mars Global Digital Dune Database (MGD3): North polar region (MC-1) distribution, applications, and volume estimates

    USGS Publications Warehouse

    Hayward, R.K.

    2011-01-01

    The Mars Global Digital Dune Database (MGD3) now extends from 90??N to 65??S. The recently released north polar portion (MC-1) of MGD3 adds ~844 000km2 of moderate- to large-size dark dunes to the previously released equatorial portion (MC-2 to MC-29) of the database. The database, available in GIS- and tabular-format in USGS Open-File Reports, makes it possible to examine global dune distribution patterns and to compare dunes with other global data sets (e.g. atmospheric models). MGD3 can also be used by researchers to identify areas suitable for more focused studies. The utility of MGD3 is demonstrated through three example applications. First, the uneven geographic distribution of the dunes is discussed and described. Second, dune-derived wind direction and its role as ground truth for atmospheric models is reviewed. Comparisons between dune-derived winds and global and mesoscale atmospheric models suggest that local topography may have an important influence on dune-forming winds. Third, the methods used here to estimate north polar dune volume are presented and these methods and estimates (1130km3 to 3250km3) are compared with those of previous researchers (1158km3 to 15 000km3). In the near future, MGD3 will be extended to include the south polar region. ?? 2011 by John Wiley and Sons, Ltd.

  10. High-Resolution Monitoring of Coastal Dune Erosion and Growth Using an Unmanned Aerial Vehicle

    NASA Astrophysics Data System (ADS)

    Ruessink, G.; Markies, H.; Van Maarseveen, M.

    2014-12-01

    Coastal foredunes lose and gain sand through marine and aeolian processes, but coastal-evolution models that can accurately predict both wave-driven dune erosion and wind-blown dune growth are non-existing. This is, together with a limited understanding of coastal aeolian process dynamics, due to the lack of adequate field data sets from which erosion and supply volumes can be studied simultaneously. Here, we quantify coastal foredune dynamics using nine topographic surveys performed near Egmond aan Zee, The Netherlands, between September 2011 and March 2014 using an unmanned aerial vehicle (UAV). The approximately 0.75-km long study site comprises a 30-100 m wide sandy beach and a 20-25 m high foredune, of which the higher parts are densely vegetated with European marram grass. Using a structure-from-motion workflow, the 200-500 photographs taken during each UAV flight were processed into a point cloud, from which a geo-referenced digital surface model with a 0.25 x 0.25 m resolution was subsequently computed. Our data set contains two dune-erosion events, including that due to storm Xaver (December 2013), which caused one of the highest surge levels in the southern North Sea region for the last decades. Dune erosion during both events varied alongshore from the destruction of embryonic dunes on the upper beach to the slumping of the entire dune face. During the first storm (January 2012), erosion volumes ranged from 5 m3/m in the (former) embryonic dune field to over 40 m3/m elsewhere. During the subsequent 11 (spring - autumn) months, the foredune accreted by (on average) 8 m3/m, again with substantial alongshore variability (0 - 20 m3/m). Intriguingly, volume changes during the 2012-2013 winter were minimal. We will compare the observed aeolian supply rates with model predictions and discuss reasons for their temporal variability. Funded by the Dutch Organisation for Scientific Research NWO.

  11. Luminescence dating of Holocene dune complexes along the shore of northern France (Picardy)

    NASA Astrophysics Data System (ADS)

    Lauer, Tobias; Frechen, Manfred; Meurisse-Fort, Murielle; Gosselin, Guillaume; van Vliet-Lanoë, Brigitte

    2010-05-01

    The Holocene dune and peat complexes along the shore of northern France (Picardy) had already been studied in detail by Meurisse et al. (2005) and Meurisse-Fort (2009). Information about the palaeodevelopment of those dune fields is hence given due to existing 14C data as well as by sedimentological and morphological analyses. Due to the results from radiocarbon dating, different types of aeolian bodies could be correlated along the Picardy coastline and a regional stratigraphic sequence could be established (Meurisse-Fort, 2009). The aim of the ongoing study is to get a higher chronological resolution for the different phases of dune activity in Picardy by luminescence dating what is a powerful tool to determine the time of last sunlight exposure of grains before burial (this information yields important information about dune movement). Samples for OSL dating were taken from dune bodies located in Tardinghen, Hardelot, Saint-Frieux and Saint-Gabriel. For dating, a single aliquot regenerative dose (SAR) protocol (Murray & Wintle 2003) is applied to coarse grained quartz. First tests concerning the signal intensity, the purity of the quartz OSL signal and the bleaching properties showed that quartz OSL dating works well for the dunes of the northern France coastline. The new luminescence ages will help to better unravel the phases of sand dune activity and stabilisation mainly controlled by climate changes and human impact. References: Meurisse, M., Van Vliet-Lanoë, B., Talon, B. & Recourt, P. (2005): Complexes dunaires et tourbeux holocènes du littoral du Nord de la France. - Geoscience, 337 : 675-684. Meurisse-Fort, M. (2009): Enregistrement haute résolution des massifs dunaires ; Manche, mer du Nord et Atlantique - Le rôle des tempêtes. Thèse de Doctorat soutenue en juin 2007, Université de Lille1. Coll. Recherches - Sciences (Sciences de la Terre). EPU-Publibook (ed.), Paris, 310 pp. Murray, A.S. & Wintle, A.G. (2003): The single aliquot regenerative dose protocol: potential for improvements in reliability. - Radiat. Meas., 37: 377-381.

  12. Modeling microwave backscatter and thermal emission from linear dune fields: Application to Titan

    NASA Astrophysics Data System (ADS)

    Le Gall, A.; Janssen, M. A.; Kirk, R. L.; Lorenz, R. D.

    2014-02-01

    We present an electromagnetic model that relates the microwave backscatter and thermal emission from linear dune fields to their compositional, physical (roughness, subsurface porosity/heterogeneity) and geometrical (slope, orientation) properties. This model shows the value of exploring these highly directional and geometrical features in light of both their backscattering cross-section and emissivity. Compared to Cassini concurrent radar and radiometry data acquired from October 2004 to June 2011 over Titan's dune fields, it provides clues to understand variations among dune regions on the largest Saturn's moon. In particular, it brings a formal support to the idea first advanced in Le Gall et al. (Le Gall, A., Janssen, M.A., Wye, L.C., Hayes, A.G., Radebaugh, J., Savage, C., Zebker, H., Lorenz, R.D., Lunine, J.I., Kirk, R.L., Lopes, R.M.C., Wall, S., Callahan, P., Stofan, E.R., Farr, T. and the Cassini Radar Team [2011]. Icarus 213, 608-624) that the size of the interdune valleys (relative to that of the dunes) varies across Titan as well as the diffuse scattering properties of these interdune areas due to different thickness of sand cover (i.e. bedrock contribution) or degree of compaction/heterogeneity of the sand cover. The Fensal and Belet dune fields, in particular, are quite different in terms of these properties. The comparison between the model and Cassini data also reveals the potential presence of structures, possibly small-superposed dunes, oriented perpendicular to the dune crests in the Aztlan region.

  13. Solar handbook

    SciTech Connect

    Not Available

    1981-01-01

    There is no best solar system for everybody. But there usually is a best solar system for each situation. This book describes a variety of working solar energy systems in Colorado, how much they cost, how well they have worked and factors that influence the solar decision-making process. Basics about how much solar energy is available and the principles used to collect it are discussed in the appendix section. Detailed information on these topics is widely available. Some solar systems operate by themselves. Some are controlled by thermostats, pumps and fans. Still others are controlled by people. The goal of this book is to give a variety of solar options to help one decide which, if any, is the most appropriate. Energy solar equipment cost data were obtained in 1977 when this research was conducted. Since that time, although the price of many energy resources has doubled, solar system costs have increased nearer to the pace of inflation. This trend will continue through the 1980s making investments in solar and energy conservation even more attractive today and tomorrow than investments made in 1977.

  14. A Dune Simulation Wind Tunnel for Studies of Lee Face Processes

    NASA Astrophysics Data System (ADS)

    Cupp, K.; Lancaster, N.; Nickling, W. G.

    2004-12-01

    Sand is deposited on the lee slope of dunes by grainfall, avalanching (grainflow), and wind ripple migration. These processes play major roles in the formation of aeolian cross strata. Grainfall is produced by saltating grains that are blown over the dune crest and fall on the lee slope. Avalanching occurs when sand on the lee slope fails and the resulting grainflow will deposit tongues of sand downslope. Lee slope deposits are often preserved in the rock record and an understanding of the conditions that produce them as well as avalanche frequency and magnitude could provide important information about dune morphology, sediment flux and availability, air flow, and the environment of deposition. Despite their importance there have been very few studies of grainfall and avalanching because the lee slope of dunes is a very fragile and easily disturbed environment. Designing research strategies to study these processes presents significant technical challenges. To overcome these obstacles construction and testing of a dune simulation wind tunnel was recently completed as a joint project between the Wind Erosion Laboratory, Department of Geography, University of Guelph and the Desert Research Institute. This wind tunnel contains a small, but true-scale sand dune that is 8.5 m long, 1.2 m high, and 1 m wide and is capable of producing wind speeds of 16 m/s at 30cm above the dune crest. The wind tunnel provides an opportunity to study lee slope processes in a well-constrained environment by controlling wind speeds and direction, dune geometry and composition, and allows for extensive instrumentation and close observation of depositional processes. Preliminary experiments in the dune simulation wind tunnel indicate that avalanche frequency is predictable: increased wind speeds resulted in more frequent avalanches. Avalanches commonly originate in the mid-lee slope region at or near the point of reattachment of the return cell caused by flow separation at the crest. Downslope saltation and/or reptation on the lee slope surface appear to slow at the point of reattachment and appears to be an important factor in the location of avalanche origination. Preliminary measurements of the distribution of sediment deposited by grainfall at three different wind speeds suggest a possible depositional bulge in the mid-lee slope region. Research supported by NSF EAR-0207833

  15. Linking marine resources to ecotonal shifts of water uptake by terrestrial dune vegetation.

    PubMed

    Greaver, Tara L; Sternberg, Leonel L da S

    2006-09-01

    As evidence mounts that sea levels are rising, it becomes increasingly important to understand the role of ocean water within terrestrial ecosystem dynamics. Coastal sand dunes are ecosystems that occur on the interface of land and sea. They are classic ecotones characterized by zonal distribution of vegetation in response to strong gradients of environmental factors from the ocean to the inland. Despite the proximity of the dune ecosystem to the ocean, it is generally assumed that all vegetation utilizes only freshwater and that water sources do not change across the ecotone. Evidence of ocean water uptake by vegetation would redefine the traditional interpretation of plant-water relations in the dune ecosystem and offer new ideas for assessing maritime influences on function and spatial distribution of plants across the dune. The purpose of this study was to identify sources of water (ocean, ground, and rain) taken up by vegetation using isotopic analysis of stem water and to evaluate water uptake patterns at the community level based on the distribution and assemblage of species. Three coastal dune systems located in southern Florida, USA, and the Bahamian bank/platform system were investigated. Plant distributions across the dune were zonal for 61-94% of the 18 most abundant species at each site. Species with their highest frequency on the fore dune (nearest the ocean) indicate ocean water uptake as evidenced by delta 18O values of stem water. In contrast, species most frequent in the back dune show no evidence of ocean water uptake. Analysis of species not grouped by frequency, but instead sampled along a transect from the ocean toward the inland, indicates that individuals from the vegetation assemblage closest to the ocean had a mixed water-harvesting strategy characterized by plants that may utilize ocean, ground-, and/or rainwater. In contrast, the inland vegetation relies mostly on rainwater. Our results show evidence supporting ocean water use by dune vegetation and demonstrate an exciting relationship between seawater and ecotonal shifts in plant function of a terrestrial ecosystem. PMID:16995639

  16. Assessing significant geomorphic changes and effectiveness of dynamic restoration in a coastal dune ecosystem

    NASA Astrophysics Data System (ADS)

    Walker, Ian J.; Eamer, Jordan B. R.; Darke, Ian B.

