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Sample records for dating impact-related deformation

  1. Electron Backscatter Diffraction (EBSD) Analysis and U-Pb Geochronology of the Oldest Lunar Zircon: Constraining Early Lunar Differentiation and Dating Impact-Related Deformation

    NASA Technical Reports Server (NTRS)

    Timms, Nick; Nemchin, Alexander; Grange, Marion; Reddy, Steve; Pidgeon, Bob; Geisler, Thorsten; Meyer, Chuck

    2009-01-01

    The evolution of the early moon was dominated by two processes (i) crystallization of the Lunar Magma Ocean (LMO) and differentiation of potassium-rare earth element-phosphorous-rich residual magma reservoir referred to as KREEP, and (ii) an intense meteorite bombardment referred to as lunar cataclysm . The exact timing of these processes is disputed, and resolution relies on collection and interpretation of precise age data. This study examines the microstructure and geochronology of zircon from lunar impact breccias collected during the Apollo 17 mission. A large zircon clast within lunar breccia 72215,195 shows sector zoning in optical microscopy, cathodoluminescence (CL) imaging and Raman mapping, and indicates that it was a relict fragment of a much larger magmatic grain. Sensitive high resolution ion microprobe (SHRIMP) U-Pb analysis of the zircon shows that U and Th concentration correlate with sector zoning, with darkest CL domains corresponding with high-U and Th (approx.150 and approx.100 ppm respectively), and the brightest-CL sectors containing approx.30-50 ppm U and approx.10-20 ppm Th. This indicates that variations in optical CL and Raman properties correspond to differential accumulation of alpha-radiation damage in each sector. Electron backscatter diffraction (EBSD) mapping shows that the quality of electron backscatter patterns (band contrast) varies with sector zoning, with the poorest quality patterns obtained from high-U and Th, dark-CL zones. EBSD mapping also reveals a deformation microstructure that is cryptic in optical, CL and Raman imaging. Two orthogonal sets of straight discrete and gradational low-angle boundaries accommodate approx.12 misorientation across the grain. The deformation bands are parallel to the crystallographic {a}-planes of the zircon, have misorientation axes parallel to the c-axis, and are geometrically consistent with formation by dislocation creep associated with <100>{010} slip. The deformation bands are unlike

  2. Resolution of impact-related microstructures in lunar zircon: A shock-deformation mechanism map

    NASA Astrophysics Data System (ADS)

    Timms, Nicholas E.; Reddy, Steven M.; Healy, David; Nemchin, Alexander A.; Grange, Marion L.; Pidgeon, Robert T.; Hart, Robert

    2012-01-01

    The microstructures of lunar zircon grains from breccia samples 72215, 73215, 73235, and 76295 collected during the Apollo 17 mission have been characterized via optical microscopy, cathodoluminescence imaging, and electron backscatter diffraction mapping. These zircon grains preserve deformation microstructures that show a wide range in style and complexity. Planar deformation features (PDFs) are documented in lunar zircon for the first time, and occur along {001}, {110}, and {112}, typically with 0.1-25 μm spacing. The widest PDFs associated with {112} contain microtwin lamellae with 65°/<110> misorientation relationships. Deformation bands parallel to {100} planes and irregular low-angle (<10°) boundaries most commonly have <001> misorientation axes. This geometry is consistent with a dislocation glide system with <100>{010} during dislocation creep. Nonplanar fractures, recrystallized domains with sharp, irregular interfaces, and localized annealing textures along fractures are also observed. No occurrences of reidite were detected. Shock-deformation microstructures in zircon are explained in terms of elastic anisotropy of zircon. PDFs form along a limited number of specific {hkl} planes that are perpendicular to directions of high Young's modulus, suggesting that PDFs are likely to be planes of longitudinal lattice damage. Twinned {112} PDFs also contain directions of high shear modulus. A conceptual model is proposed for the development of different deformation microstructures during an impact event. This “shock-deformation mechanism map” is used to explain the relative timing, conditions, and complexity relationships between impact-related deformation microstructures in zircon.

  3. Impact-Related Deformation Features in Cherts from Terrestrial Impact Structures

    NASA Astrophysics Data System (ADS)

    Schmieder, M.; Buchner, E.; Reimold, W. U.

    2011-03-01

    A preliminary review of impact-induced and potentially impact-related microdeformation features in cherts from a number of sedimentary-hosted terrestrial impact structures (Jebel Waqf as Suwwan, Steinheim, Kentland, and Crooked Creek) is presented.

  4. Impact-Related Deformation of PDFs in Quartz: When Identification of True PDFs Becomes Challenging

    NASA Astrophysics Data System (ADS)

    Pittarello, L.; Burlet, C.; Raes, M.; Koeberl, C.; Debaille, V.; Terryn, H.; Claeys, Ph.

    2015-09-01

    Electron microscopy on shocked quartz from the El'gygytgyn impact structure has revealed syn-impact, crystal deformation that has overprinted PDFs and hampers PDFs correct indexation by means of optical microscope and U-stage.

  5. Impact-related noncoaxial deformation in the Pułtusk H chondrite inferred from petrofabric analysis

    NASA Astrophysics Data System (ADS)

    Krzesińska, Agata; Gattacceca, Jérôme; Friedrich, Jon M.; Rochette, Pierre

    2015-03-01

    Petrofabrics in chondrites have the potential to yield important information on the impact evolution of chondritic parent asteroids, but studies involving chondritic petrofabrics are scarce. We undertook an analysis of the Pułtusk H chondrite regolith breccia. Measurements of anisotropy of magnetic susceptibility and quantitative tomographic examination of metal grains are presented here and the results are compared with petrographic observations. The major fabric elements are in Pułtusk shear fractures cutting the light-colored chondritic clasts as well as brittly and semibrittly deformed, cataclased fragments in dark matrix of regolith breccia. Cataclasis is accompanied by rotation of silicate grains and frictional melting. Fabric of metal grains in chondrite is well defined and coherently oriented over the breccia, both in the clasts and in the cataclastic matrix. Metal grains have prolate shapes and they are arranged into foliation plane and lineation direction, both of which are spatially related and kinematically compatible to shear-dominated deformational features. We argue that the fabric of Pułtusk was formed in response to impact-related noncoaxial shear strain. Deformation promoted brittle cataclastic processes and shearing of silicates, and, simultaneously, allowed for ductile metal to develop foliation and lineation. We suggest that plastic flow is the most probable mechanism for the deformation of metal grains in the shear-dominated strain field. The process led also to the formation of large metal nodules and bands in the dark matrix of breccia.

  6. Isotopic dating of strain fringe increments: duration and rates of deformation in shear zones

    PubMed

    Muller; Aerden; Halliday

    2000-06-23

    The time scales over which deformation in the Earth's crust remains localized in shear zones are poorly known, as are the associated strain rates. We have determined the longevity and rates of deformation using rubidium-strontium (Rb-Sr) microsampling dating of increments of fibrous strain fringes from a Pyrenean shear zone. The fibers grew quasi-continuously through a protracted deformation history between 87 and 50 million years ago, over a period comparable to that of an orogeny. During a short interval between 66 and 62 million years, a rise in strain rate from 1.1 x 10(-15) to 7. 7 x 10(-15) seconds(-1) occurred. This acceleration correlates with an abrupt change in fiber-growth direction and a stress-field inversion from gravitational collapse to renewed horizontal crustal shortening. PMID:10864865

  7. Structural analysis of the collar of the Vredefort Dome, South Africa—Significance for impact-related deformation and central uplift formation

    NASA Astrophysics Data System (ADS)

    Wieland, Frank; Gibson, Roger L.; Reimold, Wolf Uwe

    2005-10-01

    Landsat TM, aerial photograph image analysis, and field mapping of Witwatersrand supergroup meta-sedimentary strata in the collar of the Vredefort Dome reveals a highly heterogeneous internal structure involving folds, faults, fractures, and melt breccias that are interpreted as the product of shock deformation and central uplift formation during the 2.02 Ga Vredefort impact event. Broadly radially oriented symmetric and asymmetric folds with wavelengths ranging from tens of meters to kilometers and conjugate radial to oblique faults with strike-slip displacements of, typically, tens to hundreds of meters accommodated tangential shortening of the collar of the dome that decreased from ˜17% at a radius from the dome center of 21 km to <5% at a radius of 29 km. Ubiquitous shear fractures containing pseudotachylitic breccia, particularly in the metapelitic units, display local slip senses consistent with either tangential shortening or tangential extension; however, it is uncertain whether they formed at the same time as the larger faults or earlier, during the shock pulse. In addition to shatter cones, quartzite units show two fracture types—a cmspaced rhomboidal to orthogonal type that may be the product of shock-induced deformation and later joints accomplishing tangential and radial extension. The occurrence of pseudotachylitic breccia within some of these later joints, and the presence of radial and tangential dikes of impact melt rock, confirm the impact timing of these features and are suggestive of late-stage collapse of the central uplift.

  8. 10Be surface exposure dating reveals strong active deformation in the central Andean backarc interior

    NASA Astrophysics Data System (ADS)

    García Morabito, Ezequiel; Terrizzano, Carla; Zech, Roland; Willett, Sean; Yamin, Marcela; Haghipour, Negar; Wuethrich, Lorenz; Christl, Marcus; María Cortes, José; Ramos, Victor

    2016-04-01

    Understanding the deformation associated with active thrust wedges is essential to evaluate seismic hazard. How is active faulting distributed throughout the wedge, and how much deformation is taken up by individual structures? We address these questions for our study region, the central Andean backarc of Argentina. We combined a structural and geomorphological approach with surface exposure dating (10Be) of alluvial fans and strath terraces in two key localities at ~32° S: the Cerro Salinas, located in the active orogenic front of the Precordillera, and the Barreal block in the interior of the Andean mountain range. We analysed 22 surface samples and 6 depth profiles. At the thrust front, the oldest terrace (T1) yields an age of 100-130 ka, the intermediate terrace (T2) between 40-95 ka, and the youngest terrace (T3) an age of ~20 ka. In the Andean interior, T1´ dates to 117-146 ka, T2´ to ~70 ka, and T3´ to ~20 ka, all calculations assuming negligible erosion and using the scaling scheme for spallation based on Lal 1991, Stone 2000. Vertical slip rates of fault offsets are 0.3-0.5 mm/yr and of 0.6-1.2 mm/yr at the thrust front and in the Andean interior, respectively. Our results highlight: i) fault activity related to the growth of the Andean orogenic wedge is not only limited to a narrow thrust front zone. Internal structures have been active during the last 150 ka, ii) deformation rates in the Andean interior are comparable or even higher that those estimated and reported along the emerging thrust front, iii) distribution of active faulting seems to account for unsteady state conditions, and iv) seismic hazards may be more relevant in the internal parts of the Andean orogen than assumed so far. References Lal, D., 1991: Cosmic ray labeling of erosion surfaces: In situ nuclide production rates and erosion models. Earth and Planetary Science Letters 104: 424-439. Stone, J.O., 2000: Air pressure and cosmogenic isotope production. Journal of Geophysical

  9. Dating deformation - Lifetimes of phases vs. lifetimes of crystals and pulsed motion along fault zones

    NASA Astrophysics Data System (ADS)

    Chakraborty, Sumit

    2016-04-01

    The timing of movement in a fault zone may be obtained either by dating minerals that grow in these zones or by determining the pressure - temperature - time history of the blocks lying on either side of the zone. Interpreting dates of minerals in the fault zone itself requires the assumption that the minerals grew during or close to the timing of movement, that there was a single pulse of movement, or that the ages have not been reset by later pulses of movement. Determining the P-T-t history of the overlying and underlying blocks, on the other hand, may provide a more comprehensive history but it is essential to determine exactly what stage of a P-T history is dated by a given isotopic system. In addition, information on lateral contiguity is missing from such data. Strengths and weaknesses of both approaches may be illustrated using a case study from the MCT zone in the Sikkim Himalaya. Lu-Hf dates of garnets from the underlying lesser Himalayan (LH) and overlying higher Himalayan (HH) rocks yield a systematic picture (Anczkiewicz et al., 2015), but the significance of these dates using the same isotopic system and same mineral are different in the two blocks. In the lower grade lesser Himalayan rocks, fractionated trace element patterns formed during growth of garnet are preserved. As a result, bulk of the Lu occurs at the cores of garnets and the well-defined ages mark the initiation of garnet growth along the prograde path rather than the peak of metamorphism in these rocks. In the higher grade HH rocks, although metamorphic temperatures were higher (750 - 800 °C) they did not cross the closure temperature of Lu and/or Hf diffusion in garnet. In these pelitic bulk compositions, growth of garnet is expected to have occurred at garnet grade conditions (~ 500 °C). Nevertheless, in the presence of melt and deformation, there is evidence that the garnet grains recrystallized and Lu was more homogeneously distributed within the grain. Therefore, the ages from

  10. Influence of deformation and fluids on Ar retention in white mica: Dating the Dover Fault, Newfoundland Appalachians

    NASA Astrophysics Data System (ADS)

    Kellett, Dawn A.; Warren, Clare; Larson, Kyle P.; Zwingmann, Horst; van Staal, Cees R.; Rogers, Neil

    2016-06-01

    White mica 40Ar/39Ar analyses may provide useful constraints on the timing of tectonic processes, but complex geological and thermal histories can perturb Ar systematics in a variety of ways. Ductile shear zones represent excellent case studies for exploring the link(s) between dynamic re-/neo-crystallization of white mica and coeval enhanced fluid flow, and their effect on 40Ar/39Ar dates. White mica 40Ar/39Ar dates were collected from compositionally similar granites that record different episodes of deformation with proximity to the Dover Fault, a terrane-bounding strike-slip shear zone in the Appalachian orogen, Newfoundland, Canada. 40Ar/39Ar data were collected in situ by laser ablation and by step heating single crystals. Results were compared to each other and against complementary U-Pb zircon and monazite, and K-Ar fault gouge analysis. Although step-heat 40Ar/39Ar is a widely applied method in orogenic settings, this dataset shows that relatively flat step-heat 40Ar/39Ar spectra are in contradiction with wide spreads in in-situ40Ar/39Ar dates from the same samples, and that plateau dates in some cases yielded mixed dates of equivocal geological significance. This result indicates that the step-wise release of Ar from white mica likely homogenizes and obscures spatially-controlled Ar isotope reservoirs in white mica from sheared rocks. In contrast, in situ laser ablation 40Ar/39Ar analysis preserves the spatial resolution of 40Ar reservoirs that have been variably reset by deformation and fluid interaction. This study therefore suggests that laser ablation is the best method for dating the timing of deformation recorded by white mica. Final interpretation of results should be guided by microstructural analysis, estimation of deformation temperature, chemical characterization of white mica, and complementary chronometers. Overall the dataset shows that granitic protoliths were emplaced between 430 and 422 Ma (U-Pb zircon). High strain deformation along the

  11. Amino acid epimerization dating of Quaternary coastal deformation in SE Iberian Peninsula: The region between Aguas and Antas Rivers' mouths

    NASA Astrophysics Data System (ADS)

    Torres, Trinidad; Ortiz, José E.; Sánchez-Palencia, Yolanda

    2016-05-01

    The coastal area between the mouths of the Aguas and Antas Rivers presents a deformed system of raised marine deposits, some of which have been strongly affected by active tectonics. The use of amino acid epimerization dating of Glycymeris shells from raised coastal deposits allowed determining the age of these marine deposits, all of them linked to highstand sea levels in the Mediterranean realm, with ages between MIS 11 and MIS 1. These results allowed corroborating the age of some previously studied sites, and using new sampling sites, the general aminostratigraphy for the Quaternary raised marine deposits on the Mediterranean coast was confirmed. The main deformation event took place after MIS 11 and continued until MIS 5, and was linked to the activity of the Palomares Fault.

  12. Dating mylonitic deformation by the Ar-40-Ar-39 method: An example from the Norumbega fault zone, Maine

    NASA Astrophysics Data System (ADS)

    West, David P., Jr.; Lux, Daniel R.

    1993-12-01

    Ar-40/Ar-39 dating methods can be used to date deformational events effectively, as long as several important criteria are met. First and foremost, samples must be well characterized prior to analysis. Dynamic recrystallization must have occurred at or below the closure temperature of the mineral to be analyzed. Regional cooling patterns must also be established through detailed thermochronology so that mineral ages and age spectra from the deformed rocks can be compared to regional cooling ages of the same mineral. Finally, the effects of excess argon must be negligible.

  13. Pleistocene deformation and landscape evolution in the Tehran plain: results from tectonic geomorphology and TCN-dating

    NASA Astrophysics Data System (ADS)

    Landgraf, Angela; Benedetti, Lucilla; Braucher, Regis; Bourles, Didier; Ballato, Paolo; Strecker, Manfred R.; Friedrich, Anke M.; Tabatabaei, Saeid H.; Shahpasandzadeh, Majid

    2010-05-01

    The ENE-to NW-striking North Tehran Fault (NTF) is an active frontal thrust that delimits the Alborz Mountain range to the south with an up to 2000 m topographic break with respect to the adjacent Tehran plain. Eocene rocks of the Alborz range are thrust over Neogene and Quaternary sediments of the Tehran plain. The NTF constitutes right-stepping segments and merges to the east with the active Mosha-Fasham strike-slip fault (MFF). The historical record of destructive earthquakes lists numerous events on faults in this region, but instrumentally recorded seismicity appears to be focused on the eastern segment of the MFF. The youngest manifestations of deformation along the eastern segment of the NTF and the MFF are faults with normal and left-lateral oblique normal fault kinematics. Along the NTF, this youngest phase of activity is documented by meter-scale fault gouge zones, multiple colluvial wedges with drag features, subsidiary faults, and numerous striated and rotated conglomeratic clasts. Rupture traces and filled extensional cracks reaching the surface document the seismogenic nature of these features. The middle and western segments of the NTF, however, show evidence for Quaternary left-oblique and pure thrusting. These faults displace Quaternary fluvial sediments and alluvial fan deposits. This pattern of deformation also characterizes the Tehran plain in the southern foreland of the Alborz mountains. The western sector of the plain is deforming by (partly blind) thrusting, as manifested by a segmented and internally deformed anticline and abandoned and diverted channels on both sides of this structure. The recency of faulting at depth and corresponding surface deformation can be inferred from 10Be-dating of an adjacent river terrace and possibly postdates 25ka. The central sector of the plain, which forms the substratum of the Tehran megacity, is affected by thrusting and left-lateral strike-slip faulting and contains several sets of uplifted fluvial

  14. Age of the Druksiai-Polotsk deformation zone, Lithuania: a U-Pb dating of metamorphic titanite

    NASA Astrophysics Data System (ADS)

    Vejelyte, Irma; Bogdanova, Svetlana; Salnikova, Ekaterina

    2010-05-01

    The studied Druksiai-Polotsk deformation zone (DPDZ) transects the East Lithuanian Domain (ELD), representing the southern margin of the major Polotsk-Kurzeme zone of faulting in the Baltic-Belarus region. The DPDZ is of 35-40 km wide, E-W trending, and marked well by linear gravity and magnetic anomalies. The crystalline rocks within the DPDZ are granulites, biotite granites, and migmatites, the latter consisting of amphibole-plagioclase paleo- and mesosomes, and plagioclase-quartz-biotite±microcline±amphibole neosomes. Because of ductile shearing gneisses, augen mylonites, mylonites and ultramylonites were produced while tectonic breccias and pseudotachyllite were formed by later brittle deformation. According to geophysical data and the surface morphology of the crystalline basement, a horst-graben structure have recognized along the DPDZ. The graben is filled with Vendian, Cambrian, Ordovician, Silurian and Devonian deposits. A U-Pb dating of titanite from an augen granitoid mylonite in the DPDZ has yielded a concordant age of 1534±9 Ma. This light brown titanite follows the folation in the host rock and was obviously formed during retrogression from amphibolite- to epidote-amphibolite facies and coeval mylonitization. Shear zones of the same age are known in southern and central Sweden and in NE Poland. These E-W trending deformation zones accommodate both mafic and granitoid intrusions and are probably related to an extensional period in the Mesoproterozoic evolution in the western part of the East European Craton. This is a contribution to the project "The Precambrian structure of Baltica as a control of its recent environment and evolution" of the Visby Programme supported by the Swedish Institute and the Lithuanian State Science and Studies Foundation.

  15. Neotectonic deformation versus climate control in the Central Andes of Argentina, insights from 10Be Surface Exposure Dating

    NASA Astrophysics Data System (ADS)

    Terrizzano, Carla; Zech, Roland; Garcia Morabito, Ezequiel; Yamin, Marcela; Haghipour, Negar; Wüthrich, Lorenz; Christl, Marcus

    2015-04-01

    Mountainous regions and their forelands commonly supports a suite of landforms sensitive to climate change and tectonics, providing -if addressed with appropriate geomorphological and geochronological approaches- record for landscape, climate, and tectonic evolution. In particular, alluvial fans are valuable archives of Quaternary climate and tectonics. The southern Central Andes and their forelands provide a perfect setting to study such forcings, since first, the extreme aridity favors the geomorphological preservation of the fan surfaces, so that 10Be surface exposure dating can be applied to establish robust and precise chronologies. And second, the neotectonic activity in this region results in widespread deformation of Quaternary deposits and recent devastating earthquakes. However, rates of uplift and shortening on the reverse faults remain largely unknown and very little is known yet about the Pleistocene climate history in the southern Central Andes, which limits a robust evaluation of the role of climate for the alluvial fan formation and landscape evolution. We combined structural and geomorphic investigations with 10Be surface exposure dating in the western Precordillera of the Southern Central Andes of Argentina (31°30'-31°53' SL/69°20' WL) in order to establish a numeric chronology for four deformed alluvial fan surfaces, to estimate uplift rates and to evaluate the potential climate role in controlling the fan construction and evolution. Surface exposure ages were determined for a few large boulders, amalgamated pebbles, and via depth profiles on sand samples. Boulder ages range from 145 to 212 ka for the oldest well-preserved fan remnants (Q1a, n=3), from 63 to 108 ka (Q2, n=3) and 21-28 ka (Q3, n=2), amalgamated pebbles yield ages range from 106 to 127 ka for the oldest fan surface (Q1b, n=79), all calculations assuming no erosion and using the scaling scheme for spallation based on Lal 1991, Stone 2000. Boulders from current channels have 10Be

  16. Dating the West-Central Pyrenean deformation Front with magnetostratigraphy of its Oligo-Miocene syntectonic deposits

    NASA Astrophysics Data System (ADS)

    Oliva-Urcia, Belén; Beamud, Elisabet; Garcés, Miguel; Soto, Ruth; Pueyo, Emilio; Arenas, Concha

    2014-05-01

    Well-dated foreland basin deposits are crucial to correctly decipher the tectonic evolution of the orogen associated to the foreland basin. A magnetostratigraphic section of ca. 3.200 m in length has been done in the Northern margin of the Ebro foreland Basin, to the South of the frontal thrust (SFT). In this area, the frontal thrust produces the detachment of the Santo Domingo anticline, located in the External Sierras of the West-Central Pyrenees. The main goal of our study is to constrain the age of the upper part of the syntectonic Campodarbe Fm. (Oligo-Miocene) which is at present under discussion and which represents an utterly change in the paleogeography of the depositional systems represented by the replacement of the Campodarbe Fm with the Uncastillo Fm (i.e., general change from overall W-NW-flowing to S-flowing paleocurrents), linked to the late tectonic activity of the SFT with the final tightening of the Santo Domingo anticlinal (Chattian-Aquitanian). Prior to this final tectonic activity and tightening of the anticlinal, overall fluvial paleocurrents (Campodarbe Fm.) were from the S-SE; in contrast, during and after such deformation period, overall southward-flowing alluvial systems occurred. Integration of our new data with previous magnetostratigraphic data of the Uncastillo Fm. and with the careful notation of the dip of layers provides information about the timing of thrusts development and allows reconstructing the kinematics of the Santo Domingo anticline at the western termination of the External Sierrras. The new results indicate that the syn-tectonic deposits of the upper Campodarbe Fm. span over 6.5 Myr and that the upper part of the Campodarbe Fm. is younger than previously considered (reaching chron 7r, in contrast to previous correlations to C10r). On one hand, the new data constrain the cause of the cartographic scale unconformity within the Campodarbe Fm. and sets the time-span of the San Felices thrust sheet activity, part of the

  17. Dating low-temperature deformation by 40Ar/39Ar on white mica, insights from the Argentera-Mercantour Massif (SW Alps)

    NASA Astrophysics Data System (ADS)

    Sanchez, Guillaume; Rolland, Yann; Schneider, Julie; Corsini, Michel; Oliot, Emilien; Goncalves, Philippe; Verati, Chrystèle; Lardeaux, Jean-Marc; Marquer, Didier

    2011-07-01

    In order to date low-temperature deformation, intensely strained muscovite porphyroclasts and neocrystallized shear band phengite from greenschist-facies shear zones have been dated by 40Ar/39Ar method in the Argentera-Mercantour massif. Shear zones are featured by gradual mylonitization of a Variscan granite, gneiss and Permian pelite protolith (300-315 Ma) during the Alpine orogenic event. Mineralogical and textural observations indicate that phengites and chlorites developed from biotite and plagioclase in fluid system during deformation following dissolution-transport-precipitation reactions of the type biotite + plagioclase + aqueous fluid = chlorite + albite + phengite + quartz + titanite + K-bearing fluid in the granite-gneiss mylonite. Contrariwise, phengite developed at the expense of clays following substitution reaction in pelite mylonite. Based on conventional thermobarometry on phengite and chlorite and Pressure-Temperature-aqueous fluid (P-T-MH2O) pseudosections calculated with shear zone bulk compositions, the conditions during shear deformation were estimated at 375 ± 30 °C and 4.8-7 ± 1 kbar in an H2O-satured system. In this low temperature environment, 40Ar/39Ar analysis of the Variscan muscovite for various grades of ductile strain intensity shows a limited 40Ar/39Ar isotopic resetting, all ages scattering between 296 and 315 Ma. Under conditions of intense ductile deformation and large-scale fluid circulation, muscovite grains formed during the Variscan retain their much older ages. 40Ar/39Ar dating of very fine grained synkinematic phengite grains, neoformed during the Alpine history, give consistent plateau ages (34-20 Ma) for each shear zone. In detail, 40Ar excess can be detected in the pelite mylonitic sample where phengites crystallized by substitution process while the other mylonitic samples where phengites grow from fluid-induced reactions do not evidence any 40Ar excess. These results demonstrate that the 40Ar/39Ar dating of

  18. Timing of Deformation in the Central Metasedimentary Belt Boundary Thrust Zone (CMBbtz), southern Ontario, Canada, from Electron Microprobe Dating of Monazite

    NASA Astrophysics Data System (ADS)

    Markley, M. J.; Dunn, S. R.; Peck, W. H.; Jercinovic, M. J.; Williams, M. L.

