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Sample records for accretionary prism development

  1. Structural development of the North-Sumatran Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Geersen, Jacob; McNeill, Lisa; Henstock, Tim; Gaedicke, Christoph; Ladage, Stefan; Kopp, Heidrun

    2014-05-01

    The accretionary prism of northern Sumatra differs from classical prism examples in a number of ways. It consists of an almost flat, up to 130 km wide plateau and a small but steep outer wedge. Along its entire width from the deformation front to the rear of the prism it is composed of multiple, up to 5 km thick undeformed blocks of layered sediments that are adjacent to seismically chaotic units. The intact thrust blocks are the same thickness as the 5 km thick incoming sediment section and are usually bounded on both sides by steep landward and seaward vergent faults. Similar sedimentary blocks, bounded by conjugate normal faults that relate to bending of the subducting oceanic plate, are also observed in the incoming section. Another striking structural feature is the occurrence of landward vergent (seaward dipping) thrust faults in the outer prism. These unusual deformation structures differ from the common fold-and-thrust belt model in the dip direction of the thrust sheets and have, to a similar extent, only been reported from the Cascadia margin. Seismic reflection data also image a series of high-amplitude negative-polarity reflective faults in the prism and the incoming sediment section that only produce minor displacements. These faults do not intersect the seafloor or the plate-boundary at depth and dip both landward and seaward at a lower angle than most prism thrust faults. We use a combination of reflection seismic and bathymetric data to investigate the parameters and processes that lead to the development of the unusual prism structure and morphology. In addition to detailed structural and morphologic descriptions we summarize and compare fault dips in the incoming section and the prism in order to analyse how proto-deformation of oceanic plate sediments influences the structural development of the prism. We present a conceptual model in line with our observations that could be transferable to accretionary margins with a similar geologic history

  2. into the accretionary prism

    NASA Astrophysics Data System (ADS)

    Okamoto, Atsushi; Musya, Michimasa; Hashimoto, Yoshitaka; Tsuchiya, Noriyoshi

    2014-12-01

    Carbon dioxide and methane are major components in geofluids; however, there is little evidence showing how C-H-O fluids evolve in a subduction zone. We investigated fluid inclusions in quartz veins from the Eocene-Oligocene Shimanto belt (Murotohanto subbelt) on Muroto Peninsula, SW Japan using microthermometry and laser Raman spectroscopy. Quartz veins that cut the cleavage of the host rocks in the Murotohanto subbelt contain one-phase carbonic inclusions (CH4) and two-phase aqueous inclusions (CH4 ± CO2 vapor and H2O liquid). The vapor in the two-phase inclusions is essentially CH4 in the northern part of the belt and a CO2-CH4 mixture in the southern part; values of [InlineEquation not available: see fulltext.] (=CO2 / (CO2 + CH4)) vary from 0 to 0.9. Within a single CO2-bearing vein, [InlineEquation not available: see fulltext.] values decrease from the vein wall ([InlineEquation not available: see fulltext.] = 0.5 to 0.9) to the vein center ([InlineEquation not available: see fulltext.] = 0), and the homogenization temperature increases from approximately 180°C to 240°C-250°C, indicating a transition of the carbonic species from CO2-CH4 to CH4 during vein formation. CO2-dominant fluids are rare in most accretionary prisms formed under low-grade metamorphic conditions, and the generation of CO2 cannot be explained by diagenesis of organic matter in sediments under the P-T conditions of formation of the CO2-bearing veins (235°C to 245°C, 165 to 200 MPa). The CO2 fluids are distributed preferentially near an out-of-sequence thrust that brings the Murotohanto subbelt into contact with the late Oligocene-early Miocene Nabae subbelt and its many volcanic and intrusive rocks. We therefore suggest that the CO2 fluids were generated in association with near-trench magmatism during the middle Miocene and that the fluids were injected and mixed with the CH4 pore fluids of the sediments in the accretionary prism.

  3. Initiation and development of slickenlined surfaces in clay-rich material of the Nankai Trough accretionary prism

    NASA Astrophysics Data System (ADS)

    Crespo-Blanc, Ana; Schleicher, Anja

    2016-04-01

    During the International Ocean Discovery Program (IODP) Expedition 348, which is part of the Nankai Trough Seismogenic Zone Experiment (stage 3), the drilling vessel Chikyu advanced the deep riser hole at Site C0002, located 80 km offshore of the Kii Peninsula (Japan), from a depth of 860 meters below sea floor (mbsf) to 3058.5 mbsf. Underlying the Kumano Basin sediments, the Nankai accretionary prism appears, below 975.5 mbsf. It accreted during Upper Miocene to Pliocene times and is formed mainly by turbiditic silty claystone with rarely observed sandstone intercalations. Cuttings from both the 1-4 mm and >4 mm size fractions were investigated, showing slickenlined surfaces and deformation bands together with carbonate veins throughout the entire section from 1045.5 until 3058.5 mbsf. A scaly fabric is increasingly observed below approximately 2400 mbsf. Clay-rich cuttings were selected at different depth for specific SEM-EDS analysis, in order to investigate the initiation and development of the slickenlined surfaces, from both a structural and mineralogical point of view. Two end-members of the slickenlined surface types were observed: a) isolated smooth and uniform planes, between 20 and 50 μm long, formed by single grains of smectite with marked lineations and frequently jagged boundaries and b) microfaults (longer than 100 μm) with sharp boundaries to the undeformed rock, formed by aggregates of illite and smectite and with a well-developed lineation. In transition between these two end-member types, planes that are apparently unconnected draw a single plane and show subparallel lineations. Concerning the orientation of the slickenlines, it seems to be coherent with that observed in an array of conjugated faults, i.e. all the slickenlines belong to the same plane, in turn sub-perpendicular to the intersection of conjugated planes. These observations suggest that the slickenlined surfaces initiated along single grains of smectite and that with increasing

  4. Sediment compaction and fluid migration in the Makran Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Minshull, Tim; White, Robert

    1989-06-01

    The Makran continental margin in the Gulf of Oman forms the seaward extremity of an accretionary sediment prism which extends several hundred kilometers inland. A recently acquired multichannel seismic reflection profile shot across the margin imaged the structure of the prism in greater detail than was previously possible and allowed us to investigate the relationship between deformation and pore fluid motion in the region. Velocity analyses of the common midpoint gathers reveal a marked change in velocity structure at the toe of the accretionary wedge, as seen in previous sonobuoy wide-angle data. Accreted sediments show significantly higher vertical velocity gradients than those of sediments entering the prism; this change is interpreted as due to porosity reduction as pore fluids are squeezed out of the compacting sediment. A prominent "bottom simulating reflector" appears 500-800 m beneath the sea bed. Several lines of evidence suggest that this reflector represents the base of a gas hydrate zone underlain by widespread free gas, which may be exsolved from pore water migrating from deep within the sediment pile up permeable fault planes imaged in the profile. The hydrate reflector appears to shallow in the region of some faults, suggesting a temperature anomaly due to the presence of warm pore fluids. A heat flow profile derived from the depth of the hydrate reflector does not show the expected landward decrease as the sediment pile thickens. Simple thermal modeling suggests that advective heat flow within the prism may explain this anomaly. The inferred presence of overpressured pore fluids in the Makran suggests that accreted sediments have a low permeability. The seismic evidence suggests a two-stage compaction process, with rapid initial dewatering through intergranular permeability as sediment enters the prism followed by a buildup of pore pressure as the permeability decreases and fluid migration is restricted to fault zones.

  5. Structure of a growing accretionary prism, Hikurangi margin, New Zealand

    NASA Astrophysics Data System (ADS)

    Davey, F. J.; Hampton, M.; Childs, J.; Fisher, M. A.; Lewis, K.; Pettinga, J. R.

    1986-08-01

    The Hikurangi margin of eastern North Island, New Zealand, represents the feather edge of the Indian plate at its convergent boundary with the subducting Pacific plate. A migrated seismic reflection profile across this margin clearly displays the structural evolution of an accretionary prism. A 25-km-wide band of “protothrusts” is delineated between the toe of the slope and a converging seamount; this illustrates an early stage in the seaward propagation of a deformation front. Landward-tilted trench-slope basins are separated by ridges that have clearly defined thrusts, which appear to sole out at a decollement. The decollement continues at an angle of only 3° beneath the 150-km-wide margin to a depth of 14 km near the coast where it coincides with an onshore zone of high seismicity.

  6. Extreme efficiency of mud volcanism in dewatering accretionary prisms

    NASA Astrophysics Data System (ADS)

    Kopf, Achim; Klaeschen, Dirk; Mascle, Jean

    2001-07-01

    Drilling results from two mud volcanoes on the Mediterranean Ridge accretionary complex as well as bottom sampling and the wealth of geophysical data acquired recently have provided fundamental knowledge of the 3D geometry of mud extrusions. Mud volcanism is generally related to buoyancy (density inversion), and is triggered by the collision of the African and Eurasian blocks, forcing undercompacted clayey sediments to extrude along faults in the central and hinterlandward parts of the prism. Volumetric estimates of extruded mud in several well-studied areas were based on pre-stack depth-migrated seismic profiles across the entire, up to >150 km wide, prism. The resulting volumes of mud were combined with ages from mud dome drilling, so that rates of mud extrusion were obtained. Subtracting the solid rock mass from the bulk mud volume using physical property data, fluid flux as a function of mud volcanism alone has been quantified for the first time. The volume of fluid extruding with the mud is found to be variable, but reaches up to 15 km 3 fluid per km trench length and Ma along cross sections with abundant mud volcanoes. Such large fluid quantities in a region some 50-150 km behind the deformation front exceed estimates from those elsewhere (where undoubtedly the majority of the interstitial fluid is lost due to compaction). Such fluids near the backstop are likely to result predominantly from mineral dehydration and diagenetic reactions at depth, and consequently provide a window to understand deeper processes along the deep décollement. More importantly, the enormous rates with which such fluids and liquified mud escape along the out-of-sequence faults alter fluid budget calculations in subduction zones drastically.

  7. Implications of Faulting Styles in the Outer Wedge of the Nankai Accretionary Prism, Japan

    NASA Astrophysics Data System (ADS)

    Kington, J. D.; Tobin, H. J.

    2009-12-01

    The Nankai Trough, Japan near Kumano Basin displays a well developed accretionary prism with a major out-of-sequence “megasplay” thrust separating the recently active outer wedge of the prism from the forearc basin deposits. While not in the seismogenic zone, this thrust is thought to play a key role in tsunamigenesis by transferring deeper coseismic slip to the seafloor. Understanding the development of this fault requires a detailed understanding of the kinematics and structure of the outer wedge of the accretionary prism. The outer wedge of the Nankai accretionary prism consists of an in-sequence series of landward-dipping thrusts that record two directions of shortening. Based on 3D reflection seismic, older thrusts and their associated folds strike ~225 degrees, almost exactly perpendicular to plate motion in the area, which has an azimuth of 314 (Zang, et al, 2002). The youngest thrusts, including the megasplay at the rear of the outer wedge, trend 240-245 degrees, subparallel to the margin in the area, which trends roughly 250. This suggests two possibilities: 1) the older thrusts formed during a period of relatively strong coupling with the subducting slab, perhaps due to highly irregular oceanic basement topography which has since been subducted, or 2) the trench margin had been previously indented by a subducted seamount and has since been rebuilding. In addition, two right lateral tear faults with offsets of approximately 1km cut the fold-thrust belt of the outer wedge. These faults cleanly offset the fold hinge of faults striking perpendicular to plate motion and interact with the oldest faults that strike parallel to the margin, implying that their timing is coincident with the change in shortening direction. Therefore, these tear faults may accommodate along-strike changes in the taper angle of the accretionary prism following the subduction of irregular basement topography. Significant normal faulting within the seismically imaged portion of the

  8. Deformation-induced diagenesis and microbial activity in the Nankai accretionary prism

    NASA Astrophysics Data System (ADS)

    Famin, V.; Andreani, M.; Boullier, A. M.; Raimbourg, H.; Magnin, V.

    2014-12-01

    We performed a microscopic and chemical study of diagenetic reactions in deformation microstructures within deep mud sediments from the Nankai accretionary prism (SW Japan) collected during IODP Expedition 315. Our study reveals that deformation microstructures localize the crystallization of pyrite, a diagenetic reaction also found in large megasplay faults of the prism. Textural observation shows that pyrite crystallization is synchronous of the sediment deformation. The framboidal shape of pyrite crystals, the barium depletion and the strong arsenic enrichment observed in deformation microstructures compared with the sediment matrix, suggest that pyrite crystallization is mediated by the proliferation of anoxic archae. During scientific drilling expeditions IODP 315, 316 and 319, microbial life has been evidenced at depths of up to 800 m below the sea floor by the presence of biogenic methane and sulfate reducers in sediments. We suggest that deformation structures localize microbial proliferation because the fracturing of silicate minerals produces hydrogen, a necessary compound for bacteria under anoxic conditions. Bacteria proliferate as long as active deformation supplies hydrogen, and vanish when the deformation stops. The development of bacteria in deformation structures impacts our mechanical understanding of fault zones in accretionary prisms: Firstly, bacterial activity converts carbon from organic matter and hydrogen into methane and/or water, which may alter the fluid budget of fault zones and the recurrence of dynamic ruptures in megathrusts. Secondly, the abundance of bacteria could be used to recognize active fault zones from inactive ones in drilling cores.