    2013-10-01

    A shift from restoring coastal dunes as stabilized landscapes toward more morphodynamic ecosystems is underway. This paper uses results from a recent case study where invasive vegetation was removed from a coastal dune complex in western Canada as a first step in a dynamic ecosystem restoration project. Spatial statistical methods, used in the natural sciences to quantify patterns of significant spatial-temporal changes, are reviewed and the local Moran's Ii spatial autocorrelation statistic is explored for detecting and assessing significant changes. Cluster maps of positive (depositional) and negative (erosional) changes were used to derive statistically significant volumetric changes within discrete geomorphic units (beach, foredune, transgressive dune) over one year following vegetation removal. All units experienced net increases in sediment budgets compared to a pre-restoration surface. The beach experienced the highest episodic erosion and volumetric change and greatest net annual sediment budget. Compared to the beach, the annual sediment budget of the foredune was 19% whereas the transgressive dune was 33%. The foredune recovered rapidly to initial erosion during restoration and subsequent natural events with consistently positive sediment volumes and attained a form similar to that pre-restoration. Aeolian deflation and sand bypassing through the foredune was greatest in the two months following vegetation removal and peak accretion in the transgressive dune resulted from depositional lobes extending from the foredune, smaller dunes migrating within the complex, and growth of a precipitation ridge along the eastern margin. Several methodological and logistical considerations for detecting significant change in dynamic dune landscapes are discussed including sampling strategy design, data normalization and control measures, and incorporating uncertainty and inherent spatial relations within acquired datasets to ensure accuracy and comparability of results. Generally underutilized in coastal geomorphology, spatial autocorrelation methods (e.g., local Moran's Ii) are recommended over spatially uniform threshold approaches for the ability to detect local change processes and explore hypotheses on spatial-temporal dynamics. Finally, several key geomorphic indicators, that are believed to aid in re-establishing ecological conditions and processes that favor more resilient and natural dune ecosystems, are identified for assessing the effectiveness of dynamic restoration projects including: increased aeolian activity, enlarged active sand surface area, positive sediment budgets, increased dune morphodynamics, improved geomorphic diversity, and enhanced geomorphic resilience. Although limited in temporal scope, the case study results show that the initial phase of the restoration treatment was effective in enhancing all indicators except for increasing sand surface area. Given decadal scale observations of climatic changes and longer-term eco-geomorphic trajectory toward stabilization in the region, however, it is unlikely that the geomorphic effectiveness of this restoration effort will continue without continued frequent treatment interventions.

  17. Modeling the effect of dune sorting on the river long profile

    NASA Astrophysics Data System (ADS)

    Blom, A.

    2012-12-01

    River dunes, which occur in low slope sand bed and sand-gravel bed rivers, generally show a downward coarsening pattern due to grain flows down their avalanche lee faces. These grain flows cause coarse particles to preferentially deposit at lower elevations of the lee face, while fines show a preference for its upper elevations. Before considering the effect of this dune sorting mechanism on the river long profile, let us first have a look at some general trends along the river profile. Tributaries increasing the river's water discharge in streamwise direction also cause a streamwise increase in flow depth. As under subcritical conditions mean dune height generally increases with increasing flow depth, the dune height shows a streamwise increase, as well. This means that also the standard deviation of bedform height increases in streamwise direction, as in earlier work it was found that the standard deviation of bedform height linearly increases with an increasing mean value of bedform height. As a result of this streamwise increase in standard deviation of dune height, the above-mentioned dune sorting then results in a loss of coarse particles to the lower elevations of the bed that are less and even rarely exposed to the flow. This loss of coarse particles to lower elevations thus increases the rate of fining in streamwise direction. As finer material is more easily transported downstream than coarser material, a smaller bed slope is required to transport the same amount of sediment downstream. This means that dune sorting adds to river profile concavity, compared to the combined effect of abrasion, selective transport and tributaries. A Hirano-type mass conservation model is presented that deals with dune sorting. The model includes two active layers: a bedform layer representing the sediment in the bedforms and a coarse layer representing the coarse and less mobile sediment underneath migrating bedforms. The exposure of the coarse layer is governed by the rate of sediment supply from upstream. By definition the sum of the exposure of both layers equals unity. The model accounts for vertical sediment fluxes due to grain flows down the bedform lee face and the formation of a less mobile coarse layer. The model with its vertical sediment fluxes is validated against earlier flume experiments. It deals well with the transition between a plane bed and a bedform-dominated bed. Applying the model to field scale confirms that dune sorting increases river profile concavity.

  18. Adaptation with gene flow across the landscape in a dune sunflower.

    PubMed

    Andrew, Rose L; Ostevik, Katherine L; Ebert, Daniel P; Rieseberg, Loren H

    2012-05-01

    Isolation by adaptation increases divergence at neutral loci when natural selection against immigrants reduces the rate of gene flow between different habitats. This can occur early in the process of adaptive divergence and is a key feature of ecological speciation. Despite the ability of isolation by distance (IBD) and other forms of landscape resistance to produce similar patterns of neutral divergence within species, few studies have used landscape genetics to control for these other forces. We have studied the divergence of Helianthus petiolaris ecotypes living in active sand dunes and adjacent non-dune habitat, using landscape genetics approaches, such as circuit theory and multiple regression of distance matrices, in addition to coalescent modelling. Divergence between habitats was significant, but not strong, and was shaped by IBD. We expected that increased resistance owing to patchy and unfavourable habitat in the dunes would contribute to divergence. Instead, we found that landscape resistance models with lower resistance in the dunes performed well as predictors of genetic distances among subpopulations. Nevertheless, habitat class remained a strong predictor of genetic distance when controlling for isolation by resistance and IBD. We also measured environmental variables at each site and confirmed that specific variables, especially soil nitrogen and vegetation cover, explained a greater proportion of variance in genetic distance than did landscape or the habitat classification alone. Asymmetry in effective population sizes and numbers of migrants per generation was detected using coalescent modelling with Bayesian inference, which is consistent with incipient ecological speciation being driven by the dune habitat. PMID:22429200

  19. [Spatial distribution patterns of dry sand layer on windward slope of dunes in Horqin Sand Land].

    PubMed

    Zong, Qin; Lamusa, A; Luo, Yong-Ming; Niu, Cun-Yang; Chen, Xue-Feng; Wang, Hai-Yang

    2012-04-01

    An observation was conducted on the thickness of dry sand layer on the windward slope of mobile and fixed dunes in west Horqin Sand Land, with the spatial distribution of the dry sand layer analyzed. Most of the dry sand layer had a thickness of 5-15 cm, and 92.0% and 98.6% of the mobile and fixed dunes had the dry sand layer with this thickness, respectively. Sand-fixing plants affected the thickness and the spatial distribution of the dry sand layer. There was an obvious spatial difference in the thickness of the dry sand layer on mobile dunes, being much thicker in the upper west areas while much thinner in the lower east areas. The thickness of the dry sand layer varied from 0 to 40 cm, with an average of 9.58 +/- 3.95 cm, and the CV was 41%. The variogram of the spatial distribution of dry sand layer on mobile dunes was expressed as spherical model, with a moderate spatial correlation. In contrast, the thickness of dry sand layer on fixed dunes showed obvious homogeneity, and had less spatial difference. The thickness of the dry sand layer ranged from 0 to 20 cm, with an average of 10.91 +/- 1.70 cm, and the CV was only 16%. PMID:22803448

  20. A scaling law for aeolian dunes on Mars, Venus, Earth, and for subaqueous ripples

    E-print Network

    Philippe Claudin; Bruno Andreotti

    2006-08-07

    The linear stability analysis of the equations governing the evolution of a flat sand bed submitted to a turbulent shear flow predicts that the wavelength $\\lambda$ at which the bed destabilises to form dunes should scale with the drag length $L_{\\rm drag} = \\frac{\\rho_s}{\\rho_f} d$. This scaling law is tested using existing and new measurements performed in water (subaqueous ripples), in air (aeolian dunes and fresh snow dunes), in a high pressure CO$_2$ wind tunnel reproducing conditions close to the Venus atmosphere and in the low pressure CO$_2$ martian atmosphere (martian dunes). A difficulty is to determine the diameter of saltating grains on Mars. A first estimate comes from photographs of aeolian ripples taken by the rovers Opportunity and Spirit, showing grains whose diameters are smaller than on Earth dunes. In addition we calculate the effect of cohesion and viscosity on the dynamic and static transport thresholds. It confirms that the small grains visualised by the rovers should be grains experiencing saltation. Finally, we show that, within error bars, the scaling of $\\lambda$ with $L_{\\rm drag}$ holds over almost five decades. We conclude with a discussion on the time scales and velocities at which these bed instabilities develop and propagate on Mars.

  1. Diversity of AMF associated with Ammophila arenaria ssp. arundinacea in Portuguese sand dunes.

    PubMed

    Rodríguez-Echeverría, Susana; Freitas, Helena

    2006-11-01

    Dune vegetation is essential for the formation and preservation of sand dunes and the protection of the coast line. Coastal sand dunes are harsh environments where arbuscular mycorrhizal fungi (AMF) play an important role in promoting plant establishment and growth. We present a study of the diversity of AMF associated with A. arenaria ssp. arundinacea in two locations of the Portuguese coast under a Mediterranean climate. These two locations were selected to compare a well-preserved dune system from a protected area with a degraded dune system from a public beach. AMF diversity was assessed mainly by cloning and sequencing of a fragment of the ribosomal SSU using the primer NS31 and AM1. Most of the 89 AMF clones obtained from the rhizosphere and roots of A. arenaria belonged to the genus Glomus, the largest clade within the Glomeromycota. Higher AMF diversity was found in the least disturbed site, in which spores of Scutellospora persica, Glomus constrictum and Glomus globiferum were found in the rhizosphere of A. arenaria. PMID:17043895

  2. Experimental and numerical study of turbulent flow associated with interacting barchan dunes

    NASA Astrophysics Data System (ADS)

    Barros, J. M., Jr.; Blois, G.; Anderson, W.; Tang, Z.; Best, J.; Christensen, K. T.

    2014-12-01

    Barchan dunes are naturally occurring three-dimensional topographic features that have been observed on the surface of several planets. They occur both in aeolian and in subaqueous environments. Barchans typically form in fields having a broad distribution in dune size and migration rates. This results in variable bedform spacing and eventually dynamic bedform-bedform interactions that involve morphodynamic processes (e.g. collision, merging, splitting). These processes are controlled by complex feedback mechanisms mutually linking three key elements: fluid flow, sediment transport and bed morphology. The aim of this work is to contribute to the understanding of the fluid-flow mechanisms responsible for the formation, migration and interaction of these dunes. To this end, we study the three-dimensional flow generated by the interactions between fixed barchan-dune models arranged in tandem in collision and ejection scenarios via experiments in an optically-accessible flow environment using planar particle-image velocimetry (PIV) measurements of the flow field. These measurements are complemented by targeted large-eddy simulations (LES) meant to provide a three-dimensional view of the flow processes for these fixed dune arrangements.

  3. Effects of Sand Dune Stabilization on the Spatial Pattern of Artemisia ordosica Population in Mu Us Desert, Northwest China.