    2015-12-01

    In the Grenville Province of Southern Ontario, the Central Metasedimentary Belt boundary thrust zone (CMBbtz) is a crustal-scale tectonic boundary between the older, granulite-facies Central Gneiss Belt to the NW and the younger, amphibolite-facies Central Metasedimentary Belt to the SE. Although there are a range of tectonic models for the CMBbtz, most workers agree it is a major tectonic boundary that accommodated ductile thrusting and crustal shortening during the Ottawan phase of the Grenville Orogeny (~1080-1020 Ma). Some studies suggest that ductile thrusting in the CMBbtz was roughly synchronous with synorogenic extensional collapse below an orogenic lid. Previous geochronological studies also provide evidence of earlier deformation and/or metamorphic events in the CMBbtz, although the relation between deformation in the CMBbtz to the Elzeviran (~1230 Ma) and Shawinigan (~1180 Ma) orogenies is unclear. Our study is the first to report in situ electron microprobe monazite (mnz) dates from amphibolite-grade ortho- and para-gneisses of the CMBbtz. Our results are broadly consistent with other chronometers. We present dates from 132 age-domains within 83 mnz grains in 14 samples. Although our data provide strong evidence for deformation and metamorphism along the length of the CMBbtz during the Ottawan (1080-1020 Ma), we also report two other clusters of ages: 1140-1110 Ma and 1230-1170 Ma. The latter cluster falls between the widely accepted ranges for the Elzeviran and Shawinigan orogenies. In addition, some individual outcrops, particularly those in Killaloe and Minden, show mnz ages spanning over 200 m.y., and the setting and compositions of individual monazite domains allow us to link mnz growth to episodes of garnet growth during multiple events. Together these data indicate an unexpectedly continuous and long-lived period of deformation and metamorphism in the CMBbtz.

  19. Application of Lu-Hf garnet dating to unravel the relationships between deformation, metamorphism and plutonism: An example from the Prince Rupert area, British Columbia

    NASA Astrophysics Data System (ADS)

    Wolf, David E.; Andronicos, Christopher L.; Vervoort, Jeffery D.; Mansfield, Michael R.; Chardon, Dominique

    2010-04-01

    The tectonic history of the Prince Rupert area is marked by profound crustal thickening from thrusting that produced inverted metamorphic field gradients and transpression in crustal-scale shear zones. Syn-tectonic garnet in the Prince Rupert area has Lu-Hf ages of 102.6 ± 3.7 Ma and 108.3 ± 4.1 Ma (2 σ). Porphyroblast-matrix relationships in these samples, and samples from the same outcrops, indicate syn-tectonic garnet growth. These relationships imply that the garnet ages directly date the development of the metamorphic foliations. A third sample of migmatitic garnet amphibolite from the contact aureole of the 94-90 Ma Ecstall pluton had complex isotope systematics interpreted to indicate a garnet growth episode ˜ 105 Ma, similar to the ages obtained from the other samples and a growth or equilibration event at ˜ 94 Ma during pluton emplacement. The data show that the older Lu-Hf garnet ages date prograde metamorphism during foliation development and modification during pluton emplacement. The Ecstall pluton was emplaced 10 to 15 m.y. after regional metamorphism and thrust stacking in the Prince Rupert area. In order to place our samples in a regional tectonic context we compare our results to patterns of regional deformation, metamorphism and plutonism throughout the North American Cordillera in the time period between 110 and 85 Ma. Contractional and transpressional deformation occurred throughout much of the North American Cordillera at this time, from southeastern Alaska to the Baja Peninsula in Mexico. Left-lateral transpression dominated the Canadian Cordillera, whereas, right-lateral transpression affected areas south of the Idaho-Salmon River suture zone, including the Sierra Nevada batholith. This reversal in kinematics in the northern and southern cordillera within coeval magmatic belts appears to be a first-order feature of the geology of the North American Cordillera during the Cretaceous.

  20. Upper crustal emplacement and deformation of granitoids inside the Uppermost Unit of the Cretan nappe stack: constraints from U-Pb zircon dating, microfabrics and paleostress analyses

    NASA Astrophysics Data System (ADS)

    Kneuker, Tilo; Dörr, Wolfgang; Petschick, Rainer; Zulauf, Gernold

    2015-03-01

    The present study is dealing with the emplacement and deformation of diorite and quartz diorite exposed along new road cuts between Agios Nikolaos and Sitia (Uppermost Unit, eastern Crete). Mingling of both melt types is indicated by enclaves of diorite inside quartz diorite and vice versa. The diorite and quartz diorite intruded into coarse-grained white marble, which is in lateral contact to, but also forms the roof of, the intrusive body. Evidence for contact metamorphism is indicated by increasing grain size of calcite in the marble with decreasing distance from the diorite. U-Pb (TIMS) dating of zircons, separated from quartz diorite, yielded a concordant age at 74.0 ± 0.25 Ma, which is interpreted as emplacement age. As this age is close to published K-Ar cooling ages of hornblende and biotite, the melt should have intruded and cooled down rapidly at upper structural levels, which is not common for granitoids of the Uppermost Unit of Crete. Upper crustal melt emplacement is also documented by stoped blocks and by the lack of any ductile (viscous) deformation. The diorite and quartz diorite, however, are affected by strong post-Oligocene brittle faulting. Paleostress analysis, based on these faults, revealed a change in stress field from N-S and NNW-SSE shortening by thrusting (convergence between African and European plates) to NNE-SSW and NE-SW shortening accommodated by strike-slip (SW-ward extrusion of the Anatolian microplate). Calcite-twin density indicates high differential stress (260 ± 20 MPa) related to these phases of crustal shortening.

  1. Age dating of mineralization and brittle deformation using rhenium-osmium (Re-Os) geochronology in pyrite-bitumen bearing fracture systems

    NASA Astrophysics Data System (ADS)

    Holdsworth, Robert; Dempsey, Eddie; Selby, David; Dichiarante, Anna; Finlay, Alex; Ogilvie, Steven

    2013-04-01

    The relative ages of different fault rocks are generally established using cross-cutting relationships seen in the field and thin section. However, the absolute dating of fault rock formation events remains a problematic issue. In many Phanerozoic basins, hydrocarbon (mainly bitumen)-bearing fault and fracture systems also carry sulphide minerals such as pyrite. The bitumen and pyrite are commonly enriched with rhenium (Re) so that the 187Re-187Os geochronometer can be used to date mineralization and better constrain the timing of brittle deformation. Furthermore, the determined 187Os/188Os composition of the sulphide minerals at the time of formation can yield insights into the origins of the fracture-hosted fluids. We report 3 cases of Re-Os sulphide geochronology from fracture-hosted hydrocarbon-pyrite systems offshore West of Shetland (UK) and in the nearby onshore Orcadian Basin, N Scotland. Hydrocarbon Re-Os data from the Faroe-Shetland Basin (FSB) show that there are four pulses of increased oil generation at 72 ± 5 Ma, 64 ± 4 Ma, 53 ± 14 Ma and 42 ± 6 Ma. These dates remove the need for large scale oil collection within fractured basement and Late Cretaceous reservoirs before re-migration into later Cenozoic reservoirs and agree with more recent models in which oil generation has been retarded by over pressure and that multiple pulses of generation are associated with regional inversion events that occurred during the Late Cretaceous, Paleocene and Oligocene/Miocene. The Clair oil field lies on the SE side of the FSB and a major part of the reservoir lies in Lewisian basement where hosting fractures are infilled with pyrite, calcite and bitumen. The pyrite contains low abundances of Re and Os, with Re-Os isotope compositions that are too similar to yield an isochron, whilst the associated bitumen is enriched in both Re and Os. Regression of the Re-Os data from other parts of the Clair field with the new pyrite Re-Os data obtained here yields a more

  2. Lunar and Planetary Science XXXV: Impact-Related Deposits

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The session "Impact-Related Deposits" included:Evidence for a Lightning-Strike Origin of the Edeowie Glass; 57Fe M ssbauer Spectroscopy of Fulgurites: Implications for Chemical Reduction; Ca-Metasomatism in Crystalline Target Rocks from the Charlevoix Structure, Quebec, Canada: Evidence for Impact-related Hydrothermal Activity; Magnetic Investigations of Breccia Veins and Basement Rocks from Roter Kamm Crater and Surrounding Region, Namibia; Petrologic Complexities of the Manicouagan Melt Sheet: Implications for 40Ar-39Ar Geochronology; Laser Argon Dating of Melt Breccias from the Siljan Impact Structure, Sweden: Implications for Possible Relationship to Late Devonian Extinction Events; Lunar Impact Crater, India: Occurrence of a Basaltic Suevite?; Age of the Lunar Impact Crater, India: First Results from Fission Track Dating; The Fluidized Chicxulub Ejecta Blanket, Mexico: Implications for Mars; Low Velocity Ejection of Boulders from Small Lunar Craters: Ground Truth for Asteroid Surfaces; Ejecta and Secondary Crater Distributions of Tycho Crater: Effects of an Oblique Impact; Potassium Isotope Systematics of Crystalline Lunar Spherules from Apollo 16; Late Paleocene Spherules from the North Sea: Probable Sea Floor Precipitates: A Silverpit Provenance Unproven; A Lithological Investigation of Marine Strata from the Triassic-Jurassic Boundary Interval, Queen Charlotte Islands, British Columbia, Including a Search for Shocked Quartz; Triassic Cratered Cobbles: Shock Effects or Tectonic Pressure?; Regional Variations of Trace Element Composition Within the Australasian Tektite Strewn Field; Cretaceous-Tertiary Boundary Microtektite-bearing Sands and Tsunami Beds, Alabama Gulf Coastal Plain; Sand Lobes on Stewart Island as Probable Impact-Tsunami Deposits; Distal Impact Ejecta, Uppermost Eocene, Texas Coastal Plain; and Continental Impact Debris in the Eltanin Impact Layer.

  3. Quaternary deformation

    SciTech Connect

    Brown, R.D. Jr.

    1990-01-01

    Displaced or deformed rock units and landforms record the past 2 m.y. of faulting, folding, uplift, and subsidence in California. Properly interpreted, such evidence provides a quantitative basis for predicting future earthquake activity and for relating many diverse structures and landforms to the 5 cm/yr of horizontal motion at the boundary between the North American and Pacific plates. Modern techniques of geologic dating and expanded research on earthquake hazards have greatly improved our knowledge of the San Andreas fault system. Much of this new knowledge has been gained since 1965, and that part which concerns crustal deformation during the past 2 m.y. is briefly summarized here.

  4. Analysis, comparison, and modeling of radar interferometry, date of surface deformation signals associated with underground explosions, mine collapses and earthquakes. Phase I: underground explosions, Nevada Test Site

    SciTech Connect

    Foxall, W; Vincent, P; Walter, W

    1999-07-23

    We have previously presented simple elastic deformation modeling results for three classes of seismic events of concern in monitoring the CTBT--underground explosions, mine collapses and earthquakes. Those results explored the theoretical detectability of each event type using synthetic aperture radar interferometry (InSAR) based on commercially available satellite data. In those studies we identified and compared the characteristics of synthetic interferograms that distinguish each event type, as well the ability of the interferograms to constrain source parameters. These idealized modeling results, together with preliminary analysis of InSAR data for the 1995 mb 5.2 Solvay mine collapse in southwestern Wyoming, suggested that InSAR data used in conjunction with regional seismic monitoring holds great potential for CTBT discrimination and seismic source analysis, as well as providing accurate ground truth parameters for regional calibration events. In this paper we further examine the detectability and ''discriminating'' power of InSAR by presenting results from InSAR data processing, analysis and modeling of the surface deformation signals associated with underground explosions. Specifically, we present results of a detailed study of coseismic and postseismic surface deformation signals associated with underground nuclear and chemical explosion tests at the Nevada Test Site (NTS). Several interferograms were formed from raw ERS-1/2 radar data covering different time spans and epochs beginning just prior to the last U.S. nuclear tests in 1992 and ending in 1996. These interferograms have yielded information about the nature and duration of the source processes that produced the surface deformations associated with these events. A critical result of this study is that significant post-event surface deformation associated with underground nuclear explosions detonated at depths in excess of 600 meters can be detected using differential radar interferometry. An

  5. An up-to-date GNSS velocity field of the Upper Rhine Graben: an active seismic region without observed present deformations?

    NASA Astrophysics Data System (ADS)

    Masson, Frédéric; Henrion, Eric; Ulrich, Patrice

    2016-04-01

    The Rhine Graben is the central, most prominent segment of the European Cenozoic rift system (ECRIS) of Oligocene age, which extends from the North Sea through Germany and France to the Mediterranean coast over a distance of some 1000 km. Within GURN the focus will be on the Upper Rhine Graben (URG). The URG is a 300 km long and 40 km wide SSW-NNE trending rift, extending from Basel (Switzerland) to Frankfurt (Germany). It is limited to the west by the Vosges mountains and to the east by the Black Forest. The graben is bounded to the north by the uplifted area of the Rhenish Massif. To the south, the Leymen, Ferrette and Vendlincourt folds represent the northern-most structural front of the Jura fold and thrust belt. In this study, we will present an up-to-date GNSS velocity field of the area based on a network of about 70 stations older than 5 years and ranging up to 12 years. The processing of the final velocity field go through some of corrections due to the use of a permanent GNSS network. An antenna switch generally induce a jump in the data which we have to correct. We also have to correct the outliers in the time series. The last step is to analyze the quality of the series based on the support and environment of the site, if the series is too biased by a flicker noise, we decide to reject it. The results seem to clearly indicate the lack of consistent horizontal velocities (on average 0.38mm/yr) in the URG, which could be not true fort vertical velocities.

  6. Deformable Nanolaminate Optics

    SciTech Connect

    Olivier, S S; Papavasiliou, A P; Barbee, T W; Miles, R R; Walton, C C; Cohn, M B; Chang, K

    2006-05-12

    We are developing a new class of deformable optic based on electrostatic actuation of nanolaminate foils. These foils are engineered at the atomic level to provide optimal opto-mechanical properties, including surface quality, strength and stiffness, for a wide range of deformable optics. We are combining these foils, developed at Lawrence Livermore National Laboratory (LLNL), with commercial metal processing techniques to produce prototype deformable optics with aperture sizes up to 10 cm and actuator spacing from 1 mm to 1 cm and with a range of surface deformation designed to be as much as 10 microns. The existing capability for producing nanolaminate foils at LLNL, coupled with the commercial metal processing techniques being used, enable the potential production of these deformable optics with aperture sizes of over 1 m, and much larger deformable optics could potentially be produced by tiling multiple deformable segments. In addition, based on the fabrication processes being used, deformable nanolaminate optics could potentially be produced with areal densities of less than 1 kg per square m for applications in which lightweight deformable optics are desirable, and deformable nanolaminate optics could potentially be fabricated with intrinsically curved surfaces, including aspheric shapes. We will describe the basic principles of these devices, and we will present details of the design, fabrication and characterization of the prototype deformable nanolaminate optics that have been developed to date. We will also discuss the possibilities for future work on scaling these devices to larger sizes and developing both devices with lower areal densities and devices with curved surfaces.

  7. Dating Violence

    MedlinePlus

    ... Parents of Teens Crime, Teens, and Trauma Assault Bullying and Harassment Child Sexual Abuse Dating Violence Sexual ... Parents of Teens Crime, Teens, and Trauma Assault Bullying and Harassment Child Sexual Abuse Dating Violence Sexual ...

  8. Radiocarbon Dating

    SciTech Connect

    Buchholz, B A

    2007-12-20

    Radiocarbon dating can be used to determine the age of objects that contain components that were once alive. In the case of human remains, a radiocarbon date can distinguish between a crime scene and an archeological site. Documents, museum artifacts and art objects can be dated to determine if their age is correct for the historical context. A radiocarbon date does not confirm authenticity, but it can help identify a forgery.

  9. DATE PALM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book chapter reviews date palm biology and cultivation. Date palm (Phoenix dactylifera L.) is one of the oldest fruit crops grown in the arid regions of the Arabian Peninsula, North Africa, and the Middle East. The exact origin of the date palm is unknown but most probably the area of origin w...

  10. Dating Violence

    ERIC Educational Resources Information Center

    Stader, David L.

    2011-01-01

    Dating violence is a form of student-on-student victimization and is a serious school safety issue. Research indicates that at a minimum, 10 percent of high school students are victims of dating violence in one form or another. Among female high school students that date, some data indicate that as many as 30 percent may be victims of dating…

  11. Radiocarbon Dating.

    PubMed

    Van Strydonck, Mark

    2016-04-01

    Although most historians and art historians consider the radiocarbon dating technique not to be very precise by their criteria, the method has gained much importance over the last decades. Radiocarbon dating is increasingly used in the field of textile research and old polychrome statues, but also objects made of ivory, stucco, paper, and parchment are dated with the technique. Especially after the introduction of the AMS technique, a boom of this type of research has been noticed. PMID:27573138

  12. Dating Violence

    MedlinePlus

    ... Dating violence can cause serious harm to your body and your emotions. If you are in an abusive relationship, get help. Leaving an abusive dating relationship See a doctor or nurse to take care of any physical problems. And reach out for support for your emotional ...

  13. Haglund's Deformity

    MedlinePlus

    ... Is Haglund’s Deformity? Haglund’s deformity is a bony enlargement on the back of the heel. The soft ... the Achilles tendon becomes irritated when the bony enlargement rubs against shoes. This often leads to painful ...

  14. Madelung Deformity.

    PubMed

    Kozin, Scott H; Zlotolow, Dan A

    2015-10-01

    Madelung deformity of the wrist is more common in females and is often associated with Leri Weill dyschondrosteosis, a mesomelic form of dwarfism. Patients with Madelung deformity often report wrist deformity resulting from the prominence of the relatively long ulna. The typical Madelung deformity is associated with a Vickers ligament that creates a tether across the volar-ulnar radial physis that restricts growth across this segment. The distal radius deforms in the coronal (increasing radial inclination) and the sagittal (increasing volar tilt) planes. There is lunate subsidence and the proximal carpal row adapts to the deformity by forming an upside-down pyramid shape or triangle. Treatment depends on the age at presentation, degree of deformity, and magnitude of symptoms. Mild asymptomatic deformity warrants a period of nonsurgical management with serial x-ray examinations because the natural history is unpredictable. Many patients never require surgical intervention. Progressive deformity in the young child with considerable growth potential remaining requires release of Vickers ligament and radial physiolysis to prevent ongoing deterioration Concomitant ulnar epiphysiodesis may be necessary. Advanced asymptomatic deformity in older children with an unacceptable-appearing wrist or symptomatic deformity are indications for surgery. A dome osteotomy of the radius allows 3-dimensional correction of the deformity. Positive radiographic and clinical results after dome osteotomy have been reported. PMID:26341718

  15. Spinal deformity.

    PubMed

    Bunnell, W P

    1986-12-01

    Spinal deformity is a relatively common disorder, particularly in teenage girls. Early detection is possible by a simple, quick visual inspection that should be a standard part of the routine examination of all preteen and teenage patients. Follow-up observation will reveal those curvatures that are progressive and permit orthotic treatment to prevent further increase in the deformity. Spinal fusion offers correction and stabilization of more severe degrees of scoliosis. PMID:3786010

  16. Madelung deformity.

    PubMed

    Ghatan, Andrew C; Hanel, Douglas P

    2013-06-01

    Madelung deformity is a rare congenital anomaly of the wrist caused by asymmetric growth at the distal radial physis secondary to a partial ulnar-sided arrest. The deformity is characterized by ulnar and palmar curvature of the distal radius, positive ulnar variance, and proximal subsidence of the lunate. It more commonly occurs in females than males and typically affects both wrists. The deformity can occur in isolation or as part of a genetic syndrome. The pattern of inheritance varies, with some cases following a pseudoautosomal pattern and many others lacking a clear family history. Nonsurgical management is typically advocated in asymptomatic patients. Few studies exist on the natural history of the condition; however, extensor tendon ruptures have been reported in severe and chronic cases. Stiffness, pain, and patient concerns regarding wrist cosmesis have been cited as indications for surgery. Various techniques for surgical management of Madelung deformity have been described, but clear evidence to support the use of any single approach is lacking. PMID:23728962

  17. Dating tectonic structures on Mercury

    NASA Astrophysics Data System (ADS)

    Giacomini, L.; Massironi, M.; Marchi, S.; Cremonese, G.

    2012-09-01

    Mercury surface appears to be interested by several tectonic structures, the most interesting ones being numerous lobate scarps formed mainly thanks to planet cooling and contraction. The Messenger cameras (MDIS WAC and NAC) allowed us to map several structures not previously detected. Among these a 250 km-long thrust has been detected crossing a peak ring basin. The region encircled within the inner ring of the basin is covered by a smooth plain with evidence of a sin-deformational emplacement. Dating this smooth plain with crater counting technique allowed us to give an age constrain of the tectonic structure.

  18. Teen Dating Violence

    MedlinePlus

    ... dating violence prevention initiative seeks to reduce dating violence and increase healthy relationships in high-risk urban communities through comprehensive, multisector prevention. Division of Adolescent ...

  19. Dating and Marriage

    MedlinePlus

    ... Family : Dating & Marriage Subscribe Translate Text Size Print Dating and Marriage Dating and Marriage If you are living with HIV, ... Living! Having HIV does not prevent you from dating or marrying—it just may require a little ...

  20. Food Product Dating

    MedlinePlus

    ... Formula What do can codes mean? Dates on Egg Cartons UPC or Bar Codes Storage Times Refrigerator ... primarily on perishable foods such as meat, poultry, eggs and dairy products. "Closed" or "coded" dating might ...

  1. A Date with Violence.

    ERIC Educational Resources Information Center

    Lowe, Robert; And Others

    1997-01-01

    Teen dating violence is common but preventable. A survey of Texas high schoolers showed that half of respondents had been victims of dating violence. A majority of both sexes believed that certain behaviors justified being hit by their dating partners. It is important to raise the awareness of school personnel, parents, and students. Peer…

  2. Radiometric Dating Does Work!

    ERIC Educational Resources Information Center

    Dalrymple, G. Brent

    2000-01-01

    Discusses the accuracy of dating methods and creationist arguments that radiometric dating does not work. Explains the Manson meteorite impact and the Pierre shale, the ages of meteorites, the K-T tektites, and dating the Mount Vesuvius eruption. (Author/YDS)

  3. 76 FR 28480 - Environmental Assessment and Finding of No Significant Impact Related to Exemption From Certain...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-05-17

    ... From the Federal Register Online via the Government Publishing Office ] NUCLEAR REGULATORY COMMISSION ; Docket No. 50-010 Environmental Assessment and Finding of No Significant Impact Related to Exemption From Certain Requirements for the Dresden Nuclear Power Station, Unit No. 1 License DPR-002, Grundy County, IL AGENCY: Nuclear...

  4. Models of the Dynamic Deformations of Polymers

    NASA Astrophysics Data System (ADS)

    Merzhievsky, Lev; Voronin, Mihail; Korchagina, Anna

    2013-06-01

    In the process of deformation under the influence of external loading polymeric mediums show the complicated behavior connected with features of their structure. For amorphous polymers distinguish three physical conditions - glasslike, highlyelastic and viscoplastic. To each of the listed conditions there corresponds to mikro - meso- and macrostructural mechanisms of irreversible deformation. In the report the review of results of construction of models for the description of dynamic and shock-wave deformation of the polymers which are based on developed authors representations about mechanisms of irreversible deformation is made. Models include the formulation of the equations of conservation laws, considering effect of a relaxation of shear stresses in the process of deformation. For closing of models the equations of states with nonspherical tensor of deformations and relation for time of a relaxation of shear stresses are constructed. With using of the formulated models a number of problems of dynamic and shock wave deformations has been solved. The results are compared with corresponding experimental date. Development of the used approach are in summary discussed. To taking into account memory and fractal properties of real polymers is supposed of derivatives and integrals of a fractional order to use. Examples of constitutive equations with derivatives of a fractional order are presented. This work is supported by the Integration project of the Siberian Branch of the Russian Academy of Science 64 and grant RFBR 12-01-00726.

  5. Chemical Principles Revisited: Archaeological Dating.

    ERIC Educational Resources Information Center

    Rowe, M. W.

    1986-01-01

    Discusses methods used to date archaeological artifacts and other remains. They include: (1) nuclear dating techniques (radiocarbon dating, accelerator radiocarbon dating, thermoluminescence, and others); (2) chemical dating techniques (amino acid racemization, obsidian hydration dating, elemental content changes, and thermal analysis dating); and…

  6. Deformations in VLBI antennas

    NASA Technical Reports Server (NTRS)

    Clark, T. A.; Thomsen, P.

    1988-01-01

    A study is presented of deformations in antennas with the emphasis on their influence on VLBI measurements. The GIFTS structural analysis program has been used to model the VLBI antenna in Fairbanks (Alaska). The report identifies key deformations and studies the effect of gravity, wind, and temperature. Estimates of expected deformations are given.

  7. Dating Violence in Russia

    ERIC Educational Resources Information Center

    Lysova, A. V.

    2007-01-01

    The phenomenon of violence in interpersonal relationships has been little studied in Russia, and the phenomenon of violence between dating partners has not been the object of scientific interest at all. The study on which the present article is based was designed to obtain information about the violence in dating among students enrolled in…

  8. Date Palm Germplasm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This book chapter reviews date palm genetic resources and their conservation. Date palm (Phoenix dactylifera) is an important food crop in the Middle East and North Africa. Its center of origin and diversity most probably is the area near Iraq/Iran. From there, it spread throughout its present range...

  9. Radiometric Dating in Geology.

    ERIC Educational Resources Information Center

    Pankhurst, R. J.

    1980-01-01

    Described are several aspects and methods of quantitatively measuring geologic time using a constant-rate natural process of radioactive decay. Topics include half lives and decay constants, radiogenic growth, potassium-argon dating, rubidium-strontium dating, and the role of geochronology in support of geological exploration. (DS)

  10. Choosing a Calving Date

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Calving date affects cost and timing of production events. Due to the polyestrous nature of beef females, producers can choose a calving date that fits their production system and geographic region. Any time an entire production system is considered, decision making becomes complex. Any calving syst...

  11. Dating tectonic structures on Mercury

    NASA Astrophysics Data System (ADS)

    Giacomini, Lorenza; Massironi, Matteo; Marchi, Simone; Cremonese, Gabriele

    2013-04-01

    Mercury is a planet dominated by contractional features at a global scale, represented mainly by lobate scarps. These structures are the expression of surface-breaking thrust faults and are linear or arcuate features widely distributed on Mercury. Since they display a broad distribution of orientations their origin is hypothesized to be related to a global contraction. By summing of the crustal shortening associated to scarps, a decreasing of the planet radius of about 1-2 km (Strom et al., 1975, JGR, 80, 2478-2507) or more (Di Achille et al., 2012, Icarus, 221, 456-460) was calculated. This process was hypothesized to occur at the edge of the Late Heavy Bombardment (≥3.8 Ga ago) (Strom et al., 1975, JGR, 80, 2478-2507; Watters and Nimmo, 2010, in Planetary tectonics, 15-80). The Messenger cameras (MDIS WAC and NAC), acquired images of new regions of the Mercury surface that allowed us to detect several new lobate scarps especially where the illumination geometry is more favorable for structural analysis (Di Achille et al., 2012, Icarus, 221, 456-460). Among these a 350 km-long thrust has been detected crossing a peak ring basin (about 186 km of diameter), located at 3°87' N and 87°17'E. The region encircled within the inner ring of the basin is covered by a smooth plain with evidence of a sin-deformational emplacement. This allowed us to give an age constrain of the tectonic structure. Indeed our preliminary crater count dates the smooth plain at 3.7-3.6 Ga fixing a straight upper limit to the contractional deformation in this sector of the planet.