  9. Fold Thrust Belt Kinematics from 3D Seismic Imaging along the NanTroSEIZE Transect, Nankai Accretionary Prism, Japan.

    NASA Astrophysics Data System (ADS)

    Kington, J. D.; Tobin, H.; Moore, G.

    2008-12-01

    The accretionary prism of the Nankai Trough, Japan provides an excellent location to study the kinematics of a fold and thrust belt developed primarily in low permeability units. Recently acquired 3D reflection seismic data covering a 12 x 56 km area from the Kumano basin seaward to the deformation front reveals three structural domains within the frontal accretionary prism. The farthest seaward domain of the prism consists closely-spaced, apparently in-sequence thrust sheets forming a steep critical taper angle. The primary decollement beneath these thrusts ramps upsection above a topographic high within the oceanic basement. The farthest landward domain within the study area consists of the hanging wall of an apparently out of sequence megasplay thrust fault that dips landward to the top of the oceanic crust. The central structural domain within the prism consists of thrust sheets formed above a decollement approximately 2 km above the top of the oceanic crust, above the decollement associated with the more seaward thrusts. These thrusts are more widely spaced than those nearer the deformation front and are blanketed with syn and post kinematic sediments. Synkinematic sediments indicate that thrusts in the most seaward and most landward structural domains within the prism are the most active, though some reactivation of structures in the middle domain has occurred. Additionally, gas hydrate bottom simulating reflectors (BSRs) in the lowermost portions of the prism are present as discrete bands striking parallel to thrusts. These BSRs occur primarily along the most active thrusts, and are only present as small patches within the central structural domain of the prism. As these are expected to be the result of fluid migration along faults and permeable structures, they provide insight into the hydrologic controls on thrusting within the accretionary prism.

  10. Low-frequency tremors associated with reverse faults in a shallow accretionary prism

    NASA Astrophysics Data System (ADS)

    Obana, Koichiro; Kodaira, Shuichi

    2009-09-01

    The shallow part of a seismogenic subduction zone is thought to play an important role in tsunami genesis during large interplate thrust earthquakes. Near the updip portion of the seismogenic zone along the Nankai trough, splay faults, which are major active reverse faults in the accretionary prism, likely rupture during large interplate earthquakes such as the 1944 Mw 8.2 Tonankai earthquake off Kii Peninsula. We observed low-frequency tremors associated with reverse faults in a shallow accretionary prism off Kii Peninsula at close range by using ocean bottom seismographs. The tremors were characterized by a dominant frequency range of 2-8 Hz and a lack of energy in the frequency range above 10 Hz. Their duration ranged from tens of seconds to a few minutes. Their source locations lay in three clusters on the landward slope of the Nankai trough. Activity in each cluster continued for from one day to two weeks. Many of the low-frequency tremors were located near the shallowest part of a major splay fault. The episodic activity of low-frequency tremors and of previously reported very-low-frequency earthquakes, which indicate reverse faulting in the shallow accretionary prism, suggests that the reverse faults in the accretionary prism are conditionally stable faults that can become unstable under sufficiently strong dynamic loading, such as that caused by a large earthquake. Such reverse faults, as typified by a splay fault, can rupture during large interplate earthquakes and generate large tsunamis.

  11. Structure and Stratigraphy of the Barbados Accretionary Prism and the Tobago Forearc Basin

    NASA Astrophysics Data System (ADS)

    Chaderton, N. A.; Wood, L. J.; Mann, P.

    2004-12-01

    The relationship between the Lesser Antilles island arc, the Tobago forearc basin, and the Barbados accretionary prism shows classic convergent margin geometry. Barbados is the only emergent part of the accretionary prism with 80% of the island's land area being covered by Pleistocene limestone. Erosion of the limestone cap in the northeastern part of the island exposes older rocks of the prism. A 450-km2 2-D seismic data volume allows extension of these stratigraphic units offshore and definition of a regional structural framework. The relationship between the unit identified onshore as the Early Eocene to Middle Miocene Oceanic Formation and the basal unit, the intensively folded and faulted Eocene prism rocks of the Scotland Group, has long been debated. Previous proposals claim that the Oceanic Formation, consisting of pelagic clays with some ash beds, is allochthonous and has been thrusted into its present position above accreted sediments of the Scotland Group. However, seismic data show no evidence of nappes-the basis for the overthrusting hypothesis. Seismic interpretation presented here supports the opposing view that the Oceanic Formation and its offshore equivalent in the offshore Tobago forearc basin was deposited in situ and onlap the older, more highly deformed rocks of the accretionary prism. Previous workers proposed that the region's extensive mud diapirism (identified onshore as the Joes River Formation) has caused the emergence of Barbados, which continues to rise 0.44 mm/yr. However, seismic lines suggest that the island's emergence and present-day uplift is related to footwall uplift along a large, NE-striking normal fault off the east coast of the island.

  12. Fluid seepage, Deformation, Tectonics and Accretionary Prism Formation in Two Different Settings of the Nankai Accretionary Prism- Dive Results of YK05-08 Leg 2

    NASA Astrophysics Data System (ADS)

    Ogawa, Y. F.; Kawamura, K.; Anma, R.; Yokoyama, S.; Kawakami, S.; Moore, G. F.; Dilek, Y.; S. Y.

    2005-12-01

    Fluid seepages recognized by the presence of bacterial mats, chemosynthetic biocommunities, and carbonate deposits were critically analyzed in relation to large to small scale deformation features in two different settings of the Nankai accretionary prism by the manned submersible Shinkai 6500 during JAMSTEC cruise YK05-08 Leg 2. We present dive profiles in the Shionomisaki and Tenryu submarine canyons that form a 3D transect extending from the outer-arc ridge formed by out-of-sequence thrusts (OOST ridge) to the prism toe. Ten dives in addition to six previous dives (including three unmanned ROV Kaiko dives) verified that Shionomisaki Canyon exposes typical accretionary prism features, including regular repetition of offscraping and underplating structure, whereas Tenryu Canyon shows highly modified structures caused by the collisional subduction of the Paleo-Zenisu ridge of the Izu island arc. The fluid seepages were observed in three different settings: (1) just beneath large thrust faults which demarcate the sharp ridge foot; (2) the open fractured crests of the thrust-anticline folds; and (3) the conspicuous circular expression on the OOST ridge top. The last case and previously known examples in the forearc basin setting are both examples of large scale seepage that might be due to intermittent, sometimes explosive methane seepage, whereas the first two cases are of constant flow rate of smaller magnitude. Such differences may be due to differences in the tectonic setting between the two; the large flow rate example is due to open or strike-slip regime tectonics where large amount of seepage occurs along the high permeability zones. In contrast, the small flow rate example is seepage along a thrust, with rather constant (although intermittent during co-seismic stage) flow rate along thrust faults which are of relatively lower permeability. In addition, we verified some carbonate veins in fractured or sheared rocks along faults, and the various deformation

  13. Synchrotron texture analysis of clay-rich sediments from the Nankai trench and accretionary prism

    NASA Astrophysics Data System (ADS)

    Schumann, Kai; Stipp, Michael; Leiss, Bernd; Behrmann, Jan-Hinrich

    2013-04-01

    Synchrotron diffraction is the most suitable tool for fast multi-mineral phase texture analysis of water-containing clay rich sediment samples due to short wavelengths (in the range of 0.12 Å), high energy radiation and a resulting mm- to cm-scale sample penetration. We carried out synchrotron texture analysis on a sample set from the Nankai trench and accretionary prism offshore Japan. Samples were encountered by IODP Expeditions 315, 316 and 333 of the NanTroSEIZE project from a depth range between 25 mbsf (meters below seafloor) and 522 mbsf. The accretionary prism sediments have a relatively uniform composition of approximately 40% clay minerals, 25% quartz, 25% feldspar, and up to 10% calcite. A first sample set analyzed was taken as recovered from drilling; a second sample set was additionally experimentally deformed in a triaxial deformation apparatus up to axial strains of 60%. Measurements were carried out at DESY (German Electron Synchrotron source) in Hamburg. In order to measure complete pole figures sample cylinders of 2 cm in diameter and 2 cm in length were measured in a phi angle-range from -90 to +90° in 5° steps. Rietveld refinement results using the MAUD program package show that the composition of the IODP Expedition 333 samples from the incoming plate differs slightly from the relatively uniform IODP Expedition 315 and 316 samples of the accretionary prism. They contain ~35% clay minerals, ~30% quartz and ~35% feldspar. For IODP Expedition 315 and 316 samples the Rietveld refinement results correspond to the standard XRD data. The synchrotron texture results of the recovered samples without experimental deformation show an increasingly strong preferred orientation of the clay minerals with increasing sediment depth for the incoming plate. Interestingly, also feldspar shows a significant texture, which is likely due to a shape fabric of the grains. The sediment texture can be explained by compaction and porosity reduction with increasing

  14. Geochemical and geothermal evidence for fluid migration in the Barbados Accretionary Prism (ODP leg 110)

    NASA Astrophysics Data System (ADS)

    Vrolijk, Peter; Fisher, Andrew; Gieskes, Joris

    Measured geochemical and geothermal effects of fluid migration in the northern Barbados accretionary prism indicate that: (1) fluid flows laterally along low-angle active faults; (2) the entire length of the Leg 110 transect is a fluid discharge zone; (3) migration results in heating of sediments across the transect but most strongly at the deformation front; and (4) migration results in dilution of pore water-Cl and 18O enrichment more in the arcward than the seaward side of the prism, suggesting that the Cl-poor, 18O-rich fluids that intrude the prism are derived from smectiteillite reactions occurring arcward. These conclusions have strengthened those derived from the initial appraisal of shipboard data, modified ideas about where fluids are heated most and where the geochemistry is strongly altered, and provided new ideas about the sources of fluids and their relative contributions.

  15. Biogas production using anaerobic groundwater containing a subterranean microbial community associated with the accretionary prism.

    PubMed

    Baito, Kyohei; Imai, Satomi; Matsushita, Makoto; Otani, Miku; Sato, Yu; Kimura, Hiroyuki

    2015-09-01

    In a deep aquifer associated with an accretionary prism, significant methane (CH₄) is produced by a subterranean microbial community. Here, we developed bioreactors for producing CH₄ and hydrogen (H₂) using anaerobic groundwater collected from the deep aquifer. To generate CH₄, the anaerobic groundwater amended with organic substrates was incubated in the bioreactor. At first, H₂ was detected and accumulated in the gas phase of the bioreactor. After the H₂ decreased, rapid CH₄ production was observed. Phylogenetic analysis targeting 16S rRNA genes revealed that the H₂ -producing fermentative bacterium and hydrogenotrophic methanogen were predominant in the reactor. The results suggested that syntrophic biodegradation of organic substrates by the H₂ -producing fermentative bacterium and the hydrogenotrophic methanogen contributed to the CH₄ production. For H₂ production, the anaerobic groundwater, amended with organic substrates and an inhibitor of methanogens (2-bromoethanesulfonate), was incubated in a bioreactor. After incubation for 24 h, H₂ was detected from the gas phase of the bioreactor and accumulated. Bacterial 16S rRNA gene analysis suggested the dominance of the H₂ -producing fermentative bacterium in the reactor. Our study demonstrated a simple and rapid CH4 and H2 production utilizing anaerobic groundwater containing an active subterranean microbial community. PMID:25267392

  16. Biogas production using anaerobic groundwater containing a subterranean microbial community associated with the accretionary prism

    PubMed Central

    Baito, Kyohei; Imai, Satomi; Matsushita, Makoto; Otani, Miku; Sato, Yu; Kimura, Hiroyuki

    2015-01-01

    In a deep aquifer associated with an accretionary prism, significant methane (CH4) is produced by a subterranean microbial community. Here, we developed bioreactors for producing CH4 and hydrogen (H2) using anaerobic groundwater collected from the deep aquifer. To generate CH4, the anaerobic groundwater amended with organic substrates was incubated in the bioreactor. At first, H2 was detected and accumulated in the gas phase of the bioreactor. After the H2 decreased, rapid CH4 production was observed. Phylogenetic analysis targeting 16S rRNA genes revealed that the H2-producing fermentative bacterium and hydrogenotrophic methanogen were predominant in the reactor. The results suggested that syntrophic biodegradation of organic substrates by the H2-producing fermentative bacterium and the hydrogenotrophic methanogen contributed to the CH4 production. For H2 production, the anaerobic groundwater, amended with organic substrates and an inhibitor of methanogens (2-bromoethanesulfonate), was incubated in a bioreactor. After incubation for 24 h, H2 was detected from the gas phase of the bioreactor and accumulated. Bacterial 16S rRNA gene analysis suggested the dominance of the H2-producing fermentative bacterium in the reactor. Our study demonstrated a simple and rapid CH4 and H2 production utilizing anaerobic groundwater containing an active subterranean microbial community. PMID:25267392

  17. The Late Cambrian Takaka Terrane, NW Nelson, New Zealand: Accretionary-prism development and arc collision followed by extension and fan-delta deposition at the SE margin of Gondwana

    NASA Astrophysics Data System (ADS)

    Pound, K. S.