    PubMed

    Zhang, Jiachen; Zhang, Yuqing; Fan, Dongqing; Qin, Shugao; Jia, Xin; Wu, Bin; Chen, Dong; Gao, Hao; Zhu, Linfeng

    2015-01-01

    Vegetation patterns are strongly influenced by sand mobility in desert ecosystems. However, little is known about the spatial patterns of Artemisia ordosica, a dominant shrub in the Mu Us desert of Northwest China, in relation to sand fixation. The aim of this study was to investigate and contrast the effects of sand dune stabilization on the population and spatial distribution of this desert shrub. Spatial autocorrelation, semi-variance analysis, and point-pattern analysis were used jointly in this study to investigate the spatial patterns of A. ordosica populations on dunes in Yanchi County of Ningxia, China. The results showed that the spatial autocorrelation and spatial heterogeneity declined gradually, and the distance between the clustered individuals shortened following sand dune fixation. Seedlings were more aggregated than adults in all stage of dune stabilization, and both were more aggregated on shifting sand dunes separately. Spatial associations of the seedlings with the adults were mostly positive at distances of 0-5 m in shifting sand dunes, and the spatial association changed from positive to neutral in semi-fixed sand dunes. The seedlings were spaced in an almost random pattern around the adults, and their distances from the adults did not seem to affect their locations in semi-fixed sand dunes. Furthermore, spatial associations of the seedlings with the adults were negative in the fixed sand dune. These findings demonstrate that sand stabilization is an important factor affecting the spatial patterns of A. ordosica populations in the Mu Us desert. These findings suggest that, strong association between individuals may be the mechanism to explain the spatial pattern formation at preliminary stage of dune fixation. Sand dune stabilization can change the spatial pattern of shrub population by weakening the spatial association between native shrub individuals, which may affect the development direction of desert shrubs. PMID:26102584

  4. Effects of Sand Dune Stabilization on the Spatial Pattern of Artemisia ordosica Population in Mu Us Desert, Northwest China

    PubMed Central

    Zhang, Jiachen; Zhang, Yuqing; Fan, Dongqing; Qin, Shugao; Jia, Xin; Wu, Bin; Chen, Dong; Gao, Hao; Zhu, Linfeng

    2015-01-01

    Vegetation patterns are strongly influenced by sand mobility in desert ecosystems. However, little is known about the spatial patterns of Artemisia ordosica, a dominant shrub in the Mu Us desert of Northwest China, in relation to sand fixation. The aim of this study was to investigate and contrast the effects of sand dune stabilization on the population and spatial distribution of this desert shrub. Spatial autocorrelation, semi-variance analysis, and point-pattern analysis were used jointly in this study to investigate the spatial patterns of A. ordosica populations on dunes in Yanchi County of Ningxia, China. The results showed that the spatial autocorrelation and spatial heterogeneity declined gradually, and the distance between the clustered individuals shortened following sand dune fixation. Seedlings were more aggregated than adults in all stage of dune stabilization, and both were more aggregated on shifting sand dunes separately. Spatial associations of the seedlings with the adults were mostly positive at distances of 0–5 m in shifting sand dunes, and the spatial association changed from positive to neutral in semi-fixed sand dunes. The seedlings were spaced in an almost random pattern around the adults, and their distances from the adults did not seem to affect their locations in semi-fixed sand dunes. Furthermore, spatial associations of the seedlings with the adults were negative in the fixed sand dune. These findings demonstrate that sand stabilization is an important factor affecting the spatial patterns of A. ordosica populations in the Mu Us desert. These findings suggest that, strong association between individuals may be the mechanism to explain the spatial pattern formation at preliminary stage of dune fixation. Sand dune stabilization can change the spatial pattern of shrub population by weakening the spatial association between native shrub individuals, which may affect the development direction of desert shrubs. PMID:26102584

  5. Solar greenhouse

    SciTech Connect

    Baldwin, R.E.

    1980-04-01

    A solar greenhouse is disclosed wherein plants are grown and utilized as collectors to absorb solar radiation and produce heat laden humidified air through the process of evapotranspiration. This humidified air is then further heated by solar energy. Energy is then extracted from the humidified air by cooling the air and condensing the water vapor within the air. The extracted heat can then be stored and utilized as required to heat the greenhouse and plants.

  6. Solar two

    NSDL National Science Digital Library

    Iowa Public Television. Explore More Project

    2004-01-01

    What is a method of active solar energy production? This article, part of a series about the future of energy, describes the use of large reflector power plants in the Mohave Desert. Students are introduced to the use of large solar reflectors to heat molten salt and produce energy for homes. Students view four photographs of different aspects of the solar complex. Copyright 2005 Eisenhower National Clearinghouse

  7. Solar Simulator

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Oriel Corporation's simulators have a high pressure xenon lamp whose reflected light is processed by an optical system to produce a uniform solar beam. Because of many different types of applications, the simulators must be adjustable to replicate many different areas of the solar radiation spectrum. Simulators are laboratory tools for such purposes as testing and calibrating solar cells, or other solar energy systems, testing dyes, paints and pigments, pharmaceuticals and cosmetic preparations, plant and animal studies, food and agriculture studies and oceanographic research.

  8. The sand seas of titan: Cassini RADAR observations of longitudinal dunes

    USGS Publications Warehouse

    Lorenz, R.D.; Wall, S.; Radebaugh, J.; Boubin, G.; Reffet, E.; Janssen, M.; Stofan, E.; Lopes, R.; Kirk, R.; Elachi, C.; Lunine, J.; Mitchell, K.; Paganelli, F.; Soderblom, L.; Wood, C.; Wye, L.; Zebker, H.; Anderson, Y.; Ostro, S.; Allison, M.; Boehmer, R.; Callahan, P.; Encrenaz, P.; Ori, G.G.; Francescetti, G.; Gim, Y.; Hamilton, G.; Hensley, S.; Johnson, W.; Kelleher, K.; Muhleman, D.; Picardi, G.; Posa, F.; Roth, L.; Seu, R.; Shaffer, S.; Stiles, B.; Vetrella, S.; Flamini, E.; West, R.

    2006-01-01

    The most recent Cassini RADAR images of Titan show widespread regions (up to 1500 kilometers by 200 kilometers) of near-parallel radar-dark linear features that appear to be seas of longitudinal dunes similar to those seen in the Namib desert on Earth. The Ku-band (2.17-centimeter wavelength) images show ???100-meter ridges consistent with duneforms and reveal flow interactions with underlying hills. The distribution and orientation of the dunes support a model of fluctuating surface winds of ???0.5 meter per second resulting from the combination of an eastward flow with a variable tidal wind. The existence of dunes also requires geological processes that create sand-sized (100- to 300-micrometer) particulates and a lack of persistent equatorial surface liquids to act as sand traps.

  9. The impact of Acacia saligna invasion on Italian coastal dune EC habitats.

    PubMed

    Del Vecchio, Silvia; Acosta, Alicia; Stanisci, Angela

    2013-07-01

    Alien species can represent a threat to several ecosystems because they can alter species relationships and ecosystem function. In Italy, Acacia saligna is a major invader and it forms dense stands in coastal environments. We analyze the impact of A. saligna in Italian Mediterranean dune systems. We randomly sampled coastal dune vegetation and investigated its floristic composition with ordination techniques. We compared species richness in invaded and non-invaded plots with rarefaction curves and analyzed the frequency of focal and ruderal species. A. saligna invaded Mediterranean scrub (habitats 2250* and 2260) and coastal Pinus dune wood (habitat 2270*) and it is particularly prevalent in sunny areas of habitat 2270*. We observed an increase in ruderal species and a decrease in focal species in the invaded plots of habitat 2270*. We suggest that more open and disturbed areas are more prone to A. saligna invasion. PMID:23932256

  10. Accident D’Electrisation et Hemorragie Cerebro-Meningee : A Propos D’une Observation

    PubMed Central

    Chaibdraa, A.; Medjellakh, M.S.; Saouli, A.; Bentakouk, M.C.

    2008-01-01

    Summary L'électrisation est un évènement accidentel qui diffère des autres pathologies occasionnant des brûlures graves, à cause de ses spécificités qui traduisent d'une part la destruction du revêtement cutané, mais également les effets directs ou indirects du courant électrique sur tout tissu de l'organisme rencontré lors de son passage, en particulier le tissu nerveux. Les manifestations neurologiques centrales sont nombreuses, en relation avec les effets de l'électricité sur le parenchyme cérébral ou une lésion associée à l'électrisation. Nous rapportons l'observation d'une hémorragie cérébro-meningée survenant au 3ème jour d'une électrisation grave. Cette complication est bien documentée dans la littérature traitant des accidents d'électrisation post-foudroiement. N'ayant pas rencontré de cas similaire publié lors des accidents dus au courant industriel, nous présentons cette observation, qui soulève le problème du mécanisme physiopathologique de survenue, difficile à trancher. PMID:21991125

  11. Recent debris flows on Mars: Seasonal observations of the Russell Crater dune field

    NASA Astrophysics Data System (ADS)

    Reiss, D.; Jaumann, R.

    2003-03-01

    Debris flows occur on slopes in the Russell Crater dune field. The morphology of the erosion features resembles terrestrial viscous slurry flows (mudflows) and suggests that a flow of fine-grained material mixed with liquid water might have been responsible for their formation. Seasonal MGS-TES and -MOC imagery based observations of the dune field show (1) an annual frosting and defrosting cycle and (2) that liquid H2O could be stable within a limited time period in the summer of the southern hemisphere. These observations lead to the conclusion that debris flows in the Russell Crater dune field may form under current climatic conditions by episodic or seasonal melting of small amounts of autumn/winter condensed water ice.

  12. Even low to medium nitrogen deposition impacts vegetation of dry, coastal dunes around the Baltic Sea.

    PubMed

    Remke, Eva; Brouwer, Emiel; Kooijman, Annemieke; Blindow, Irmgard; Esselink, Hans; Roelofs, Jan G M

    2009-03-01

    Coastal dunes around the Baltic Sea have received small amounts of atmospheric nitrogen and are rather pristine ecosystems in this respect. In 19 investigated dune sites the atmospheric wet nitrogen deposition is 3-8kg Nha(-1)yr(-1). The nitrogen content of Cladonia portentosa appeared to be a suitable biomonitor of these low to medium deposition levels. Comparison with EMEP-deposition data showed that Cladonia reflects the deposition history of the last 3-6 years. With increasing nitrogen load, we observed a shift from lichen-rich short grass vegetation towards species-poor vegetation dominated by the tall graminoid Carex arenaria. Plant species richness per field site, however, does not decrease directly with these low to medium N deposition loads, but with change in vegetation composition. Critical loads for acidic, dry coastal dunes might be lower than previously thought, in the range of 4-6kg Nha(-1)yr(-1) wet deposition. PMID:19095336

  13. Dune advance into a coastal forest, equatorial Brazil: A subsurface perspective

    NASA Astrophysics Data System (ADS)

    Buynevich, Ilya V.; Filho, Pedro Walfir M. Souza; Asp, Nils E.

    2010-06-01

    A large active parabolic dune along the coast of Pará State, northern Brazil, was analyzed using aerial photography and imaged with high-resolution ground-penetrating radar (GPR) to map the subsurface facies architecture and point-source anomalies. Most high-amplitude (8-10 dB) subsurface anomalies are correlated with partially buried mangrove trees along the leading edge (slipface) of the advancing dune. Profiles along a 200-m long basal stoss side of the dune reveal 66 targets, most of which lie below the water table and are thus inaccessible by other methods. Signal amplitudes of point-source anomalies are substantially higher than those associated with the reflections from continuous subsurface features (water table, sedimentary layers). When complemented with exposures and excavations, GPR provides the best means of rapid continuous imaging of the geological record of complex interactions between vegetation and aeolian deposition.