  12. Teen Dating Violence.

    ERIC Educational Resources Information Center

    O'Keeffe, Nona K.; And Others

    1986-01-01

    Surveyed high school students (N=256) in Sacramento, California. Found that 35.1 percent had experienced some form of abuse in their dating relationships. Explored the severity of the violence and its intergenerational component. (Author/ABB)

  13. Primate molecular divergence dates.

    PubMed

    Steiper, Michael E; Young, Nathan M

    2006-11-01

    With genomic data, alignments can be assembled that greatly increase the number of informative sites for analysis of molecular divergence dates. Here, we present an estimate of the molecular divergence dates for all of the major primate groups. These date estimates are based on a Bayesian analysis of approximately 59.8 kbp of genomic data from 13 primates and 6 mammalian outgroups, using a range of paleontologically supported calibration estimates. Results support a Cretaceous last common ancestor of extant primates (approximately 77 mya), an Eocene divergence between platyrrhine and catarrhine primates (approximately 43 mya), an Oligocene origin of apes and Old World monkeys (approximately 31 mya), and an early Miocene (approximately 18 mya) divergence of Asian and African great apes. These dates are examined in the context of other molecular clock studies. PMID:16815047

  14. Dating the Vinland Map

    ScienceCinema

    None

    2013-07-17

    Scientists from Brookhaven National Laboratory, the University of Arizona, and the Smithsonian Institution used carbon-dating technology to determine the age of a controversial parchment that might be the first-ever map of North America.

  15. Dating the Vinland Map

    SciTech Connect

    2013-01-04

    Scientists from Brookhaven National Laboratory, the University of Arizona, and the Smithsonian Institution used carbon-dating technology to determine the age of a controversial parchment that might be the first-ever map of North America.

  16. Clinical Implications of Nasal Septal Deformities.

    PubMed

    Mladina, Ranko; Skitarelić, Neven; Poje, Gorazd; Šubarić, Marin

    2015-04-01

    The first attempts to systematize septal distortions have been given by Cottle who defined four groups of septal deformities: subluxation, large spurs, caudal deflection and tension septum. Fortunately, the variations of the septal deformities show a certain order, thus enabling more precise classification. Mladina was the first to make user-friendly classification of septal deformities in six basic types. He also described the seventh type, named "Passali deformity", which presents individually, but is always a well-defined combination between some of the previous six types. Mladina types of septal deformities (SD) are divided in two main groups: so called "vertical" deformities (types 1, 2, 3 and 4), and "horizontal" ones (types 5 and 6). This classification was immediately well accepted by rhinologists worldwide and started to be cited from the very beginning. Since then it has been continuously cited increasingly more often, thus making Mladina classification a gold standard whenever clinical researches on nasal septum are concerned. More than forty clinical studies based on this classification have been performed to date. It is extremely important to make a strict distinction between the types of SD since all of them play some specific role in the nasal and general physiology in man. PMID:26167337

  17. Significance of geometrical relationships between low-temperature intracrystalline deformation microstructures in naturally deformed quartz

    NASA Astrophysics Data System (ADS)

    Derez, T.; Pennock, G.; Drury, M. R.; Sintubin, M.

    2013-12-01

    -temperature intracrystalline deformation microstructures in naturally deformed vein quartz show particular geometrical relationships, in our opinion a to date underexposed aspect of these microstructures. Several of these geometrical relationships will be presented and their potential implications with respect to deformation mechanisms and conditions will be discussed. The geometrical relationships observed may suggest a similar formation mechanism for the different microstructures, a weakening effect for successive microstructure formation and a strong dependency on the crystallographic orientation.

  18. Deformable bearing seat

    NASA Technical Reports Server (NTRS)

    Moreman, O. S., III (Inventor)

    1977-01-01

    A deformable bearing seat is described for seating a bearing assembly in a housing. The seat includes a seating surface in the housing having a first predetermined spheroidal contour when the housing is in an undeformed mode. The seating surface is deformable to a second predetermined spherically contoured surface when the housing is in a deformed mode. The seat is particularly adaptable for application to a rotating blade and mounting ring assembly in a gas turbine engine.

  19. Deformed discrete symmetries

    NASA Astrophysics Data System (ADS)

    Arzano, Michele; Kowalski-Glikman, Jerzy

    2016-09-01

    We construct discrete symmetry transformations for deformed relativistic kinematics based on group valued momenta. We focus on the specific example of κ-deformations of the Poincaré algebra with associated momenta living on (a sub-manifold of) de Sitter space. Our approach relies on the description of quantum states constructed from deformed kinematics and the observable charges associated with them. The results we present provide the first step towards the analysis of experimental bounds on the deformation parameter κ to be derived via precision measurements of discrete symmetries and CPT.

  20. Fluctuations as stochastic deformation.

    PubMed

    Kazinski, P O

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium. PMID:18517590

  1. Fluctuations as stochastic deformation

    NASA Astrophysics Data System (ADS)

    Kazinski, P. O.

    2008-04-01

    A notion of stochastic deformation is introduced and the corresponding algebraic deformation procedure is developed. This procedure is analogous to the deformation of an algebra of observables like deformation quantization, but for an imaginary deformation parameter (the Planck constant). This method is demonstrated on diverse relativistic and nonrelativistic models with finite and infinite degrees of freedom. It is shown that under stochastic deformation the model of a nonrelativistic particle interacting with the electromagnetic field on a curved background passes into the stochastic model described by the Fokker-Planck equation with the diffusion tensor being the inverse metric tensor. The first stochastic correction to the Newton equations for this system is found. The Klein-Kramers equation is also derived as the stochastic deformation of a certain classical model. Relativistic generalizations of the Fokker-Planck and Klein-Kramers equations are obtained by applying the procedure of stochastic deformation to appropriate relativistic classical models. The analog of the Fokker-Planck equation associated with the stochastic Lorentz-Dirac equation is derived too. The stochastic deformation of the models of a free scalar field and an electromagnetic field is investigated. It turns out that in the latter case the obtained stochastic model describes a fluctuating electromagnetic field in a transparent medium.

  2. Radiocarbon Dating the Anthropocene

    NASA Astrophysics Data System (ADS)

    Chaput, M. A.; Gajewski, K. J.

    2015-12-01

    The Anthropocene has no agreed start date since current suggestions for its beginning range from Pre-Industrial times to the Industrial Revolution, and from the mid-twentieth century to the future. To set the boundary of the Anthropocene in geological time, we must first understand when, how and to what extent humans began altering the Earth system. One aspect of this involves reconstructing the effects of prehistoric human activity on the physical landscape. However, for global reconstructions of land use and land cover change to be more accurately interpreted in the context of human interaction with the landscape, large-scale spatio-temporal demographic changes in prehistoric populations must be known. Estimates of the relative number of prehistoric humans in different regions of the world and at different moments in time are needed. To this end, we analyze a dataset of radiocarbon dates from the Canadian Archaeological Radiocarbon Database (CARD), the Palaeolithic Database of Europe and the AustArch Database of Australia, as well as published dates from South America. This is the first time such a large quantity of dates (approximately 60,000) has been mapped and studied at a global scale. Initial results from the analysis of temporal frequency distributions of calibrated radiocarbon dates, assumed to be proportional to population density, will be discussed. The utility of radiocarbon dates in studies of the Anthropocene will be evaluated and potential links between population density and changes in atmospheric greenhouse gas concentrations, climate, migration patterning and fire frequency coincidence will be considered.

  3. Plutonium age dating reloaded

    NASA Astrophysics Data System (ADS)

    Sturm, Monika; Richter, Stephan; Aregbe, Yetunde; Wellum, Roger; Mayer, Klaus; Prohaska, Thomas

    2014-05-01

    Although the age determination of plutonium is and has been a pillar of nuclear forensic investigations for many years, additional research in the field of plutonium age dating is still needed and leads to new insights as the present work shows: Plutonium is commonly dated with the help of the 241Pu/241Am chronometer using gamma spectrometry; in fewer cases the 240Pu/236U chronometer has been used. The age dating results of the 239Pu/235U chronometer and the 238Pu/234U chronometer are scarcely applied in addition to the 240Pu/236U chronometer, although their results can be obtained simultaneously from the same mass spectrometric experiments as the age dating result of latter. The reliability of the result can be tested when the results of different chronometers are compared. The 242Pu/238U chronometer is normally not evaluated at all due to its sensitivity to contamination with natural uranium. This apparent 'weakness' that renders the age dating results of the 242Pu/238U chronometer almost useless for nuclear forensic investigations, however turns out to be an advantage looked at from another perspective: the 242Pu/238U chronometer can be utilized as an indicator for uranium contamination of plutonium samples and even help to identify the nature of this contamination. To illustrate this the age dating results of all four Pu/U clocks mentioned above are discussed for one plutonium sample (NBS 946) that shows no signs of uranium contamination and for three additional plutonium samples. In case the 242Pu/238U chronometer results in an older 'age' than the other Pu/U chronometers, contamination with either a small amount of enriched or with natural or depleted uranium is for example possible. If the age dating result of the 239Pu/235U chronometer is also influenced the nature of the contamination can be identified; enriched uranium is in this latter case a likely cause for the missmatch of the age dating results of the Pu/U chronometers.

  4. The Realities of Date Rape.

    ERIC Educational Resources Information Center

    Presley, Cara; Watson, Jennifer; Williams, Audrey R.

    This poster presentation addresses the issue of date rape, specifically in the college environment. Highlighted are date rape statistics, demographics, and date rape drugs. Also discussed are date rape warnings and prevention strategies. It is concluded that college and university administrators must place the issue of date rape and acquaintance…

  5. Resurgent deformation quantisation

    SciTech Connect

    Garay, Mauricio; Goursac, Axel de; Straten, Duco van

    2014-03-15

    We construct a version of the complex Heisenberg algebra based on the idea of endless analytic continuation. The algebra would be large enough to capture quantum effects that escape ordinary formal deformation quantisation. -- Highlights: •We construct resurgent deformation quantisation. •We give integral formulæ. •We compute examples which show that hypergeometric functions appear naturally in quantum computations.

  6. Deformation mechanisms in experimentally deformed Boom Clay

    NASA Astrophysics Data System (ADS)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

    Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures

  7. The Dating Game.

    ERIC Educational Resources Information Center

    Zerger, Monte J.

    1998-01-01

    Presents activities to cultivate the tendency to see special qualities in numbers that can be played on certain calendar days. Includes games on the constant of the day, Fibonacci and golden ratio dates, primes, powers, December 25, and the day of the year. (ASK)

  8. Biodiversity of date palm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The date palm (Phoenix dactylifera) is the dominant component upon which the sustainable biophysical and socio-economic structures of the oasis ecosystem are based; a fruit tree with unique nutritional, biochemical and biophysical characteristics, a rich source of aesthetic and cultural values, and ...

  9. Allowable CO2 emissions based on regional and impact-related climate targets.

    PubMed

    Seneviratne, Sonia I; Donat, Markus G; Pitman, Andy J; Knutti, Reto; Wilby, Robert L

    2016-01-28

    Global temperature targets, such as the widely accepted limit of an increase above pre-industrial temperatures of two degrees Celsius, may fail to communicate the urgency of reducing carbon dioxide (CO2) emissions. The translation of CO2 emissions into regional- and impact-related climate targets could be more powerful because such targets are more directly aligned with individual national interests. We illustrate this approach using regional changes in extreme temperatures and precipitation. These scale robustly with global temperature across scenarios, and thus with cumulative CO2 emissions. This is particularly relevant for changes in regional extreme temperatures on land, which are much greater than changes in the associated global mean. PMID:26789252

  10. Deformable human body model development

    SciTech Connect

    Wray, W.O.; Aida, T.

    1998-11-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). A Deformable Human Body Model (DHBM) capable of simulating a wide variety of deformation interactions between man and his environment has been developed. The model was intended to have applications in automobile safety analysis, soldier survivability studies and assistive technology development for the disabled. To date, we have demonstrated the utility of the DHBM in automobile safety analysis and are currently engaged in discussions with the U.S. military involving two additional applications. More specifically, the DHBM has been incorporated into a Virtual Safety Lab (VSL) for automobile design under contract to General Motors Corporation. Furthermore, we have won $1.8M in funding from the U.S. Army Medical Research and Material Command for development of a noninvasive intracranial pressure measurement system. The proposed research makes use of the detailed head model that is a component of the DHBM; the project duration is three years. In addition, we have been contacted by the Air Force Armstrong Aerospace Medical Research Laboratory concerning possible use of the DHBM in analyzing the loads and injury potential to pilots upon ejection from military aircraft. Current discussions with Armstrong involve possible LANL participation in a comparison between DHBM and the Air Force Articulated Total Body (ATB) model that is the current military standard.

  11. Clinical Implications of Nasal Septal Deformities

    PubMed Central

    Mladina, Ranko; Skitarelić, Neven; Poje, Gorazd; Šubarić, Marin

    2015-01-01

    The first attempts to systematize septal distortions have been given by Cottle who defined four groups of septal deformities: subluxation, large spurs, caudal deflection and tension septum. Fortunately, the variations of the septal deformities show a certain order, thus enabling more precise classification. Mladina was the first to make user-friendly classification of septal deformities in six basic types. He also described the seventh type, named “Passali deformity”, which presents individually, but is always a well-defined combination between some of the previous six types. Mladina types of septal deformities (SD) are divided in two main groups: so called “vertical” deformities (types 1, 2, 3 and 4), and “horizontal” ones (types 5 and 6). This classification was immediately well accepted by rhinologists worldwide and started to be cited from the very beginning. Since then it has been continuously cited increasingly more often, thus making Mladina classification a gold standard whenever clinical researches on nasal septum are concerned. More than forty clinical studies based on this classification have been performed to date. It is extremely important to make a strict distinction between the types of SD since all of them play some specific role in the nasal and general physiology in man. PMID:26167337

  12. Dating Violence among College Students

    ERIC Educational Resources Information Center

    Iconis, Rosemary

    2013-01-01

    Dating violence is a significant problem on college campuses. More than one-fifth of the undergraduate dating population are physically abused by their dating partners and an even greater percentage are psychologically abused. Researchers have identified risk factors for college student dating violence. Preventive interventions are strongly…

  13. Deformations of 3-algebras

    SciTech Connect

    Figueroa-O'Farrill, Jose Miguel

    2009-11-15

    We phrase deformations of n-Leibniz algebras in terms of the cohomology theory of the associated Leibniz algebra. We do the same for n-Lie algebras and for the metric versions of n-Leibniz and n-Lie algebras. We place particular emphasis on the case of n=3 and explore the deformations of 3-algebras of relevance to three-dimensional superconformal Chern-Simons theories with matter.

  14. Principles of rock deformation

    SciTech Connect

    Nicolas, A.

    1987-01-01

    This text focuses on the recent achievements in the analysis of rock deformation. It gives an analytical presentation of the essential structures in terms of kinetic and dynamic interpretation. The physical properties underlying the interpretation of rock structures are exposed in simple terms. Emphasized in the book are: the role of fluids in rock fracturing; the kinematic analysis of magnetic flow structures; the application of crystalline plasticity to the kinematic and dynamic analysis of the large deformation imprinted in many metamorphic rocks.

  15. Polygonal deformation bands

    NASA Astrophysics Data System (ADS)

    Antonellini, Marco; Mollema, Pauline Nella

    2015-12-01

    We report for the first time the occurrence of polygonal faults in sandstone, which is compelling given that layer-bound polygonal fault systems have been observed so far only in fine-grained sediments such as clay and chalk. The polygonal faults are shear deformation bands that developed under shallow burial conditions via strain hardening in dm-wide zones. The edges of the polygons are 1-5 m long. The shear deformation bands are organized as conjugate faults along each edge of the polygon and form characteristic horst-like structures. The individual deformation bands have slip magnitudes ranging from a few mm to 1.5 cm; the cumulative average slip magnitude in a zone is up to 10 cm. The deformation bands heaves, in aggregate form, accommodate a small isotropic horizontal extension (strain <0.005). The individual shear deformation bands show abutting T-junctions, veering, curving, and merging where they mechanically interact. Crosscutting relationships are rare. The interactions of the deformation bands are similar to those of mode I opening fractures. The documented fault networks have important implications for evaluating the geometry of km-scale polygonal fault systems in the subsurface, top seal integrity, as well as constraining paleo-tectonic stress regimes.

  16. Mineralogic and isotopic constraints on impact related clay mineral alteration, in the Woodleigh impact structure, Western Australia

    NASA Astrophysics Data System (ADS)

    Uysal, I. T.; Golding, S. D.; Mory, A. J.; Glikson, A. Y.

    2003-04-01

    , together with stratigraphic age constraints, confirm that the impact event was coeval with the Late Devonian mass extinction. Woodleigh impact-related clay minerals have significantly high δ18O values from 13.4 to 18.9 ppm. The calculated fluid δ18O values ranges from 6.5 to 11.7 ppm that are highly enriched in 18O relative to seawater, meteoric water and most basinal brines and may indicate the hydrothermal fluids interacted with 18O-rich condensed meteoritic components injected into the crater floor.

  17. Laboratory for Radiokrypton Dating

    NASA Astrophysics Data System (ADS)

    Zappala, J. C.; Jiang, W.; Bailey, K. G.; Lu, Z. T.; Mueller, P.; O'Connor, T. P.

    2015-12-01

    Due to its simple production and transport in the terrestrial environment, 81Kr (half-life = 230,000 yr) is the ideal tracer for old water and ice with mean residence times in the range of 105-106 years, a range beyond the reach of 14C. 81Kr-dating is now available to the earth science community at large thanks to the development of an efficient and selective atom counter based on the Atom Trap Trace Analysis (ATTA) method. ATTA is a laser-based atom counting method where individual neutral atoms of the desired isotope are selectively captured by laser beams, and their fluorescence detected via a CCD camera. ATTA is unique among trace analysis techniques in that it is free of interferences from any other isotopes, isobars, atomic or molecular species. The ATTA instrument at Argonne's Laboratory for Radiokrypton Dating is capable of measuring both 81Kr/Kr and 85Kr/Kr ratios of environmental samples in the range of 10-14-10-10. For 81Kr-dating in the age range of 150 kyr - 1500 kyr, the required sample size is 5 micro-L STP of krypton gas, which can be extracted from approximately 100 kg of water or 40 kg of ice. For 85Kr/Kr analysis, the sample size can be smaller by an order of magnitude. We are continually developing the method towards higher counting efficiency, smaller sample sizes requirements, and higher sample throughput rates. In the past four years, we have performed radiokrypton analysis of over 150 groundwater and ice samples extracted by collaborators from all seven continents. Sample collection and purification was performed by groups including the University of Chicago, the University of Illinois at Chicago, the University of Bern, and the International Atomic Energy Agency. This work is supported by the U.S. DOE, Office of Nuclear Physics, under contract DE-AC02-06CH11357.

  18. 210Pb dating

    USGS Publications Warehouse

    Swarzenski, Peter W.

    2014-01-01

    Roughly fifty years ago, a small group of scientists from Belgium and the United States, trying to better constrain ice sheet accumulation rates, attempted to apply what was then know about environmental lead as a potential geochronometer. Thus Goldberg (1963) developed the first principles of the 210Pb dating method, which was soon followed by a paper by Crozaz et al. (1964), who examined accumulation history of Antarctic snow using 210Pb. Shortly thereafter, Koide et al. (1972, 1973) adapted this technique to unravel sediment deposition and accumulation records in deep-sea environments. Serendipitously, they chose to work in a deep basin off California, where an independent and robust age model had already been developed. Krishanswami et al. (1971) extended the use of this technique to lacustrine deposits to reconstruct depositional histories of lake sediment, and maybe more importantly, contaminant inputs and burial. Thus, the powerful tool for dating recent (up to about one century old) sediment deposits was established and soon widely adopted. Today almost all oceanographic or limnologic studies that address recent depositional reconstructions employ 210Pb as one of several possible geochronometers (Andrews et al., 2009; Gale, 2009; Baskaran, 2011; Persson and Helms, 2011). This paper presents a short overview of the principles of 210Pb dating and provides a few examples that illustrate the utility of this tracer in contrasting depositional systems. Potential caveats and uncertainties (Appleby et al., 1986; Binford, 1990; Binford et al., 1993; Smith, 2001; Hancock et al., 2002) inherent to the use and interpretation of 210Pb-derived age-models are also introduced. Recommendations as to best practices for most reliable uses and reporting are presented in the summary.

  19. Vulcanism and Radiocarbon Dates

    DOE R&D Accomplishments Database

    Libby, L. M.; Libby, W. F.

    1972-10-01

    We consider whether the long term perturbation of radiocarbon dates, which is known to be approximately a sin function of period about 8000 years and amplitude of about 8% peak-to-peak, could have been caused in any major part by vulcanism. We conclude that this is not the case. On the contrary, present day volcanoes are a far less important source of inert CO{sub 2} (about 100 fold less) than is man's burning of fossil fuels which has caused the Suess dilution of about 2%. (auth)

  20. Adverse Psychosexual Impact Related to the Treatment of Genital Warts and Cervical Intraepithelial Neoplasia.

    PubMed

    Campaner, Adriana Bittencourt; Vespa Junior, Nelson; Giraldo, Paulo César; Leal Passos, Mauro Romero

    2013-01-01

    Objective. To compare the psychosexual impact related to the treatment of genital warts and cervical intraepithelial neoplasia (CIN) in women. Methods. 75 patients presenting with HPV-induced genital lesions, belonging to one of two patient groups, were included in the study: 29 individuals with genital warts (GWs) and 46 individuals with CIN grades 2 or 3 (CIN 2/3). Initially, medical charts of each woman were examined for extraction of data on the type of HPV-induced infection and treatment administered. Subjects were interviewed to collect sociodemographic data as well as personal, gynecologic, obstetric, and sexual history. After this initial anamnesis, the Sexual Quotient-Female Version (SQ-F) questionnaire was applied to assess sexual function. After application of the questionnaire, patients answered specific questions produced by the researchers, aimed at assessing the impact of the disease and its treatment on their sexual lives. Results. It is noteworthy that patients with CIN 2/3 had statistically similar classification of sexual quotient to patients with GWs (P = 0.115). However, patients with GWs more frequently gave positive answers to the specific questions compared to patients with CIN 2/3. Conclusion. Based on these findings, it is clear that GWs have a greater impact on sexual behavior compared to CIN 2/3. PMID:26316956

  1. Experimental Deformation of Magnetite

    NASA Astrophysics Data System (ADS)

    Till, J. L.; Rybacki, E.; Morales, L. F. G.

    2015-12-01

    Magnetite is an important iron ore mineral and the most prominent Fe-oxide phase in the Earth's crust. The systematic occurrence of magnetite in zones of intense deformation in oceanic core complexes suggests that it may play a role in strain localization in some silicate rocks. We performed a series of high-temperature deformation experiments on synthetic magnetite aggregates and natural single crystals to characterize the rheological behavior of magnetite. As starting material, we used fine-grained magnetite powder that was hot isostatically pressed at 1100°C for several hours, resulting in polycrystalline material with a mean grain size of around 40 μm and containing 3-5% porosity. Samples were deformed to 15-20% axial strain under constant load (approximating constant stress) conditions in a Paterson-type gas apparatus for triaxial deformation at temperatures between 900 and 1100°C and 300 MPa confining pressure. The aggregates exhibit typical power-law creep behavior. At high stresses, samples deformed by dislocation creep exhibit stress exponents close to 3, revealing a transition to near-Newtonian creep with stress exponents around 1.3 at lower stresses. Natural magnetite single crystals deformed at 1 atm pressure and temperatures between 950°C and 1150 °C also exhibit stress exponents close to 3, but with lower flow stresses and a lower apparent activation energy than the aggregates. Such behavior may result from the different oxygen fugacity buffers used. Crystallographic-preferred orientations in all polycrystalline samples are very weak and corroborate numerical models of CPO development, suggesting that texture development in magnetite may be inherently slow compared with lower symmetry phases. Comparison of our results with experimental deformation data for various silicate minerals suggests that magnetite should be weaker than most silicates during ductile creep in dry igneous rocks.

  2. ESR dating of pseudotachylite

    NASA Astrophysics Data System (ADS)

    Shimada, A.; Toyoda, S.; Takagi, H.; Arita, K.

    2002-12-01

    ESR (electron spin resonance) dating method has been used to determine the ages of quaternary events. When a mineral receives natural radiation, a part of paired electrons in quartz are ionized, and are trapped by lattice defects and impurties as unpaired electrons. The amount of unpaired electrons increases with time. The ESR age is obtained by dividing the total dose of natural radiation by the natural dose rate. Gamma ray doses are given to the sample to obtain the total dose by extrapolating the dose response of the signal intensity to the zero ordinate. The natural dose rate is calculated from U, Th, and K concentrations, and so on. Quartz is one of the promising minerals useful for ESR dating. In the present paper, we attempted to obtain ages of a land slide event. We collected pseudotachylite from Lantan, Himalaya. A land of about 4 km in diameter has found to have slid several kilometers resulting in pseudotachylite at the base. The samples were gently crushed sieved and soaked in 6N HCl for 1 night and then in 20% HF for two hours, but quartz grains were too small to be extracted. However, ESR signals of characteristic quartz were observed. As long as the sample is uniform, it is not crucial to extract pure quartz grains. With the usual procedure of ESR dating, gamma ray irradiation and ESR measurements, we obtained accumulated natural doses of 290 to 450 Gy. The concentrations of radioactive elements, K, U, Th, which give most of the natural dose to quartz grains, were measured by the low background gamma ray spectrometry. We obtained 7.62 ppm of uranium, 21.1 ppm of thorium, and 3.72% of K2O. Assuming the cosmic dose rate of 0.1mGy/y, we obtained 6.08 mGy/y as the natural dose rate. The ESR ages are obtained by dividing the accumulated doses by the natural dose rate to be 49ka from Al center signal (an electronic hole trapped at Al impurity in quartz) and 74ka from Ti center signal (an electron trapped at Ti impurity in quartz) for a sample, and 56ka and

  3. Laboratory for Radiokrypton Dating

    NASA Astrophysics Data System (ADS)

    Lu, Z.; Bailey, K.; Jiang, W.; Müller, P.; O'Connor, T. P.; Zappala, J. C.

    2013-12-01

    Due to its simple production and transport processes in the terrestrial environment, the long-lived noble-gas isotope 81Kr (half-life = 230 kyr) is the ideal tracer for studying old water and ice in the age range of 10^5-10^6 years, a range beyond the reach of 14C. 81Kr dating, a concept pursued in the past four decades by numerous laboratories employing a variety of techniques, is now available for the first time to the earth science community at large. This is made possible by the development of ATTA-3 (Jiang et al., GCA 91, 1-6; 2012), an efficient and selective atom counter based on the Atom Trap Trace Analysis method (Chen et al., Science 286, 1139-1141; 1999). The instrument is capable of measuring both 81Kr/Kr and 85Kr/Kr ratios of environmental samples in the range of 10^-14-10^-10. For 81Kr-dating in the age range of 150 - 1,500 kyr, the required sample size is 5 - 10 micro-L STP of krypton gas, which can be extracted from approximately 100 - 200 kg of water or 40 - 80 kg of ice. For 85Kr/Kr analysis, the required sample size is generally smaller by an order of magnitude because of the isotope's higher initial abundance in the atmosphere. The Laboratory for Radiokrypton Dating is currently equipped to analyze up to 120 samples per year. With future equipment upgrades, this limit can be increased as demand grows. In the period since November 2011, the Laboratory has measured both 81Kr/Kr and 85Kr/Kr ratios in over 50 samples that had been extracted by collaborators from six different continents. The samples were from groundwater wells in the Great Artesian Basin (Australia), Guarani Aquifer (Brazil), and Locust Grove (Maryland); from brine wells of the Waste Isolation Pilot Plant (New Mexico); from geothermal steam vents in Yellowstone National Park; from near-surface ice at Taylor Glacier, Antarctica; and from deep mines in South Africa. Sample collection and purification was performed by groups including the University of Illinois at Chicago, University

  4. Vaporization of Deforming Droplets

    NASA Astrophysics Data System (ADS)

    Wang, Yanxing; Chen, Xiaodong; Ma, Dongjun; Yang, Vigor

    2012-11-01

    Droplet deformation is one of the most important factors influencing the evaporation rate. In the present study, high-fidelity numerical simulations of single evaporating droplets with deformation are carried out over a wide range of the Reynolds and Weber numbers. The formulation is based on a complete set of conservation equations for both the liquid and surrounding gas phases. A modified volume-of-fluid (VOF) technique that takes into account heat and mass transfer is used to track the behavior of the liquid/gas interface. Special attention is given to the property conservation, which can be realized by using an iterative algorithm that enforces a divergence constraint in cells containing the interface. The effect of the ambient flow on droplet dynamics and evaporation are investigated systematically. Various underlying mechanisms dictating the droplet characteristics in different deformation regimes are identified. Correlations for the droplet evaporation rate are established in terms of the Reynolds and Weber numbers.