    2013-12-01

    Re-evaluation of field and lab data indicates that the Cambrian portion of the Takaka Terrane in the Cobb Valley area of NW Nelson, New Zealand preserves the remnants of an accretionary prism complex, across which the Lockett Conglomerate fan-delta was deposited as a consequence of extension. Previous work has recognized that the structurally disrupted lower Takaka Terrane rocks present an amalgam of sedimentary and igneous rocks generated prior to convergence (Junction Formation) or during convergence (Devil River Volcanics Group, Haupiri Group), including arc-related and MORB components. Portions of the sequence have in the past been loosely described as an accretionary prism. Reevaluation of the detailed mapping, sedimentological and provenance studies shows that remnants of a stratigraphic sequence (Junction Formation, Devil River Volcanics Group, Haupiri Group) can be traced through 10 fault-bounded slices, which include a mélange-dominated slice (Balloon Mélange). These slices are the remnants of the accretionary prism; the stratigraphy within each slice generally youngs to the east, and the overall pattern of aging (based on relative age from provenance studies, sparse fossils, stratigraphic relations, and limited isotopic data) indicates that the older rocks generally dominate fault slices to the east, and younger rocks dominate fault slices to the west, delineating imbricate slices within an eastward-dipping subduction zone, in which the faults record a complex history of multi-phase reactivation. The Lockett Conglomerate is a ~500-m thick fan-delta conglomerate that is the preserved within one of the fault slices, where it is stratigraphically and structurally highest unit in the lower Takaka Terrane; it is also present as blocks within the Balloon Melange. The Lockett Conglomerate is marine at its base and transitions upwards to fluvial facies. The Lockett Conglomerate has previously been interpreted to result from erosion consequent on continued

  18. Mixing of methane and sulphate due to fluid flow in the Barbados accretionary prism

    SciTech Connect

    Laier, T. )

    1996-01-01

    Methane concentrations above background level in sulphate-containing (15 mmol/l) pore waters have been observed in the d6collement zone of the Barbados accretionary prism. The peak in methane concentration in the decollement was found at a number of sites by headspace analysis of cores retrieved during ODP Legs 110 156 at the toe of the accretionary prism. [delta][sup 13]C[sub 1] values between -22[per thousand] and -36[per thousand] indicate that methane oxidation occurs possibly due to sulphate reduction. Thus, the presence of both methane and sulphate at the same depths suggests mixing of fluids due to fluid flow. Fluid flow is also indicated by the distinct minima in chloride concentrations at the same depths. In the case of on-going methane oxidation, mixing of sulphate and methane fluids is anticipated to have occurred fairly recently. Sulphate concentration decreases only little with depth in the Pleistocene to lower Miocene sediments where TOC is very low, <0.2 %. Sulphate decreases more rapidly with depth in the Oligocene to Eocene sediments where numerous relatively thin turbidites occur. The turbidites have significantly higher TOC, 0.5-1.5 %, than the interbedded hemipelagic sediments, TOC <0.2 %. High methane concentrations were not found in any of the boreholes, but the trends in sulphate and methane in boreholes indicate that high methane concentrations exist in older sediments not reached by drilling. The decollement zone is composed of lower Miocene to upper Oligocene sediments near the toe of the prism, but deepens into stratigraphically lower sediments prism ward. Thus, methane originating from these older sediments may have been brought to shallower depths by active fluid flow in the decollement.

  19. Mixing of methane and sulphate due to fluid flow in the Barbados accretionary prism

    SciTech Connect

    Laier, T.

    1996-12-31

    Methane concentrations above background level in sulphate-containing (15 mmol/l) pore waters have been observed in the d6collement zone of the Barbados accretionary prism. The peak in methane concentration in the decollement was found at a number of sites by headspace analysis of cores retrieved during ODP Legs 110 & 156 at the toe of the accretionary prism. {delta}{sup 13}C{sub 1} values between -22{per_thousand} and -36{per_thousand} indicate that methane oxidation occurs possibly due to sulphate reduction. Thus, the presence of both methane and sulphate at the same depths suggests mixing of fluids due to fluid flow. Fluid flow is also indicated by the distinct minima in chloride concentrations at the same depths. In the case of on-going methane oxidation, mixing of sulphate and methane fluids is anticipated to have occurred fairly recently. Sulphate concentration decreases only little with depth in the Pleistocene to lower Miocene sediments where TOC is very low, <0.2 %. Sulphate decreases more rapidly with depth in the Oligocene to Eocene sediments where numerous relatively thin turbidites occur. The turbidites have significantly higher TOC, 0.5-1.5 %, than the interbedded hemipelagic sediments, TOC <0.2 %. High methane concentrations were not found in any of the boreholes, but the trends in sulphate and methane in boreholes indicate that high methane concentrations exist in older sediments not reached by drilling. The decollement zone is composed of lower Miocene to upper Oligocene sediments near the toe of the prism, but deepens into stratigraphically lower sediments prism ward. Thus, methane originating from these older sediments may have been brought to shallower depths by active fluid flow in the decollement.

  20. Local Seismicity Recorded by ChilePEPPER: Implications for Dynamic Accretionary Prism Response and Long-term Prism Evolution

    NASA Astrophysics Data System (ADS)

    de Moor, A.; Trehu, A. M.; Tryon, M. D.

    2015-12-01

    To investigate the dynamic response of the outer accretionary wedge updip from the patch of greatest slip during the Mw8.8 2010 Maule earthquake, 10 Ocean Bottom Seismometers (OBS) were deployed from May 2012 to March 2013 in a small array with an inter-instrument spacing of ~12 km . Nine instruments were recovered, with 4 recording data on 3 intermediate-band 3-component seismometers and a differential pressure gauge and 5 recording data from absolute pressure gauges. [note: All instruments were also equipped with a fluid flow meter sensitive to flow rates as low as 0.0001 cm/yr in or out of the sediments. However, no flow signal was detected.] Here we present hypocenters for 569 local events that have S-P times less than 17 seconds (i.e. within ~125 km of the array) using hand-picked arrival times and a 1D velocity model derived from a 2D seismic refraction profile through the region (Moscoso et al 2011, EPSL). We analyze the distribution of seismicity in the context of published slip models, ChilePEPPER high-resolution seismic reflection data, critical taper analysis done by Cubas et al 2013 (EPSL), and offshore gravity data. The data show distinct segmentation within the outer prism. The northern section of the study area is characterized by a lack of seismicity, accretion of nearly all incoming sediment and a prism at critical taper. In contrast, abundant seismicity, significant sediment underthrusting at the deformation front and a prism below critical taper angle characterize the southern part of the study area. Both coseismic slip and post-rupture local seismicity can be related to density anomalies within the upper plate as revealed by free air gravity data corrected for the effects of bathymetry and the subducting plate. [ChilePEPPER - Project Evaluating Prism Post-Earthquake Response

  1. Regional Variation of CH4 and N2 Production Processes in the Deep Aquifers of an Accretionary Prism

    PubMed Central

    Matsushita, Makoto; Ishikawa, Shugo; Nagai, Kazushige; Hirata, Yuichiro; Ozawa, Kunio; Mitsunobu, Satoshi; Kimura, Hiroyuki

    2016-01-01

    Accretionary prisms are mainly composed of ancient marine sediment scraped from the subducting oceanic plate at a convergent plate boundary. Large amounts of anaerobic groundwater and natural gas, mainly methane (CH4) and nitrogen gas (N2), are present in the deep aquifers associated with an accretionary prism; however, the origins of these gases are poorly understood. We herein revealed regional variations in CH4 and N2 production processes in deep aquifers in the accretionary prism in Southwest Japan, known as the Shimanto Belt. Stable carbon isotopic and microbiological analyses suggested that CH4 is produced through the non-biological thermal decomposition of organic matter in the deep aquifers in the coastal area near the convergent plate boundary, whereas a syntrophic consortium of hydrogen (H2)-producing fermentative bacteria and H2-utilizing methanogens contributes to the significant production of CH4 observed in deep aquifers in midland and mountainous areas associated with the accretionary prism. Our results also demonstrated that N2 production through the anaerobic oxidation of organic matter by denitrifying bacteria is particularly prevalent in deep aquifers in mountainous areas in which groundwater is affected by rainfall. PMID:27592518

  2. Earthquake faulting in subduction zones: insights from fault rocks in accretionary prisms

    NASA Astrophysics Data System (ADS)

    Ujiie, Kohtaro; Kimura, Gaku

    2014-12-01

    Subduction earthquakes on plate-boundary megathrusts accommodate most of the global seismic moment release, frequently resulting in devastating damage by ground shaking and tsunamis. As many earthquakes occur in deep-sea regions, the dynamics of earthquake faulting in subduction zones is poorly understood. However, the Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) and fault rock studies in accretionary prisms exhumed from source depths of subduction earthquakes have greatly improved our understanding of earthquake faulting in subduction zones. Here, we review key advances that have been made over the last decade in the studies of fault rocks and in laboratory experiments using fault zone materials, with a particular focus on the Nankai Trough subduction zone and its on-land analog, the Shimanto accretionary complex in Japan. New insights into earthquake faulting in subduction zones are summarized in terms of the following: (1) the occurrence of seismic slip along velocity-strengthening materials both at shallow and deep depths; (2) dynamic weakening of faults by melt lubrication and fluidization, and possible factors controlling coseismic deformation mechanisms; (3) fluid-rock interactions and mineralogical and geochemical changes during earthquakes; and (4) geological and experimental aspects of slow earthquakes.

  3. Fluid Overpressure and Connections to Seismicity, Cascadia Tertiary Accretionary Prism, Olympic Peninsula

    NASA Astrophysics Data System (ADS)

    Rotman, H.; Mattinson, C. G.

    2010-12-01

    Metamorphic dehydration reactions and fluid movement in accretionary prisms have been linked to the recently discovered episodic tremor and slip (ETS) earthquake events along subduction zones, but prior studies lack the detail to effectively test the hypothesis that fluid flow triggers ETS events. I conducted field work along a 52.5 km transect on the Olympic Peninsula metasedimentary accretionary prism of the Cascadia subduction zone, and collected approximately 40 representative samples of sandstone and mudrock that were buried to 6-15 km. This depth range intersects the 10-50 km depth range of ETS events. My objectives are to quantify the water flow recorded in rocks of the Olympic Peninsula via petrographic, whole rock, and isotopic analyses to test the prediction that water release increases at ~10 km depth, creating fluid overpressure needed to trigger seismicity. I calculated that on the Olympic Peninsula 1 km3 of 50% sandstone and 50% mudrock loses ~105 kg H2O/yr during burial from 6-14 km depth, comparable to the values expected from large-scale fluid budget models. Quartz veins that compose 0.5-1% of the Obstruction Peak site (~14 km burial depth) are important records of fluid flow quantity and origin. δ18O values of +11.8‰ to +15.2‰ indicate that vein H2O originated from metamorphic reactions. Flow recorded by 1 km3 of rock containing 0.5-1% quartz veins is >106 kg H2O/yr, comparable to the values 2 × 107 to 2 × 108 kg H2O/yr modeled at compositionally similar subduction zones to produce fluid overpressure conditions. I observed fibrous quartz veins, which also indicate fluid overpressure conditions were reached and support my H2O flow estimates. Therefore, Olympic Peninsula rocks at depths of ~10-14 km record dehydration and fluid overpressure large enough to trigger subduction zone seismicity.

  4. Variation in deformation of the South Panama Accretionary Prism: Response to oblique subduction and trench sediment variation

    NASA Astrophysics Data System (ADS)

    Mackay, Mary E.; Moore, Gregory F.

    1990-08-01

    Migrated single-channel seismic lines and Sea-MARC II side scan and bathymetry data document an active accretionary prism along the obliquely convergent margin of south Panama, a region previously believed to be a transform margin. The eastern flank of the Coiba Ridge is being subducted in this region, creating the requisite geometry for along-strike variation in trench sediment thickness and type. The regional east dip of the downgoing plate causes the depth of the oceanic crust along the trench to drop approximately 1800 m from west to east. In the western region of the study area the incoming sedimentary section consists of approximately 600 m of pelagic and hemipelagic sediments. A wedge of trench turbidites that overlies the incoming hemipelagic sediments thickens from less than 100 m in the western region to more than 900 m in the eastern region of the study area. The eastward increase in sediment thickness correlates with the following changes in the accretionary prism: (1) decrease in initial surface slope; (2) broadening of the inner trench slope; (3) increase in thrust spacing; (4) steepening of frontal thrusts; and (5) fold development. Each of the responses reflects, in varying degrees, the increase in volume and changing physical properties of the accreted material, as well as the changing shear strength of the décollement. The increase in overburden pressure and compaction in the deeper sediments, together with the change in lithology from oceanic to trenchfill sediments, should produce an eastward increase in sediment shear strength both within the wedge and along its base. Because the décollement will tend to form where the pore fluid pressure-overburden ratio is at a maximum, the shear strength within the wedge should increase relative to basal shear strength. Decreased surface slopes will result from the increasing contrast in shear strength between the wedge and its base.