  14. Multiple dust sources in the Sahara Desert: The importance of sand dunes

    NASA Astrophysics Data System (ADS)

    Crouvi, Onn; Schepanski, Kerstin; Amit, Rivka; Gillespie, Alan R.; Enzel, Yehouda

    2012-07-01

    We determine the current sources of dust in the Sahara Desert using quantitative correlation between the number of days with dust storms (NDS), derived from remote-sensing data of high temporal resolution, with the distribution of the soil types and geomorphic units. During 2006-8 the source of over 90% of the NDS was found to be sand dunes, leptosols, calcisols, arenosols, and rock debris. In contrast to previous studies, only few dust storms originated from playas and dry lake beds. Land erodibility was estimated by regressing the NDS to the number of days with high-speed wind events, and was found to be high for sand dunes. Clay and fine-silt grains and aggregates are scarce in sand dunes, which most likely produce dust particles through aeolian abrasion of sand grains. Thus, saltating sand grains impacting clay aggregates on playa surfaces cannot be the sole process for generating dust in the Sahara.

  15. Perfluorinated compounds and polybrominated diphenyl ethers in great blue heron eggs from Indiana Dunes National Lakeshore, Indiana

    Microsoft Academic Search

    Thomas W. Custer; Kuruthachalam Kannan; Lin Tao; Abhinav R. Saxena; Bill Route

    2009-01-01

    In 2007 archived great blue heron (Ardea herodias) eggs collected from Indiana Dunes National Lakeshore, IN, (Indiana Dunes) in 1993 were analyzed for 11 perfluorinated compounds (PFCs) and 7 polybrominated diphenyl ethers (PBDEs). Concentrations of perfluorooctane sulfonate, the major contributor to total PFC concentrations, were below the toxicity thresholds estimated for bobwhite quail (Colinus virginianus) and mallards (Anas platyrhynchos), but

  16. Plants for Coastal Dunes of the Gulf and South Atlantic Coasts and Puerto Rico. Agriculture Information Bulletin 460.

    ERIC Educational Resources Information Center

    Craig, Robert M.

    Plants that have been identified as stabilizers and beautifiers of coastal dunes are described in this publication from the Soil Conservation Service (SCS). After years of tests and field trials, the SCS has singled out 43 plants as having good potential for dune revegetation based on their characteristics for erosion control, frequency of…

  17. Turbulent flow over a dune 289 Copyright 2005 John Wiley & Sons, Ltd. Earth Surf. Process. Landforms 30, 289304 (2005)

    E-print Network

    Venditti, Jeremy G.

    2005-01-01

    of turbulent flow over a mobile dune in a wide, low- gradient, alluvial reach of the Green River. Based as they are advected downstream. Fluid oscillations in the lee of the dune demonstrate Strouhal similarity between and the periodicity of surface boils was observed in the field. Copyright © 2005 John Wiley & Sons, Ltd. Keywords

  18. Recent aeolian dune change on Mars M.C. Bourke a,b,, K.S. Edgett c

    E-print Network

    Bourke, Mary C.

    Recent aeolian dune change on Mars M.C. Bourke a,b,, K.S. Edgett c , B.A. Cantor c a Planetary and then disappeared over a period of 3.04 Mars years (5.7 Earth years), while larger, neighboring dunes showed speed for saltation exceeded under present conditions on Mars, but that any sand that is available

  19. A Geologic Characterization of the Alongshore Variability in Beach-Dune Morphology: Padre Island National Seashore, Texas

    E-print Network

    Weymer, Bradley

    2012-07-16

    extreme storms, the beach-dune system should respond in different ways depending on the elevation and volume of the dunes relative to the storm surge. The purpose of this study is to use Ground-Penetrating Radar (GPR) and vibra-cores to investigate...

  20. Aridity in the monsoon zone as indicated by desert dune formation in the Gregory Lakes basin, northwestern Australia

    Microsoft Academic Search

    K. E. Fitzsimmons; G. H. Miller; N. A. Spooner; J. W. Magee

    2012-01-01

    Desert dunes within the monsoon-fed Gregory Lakes basin form valuable archives for Quaternary paleoenvironments, in a region where such records are scarce. Optically stimulated luminescence (OSL) chronologies from two dunes identify the timing of eolian processes, interpreted as a complex response to aridification and increased sediment availability during lake transgressions and associated fluvial activity. The earliest eolian deposition in our

  1. The reaction of some sand-dune plant species to experimentally imposed environmental change: a reductionist approach to stability

    Microsoft Academic Search

    R. R. Page; S. G. Vinha; A. D. Q. Agnew

    1985-01-01

    Coastal dunes in western Europe have long been under grazing and recreational pressure, but the vegetative cover appears to be remarkably resilient. In a series of experiments on Ynyslas Dunes, Cardigan Bay (Wales, U.K.), trampling, protection, fertiliser, and herbicide treatments were monitored using non-destructive and destructive sampling methods. This paper discusses the behaviour of 12 important species after these treatments

  2. The effect of recreational impacts on soil and vegetation of stabilised Coastal Dunes in the Sharon Park, Israel

    Microsoft Academic Search

    P Kutiel; H Zhevelev; R Harrison

    1999-01-01

    Coastal sand dunes are considered among the most susceptible habitats to recreational use. The aim of this study was to monitor the impact of visitor use on soil and annual plants on long-established trails in the stabilised coastal dunes of the Sharon Park, Israel. The results indicate that:1.The vegetation cover, height and species richness and diversity, as well as soil

  3. Response of the grasshopper Myrmeleotettix maculatus (Orthoptera: Acrididae) to invasion by the exotic moss Campylopus introflexus in acidic coastal dunes

    Microsoft Academic Search

    Jens Schirmel

    2011-01-01

    In Europe, acidic coastal dunes are threatened by the invasion of the exotic moss Campylopus introflexus. While the effect of the moss encroachment on the vegetation is well analysed, knowledge of possible impact on arthropods\\u000a is lacking. Thus, an experiment was conducted in acidic coastal dunes on the Baltic island of Hiddensee, Germany. Myrmeleotettix maculatus, a common Orthoptera species of

  4. Occupancy dynamics of wild rabbits (Oryctolagus cuniculus) in the coastal dunes of the Netherlands with imperfect detection

    Microsoft Academic Search

    Strien van A. J; J. J. A. Dekker; M. Straver; Meij van der T; L. L. Soldaat; A. Ehrenburg; Loon van E

    2011-01-01

    Context: Wild rabbits are considered a key species in the coastal dunes of the Netherlands, but populations have collapsed as a result of viral diseases. Aim: We studied to what extent population collapse led to local extinction and whether recolonisation of empty patches in the dunes happened. Methods: We investigated occupancy dynamics using data of 245 transects where rabbits were

  5. Identification and visualization of complex spatial pattern of coastal dune soil properties using GIS-based terrain analysis and geostatistics

    Microsoft Academic Search

    Keun Bae Yu; Soo Jin Park

    2008-01-01

    Coastal dunes display complex relationships among soil properties, vegetation, and geomorphology driven by marine and atmospheric dynamics. Considering topography as a fundamental control of the relations, this study investigated its influence on the spatial pattern of soil attributes in a coastal dune. We systematically collected 193 soil samples at intervals of 20 m from the Sindu coastal dunefield, South Korea,

  6. Short and long-term impacts of Acacia longifolia invasion on the belowground processes of a Mediterranean coastal dune ecosystem

    Microsoft Academic Search

    Elizabete Marchante; Annelise Kjøller; Sten Struwe; Helena Freitas

    2008-01-01

    Many coastal dune ecosystems in Portugal are invaded by the leguminous tree Acacia longifolia (Andrews) Willd. This exotic species was first introduced over one hundred years ago in an effort to mitigate dune erosion and loss of coastal landscapes. However, since then A. longifolia has spread to new areas, displacing the native vegetation. These invaded ecosystems contrast with the native

  7. Quantifying roughness density of vegetation and nebkha dunes in the Chihuahuan Desert, New Mexico, USA using terrestrial laser scanning

    NASA Astrophysics Data System (ADS)

    Nield, J. M.; Gillies, J. A.; Nickling, W. G.

    2012-04-01

    The roughness density and patterning of vegetation and nebkha dune elements in semi-arid environments has important implications for aeolian sediment transport. These individual elements often form complex spatial patterns, which are traditionally quantified as a single density or lambda value based on mean shrub height, breath and number of elements within a defined surface area. Measurements of height and width are undertaken using traditional surveying techniques or based on remote sensing imagery analysis, which are limited in their ability to capture the true frontal area of vegetation and dune elements, as well as the relationship between solid and flexible frontal area components. Here we use terrestrial laser scanning (TLS) to quantify three-dimensional plant and dune distributions, determining height and width values for individual elements in three different vegetation communities at the Jornada Experimental Range in the Chihuahuan Desert, New Mexico, USA. These communities include a creosote vegetated surface without dunes, an incipient mesquite nebkha dune environment and a mature mesquite nebkha dune site. TLS measurements compare well to manual measurements using DGPS and survey levels, but have the advantage that larger areas can be systematically quantified more efficiently. More importantly, TLS derived surface, dune and vegetation DEMs enable us to accurately characterise individual dune and shrub frontal areas under different wind directions, improving traditional lambda calculations.

  8. Impact of atmospheric circulation patterns on coastal dune dynamics, NW Spain

    NASA Astrophysics Data System (ADS)

    González-Villanueva, R.; Costas, S.; Pérez-Arlucea, M.; Jerez, S.; Trigo, R. M.

    2013-03-01

    Dunes in temperate latitudes have experienced a significant stabilization in recent times, essentially as a consequence of the expansion of dense vegetation cover. Yet, the causes for this gradual stabilization as well as the causes promoting antecedent aeolian mobilization remain poorly understood. The Traba coastal dune field, located in NW Spain, was examined to explore the causes inducing aeolian activity and subsequent stabilization since 1940. Morphological changes were identified through the combination of aerial photographs and geophysical techniques. Local wind field regimes were simulated using a regional climate model to obtain the variability of the most relevant modes of atmospheric circulation in the North Atlantic and European regions; North Atlantic Oscillation (NAO), Eastern Atlantic (EA) and Scandinavian (SCAND). This allows us to identify the impact of these circulation modes over dune dynamics. Results document an episode of aeolian activity during the 1950s followed by a gradual stabilization and fixation of the dune coincident with a decrease on storm and wind intensity. Yet, aeolian sand movement remained active in small areas (blowouts), occurring mainly during the summer. NE winds associated with a negative phase of the EA explain the movement of sand within the dune field under favorable conditions of sand supply. On the other hand, sand supply to the dune field from the beach was promoted by NW winds coincident with the summer negative phase of NAO. During winter, the negative NAO favored frequent SW winds associated with the passage of intense storms, which in turn explain sand remobilization from the beach making sediment available for the NW winds to blow inland. With this work, it is proven that to understand past and future aeolian activity requires critical consideration of the variability and impact of the two principal modes of atmospheric circulation in the North Atlantic (NAO and EA). The SCAND mode explaining a lower percentage of the local wind field variability was also included to achieve higher significance levels of explained variance.

  9. Denivation Features of Polar Dunes: An Earth Analogue for Morphological Indicators of Solid Water on Mars

    NASA Astrophysics Data System (ADS)

    McGowan, H. A.; Neil, D.