  5. Interfacial Bubble Deformations

    NASA Astrophysics Data System (ADS)

    Seymour, Brian; Shabane, Parvis; Cypull, Olivia; Cheng, Shengfeng; Feitosa, Klebert

    Soap bubbles floating at an air-water experience deformations as a result of surface tension and hydrostatic forces. In this experiment, we investigate the nature of such deformations by taking cross-sectional images of bubbles of different volumes. The results show that as their volume increases, bubbles transition from spherical to hemispherical shape. The deformation of the interface also changes with bubble volume with the capillary rise converging to the capillary length as volume increases. The profile of the top and bottom of the bubble and the capillary rise are completely determined by the volume and pressure differences. James Madison University Department of Physics and Astronomy, 4VA Consortium, Research Corporation for Advancement of Science.

  6. Crustal deformation and earthquakes

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1984-01-01

    The manner in which the Earth's surface deforms during the cycle of stress accumulation and release along major faults is investigated. In an investigation of the crustal deformation associated with a thin channel asthenosphere displacements are reduced from those computed for a half space asthenosphere. A previous finding by other workers that displacements are enhanced when flow is confined to a thin channel is based on several invalid approximations. The major predictions of the finite element model are that the near field postseismic displacements and strain rates are less than those for a half space asthenosphere and that the postseismic strain rates at intermediate distances are greater (in magnitude). The finite width of the asthenosphere ceases to have a significant impact on the crustal deformation pattern when its magnitude exceeds about three lithosphere thicknesses.

  7. Plate motion and deformation

    SciTech Connect

    Minster, B.; Prescott, W.; Royden, L.

    1991-02-01

    Our goal is to understand the motions of the plates, the deformation along their boundaries and within their interiors, and the processes that control these tectonic phenomena. In the broadest terms, we must strive to understand the relationships of regional and local deformation to flow in the upper mantle and the rheological, thermal and density structure of the lithosphere. The essential data sets which we require to reach our goal consist of maps of current strain rates at the earth's surface and the distribution of integrated deformation through time as recorded in the geologic record. Our success will depend on the effective synthesis of crustal kinematics with a variety of other geological and geophysical data, within a quantitative theoretical framework describing processes in the earth's interior. Only in this way can we relate the snapshot of current motions and earth structure provided by geodetic and geophysical data with long-term processes operating on the time scales relevant to most geological processes. The wide-spread use of space-based techniques, coupled with traditional geological and geophysical data, promises a revolution in our understanding of the kinematics and dynamics of plate motions over a broad range of spatial and temporal scales and in a variety of geologic settings. The space-based techniques that best address problems in plate motion and deformation are precise space-geodetic positioning -- on land and on the seafloor -- and satellite acquisition of detailed altimetric and remote sensing data in oceanic and continental areas. The overall science objectives for the NASA Solid Earth Science plan for the 1990's, are to Understand the motion and deformation of the lithosphere within and across plate boundaries'', and to understand the dynamics of the mantle, the structure and evolution of the lithosphere, and the landforms that result from local and regional deformation. 57 refs., 7 figs., 2 tabs.

  8. Lobster claw deformity.

    PubMed

    Agrawal, Ashish; Agrawal, Rahul; Singh, Rajat; Agrawal, Romi; Agrawal, Seema

    2014-01-01

    Endogenous erythroid colony (EEC) syndrome comprise of three cardinal features, i.e. ectrodactyly, ectodermal dysplasia and cleft lip. EEC itself has three different forms. Ectrodactyly (absence of one or more digits) can be present with clefting in the proximal portion of hand or foot known as split hand foot malformation (SHFM) or lobster claw deformity. SHFM can be of four types depending upon the different responsible chromosomal loci. SHFM-4 can be present as pure limb malformation (non-syndromic form). In this article, describes a rare case report of lobster claw deformity patient. PMID:24992861

  9. Nail Deformities and Injuries.

    PubMed

    Tucker, James Rory J

    2015-12-01

    A variety of nail deformities commonly presents in the primary care office. An understanding of nail anatomy coupled with inspection of the nails at routine office visits can reveal undetected disorders. Some problems are benign, and treatment should be attempted by the primary care provider, such as onychomycosis, paronychia, or ingrown toenails. For conditions such as benign melanonychia, longitudinal ridges, isolated Beau lines, and onycholysis, clinicians may offer reassurance to patients who are concerned about the change in their nails. For deformities such as early pterygium or clubbing, a thorough evaluation and referral to an appropriate specialist may be warranted. PMID:26612379

  10. Nanolaminate deformable mirrors

    DOEpatents

    Papavasiliou, Alexandros P.; Olivier, Scot S.

    2009-04-14

    A deformable mirror formed out of two layers of a nanolaminate foil attached to a stiff substrate is introduced. Deformation is provided by an electrostatic force between two of the layers. The internal stiffness of the structure allows for high-spatial-frequency shapes. The nanolaminate foil of the present invention allows for a high-quality mirror surface. The device achieves high precision in the vertical direction by using foils with accurately controlled thicknesses, but does not require high precision in the lateral dimensions, allowing such mirrors to be fabricated using crude lithography techniques. Such techniques allow structures up to about the meter scale to be fabricated.

  11. Nanolaminate deformable mirrors

    DOEpatents

    Papavasiliou, Alexandros P.; Olivier, Scot S.

    2010-04-06

    A deformable mirror formed out of two layers of a nanolaminate foil attached to a stiff substrate is introduced. Deformation is provided by an electrostatic force between two of the layers. The internal stiffness of the structure allows for high-spatial-frequency shapes. The nanolaminate foil of the present invention allows for a high-quality mirror surface. The device achieves high precision in the vertical direction by using foils with accurately controlled thicknesses, but does not require high precision in the lateral dimensions, allowing such mirrors to be fabricated using crude lithography techniques. Such techniques allow structures up to about the meter scale to be fabricated.

  12. Violence in Adolescent Dating Relationships

    ERIC Educational Resources Information Center

    Jouriles, Ernest N.; Platt, Cora; McDonald, Renee

    2009-01-01

    Beginning with a definition of dating and dating violence among adolescents, this article explores the factors which impact such violence. It concludes with a review of two school-based prevention/intervention programs (Safe Dates and The Youth Relationships Project). (Contains 1 table.)

  13. 75 FR 38148 - Finding of No Significant Impact Related to Approval of the Mallinckrodt C-T Phase 2...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-01

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Finding of No Significant Impact Related to Approval of the Mallinckrodt C-T Phase 2 Decommissioning Plan; Mallinckrodt, Inc.; St. Louis, MO The U.S. Nuclear Regulatory Commission (NRC) is considering approval of the Mallinckrodt Inc....

  14. Transfer involving deformed nuclei

    SciTech Connect

    Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.

    1985-03-01

    Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs.

  15. Deformation twins in Hornblende

    USGS Publications Warehouse

    Rooney, T.P.; Riecker, R.E.; Ross, M.

    1970-01-01

    Hornblende deformation twins with twin planes parallel to (101) are produced experimentally in single crystals by compression parallel to the c axis. Twinning occurs at confining pressures from 5 to 15 kilobars and temperatures from 400?? to 600??C (strain rate, 10-5 per second).

  16. Degenerative Spinal Deformity.

    PubMed

    Ailon, Tamir; Smith, Justin S; Shaffrey, Christopher I; Lenke, Lawrence G; Brodke, Darrel; Harrop, James S; Fehlings, Michael; Ames, Christopher P

    2015-10-01

    Degenerative spinal deformity afflicts a significant portion of the elderly and is increasing in prevalence. Recent evidence has revealed sagittal plane malalignment to be a key driver of pain and disability in this population and has led to a significant shift toward a more evidence-based management paradigm. In this narrative review, we review the recent literature on the epidemiology, evaluation, management, and outcomes of degenerative adult spinal deformity (ASD). ASD is increasing in prevalence in North America due to an aging population and demographic shifts. It results from cumulative degenerative changes focused in the intervertebral discs and facet joints that occur asymmetrically to produce deformity. Deformity correction focuses on restoration of global alignment, especially in the sagittal plane, and decompression of the neural elements. General realignment goals have been established, including sagittal vertical axis <50 mm, pelvic tilt <22°, and lumbopelvic mismatch <±9°; however, these should be tailored to the patient. Operative management, in carefully selected patients, yields satisfactory outcomes that appear to be superior to nonoperative strategies. ASD is characterized by malalignment in the sagittal and/or coronal plane and, in adults, presents with pain and disability. Nonoperative management is recommended for patients with mild, nonprogressive symptoms; however, evidence of its efficacy is limited. Surgery aims to restore global spinal alignment, decompress neural elements, and achieve fusion with minimal complications. The surgical approach should balance the desired correction with the increased risk of more aggressive maneuvers. In well-selected patients, surgery yields excellent outcomes. PMID:26378361

  17. MEMS Actuated Deformable Mirror

    SciTech Connect

    Papavasiliou, A; Olivier, S; Barbee, T; Walton, C; Cohn, M

    2005-11-10

    This ongoing work concerns the creation of a deformable mirror by the integration of MEMS actuators with Nanolaminate foils through metal compression boning. These mirrors will use the advantages of these disparate technologies to achieve dense actuation of a high-quality, continuous mirror surface. They will enable advanced adaptive optics systems in large terrestrial telescopes. While MEMS actuators provide very dense actuation with high precision they can not provide large forces typically necessary to deform conventional mirror surfaces. Nanolaminate foils can be fabricated with very high surface quality while their extraordinary mechanical properties enable very thin, flexible foils to survive the rigors of fabrication. Precise metal compression bonding allows the attachment of the fragile MEMS actuators to the thin nanolaminate foils without creating distortions at the bond sites. This paper will describe work in four major areas: (1) modeling and design, (2) bonding development, (3) nanolaminate foil development, (4) producing a prototype. A first-principles analytical model was created and used to determine the design parameters. A method of bonding was determined that is both strong, and minimizes the localized deformation or print through. Work has also been done to produce nanolaminate foils that are sufficiently thin, flexible and flat to be deformed by the MEMS actuators. Finally a prototype was produced by bonding thin, flexible nanolaminate foils to commercially available MEMS actuators.

  18. Density Variations in Quartz As a Key for Deciphering Impact-Related Ultrasonic Sounding (Rajlich's Hypothesis)?

    NASA Astrophysics Data System (ADS)

    Mestan, J.; Alvarez Polanco, E. I.

    2014-12-01

    Ultrasound is a form of mechanical energy with a frequency greater than ≈ 20 kHz (upper human hearing limit). It is used in many scientific as well as industrial fields. Most modern applications of ultrasound utilize sources which are either piezoelectric or magnetostrictive (Benwell et Bly 1987). A meteorite impact has been considered to be an ultrasound source during last years (Rajlich 2011). Rajlich (2014) is coming with a hypothesis that white planes made of microcavities in Bohemian quartz have their origin in an impact-related ultrasonic sounding. The Bohemian Massif has been considered to be one of the largest impact craters in whole of the world (Papagiannis et El-Baz 1988, Papagiannis 1989, Rajlich 2014). Rajlich's hypothesis implies a liquid behavior of quartz during the impact event. We state that then there have to exist planes of slightly higher density than their surroundings together with planes of microcavities. They should intersect each other without mutual influencing (as in a case of planes made of microcavities). Because physics of ultrasound during an impact event is a brand new and unknown field, we try to choose a simple way of its cognition. It is possible to take the sine wave and set 3 requirements. (1) There exist some surroundings of points of peak amplitudes. (2) These surroundings are of higher density (compression) or lower density (rarefaction) than the mean density of quartz. (3) The difference between the higher/lower and surrounding density is measurable. There was done an experimental study of Bohemian quartz using QCT bone densitometry at the Radiology Munich. Quartz with a size of ≈ 5 x 8 cm absorbed too much RTG radiation (kV 140, mAs 330), which made a picture of internal structure impossible. We propose another techniques and appeal to other scientists to face this challenge. If Bohemian quartz has a harmonically distributed density, we consider it to be a support for Rajlich's hypothesis. AcknowledgementsWe would like

  19. Radiocarbon Dating, Memories, and Hopes

    DOE R&D Accomplishments Database

    Libby, W. F.

    1972-10-01

    The history of radiocarbon dating from 1939 to the present is reviewed. The basic principles of radiocarbon dating are that cosmic rays make living things radioactive with {sup 14}C to a certain level fixed by the environment and that at death the intake of food stops so no replenishment of the {sup 14}C steadily lost by the immutable decay occurs. Therefore measurement of the degree of decay gives the time lapse since death, i.e., the radiocarbon age. The equipment developed and experiments performed to measure the specific activity of specimens to be dated are described. The results obtained by world-wide experimenters are discussed. These showed that on simultaneity radiocarbon dating is apparently reliable but that absolute dates may be incorrect by as much as 600 to 700 y. The value of radiocarbon dating to archaeologists, geologists, climatologists, and historians is stressed. (LCL)

  20. Probing deformed quantum commutators

    NASA Astrophysics Data System (ADS)

    Rossi, Matteo A. C.; Giani, Tommaso; Paris, Matteo G. A.

    2016-07-01

    Several quantum gravity theories predict a minimal length at the order of magnitude of the Planck length, under which the concepts of space and time lose their physical meaning. In quantum mechanics, the insurgence of such a minimal length can be described by introducing a modified position-momentum commutator, which in turn yields a generalized uncertainty principle, where the uncertainty on position measurements has a lower bound. The value of the minimal length is not predicted by theories and must be estimated experimentally. In this paper, we address the quantum bound to the estimability of the minimal uncertainty length by performing measurements on a harmonic oscillator, which is analytically solvable in the deformed algebra induced by the deformed commutation relations.

  1. [Babies with cranial deformity].

    PubMed

    Feijen, Michelle M W; Claessens, Edith A W M Habets; Dovens, Anke J Leenders; Vles, Johannes S; van der Hulst, Rene R W J

    2009-01-01

    Plagiocephaly was diagnosed in a baby aged 4 months and brachycephaly in a baby aged 5 months. Positional or deformational plagio- or brachycephaly is characterized by changes in shape and symmetry of the cranial vault. Treatment options are conservative and may include physiotherapy and helmet therapy. During the last two decades the incidence of positional plagiocephaly has increased in the Netherlands. This increase is due to the recommendation that babies be laid on their backs in order to reduce the risk of sudden infant death syndrome. We suggest the following: in cases of positional preference of the infant, referral to a physiotherapist is indicated. In cases of unacceptable deformity of the cranium at the age 5 months, moulding helmet therapy is a possible treatment option. PMID:19857299

  2. Partially segmented deformable mirror

    DOEpatents

    Bliss, Erlan S.; Smith, James R.; Salmon, J. Thaddeus; Monjes, Julio A.

    1991-01-01

    A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp.

  3. Partially segmented deformable mirror

    DOEpatents

    Bliss, E.S.; Smith, J.R.; Salmon, J.T.; Monjes, J.A.

    1991-05-21

    A partially segmented deformable mirror is formed with a mirror plate having a smooth and continuous front surface and a plurality of actuators to its back surface. The back surface is divided into triangular areas which are mutually separated by grooves. The grooves are deep enough to make the plate deformable and the actuators for displacing the mirror plate in the direction normal to its surface are inserted in the grooves at the vertices of the triangular areas. Each actuator includes a transducer supported by a receptacle with outer shells having outer surfaces. The vertices have inner walls which are approximately perpendicular to the mirror surface and make planar contacts with the outer surfaces of the outer shells. The adhesive which is used on these contact surfaces tends to contract when it dries but the outer shells can bend and serve to minimize the tendency of the mirror to warp. 5 figures.

  4. Ice deformation near SHEBA

    NASA Astrophysics Data System (ADS)

    Lindsay, R. W.

    2002-10-01

    The deformation rate of sea ice is a key parameter for determining the evolution of the ice thickness distribution. It determines the rate of new ice formation through opening and the rate of ridging through closing and shear. An extensive suite of ground-based and satellite-based measurements of ice motion is used to construct a daily time series of the ice velocity and deformation in the vicinity of the Surface Heat Budget of the Arctic Ocean (SHEBA) ice camp that is suitable for forcing a model of the ice thickness distribution. The velocity is interpolated to a square grid that remains centered on the camp, has a spacing of 25 km, is 400 km on a side, and is determined for a 371-day period from 2 October 1997 to 7 October 1998. Velocity measurements from buoys, Advanced Very High Resolution Radiometer (AVHRR), Special Sensor Microwave/Imager (SSMI), and Radarsat Geophysical Processing System (RGPS) are merged using optimal interpolation and a Kalman filter approach. The deformation rate is taken directly from the RGPS measurements when available. The daily total deformation rate measured on a scale of 100 km near the camp averaged 2.21% d-1, and the standard deviation was 1.78% d-1. The divergence was positive in the early winter and negative through most of the spring and summer. There were two major opening/closing events, one in January and one at the end of July. The net divergence over the year was very near zero. The vorticity indicated a net rotation of 87° over the year, with the winter showing strong anticyclonic turning and the summer showing strong cyclonic turning.

  5. Covariant deformed oscillator algebras

    NASA Technical Reports Server (NTRS)

    Quesne, Christiane

    1995-01-01

    The general form and associativity conditions of deformed oscillator algebras are reviewed. It is shown how the latter can be fulfilled in terms of a solution of the Yang-Baxter equation when this solution has three distinct eigenvalues and satisfies a Birman-Wenzl-Murakami condition. As an example, an SU(sub q)(n) x SU(sub q)(m)-covariant q-bosonic algebra is discussed in some detail.

  6. Deformable micro torque swimmer

    NASA Astrophysics Data System (ADS)

    Ishikawa, Takuji; Tanaka, Tomoyuki; Omori, Toshihiro; Imai, Yohsuke

    2015-11-01

    We investigated the deformation of a ciliate swimming freely in a fluid otherwise at rest. The cell body was modeled as a capsule with a hyper elastic membrane enclosing Newtonian fluid. Thrust forces due to the ciliary beat were modeled as torques distributed above the cell body. Effects of the membrane elasticity, the aspect ratio of cell's reference shape and the density difference between the cell and the surrounding fluid were investigated. The results showed that the cell deformed like heart shape when Capillary number (Ca) was sufficiently large, and the swimming velocity decreased as Ca was increased. The gravity effect on the membrane tension suggested that the upwards and downwards swimming velocities of Paramecium might be reglated by the calcium ion channels distributed locally around the anterior end. Moreover, the gravity induced deformation made a cell directed vertically downwards, which resulted in a positive geotaxis like behavior with physical origin. These results are important to understand physiology of ciliate's biological responses to mechanical stimuli.

  7. Deformation of Wrinkled Graphene

    PubMed Central

    2015-01-01

    The deformation of monolayer graphene, produced by chemical vapor deposition (CVD), on a polyester film substrate has been investigated through the use of Raman spectroscopy. It has been found that the microstructure of the CVD graphene consists of a hexagonal array of islands of flat monolayer graphene separated by wrinkled material. During deformation, it was found that the rate of shift of the Raman 2D band wavenumber per unit strain was less than 25% of that of flat flakes of mechanically exfoliated graphene, whereas the rate of band broadening per unit strain was about 75% of that of the exfoliated material. This unusual deformation behavior has been modeled in terms of mechanically isolated graphene islands separated by the graphene wrinkles, with the strain distribution in each graphene island determined using shear lag analysis. The effect of the size and position of the Raman laser beam spot has also been incorporated in the model. The predictions fit well with the behavior observed experimentally for the Raman band shifts and broadening of the wrinkled CVD graphene. The effect of wrinkles upon the efficiency of graphene to reinforce nanocomposites is also discussed. PMID:25765609

  8. Treatment of Madelung's deformity.

    PubMed

    Saffar, P; Badina, A

    2015-12-01

    Treatment of Madelung's deformity is still controversial. We reviewed retrospectively 19 patients with Madelung's deformity (two bilateral, 21 cases) who underwent surgery to the radius and ulna to improve range of motion, decrease pain and improve appearance of the wrist. Nineteen patients underwent 21 distal radial osteotomy procedures using three different techniques: subtraction, addition or dome osteotomy. Ulnar shortening and redirection of the distal ulna was performed in 12 cases; a long oblique osteotomy was used in 10 of these cases. The Sauvé-Kapandji technique was performed in five cases, an ulnar distal epiphysiodesis in two cases and a combination of osteotomy and epiphysiodesis in one case. The aim was to reduce the distal radial slope and to restore the orientation and congruity of the distal radio-ulnar joint and to improve its function. Pain was reduced as a result of the procedure: more than 75% of the cases had no or intermittent pain at the review. Pronation improved from 63° to 68° (P=0.467, not significant) and supination improved from 48° to 72° on average (P=0.034, significant). Grip strength increased from 11 to 18 kgf (P=0.013, significant). Madelung's deformity is not always a benign condition and it responds well to corrective osteotomies. PMID:26525609

  9. Supertransvectants, cohomology, and deformations

    NASA Astrophysics Data System (ADS)

    Ben Fraj, Nizar; Laraiedh, Ismail; Omri, Salem

    2013-02-01

    Over the (1, N)-dimensional real superspace, N = 2, 3, we classify {osp}(N|2)-invariant binary differential operators acting on the superspaces of weighted densities, where {osp}(N|2) is the orthosymplectic Lie superalgebra. This result allows us to compute the first differential {osp}(N|2)-relative cohomology of the Lie superalgebra K(N) of contact vector fields with coefficients in the superspace of linear differential operators acting on the superspaces of weighted densities. We classify generic formal {osp}(3|2)-trivial deformations of the K(3)-module structure on the superspaces of symbols of differential operators. We prove that any generic formal {osp}(3|2)-trivial deformation of this K(3)-module is equivalent to its infinitesimal part. This work is the simplest generalization of a result by the first author et al. [Basdouri, I., Ben Ammar, M., Ben Fraj, N., Boujelbene, M., and Kammoun, K., "Cohomology of the Lie superalgebra of contact vector fields on {K}^{1|1} and deformations of the superspace of symbols," J. Nonlinear Math. Phys. 16, 373 (2009), 10.1142/S1402925109000431].

  10. VIEW OF DATE DRIVE, SHOWING DATE PALMS. NOTE TRELLIS ON ...

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

    VIEW OF DATE DRIVE, SHOWING DATE PALMS. NOTE TRELLIS ON TYPE 11 FACILITY, FACILITY 808. VIEW FACING NORTHWEST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  11. Nanoscale Deformable Optics

    NASA Technical Reports Server (NTRS)

    Strauss, Karl F.; Sheldon, Douglas J.

    2011-01-01

    Several missions and instruments in the conceptual design phase rely on the technique of interferometry to create detectable fringe patterns. The intimate emplacement of reflective material upon electron device cells based upon chalcogenide material technology permits high-speed, predictable deformation of the reflective surface to a subnanometer or finer resolution with a very high degree of accuracy. In this innovation, a layer of reflective material is deposited upon a wafer containing (perhaps in the millions) chalcogenic memory cells with the reflective material becoming the front surface of a mirror and the chalcogenic material becoming a means of selectively deforming the mirror by the application of heat to the chalcogenic material. By doing so, the mirror surface can deform anywhere from nil to nanometers in spots the size of a modern day memory cell, thereby permitting realtime tuning of mirror focus and reflectivity to mitigate aberrations caused elsewhere in the optical system. Modern foundry methods permit the design and manufacture of individual memory cells having an area of or equal to the Feature (F) size of the design (assume 65 nm). Fabrication rules and restraints generally require the instantiation of one memory cell to another no closer than 1.5 F, or, for this innovation, 90 nm from its neighbor in any direction. Chalcogenide is a semiconducting glass compound consisting of a combination of chalcogen ions, the ratios of which vary according to properties desired. It has been shown that the application of heat to cells of chalcogenic material cause a large alteration in resistance to the range of 4 orders of magnitude. It is this effect upon which chalcogenidebased commercial memories rely. Upon removal of the heat source, the chalcogenide rapidly cools and remains frozen in the excited state. It has also been shown that the chalcogenide expands in volume because of the applied heat, meaning that the coefficient of expansion of chalcogenic

  12. Radiocarbon Dating: An Annotated Bibliography.

    ERIC Educational Resources Information Center

    Fortine, Suellen

    This selective annotated bibliography covers various sources of information on the radiocarbon dating method, including journal articles, conference proceedings, and reports, reflecting the most important and useful sources of the last 25 years. The bibliography is divided into five parts--general background on radiocarbon, radiocarbon dating,…

  13. National Date Palm Germplasm Repository

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The National Clonal Germplasm Repository for Citrus & Dates (NCGRCD), located in Riverside, California USA, is a project of the Agricultural Research Service (ARS) of the United States Department of Agriculture (USDA). The NCGRCD maintains a collection of germplasm of date palm (Phoneix dactylifera ...

  14. Hydration rind dates rhyolite flows.

    PubMed

    Friedman, I

    1968-02-23

    Hydration of obsidian has been used to date rhyolite flows, containing obsidian or porphyritic glass, at Glass Mountain (Medicine Lake Highlands) and Mono Lake, California. The method is simple and rapid and can be used to date flows that erupted between 200 and approximately 200,000 years ago. PMID:17768978

  15. Hydration rind dates rhyolite flows

    USGS Publications Warehouse

    Friedman, I.

    1968-01-01

    Hydration of obsidian has been used to date rhyolite flows, containing obsidian or porphyritic glass, at Glass Mountain (Medicine Lake Highlands) and Mono Lake, California. The method is simple and rapid and can be used to date flows that erupted between 200 and approximately 200,000 years ago.

  16. Experimental studies on deformation at high pressures using the deformation-DIA

    NASA Astrophysics Data System (ADS)

    Mei, S.; Durham, W. B.; Li, L.; Weidner, D. J.; Wang, Y.

    2003-04-01

    -situ is <1 micronmeter and ~100 MPa, respectively. We are optimistic that stress resolution can be improved by an order of magnitude in the near future. To date we have carried out constant displacement rate compression tests at rates of ~1 x 10-5 to 4 x 10-4/s over shortening strains of 10 - 30% at temperatures of 773 - 1473 K and pressures of 5 - 2 GPa. With the success of these preliminary experi-ments, there is promise that the D-DIA can be used to conduct quantitative deformation experiments at P-T conditions approaching those of Earth's transition zone.