  5. Fluid flow and mass flux determinations at vent sites on the Cascadia margin accretionary prism

    SciTech Connect

    Carson, B.; Strasser, J.C. ); Suess, E. )

    1990-06-10

    Fluid venting from the toe of the accretionary prism off Oregon was measured in situ during a series of dives with DSRV Alvin in 1987 and 1988. A benthic chamber was place over active vent sites to sequentially collect samples of venting fluids and to make direct measurements of discharge rates. Calibrated flow meter measurements and flow rates determined from dissolved methane transfer indicate that discharge from two vent sites, Alvin 1428 and Alvin 1900, ranges roughly between 100 and 500 l/m{sup 2}d with the most reliable estimates falling in the range of 125-150 l/m{sup 2}d. These rates imply subsurface advective flow on the order of 100 m/yr. Comparison of observed discharge rates with rates calculated for steady state expulsion supported by accretion-related compaction indicates that the observed flow is greater than predicted flow by several orders of magnitude. The disparity dictates that fluids are not derived locally, but are transported laterally within the prism, or that flow is not steady state and that individual vents are short-lived features in the ongoing accretion process.

  6. Understanding tectonic stress and rock strength in the Nankai Trough accretionary prism, offshore SW Japan

    NASA Astrophysics Data System (ADS)

    Huffman, Katelyn A.

    Understanding the orientation and magnitude of tectonic stress in active tectonic margins like subduction zones is important for understanding fault mechanics. In the Nankai Trough subduction zone, faults in the accretionary prism are thought to have historically slipped during or immediately following deep plate boundary earthquakes, often generating devastating tsunamis. I focus on quantifying stress at two locations of interest in the Nankai Trough accretionary prism, offshore Southwest Japan. I employ a method to constrain stress magnitude that combines observations of compressional borehole failure from logging-while-drilling resistivity-at-the-bit generated images (RAB) with estimates of rock strength and the relationship between tectonic stress and stress at the wall of a borehole. I use the method to constrain stress at Ocean Drilling Program (ODP) Site 808 and Integrated Ocean Drilling Program (IODP) Site C0002. At Site 808, I consider a range of parameters (assumed rock strength, friction coefficient, breakout width, and fluid pressure) in the method to constrain stress to explore uncertainty in stress magnitudes and discuss stress results in terms of the seismic cycle. I find a combination of increased fluid pressure and decreased friction along the frontal thrust or other weak faults could produce thrust-style failure, without the entire prism being at critical state failure, as other kinematic models of accretionary prism behavior during earthquakes imply. Rock strength is typically inferred using a failure criterion and unconfined compressive strength from empirical relations with P-wave velocity. I minimize uncertainty in rock strength by measuring rock strength in triaxial tests on Nankai core. I find strength of Nankai core is significantly less than empirical relations predict. I create a new empirical fit to our experiments and explore implications of this on stress magnitude estimates. I find using the new empirical fit can decrease stress

  7. Fluid expulsion sites on the Cascadia accretionary prism: mapping diagenetic deposits with processed GLORIA imagery

    USGS Publications Warehouse

    Carson, Bobb; Seke, Erol; Paskevich, Valerie F.; Holmes, Mark L.

    1994-01-01

     Point-discharge fluid expulsion on accretionary prisms is commonly indicated by diagenetic deposition of calcium carbonate cements and gas hydrates in near-surface (<10 m below seafloor; mbsf) hemipelagic sediment. The contrasting clastic and diagenetic lithologies should be apparent in side scan images. However, sonar also responds to variations in bottom slope, so unprocessed images mix topographic and lithologic information. We have processed GLORIA imagery from the Oregon continental margin to remove topographic effects. A synthetic side scan image was created initially from Sea Beam bathymetric data and then was subtracted iteratively from the original GLORIA data until topographic features disappeared. The residual image contains high-amplitude backscattering that we attribute to diagenetic deposits associated with fluid discharge, based on submersible mapping, Ocean Drilling Program drilling, and collected samples. Diagenetic deposits are concentrated (1) near an out-of-sequence thrust fault on the second ridge landward of the base of the continental slope, (2) along zones characterized by deep-seated strikeslip faults that cut transversely across the margin, and (3) in undeformed Cascadia Basin deposits which overlie incipient thrust faults seaward of the toe of the prism. There is no evidence of diagenetic deposition associated with the frontal thrust that rises from the dècollement. If the dècollement is an important aquifer, apparently the fluids are passed either to the strike-slip faults which intersect the dècollement or to the incipient faults in Cascadia Basin for expulsion. Diagenetic deposits seaward of the prism toe probably consist dominantly of gas hydrates

  8. Tectonic and Sedimentation Interactions in the East Caribbean Subduction Zone: AN Overview from the Orinoco Delta to the Barbados Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Deville, E.

    2011-12-01

    Recent marine geophysical acquisitions and piston-coring allow to better understand the close interactions between the sand-rich Orinoco turbidite system and the compressional structures of the Barbados prism. Because of the morphologic and tectonic control in the east-Caribbean active margin, the Orinoco turbiditic pattern system does not exhibit a classic fan geometry. The sea-floor geometry between the slope of the front of the Barbados prism and the slope of the South-American margin induces the convergence of the turbidite channels toward the abyssal plain, at the front of the accretionary prism. Also, whereas in most passive margins the turbidite systems are organized upstream to downstream as canyon, then channel-levee, then lobes, here, due to the tectonic control, the sedimentary system is organized as channel-levee, then canyons, then channelized lobes. At the edge of the Orinoco platform, the system has multiple sources with several distributaries and downward the channel courses are complex with frequent convergences or divergences that are emphasized by the effects of the undulating seafloor tectonic morphologies associated with active thrust tectonics and mud volcanism. On top of the accretionary prism, turbidite sediments are filling transported piggy-back basins whose timing of sedimentation vs. deformation is complex. Erosion processes are almost absent on the highly subsiding Orinoco platform and in the upper part of the turbidite system. Erosion processes develop mostly between 2000 and 4000 m of water depth, above the compressional structures of the Barbados prism (canyons up to 3 km wide and 300 m deep). In the abyssal plain, turbiditic channels develop on very long distance (> 1000 km) joining the mid-Atlantic channel (sourced mostly by the Amazon), filling several elongated basins corresponding to transform faults (notably the Barracuda Basin), and finally sourcing the Puerto-Rico trench, the deepest morphologic depression of this region

  9. Mechanical and hydraulic properties of subducted sediments, Nankai Trough accretionary prism: Effect of stress path

    NASA Astrophysics Data System (ADS)

    Kitajima, H.; Chester, F. M.; Biscontin, G.

    2010-12-01

    To understand the evolution of mechanical and hydraulic properties of sediments during burial, underthrusting, underplating, accretion, and exhumation within accertionary subduction zones, triaxial deformation experiments were conducted on consolidated sediment from the Nankai Trough sampled during the Integrated Ocean Drilling Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Stage 1 Expeditions. Samples of older, accretionary prism sediments at the forearc basin, underthrust slope sediments beneath the megasplay fault, and overthrust Upper Shikoku Basin sediments along the frontal thrust, were tested using different load paths. Specifically, isotropic loading, uniaxial strain loading, and triaxial compression (at constant confining pressure, Pc), undrained Pc reduction, drained Pc reduction, and triaxial unloading at constant Pc were employed. We find that all samples are overconsolidated and cemented. From the Pc-reduction stress paths, yield surfaces for the sediments are well described by the original Cam-Clay model and Coulomb failure criteria. Combined with results from the other load paths, we determine the yield surfaces for the sediments in situ, constrain the current stress state, and infer the relationship between consolidation state and deformation history including the effect of horizontal stress changes. Porosity evolution is relatively independent of stress path, and the sediment porosity decreases as the yield surface expands. In contrast, permeability evolution depends on the stress path and consolidation state, e.g., permeability reduction by shear-enhanced compaction occurs at a greater rate under triaxial-compression relative to uniaxial-strain and isotropic loading. Improved understanding of the evolution of hydromechanical properties for different load paths is necessary to accurately treat coupling of deformation and fluid flow in accretionary subduction zones.

  10. Hybrid granodiorites intruding the accretionary prism, Kodiak, Shumagin, and Sanak Islands, southwest Alaska

    NASA Astrophysics Data System (ADS)

    Hill, Malcolm; Morris, Julie; Whelan, Joseph

    1981-11-01

    A narrow belt of tonalite-granodiorite-granite plutons and batholiths intruded the accretionary prism in southwestern Alaska about 60 m.y. ago, simultaneously with plutonism over 100 km north along the main arc axis. The presence of metasedimentary xenoliths, kyanite, and garnet within the intrusions exposed on the Kodiak, Shumagin and Sanak islands establishes the presence of a crustal component. Extremely high values of δ18O, from +10.9 to +13.2 o/oo, require a crustal origin for much of the oxygen in the intrusions. Open-system alteration has disrupted whole-rock Rb-Sr systematics in some samples from the Sanak pluton and Shumagin batholith. Mineral isochrons using unaltered minerals yield an age of 58.7 ± 1.2 m.y. and 87Sr/86Sri = 0.70534 ± 10 for the Shumagin batholith, and ages of 62.7 ± 1.2 m.y. and 87Sr/86Sri = 0.70523 ± 14 for the Sanak pluton. Comparison of the isotopic data for the intrusions with those of sedimentary rocks in the Kodiak and Shumagin formations requires that a low-δ18O, low-87Sr/86Sr component be present as well. Mixing models combining 87Sr/87Sr and Sr contents of various kinds of mafic magmas with partial melts of metasedimentary wall rocks suggest that three types of mafic magmas can satisfactorily duplicate the oxygen isotope signature of the intrusions: (1) a mid ocean ridge (MORB)-like magma, (2) a magma derived by partial fusion of altered MORB, or (3) an arc basalt. The MORB model predicts abundances of Rb, Sr, Ba, and rare earth elements which are similar to those in the intrusions, while the altered MORB model does not. The arc magma model provides a better trace element match than the remelted MORB model, but is not as successful as the MORB model. These intrusions were preceded by a pulse of mafic to intermediate volcanism near or within the accretionary prism, recorded in the Paleocene Ghost Rocks Formation. This volcanism is probably the heat and mass source of the mafic component within the intrusions, and may be

  11. Estimation of slip parameters of a slip zone in the shallow portion of an accretionary prism

    NASA Astrophysics Data System (ADS)

    Hamada, Y.; Hirono, T.; Ishikawa, T.

    2010-12-01

    To evaluate the widely accepted scenario that a megasplay fault branching from a subduction boundary megathrust can contribute to the generation of devastating tsunamis, we investigated a major reverse fault in the Emi Group, Boso Peninsula, Japan, corresponding to the shallow portion of a thrust in an accretionary prism. We examined the rocks of the slip zone and the surrounding host rocks microscopically, and analyzed their trace elements and isotopes. On the basis of the fluid-mobile trace-element spectrum, which is sensitive to fluid-rock interaction at high temperatures, we estimated the paleo-thermal history of the slip zone. We discovered that the slip zone experienced frictional heating of >350 °C caused by high-velocity sliding. By numerical analysis of the frictional heating, we also estimated a large displacement of several meters along the fault at the shallow depth of approximately 1-2 km below the seafloor. Our results support the hypothesis that the megasplay fault plays an important role in the generation of huge tsunamis during subduction boundary earthquakes.

  12. Drilling into the deep interior of the Nankai accretionary prism: Preliminary results of IODP NanTroSEIZE Expedition 348

    NASA Astrophysics Data System (ADS)

    Tobin, H. J.; Hirose, T.; Saffer, D. M.; Toczko, S.; Maeda, L.