    2005-12-01

    The identification of sources of water on Mars will be critical to the successful exploration of the planet and the establishment of a permanent presence by humans. While the Martian polar ice caps contain up to 70% water by mass, the extreme climate of these regions means that they may not be suitable for habitation. As a result, other sites must be identified where access to water is possible. Recent evidence has emerged that suggests sand dunes on Mars may contain 40-50% water by mass (Bourke 2005). In this paper, we present niveo-aeolian features observed in the sand dunes of the Victoria Valley, Antarctica, which have long been considered an Earth analogue for those on Mars (Morris et al. 1972). These features include cornices of permafrosted sand in dune-crest deflation hollows, exposed erosion resistant frozen water and sand lenses, wet sand flows and seeps. We also report on the morphological characteristics of sand sink holes which form in chains above layers of buried, melting and/or sublimating snow. This process is apparently reliant on the melting of inter-grain ice bonds and subsequent formation of a dry mobile sand layer on the dune surface. These micro-morphological features associated with summertime denivation of the Victoria Valley sand dunes, which are 5 to 10 m high and several hundred meters in crest length, are too small to identify on air photographs, satellite imagery and LIDAR DEMS of these transverse barchanoid ridges. However, on Mars where sand dunes are 1 to 2 orders of magnitude larger, these features may be identifiable if solid water exists within them, as suggested by Bourke (2005). Perhaps of greater importance, they may indicate the presence of buried palaeo-snow layers which have been preserved beneath the erosion resistant permafrosted sand dunes on Mars. We believe that the formation and subsequent exposure of these snow layers is the primary cause of the denivation features present in the polar dunes of the Victoria Valley, Antarctica. References: Bourke, M.C. 2005: Water on Mars. The Halstead Lecture, British Association for the Advancement of Science, Trinity College, Dublin, September 2005. Morris, E.C., Mutch, T.A. and Holt, H.E. 1972: Atlas of geologic features in the Dry Valleys of South Victoria Land, Antarctica: Possible analogs of Martian surface features. Interagency report: Astrogeology 52. Prepared under NASA contract L-9718 by the Geological Survey.

  10. Centennial record of wind-field variations from a coastal dune (German Bight)

    NASA Astrophysics Data System (ADS)

    Lindhorst, Sebastian; Costas, Iria; Betzler, Christian

    2015-04-01

    We show that coastal wandering dunes bear a valuable climate record on time scales of seasons to years and can provide data on past wind-field variations for regions and/or time spans where no instrumental weather observations exist. To access this archive, we propose a combined approach, integrating sedimentological and geophysical methods. Sedimentary architecture and grain-size properties of a 32 m high parabolic dune on the barrier island Sylt (southern North Sea) were investigated using ground-penetrating radar (GPR) and laser-diffraction particle-size analyzer. A chronostratigraphic framework was established based on a series of historical aerial images covering the time period 1936 to 2009. GPR data reveal the internal sedimentary architecture of the dune with an effective resolution of about 0.3 m. Large inland-dipping foresets, being the result of the predominance of onshore winds, form the building block of the dune. The dune exhibits a complex internal architecture comprising numerous unconformities, i.e. gaps in the sedimentary record, slumps, top-lap geometries and shifting depocenters. Therefore, careful mapping of the dunes architectural elements prior to sediment sampling is essential. Grain-size statistics are based on 4900 samples taken equidistantly in a 245 m long trench parallel to the direction of dune movement. Sedimentological proxy data were calibrated using a time series of instrumental weather observations from a meteorological station, 2 km off the dune. These data reach back until the year 1950. Variations in wind speed are best reflected by the sorting of the grain-size distribution: periods of weaker winds result in better sorted sediments, whereas higher wind speeds yield a wider grain-size spectrum. This approach allows us to present a reconstruction of variations in the strength of onshore directed winds covering approximately the last 100 years. Our data show slightly increased wind speeds at the beginning of the 20th century, approx. until 1920, followed by a calmer period until the mid 1930s. Wind speeds in the time period 1935 to 1960 are elevated, comprable to the situation in the first quarter of the 20th century. The mid 1960s are characterized by a distinct increase in wind speed, wich stays elevated for the decades afterwards. These results are corroborated by published data on storminess in Northern Europe.

  11. The timing of climbing dune formation in southwestern Niger: fluvio-aeolian interactions and the rôle of sand supply

    NASA Astrophysics Data System (ADS)

    Rendell, Helen M.; Clarke, Michèle L.; Warren, Andrew; Chappell, Adrian

    2003-05-01

    Contemporary gully erosion has exposed sections in a climbing dune which is banked up against ferricrete terraces along the southern bank of the Niger River in southwestern Niger. The main sand transport direction in this area is from northeast to southwest, and the immediate source of the dune sand is the Niger River. Dune stratigraphy contains evidence of episodic, fluvially controlled accretion, separated by two palaeosols. Channel fills and stone stringers suggest occasional alluvial and colluvial reworking. Infra-red stimulated luminescence dating of the aeolian sands shows that dune development occurred episodically during the African Humid Period (15-5 ka), probably in response to an increase in sediment supply from the Niger River. Soil development occurred during the relatively short-lived period of enhanced aridity associated with the Younger Dryas, driven by weakening of the southwesterly monsoon circulation. Climate-driven dune accretion and further soil development occurred during the Holocene period.

  12. Solar Sprint

    ERIC Educational Resources Information Center

    Tabor, Richard; Anderson, Stephen

    2007-01-01

    In the "Solar Sprint" activity, students design, test, and race a solar-powered car built with Legos. The use of ratios is incorporated to simulate the actual work of scientists and engineers. This method encourages fourth-grade students to think about multiple variables and stimulates their curiosity when an activity doesn't come out as…

  13. Solar Structures

    NSDL National Science Digital Library

    IEEE

    2014-05-22

    In this activity, learners explore how the power of the sun can be harnessed to heat and cool a building. Learners work in teams of "engineers" to design and build their own solar houses out of everyday items. They test their solar house, evaluate their results, and present to the group.

  14. Solar boiler

    Microsoft Academic Search

    1980-01-01

    A solar boiler is described having a heat receiver element which substantially tracks the path of the sun for utilizing solar energy to heat a fluid passing through the boiler. A lens system is mounted on the upper portion of the heat receiver and concentrates the rays of the sun directly onto the upper surface of the receiver. Also included

  15. Solar Technologies

    ERIC Educational Resources Information Center

    von Hippel, Frank; Williams, Robert H.

    1975-01-01

    As fossil fuels decrease in availability and environmental concerns increase, soalr energy is becoming a potential major energy source. Already solar energy is used for space heating in homes. Proposals for solar-electric generating systems include land-based or ocean-based collectors and harnessing wind and wave power. Photosynthesis can also…

  16. Solar Power

    NSDL National Science Digital Library

    University of Colorado Boulder,

    In this activity, students learn how engineers use solar energy to heat buildings by investigating the thermal storage properties of some common materials: sand, salt, water and shredded paper. Students then evaluate the usefulness of each material as a thermal storage material to be used as the thermal mass in a passive solar building.

  17. Solar Week

    NSDL National Science Digital Library

    Solar Week is a week of online curriculum with daily topics on the Sun, including Sun as a Star, the Sun Close Up, Solar Activity, Eclipses, and Careers. Each day contains a game, an activity, topical questions, a related Life Science topic, teacher information, and an Ask the Scientist page.

  18. The morphology and flow fields of three-dimensional dunes, Rio Paraná, Argentina: results from simultaneous multibeam echo sounding and acoustic Doppler profiling

    Microsoft Academic Search

    D. R. Parsons; J. L. Best; R. Kostaschuk; O. Orfeo; R. J. Hardy

    2004-01-01

    Many studies of river dune dynamics have concentrated on two-dimensional (2D) bed features and their associated flow structures. This morphological simplification imposes inherent limitations on our interpretation and understanding of dune form and flow dynamics. For example, studies over 2D forms neglect the significant effect that lateral flows and secondary circulation may have on the flow structure and thus dune

  19. A wind tunnel simulation of the effects of stoss slope on the lee airflow pattern over a two-dimensional transverse dune

    Microsoft Academic Search

    Zhibao Dong; Guangqiang Qian; Wanyin Luo; Hongtao Wang

    2007-01-01

    Secondary airflow plays an important role in dune formation and development. The lee airflow pattern over transverse dunes is important in determining the shape, alignment, and spacing of dunes and is influenced significantly by the lee slope angle. In this paper we present the results of scaled wind tunnel simulations of the effects of stoss slope on the mean lee

  20. Solar Observations

    NSDL National Science Digital Library

    This is an activity involving observations of the Sun. Learners use pinhole cameras, solar telescopes, and/or solar viewing glasses to make solar observations, draw what they see, and identify sunspots, if they are present. Then, learners go online and compare their drawings to images obtained by the SOHO spacecraft. This activity requires the use a sunny outdoor location. This activity also require use of safe methods for observing the Sun, such as pinhole cameras, telescopes with proper solar filters attached, and/or viewing glasses that are designated for safe solar viewing. No one should look at the Sun unless one or more of these methods is used in a proper fashion.

  1. Solar Events

    NSDL National Science Digital Library

    This site is a joint effort of NOAA Research and the College of Education at the University of South Alabama. The goal of the site is to provide middle school science students and teachers with research and investigation experiences using on-line resources. This unit provides information and activities about the Sun, and solar events. Events such as solar flares, coronal holes, solar winds, and others are covered here. Students discover these events, their effects on humans and the Earth, gather solar data, and explain problems that occur with solar events. Parts of the unit include gathering information from other websites, applying the data gathered, and performing enrichment exercises. This site contains a downloadable teachers guide, student guide, and all activity sheets to make the unit complete

  2. Patterns of wind flow and aeolian deposition on a parabolic dune on the southeastern shore of Lake Michigan

    NASA Astrophysics Data System (ADS)

    Hansen, Edward; DeVries-Zimmerman, Suzanne; van Dijk, Deanna; Yurk, Brian

    2009-04-01

    Sand deposition and patterns of wind flow were studied on Green Mountain Beach (GMB) dune, a large Lake Michigan coastal dune that is transitional between a trough blowout and a fully-developed parabolic dune. Deposition pins were used to study the amount and pattern of aeolian sand deposition on the lee slopes of GMB dune over 20 months. In the late fall and winter, sand supported by ice between the grains accumulated on the upper- to mid-slopes, and became over-steepened (38°). During measurement periods containing two major storms with wind gusts up to 25 m/s, a total of 44% of the deposition on the lee slope occurred, compared to an average of 9% for comparable time periods between storms. Sand was delivered by mass movement to the lower slopes during the spring thaw. Very little sand was deposited on lee slopes during the summer. Maximum sand deposition occurred near the dune axis, oriented southwest-northeast, and then decreased rapidly along the limbs. Maximum sand transport and dune migration were oriented towards the northeast despite the dominant regional winds during the fall and winter being from the west and northwest. Arrays of anemometers and wind vanes were used to study airflow patterns within GMB dune on five different days. These studies indicate that steering of winds in the deflation area of the dune may be responsible for the northeasterly sediment transport. They also suggest, however, that the ability of the dune to steer winds, and thus, control the direction of sand transport and deposition, decreases when the angle between the oncoming winds and the dune axis is too great.

  3. Solar electricity and solar fuels

    NASA Astrophysics Data System (ADS)

    Spiers, David J.