  17. Formation and subdivision of deformation structures during plastic deformation.

    PubMed

    Jakobsen, Bo; Poulsen, Henning F; Lienert, Ulrich; Almer, Jonathan; Shastri, Sarvjit D; Sørensen, Henning O; Gundlach, Carsten; Pantleon, Wolfgang

    2006-05-12

    During plastic deformation of metals and alloys, dislocations arrange in ordered patterns. How and when these self-organization processes take place have remained elusive, because in situ observations have not been feasible. We present an x-ray diffraction method that provided data on the dynamics of individual, deeply embedded dislocation structures. During tensile deformation of pure copper, dislocation-free regions were identified. They showed an unexpected intermittent dynamics, for example, appearing and disappearing with proceeding deformation and even displaying transient splitting behavior. Insight into these processes is relevant for an understanding of the strength and work-hardening of deformed materials. PMID:16690859

  18. Deformation T-Cup: A new Kawai-style deformation device capable of controlled strain-rate deformation at pressures in excess of 20 GPa

    NASA Astrophysics Data System (ADS)

    Hunt, S. A.; Dobson, D. P.; Santangeli, J. R.; McCormack, R.; Li, L.; Whitaker, M. L.; Vaughan, M. T.; Weidner, D. J.

    2012-12-01

    the cubic DIA-type apparatus and the Deformation-DIA. The results of ultra-high pressure deformation experiments performed to date will be presented, along with the technical specifications of the DT-Cup.

  19. Deformable spanners and applications.

    PubMed

    Gao, Jie; Guibas, Leonidas J; Nguyen, An

    2006-08-01

    For a set S of points in ℝ(d), an s-spanner is a subgraph of the complete graph with node set S such that any pair of points is connected via some path in the spanner whose total length is at most s times the Euclidean distance between the points. In this paper we propose a new sparse (1 + ε)-spanner with O(n/ε(d)) edges, where ε is a specified parameter. The key property of this spanner is that it can be efficiently maintained under dynamic insertion or deletion of points, as well as under continuous motion of the points in both the kinetic data structures setting and in the more realistic blackbox displacement model we introduce. Our deformable spanner succinctly encodes all proximity information in a deforming point cloud, giving us efficient kinetic algorithms for problems such as the closest pair, the near neighbors of all points, approximate nearest neighbor search (aka approximate Voronoi diagram), well-separated pair decompositions, and approximate k-centers. PMID:21165161

  20. Deformable spanners and applications

    PubMed Central

    Guibas, Leonidas J.; Nguyen, An

    2010-01-01

    For a set S of points in ℝd, an s-spanner is a subgraph of the complete graph with node set S such that any pair of points is connected via some path in the spanner whose total length is at most s times the Euclidean distance between the points. In this paper we propose a new sparse (1 + ε)-spanner with O(n/εd) edges, where ε is a specified parameter. The key property of this spanner is that it can be efficiently maintained under dynamic insertion or deletion of points, as well as under continuous motion of the points in both the kinetic data structures setting and in the more realistic blackbox displacement model we introduce. Our deformable spanner succinctly encodes all proximity information in a deforming point cloud, giving us efficient kinetic algorithms for problems such as the closest pair, the near neighbors of all points, approximate nearest neighbor search (aka approximate Voronoi diagram), well-separated pair decompositions, and approximate k-centers. PMID:21165161

  1. Ultrasoft, highly deformable microgels.

    PubMed

    Bachman, Haylee; Brown, Ashley C; Clarke, Kimberly C; Dhada, Kabir S; Douglas, Alison; Hansen, Caroline E; Herman, Emily; Hyatt, John S; Kodlekere, Purva; Meng, Zhiyong; Saxena, Shalini; Spears, Mark W; Welsch, Nicole; Lyon, L Andrew

    2015-03-14

    Microgels are colloidally stable, hydrogel microparticles that have previously been used in a range of (soft) material applications due to their tunable mechanical and chemical properties. Most commonly, thermo and pH-responsive poly(N-isopropylacrylamide) (pNIPAm) microgels can be fabricated by precipitation polymerization in the presence of the co-monomer acrylic acid (AAc). Traditionally pNIPAm microgels are synthesized in the presence of a crosslinking agent, such as N,N'-methylenebisacrylamide (BIS), however, microgels can also be synthesized under 'crosslinker free' conditions. The resulting particles have extremely low (<0.5%), core-localized crosslinking resulting from rare chain transfer reactions. AFM nanoindentation of these ultralow crosslinked (ULC) particles indicate that they are soft relative to crosslinked microgels, with a Young's modulus of ∼10 kPa. Furthermore, ULC microgels are highly deformable as indicated by a high degree of spreading on glass surfaces and the ability to translocate through nanopores significantly smaller than the hydrodynamic diameter of the particles. The size and charge of ULCs can be easily modulated by altering reaction conditions, such as temperature, monomer, surfactant and initiator concentrations, and through the addition of co-monomers. Microgels based on the widely utilized, biocompatible polymer polyethylene glycol (PEG) can also be synthesized under crosslinker free conditions. Due to their softness and deformability, ULC microgels are a unique base material for a wide variety of biomedical applications including biomaterials for drug delivery and regenerative medicine. PMID:25648590

  2. Measuring deformations with deflectometry

    NASA Astrophysics Data System (ADS)

    Li, Wansong; Huke, Philipp; Burke, Jan; von Kopylow, Christoph; Bergmann, Ralf B.

    2014-07-01

    Phase-measuring deflectometry is a powerful method to measure reflective surfaces. It is relatively easy to extract slope and curvature information from the measured phase maps; however, retrieving shape information depends very sensitively on the calibration of the camera and the geometry of the measurement system. Whereas we have previously demonstrated shape uncertainties below 1 μm, the range below 100 nm is currently inaccessible to deflectometric shape measurement. On the other hand, the astounding sensitivity of deflectometry can be put to good use for deformation measurements. The evaluation of corresponding shape differences rather than absolute shapes is much less susceptible to system calibration errors and its resolution is given mostly by the measurement system's sensitivity. We give an overview of recent progress in difference deflectometry. Firstly we show results from solar mirror substrates under load to detect flaws with high sensitivity. Secondly we present a preliminary simulation study of achievable deformation-measurement uncertainties to assess the feasibility of deflectometric characterisation of actuator performance and gravity sag for the mirror segments of the European Extremely Large Telescope (E-ELT). Results for the relevant Zernike terms show reliable detection of Zernike coefficients at the 25 nm level. Random artefacts related to noise in the phase measurements are seen to translate into bogus Zernike terms, and we discuss possible mitigation techniques to enhance the sensitivity and accuracy further.

  3. Radiocarbon dating of terrestrial carbonates

    USGS Publications Warehouse

    Pigati, Jeffrey S.

    2014-01-01

    Terrestrial carbonates encompass a wide range of materials that potentially could be used for radiocarbon (14C) dating. Biogenic carbonates, including shells and tests of terrestrial and aquatic gastropods, bivalves, ostracodes, and foraminifera, are preserved in a variety of late Quaternary deposits and may be suitable for 14C dating. Primary calcareous deposits (marls, tufa, speleothems) and secondary carbonates (rhizoliths, fracture fill, soil carbonate) may also be targeted for dating when conditions are favorable. This chapter discusses issues that are commonly encountered in 14C dating of terrestrial carbonates, including isotopic disequilibrium and open-system behavior, as well as methods used to determine the reliability of ages derived from these materials. Recent methodological advancements that may improve the accuracy and precision of 14C ages of terrestrial carbonates are also highlighted.

  4. Dating sediments using luminescence signals

    SciTech Connect

    Wintle, A. )

    1993-05-01

    Before siting a nuclear power station or a nuclear waste repository, it is necessary to establish that the area has been free of earthquake activity for a sufficient period of time. Evidence of past earthquake activity is often provided by faults in surface sediments. Age limits for fault formation can be set by obtaining the depositional ages of the sediment unit in which the fault was formed and the overlying sediment. A useful technique would be one that dating could be applied to the mineral grains that make up the sediments and that would give the time that has passed since the grains were blown or washed into position. Luminescence dating techniques, of which the most well known is thermo-luminescence (TL), provide such information. This approach has been successful in dating movement on the Wasatch Fault in Utah. A combination of TL and radiocarbon dates indicated that three faulting events had occurred within the past 5000 years. 2 refs., 1 fig.

  5. Ovulation and Due Date Calculator

    MedlinePlus

    ... Mom-to-be tools Ovulation and due date calculator Preconception health quiz Pregnancy know-how quiz Government ... Pregnancy > Pregnancy This information in Spanish ( en español ) Calculator Content last updated September 27, 2010. Resources last ...

  6. Microscale radiocarbon dating of paintings

    NASA Astrophysics Data System (ADS)

    Hendriks, Laura; Hajdas, Irka; McIntyre, Cameron; Küffner, Markus; Scherrer, Nadim C.; Ferreira, Ester S. B.

    2016-03-01

    In this paper, radiocarbon dating of paintings using minimal sample sizes has been investigated, in an effort to address the problem of limited access to sample material in paintings. 14C analyses were conducted on signed and dated paintings from two Swiss artists of the twentieth century. The selected paintings dated from the 1930s and 1960s, provided the opportunity to evaluate the dating accuracy on paintings realized before and after 1950 AD when the 14C bomb peak was created, as a result of the nuclear tests conducted in the 1950/1960s. The work focused on the one hand on minimizing the size of the canvas sample required for accelerator mass spectrometer radiocarbon measurement on the gas ion source of the MICADAS and, on the other hand, on testing the possibility of dating the organic binder of the paint. Following careful characterization of the paint composition by X-ray fluorescence spectroscopy, Fourier transformed infrared spectroscopy, and Raman spectroscopy, paints containing no other carbon source than the natural organic binder were identified and dated.

  7. Direct dating of human fossils.

    PubMed

    Grün, Rainer

    2006-01-01

    The methods that can be used for the direct dating of human remains comprise of radiocarbon, U-series, electron spin resonance (ESR), and amino acid racemization (AAR). This review gives an introduction to these methods in the context of dating human bones and teeth. Recent advances in ultrafiltration techniques have expanded the dating range of radiocarbon. It now seems feasible to reliably date bones up to 55,000 years. New developments in laser ablation mass spectrometry permit the in situ analysis of U-series isotopes, thus providing a rapid and virtually non-destructive dating method back to about 300,000 years. This is of particular importance when used in conjunction with non-destructive ESR analysis. New approaches in AAR analysis may lead to a renaissance of this method. The potential and present limitations of these direct dating techniques are discussed for sites relevant to the reconstruction of modern human evolution, including Florisbad, Border Cave, Tabun, Skhul, Qafzeh, Vindija, Banyoles, and Lake Mungo. PMID:17103430

  8. Learning Deformable Shape Manifolds

    PubMed Central

    Rivera, Samuel; Martinez, Aleix

    2011-01-01

    We propose an approach to shape detection of highly deformable shapes in images via manifold learning with regression. Our method does not require shape key points be defined at high contrast image regions, nor do we need an initial estimate of the shape. We only require sufficient representative training data and a rough initial estimate of the object position and scale. We demonstrate the method for face shape learning, and provide a comparison to nonlinear Active Appearance Model. Our method is extremely accurate, to nearly pixel precision and is capable of accurately detecting the shape of faces undergoing extreme expression changes. The technique is robust to occlusions such as glasses and gives reasonable results for extremely degraded image resolutions. PMID:22308002

  9. Dating of Modern Human Evolution

    NASA Astrophysics Data System (ADS)

    Grun, R.

    Dating studies on palaoeanthropological sites is usually carried out on material associ- ated with the human remains, such as the sediment, charcoal or other fauna rather than the human specimen itself. The reason lies in the fact that most dating techniques are destructive and because the hominid remains are too rare to be sacrificed for dating. This indirect dating approach is in many cases not satisfactory, because: (i) the human remains are often buried into the sediments and the association with other materials is uncertain (e.g. Skhul, Qafzeh, etc.); (ii) faunal remains or minerals from the sediment are re-worked from older deposits (see e.g. present discussion of the age of the Homo erectus remains in Indonesia; (iii) the hominid fossils were discovered at a time when no careful excavations were carried out and it is impossible to correlate the specimen with other datable material (which applies tonearly 90% of all palaeoanthropological specimens). For example, the hominid burial site of Qafzeh in Israel has been dated by several independent dating laboratories with a multitude of methods. However, the data are still not accepted by some because the dating has not been carried out on the hominid specimen. Until recently, hominid fossils could only be dated by radiocarbon. This method reaches back to about 40,000 years. As a consequence, all the older fossils could not be analysed and many important questions in our understanding of human evolution could not be addressed. Human remains are scarce and extremely valuable, therefore any sort of destruction has to be kept to an absolute minimum. This is of particular importance in Australia where any human fossils are sacred. Thus, for the analysis of hominid material it was necessary to develop a more or less non-destructive techniques. This has been ac- complished in recent years by the application of ESR dating of tooth enamel and a combination of gamma spectrometric and TIMS U-series dating of bones. The exam

  10. IBA in deformed nuclei

    SciTech Connect

    Casten, R.F.; Warner, D.D.

    1982-01-01

    The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for /sup 168/Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong ..beta.. ..-->.. ..gamma.. transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the ..beta.. ..-->.. ..gamma.. transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ..delta..K=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics.

  11. Rejuvenation effects during plastic deformation of Zircon: geochronological implications

    NASA Astrophysics Data System (ADS)

    Kovaleva, Elizaveta; Klötzli, Urs

    2013-04-01

    Zircon is one of the most stable accessory minerals known on the Earth; it was believed that zircon isotopic ages mostly record primary igneous crystallization events. It is true until the mineral is not affected by plastic deformation or other disturbing events during its life after crystallization. Zircon may deform by the recovery/subgrain rotation recrystallisation that indicates formation and migration of dislocations under crustal conditions. Deformation occurs at depth due to stresses associated with collision of the phases, and forms such microstructures as low-angle boundaries (Reddy et al., 2007). Low-angle boundaries act as fluid migration paths and elements diffusion paths. Facilitating Pb, Ti, U, Th and trace elements mobility in the crystalline zircon, these structures can change chemical, REE and isotopic composition of certain grain's parts (Reddy and Timms, 2010) and lead to isotopic resetting in the mineral domains. Since the isotopic age of the domains of single crystal can vary, it should be possible to recognize and interpret this variation and distinguish the timing of different high-temperature deformation events. Zircon can preserve low-angle boundaries and associated age disturbance under lower-crust temperatures for billions of years (Moser et al., 2009). Electron backscatter diffraction (EBSD) allows us to make microstructural-crystallographic analyses in order to measure the crystallographic orientations in crystalline material. EBSD mapping is supposed to be able to constrain potential diffusion pathways in minerals. It can indicate areas of damaged crystalline structure, helps to examine substructures of minerals used in radiometric dating and to assess the potential for resetting of ages by deformation events (Reddy et al., 2007). In this research we are trying to answer a list of questions, related to isotopic resetting due to deformation: What is the behavior of zircons which were plastically deformed during metamorphic-deformation

  12. Application of rock varnish dating of quaternary surficial deposits in determining times of fault movement

    SciTech Connect

    Harrington, C.D.

    1987-01-01

    Rock varnish, a coating commonly found on rock surfaces in arid and semiarid regions, has a significant potential in paleoseismic studies, as a wide variety of Quaternary surfaces and surficial deposits can be dated with the rock varnish technique. If the formation of geomorphic surfaces or surficial deposits can be related to times of faulting or if faulting has broken or deformed such features, then rock varnish dating can be used to constrain maximum and minimum times of motion on the related fault.

  13. Deformation of olivine at high pressures using the Deformation-DIA

    NASA Astrophysics Data System (ADS)

    Mei, S.; Durham, W. B.; Wang, Y.

    2003-12-01

    The rheological behavior of olivine, the most abundant component of the Earth's upper mantle, under high pressures is essential for understanding the dynamic processes occurring within the Earth's interior. Conventional gas- and solid-medium experiments to date have been limited to pressures of about 3 GPa. We report here results from recent tests on olivine using the Deformation-DIA (D-DIA). The D-DIA is capable of constant-pressure deformation tests at pressures to 15 GPa and is configured to allow operation at a synchrotron x-ray beam line in order to provide in-situ measurement of pressure, differential stress, and sample length as a function of time. Experiments have been conducted on polycrystalline olivine samples cold-pressed from mixtures of olivine plus 5% enstatite powder. A 1 mm long x 1.1 mm diameter sample is encapsulated with 0.025-mm thick Ni foil, and assembled along with fully-densified Al2O3 or MgO pistons, a boron nitride sleeve, and graphite resistance heater into a 6-mm edge length cubic pressure medium of boron-epoxy resin. During experiments, the cell is first pressurized isotropically to desired levels and then deformed in compression at constant pressure. Experiments have been conducted at constant displacement rates of ˜ 0.5 - 8 x 10-5 s-1 over axial strains of 10 -20% at temperatures of 773 -1473 K and pressures of ˜ 5 - 6 GPa. The oxygen fugacity and silica activity of the olivine sample are buffered by Ni/NiO and the presence of enstatite, respectively. Using x-ray diffraction, we determine pressure (i.e., mean stress) and differential stress from the strain of various lattice planes measured as a function of orientation with respect to the stress field. At this point we are able to measure elastic strains from several prominent reflections in the olivine, and they indicate qualitatively that the in situ environment is significantly nonhydrostatic. For polycrystalline olivine deformed at high temperature and a constant rate of

  14. Late Cenozoic Deformation in the Western Tarim Basin, NW China

    NASA Astrophysics Data System (ADS)

    Thompson, J. A.; Burbank, D. W.; Chen, J.; Li, T.

    2009-12-01

    The Tian Shan in NW China is one of the most active regions of intracontinental deformation in the world, accommodating a large fraction (~40%) of the shortening from the Indo-Eurasian collision. The western Tarim Basin, situated between the southern Tian Shan and Pamir Mountains, manifests this deformation through a series of east-west trending fault-related folds that have formed during the late Cenozoic. Previous studies in this region have focused on the kinematics, style, and timing of detachment folds related to folding within the foreland basin of the southern Tian Shan. In contrast, this study focuses on the deformation caused by fault-propagation folding resulting from the northward movement of the Pamir. The rates of deformation are calculated using a combination of optically stimulated luminescence (OSL) ages, structural mapping and differential GPS surveys of fault scarps and deformed terrace surfaces crossing active folds. OSL dating provides the time since the sediment was last exposed to daylight, i.e., time since burial. Consequently, OSL is useful for dating the abandonment of terrace surfaces due to tectonic (fold growth) or climatic events. OSL quartz samples were collected from silt lenses within gravel topping the terraces. Most of the quartz OSL signals are weak, thus several grain sizes (silt (4-11 µm, 8-15 µm) and sand (90-125 µm)) were analyzed and different integrations of the shine-down curves were explored to calculate equivalent doses. The implications for different equivalent doses and ages on the calculation of rates of deformation are also addressed.

  15. Stroke amplifier for deformable mirrors

    PubMed Central

    Webb, Robert H.; Albanese, Marc J.; Zhou, Yaopeng; Bifano, Thomas; Burns, Stephen A.

    2010-01-01

    We demonstrate a simple optical configuration that amplifies the usable stroke of a deformable mirror. By arranging for the wavefront to traverse the deformable mirror more than once, we correct it more than once. The experimental implementation of the idea demonstrates a doubling of 2.0 and 2.04 by two different means. PMID:15495423

  16. Global organization of tectonic deformation on Venus

    NASA Technical Reports Server (NTRS)

    Bilotti, Frank; Connors, Chris; Suppe, John

    1993-01-01

    The geographic organization of surface deformation on Venus as on Earth is a key to understanding the global tectonic system. To date we have mapped the distribution of three unambiguous tectonic land forms on Venus: (1) linear foldbelts analogous to those at plate margins of the Earth; (2) linear rift zones, analogous to continental rifts on the Earth; and (3) distributed plains deformation in the form of wrinkle ridges and extensional faults and fractures. The linear foldbelts are the dominant structural style in the Northern Hemisphere; ninety percent of the planet's foldbelts lie above the equator. In contrast, compressive deformation in the Southern Hemisphere is dominated by two large, sweeping patterns of wrinkle ridges. The two hemispheres are divided by an equatorial region that is largely covered by rift zones and several large tessera blocks. A tectonic model of generally poleward convergence of the Northern Hemisphere explains the distribution of foldbelts and rift zones. In our model, a northern hemispherical plate (or system of plates) moves poleward and deforms along discrete, predominately longitudinal bands. We recognize four types of foldbelts based on their relationships to other large-scale tectonic features on Venus. There are foldbelts that lie within the low plains, foldbelts associated with coronae, novae and chasmata, foldbelts that lie at the margins of poly-deformed tessera plateaus, and the folded mountain belts around Lakshmi Planum. We see a geometric increase in the area of fold belts when normalized to percent area at a given latitude. This increase is consistent with our model of poleward convergence. Also, the orientations of most foldbelts are either approximately north-south or parallel to lines of latitude in the northern hemisphere. This observation is also consistent with the model in that the longitudinal bands are the result of the decreasing area of the sphere as the plate moves poleward and the latitudinal belts are the

  17. Dating of ballpoint pen ink.

    PubMed

    Hofer, R

    2004-11-01

    In this paper we describe a case in which a cash book, dated of the year 2000, was sent to the Forensic Science Division, Document Laboratory, Zurich Canton Police in March 2003. The questioned document was a list of 29 pages containing a consecutive handwritten numbering and dated entries (payments) made of blue ballpoint pen ink. By definition, a cash book has to be written by hand and the entries have to be made daily. The questioned document was suspected to have been written within a short period (e.g., a few hours) and backdated. The document lab was asked to determine the date of the entries of the questioned list. On one hand, we were asked, if the cash book had been kept on account consecutively during the period of one year, and on the other hand, the judges were interested in knowing, if the document could have been written in 2003 and back dated to 2000. To answer these questions, the document was examined for latent elements by electrostatic detection device (ESDA). The relative dating of the entries was performed by the quantification of the ballpoint pen ink dyes and their degradation products using HPLC. Results show that it is possible to determine the relative age of entries written by ballpoint pen within a relatively short time scale, if storage and supporting material of the different samples are the same or at least similar. PMID:15568713

  18. Diatexite Deformation and Magma Extraction on Kangaroo Island, South Australia

    NASA Astrophysics Data System (ADS)

    Hasalova, Pavlina; Weinberg, Roberto; Ward, Lindsay; Fanning, Mark

    2013-04-01

    Migmatite terranes are structurally complex because of strong rheological contrast between layers with different melt contents and because of magma migration leading to volume changes. Migmatite deformation is intimately linked with magma extraction and the origin of granitoids. We investigate here the relationships between an evolving deformation and magma extraction in migmatites formed during the ca. 500Ma Delamerian orogeny, exposed on Kangaroo Island, South Australia. Here, several phases of deformation occurred in the presence of melt. During an early upright, non-cylindrical folding event, magma was channeled towards the hinge zones of antiforms. Funnel-shaped networks of leucosomes form a root zone that link up towards a central axial planar channel, forming the main magma extraction paths during folding. Extraction was associated with fold limb collapse, and antiformal hinge disruption by magma accumulation and transfer. During a later deformation phase, melt-rich diatexites were deformed, and schollen were disaggregated into smaller blocks and schlieren, and deformed into asymmetric, sigmoidal shapes indicative of dextral shearing flow. During flow, magma accumulated preferentially along shear planes, indicating a dilatational component during shearing (transtension) and in strain shadows of schollen. As deformation waned, magma extraction from these diatexites gave rise to N-trending, steeply dipping, funnel-shaped channels not associated to any deformational feature. The funnel-shape of these structures indicates the direction of magma flow. Structures developed during this phase are comparable with those formed during dewatering of soft sediments. Despite a high degree of complexity, magma migration and extraction features record distinct responses to the evolving deformation which can be used to understand deformation, and nature and direction of melt extraction. The oldest and youngest magmatic rocks from migmatites were dated (U-Pb monazite, SHRIMP

  19. [Spectrum research on metamorphic and deformation of tectonically deformed coals].

    PubMed

    Li, Xiao-Shi; Ju, Yi-Wen; Hou, Quan-Lin; Lin, Hong

    2011-08-01

    The structural and compositive evolution of tectonically deformed coals (TDCs) and their influencing factors were investigated and analyzed in detail through Fourier transform infrared spectroscopy (FTIR) and laser Raman spectra analysis. The TDC samples (0.7% < Ro,max <3.1%) were collected from Huaibei coalfield with different deformation mechanisms and intensity. The FTIR of TDCs shows that the metamorphism and the deformation affect the degradation and polycondensation process of macromolecular structure to different degree. The Raman spectra analysis indicates that secondary structure defects can be produced mainly by structural deformation, also the metamorphism influences the secondary structure defects and aromatic structure. Through comprehensive analysis, it was discussed that the ductile deformation could change to strain energy through the increase and accumulation of dislocation in molecular structure units of TDC, and it could make an obvious influence on degradation and polycondensation. While the brittle deformation could change to frictional heat energy and promote the metamorphism and degradation of TDC structure, but has less effect on polycondensation. Furthermore, degradation is the main reason for affecting the structural evolution of coal in lower metamorphic stage, and polycondensation is the most important controlling factor in higher metamorphic stage. Under metamorphism and deformation, the small molecules which break and fall off from the macromolecular tructure of TDC are preferentially replenished and embedded into the secondary structure defects or the residual aromatic rings were formed into aromatic structure by polycondensation. This process improved the stability of coal structure. It is easier for ductile deformation of coal to induce the secondary structure defects than brittle deformation. PMID:22007412

  20. Peer Group Influences on Adolescent Dating Aggression

    ERIC Educational Resources Information Center

    Connolly, Jennifer; Friedlander, Laura

    2009-01-01

    The peer group is a critical social context for dating and romantic relationships. Peer groups provide opportunities to meet potential dating partners and set norms for acceptable dating behaviors. This article explores how peer groups influence dating and dating aggression, as well as how they can be used in prevention efforts. It also reviews…

  1. 21 CFR 1312.25 - Expiration date.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 9 2010-04-01 2010-04-01 false Expiration date. 1312.25 Section 1312.25 Food and... SUBSTANCES Exportation of Controlled Substances § 1312.25 Expiration date. An export permit shall not be valid after the date specified therein, which date shall conform to the expiration date specified in...

  2. 21 CFR 1312.25 - Expiration date.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 9 2013-04-01 2013-04-01 false Expiration date. 1312.25 Section 1312.25 Food and... SUBSTANCES Exportation of Controlled Substances § 1312.25 Expiration date. An export permit shall not be valid after the date specified therein, which date shall conform to the expiration date specified in...

  3. 21 CFR 1312.25 - Expiration date.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 9 2012-04-01 2012-04-01 false Expiration date. 1312.25 Section 1312.25 Food and... SUBSTANCES Exportation of Controlled Substances § 1312.25 Expiration date. An export permit shall not be valid after the date specified therein, which date shall conform to the expiration date specified in...

  4. 21 CFR 1312.25 - Expiration date.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 9 2011-04-01 2011-04-01 false Expiration date. 1312.25 Section 1312.25 Food and... SUBSTANCES Exportation of Controlled Substances § 1312.25 Expiration date. An export permit shall not be valid after the date specified therein, which date shall conform to the expiration date specified in...

  5. 21 CFR 1312.25 - Expiration date.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Expiration date. 1312.25 Section 1312.25 Food and... SUBSTANCES Exportation of Controlled Substances § 1312.25 Expiration date. An export permit shall not be valid after the date specified therein, which date shall conform to the expiration date specified in...