    2014-12-01

    International Ocean Discovery Program (IODP) Expedition 348, the latest advance of the NanTroSEIZE project, started on 13 September 2013 and was completed on 29 January 2014. During Expedition 348, the drilling vessel Chikyu advanced the ultra-deep riser hole at Site C0002, located 80 km offshore of the Kii Peninsula, from a depth of 860 meters below sea floor (mbsf) to 3058.5 mbsf, the world record for the deepest scientific ocean drilling, and cased it for future deepening. The drilling operation successfully obtained data on formation physical properties from logging while drilling (LWD) tools, as well as from lithological analyses of cuttings and core from the interior of the active accretionary prism at the Nankai Trough. IODP Site C0002 is the currently only borehole to access the deep interior of an active convergent margin. Preliminary scientific results of Expedition 348 are as follows: (1) Fine-grained turbiditic mudstones with coarser silty and sandy interbeds, exhibiting steep dips (between ~60 and 90 degrees) are predominant in the prism down to ~3000 mbsf. The biostratigraphic age of the sediments in the lowermost part of the hole is thought to be 9-11 Ma, with an assumed age of accretion of 3-5 Ma. (2) Slickenlined surfaces, deformation bands and mineral veins are present throughout the drilled interval, while well-developed scaly clay fabrics are increasingly observed below ~2200 mbsf. A substantial fault zone with well-developed foliation was successfully cored from the deep interior of the prism at ~2205 mbsf. (3) Porosity generally decreases from ~60% to ~20% from the seafloor to 3000 mbsf. However, physical properties including grain density, electrical conductivity and P-wave velocity suggest fairly homogeneous properties in the interior of the prism between ~2000 and 3000 mbsf. (4) Mud gas analysis during the riser drilling indicates that a source of methane gas shifts from microbial origin to thermogenic at around 2325 mbsf. (5) The maximum

  13. Recognition and implication for two stage layer-parallel faults in accretionary prisms onland and under the sea

    NASA Astrophysics Data System (ADS)

    Michiguchi, Y.; Ogawa, Y.

    2006-12-01

    The Nishizaki Formation of the Miura Group in the southernmost Boso Peninsula, southeast of Tokyo, close to the only trench-trench-trench (TTT)-type triple junction, is thought to be an accretionary prism from the late Miocene to early Pliocene, having many initial deformation structures without strong metamorphism. Layer- parallel faults composed of black seams of a few mm thick in the upper alternating beds of sandstone and siltstone are developed ubiquitously in the Nishizaki Formation, crosscutting late faults of both normal and thrust senses, suggesting to form before lithification. By SEM and thin section observation the black seam is characterized not by grain-crushing but by rearrangement of mica-clay minerals. In additon, the mica-clay minerals array at least 2 directions. Such features are similar to the black seam was commonly observed in the samples from the Nankai Trough prism collected by Sinkai 6500 of JAMSTEC. XRD analysis indicates the mica-clay minerals in black seams for both the Nishizaki and Nankai are composed of smectite and illite. Some black seams occurred parallel to bedding plane immediately after sedimentation, because they are cut by vein structure and the grains on the boundary flow ductility, probably during submarine sliding. This kind of faults is transitional to either normal or thrust faults laterally, most probably similar to the based slip plane of land sliding. However, there are at least two stages layer-parallel faults. One is submarine sliding stage before accretion, that is gravitation, another is thrust fault stage during accretion, that is tectonic.

  14. Relationship between tectonics, argilokinetic structures, and environmental patterns at the south boundary of the Barbados accretionary prism

    SciTech Connect

    Griboulard, R.; Bobier, C.; Faugeres, J.C.; Gonthier, E.

    1993-02-01

    Recent studies have been carried out on limited sectors of the South Barbados accretionary prism. They are supported by SeaBeam map analysis, high resolution seismic data, time-lapse and video camera tracks, numerous cores and Side Scan Sonar data. The analysis of these data point out numerous evidences of an active and present tectonic activity on the southern part of this domain. The development of very large indurate sea-bottoms on which deep-sea communities frequently occur and where we can observe some [open quotes]sigmoidal[close quotes] features and network of conjugate fractures which suggest the presence of shear deformation zone. In addition, tracks of important and probably deep faults extend across both soft and indurated bottom sediments. The regional morphological anomalies are comparable to analogical deformation model for a thick cover sticking out of its sub-stratum and the tectonic activity is closely associated to the presence of deep dysharmonic levels which control, obviously, an important clay-diapirism. This is an effect of both the structural location of this region, at the junction of three lithospheric plates (Caribbean, Atlantic, and South-American) and paleogeographical and sedimentological changes since Neogene time, with the very important terrigeneous supplies coming from the Orinoco River. Consequently, the main deformations that we observed in this region are rather under influence of shearing and transpressive than compressive movements.

  15. Structural characteristics of shallowly buried accretionary prism: Rapidly uplifted Neogene accreted sediments on the Miura-Boso Peninsula, central Japan

    NASA Astrophysics Data System (ADS)

    Yamamoto, Y.; Mukoyoshi, H.; Ogawa, Y.

    2005-10-01

    The upper Miocene Misaki and Nishizaki formations on the Miura and Boso peninsulas in central Japan preserve the deformation features of an off-scraped accretionary prism. The spatial distribution, geometry, and style of accretion-related deformation with paleotemperature and burial depth estimation are elucidated in this study. The deformation structures and textures are similar to those of modern accretionary prisms. The low maximum paleotemperature (<50°C) and high preserved porosity of the sediments (30-50%) imply a maximum burial depth of less than 1000 m. On the basis of the mode of deformation, this off-scraped body is divided into an imbricate thrust, a thrust unit, and an upper coherent unit in ascending order. The imbricate thrust corresponds to a branch from the basal décollement zone and is subdivided into a brecciated zone, a main gouge zone, and a shear band zone. The thrust unit hosts a concentration of thrust systems that form various orders of duplex structures, while the upper coherent unit is characterized by gravitational instability- and earthquake-induced deformation without thrust faulting. The duplex distribution, shear strain, and fluid migration associated with the off-scraping processes are clearly localized within the imbricate thrust and thrust unit. This accretion-related deformation occurred before lithification of the sediment and under high fluid pressure induced by shear deformation, thickening of the sedimentary sequence, and earthquake-induced liquefaction. These processes are inferred to control the effect on the mode of deformation and the location of thrusting during early deformation of the accretionary prism.

  16. Consolidation patterns during initiation and evolution of a plate-boundary decollement zone: northern Barbados accretionary prism

    USGS Publications Warehouse

    Moore, J.C.; Klaus, A.; Bangs, N.L.; Bekins, B.; Bucker, C.J.; Bruckmann, W.; Erickson, S.N.; Hansen, O.; Horton, T.; Ireland, P.; Major, C.O.; Moore, G.F.; Peacock, S.; Saito, S.; Screaton, E.J.; Shimeld, J.W.; Stauffer, P.H.; Taymaz, T.; Teas, P.A.; Tokunaga, T.

    1998-01-01

    Borehole logs from the northern Barbados accretionary prism show that the plate-boundary decollement initiates in a low-density radiolarian claystone. With continued thrusting, the decollement zone consolidates, but in a patchy manner. The logs calibrate a three-dimensional seismic reflection image of the decollement zone and indicate which portions are of low density and enriched in fluid, and which portions have consolidated. The seismic image demonstrates that an underconsolidated patch of the decollement zone connects to a fluid-rich conduit extending down the decollement surface. Fluid migration up this conduit probably supports the open pore structure in the underconsolidated patch.

  17. Structure and clay mineralogy: borehole images, log interpretation and sample analyses at Site C0002 Nankai Trough accretionary prism

    NASA Astrophysics Data System (ADS)

    Jurado, Maria Jose; Schleicher, Anja

    2015-04-01

    Our research focused on the characterization of fracture and fault structures from the deep Nankai Trough accretionary prism in Japan. Logging Data and cuttings samples from the two most recent International Ocean Discovery Program (IODP) Expeditions 338 and 348 of the NanTroSEIZE project were analyzed by Logging While Drilling (LWD) oriented images, geophysical logs and clay mineralogy. Both expeditions took place at Site C0002, but whereas Hole C0002F (Expedition 338) was drilled down to 2004.5 mbsf, Hole C0002N and C0002P (Expedition 348) reached a depth of 2325.5 mbsf and 3058.8 mbsf respectively. The structural interpretation of borehole imaging data illustrates the deformation within the fractured and faulted sections of the accretionary prism. All drill holes show distinct areas of intense fracturing and faulting within a very clay-dominated lithology. Here, smectite and illite are the most common clay minerals, but the properties and the role they may play in influencing the fractures, faults and folds in the accretionary prism is still not well understood. When comparing clay mineralogy and fracture/fault areas in hole C0002F (Expedition 338), a trend in the abundance of illite and smectite, and in particular the swelling behavior of smectite is recognizable. In general, the log data provided a good correlation with the actual mineralogy and the relative abundance of clay. Ongoing postcruise preliminary research on hole C0002 N and C0002P (Expedition 348) should confirm these results. The relationship between fracture and fault structures and the changes in clay mineralogy could be explained by the deformation of specific areas with different compaction features, fluid-rock interaction processes, but could also be related to beginning diagenetic processes related to depth. Our results show the integration of logging data and cutting sample analyses as a valuable tool for characterization of petrophysical and mineralogical changes of the structures of the

  18. Fluid circulation in the depths of accretionary prisms: an example of the Shimanto Belt, Kyushu, Japan

    NASA Astrophysics Data System (ADS)

    Raimbourg, Hugues; Vacelet, Maxime; Ramboz, Claire; Famin, Vincent; Augier, Romain; Palazzin, Giulia; Yamaguchi, Asuka; Kimura, Gaku

    2015-08-01

    Accretionary prisms constitute ideal targets to study fluid circulation and fluid-rock interactions at depths beyond the reach of active margin deep drilling. The highest-grade rocks from the Shimanto Belt on Kyushu were buried under 3-5 kbars at ~ 300°C (Toriumi and Teruya, 1988). They contain abundant quartz veins, formed throughout burial and exhumation and variably affected by brittle and ductile deformation. Cathodoluminescence (CL) reveals the existence of two distinct types of quartz, characterized by a blue and brown color, respectively. CL-blue quartz fills macro-veins (width ≥ 10μm), while CL-brown quartz is present in micro-veins (width ~ 1 - 10μm) and ductilely recrystallized domains. On the basis of microstructures, the fluids associated with the CL-blue and CL-brown quartz are interpreted as "external" and "local", respectively. Quartz growth rims of alternating CL colors as well as mutually cross-cutting veins show that the two fluids cyclically wetted the host rock. From fluid inclusions analysis, the fluid associated with CL-blue quartz has a salinity similar to seawater, while the fluid associated with CL-brown quartz is less saline. In addition, CL-blue quartz is richer in aluminum than the CL-brown one. In contrast to the salinity/aluminum signature, the δ18O isotopic signature of both quartz types is similar and buffered by host rock. The difference between the preservation of the salinity signature of the fluid and the loss of its δ18O signature is explained by quicker exchange kinetics and larger host rock buffering capacity for isotopic reequilibration. The "local" fluid, associated with CL-brown quartz, reflects the dilution of pore water by the pure water produced by prograde dehydration reactions of clay minerals. The "external" fluid associated with CL-blue quartz is interpreted as seawater or pore water from shallow (depth < 1-2 km below seafloor) sediments. We propose that downward percolation of shallow water to depths ~ 10 km

  19. Observations and Rock Analyses in a Kumano Mud Volcano in Nankai Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Morita, S.; Aoike, K.; Sawada, T.; Ashi, J.; Gulick, S. P.; Flemings, P. B.; Kuramoto, S.; Saito, S.; Mikada, H.; Kinoshita, M.

    2002-12-01

    Kumano Basin is a forearc basin on the eastern Nankai Accretionary Prism off southwest Japan. Recent bathymetric survey showed existence of small knolls in the Kumano Basin. Submersible and ROV dives, sidescan sonar and deep-towed camera investigations revealed so far that at least five of the small knolls are mud volcanoes erupted on the Kumano Basin floor. In June and August, 2002, Dive 677 and 681 by submersible SHINKAI 6500 (YK02-02: R/V Yokosuka) and Dive 267 by ROV KAIKO (KR02-10: R/V Kairei) were performed in one of the mud volcanoes, Kumano Knoll No.4, which is 100 m high and 800 m in diameter at the foot of the knoll. The knoll has a plateau of about 300 m diameter on the top, which shows bumpy surface where there are waves, steps and craters of several meters in diameter. The craters imply active or dead cold seeps and are occasionally accompanied by Calyptogena colonies. The plateau is mostly covered with mud. Rock gravels and boulders were observed mainly on outer slope of the knoll. Sidescan sonar and subbottom profiler data by KAIKO system show marked contrasts in sonic reflectivity and penetration between the Kumano Knoll No.4 and the Kumano Basin floor. The high sonic reflectivity and the low penetration on the knoll indicate that main body of the knoll is composed of clastic ejecta as a mud volcano. On the Kumano Knoll No.4, the dives obtained semi-consolidated mudstone, mud breccia, and biotite arkose sandstone. Chronological analysis on nannofossil indicates the sedimentary rocks are in the late Early Miocene through the Middle Miocene. According to this age and geological information on land, it is likely that the sedimentary rocks on the knoll were originally deposited at the beginning of formation of the Kumano Basin. Porosity of these sedimentary rocks is very low (< 18 %). Some mud breccias contain calcite veins that cut the angular mud gravels. These features lead to finding processes until when the sedimentary rocks reached to the seafloor

  20. Rates of fluid expulsion across the northern Cascadia accretionary prism: Constraints from new heat flow and multichannel seismic reflection data

    SciTech Connect

    Davis, E.E.; Hyndman, R.D. ); Villinger, H. )

    1990-06-10

    One hundred and ten closely spaced probe heat flwo measurements provide new constraints on the thermal regime of the northern Cascadia accretionary prism off Vancouver Island. Complementary heat flow values have been obtained from the depth of a bottom-simulating seismic reflector (BSR) that is interpreted to mark the thermally controlled base of a methane hydrate layer. The only local heat flow variations observed are associated with a sediment slump that is seen in SeaMARC II acoustic images and with the outcrop of several major thrust faults. Fluid expulsion resulting from the dewatering of the prism sediments appears to occur regionally in the 10-20-km-wide zone landward of the deformation front. In this area there is a significant disagreement between the probe and BSR heat flow estimates (roughly 30%) that can be explained by a regionally uniform vertical fluid flow at a rate of about 8 {times} 10{sup {minus}10} m/s. This is in good agreement with the estimated fluid expulsin rate required by the decrease in porosity landward of the deformation front, as estimated from the increase in seismic velocities derived from multichannel reflection data. The heat flow in Cascadia Basin seaward of the deformation front is in excellent agreement with that predicted by cooling plate models. Landward, there is a regional trend of decreasing heat flow across the accretionary prism, which is consistent with a model of simple tectonic thickening. Temperatures at the interface between the prism and the oceanic crust continue to increase landward, and reach 400-450 C beneath the middle to inner continental shelf. Initiation of megathrust earthquake failure along the main subduction thrust may be thus restricted by the high temperatures to the zone beneath the continental slope and outer shelf.