    1989-04-01

    The nature of solar radiation and its variation with location is described. The distribution of energy in the solar spectrum places immediate limits on the theoretical efficiency of conversion processes, since practical absorbers cannot convert all wavelengths received to useful energy. The principles of solar energy conversion methods are described. Absorption of solar energy can give rise to direct electrical generation, heating, or chemical change. Electrical generation from sunlight can be achieved by photovoltaic systems directly or by thermal systems which use solar heat to drive a heat engine and generator. The technology used and under research for promising ways of producing electricity or fuel from solar energy is described. Photovoltaic technology is established today for remote area, small power applications, and photovoltaic module sales alone are over 100 million dollars per year at present. The photovoltaic market has grown steadily since the mid-1970's, as prices have fallen continuously. Future energy options are briefly described. The merits of a sustainable energy economy, based on renewable energy resources, including solar energy, are emphasized, as this seems to provide the only hope of eliminating the problems caused by the build-up of atmospheric carbon dioxide, acid rain pollution and nuclear waste disposal. There is no doubt that clean fuels which were derived from solar energy and either did not involve carbon dioxide and used atmospheric carbon dioxide as the source dioxide as the source of carbon would be a worthy ideal. Methods described could one day achieve this.

  4. Solar Oven

    NSDL National Science Digital Library

    The Concord Consortium

    2012-05-21

    In many rural parts of the world, people still cook with wood. They often must collect and carry the wood many miles on their backs. They also cut down trees and shrubs instead of letting them grow tall for shade. There is lots of sunshine in these areas, especially if the climate is dry, so a solar cooker would be very useful! Most solar cookers are ovens that convert sunlight into heat energy that is used for cooking. You will design a simple solar oven and improve the design by adding reflectors and insulation while testing heating power with a temperature sensor.

  5. Solar Eclipses

    NSDL National Science Digital Library

    Every now and then, the Sun, Earth, and Moon align so that, when viewed from the Earth, the Moon eclipses the Sun's light. Solar eclipses are fairly common- the Moon will block out some portion of the Sun at least twice a year. However, it is still a special event to be able to witness a total solar eclipse. This video segment discusses how solar eclipses happen, what factors affect whether the eclipse is partial or total, and and why eclpises are so difficult to witness. The segment is one minute fifty-three seconds in length.

  6. Solar Physics A Journal for Solar and Solar-

    E-print Network

    Padmanabhan, Janardhan

    1 23 Solar Physics A Journal for Solar and Solar- Stellar Research and the Study of Solar Terrestrial Physics ISSN 0038-0938 Volume 267 Number 2 Sol Phys (2010) 267:267-277 DOI 10.1007/s11207-010-9653- x Solar Polar Fields During Cycles 21??? 23: Correlation with Meridional Flows #12;1 23 Your article

  7. Adverse effects of recreation on sand dunes: A problem for coastal zone management

    Microsoft Academic Search

    Gay Vogt

    1979-01-01

    This paper deals with the conflict between two goals of coastal zone management: preservation and increased access to the shoreline for recreation purposes. Foot traffic and off?road vehicles are used as examples of recreational activities which can harm dune areas. A number of field studies, dealt with in the scientific literature, are cited, and the carrying capacity concept is discussed.

  8. EFFETS D'UNE CARENCE SVRE DE RIBOFLAVINE SUR LA POULE PONDEUSE : ORDRE DE PRIORIT

    E-print Network

    Paris-Sud XI, Université de

    EFFETS D'UNE CARENCE SÉVÈRE DE RIBOFLAVINE SUR LA POULE PONDEUSE : ORDRE DE PRIORITÉ ENTRE LES., Bellevue (Seine-et-Oise.) SOMMAIRE Privée de riboflavine, la poule pondeuse transfère cette vitamine dans l la ponte s'arrête. Le besoin vitaminique de ponte n'est donc pas prioritaire : la poule ne lui

  9. Spectral reflectance of biogenic crust developed on desert dune sand along the Israel-Egypt border

    Microsoft Academic Search

    A. Karnieli; H. Tsoar

    1995-01-01

    The effect of biogenic crust on imagery acquired by spaceborne sensors is demonstrated. The crust consists mostly of microphytes such as cyanobacteria. The macrophytes (higher vegetation) on the sand dunes are sparse and have a relatively low spectra! reflectance response. However, since a considerable ponton of the ground is covered by this biogenic crust, (which has a different spectral reflectance

  10. Morphological Analysis of Annual Recurrence of Dark Dune Spots on Southern Polar Region of Mars

    NASA Technical Reports Server (NTRS)

    Horvath, A.; Ganti, T.; Berczi, Sz.; Gesztesi, A.; Szathmary, E.

    2003-01-01

    Analysis of the Mars Global Surveyor narrow-angle images of the dark dune spots (DDSs) in three subsequent Martian winters and springs in Southern Polar Region resulted in the recognition that year by year DDSs reappeared on the same place with almost the same configuration. Comparison of the 1999 and 2001 high-resolution images showed a very interest recovery process.

  11. Nutrient and productivity relations of the dune grasses Ammophila arenaria and Elymus mollis

    Microsoft Academic Search

    Bruce Michael Pavlik

    1983-01-01

    A comparative study of blade photosynthesis and nitrogen use efficiency was made on the dune grasses Ammophila arenaria and Elymus mollis. In the laboratory, an open system gas analysis apparatus was used to examine the gas exchange characteristics of blades as influenced by nitrogen supply. Plants were grown under near-ambient coastal conditions in a greenhouse near Bodega Bay, California, and

  12. Inegalites d'oracle exactes pour la prediction d'une matrice en grande dimension

    E-print Network

    Paris-Sud XI, Université de

    In´egalit´es d'oracle exactes pour la pr´ediction d'une matrice en grande dimension St´ephane Ga propose sharp oracle inequalities for these algorithms in the noisy case, using a statistical learning travail, nous proposons des in´egalit´es d'oracle "exactes" pour ces algorithmes. References [1] Francis R

  13. Conservation justice in metropolitan Cape Town: A study at the Macassar Dunes Conservation Area

    E-print Network

    Silander Jr., John A.

    Conservation justice in metropolitan Cape Town: A study at the Macassar Dunes Conservation Area J xxxx Keywords: Conservation justice Community-based conservation South Africa Urban conservation Stakeholder analysis a b s t r a c t Conservation justice, a concept analogous to environmental justice

  14. tel-00490805,version1-9Jun2010 LA CONSTRUCTION D'UNE CULTURE POPULAIRE URBAINE

    E-print Network

    Paris-Sud XI, Université de

    appropriée à décrire le mouvement rap au Sénégal : en effet, si l'on considère comme David B. Coplan (1985 » (Coplan, 1992), alors le rap dakarois correspond à la définition d'une culture populaire ; il est produit contrairement à ce qu'observe David Coplan dans les ghettos de Johannesburg, il n'est pas associé à la lutte des

  15. STABILIT MCANIQUE D'UNE PHASE LIQUIDE COMPRISE DANS UN REVTEMENT COMPOSITE DE PROTECTION

    E-print Network

    Boyer, Edmond

    NIOBIUM CONTRE L'OXYDATION I. CAS D'UNE COUCHE DE VERRE VISQUEUX DÉPOSÉE SUR UN SUBSTRAT SOLIDE par J in which conditions the layer can satisfy both requirements of mechanical stability and fast self healing deposited on a gas turbine blade, but is possible in the case of a layer deposited on a static part

  16. The Great Sand Dunes Ecosystem Elk and Bison Carrying Capacity Model: Description and Scenario Results

    E-print Network

    Boone, Randall B.

    1 The Great Sand Dunes Ecosystem Elk and Bison Carrying Capacity Model: Description and Scenario instrumental in our completing the Elk and Bison Carrying Capacity Model. Specifically, the efforts of those of bison and elk and allowed us to create a detailed range map, are greatly appreciated. Information

  17. Human activity and potential impacts on dune breeding birds in the Alexandria coastal Dunefield

    Microsoft Academic Search

    J. J. Watson; G. I. H. Kerley; A. McLachlan

    1996-01-01

    Human use of coasts has increased considerably with increasing demand for recreational experiences, increased availability of off-road vehicles (ORVs) and population increase. Besides impacts on dune morphology and flora, humans and ORVs also affect the fauna. The Alexandria Dunefield in Algoa Bay comprises a 50 km sandy beach backed by a 2.1 km wide strip of dunefield. The dunefield is

  18. Giant aeolian dune size determined by the average depth of the atmospheric boundary layer

    E-print Network

    measurements and aerodynamic calculations, we show here that the growth of aeolian giant dunes, ascribed aerodynamic instability the initial wavelength ls of which is related to the length needed for sand transport is largely independent of the location and the season (Supplementary Information 1). In winter, the heat flux

  19. Morphology, dynamics, ecology and fauna of Arctotheca populifolia and Gazania rigens nabkha dunes

    Microsoft Academic Search

    Patrick Hesp; Anton McLachlan

    2000-01-01

    This paper examines some aspects of the development, growth and dynamics of nabkha (small, discrete dune hummocks) formed by two plant species, Arctotheca populifolia and Gazania rigens, including the colonization and utilization of the nabkha by terrestrial amphipods, Talorchestia capensis (Crustacea; Talitridae) and nematodes.Arctotheca populifolia has a prostrate growth habit, is relatively open, and has patches of bare sand scattered

  20. Proposition d'une dmarche de questionnements pour identifier et amliorer le Systme d'Intelligence

    E-print Network

    Paris-Sud XI, Université de

    Proposition d'une démarche de questionnements pour identifier et améliorer le Système d'Intelligence@oauife.edu.ng Computer Science and Engineering Department, Obafemi Awolowo University Ile-Ife (Nigeria) RÉSUMÉ. L'Intelligence présentons dans cet article, un SI supportant une démarche d'IE que nous baptisons Système d'Intelligence

  1. Projet Long Unitag Dveloppement d'une application Facebook compatible mobile et manipulation de QR Code

    E-print Network

    Grigoras, .Romulus

    Projet Long Unitag Développement d'une application Facebook compatible mobile et manipulation de QR création de QR Code pour les utilisateurs de Facebook, et notamment de QR Codes permettant d'accéder à certaines pages Facebook (ajout d'ami, like de pages, etc.). L'outil doit être simplissime à prendre en main

  2. Auto-incrmentation d'une base dysfonctionnelle de cas pour un systme

    E-print Network

    Boyer, Edmond

    Auto-incrémentation d'une base dysfonctionnelle de cas pour un système d'aide au diagnostic et à la mises en place sur une plateforme de e-maintenance. ABSTRACT. Case based reasoning is a methodology of intelligence artificial. Case-based Reasoning is an artificial intelligence method, widely used while solving

  3. Evapotranspiration of Artemisia ordosica Vegetation in Stabilized Arid Desert Dune in Shapotou, China

    Microsoft Academic Search

    X.-P. Wang; E.-S. Kang; J.-G. Zhang; X.-R. Li; R. Berndtsson

    2004-01-01

    More than 40 years of revegetation using mainly Artemisia ordosica, Hedysarum scoparium, and Caragana korshinskii at Shapotou Desert Experimental Research Station near Lanzhou has established a dwarf-shrub and herbaceous cover on the stabilized sand dunes. The evapotranspiration (ET) of the xerophyte dwarf-shrub A. ordosica plant vegetation was measured by the autoweighing lysimeter method during the growing seasons from 1990 to

  4. CHENOPODIUM LITTOREUM (CHENOPODIACEAE), A NEW GOOSEFOOT FROM DUNES OF SOUTH-CENTRAL COASTAL CALIFORNIA

    E-print Network

    Simpson, Michael G.