  6. Ruthenium Aluminides: Deformation Mechanisms and Substructure Development

    SciTech Connect

    Tresa M. Pollock

    2005-05-11

    Structural and functional materials that can operate in severe, high temperature environments are key to the operation of a wide range of energy generation systems. Because continued improvements in the energy efficiency of these systems is critical, the need for new materials with higher temperature capabilities is inevitable. Intermetallic compounds, with strong bonding and generally high melting points offer this possibility for a broad array of components such as coatings, electrode materials, actuators and/or structural elements. RuAl is a very unusual intermetallic compound among the large number of B2compounds that have been identified and investigated to date. This material has a very high melting temperature of 2050?C, low thermal expansion, high thermal conductivity and good corrosion resistance. Unlike most other high temperature B2 intermetallics, RuAl possesses good intrinsic deformability at low temperatures. In this program fundamental aspects of low and high temperature mechanical properties and deformation mechanisms in binary and higher order RuAl-based systems have been investigated. Alloying additions of interest included platinum, boron and niobium. Additionally, preliminary studies on high temperature oxidation behavior of these materials have been conducted.

  7. Perceptual transparency from image deformation

    PubMed Central

    Kawabe, Takahiro; Maruya, Kazushi; Nishida, Shin’ya

    2015-01-01

    Human vision has a remarkable ability to perceive two layers at the same retinal locations, a transparent layer in front of a background surface. Critical image cues to perceptual transparency, studied extensively in the past, are changes in luminance or color that could be caused by light absorptions and reflections by the front layer, but such image changes may not be clearly visible when the front layer consists of a pure transparent material such as water. Our daily experiences with transparent materials of this kind suggest that an alternative potential cue of visual transparency is image deformations of a background pattern caused by light refraction. Although previous studies have indicated that these image deformations, at least static ones, play little role in perceptual transparency, here we show that dynamic image deformations of the background pattern, which could be produced by light refraction on a moving liquid’s surface, can produce a vivid impression of a transparent liquid layer without the aid of any other visual cues as to the presence of a transparent layer. Furthermore, a transparent liquid layer perceptually emerges even from a randomly generated dynamic image deformation as long as it is similar to real liquid deformations in its spatiotemporal frequency profile. Our findings indicate that the brain can perceptually infer the presence of “invisible” transparent liquids by analyzing the spatiotemporal structure of dynamic image deformation, for which it uses a relatively simple computation that does not require high-level knowledge about the detailed physics of liquid deformation. PMID:26240313

  8. Opioids and rat erythrocyte deformability.

    PubMed

    Rhoads, D L; Wei, L X; Lin, E T; Rezvani, A; Way, E L

    1986-01-01

    In previous studies from this laboratory, it was noted that opioids in vitro reduced human red blood cell deformability. The effect was found to be dose-dependent, naloxone reversible and preferentially selective kappa ligands exhibited the highest potency. To extend these findings studies were carried out using rat erythrocytes. The time required for erythrocytes to pass through a 5.0 um pore membrane was determined and used as an index of deformability. Opioids added in vitro produced inhibition of deformability in a dose-dependent, naloxone reversible manner. Injecting naive animals with morphine or nalbuphine also produced dose related reductions in red cell deformability. The degree of inhibition produced by nalbuphine correlated well with its plasma concentrations as measured by high performance liquid chromatography (HPLC). Chronic morphine treatment by pellet implantation resulted in the development of tolerance as evidenced by a loss in the ability of morphine in vitro to inhibit red cell deformability. Addition of naloxone resulted in a decrease in filtration time. Thus, the data confirm and extend previous findings on human red blood cells. In as much as previous data from this laboratory demonstrated that opioids inhibit calcium flux from erythrocytes by inhibiting calcium-ATPase and calcium efflux is necessary for normal deformability, it is concluded that opioids act to reduce red cell deformability by inhibition of the calcium pump. PMID:3123933

  9. Perceptual transparency from image deformation.

    PubMed

    Kawabe, Takahiro; Maruya, Kazushi; Nishida, Shin'ya

    2015-08-18

    Human vision has a remarkable ability to perceive two layers at the same retinal locations, a transparent layer in front of a background surface. Critical image cues to perceptual transparency, studied extensively in the past, are changes in luminance or color that could be caused by light absorptions and reflections by the front layer, but such image changes may not be clearly visible when the front layer consists of a pure transparent material such as water. Our daily experiences with transparent materials of this kind suggest that an alternative potential cue of visual transparency is image deformations of a background pattern caused by light refraction. Although previous studies have indicated that these image deformations, at least static ones, play little role in perceptual transparency, here we show that dynamic image deformations of the background pattern, which could be produced by light refraction on a moving liquid's surface, can produce a vivid impression of a transparent liquid layer without the aid of any other visual cues as to the presence of a transparent layer. Furthermore, a transparent liquid layer perceptually emerges even from a randomly generated dynamic image deformation as long as it is similar to real liquid deformations in its spatiotemporal frequency profile. Our findings indicate that the brain can perceptually infer the presence of "invisible" transparent liquids by analyzing the spatiotemporal structure of dynamic image deformation, for which it uses a relatively simple computation that does not require high-level knowledge about the detailed physics of liquid deformation. PMID:26240313

  10. Teen-Age Dating Violence.

    ERIC Educational Resources Information Center

    Kyle, Karla J.

    It has been estimated that one out of three teenage girls will be involved in an abusive relationship or experience violence in their relationships. Given the fact that studies are showing higher incidence of dating violence reported among teenagers, the importance and usefulness of this topic for anyone who works with adolescents cannot be…

  11. Online Dating and Conjugal Bereavement

    ERIC Educational Resources Information Center

    Young, Dannagal Goldthwaite; Caplan, Scott E.

    2010-01-01

    This study examined self-presentation in the online dating profiles of 241 widowed and 280 divorced individuals between 18 and 40 years old. A content analysis of open-ended user-generated profiles assessed the presence or absence of various themes, including the user's marital status, the backstory of their lost relationship, and whether they…

  12. Diatexite Deformation and Magma Extraction on Kangaroo Island, South Australia

    NASA Astrophysics Data System (ADS)

    Hasalova, P.; Weinberg, R. F.; Ward, L.; Fanning, C. M.

    2012-12-01

    Migmatite terranes are structurally complex. We have investigated the relationships between deformation and magma extraction in migmatites formed during the Delamerian orogeny on Kangaroo Island. Several phases of deformation occurred in the presence of melt (D1-D4) and we describe how magma segregation, accumulation and extraction changes with deformation style. During an early upright folding event (D2), magma was channelled towards the hinge of antiforms. Funnel-shaped networks of leucosomes form a root that link towards a central axial planar channel, marking the main magma extraction paths. Extraction was associated with limb collapse, and antiformal hinge disruption. During a later deformation phase (D4), diatexites were sheared so that schollen were disaggregated into smaller blocks and schlieren, and deformed into asymmetric, sigmoidal shapes. Foliations in the magmatic matrix and schollen asymmetry indicate dextral shearing. During flow, magma accumulated in shear planes, indicating a dilational component during shearing (transtension) and on strain shadows of schollen. As deformation waned (post-D4), magma extraction from these diatexites gave rise to steeply dipping, funnel-shaped channels, similar to those developed during folding. The funnel-shape networks are interpreted as magma extraction networks and indicate magma flow direction. Structures developed during this phase are comparable with those developed during dewatering of soft sediments. The magmatic rocks from migmatites formed early, during folding, and formed late after deformation waned were dated. Both have two monazite (U-Pb, SHRIMP) age groups of ~490Ma and ~505-520Ma. The older sample has a well-defined peak at 505-510Ma and trails into the younger ages. The younger sample has the opposite, with few old spots and a well-defined young peak at ~490Ma. The age range indicates the duration of anatexis, and well-defined peaks are interpreted to mark the age of individual magma batch

  13. Metastable vacua and complex deformations

    SciTech Connect

    Tatar, Radu; Wetenhall, Ben

    2007-12-15

    We use the non-normalizable complex deformations to describe the stringy realizations of the metastable vacua in N=1, SU(N{sub c}) SUSY theories with N{sub f}>N{sub c} massive fundamental flavors. The consideration of the non-normalizable deformations requires a modified toric duality. The new approach considers the tachyon condensation between pairs of wrapped D5 branes and anti-D5 branes and the resulting mixing between some cycles in the geometry. We enlarge the class of metastable vacua to the case of branes-antibranes wrapped on cycles of deformed A{sub n} singularities.

  14. Videogrammetric Model Deformation Measurement Technique

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Liu, Tian-Shu

    2001-01-01

    The theory, methods, and applications of the videogrammetric model deformation (VMD) measurement technique used at NASA for wind tunnel testing are presented. The VMD technique, based on non-topographic photogrammetry, can determine static and dynamic aeroelastic deformation and attitude of a wind-tunnel model. Hardware of the system includes a video-rate CCD camera, a computer with an image acquisition frame grabber board, illumination lights, and retroreflective or painted targets on a wind tunnel model. Custom software includes routines for image acquisition, target-tracking/identification, target centroid calculation, camera calibration, and deformation calculations. Applications of the VMD technique at five large NASA wind tunnels are discussed.

  15. Dating Techniques in Archaeology and Paleoanthropology.

    ERIC Educational Resources Information Center

    Taylor, R. E.

    1987-01-01

    Discusses some of the new physical dating methods being used by archaeologists and paleoanthropologists to study the material remains of ancient primates. Describes the quaternary physical dating techniques, advances in radiocarbon dating, and the radiocalcium data method. (TW)

  16. 40 CFR 63.403 - Compliance dates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... compliance date shall be 18 months after September 8, 1994. (b) For new IPCT's that have an initial startup... initial startup on or after September 8, 1994, the compliance date shall be the date of the initial startup....

  17. 40 CFR 63.403 - Compliance dates.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... initial startup before September 8, 1994, the compliance date shall be September 8, 1994. (c) For new IPCT's that have an initial startup on or after September 8, 1994, the compliance date shall be the date of the initial startup....

  18. 40 CFR 63.403 - Compliance dates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... initial startup before September 8, 1994, the compliance date shall be September 8, 1994. (c) For new IPCT's that have an initial startup on or after September 8, 1994, the compliance date shall be the date of the initial startup....

  19. 40 CFR 63.403 - Compliance dates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... initial startup before September 8, 1994, the compliance date shall be September 8, 1994. (c) For new IPCT's that have an initial startup on or after September 8, 1994, the compliance date shall be the date of the initial startup....

  20. Dating techniques in archaeology and paleoanthropology

    SciTech Connect

    Taylor, R.E.

    1987-02-15

    Archaeologists have an increasing array of physical dating methods at their disposal. R.E. Taylor of the University of California discusses available techniques, recent advances in radiocarbon dating, and current developments in radiocalcium dating.

  1. 40 CFR 62.3672 - Effective Date.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Sewage Sludge Incinerators § 62.3672 Effective Date. The Federal effective date of the Indiana State Plan for existing Sewage Sludge Incinerators is August 12, 2013. Effective Date Note: At 78 FR 34920,...

  2. Ice Core Dating Software for Interactive Dating of Ice Cores

    NASA Astrophysics Data System (ADS)

    Kurbatov, A. V.; Mayewski, P. A.; Abdul Jawad, B. S.

    2005-12-01

    Scientists involved in ice core dating are well familiar with the problem of identification and recording the depth of annual signals using stable isotopes, glaciochemistry, ECM (electrical conductivity), DEP (dielectric properties) and particle counter data. Traditionally all parameters used for ice core dating were plotted as a function of depth, printed and after years were marked on the paper, converted to depth vs. age time scale. To expedite this tedious and manual process we developed interactive computer software, Ice core Dating (ICD) program. ICD is written in Java programming language, and uses GPL and GPL site licensed graphic libraries. The same 3.5 Mb in size pre-compiled single jar file, that includes all libraries and application code, was successfully tested on WinOS, Mac OSX, Linux, and Solaris operating systems running Java VM version 1.4. We have followed the modular design philosophy in our source code so potential integration with other software modules, data bases and server side distributed computer environments can be easily implemented. We expect to continue development of new suites of tools for easy integration of ice core data with other available time proxies. ICD is thoroughly documented and comes with a technical reference and cookbook that explains the purpose of the software and its many features, and provides examples to help new users quickly become familiar with the operation and philosophy of the software. ICD is available as a free download from the Climate Change Institute web site ( under the terms of GNU GPL public license.

  3. 31 CFR 536.302 - Effective date.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY NARCOTICS TRAFFICKING SANCTIONS REGULATIONS General... of specially designated narcotics traffickers designated after that date, the earlier of the date...

  4. 31 CFR 536.302 - Effective date.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY NARCOTICS TRAFFICKING SANCTIONS REGULATIONS General... of specially designated narcotics traffickers designated after that date, the earlier of the date...

  5. 31 CFR 536.302 - Effective date.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY NARCOTICS TRAFFICKING SANCTIONS REGULATIONS General... of specially designated narcotics traffickers designated after that date, the earlier of the date...

  6. 31 CFR 536.302 - Effective date.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY NARCOTICS TRAFFICKING SANCTIONS REGULATIONS General... of specially designated narcotics traffickers designated after that date, the earlier of the date...

  7. 31 CFR 536.302 - Effective date.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... FOREIGN ASSETS CONTROL, DEPARTMENT OF THE TREASURY NARCOTICS TRAFFICKING SANCTIONS REGULATIONS General... of specially designated narcotics traffickers designated after that date, the earlier of the date...

  8. Shear deformation in granular materials

    SciTech Connect

    Bardenhagen, S.G.; Brackbill, J.U.; Sulsky, D.L.

    1998-12-31

    An investigation into the properties of granular materials is undertaken via numerical simulation. These simulations highlight that frictional contact, a defining characteristic of dry granular materials, and interfacial debonding, an expected deformation mode in plastic bonded explosives, must be properly modeled. Frictional contact and debonding algorithms have been implemented into FLIP, a particle in cell code, and are described. Frictionless and frictional contact are simulated, with attention paid to energy and momentum conservation. Debonding is simulated, with attention paid to the interfacial debonding speed. A first step toward calculations of shear deformation in plastic bonded explosives is made. Simulations are performed on the scale of the grains where experimental data is difficult to obtain. Two characteristics of deformation are found, namely the intermittent binding of grains when rotation and translation are insufficient to accommodate deformation, and the role of the binder as a lubricant in force chains.

  9. Carrier Deformability in Drug Delivery.

    PubMed

    Morilla, Maria Jose; Romero, Eder Lilia

    2016-01-01

    Deformability is a key property of drug carriers used to increase the mass penetration across the skin without disrupting the lipid barrier. Highly deformable vesicles proved to be more effective than conventional liposomes in delivering drugs into and across the mammalian skin upon topical non occlusive application. In the past five years, highly deformable vesicles have been used for local delivery of drugs on joint diseases, skin cancer, atopic dermatitis, would healing, psoriasis, scar treatment, fungal, bacteria and protozoa infections. Promising topical vaccination strategies rely also in this type of carriers. Here we provide an overview on the main structural and mechanical features of deformable vesicles, to finish with an extensive update on their latest preclinical applications. PMID:26675226

  10. Modelling magnetically deformed neutron stars

    NASA Astrophysics Data System (ADS)

    Haskell, B.; Samuelsson, L.; Glampedakis, K.; Andersson, N.

    2008-03-01

    Rotating deformed neutron stars are important potential sources for ground-based gravitational wave interferometers such as LIGO, GEO600 and VIRGO. One mechanism that may lead to significant non-asymmetries is the internal magnetic field. It is well known that a magnetic star will not be spherical and, if the magnetic axis is not aligned with the spin axis, the deformation will lead to the emission of gravitational waves. The aim of this paper is to develop a formalism that would allow us to model magnetically deformed stars, using both realistic equations of state and field configurations. As a first step, we consider a set of simplified model problems. Focusing on dipolar fields, we determine the internal magnetic field which is consistent with a given neutron star model and calculate the associated deformation. We discuss the relevance of our results for current gravitational wave detectors and future prospects.

  11. Promoting research in rock deformation

    NASA Astrophysics Data System (ADS)

    Kirby, Steve

    In response to informal discussions at the 1988 AGU Spring Meeting in Baltimore, Md., a dinner colloquium was held December 5, 1988, in San Francisco. Our purpose was to explore ways of promoting basic research in rock deformation, for which no professional organization exists that spans the full range of research interests. In spite of an informal distribution of announcements of the meeting, 54 people attended.Rock deformation is the materials science of the crystalline and amorphous materials that make up the solid Earth. As such, it includes not only the physical processes responsible for brittle and ductile deformation but also the important chemical processes that influence time-dependent inelastic deformation. Consequently, there is a continuing need to engage interest and collaboration from materials scientists, mineral physicists, metallurgists, surface chemists, and geochemists in the study of the inelastic mechanical behavior of these complex materials.

  12. ROCK DEFORMATION. Final Progress Report

    SciTech Connect

    2002-05-24

    The Gordon Research Conference (GRC) on ROCK DEFORMATION was held at II Ciocco from 5/19/02 thru 5/24/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  13. M theory on deformed superspace

    NASA Astrophysics Data System (ADS)

    Faizal, Mir

    2011-11-01

    In this paper we will analyze a noncommutative deformation of the Aharony-Bergman-Jafferis-Maldacena (ABJM) theory in N=1 superspace formalism. We will then analyze the Becchi-Rouet-Stora-Tyutin (BRST) and anti-BRST symmetries for this deformed ABJM theory, and its linear as well as nonlinear gauges. We will show that the sum of the gauge fixing term and the ghost term for this deformed ABJM theory can be expressed as a combination of the total BRST and the total anti-BRST variation, in Landau and nonlinear gauges. We will show that in Landau and Curci-Ferrari gauges deformed ABJM theory is invariant under an additional set of symmetry transformations. We will also discuss the effect that the addition of a bare mass term has on this theory.

  14. Variable focal length deformable mirror

    DOEpatents

    Headley, Daniel; Ramsey, Marc; Schwarz, Jens

    2007-06-12

    A variable focal length deformable mirror has an inner ring and an outer ring that simply support and push axially on opposite sides of a mirror plate. The resulting variable clamping force deforms the mirror plate to provide a parabolic mirror shape. The rings are parallel planar sections of a single paraboloid and can provide an on-axis focus, if the rings are circular, or an off-axis focus, if the rings are elliptical. The focal length of the deformable mirror can be varied by changing the variable clamping force. The deformable mirror can generally be used in any application requiring the focusing or defocusing of light, including with both coherent and incoherent light sources.

  15. Deformations in chiral liquid crystals

    NASA Astrophysics Data System (ADS)

    Shibaev, Petr; Reddy, Kathryn; Bateman, Daniel; Iljin, Andrey

    2014-03-01

    Deformations and their relaxation in chiral liquid crystals are studied experimentally and theoretically in planar geometry for liquid crystalline mixtures of varying viscosities. It is shown by both methods that shear deformation in liquid crystals results in the inclination and extension of cholesteric helix in samples with high viscosity. Stretching deformation results in shrinking cholesteric helix. This leads to a possibility of detecting deformations on a nanometer scale by observing changes in selective reflection spectra. Theoretical model takes into account elastic strain of physical network formed by the entanglements between components of liquid crystalline mixture, viscosity of the matrix and elasticity of the liquid crystalline subsystem. This allows to model mechanical response of the matrix with different viscosities to stretching and shear of various amplitudes. It is shown that relaxation of the cholesteric helix takes much shorter time than mechanical relaxation of the mixtures. The model perfectly agrees with experimental data. The model is compared with theoretical model describing behavior of elastomers.

  16. 76 FR 77831 - 2012 Presidential Candidate Matching Fund Submission Dates and Post Date of Ineligibility Dates...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-14

    ... (``DOI''). Candidates are required to submit a NOCO statement prior to each regularly scheduled date on..., and accounts receivable. 11 CFR 9034.5(a). Candidates will be notified of their DOI by the Commission. A Candidate who has net outstanding campaign obligations post-DOI may continue to submit...

  17. Anatomy of gravitationally deformed slopes

    NASA Astrophysics Data System (ADS)

    Chigira, Masahiro; Yamasaki, Shintaro; Hariyama, Takehiro

    2010-05-01

    Deep-seated gravitational slope deformation is the deformation of rocks as well as slope surfaces, but the internal structures have not been well observed and described before. This is mainly due to the difficulty in obtaining undisturbed samples from underground. We analyzed the internal deformational structures of gravitationally deformed slopes by using high quality drilled cores obtained by hybrid drilling technique, which has been recently developed and can recover very fragile materials that could not be taken by the conventional drilling techniques. Investigated slopes were gravitationally deformed out-facing slopes of pelitic schist and shale. The slope surfaces showed deformational features of small steps, depressions, knobs, and linear depressions, but had no major main scarp and landslide body with well-defined outline. This is indicative of slow, deep-seated gravitational deformation. Most of these small deformational features are hidden by vegetations, but they are detected by using airborne laser scanner. Drilled cores showed that the internal deformation is dominated by the slip and tearing off along foliations. Slippage along foliations is conspicuous in pelitic schist: Pelitic schist is sheared, particularly along black layers, which are rich in graphite and pyrite. Graphite is known to be a solid lubricant in material sciences, which seems to be why shearing occurs along the black layers. Rock mass between two slip layers is sheared, rotated, fractured, and pulverized; undulation of bedding or schistosity could be the nucleation points of fracturing. Tearing off along foliations is also the major deformation mode, which forms jagged morphology of rock fragments within shear zones. Rock fragments with jagged surface are commonly observed in "gouge", which is very different from tectonic gouge. This probably reflects the low confining pressures during their formation. Microscopic to mesoscopic openings along fractures are commonly observed with

  18. Measurement of deformations by NMR

    NASA Astrophysics Data System (ADS)

    Bytchenkoff, Dimitri; Rodts, Stéphane

    2015-12-01

    Two NMR data acquisition protocols together with corresponding data processing algorithms for locating macroscopic objects, measuring distances between them or monitoring their displacements or deformations with microscopic precision are presented and discussed. The performance of the methods is demonstrated by applying them to the measurement of deformations of a freely supported beam under loading. We believe that our methods will find their applications in mechanics, civil engineering and medicine.

  19. Mixing of discontinuously deforming media.

    PubMed

    Smith, L D; Rudman, M; Lester, D R; Metcalfe, G

    2016-02-01

    Mixing of materials is fundamental to many natural phenomena and engineering applications. The presence of discontinuous deformations-such as shear banding or wall slip-creates new mechanisms for mixing and transport beyond those predicted by classical dynamical systems theory. Here, we show how a novel mixing mechanism combining stretching with cutting and shuffling yields exponential mixing rates, quantified by a positive Lyapunov exponent, an impossibility for systems with cutting and shuffling alone or bounded systems with stretching alone, and demonstrate it in a fluid flow. While dynamical systems theory provides a framework for understanding mixing in smoothly deforming media, a theory of discontinuous mixing is yet to be fully developed. New methods are needed to systematize, explain, and extrapolate measurements on systems with discontinuous deformations. Here, we investigate "webs" of Lagrangian discontinuities and show that they provide a template for the overall transport dynamics. Considering slip deformations as the asymptotic limit of increasingly localised smooth shear, we also demonstrate exactly how some of the new structures introduced by discontinuous deformations are analogous to structures in smoothly deforming systems. PMID:26931594

  20. Microstructures and deformation mechanisms of experimentally deformed gabbro

    NASA Astrophysics Data System (ADS)

    Zhou, Yongsheng; He, Changrong

    2015-04-01

    The natural gabbro samples were deformed at temperature ranging from 700 to 1150 °C with strain rate steps of 1 × 10-4, 2.5 × 10-5, 6.3 × 10-6 s-1. The mechanical data show that sample experiences gradual transition from semi-brittle flow to plastic flow, corresponding to a systematically decreasing stress exponent n with the increasing temperature ranging from 16.5 to 4.1 (He et al. Sci China (D) 46(7):730-742, 2003). We investigate microstructures and deformation mechanisms of experimentally deformed gabbro under transmission electron microscope in this study. For low temperature of 700 °C to 950 °C, the deformation is mainly accommodated with dislocation glide and mechanical twinning, corresponding to stress exponent lager than 5, which means semi-brittle deformation. Whereas with higher temperature up to 1000 °C-1150 °C, the deformation is accommodated mainly with dislocation glide and climb corresponding to stress exponent of 4.1, which means plastic deformation. Evidence of dislocation climb has been found as dislocation walls in plagioclase. The observed slip system in plagioclase is (001)1/2[110] and that in clinopyroxene are (100)[001] and (010)[001]. The (010)[001] slip system in clinopyroxene is newly found in this work. Melt was found at temperature of 950 °C-1050 °C. The melt glass distributed both in melt thin film between two grain boundaries and melt tubules of triangular along three grain boundaries at temperature of 950 °C-1000 °C. The melt triangular interconnected to the melt film at temperature of 1050 °C-1150 °C, where the melt chemical composition differentiated into iron-rich dark dots and silicate-rich matrix.

  1. Progressive deformation of feldspar recording low-barometry impact processes, Tenoumer impact structure, Mauritania

    NASA Astrophysics Data System (ADS)

    Jaret, Steven J.; Kah, Linda C.; Harris, R. Scott

    2014-06-01

    The Tenoumer impact structure is a small, well-preserved crater within Archean to Paleoproterozoic amphibolite, gneiss, and granite of the Reguibat Shield, north-central Mauritania. The structure is surrounded by a thin ejecta blanket of crystalline blocks (granitic gneiss, granite, and amphibolite) and impact-melt rocks. Evidence of shock metamorphism of quartz, most notably planar deformation features (PDFs), occurs exclusively in granitic clasts entrained within small bodies of polymict, glass-rich breccia. Impact-related deformation features in oligoclase and microcline grains, on the other hand, occur both within clasts in melt-breccia deposits, where they co-occur with quartz PDFs, and also within melt-free crystalline ejecta, in the absence of co-occurring quartz PDFs. Feldspar deformation features include multiple orientations of PDFs, enhanced optical relief of grain components, selective disordering of alternate twins, inclined lamellae within alternate twins, and combinations of these individual textures. The distribution of shock features in quartz and feldspar suggests that deformation textures within feldspar can record a wide range of average pressures, starting below that required for shock deformation of quartz. We suggest that experimental analysis of feldspar behavior, combined with detailed mapping of shock metamorphism of feldspar in natural systems, may provide critical data to constrain energy dissipation within impact regimes that experienced low average shock pressures.

  2. How the eastern Qilian Shan Mountain was deformed, revealed by deformed fluvial terraces

    NASA Astrophysics Data System (ADS)

    Hu, X.; Pan, B.; Gao, H.; Hu, Z.; Geng, H.; Cao, B.

    2012-12-01

    The northwest-southeastern treading Qilian Shan Mountain, margining the northeastern Tibetan Plateau, has been uplifting and deforming related to thrust faults bordering the mountain range in the north. By now, the fault thrust rate and how the mountain was uplifted and deformed is poorly documented along the eastern Qilian Shan. In this study, several flights of late Quaternary fluvial terraces along two rivers (Xiying River and Jinta River), sourced from the mountain crest and flowing transecting these thrust faults and folds, are surveyed by differential GPS with the accuracy of lower than 10 centimeters. Meanwhile, the abandonment times of terrace surfaces were dated by OSL dating on the overlying loess above the fluvial deposits. Analysis results of height data show that fluvial terrace surfaces were obviously deformed related to thrusting and folding. At first, we derive an average uplift rate of 0.05~0.2 mm/yr, which is contributed by folding along the low-mountain range since 120 ka B.P. When the uplift contributed by thrust is added, the total rate of uplift would be 0.45-0.60 mm/yr. The second, by the geometry of terrace surface height, the thrust geometry under the surface is deduced. Along the low-mountain range (with elevation from 2000 m to 3000 m), the dip angle of thrust is bended from ~30° to ~50° at the depth of around 15 km, and at the depth of ~20 km, the thrust dip angle is changed to ~26°. Along the Huangcheng-Taerzhuang Fault, which bordering the high-mountain range (with elevation from 3000 m to 5000 m) and the low-mountain range, the dip angle is bended from ~70° at the surface to ~47° below the depth of ~5 km, and at the depth below 23 km, the dip angel of the thrust is >30°. We conclude that in the late Quaternary, the deforming of mountain range along the eastern Qilian Shan is accomplished both by thrusting and folding; the different uplift rate is mainly caused by different thrust angle in the depth along the eastern Qilian Shan

  3. Perioperative Assessment of Myocardial Deformation

    PubMed Central

    Duncan, Andra E.; Alfirevic, Andrej; Sessler, Daniel I.; Popovic, Zoran B.; Thomas, James D.