  1. Low frequency tremors in the Tonankai accretionary prism, triggered by the 2011 Tohoku-Oki earthquake

    NASA Astrophysics Data System (ADS)

    To, A.; Obana, K.; Takahashi, N.; Fukao, Y.

    2012-12-01

    There have been many reports of triggered tremors and micro-earthquakes, by the 2011 Tohoku-Oki earthquake, most of which are based on land observations. Here, we report that numerous low frequency tremors are recorded by broadband ocean-bottom seismographs of DONET, a network of cabled observatory systems deployed in the Tonankai accretionary prism of the Nankai trough. Ten stations were in operation at the time of the earthquake. The tremors are observed at five of the stations, which are located on the landward slope of the Nankai trough. On the other hand, the signals are weak at stations near the coast, which are placed on the Kumano Forarc basin. The tremors are dominant in a frequency range of 1-10Hz. Their duration ranges from tens of seconds to a few minutes. More than 20 events per hour can be detected in the first few days after the earthquake. The activity continues about three weeks with a decrease in the frequency of occurrence. An intriguing feature of the observed tremors is that some of them have a very low frequency (VLF) component, most clearly visible between 0.02 and 0.05 Hz. We found 74 such events within 5 days after the great earthquake. For each event, the VLF signal is detected only at one station in contrast to the high frequency signal (2-8Hz), which can be observed at more than a few stations. We estimated the source location of the VLF events, by measuring the onset of envelope seismograms constructed from the high frequency (2-8Hz) horizontal component. Due to the unclear onset and the limited number of observable stations per event, the individual events were located with large location errors. Therefore, we assumed that 11 of the events, whose VLF waveforms are similar to each other with high correlation coefficient (> 0.92), are co-located. The measured travel times for the 11 events are compared and some outliers were discarded. We grid-searched through a 3-D S-wave velocity model for the event location, which minimizes the travel

  2. Resonant seismic and microseismic ground motion of the Cascadia subduction zone accretionary prism and implications for seismic velocity

    NASA Astrophysics Data System (ADS)

    Davis, Earl E.; Heesemann, Martin

    2015-02-01

    Seafloor pressure and seismic observations have been made along a transect of sites off southwestern Canada using connections to the NEPTUNE Canada cabled network beginning in the fall of 2009. A comparison of the vertical ground motion response to oceanographic and seismic loading at a site on the outer Cascadia subduction zone accretionary prism to that at a site on the adjacent Juan de Fuca Plate shows generally stronger ground motion at the prism site across the full bandwidths of infragravity waves and microseisms and a strong sharp peak in the relative response at a period of 9 s. This peak is seen in the response to loading by local storm waves and dispersive swell sequences, as well as in the average response to storm- and swell-generated pressure fluctuations averaged over long periods of time. Tuned response to teleseismic surface waves is also seen at the same frequency. We infer that this behavior results from quarter-wavelength harmonic resonance of the prism, with the two-way travel time of compressional waves between the seafloor and underlying igneous crust being one half the resonance period. The consistency of the anomalous spectral peak from year to year at this particular site suggests that the behavior might be used to track small (≈1%) changes in the vertical seismic velocity of the prism if variations related to strain or pore fluid pressure changes through a subduction thrust earthquake cycle were to occur.

  3. Provenance analysis of the Miocene accretionary prism of the Hengchun Peninsula, southern Taiwan, and regional geological significance

    NASA Astrophysics Data System (ADS)

    Zhang, Xinchang; Yan, Yi; Huang, Chi-Yue; Chen, Duofu; Shan, Yehua; Lan, Qin; Chen, Wenhuang; Yu, Mengming

    2014-05-01

    Petrographic analysis, detrital zircon U-Pb geochronology and Neodymium isotope are applied to the Middle-Late Miocene turbidite sequences in the Hengchun accretionary prism, southern Taiwan, to constrain the provenance and nature of sedimentation in the Manila subduction system. Both petrographic study and detrital zircon U-Pb ages show that the Middle-Late Miocene turbidite sequences were primarily derived from Mesozoic granites and volcanic rocks of the Cathaysian Block in SE China, which were transported southeastward via rivers like Minjiang and Jiulongjiang to the Taiwan area. This conclusion is further supported by Nd isotope analyses of shales intercalated within sandstone sequences showing negative ɛNd values (-13.3 to -10.5) of a continental origin. During the Late Miocene when global sea-level fell significantly, the SE China coastline shifted seaward to the eastern part of the present Taiwan Strait, which would have facilitated these continent-derived sediments being transported southeastward to the shelf-upper slope of the Chinese continental margin. These turbidite sequences were then deformed and accreted into the accretionary prism of the Hengchun Peninsula when the South China Sea oceanic lithosphere subducted eastward beneath the Philippine Sea Plate in the Late Miocene. Our study suggests that sedimentary deposition of the turbidite sequences in the Hengchun Peninsula could be strongly controlled by different river system supply, submarine channeling transport and fluctuations of sea-level.

  4. Seismic structure of the southern Cascadia subduction zone and accretionary prism north of the Mendocino triple junction

    USGS Publications Warehouse

    Gulick, S.P.S.; Meltzer, A.M.; Clarke, S.H., Jr.

    1998-01-01

    Four multichannel-seismic reflection profiles, collected as part of the Mendocino triple junction seismic experiment, image the toe of the southern Cascadia accretionary prism. Today, 250-600 m of sediment is subducting with the Gorda plate, and 1500-3200 m is accreting to the northern California margin. Faults imaged west and east of the deformation front show mixed structural vergence. A north-south trending, 20 km long portion of the central margin is landward vergent for the outer 6-8 km of the toe of the prism. This region of landward vergence exhibits no frontal thrust, is unusually steep and narrow, and is likely caused by a seaward-dipping backstop close to the deformation front. The lack of margin-wide preferred seaward vergence and wedge-taper analysis suggests the prism has low basal shear stress. The three southern lines image wedge-shaped fragments of oceanic crust 1.1-7.3 km in width and 250-700 m thick near the deformation front. These wedges suggest shortening and thickening of the upper oceanic crust. Discontinuities in the seafloor west of the prism provide evidence for mass wasting in the form of slump blocks and debris fans. The southernmost profile extends 75 km west of the prism imaging numerous faults that offset both the Gorda basin oceanic crust and overlying sediments. These high-angle faults, bounding basement highs, are interpreted as strike-slip faults reactivating structures originally formed at the spreading ridge. Northeast or northwest trending strike-slip faults within the basin are consistent with published focal mechanism solutions and are likely caused by north-south Gorda-Pacific plate convergence. Copyright 1998 by the American Geophysical Union.

  5. Seismic structure of the southern Cascadia subduction zone and accretionary prism north of the Mendocino triple junction

    NASA Astrophysics Data System (ADS)

    Gulick, Sean P. S.; Meltzer, Anne M.; Clarke, Samuel H., Jr.

    1998-11-01

    Four multichannel-seismic reflection profiles, collected as part of the Mendocino triple junction seismic experiment, image the toe of the southern Cascadia accretionary prism. Today, 250-600 m of sediment is subducting with the Gorda plate, and 1500-3200 m is accreting to the northern California margin. Faults imaged west and east of the deformation front show mixed structural vergence. A north-south trending, 20 km long portion of the central margin is landward vergent for the outer 6-8 km of the toe of the prism. This region of landward vergence exhibits no frontal thrust, is unusually steep and narrow, and is likely caused by a seaward-dipping backstop close to the deformation front. The lack of margin-wide preferred seaward vergence and wedge-taper analysis suggests the prism has low basal shear stress. The three southern lines image wedge-shaped fragments of oceanic crust 1.1-7.3 km in width and 250-700 m thick near the deformation front. These wedges suggest shortening and thickening of the upper oceanic crust. Discontinuities in the seafloor west of the prism provide evidence for mass wasting in the form of slump blocks and debris fans. The southernmost profile extends 75 km west of the prism imaging numerous faults that offset both the Gorda basin oceanic crust and overlying sediments. These high-angle faults, bounding basement highs, are interpreted as strike-slip faults reactivating structures originally formed at the spreading ridge. Northeast or northwest trending strike-slip faults within the basin are consistent with published focal mechanism solutions and are likely caused by north-south Gorda-Pacific plate convergence.

  6. The 50 Ma granodiorite of the eastern Gulf of Alaska - Melting in an accretionary prism in the forearc

    NASA Astrophysics Data System (ADS)

    Barker, Fred; Farmer, G. L.; Ayuso, R. A.; Plafker, George; Lull, J. S.

    1992-05-01

    The paper addresses the generation of granitic rocks by the melting of flyschoid sediments in an accretionary prism as part of an investigation of 50-Ma silicic igneous rocks in the Gulf of Alaska, near Cordova, Alaska. Three intrusive bodies exhibiting a range of chemical and initial isotopic compositions were chosen: the McKinley Peak, Rude River, and Sheep Bay plutons. The present chemical data, modeling, and comparison with melting experiments of graywacke by Conrad et al. (1988) indicate that the granodiorite originated by large fractions (65-90 percent) of melting of the Orca Group graywacke and argillite. Plagioclase, pyroxene, and biotite were residual to melting at about 850-950 C and at low H2O activities. It is suggested that the distinct chemical and isotopic compositions of the McKinley Peak pluton result from variations in the character of the flysch at depth in the prism, rather than from mixing between melts of the flysch and mafic magmas injected into the prism itself.

  7. Accumulation of an earthquake-induced extremely turbid layer in a terminal basin of the Nankai accretionary prism

    NASA Astrophysics Data System (ADS)

    Ashi, Juichiro; Sawada, Ritsuko; Omura, Akiko; Ikehara, Ken

    2014-12-01

    Seismic shaking is a major trigger for sediment redistribution in subduction zones, and clouds of dilute suspended sediment have been reported in association with large earthquakes. Dive observations in a basin on the slope of the central Nankai accretionary prism soon after the 2004 off-Kii Peninsula earthquakes documented a layer of suspended sediment with extremely high turbidity. We estimated the thickness of this bottom turbid layer to be more than 2.5 m by comparison of seafloor depths between surveys in 2004 and 2010 and about 2.6 m from instrumental evidence involving the submersion of a heat-flow probe. A high-resolution subbottom profiling survey across the basin revealed acoustically transparent layers thicker than 2 m. Because the slope basin is a terminal basin completely enclosed by topographic highs, we examined the possibility that the uppermost transparent layer was deposited as a consequence of the 2004 earthquakes. Considering the sediment source area and the volume of the basin fills, the mobilization and redeposition of thin surface sediments on the prism slope can account for the volume of the transparent layer. We conclude that the 2004 earthquakes caused widespread disturbance of the prism slope and concentrated surface sediments in this terminal basin. Our results emphasize the utility of a terminal basin in a subduction zone as an earthquake recorder.