    . quinoa of South America (Mabberley 2008). The preparation of the Chenopodium treatment (ClemantsCHENOPODIUM LITTOREUM (CHENOPODIACEAE), A NEW GOOSEFOOT FROM DUNES OF SOUTH-CENTRAL COASTAL Diego, CA 92182, USA nuribpierce@gmail.com ABSTRACT Chenopodium littoreum is described as new. It had

  5. Soil microbial communities and activities in sand dunes of subtropical coastal forests

    Microsoft Academic Search

    Ed-Haun Chang; Chien-Teh Chen; Tsai-Huei Chen; Chih-Yu Chiu

    2011-01-01

    To understand the soil microbial activities and community structures in different forests in a sand-dune ecosystem, we conducted a study of 2 topographic conditions, upland and lowland, under a Casuarina forest. As well, in the lowland site, we compared forest soil microbial properties under 3 coastal forests (Casuarina, Hibiscus and mixed stand). The soil microbial biomass did not significantly differ

  6. LES PERSPECTIVES DE L'APICULTURE FRANAISE COMPTE RENDU D'UNE JOURNE D'TUDES.

    E-print Network

    Paris-Sud XI, Université de

    LES PERSPECTIVES DE L'APICULTURE FRANÇAISE COMPTE RENDU D'UNE JOURNÉE D'ÉTUDES. BURES l'Apiculture française ont été étudiées par un groupe de spécialistes réunis à Bures-sur-Yvette le apicoles français, qui dresse un tableau détaillé de la situation économique actuelle de l'apiculture de

  7. A test of a climatic index of dune mobility using measurements from the southwestern United States

    USGS Publications Warehouse

    Lancaster, N.; Helm, P.

    2000-01-01

    The climatic index of dune mobility developed by Lancaster (1988) has been applied to a variety of different environments. The index is, however, untested and unverified. We tested the index by comparison of values of the dune mobility index calculated from climate data with rates of sand transport measured at three stations in Arizona and New Mexico over the period 1985 to 1997. Our results show that changes in measured rates of sand transport closely parallel temporal changes in the dune mobility index. The mobility index is, however, a relatively poor predictor of the magnitude of actual sand transport on a year-to-year basis. This discrepancy is probably due to the fact that sand transport rates at these sites are strongly influenced by vegetation cover, the state of which may lag changes in annual precipitation. There is, however, a good relation between the mean annual mobility index and mean annual rates of sand transport. This indicates that the dune mobility index is a valid predictor of the long-term state of the aeolian system and can be used confidently for the purposes for which it was originally intended. Copyright (C) 2000 John Wiley and Sons, Ltd.

  8. TUDE DES MISSIONS DE RAYONS X ET DE NEUTRONS D'UNE DCHARGE NON CYLINDRIQUE FOCALISANTE

    E-print Network

    Boyer, Edmond

    339 ÉTUDE DES ÉMISSIONS DE RAYONS X ET DE NEUTRONS D'UNE DÉCHARGE NON CYLINDRIQUE FOCALISANTE octobre 1969) Résumé. 2014 Nous étudions les émissions de rayons X et de neutrons du plasma créé par une. L'étude de l'émission neutronique consiste à mesurer l'anisotropie de l'énergie des neutrons à l

  9. A Simple Model for Pattern Formation Caused in Sand Dunes by Downbursts

    NASA Astrophysics Data System (ADS)

    Matsuoka, Chihiro; Iwai, Yuki

    2012-09-01

    Pattern formation in sand dunes due to localized strong winds is investigated taking a downburst as an example. Extending the phenomenological model proposed by Nishimori et al. and taking into account the characteristic of powders, we calculate numerically the temporal evolution of sand patterns without using the hydrodynamic equations. We discuss the relation between the velocity distribution of a downburst and obtained patters qualitatively.

  10. Life and death in a Late Cretaceous dune field, Nemegt basin, Mongolia

    Microsoft Academic Search

    David B. Loope; Lowell Dingus; Carl C. Swisher III; Chuluun Minjin

    1998-01-01

    For more than 70 years, red sandstones of the Gobi Desert have yielded abundant articulated skeletons of Late Cretaceous dinosaurs, lizards, and mammals. At Ukhaa Tolgod, structureless sandstones are the only fossiliferous facies, and we present new evidence for deposition on dune-sand sourced alluvial fans that were built at the margins of stabilized eolian bedforms during mesic climatic episodes. In

  11. Morphology, niche segregation, and escape tactics in a sand dune lizard community

    Microsoft Academic Search

    O. Attum; P. Eason; G. Cobbs

    2007-01-01

    We examined patterns of co-existence for three species of scincid lizards (Sphenops sepsoides, Scincus scincus, and Chalcides ocellatus) in the simple sand dune habitat of North Sinai, Egypt. We first examined the morphological differences among the three species and compared their niche use and escape tactics in the context of their morphologies. Our results suggests that natural selection has favored

  12. Association of arbuscular mycorrhizal fungi with plants of coastal sand dunes of west coast of India

    Microsoft Academic Search

    K. R. BEENA; A. B. ARUN; N. S. RAVIRAJA; K. R. SRIDHAR

    An inventory of arbuscular mycorrhizal (AM) fungal status of 28 plant species belonging to 14 families established on the coastal sand dunes of southwest coast of India was performed. Roots of 23 plant species were colonized by AM fungi, whereas the rhizosphere of only 20 plant species possessed AM fungal spores. Canavalia cathartica had the highest root colonization (83%) by

  13. Effet d'une microonde sur la fission des excitons singulets dans le ttracne cristallin

    E-print Network

    Paris-Sud XI, Université de

    of fission singlet exciton processes by high power microwaves in crystalline tetracene. The observed effects indicate transitions between pair states of triplets produced by singlet exciton fission. The study643 Effet d'une microonde sur la fission des excitons singulets dans le tétracène cristallin J

  14. Dynamique d'une bulle cylindrique de cavitation : tude analytique et validation de la mthode

    E-print Network

    Dynamique d'une bulle cylindrique de cavitation : étude analytique et validation de la méthode. Introduction La présente étude a pour objectif dans un premier temps d'étudier analytiquement la cavitation permettra par la suite d'étudier la cavitation numériquement. La méthode numérique Lagrangienne SPH est

  15. Domestic Resistance: Gardening, Mothering, and Storytelling in Leslie Marmon Silko's "Gardens in the Dunes"

    ERIC Educational Resources Information Center

    Li, Stephanie

    2009-01-01

    Leslie Marmon Silko began her most recent work, "Gardens in the Dunes" (1999), intending to write a novel that would not be political. Following the publication of "Almanac of the Dead" (1992), which was simultaneously hailed as one of the most important books of the twentieth century and condemned for its angry self-righteousness, Silko…

  16. Spatial characterization, resolution, and volumetric change of coastal dunes using airborne LIDAR: Cape Hatteras, North Carolina

    Microsoft Academic Search

    Jason W. Woolard; Jeffrey D. Colby

    2002-01-01

    The technological advancement in topographic mapping known as airborne Light Detection and Ranging (LIDAR) allows researchers to gather highly accurate and densely sampled coastal elevation data at a rapid rate. The problem is to determine the optimal resolutions at which to represent coastal dunes for volumetric change analysis. This study uses digital elevation models (DEM) generated from LIDAR data and

  17. Measurements of Coupled Fluid and Sediment Motion Over Mobile Sand Dunes in a Laboratory Flume

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The relation between turbulent fluid motions and sediment particles over mobile sand dunes may be better understood by examining the time scales over which the quantities fluctuate. In laboratory experiments performed at the USDA-ARS-National Sedimentation Laboratory, profiles of acoustic backscatt...

  18. Time Scales in Turbulence and Sediment Concentration Over Mobile Sand Dunes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The relationship between turbulent fluid motions and sediment particles over mobile sand dunes may be better understood by examining the time scales over which the quantities fluctuate. In laboratory experiments performed at the USDA-ARS-National Sedimentation Laboratory, profiles of acoustic backs...

  19. La privatisation en Pologne : d'une approche plurielle aux difficultés de la privatisation de masse

    Microsoft Academic Search

    Jean-François Nivet

    1994-01-01

    [fre] La privatisation en Pologne : d'une approche plurielle aux difficultés de la privatisation de masse . La part du secteur privé dans le PIB polonais a franchi depuis 1 993 le seuil des 50 %. Cette progression provient en premier lieu du dynamisme de l'initiative privée qui s'est manifestée par la création ex nihilo de nouvelles entreprises. Le succès

  20. Le systme protolytique de Penicillium Roqueforti. IV. Proprits d'une carboxypeptidase acide.

    E-print Network

    Boyer, Edmond

    Le système protéolytique de Penicillium Roqueforti. IV. Propriétés d'une carboxypeptidase acide. J. Proteolytic system of Penicillium roqueforti. IV. Properties of an acid carboxypeptidase. An extracellular acid carboxypeptidase has been isolated from the culture medium of Penicillium roqueforti. The enzyme

  1. Mod elisation d'une diode a effet tunnel r esonant en r egime

    E-print Network

    Pinaud, Olivier

    Modâ?? elisation d'une diode â?? a effet tunnel râ?? esonant en râ?? egime transitoire Naoufel BEN ABDALLAH'interaction â?? electrostatique. A mathematical model for the transcient evolution of a resonant tunneling diode Abstract'â??electrons dans une diode a effet tunnel râ??esonant en râ??egime transitoire. Le modâ??ele prend en compte l

  2. MMOIRES ORIGINAUX 85 L'emploi d'une prparation de lipase prgastrique

    E-print Network

    Paris-Sud XI, Université de

    MÉMOIRES ORIGINAUX 85 L'emploi d'une préparation de lipase prégastrique dans la fabrication du'hydrolyse de la matière grasse peut être accrue par l'emploi, dans la fabrication, de préparations de lipase ou 76° C) détruit, en effet, une grande partie des lipases du lait [9, 25]. Il en va de même d

  3. CHACUN JETTE SON CHIEN De la fin d'une vie au XIXe

    E-print Network

    Paris-Sud XI, Université de

    CHACUN JETTE SON CHIEN De la fin d'une vie au XIXe siècle Éric Baratay « Alors Rose, qui pleurait, 18831 Le XIXe siècle est marqué par une forte croissance du nombre de chiens en France, qui seraient numérique n'est pas réservée aux chiens mais concerne tous les animaux domestiques ; elle est la conséquence

  4. Norbert Elias et les historiens franais. Histoire d'une rencontre

    E-print Network

    Paris-Sud XI, Université de

    'idée d'une autotransformation mentale de la société, proposée par Philipe Ariès et Michel Foucault, à of Philippe Ariès and Michel Foucault. They found in Elias' approach the missing link between the change les années 1980, un moment Elias chez les historiens français comme il y avait eu un moment Foucault

  5. Quaternary Science Reviews 22 (2003) 10591065 The timing of climbing dune formation in southwestern Niger

    E-print Network

    Clarke, Michèle

    2003-01-01

    ) and the Niger delta (Pastouret et al., 1978; Zabel et al., 2001). This paper focuses on the record of sand dune in southwestern Niger: fluvio-aeolian interactions and the r#ole of sand supply Helen M. Rendella, *, Mich"ele L terraces along the southern bank of the Niger River in southwestern Niger. The main sand transport

  6. Boundary processes between a desert sand dune community and an encroaching suburban landscape

    Microsoft Academic Search

    Cameron W. Barrows; Michael F. Allen; John T. Rotenberry

    2006-01-01

    In contrast to the body of work in more mesic habitats, few studies have examined boundary processes between natural and anthropogenic desert landscapes. Our research examined processes occurring at boundaries between a desert sand dune community and an encroaching suburban habitat. We measured responses to an anthropogenic boundary by species from multiple trophic levels, and incorporated measures of habitat suitability,

  7. Grain size discrimination between sands of desert and coastal dunes from northwestern Mexico

    Microsoft Academic Search

    Juan José Kasper-Zubillaga; Arturo Carranza-Edwards

    2005-01-01

    A textural study of grain-size distribution parameters (mean graphic size Mz, sorting ?, skewness Ski, kurtosis KG) was carried out in the state of Sonora, in NW Mexico. The aim was to distinguish between desert and coastal dunes based on the textural parameters of the sands. Sixty two sand samples were collected from the slip face and crest of linear

  8. Agents of change on Mars' northern dunes: CO2 ice and wind

    NASA Astrophysics Data System (ADS)

    Hansen, C. J.; Diniega, S.; Bridges, N.; Byrne, S.; Dundas, C.; McEwen, A.; Portyankina, G.