    2014-01-01

    Evaluation of left ventricular performance improves risk assessment and guides anesthetic decisions. However, the most common echocardiographic measure of myocardial function, the left ventricular ejection fraction (LVEF), has important limitations. LVEF is limited by subjective interpretation which reduces accuracy and reproducibility, and LVEF assesses global function without characterizing regional myocardial abnormalities. An alternative objective echocardiographic measure of myocardial function is thus needed. Myocardial deformation analysis, which performs quantitative assessment of global and regional myocardial function, may be useful for perioperative care of surgical patients. Myocardial deformation analysis evaluates left ventricular mechanics by quantifying strain and strain rate. Strain describes percent change in myocardial length in the longitudinal (from base to apex) and circumferential (encircling the short-axis of the ventricle) direction and change in thickness in the radial direction. Segmental strain describes regional myocardial function. Strain is a negative number when the ventricle shortens longitudinally or circumferentially and is positive with radial thickening. Reference values for normal longitudinal strain from a recent meta-analysis using transthoracic echocardiography are (mean ± SD) −19.7 ± 0.4%, while radial and circumferential strain are 47.3 ± 1.9 and −23.3 ± 0.7%, respectively. The speed of myocardial deformation is also important and is characterized by strain rate. Longitudinal systolic strain rate in healthy subjects averages −1.10 ± 0.16 sec−1. Assessment of myocardial deformation requires consideration of both strain (change in deformation), which correlates with LVEF, and strain rate (speed of deformation), which correlates with rate of rise of left ventricular pressure (dP/dt). Myocardial deformation analysis also evaluates ventricular relaxation, twist, and untwist, providing new and noninvasive methods to

  4. Analysis of Mining Terrain Deformation Characteristics with Deformation Information System

    NASA Astrophysics Data System (ADS)

    Blachowski, Jan; Milczarek, Wojciech; Grzempowski, Piotr

    2014-05-01

    Mapping and prediction of mining related deformations of the earth surface is an important measure for minimising threat to surface infrastructure, human population, the environment and safety of the mining operation itself arising from underground extraction of useful minerals. The number of methods and techniques used for monitoring and analysis of mining terrain deformations is wide and increasing with the development of geographical information technologies. These include for example: terrestrial geodetic measurements, global positioning systems, remote sensing, spatial interpolation, finite element method modelling, GIS based modelling, geological modelling, empirical modelling using the Knothe theory, artificial neural networks, fuzzy logic calculations and other. The aim of this paper is to introduce the concept of an integrated Deformation Information System (DIS) developed in geographic information systems environment for analysis and modelling of various spatial data related to mining activity and demonstrate its applications for mapping and visualising, as well as identifying possible mining terrain deformation areas with various spatial modelling methods. The DIS concept is based on connected modules that include: the spatial database - the core of the system, the spatial data collection module formed by: terrestrial, satellite and remote sensing measurements of the ground changes, the spatial data mining module for data discovery and extraction, the geological modelling module, the spatial data modeling module with data processing algorithms for spatio-temporal analysis and mapping of mining deformations and their characteristics (e.g. deformation parameters: tilt, curvature and horizontal strain), the multivariate spatial data classification module and the visualization module allowing two-dimensional interactive and static mapping and three-dimensional visualizations of mining ground characteristics. The Systems's functionality has been presented on

  5. Preferred orientation in experimentally deformed stishovite: implications for deformation mechanisms

    NASA Astrophysics Data System (ADS)

    Kaercher, P. M.; Zepeda-Alarcon, E.; Prakapenka, V.; Kanitpanyacharoen, W.; Smith, J.; Sinogeikin, S. V.; Wenk, H. R.

    2014-12-01

    The crystal structure of the high pressure SiO2 polymorph stishovite has been studied in detail, yet little is known about its deformation mechanisms. Information about how stishovite deforms under stress is important for understanding subduction of quartz-bearing crustal rocks into the mantle. Particularly, stishovite is elastically anisotropic and thus development of crystallographic preferred orientation (CPO) during deformation may contribute to seismic anomalies in the mantle. We converted a natural sample of flint to stishovite in a laser heated diamond anvil cell and compressed the stishovite aggregate up to 38 GPa. Diffraction patterns were collected in situ in radial geometry at the Advanced Light Source (ALS) and the Advanced Photon Source (APS) to examine development of CPO during deformation. We find that (001) poles preferentially align with the compression direction and infer deformation mechanisms leading to the observed CPO with visco-plastic self consistent (VPSC) polycrystal plasticity models. Our results show pyramidal and basal slip are most likely active at high pressure and ambient temperature, in agreement with transmission electron microscopy (TEM) studies of rutile (TiO2) and paratellurite (TeO2), which are isostructural to stishovite. Conversely other TEM studies of stishovite done at higher temperature suggest dominant prismatic slip. This indicates that a variety of slip systems may be active in stishovite, depending on conditions. As a result, stishovite's contribution to the seismic signature in the mantle may vary as a function of pressure and temperature and thus depth.

  6. Mobility of iridium in terrestrial environments: Implications for the interpretation of impact-related mass-extinctions

    NASA Astrophysics Data System (ADS)

    Martín-Peinado, F. J.; Rodríguez-Tovar, F. J.

    2010-08-01

    Traditionally, iridium has been considered an element of low mobility, but its behavior is still debated. Ir concentration in a soil affected by a catastrophic mining spill in 1998 that covered the soil with a layer of tailings offers the opportunity to analyse an exceptional Ir-bearing horizon 10 years after deposition. This has enabled comparisons with the values of past Ir-bearing horizons associated to impact-related mass-extinction events. Iridium concentration in the tailings (0.349 ppm) was 5-fold higher than the anomaly in the K-Pg at The Moody Creek Mine section (the highest values obtained from terrestrial sections). The oxidative weathering of the tailings caused the release of Ir and infiltration into the soil. Iridium distribution in depth indicates redistribution throughout the profile in relation to the change in the physico-chemical properties of the soil. With regard to the background concentration in the soil (0.056 ppm), anomalous values of Ir (0.129 ppm) can be detected to 11 cm below the layer of tailings. The correlation analysis between the Ir concentration and the main properties and constituents of the soils indicated a significant correlation with sulfur, iron, clay content, and pH. Selective extractions were made to study the forms in which Ir can be mobilized in the soil. The residual/insoluble fraction was >90% of the total Ir concentration in soil. Soluble-in-water concentration of Ir (1.5% of total) was detected in the uppermost 2-3 cm of the soil, which were directly affected by the leaching of acidic waters coming from the oxidation of the pyrite tailings. Iridium retention in the affected part of the soil reached 9% of the total Ir concentration; this retention could be related to the amorphous iron forms dissolved by the oxalic-oxalate extraction. However, according to our research, original Ir abundance could be secondarily modified, and then a direct analysis of the iridium values recorded in sediments could induce

  7. School Counselors' Role in Dating Violence Intervention

    ERIC Educational Resources Information Center

    Craigen, Laurie M.; Sikes, April; Healey, Amanda; Hays, Danica

    2009-01-01

    Dating violence among adolescents is a major public health concern. The purpose of this paper is to examine five factors of which school counselors must be aware in order to recognize, intervene, and report incidence of dating violence. These factors are (a) understanding the diverse definitions of dating violence, (b) recognizing dating violence…

  8. 7 CFR 987.12 - Marketable dates.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... RIVERSIDE COUNTY, CALIFORNIA Order Regulating Handling Definitions § 987.12 Marketable dates. Marketable... exeption of Canada. The Committee may establish different requirements for different countries. (d) Product dates. Product dates are marketable dates that are inspected and certified as meeting the...

  9. 38 CFR 21.9635 - Discontinuance dates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... individual is enrolled in an institution of higher learning on the date of expiration of his or her period of... Discontinuance dates. The effective date of a reduction or discontinuance of educational assistance will be as... payment, the discontinuance date of educational assistance for the purpose of that lump sum payment...

  10. 38 CFR 21.7135 - Discontinuance dates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ...) Eligibility expires. If the veteran is pursuing a course on the date of expiration of eligibility as... Bill-Active Duty) Payments-Educational Assistance § 21.7135 Discontinuance dates. The effective date of... dependent. If more than one type of reduction or discontinuance is involved, the earliest date will...

  11. 38 CFR 21.7135 - Discontinuance dates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...) Eligibility expires. If the veteran is pursuing a course on the date of expiration of eligibility as... Bill-Active Duty) Payments-Educational Assistance § 21.7135 Discontinuance dates. The effective date of... dependent. If more than one type of reduction or discontinuance is involved, the earliest date will...

  12. 38 CFR 21.3332 - Discontinuance dates.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... expiration of the eligible person's entitlement. (e) Date of interruption of course as determined by the... special training allowance as provided in this section on the earliest date of the following: (a) The ending date of the course. (b) The ending date of the period of enrollment as certified by the...

  13. 38 CFR 21.3332 - Discontinuance dates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... expiration of the eligible person's entitlement. (e) Date of interruption of course as determined by the... special training allowance as provided in this section on the earliest date of the following: (a) The ending date of the course. (b) The ending date of the period of enrollment as certified by the...

  14. 38 CFR 21.3332 - Discontinuance dates.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... expiration of the eligible person's entitlement. (e) Date of interruption of course as determined by the... special training allowance as provided in this section on the earliest date of the following: (a) The ending date of the course. (b) The ending date of the period of enrollment as certified by the...

  15. 40 CFR 75.4 - Compliance dates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of this chapter, the expiration date of a combustion source's opt-in permit under § 74.14(e) of this... become applicable upon the issuance date of the Acid Rain permit. For combustion sources seeking to enter... following dates: (i) January 1, 1995; or (ii) 90 days after the issuance date of the Acid Rain permit...

  16. 38 CFR 21.7135 - Discontinuance dates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ...) Eligibility expires. If the veteran is pursuing a course on the date of expiration of eligibility as... Bill-Active Duty) Payments-Educational Assistance § 21.7135 Discontinuance dates. The effective date of... dependent. If more than one type of reduction or discontinuance is involved, the earliest date will...

  17. 38 CFR 21.9635 - Discontinuance dates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... individual is enrolled in an institution of higher learning on the date of expiration of his or her period of... Discontinuance dates. The effective date of a reduction or discontinuance of educational assistance will be as... payment, the discontinuance date of educational assistance for the purpose of that lump sum payment...

  18. 40 CFR 75.4 - Compliance dates.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... of this chapter, the expiration date of a combustion source's opt-in permit under § 74.14(e) of this... become applicable upon the issuance date of the Acid Rain permit. For combustion sources seeking to enter... following dates: (i) January 1, 1995; or (ii) 90 days after the issuance date of the Acid Rain permit...

  19. 38 CFR 21.9635 - Discontinuance dates.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... individual is enrolled in an institution of higher learning on the date of expiration of his or her period of... Discontinuance dates. The effective date of a reduction or discontinuance of educational assistance will be as... payment, the discontinuance date of educational assistance for the purpose of that lump sum payment...

  20. 38 CFR 21.3332 - Discontinuance dates.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... expiration of the eligible person's entitlement. (e) Date of interruption of course as determined by the... special training allowance as provided in this section on the earliest date of the following: (a) The ending date of the course. (b) The ending date of the period of enrollment as certified by the...

  1. Residual deformations in ocular tissues

    PubMed Central

    Wang, Ruoya; Raykin, Julia; Gleason, Rudolph L.; Ethier, C. Ross

    2015-01-01

    Residual deformations strongly influence the local biomechanical environment in a number of connective tissues. The sclera is known to be biomechanically important in healthy and diseased eyes, such as in glaucoma. Here, we study the residual deformations of the sclera, as well as the adjacent choroid and retina. Using freshly harvested porcine eyes, we developed two approaches of quantifying residual deformations in the spherically shaped tissues of interest. The first consisted of punching discs from the posterior wall of the eye and quantifying the changes in the area and eccentricity of these samples. The second consisted of cutting a ring from the equatorial sclera and making stress-relieving cuts in it. Measurements of curvature were made before and after the stress-relieving cuts. Using the first approach, we observed a 42% areal contraction of the choroid, but only modest contractions of the sclera and retina. The observed contractions were asymmetric. In the second approach, we observed an opening of the scleral rings (approx. 10% decrease in curvature). We conclude that residual bending deformations are present in the sclera, which we speculate may be due to radially heterogeneous growth and remodelling of the tissue during normal development. Further, residual areal deformations present in the choroid may be due to the network of elastic fibres in this tissue and residual deformations in the constituent vascular bed. Future studies of ocular biomechanics should attempt to include effects of these residual deformations into mechanical models in order to gain a better understanding of the biomechanics of the ocular wall. PMID:25740853

  2. Deformation bands evolving to fluid barriers through grain reorganization and fracturing in combination with diagenetic alteration

    NASA Astrophysics Data System (ADS)

    Lommatzsch, M.; Exner, U.; Gier, S.

    2013-12-01

    a preferred fracturing of sericited albite grains and a decomposition of biotite through chemical alteration and mechanical deformation. These mechanisms reduce the mean grain size, increase the amount of phyllosilicates in the matrix and facilitate later growth of authigenic clay minerals. Our findings indicate that the dominant deformation mechanisms and the influence on fluid flow are controlled by the initial mica content, mean grain size and intensity of diagenetic alteration. We identified different evolutionary stages from a high-porosity host rock to a dense deformation band cluster. The measured reduction in porosity by up to 29% is associated with a permeability reduction, reflected in the retention of fluids along band clusters and between conjugated sets of deformation bands. The composition, color and shape of various structures in the outcrop suggest different diagenetic processes and episodes of fluid flow. We identified several reducing and oxidizing fluids which pre- and post-date the deformation band formation.

  3. Deformation of second and third quantization

    NASA Astrophysics Data System (ADS)

    Faizal, Mir

    2015-03-01

    In this paper, we will deform the second and third quantized theories by deforming the canonical commutation relations in such a way that they become consistent with the generalized uncertainty principle. Thus, we will first deform the second quantized commutator and obtain a deformed version of the Wheeler-DeWitt equation. Then we will further deform the third quantized theory by deforming the third quantized canonical commutation relation. This way we will obtain a deformed version of the third quantized theory for the multiverse.

  4. Quality of Life Impact Related to Foot Health in a Sample of Older People with Hallux Valgus.

    PubMed

    López, Daniel López; Callejo González, Lucía; Losa Iglesias, Marta Elena; Canosa, Jesús Luis Saleta; Sanz, David Rodríguez; Lobo, Cesar Calvo; Becerro de Bengoa Vallejo, Ricardo

    2016-01-01

    Hallux Valgus (HV) is a highly prevalent forefoot deformity in older people associated with progressive subluxation and osteoarthritis of the first metatarsophalangeal (MTP) joint and it is believed to be associated with varying degrees of HV effect on the quality of life related to foot health. The aim of this study is to compare the impact of varying degrees of HV on foot health in a sample of older people. The sample consisted of 115 participants, mean age 76.7 ± 9.1, who attended an outpatient center where self-report data were recorded. The degree of HV deformity was determined in both feet using the Manchester Scale (MS) from stage 1 (mild) to 4 (very severe). Scores obtained on the Foot Health Status Questionnaire (FHSQ) were compared. This has 13 questions that assess 4 health domains of the feet, namely pain, function, general health and footwear. The stage 4 of HV shown lower scores for the footwear domain (11.23 ± 15.6); general foot health (27.62 ± 19.1); foot pain (44.65 ± 24.5); foot function (53.04 ± 27.2); vigour (42.19 ± 16.8); social capacity (44.46 ± 28.1); and general health (41.15 ± 25.5) compared with stage 1 of HV (P<0.05) and there were no differences of physical activity (62.81 ± 24.6). Often, quality of life decreases in the elderly population based in large part on their foot health. There is a progressive reduction in health in general and foot health with increasing severity of hallux valgus deformity which appears to be associated with the presence of greater degree of HV, regardless of gender. PMID:26816663

  5. Quality of Life Impact Related to Foot Health in a Sample of Older People with Hallux Valgus

    PubMed Central

    López, Daniel López; Callejo González, Lucía; Iglesias, Marta Elena Losa; Canosa, Jesús Luis Saleta; Sanz, David Rodríguez; Lobo, Cesar Calvo; de Bengoa Vallejo, Ricardo Becerro

    2016-01-01

    Hallux Valgus (HV) is a highly prevalent forefoot deformity in older people associated with progressive subluxation and osteoarthritis of the first metatarsophalangeal (MTP) joint and it is believed to be associated with varying degrees of HV effect on the quality of life related to foot health. The aim of this study is to compare the impact of varying degrees of HV on foot health in a sample of older people. The sample consisted of 115 participants, mean age 76.7 ± 9.1, who attended an outpatient center where self-report data were recorded. The degree of HV deformity was determined in both feet using the Manchester Scale (MS) from stage 1 (mild) to 4 (very severe). Scores obtained on the Foot Health Status Questionnaire (FHSQ) were compared. This has 13 questions that assess 4 health domains of the feet, namely pain, function, general health and footwear. The stage 4 of HV shown lower scores for the footwear domain (11.23 ± 15.6); general foot health (27.62 ± 19.1); foot pain (44.65 ± 24.5); foot function (53.04 ± 27.2); vigour (42.19 ± 16.8); social capacity (44.46 ± 28.1); and general health (41.15 ± 25.5) compared with stage 1 of HV (P<0.05) and there were no differences of physical activity (62.81 ± 24.6). Often, quality of life decreases in the elderly population based in large part on their foot health. There is a progressive reduction in health in general and foot health with increasing severity of hallux valgus deformity which appears to be associated with the presence of greater degree of HV, regardless of gender. PMID:26816663

  6. Radioactive dating of the elements

    NASA Technical Reports Server (NTRS)

    Cowan, John J.; Thielemann, Friedrich-Karl; Truran, James W.

    1991-01-01

    The extent to which an accurate determination of the age of the Galaxy, and thus a lower bound on the age of the universe, can be obtained from radioactive dating is discussed. Emphasis is given to the use of the long-lived radioactive nuclei Re-187, Th-232, U-238, and U-235. The nature of the production sites of these and other potential Galactic chronometers is examined along with their production ratios. Age determinations from models of nucleocosmochronology are reviewed and compared with age determination from stellar sources and age constraints form cosmological considerations.

  7. Birthday and date of death.

    PubMed Central

    Angermeyer, M C; Kühn, L; Osterwald, P

    1987-01-01

    The relation between birthday and date of death has so far been studied from two different perspectives: birthdays were either conceived of as emotionally invested deadlines motivating people to ward off their death which causes a 'dip' in death rates before their birthday, or they were considered as stressful events leading to an increase of mortality on or after their birthday. Using a collection of biographies of famous people from the whole world and another of well-known Swiss citizens we tested hypotheses derived from these assumptions. Neither the 'death-dip' hypotheses nor the 'birthday stress' hypothesis was supported by our results. PMID:3655631

  8. Cretaceous Magmatism and Deformation in Central-west Tibet

    NASA Astrophysics Data System (ADS)

    Arnaud, N. O.; Paquette, J. L.; Leloup, P. H.; Valli, F.; Guillot, S.; Li, H.; Xu, Z.; Lacassin, R.; Tapponnier, P.

    2003-04-01

    While post-jurassic magmatism metamorphism and deformation are widespread in the Himalaya and is also reported along narrow belts along the northern edge of Tibet and further north, they are scarce on the Tibetan Plateau. In western Tibet, the Longmu lake is limited to the south by a significant relief marking a range of magmatic and metamorphic rocks, and bordered by the active left-lateral Goza fault. The range exposes essentially early Mesozoic rocks probably the remnants of a Triassic suture. The highest summits along the Longmu lake are composed of two mica leucocratic granites intruding unprecisely dated Cretaceous sediments (Red Beds). Those granites are locally strongly sheared, although those facies were not found in place. Where observed in the granites this deformation was partly strike slip although less intense, with a subvertical foliation striking N90-110, parallel to the Goza fault. The U/Pb age of the granites indicates a late cretaceous intrusion. 40Ar/39Ar dating yields mica cooling ages of 102 Ma close to the emplacement age both in the undeformed and the deformed facies and thus indicate that deformation was acquired during or very shortly after emplacement: those granites are therefore partly syn-tectonic. Modeling of K-feldspars 40Ar/39Ar ages show rapid cooling just after emplacement, followed by a period of protracted cooling and finally much faster cooling at ca 55 Ma. The discovery of a phase of Cretaceous magmatism and deformation in central Tibet suggests a localized event of probably crustal melting associated with deformation of the same age. Strike slip movements of Cretaceous age have already been reported in a metamorphic corridor locally bordering the present day traces of Altyn Tagh and Kunlun faults (ARNAUD et al., 2003). The discovery of similar facies in central Tibet suggests that this event must be extended further south into Tibet and could therefore has a wider significance than previously thought. The fact that the Goza

  9. Quantifying torso deformity in scoliosis

    NASA Astrophysics Data System (ADS)

    Ajemba, Peter O.; Kumar, Anish; Durdle, Nelson G.; Raso, V. James

    2006-03-01

    Scoliosis affects the alignment of the spine and the shape of the torso. Most scoliosis patients and their families are more concerned about the effect of scoliosis on the torso than its effect on the spine. There is a need to develop robust techniques for quantifying torso deformity based on full torso scans. In this paper, deformation indices obtained from orthogonal maps of full torso scans are used to quantify torso deformity in scoliosis. 'Orthogonal maps' are obtained by applying orthogonal transforms to 3D surface maps. (An 'orthogonal transform' maps a cylindrical coordinate system to a Cartesian coordinate system.) The technique was tested on 361 deformed computer models of the human torso and on 22 scans of volunteers (8 normal and 14 scoliosis). Deformation indices from the orthogonal maps correctly classified up to 95% of the volunteers with a specificity of 1.00 and a sensitivity of 0.91. In addition to classifying scoliosis, the system gives a visual representation of the entire torso in one view and is viable for use in a clinical environment for managing scoliosis.

  10. Mixing of discontinuously deforming media

    NASA Astrophysics Data System (ADS)

    Smith, L. D.; Rudman, M.; Lester, D. R.; Metcalfe, G.

    2016-02-01

    Mixing of materials is fundamental to many natural phenomena and engineering applications. The presence of discontinuous deformations—such as shear banding or wall slip—creates new mechanisms for mixing and transport beyond those predicted by classical dynamical systems theory. Here, we show how a novel mixing mechanism combining stretching with cutting and shuffling yields exponential mixing rates, quantified by a positive Lyapunov exponent, an impossibility for systems with cutting and shuffling alone or bounded systems with stretching alone, and demonstrate it in a fluid flow. While dynamical systems theory provides a framework for understanding mixing in smoothly deforming media, a theory of discontinuous mixing is yet to be fully developed. New methods are needed to systematize, explain, and extrapolate measurements on systems with discontinuous deformations. Here, we investigate "webs" of Lagrangian discontinuities and show that they provide a template for the overall transport dynamics. Considering slip deformations as the asymptotic limit of increasingly localised smooth shear, we also demonstrate exactly how some of the new structures introduced by discontinuous deformations are analogous to structures in smoothly deforming systems.

  11. Transverse deformations of extreme horizons

    NASA Astrophysics Data System (ADS)

    Li, Carmen; Lucietti, James

    2016-04-01

    We consider the inverse problem of determining all extreme black hole solutions to the Einstein equations with a prescribed near-horizon geometry. We investigate this problem by considering infinitesimal deformations of the near-horizon geometry along transverse null geodesics. We show that, up to a gauge transformation, the linearised Einstein equations reduce to an elliptic PDE for the extrinsic curvature of a cross-section of the horizon. We deduce that for a given near-horizon geometry there exists a finite dimensional moduli space of infinitesimal transverse deformations. We then establish a uniqueness theorem for transverse deformations of the extreme Kerr horizon. In particular, we prove that the only smooth axisymmetric transverse deformation of the near-horizon geometry of extreme Kerr, such that cross-sections of the horizon are marginally trapped surfaces, corresponds to that of the extreme Kerr black hole. Furthermore, we determine all smooth and biaxisymmetric transverse deformations of the near-horizon geometry of the five-dimensional extreme Myers-Perry black hole with equal angular momenta. We find a three parameter family of solutions such that cross-sections of the horizon are marginally trapped, which is more general than the known black hole solutions. We discuss the possibility that they correspond to new five-dimensional vacuum black holes.

  12. Deformation T-Cup: a new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa.

    PubMed

    Hunt, Simon A; Weidner, Donald J; McCormack, Richard J; Whitaker, Matthew L; Bailey, Edward; Li, Li; Vaughan, Michael T; Dobson, David P

    2014-08-01

    A new multi-anvil deformation apparatus, based on the widely used 6-8 split-cylinder, geometry, has been developed which is capable of deformation experiments at pressures in excess of 18 GPa at room temperature. In 6-8 (Kawai-type) devices eight cubic anvils are used to compress the sample assembly. In our new apparatus two of the eight cubes which sit along the split-cylinder axis have been replaced by hexagonal cross section anvils. Combining these anvils hexagonal-anvils with secondary differential actuators incorporated into the load frame, for the first time, enables the 6-8 multi-anvil apparatus to be used for controlled strain-rate deformation experiments to high strains. Testing of the design, both with and without synchrotron-X-rays, has demonstrated the Deformation T-Cup (DT-Cup) is capable of deforming 1-2 mm long samples to over 55% strain at high temperatures and pressures. To date the apparatus has been calibrated to, and deformed at, 18.8 GPa and deformation experiments performed in conjunction with synchrotron X-rays at confining pressures up to 10 GPa at 800 °C . PMID:25173308

  13. Deformation T-Cup: A new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa

    NASA Astrophysics Data System (ADS)

    Hunt, Simon A.; Weidner, Donald J.; McCormack, Richard J.; Whitaker, Matthew L.; Bailey, Edward; Li, Li; Vaughan, Michael T.; Dobson, David P.

    2014-08-01

    A new multi-anvil deformation apparatus, based on the widely used 6-8 split-cylinder, geometry, has been developed which is capable of deformation experiments at pressures in excess of 18 GPa at room temperature. In 6-8 (Kawai-type) devices eight cubic anvils are used to compress the sample assembly. In our new apparatus two of the eight cubes which sit along the split-cylinder axis have been replaced by hexagonal cross section anvils. Combining these anvils hexagonal-anvils with secondary differential actuators incorporated into the load frame, for the first time, enables the 6-8 multi-anvil apparatus to be used for controlled strain-rate deformation experiments to high strains. Testing of the design, both with and without synchrotron-X-rays, has demonstrated the Deformation T-Cup (DT-Cup) is capable of deforming 1-2 mm long samples to over 55% strain at high temperatures and pressures. To date the apparatus has been calibrated to, and deformed at, 18.8 GPa and deformation experiments performed in conjunction with synchrotron X-rays at confining pressures up to 10 GPa at 800 °C .

  14. Deformation T-Cup: A new multi-anvil apparatus for controlled strain-rate deformation experiments at pressures above 18 GPa

    SciTech Connect

    Hunt, Simon A. McCormack, Richard J.; Bailey, Edward; Dobson, David P.; Weidner, Donald J.; Whitaker, Matthew L.; Li, Li; Vaughan, Michael T.