  8. Approximate General Coulomb Model for Accretionary Prisms: An Integrated Study of the Kumano Transect, Nankai Subduction Zone, Southwest Japan

    NASA Astrophysics Data System (ADS)

    Skarbek, Rob; Ikari, Matt; Hüpers, Andre; Rempel, Alan; Wilson, Dean; Kitajima, Hiroko

    2014-05-01

    In accretionary wedges, the mechanical and hydrologic properties along splay faults and the plate boundary fault at the base of the wedge are intimately related to properties within the wedge itself, as well as to sedimentation and/or mass wasting at the wedge surface, and accretionary flux at the wedge toe; Coulomb wedge theories tie these processes together and have been successful in their application to convergent margins. Most such theories assume for the sake of simplicity that mechanical parameters (e.g. bulk density, compressibility, frictional strength) and pore pressure are constant throughout the overlying wedge. However, the values of these parameters must necessarily change with depth and distance from the trench. Here, we derive a model for a fully general Coulomb wedge, parameterized using data specific to the Kumano transect at Nankai, to better understand the location of the basal plate interface and the properties of material composing an actively accretionary prism. We use shear strength data collected for incoming sediments at Integrated Ocean Drilling Program Site C0011 of the NanTroSEIZE project to parameterize the wedge's coefficient of friction. Preliminary results of models where the friction coefficient of the wedge decreases with depth, with other parameters constant and zero cohesion, indicate that including depth dependent frictional strength in the wedge decreases the taper angle of the wedge, with the effect becoming more pronounced with distance from the trench. This model will be further refined by including seismically and numerically determined spatial variations in fluid pressure within the wedge, as well as detailed locations of the upper and basal wedge surfaces along the Kumano transect determined from 3-D seismic data.

  9. Small size very low frequency earthquakes in the Nankai accretionary prism, following the 2011 Tohoku-Oki earthquake

    NASA Astrophysics Data System (ADS)

    To, Akiko; Obana, Koichiro; Sugioka, Hiroko; Araki, Eiichiro; Takahashi, Narumi; Fukao, Yoshio

    2015-08-01

    A large number of shallow low frequency events were recorded after the 2011 Mw 9.0 Tohoku-oki earthquake by the cabled network of broadband ocean bottom seismometers (DONET) deployed in the eastern part of the Nankai trough. This low frequency event activity was intense for the first few days after the great earthquake and gradually decreased. Signals of the events are most clearly visible at the frequency range around 2-8 Hz. Some of the events are accompanied by a very long frequency (VLF) signal, which is clearly observed at around 0.02-0.05 Hz. The magnitude and source duration estimated by waveform analysis for one of the largest very low frequency earthquakes (VLFEs) was 3.0-3.5 and 17 s. This source duration is extremely long compared to ordinary earthquakes of comparable magnitude. These newly detected VLFEs are likely to be normal fault earthquakes located at shallow depths within the accretionary prism, in contrast to the previously reported VLFEs that were explained by a low angle thrusting along the decollement zone. On the other hand, the low frequency events with no clear VLF signal were previously regarded as being low frequency tremors (LFTs). We show that events with and without the VLF signal likely represent the same phenomenon, and the VLF signal is only observed when a large magnitude event occurs near the station. The waveforms of VLFEs are characterized by the coexistence of long source duration and high-frequency radiation of signals, and such features were previously explained by the co-occurrence of shear failure and hydrofractures under the influence of fluid brought into the decollement zone. Our result indicates that the stress state and the mechanical environment, which promote the occurrence of VLFEs, exist not only along the decollement zone but also in the shallower part of the accretionary prism.

  10. New insights into the active deformation of accretionary prisms: examples from the Western Makran, Iran

    NASA Astrophysics Data System (ADS)

    Penney, Camilla; Copley, Alex; Oveisi, Benham

    2016-04-01

    The Makran subduction zone, along the southern coasts of Iran and Pakistan, hosts one of the largest exposed accretionary wedges in the world. The western Makran has been characterised by a lack of shallow and thrust seismicity in both the instrumental and historical periods. The Mw 6.1 2013 Minab earthquake thus provides a rare opportunity to study the deformation of the accretionary wedge in the transition region between continent-continent collision, in the Zagros, and oceanic subduction, in the Makran. We study the source parameters and slip distribution of this earthquake using seismology, geodesy and field observations. We observe left-lateral strike-slip motion on a fault striking ENE-WSW; approximately perpendicular to the faults of the Minab-Zendan-Palami fault zone, the main structure previously thought to accommodate the right-lateral shear between the Zagros and the Makran. The fault that ruptured in 2013 is one of a series of approximately E-W striking left-lateral faults visible in the geology and geomorphology. These accommodate a velocity field equivalent to right-lateral shear on N-S striking planes by clockwise rotations about vertical axes. The longitudinal range of shear in the western Makran is likely to be controlled by the distance over which the underthrusting Arabian lithosphere deepens in the transition from continent-continent collision to oceanic subduction. The lack of observed megathrust seismicity in the western Makran has led to assertions that the convergence in this region may be aseismic, in contrast to the eastern Makran, which experienced an Mw8.1 earthquake in 1945. The right-lateral Sistan Suture Zone, which runs ~N-S along the Iran-Afghanistan border to the north of the Makran, appears to separate these regimes. However, right-lateral faulting is not observed south of ~27°N, within the wedge. The Minab earthquake and the 2013 Balochistan earthquake show that the Makran accretionary wedge is dominated by strike-slip faulting

  11. The effect of fault-bend folding on seismic velocity in the marginal ridge of accretionary prisms

    USGS Publications Warehouse

    Cai, Y.; Wang, Chun-Yong; Hwang, W.-t.; Cochrane, G.R.

    1995-01-01

    Fluid venting in accretionary prisms, which feeds chemosynthetic biological communities, occurs mostly on the marginal thrust ridge. New seismic data for the marginal ridge of the Cascadia prism show significantly lower velocity than that in the adjacent oceanic basin and place important constraints on the interpretations of why fluid venting occurs mostly on the marginal ridge. We employed a finite-element method to analyze a typical fault-bend folding model to explain the phenomenon. The fault in the model is simulated by contact elements. The elements are characterized not only by finite sliding along a slide line, but also by elastoplastic deformation. We present the results of a stress analysis which show that the marginal ridge is under subhorizontal extension and the frontal thrust is under compression. This state of stress favors the growth of tensile cracks in the marginal ridge, facilitates fluid flow and reduces seismic velocities therein; on the other hand, it may close fluid pathways along the frontal thrust and divert fluid flow to the marginal ridge. ?? 1995 Birkha??user Verlag.

  12. Permeability of Silty Claystone and Turbidite Samples from IODP Expedition 348, Hole C0002P, Nankai Trough Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Song, C.; Underwood, M.

    2014-12-01

    One of the main objectives of IODP Expedition 348 was to characterize the variations of lithology and structure with depth in the interior of the Nankai Trough accretionary complex beneath the Kumano forearc basin (offshore SW Japan). Six cores were recovered from Hole C0002P between 2163 and 2218 mbsf. Four whole-round (WR) specimens from depths of 2174.98 to 2209.64 mbsf were tested for constant-flow permeability with a focus on thin interbeds of silty claystone and fine-grained turbidites. Samples are from lithostratigraphic Unit V (accreted trench or Shikoku Basin hemipelagic deposits). Coarser interbeds are important for assessing the prospects of flow through stratigraphic conduits. Our primary objective is to better understand how hydrogeologic properties of different lithologies respond to deformation within the accretionary prism. Equipment for permeability tests consists of a withdrawal-infuse syringe pump to simultaneously inject and extract pore fluid from the top and bottom of the specimen to generate hydraulic head difference. Specimens were trimmed for tests in both vertical direction (along-core) and horizontal direction (cross-core) with the diameter of 3.8 cm (1.5 in). The isotropic effective stress is set at 0.55 MPa. The WR specimens are heterogeneous. The major lithology is silty claystone to fine-grained silty claystone. Some intervals contain thin (~1.3 cm) oblique sandy layers and black organic bands. Bedding is steep to vertical (~70-80˚). One goal is to determine how this lithologic variability affects the anisotropy of permeability. Environmental SEM was used to image the cores (in multiple directions) to evaluate the relation between sediment microstructure and anisotropy of permeability.

  13. A lithium isotopic study of sub-greenschist to greenschist facies metamorphism in an accretionary prism, New Zealand

    NASA Astrophysics Data System (ADS)

    Qiu, Lin; Rudnick, Roberta L.; Ague, Jay J.; McDonough, William F.

    2011-01-01

    To investigate the behavior of Li during low-grade metamorphism and fluid flux in an accretionary prism we measured the Li concentrations ([Li]) and isotopic compositions (δ7Li) of sub-greenschist and greenschist-facies Otago Schist composites, as well as cross-cutting quartz veins, which are interpreted to have precipitated from slab-derived fluids. The average [Li] of sub-greenschist facies composites (41 ± 13 μg/g, 2σ) is statistically distinct (97% confidence level, student t test) to that of greenschist facies composites (34 ± 9 μg/g, 2σ), which have experienced mass addition of silica in the form of quartz veins having [Li] between 0.4-2.3 μg/g. A linear regression of the correlation between [Li] and calculated mass additions suggests that the depletion of [Li] in greenschist facies composites is due to both dilution from the addition of the quartz veins, as well as metamorphic dehydration. The [Li] of both groups of composites correlates with their CIA (Chemical Index of Alteration) values (50-58), which are low, consistent with the inferred graywacke protolith of the Otago Schist. The δ7Li of sub-greenschist and greenschist facies composites are remarkably constant, with an average δ7Li of 0.2 ± 1.7 (2σ) and -0.5 ± 1.9 (2σ), respectively, and comparable to that of the average upper continental crust. Thus, metamorphism has had no discernable effect on δ7Li in these samples. The Li isotopic signature of the schists is similar to that seen in pelitic sedimentary rocks and likely reflects the δ7Li of the protoliths. The surprisingly light δ7Li of the quartz veins (-2.8 to -1.4) likely records kinetic fractionation associated with Li ingress into the veins from surrounding wallrock. An isotopic equilibrium fluid flow model indicates that: 1) if the [Li] of slab-derived fluids is less than a few μg/g, the δ7Li of the overlying lithologies (i.e., the schists) is not significantly influenced by the fluid flux, regardless of the δ7Li of the

  14. In situ stress magnitudes at the toe of the Nankai Trough Accretionary Prism, offshore Shikoku Island, Japan

    NASA Astrophysics Data System (ADS)

    Huffman, K. A.; Saffer, D. M.

    2016-02-01

    Quantifying the orientation and magnitude of tectonic stresses is essential toward understanding deformation and faulting in subduction zones. However, constraints on in situ horizontal stress magnitudes (Shmin and SHmax) are rare. We estimate Shmin and SHmax at Ocean Drilling Program Site 808 at the toe of the Nankai accretionary prism offshore Japan, using coupled constraints from (1) the width of wellbore breakouts together with estimates of rock strength and a model describing stress redistribution at the borehole wall and (2) limits on regional differential stress defined by failure on preexisting faults. Our analysis extends from 175 to 915 m below seafloor (mbsf) and spans the active frontal thrust. For an upper bound on rock unconfined compressive strength (UCS) and assuming hydrostatic formation pore pressure, Shmin and SHmax (referenced to the seafloor) increase from 6.5 MPa at 175 mbsf to 17.4 MPa at 915 mbsf, with the stress state gradually transitioning from a thrust or strike-slip faulting regime above 800 mbsf to a normal faulting regime below. For cases with higher formation pore pressure, horizontal stresses are slightly lower but follow a similar pattern. We show that estimated Shmin and SHmax are strongly dependent on UCS, breakout width, and friction coefficient, all of which are characterized by uncertainty. Our results suggest that the prism is near thrust failure in the upper ~300 mbsf, but far from failure below. This may be reconciled with active thrusting if thrust faults are locally weaker than the surrounding rock or if SHmax fluctuates during the seismic cycle.

  15. Causes and consequences of the great strength variability among soft Nankai accretionary prism sediments from offshore SW-Japan

    NASA Astrophysics Data System (ADS)

    Stipp, Michael; Schumann, Kai; Leiss, Bernd; Ullemeyer, Klaus

    2014-05-01

    The Nankai Trough Seismogenic Zone Experiment of the International Ocean Discovery Program (IODP) is the very first attempt to drill into the seismogenic part of a subduction zone. Offshore SW-Japan the oceanic Philippine sea plate is subducted beneath the continental Eurasian plate causing earthquakes of magnitude 8.0 to 8.5 and related tsunamis with a recurrence rate of 80-100 years. For the tsunamigenic potential of the forearc slope and accreted sediments their mechanical strength, composition and fabrics have been investigated. 19 drill core samples of IODP Expeditions 315, 316 and 333 were experimentally deformed in a triaxial cell under consolidated and undrained conditions at confining pressures of 400-1000 kPa, room temperature, axial shortening rates of 0.01-9.0 mm/min, and up to an axial strain of ˜64% (Stipp et al., 2013). With respect to the mechanical behavior, two distinct sample groups could be distinguished. Weak samples from the upper and middle forearc slope of the accretionary prism show a deviatoric peak stress after only a few percent strain (< 10%) and a continuous stress decrease after a maximum combined with a continuous increase in pore pressure. Strong samples from the accretionary prism toe display a constant residual stress at maximum level or even a continuous stress increase together with a decrease in pore pressure towards high strain (Stipp et al., 2013). Synchrotron texture and composition analysis of the experimentally deformed and undeformed samples using the Rietveld refinement program MAUD indicates an increasing strength of the illite and kaolinite textures with increasing depth down to 523 m below sea floor corresponding to a preferred mineral alignment due to compaction. Experimentally deformed samples have generally stronger textures than related undeformed core samples and they show also increasing strength of the illite and kaolinite textures with increasing axial strain. Mechanically weak samples have a bulk clay plus

  16. Geological Controls of a Gas-Hydrate System in the Frontal Taiwan Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Liao, W.; Lin, A.; Liu, C.; Hsu, S.; Lin, C.; Chen, G.; Schn Êrle, P.