    2015-05-01

    Both wind and seasonal CO2 ice sculpt the dunes of Mars in today's climate. The High Resolution Imaging Science Experiment (HiRISE) on the Mars Reconnaissance Orbiter has returned extensive temporal coverage of changes on the north polar dunes for nearly four Mars years. The processes driving dune morphology changes such as the formation of new alcoves have been investigated. Considerable interannual variability has been observed. Most changes occur in the period of time when HiRISE cannot image: late summer and fall when light levels are too low to see subtle changes on the dunes and the polar hood obscures the surface, and winter when the cap is in polar night. This is consistent with seasonal control but does not allow us to directly differentiate between eolian processes vs. CO2 ice as the driving agent for alcove formation. Circumstantial evidence and observations of analog processes in the southern mid-latitudes however implicates processes associated with frost emplacement and removal.

  9. Peut-on parler d'une gestion globale de son capital santé ?

    Microsoft Academic Search

    Pascale Genier; Stéphane Jacobzone

    1998-01-01

    [fre] Peut-on parler d'une gestion globale de son capital santé ? . En première analyse, les comportements des individus par rapport à leur santé peuvent sembler assez cohérents : les consommateurs d'alcool ou de tabac surveillent moins leur poids ou leur alimentation, ont moins recours aux soins préventifs, achètent moins de pharmacie sans ordonnance. Il est alors tentant de supposer

  10. Are there habitats that contribute best to plant species diversity in coastal dunes?

    Microsoft Academic Search

    A. Acosta; M. L. Carranza; C. F. Izzi

    2009-01-01

    The following paper describes patterns of diversity across major habitat types in a relatively well preserved coastal dune system in central Italy. The research addresses the following questions: (a) whether different habitats defined on the base of a land cover map support similar levels of biodiversity in terms of vascular flora richness and number of rare and endangered species, and

  11. Dynamics and succession of coastal dune vegetation in the Eastern Cape, South Africa

    Microsoft Academic Search

    A. M. Avis; R. A. Lubke

    1996-01-01

    Mobile or partially vegetated dunefields dominate the Eastern Cape coastline, with dune slacks being conspicuously well vegetated. Earlier studies on the dynamics of these habitats suggested that greater soil moisture, reduced sand movement and salt spray favoured the establishment of more mesic species. Since an understanding of these successional processes has important management implications, more detailed studies to firstly describe

  12. Soil Characteristics of Rehabilitating and Unmined Coastal Dunes at Richards Bay

    Microsoft Academic Search

    R. J. van Aarde; A. M. Smit; A. S. Claassens

    The postmining rehabilitation of coastal sand dunes north of Richards Bay (28 8 43 9 S, 32 8 12 9 E), South Africa, is resulting in the development of a series of known- aged stands of vegetation dominated by Acacia karroo (sweet thorn). Other broad-leaved species are estab- lishing themselves in rehabilitating areas more than 12 years of age. Soils

  13. Habitat use of ponies and cattle foraging together in a coastal dune area

    Microsoft Academic Search

    Indra Lamoot; Carolien Meert; Maurice Hoffmann

    2005-01-01

    Grazing by large ungulates has been chosen as a management tool in scrub-dominated dune reserves at the Belgian coast. Due to morphological and physiological differences between cattle and ponies, differences in foraging behaviour and habitat use are expected, and these may result in a different impact on the spatially heterogeneous and nutrient-limited ecosystem. Grazing behaviour and habitat use of Shetland

  14. Ecohydrology and physiological water relations of vegetation along coastal dune ecotones on subtropical islands

    Microsoft Academic Search

    Tara L. Greaver

    2005-01-01

    As evidence mounts that sea levels are rising, it becomes increasingly important to understand the role of ocean water in the terrestrial hydrology of coastal ecosystems. In coastal dunes, ocean water may enter soils via salt spray through the surface or by ocean water intrusion into deeper vadose layers. However, it is unclear if ocean water enters terrestrial soil of

  15. Optimisation d'une transmission de donnes haut dbit sur un canal CPL

    E-print Network

    Paris-Sud XI, Université de

    Optimisation d'une transmission de données haut débit sur un canal CPL Naoufel OMRI Slaheddine'informations qui seront récupérées par un codage canal adéquat, puis optimiser l'estimateur afin d'atteindre un : Courants porteurs en ligne, CPL, Codage canal, Estimation du canal, Modulation multi-porteuse, OFDM, TEB. 1

  16. Les avocats tunisiens dans la Tunisie de Ben Ali : conomie politique d'une profession juridique

    E-print Network

    Paris-Sud XI, Université de

    Les avocats tunisiens dans la Tunisie de Ben Ali : économie politique d'une profession juridique autoritaire du président Ben Ali à mettre sous tutelle une profession qui, selon le discours de ses'autoréguler. Un premier dispositif consistait à donner aux avocats membres du parti de Ben Ali un accès

  17. A SUSTAINABLE APPROACH TO PRESERVE THE CHOCTAWHATCHEE COASTAL DUNE LAKES OF FLORIDA

    EPA Science Inventory

    Scattered along a 30 mile coastline just east of Destin, Florida, lies a series of 18 named coastal dune lakes distributed between Walton and Bay County. The lakes are irregularly shaped, typically shallow (2-6 m deep), located within a mile inland from the coast. The water is...

  18. 3D visualization of liquefaction-induced dune collapse in the Navajo Sandstone, Utah, USA

    NASA Astrophysics Data System (ADS)

    Ford, Colby; Nick, Kevin; Bryant, Gerald

    2015-04-01

    The eolian Navajo Sandstone outcrop on the Canyon Overlook Trail in Zion National Park in Southern Utah is dissected by modern erosion in a way which reveals a great deal of the three-dimensional architecture of a major soft-sediment deformation event. The feature is bounded below by a well-developed interdune complex made up of two superimposed carbonate lenses, above by an irregular truncational surface, and incorporates 3 - 10 m of sandstone over an approximately 2 km area. The material above the deformed interval is undeformed cross-bedded sandstone, with crossbeds downlapping onto the surface of truncation. The stratigraphic confinement of deformation and the irregularity of the upper bounding surface suggests a deformation process which created topography, which was in turn covered by the next upwind dune before it could be eroded flat. The deformed material itself is laterally segmented by a stacked succession of shear surfaces, which all strike approximately perpendicular to the paleo-wind direction and dip at decreasing angles in the down paleo-wind direction. These factors point to the collapse of a major dune into the downwind interdune area, likely initiated by liquefaction in the interdune complex. The foundering of the dune's toe into the liquefied area created a powerful lateral stress field which did not extend significantly into the subsurface. The dune collapse process has been used in the past to describe other soft-sediment deformation features in the Navajo Sandstone, but this site provides a wealth of physical details which were not previously associated with dune collapse. Shear surfaces originate in the interdune deposit as slip between laminae, then the cohesive muds provided support as they were thrust upward to angles of up to 50 degrees. The margins of the site also contain important paleoenvironmental indicators. Dinosaur tracks are exposed both at the extreme upwind and downwind margins of the interdune deposit in and slightly above the deformed interval. In addition, a smaller liquefaction feature is visible in the deposit just below the interdune deposit, far enough away from the main feature to suggest that it is a separate event, not directly caused by the dune collapse. It may have been an earlier episode, or was initiated by the same trigger, but it illustrates the susceptibility of this particular interdune to liquefaction. Details such as the confinement of deformation between irregular bounding surfaces, development of major shear planes, and nearby indicators of liquefaction may be used as new and more robust criteria for the recognition of dune collapse features in other localities and deposits.

  19. Sheet Flows, Avalanches, and Dune Evolution on Earth and Mars

    NASA Technical Reports Server (NTRS)

    2003-01-01

    This investigation is a collaboration between researchers at Cornell University, the University of Florida, and the University of Rennes 1, France. Flow modeling at Cornell University focused on mechanisms for the suspension and transport of wind-blown sand that are important in both terrestrial and Martian environments. These mechanisms include the saltation (or jumping) of grains, collisions between grains, and the interaction of grains with the velocity fluctuations of the turbulent wind. Of particular interest are sheet flows; these are relatively thin, highly concentrated regions of grains flowing near the ground under the influence of a strong turbulent wind. In them, the grains are suspended by interparticle collisions. Sheet flows may be relatively rare events, but they have the capacity to move great amounts of sand. In order to describe sheet flows, a turbulent mixture theory was formulated for particles in a fluid in which fluctuations in the volume fiaction of the particles take place on the scale of the turbulent eddies. Ensemble averaged equations for particle and fluid mass, momentum, and energy and fluid rate of dissipation were expressed in terms of Farve (concentration) averaged velocities and the associated velocity fluctuations. Correlations that describe the turbulent suspension of particles and dissipation of turbulent energy of both phases due to fluid particle interactions were modeled and boundary conditions at the bed and at the upper surface of the collisional flow were formulated. The boundary conditions at the upper surface were tested in a numerical simulation developed at the University of Florida. Steady and unsteady solutions for steady and unsteady fully-developed flows were obtained over a range of wind speeds fiom the lowest for which collisional between particles occurred to at which turbulent suspension is found to dominate collisional suspension. Below the value of the wind speed at which collisions between particles were unimportant, numerical solutions were obtained for the velocity distribution function and the resulting fields of concentration, particle and gas mean velocity, and particle shear stress for the steady two-dimensional saltation of spherical sand particles driven by a turbulent wind over a bed characterized by a simple relationship (the splash function) between the properties of incoming particles and those of the rebounding particles and other particles ejected fiom the bed. At the University of Rennes 1, experiments devoted to the characterization of the splash function for beds consisting of either random or ordered arrays of spheres in two- dimensions were completed. These indicated the role played by the packing geometry in the rebound and ejection of grains. Preliminary experiments on response of a three- dimensional collision bed to a collision with a single particle were performed. Data was taken with a single camera focused on the plane of collision. Here, for example, the decrease of the effective coefficient of restitution of the bed with an increase of the angle of incidence of the incoming particle has been measured. Other experiments on avalanches at Rennes studied the properties of the flows of particles that are responsible for the motion of the leeward side of a dune. In these, the dependence of the initiation of avalanches on the packing and depth of the particles was measured. Particle migration was studied in inclined flows of a binary mixture of disks and the mechanisms of diffision and segregation were isolated and characterized. The influence of side wall on dense, rapid inclined flows was measured and shown to be the reason why the angle of the free surface in such flows can exceed the static angle of repose. Future research will be devoted to a better understanding the transition between saltating (collisionless) and collisional flows as the wind speed the increases. This will involve the understanding of the evolution of the splash function as clisions with the bed become more numerous, more frequent, and more violent.

  20. Solar Nexus.

    ERIC Educational Resources Information Center

    Murphy, Jim

    1980-01-01

    The design team for the Solar Energy Research Institute (SERI) has pushed the state of the energy art to its current limits for the initial phase, with provisions for foreseeable and even speculative future applications. (Author/MLF)