    2014-08-15

    A new multi-anvil deformation apparatus, based on the widely used 6-8 split-cylinder, geometry, has been developed which is capable of deformation experiments at pressures in excess of 18 GPa at room temperature. In 6-8 (Kawai-type) devices eight cubic anvils are used to compress the sample assembly. In our new apparatus two of the eight cubes which sit along the split-cylinder axis have been replaced by hexagonal cross section anvils. Combining these anvils hexagonal-anvils with secondary differential actuators incorporated into the load frame, for the first time, enables the 6-8 multi-anvil apparatus to be used for controlled strain-rate deformation experiments to high strains. Testing of the design, both with and without synchrotron-X-rays, has demonstrated the Deformation T-Cup (DT-Cup) is capable of deforming 1–2 mm long samples to over 55% strain at high temperatures and pressures. To date the apparatus has been calibrated to, and deformed at, 18.8 GPa and deformation experiments performed in conjunction with synchrotron X-rays at confining pressures up to 10 GPa at 800 °C.

  15. Vision System for Remote Strain/Deformation Measurement

    SciTech Connect

    Hovis, G.L.

    1999-01-26

    Machine vision metrology is ideally suited to the task of non-contact/non-intrusive deformation and strain measurement in a remote system. The objective of this work-in-progress is to develop a compact instrument for strain measurement consisting of a camera, image capture card, PC, software, and light source. The instrument is portable and useful in a variety of applications and environments. A digital camera with a microscopic lens is connected to an image capture card in a PC. Commercially available image processing software is used to control the image capture and image processing steps leading up to displacement/strain measurement. Image processing steps include filtering and edge/feature enhancement. Custom software is required to control/automate certain elements of the acquisition and processing. Images of a region on the surface of a specimen are acquired at hold points (during static tests) or at regular time intervals (during transients). Salient features in the image scene (microstructure, oxide deposits, etc.) are observed in subsequent images. The strain measurement algorithm characterizes relative motion of the salient features with individual displacement vectors yielding 2-D deformation equations. The set of deformation equations is solved simultaneously to yield unknown deformation gradient terms that are used to express 2-D strain. The overall concept, theory, and test results to date are presented herein.

  16. Constitutive Law and Flow Mechanism in Diamond Deformation

    DOE PAGESBeta

    Yu, Xiaohui; Raterron, Paul; Zhang, Jianzhong; Lin, Zhijun; Wang, Liping; Zhao, Yusheng

    2012-11-19

    Constitutive laws and crystal plasticity in diamond deformation have been the subjects of substantial interest since synthetic diamond was made in 1950's. To date, however, little is known quantitatively regarding its brittle-ductile properties and yield strength at high temperatures. In this paper, we report, for the first time, the strain-stress constitutive relations and experimental demonstration of deformation mechanisms under confined high pressure. The deformation at room temperature is essentially brittle, cataclastic, and mostly accommodated by fracturing on {111} plane with no plastic yielding at uniaxial strains up to 15%. At elevated temperatures of 1000°C and 1200°C diamond crystals exhibit significantmore » ductile flow with corresponding yield strength of 7.9 and 6.3 GPa, indicating that diamond starts to weaken when temperature is over 1000°C. Finally, at high temperature the plastic deformation and ductile flow is meditated by the <110>{111} dislocation glide and a very active {111} micro-twinning.« less

  17. Constitutive Law and Flow Mechanism in Diamond Deformation

    SciTech Connect

    Yu, Xiaohui; Raterron, Paul; Zhang, Jianzhong; Lin, Zhijun; Wang, Liping; Zhao, Yusheng

    2012-11-19

    Constitutive laws and crystal plasticity in diamond deformation have been the subjects of substantial interest since synthetic diamond was made in 1950's. To date, however, little is known quantitatively regarding its brittle-ductile properties and yield strength at high temperatures. In this paper, we report, for the first time, the strain-stress constitutive relations and experimental demonstration of deformation mechanisms under confined high pressure. The deformation at room temperature is essentially brittle, cataclastic, and mostly accommodated by fracturing on {111} plane with no plastic yielding at uniaxial strains up to 15%. At elevated temperatures of 1000°C and 1200°C diamond crystals exhibit significant ductile flow with corresponding yield strength of 7.9 and 6.3 GPa, indicating that diamond starts to weaken when temperature is over 1000°C. Finally, at high temperature the plastic deformation and ductile flow is meditated by the <110>{111} dislocation glide and a very active {111} micro-twinning.

  18. Constitutive Law and Flow Mechanism in Diamond Deformation

    PubMed Central

    Yu, Xiaohui; Raterron, Paul; Zhang, Jianzhong; Lin, Zhijun; Wang, Liping; Zhao, Yusheng

    2012-01-01

    Constitutive laws and crystal plasticity in diamond deformation have been the subjects of substantial interest since synthetic diamond was made in 1950's. To date, however, little is known quantitatively regarding its brittle-ductile properties and yield strength at high temperatures. Here we report, for the first time, the strain-stress constitutive relations and experimental demonstration of deformation mechanisms under confined high pressure. The deformation at room temperature is essentially brittle, cataclastic, and mostly accommodated by fracturing on {111} plane with no plastic yielding at uniaxial strains up to 15%. At elevated temperatures of 1000°C and 1200°C diamond crystals exhibit significant ductile flow with corresponding yield strength of 7.9 and 6.3 GPa, indicating that diamond starts to weaken when temperature is over 1000°C. At high temperature the plastic deformation and ductile flow is meditated by the <110>{111} dislocation glide and a very active {111} micro-twinning. PMID:23166859

  19. Finite Deformation of Magnetoelastic Film

    SciTech Connect

    Barham, Matthew Ian

    2011-05-31

    A nonlinear two-dimensional theory is developed for thin magnetoelastic lms capable of large deformations. This is derived directly from three-dimensional theory. Signi cant simpli cations emerge in the descent from three dimensions to two, permitting the self eld generated by the body to be computed a posteriori. The model is specialized to isotropic elastomers with two material models. First weak magnetization is investigated leading to a free energy where magnetization and deformation are un-coupled. The second closely couples the magnetization and deformation. Numerical solutions are obtained to equilibrium boundary-value problems in which the membrane is subjected to lateral pressure and an applied magnetic eld. An instability is inferred and investigated for the weak magnetization material model.

  20. Deformation processes in forging ceramics

    NASA Technical Reports Server (NTRS)

    Cannon, R. M.; Rhodes, W. H.

    1973-01-01

    The deformation processes involved in the forging of refractory ceramic oxides were investigated. A combination of mechanical testing and forging was utilized to investigate both the flow and fracture processes involved. Deformation studies of very fine grain Al203 revealed an apparent transition in behavior, characterized by a shift in the strain rate sensitivity from 0.5 at low stresses to near unity at higher stresses. The behavior is indicative of a shift in control between two dependent mechanisms, one of which is indicated to be cation limited diffusional creep with significant boundary enhancement. The possible contributions of slip, indicated by crystallographic texture, interface control of the diffusional creep and inhomogeneous boundary sliding are also discussed. Additional experiments indicated an independence of deformation behavior on MgO doping and retained hot pressing impurities, at least for ultrafine grained material, and also an independence of test atmosphere.

  1. Shock metamorphism of deformed quartz

    NASA Technical Reports Server (NTRS)

    Gratz, Andrew J.; Christie, John; Tyburczy, James; Ahrens, Thomas; Pongratz, Peter

    1988-01-01

    The effect produced by shock loading (to peak pressures of 12 and 24) on deformed synthetic quartz containing a dislocation and abundant bubbles and small inclusions was investigated, and the relationships between preexisting dislocation density shock lamellae in the target material were examined. The resultant material was found to be inhomogeneously deformed and extremely fractured. Results of TEM examinations indicate that no change in dislocation density was caused by shock loading except in regions containing shock lamellae, where the dislocation density was lowered. The shock-induced defects tend to nucleate on and be controlled by preexisting stress concentrators; shock lamellae, glassy veins, and most curviplanar defects form in tension, presumably during release. An extremely mobile silica fluid is formed and injected into fractures during release, which forcibly removes crystalline fragments from vein walls. It is concluded that shock deformation in quartz is dominated by fracture and melting.

  2. Chaetal deformities in aquatic oligochaeta

    SciTech Connect

    Brinkhurst, R.O.; Wetzel, M.J.

    1994-12-31

    Gross deformities in the chaetae of specimens of the tubificid Potamothrix hammoniensis were described by Milbrink from Lake Vaenern, Sweden. This lake is one of the most mercury-polluted major lakes of the world. Statistical tests showed a highly significant correlation between the incidence of deformities and the mercury concentration in the sediments. Changes in the pulp and paper mill process led to marked reduction in specimens with deformities. Similarly modified specimens of various species have been observed at a number of sites contaminated with heavy metals or oil residues in North America. Experimental work on chaetal form has demonstrated changes due to conductivity which have also been observed in saline inland waters. These experiments suggest that chaetae may be shed and replaced by worms every few days. EDX observation of chaetae indicated that metals may accumulate in them, and so provide a potential depuration mechanism. Independent physiological studies suggest that worms may be capable of regulating their metal levels.

  3. Microstructure of deformed graywacke sandstones

    SciTech Connect

    Dengler, L.A.

    1980-03-05

    Microsctures in low-permeability graywacke sandstones were studied by optical and scanning electron microscopy (SEM). SEM specimens were prepared by ion-bombardment of thick polished samples. The undeformed rock contains grains in a matrix composed primarily of authigenic chlorite and kaolinite. Chlorite platelets are randomly arranged in face-to-edge relation to one another. Kaolinite occurs as pseudohexagonal crystals stacked face-to-face in pore filling books. Uniaxial-stress experiments covered a range of confining pressures from .1 to 600 MPa. Below 50 MPa confining pressure, intergranular fracturing occurs within the fault zone and near the sample's cylindrical surface. Between 100 and 300 MPa confining pressure, fault zones contain highly fractured grains, gauge and slickensides on grain surfaces. At 600 MPa, the sample contains a diffuse shear zone of highly fractured grains and no well-defined fault. In all samples, the distribution of microcracks is heterogeneous. Different clay minerals exhibit different modes of deformation. Chlorite structure responds to applied stress by compaction, reducing both pore size and volume. Chlorite platelets are plastically deformed in even the least strained samples. Kaolinite does not deform plastically in any of the samples examined. Deformation of kaolinite is restricted to toppling of the book structure. Dilatant crack growth was studied in two samples unloaded prior to failure. Uniaxially-strained samples deform primarily along grain boundaries, producing intergranular cracks and realignment of chlorite platelets. Intragranular crack density is linearly related to axial-strain, although grains are less fractured than in uniaxially-stressed samples tested at equivalent mean pressures. Cracks are rarely longer than a grain diameter. Nuclear-explosively deformed samples were recovered after the Rio Blanco gas stimulation experiment. (JGB)

  4. Impact-induced brittle deformation, porosity loss, and aqueous alteration in the Murchison CM chondrite

    NASA Astrophysics Data System (ADS)

    Hanna, Romy D.; Ketcham, Richard A.; Zolensky, Mike; Behr, Whitney M.

    2015-12-01

    X-ray computed tomographic scanning of a 44 g Murchison stone (USNM 5487) reveals a preferred alignment of deformed, partially altered chondrules, which define a prominent foliation and weak lineation in 3D. The presence of a lineation and evidence for a component of rotational, noncoaxial shear suggest that the deformation was caused by impact. Olivine optical extinction indicates that the sample can be classified as shock stage S1, and electron backscatter diffraction (EBSD) and electron microscopy reveal that plastic deformation within the chondrules was minimal and that brittle deformation in the form of fracturing, cataclasis, and grain boundary sliding was the dominant microstructural strain-accommodating mechanism. Textural evidence such as serpentine veins parallel to the foliation fabric and crosscutting alteration veins strongly suggest that some aqueous alteration post-dated or was contemporaneous with the deformation and that multiple episodes of fracturing and mineralization occurred. Finally, using the deformed shape of the chondrules we estimate that the strain experienced by Murchison was 17-43%. This combined with the current measured porosity of Murchison suggests that the original bulk porosity of Murchison prior to its deformation was 32.2-53.4% and likely at the upper end of this range due to chondrule compressibility, providing a unique estimate of pre-deformation porosity for a carbonaceous chondrite. Our findings suggest that significant porosity loss, deformation, and compaction from impact can occur on chondrite parent bodies whose samples may record only a low level of shock, and that significant chondrule deformation resulting in a chondrite foliation fabric can occur primarily through brittle processes and does not require plastic deformation of grains.

  5. Microwave Tomography Using Deformable Mirrors

    NASA Astrophysics Data System (ADS)

    Arunachalam, Kavitha; Udpa, Lalita; Udpa, Satish S.

    2008-09-01

    Microwave tomography aims to reconstruct the spatial distribution of the electrical property of penetrable objects using field measurements acquired from multiple views at single or multiple frequencies. This paper presents a novel microwave tomography technique to image penetrable scatterers using deformable mirrors. The deformable mirror consists of a continuum of radiating elements that yields multi-view field measurements for noninvasive characterization of the spatial dielectric property of the scatterer in the microwave regime. Computational feasibility of the proposed technique is presented for heterogeneous two dimensional dielectric scatterers.

  6. Deforming baryons into confining strings

    NASA Astrophysics Data System (ADS)

    Hartnoll, Sean A.; Portugues, Rubén

    2004-09-01

    We find explicit probe D3-brane solutions in the infrared of the Maldacena-Nuñez background. The solutions describe deformed baryon vertices: q external quarks are separated in spacetime from the remaining N-q. As the separation is taken to infinity we recover known solutions describing infinite confining strings in N=1 gauge theory. We present results for the mass of finite confining strings as a function of length. We also find probe D2-brane solutions in a confining type IIA geometry, the reduction of a G2 holonomy M theory background. The relation between these deformed baryons and confining strings is not as straightforward.

  7. Controllable objective with deformable mirrors

    SciTech Connect

    Agafonov, V V; Safronov, A G

    2004-03-31

    A new optical device - an objective with deformable mirrors and parameters controlled in the dynamic regime is proposed. The computer simulation of the objective is performed. The dependences of some parameters of the objective on the control voltage are determined. The simulation showed that the ranges of control of the rear focal segment and the focal distance for the objective with the focal distance 602 mm were 1057 and 340 mm, respectively, which is substantially greater than in the control of an equivalent deformable mirror. (laser applications and other topics in quantum electronics)

  8. Analytical volcano deformation source models

    USGS Publications Warehouse

    Lisowski, Michael

    2007-01-01

    Primary volcanic landforms are created by the ascent and eruption of magma. The ascending magma displaces and interacts with surrounding rock and fluids as it creates new pathways, flows through cracks or conduits, vesiculates, and accumulates in underground reservoirs. The formation of new pathways and pressure changes within existing conduits and reservoirs stress and deform the surrounding rock. Eruption products load the crust. The pattern and rate of surface deformation around volcanoes reflect the tectonic and volcanic processes transmitted to the surface through the mechanical properties of the crust.

  9. Fourth order deformed general relativity

    NASA Astrophysics Data System (ADS)

    Cuttell, Peter D.; Sakellariadou, Mairi

    2014-11-01

    Whenever the condition of anomaly freedom is imposed within the framework of effective approaches to loop quantum cosmology, one seems to conclude that a deformation of general covariance is required. Here, starting from a general deformation we regain an effective gravitational Lagrangian including terms up to fourth order in extrinsic curvature. We subsequently constrain the form of the corrections for the homogeneous case, and then investigate the conditions for the occurrence of a big bounce and the realization of an inflationary era, in the presence of a perfect fluid or scalar field.

  10. Deformation properties of lead isotopes

    NASA Astrophysics Data System (ADS)

    Tolokonnikov, S. V.; Borzov, I. N.; Lutostansky, Yu. S.; Saperstein, E. E.

    2016-01-01

    The deformation properties of a long lead isotopic chain up to the neutron drip line are analyzed on the basis of the energy density functional (EDF) in the FaNDF0 Fayans form. The question of whether the ground state of neutron-deficient lead isotopes can have a stable deformation is studied in detail. The prediction of this deformation is contained in the results obtained on the basis of the HFB-17 and HFB-27 Skyrme EDF versions and reported on Internet. The present analysis reveals that this is at odds with experimental data on charge radii and magnetic moments of odd lead isotopes. The Fayans EDF version predicts a spherical ground state for all light lead isotopes, but some of them (for example, 180Pb and 184Pb) prove to be very soft—that is, close to the point of a phase transition to a deformed state. Also, the results obtained in our present study are compared with the predictions of some other Skyrme EDF versions, including SKM*, SLy4, SLy6, and UNE1. By and large, their predictions are closer to the results arising upon the application of the Fayans functional. For example, the SLy4 functional predicts, in just the same way as the FaNDF0 functional, a spherical shape for all nuclei of this region. The remaining three Skyrme EDF versions lead to a deformation of some light lead isotopes, but their number is substantially smaller than that in the case of the HFB-17 and HFB-27 functionals. Moreover, the respective deformation energy is substantially lower, which gives grounds to hope for the restoration of a spherical shape upon going beyond the mean-field approximation, which we use here. Also, the deformation properties of neutron-rich lead isotopes are studied up to the neutron drip line. Here, the results obtained with the FaNDF0 functional are compared with the predictions of the HFB-17, HFB-27, SKM*, and SLy4 Skyrme EDF versions. All of the EDF versions considered here predict the existence of a region where neutron-rich lead isotopes undergo

  11. Neutron scattering on deformed nuclei

    NASA Astrophysics Data System (ADS)

    Hansen, L. F.; Haight, R. C.; Pohl, B. A.; Wong, C.; Lagrange, Ch.

    1985-01-01

    Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9Be, C, 181Ta, 232Th, 238U, and 239Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune, and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonably good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP.

  12. Cavity coalescence in superplastic deformation

    SciTech Connect

    Stowell, M.J.; Livesey, D.W.; Ridley, N.

    1984-01-01

    An analysis of the probability distribution function of particles randomly dispersed in a solid has been applied to cavitation during superplastic deformation and a method of predicting cavity coalescence developed. Cavity size distribution data were obtained from two microduplex nickel-silver alloys deformed superplastically to various extents at elevated temperature, and compared to theoretical predictions. Excellent agreement occurred for small void sizes but the model underestimated the number of voids in the largest size groups. It is argued that the discrepancy results from a combination of effects due to non-random cavity distributions and to enhanced growth rates and incomplete spheroidization of the largest cavities.

  13. Learning deformation and structure simultaneously: in situ endograft deformation analysis.

    PubMed

    Langs, Georg; Paragios, Nikos; Desgranges, Pascal; Rahmouni, Alain; Kobeiter, Hicham

    2011-02-01

    The learning of the shape and appearance behavior of complex anatomical structures is of growing importance in the successful use of medical imaging data. We propose a method to simultaneously learn a model of shape variation and the behavioral structure of objects in volumetric data sets. The algorithm performs a group-wise registration of a set of examples, and accounts for the heterogeneous deformation or variability properties of the data. We use the method for the in situ analysis of endograft deformation in the thoracic aorta during the cardiac cycle. The method is based on an emerging model of the shape variation, which is learned autonomously from a gated computed tomography sequence. It automatically adapts to the highly non-uniform elasticity properties of the structure during learning. The resulting deformation model is used for the measurement of global and local characteristics of the endograft movement. The method allows for the in situ localization of the stent during the cardiac cycle, and the measurement of its deformation. Furthermore, it makes the comparison of different endograft designs possible, and can serve as a basis for fitting a physical model of the endograft- and vessel surface to individual patients. The latter is essential for long-term risk assessment of the impact of endografts in highly mobile areas. We evaluate the approach on 10 data sets from patients that underwent endograft placement after traumatic ruptures of the thoracic aorta. PMID:20675181

  14. Space-based monitoring of ground deformation

    NASA Astrophysics Data System (ADS)

    Nobakht Ersi, Fereydoun; Safari, Abdolreza; Gamse, Sonja

    2016-07-01

    Ground deformation monitoring is valuable to understanding of the behaviour of natural phenomena. Space-Based measurement systems such as Global Positioning System are useful tools for continuous monitoring of ground deformation. Ground deformation analysis based on space geodetic techniques have provided a new, more accurate, and reliable source of information for geodetic positioning which is used to detect deformations of the Ground surface. This type of studies using displacement fields derived from repeated measurments of space-based geodetic networks indicates how crucial role the space geodetic methods play in geodynamics. The main scope of this contribution is to monitor of ground deformation by obtained measurements from GPS sites. We present ground deformation analysis in three steps: a global congruency test on daily coordinates of permanent GPS stations to specify in which epochs deformations occur, the localization of the deformed GPS sites and the determination of deformations.

  15. Retrospective Birth Dating of Cells

    SciTech Connect

    L.Spalding, K; Bhardwaj, R D; Buchholz, B A; Druid, H; Frisen, J

    2005-04-19

    The generation of cells in the human body has been difficult to study and our understanding of cell turnover is limited. Extensive testing of nuclear weapons resulted in a dramatic global increase in the levels of the isotope {sup 14}C in the atmosphere, followed by an exponential decrease after the test ban treaty in 1963. We show that the level of {sup 14}C in genomic DNA closely parallels atmospheric levels, and can be used to establish the time point when the DNA was synthesized and cells were born. We use this strategy to determine the age of cells in the cortex of the adult human brain, and show that whereas non-neuronal cells are exchanged, occipital neurons are as old as the individual, supporting the view that postnatal neurogenesis does not take place in this region. Retrospective birth dating is a generally applicable strategy that can be used to measure cell turnover in man under physiological and pathological conditions.

  16. Sexual assault in dating relationships.

    PubMed

    Rhynard, J; Krebs, M; Glover, J

    1997-03-01

    This article focuses on acquaintance rape, which under Canadian law constitutes a form of sexual assault. Frequency of acquaintance rape often is underestimated due to under-reporting, resulting in a local perception that acquaintance rape rarely occurs in a small Canadian community. A survey was conducted to determine whether acquaintance rape does occur in this community. One hundred sixty-four male and female students from grades 8-12 completed a questionnaire. Twenty-six percent of respondents reported being forced into some type of sexual activity. Based on the survey, this article explores the type of force used, the relationship between acquaintance rape and use of alcohol and drugs, and the relationship between acquaintance rape and the ability to indicate to a partner to stop a behavior. Results confirmed a need to develop programs to prevent rather than merely respond to issues of sexual assault on a date. PMID:9071669

  17. Thermoluminescence dating of Hawaiian basalt

    USGS Publications Warehouse

    May, Rodd James

    1979-01-01

    The thermoluminescence (TL) properties of plagioclase separates from 11 independently dated alkalic basalts 4,500 years to 3.3 million years old and 17 tholeiitic basalts 16 years to 450,000 years old from the Hawaiian Islands were investigated for the purpose of developing a TL dating method for young volcanic rocks. Ratios of natural to artificial TL intensity, when normalized for natural radiation dose rates, were used to quantify the thermoluminescence response of individual samples for age-determination purposes. The TL ratios for the alkalic basalt plagioclase were found to increase with age at a predictable exponential rate that permits the use of the equation for the best-fit line through a plot of the TL ratios relative to known age as a TL age equation. The equation is applicable to rocks ranging in composition from basaltic andesite to trachyte over the age range from about 2,000 to at least 250,000 years before present (B.P.). The TL ages for samples older than 50,000 years have a calculated precision of less than :t 10 percent and a potential estimated accuracy relative to potassium-argon ages of approximately :t 10 percent. An attempt to develop a similar dating curve for the tholeiitic basalts was not as successful, primarily because the dose rates are on the average lower than those for the alkalic basalts by a factor of 6, resulting in lower TL intensities in the tholeiitic basalts for samples of equivalent age, and also because the age distribution of dated material is inadequate. The basic TL properties of the plagioclase from the two rock types are similar, however, and TL dating of tholeiitic basalts should eventually be feasible over the age range 10,000 to at least 200,000 years B.P. The average composition of the plagioclase separates from the alkalic basalts ranges from oligoclase to andesine; compositional variations within this range have no apparent effect on the TL ratios. The average composition of the plagioclase from the tholeiitic

  18. What are we Dating? An Evaluation of Chemical Pretreatment Methods for AMS 14C Dating of Peat

    NASA Astrophysics Data System (ADS)

    Scharer, K.; Kashgarian, M.; Zermeno, P.; Kurdyla, D.

    2006-12-01

    Progressive deformation of landforms commonly creates depositional environments where organic-rich sediment layers such as peats are preserved (e.g., Wrightwood, Coachella, Vedanta paleoseismic sites). Field studies using 3-D excavation methods can improve estimates of landform displacement, while AMS 14C dating of well characterized organic material sampled during field work is essential for determining slip rates associated with landform deformations. Here we present results of a test of chemical pretreatment used for AMS 14C dating of peat in an attempt to better characterize what we are dating and how the age of organic fractions is affected by different extraction procedures. Standard chemical pretreatment of organic materials for AMS 14C analysis typically isolates three broad organic fractions: humic acids, humin, and fulvic acids. Humic acids, the focus of this study, are thought to result from complex degradation of lignin and related compounds, and in principle should provide the most accurate age of in-situ organic layers (i.e., the decomposed leaf of a plant). The extraction of humic acid from organic-rich sediments or soils is operationally defined by chemical solubility and is not directly associated with a particular starting material. This means that chemical extracts are likely to contain humic acids derived from different starting materials which may have different ages and origins. In earlier studies of the duration of chemical pretreatment, Cook et al. (1998) found that increasing the amount of time that peat was exposed to NaOH increased the quantity of humics extracted, and Williams (1989) reported that increasing the duration of the NaOH wash will sometimes, but not always, result in an older sample age. Thus, a long base extraction time may solubilize more resistant and potentially older humics. To test whether the duration of the base extraction step affects dates, we extracted humic acid from three peat layers from the Wrightwood

  19. Electrostatics of Deformable Lipid Membranes

    PubMed Central

    Vorobyov, Igor; Bekker, Borislava; Allen, Toby W.

    2010-01-01

    Abstract It was recently demonstrated that significant local deformations of biological membranes take place due to the fields of charged peptides and ions, challenging the standard model of membrane electrostatics. The ability of ions to retain their immediate hydration environment, combined with the lack of sensitivity of permeability to ion type or even ion pairs, led us to question the extent to which hydration energetics and electrostatics control membrane ion permeation. Using the arginine analog methyl-guanidinium as a test case, we find that although hydrocarbon electronic polarizability causes dramatic changes in ion solvation free energy, as well as a significant change (∼0.4 V) in the membrane dipole potential, little change in membrane permeation energetics occurs. We attribute this to compensation of solvation terms from polar and polarizable nonpolar components within the membrane, and explain why the dipole potential is not fully sensed in terms of the locally deformed bilayer interface. Our descriptions provide a deeper understanding of the translocation process and allow predictions for poly-ions, ion pairs, charged lipids, and lipid flip-flop. We also report simulations of large hydrophobic-ion-like membrane defects and the ionophore valinomycin, which exhibit little membrane deformation, as well as hydrophilic defects and the ion channel gramicidin A, to provide parallels to membranes deformed by unassisted ion permeation. PMID:20550903

  20. What Is Rape and Date Rape?

    MedlinePlus

    ... What is rape and date rape? What is rape and date rape? Get help National Sexual Assault Hotline 800-656- ... drinking, it is NOT your fault. What is sexual assault? Sexual assault and abuse is any kind of ...

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