    2008-12-01

    The frontal accretionary wedge offshore southwest Taiwan is characterized by rapid sedimentation, erosion along submarine canyons, and tectonic uplift due to folding and thrusting. The possible existence of gas hydrates beneath the seafloor has been indicated by geophysical and geological data. The interplays between the processes of sedimentation, erosion, and tectonic uplift therefore maintain a dynamic equilibrium system in which gas hydrates are preserved in the strata. In order to understand this system, we use data of chirp sonar, reflection seismics, and seafloor sediment samples to characterize the geological controls on the gas-hydrate system in the study area. The study area lies in the lower slope domain of the accretionary wedge. Seismic data reveals that, in the west of the study area (i.e., the frontal segment), it consists of a series of folds cored by blind thrusts; in the east of the study area (i.e., the rear segment), it consists of an array of emergent thrusts. The most frontal emergent thrust separates the frontal and rear segments of the lower slope. There are different in sedimentary features, structural styles, distributions of bottom simulating reflectors (BSRs) in the frontal and rear segments. In the frontal segment, sedimentation prevails in this region. Areas of major erosion and mass-wasting processes occur mostly in the reaches of submarine canyons. The spatial distribution of BSRs is sparse in this region and BSRs occur mostly beneath the anticlinal and bathymetric ridges. In the rear segment, it typically shows west-vergent and asymmetric fold profiles with long and planar backlimbs versus short forelimbs. The forelimbs are absent or very short in profile, and the east-dipping backlimbs are steeper beneath bathymetric ridge with its stratal dip decreasing and exhibit a homoclinal feature. There is usually a significant stratigraphic section deposited on backlimbs, showing evidences of limb rotation during fold growth. A few seafloor

  17. Landward vergent thrust faults in marine accretionary prisms off Cascadia, Sumatra, and Southern Chile: Where do they occur and what may control them?

    NASA Astrophysics Data System (ADS)

    Geersen, J.; Wilson, D. J.; Cook, B.; McNeill, L. C.; Henstock, T.; Polonia, A.; Klaeschen, D.; Gaedicke, C.; Goldfinger, C.

    2013-12-01

    Over the last decades seismic investigations have identified a number of places where landward vergent thrust faults occur in active accretionary prisms. These unusual deformation structures, that differ from the common fold-and-thrust belt model in the dip direction of the thrust sheets, have been found at the Cascadia, Sumatra and Southern Chile margins. Parameters that have been suggested to control their formation include strength, position and dip of the décollement, pore-fluid pressure, heat-flow, formation and dip direction of a backstop, strength of the wedge, and subduction of topographic features. However, the ultimate causes for their development are not adequately understood. To test the impact of the above mentioned parameters and to further shed light on the question of what drives these fault structures we investigate reflection seismic and bathymetric data from Cascadia, Sumatra, and Southern Chile. We map the detailed spatial distribution of landward vergence and investigate along and across-strike variations in fault structure, spacing, and fault initiation and development along the three margins. We further compile a synthesis of input parameters (e.g. pre-subduction deformation of the oceanic plate, convergence rate and direction, subducting plate dip, sediment thickness and composition, position of the décollement, oceanic plate roughness) for all regions that host landward vergent faults. This provides the base to identify key parameters that control the development of such fault structures on a local and potentially global scale.

  18. Seafloor distribution and last glacial to postglacial activity of mud volcanoes on the Calabrian accretionary prism, Ionian Sea

    NASA Astrophysics Data System (ADS)

    Ceramicola, Silvia; Praeg, Daniel; Cova, Andrea; Accettella, Daniela; Zecchin, Massimo

    2014-06-01

    Mud volcanoes (MVs) are abundant along the eastern Mediterranean subduction zones, recording mud breccia extrusion over long timescales (106 years), but to date relatively few have been recognised in the northern Ionian Sea on the Calabrian accretionary prism (CAP). In the present study, the seafloor distribution and recent activity of MVs is investigated across a 35,600 km2 sector of the CAP using a regional acoustic dataset (multibeam bathymetric and backscatter imagery, integrated with subbottom profiles) locally ground-truthed by sediment cores. A total of 54 MVs are identified across water depths of 150-2,750 m using up to four geophysical criteria: distinctive morphology, high backscatter, unstratified subbottom facies and, in one case, a hydroacoustic flare. Fourteen MVs are identified from 3-4 criteria, of which five have been previously proven by cores containing mud breccia beneath up to 1.6 m of hemipelagic sediments (Madonna dello Ionio MVs 1-3, Pythagoras MV and the newly named Sartori MV), while nine others are identified for the first time (Athena, Catanzaro, Cerere, Diana, Giunone, Minerva, `right foot', Venere 1 and 2). Forty other as yet unnamed MVs are inferred from 1-2 geophysical criteria (three from distinctive morphology alone). All but one possible MV lie on the inner plateau of the CAP, landwards of the Calabrian Escarpment in a zone up to 120 km wide that includes the inner pre-Messinian wedge and the fore-arc basins, where they are interpreted to record the ascent from depth of overpressured fluids that interacted with tectonic structures and with evaporitic or shale seals within the fore-arc basins. The rise of fluids may have been triggered by post-Messinian out-of-sequence tectonism that affected the entire pre-Messinian prism, but Plio-Quaternary sedimentation rates and depositional styles support the inference that significant mud volcanism has taken place only on the inner plateau. Sedimentation rates across the CAP applied to a 12

  19. Origin and transport of pore fluids in the Nankai accretionary prism inferred from chemical and isotopic compositions of pore water at cold seep sites off Kumano

    NASA Astrophysics Data System (ADS)

    Toki, Tomohiro; Higa, Ryosaku; Ijiri, Akira; Tsunogai, Urumu; Ashi, Juichiro

    2014-12-01

    We used push corers during manned submersible dives to obtain sediment samples of up to 30 cm from the subseafloor at the Oomine Ridge. The concentrations of B in pore water extracted from the sediment samples from cold seep sites were higher than could be explained by organic matter decomposition, suggesting that the seepage fluid at the site was influenced by B derived from smectite-illite alteration, which occurs between 50°C and 160°C. Although the negative δ18OH2O and δDH2O values of the pore fluids cannot be explained by freshwater derived from clay mineral dehydration (CMD), we considered the contribution of pore fluids in the shallow sediments of the accretionary prism, which showed negative δ18OH2O and δDH2O values according to the results obtained during Integrated Ocean Drilling Program (IODP) Expeditions 315 and 316. We calculated the mixing ratios based on a four-end-member mixing model including freshwater derived from CMD, pore fluids in the shallow (SPF) accretionary prism sediment, seawater (SW), and freshwater derived from methane hydrate (MH) dissociation. However, the Oomine seep fluids were unable to be explained without four end members, suggesting that deep-sourced fluids in the accretionary prism influenced the seeping fluids from this area. This finding presents the first evidence of deep-sourced fluids at cold seep sites in the Oomine Ridge, indicating that a megasplay fault is a potential pathway for the deep-sourced fluids.

  20. Difference in mechanical and hydrological properties between hemipelagic and turbidite mudstones cored from the Nankai Trough accretionary prism at Site C0002 of the IODP Expedition 315

    NASA Astrophysics Data System (ADS)

    Takahashi, M.; Azuma, S.; Uehara, S.; Inoue, A.; Kanagawa, K.

    2011-12-01

    Very low frequency earthquakes recently found in the Nankai Trough accretionary prism of SW Japan have been ascribed to rather slow faulting along out-of-sequence thrusts or splay faults (Ito and Obara, 2006a). Ito and Obara (2006b) also showed that the stress drops after these earthquakes are as small as 0.1-1% of those after regular earthquakes. Thus at least two types of earthquake faulting occur in the accretionary prism. In order to address the issue of such difference in earthquake faulting, we investigated the mechanical and hydrological properties of mudstones cored from the Nankai Trough accretionary prism. We paid attention to stress drops in particular possibly affected by such properties as permeability. Two mudstone samples designated as #51R06 and #65R02 hereafter were cored from c.a. 1000 mbsf at Site C0002 of the IODP Expedition 315. XRD analyses and SEM observations revealed that the sample #51R06 is a hemipelagic mudstone consisting of well-sorted very fine grains rich in smectite, whereas that the sample #65R02 is a turbidite mudstone consisting of poor-sorted grains rich in quartz and feldspar clasts. We have conducted triaxial compression experiments to induce brittle failure in these mudstone specimens (20 mm in diameter and 40 mm in length), after measurements of elastic and hydrological properties. At room temperature and presumed in-situ confining and pore-water pressures (36~38 MPa and 28~29 MPa, respectively), we first measured Young's modulus, Poisson's ratio, permeability and storage capacity of each specimen, then deformed it at a constant axial displacement rate of either 1 micron/sec or 10 micron/sec until its failure. Permeability measurements revealed that the sample #51R06 is 10 times less permeable (2.3×10-20 m2) than the sample #65R02 (2.9×10-19 m2). Triaxial compression experiments revealed that the maximum strength of the former (14.5 MPa) is much lower than that of the latter (20 MPa), and also that the duration time

  1. Tectonic wedging in the forearc basin - Accretionary prism transition, Lesser Antilles forearc

    NASA Technical Reports Server (NTRS)

    Torrini, Rudolph, Jr.; Speed, Robert C.

    1989-01-01

    This paper describes regional structure of the inner forearc of the southern Lesser Antilles, which contains an extensive 50-70 km wide inner forearc deformation belt (IFDB) developed above crystalline basement of the undeformed forearc basin (FAB), close to and perhaps above its probable subduction trace with Atlantic lithosphere. The IFDB is analyzed, with emphasis placed on five transects across the belt, using mainly migrated seismic sections and balanced model cross sections. The IFDB features and its evolution are discussed, with special attention given to the major structures divided by early and late stages of development, paleobathymetric history, event timing, displacement and strain, and alternative tectonic explanations.

  2. In-situ stress and strength in the Nankai inner accretionary prism at Site C0002, IODP NanTroSEIZE

    NASA Astrophysics Data System (ADS)

    Kitajima, H.; Valdez, R. D.; Kitamura, M.; Sone, H.; Saffer, D. M.; Tobin, H. J.; Hirose, T.; Kuo, S. T.

    2015-12-01

    As a part of the International Ocean Discovery Program (IODP) Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE), a deep riser borehole has been drilled into the Kumano forearc basin and the underlying inner accretionary wedge at Site C0002, located ~35 km landward from the trench. One of the primary objectives of drilling the riser site was to characterize in-situ stress and pore pressure in the hanging wall above the locked plate boundary. Here, we: (1) investigate the mechanical strength and deformation behavior of prism sediment via laboratory experiments on core samples; and (2) quantify in-situ stress (Sv, Sh, and SH), and pore pressure (Pp) in the Kumano basin and the inner prism. We conducted triaxial compression experiments on core samples recovered from ~ 2200 meters below sea floor (mbsf) during IODP Expedition 348, at effective pressures (Pe) ranging from 8 and 36 MPa, and at temperatures of either 25°C or 60°C. Our preliminary results indicate that the prism (20 - 42% porosity) rocks deform brittlely at Pe < 22 MPa, but exhibit strain hardening at Pe = 36 MPa. This pressure-porosity condition for a brittle-ductile transition is consistent with previous work defining yield models for incoming sediments at the Nankai Trough (Kitajima and Saffer, 2012). Combining P-wave velocity logs and downhole measurements of leak-off pressure at Site C0002 with an empirical relationship between P-wave velocity, porosity, and effective stress, we show that the Kumano forearc basin is in a uniaxial-strain loading path, which defines a normal faulting stress regime (Sv>SH>=Sh), whereas the inner accretionary prism is in a triaxial-strain loading path that defines a strike-slip faulting regime (SH>Sv>Sh). We estimate excess pore pressure below ~2000 mbsf ranging from 0-12 MPa, corresponding to a pore pressure ratio λ* of 0 - 0.40.

  3. Interrelationship of fluid venting and structural evolution: Alvin observations from the frontal accretionary prism, Oregon

    SciTech Connect

    Moore, J.C.; Orange, D. ); Kulm, L.D. )

    1990-06-10

    Seismic reflection and Sea Beam bathymetric data plus submarine geological measurements define a ramp anticline at the deformatoin front of the central Oregon subduction zone. At its northern termination the ramp anticline is deeply incised by a large 500-m-deep submarine canyon and cut by a probable backthrust. To the south along the strike of the fold, a smaller submarine canyon shallowly erodes the anticline, and backthrusting is not apparent in the submersible observations. Two Alvin dives along a transect through the southern canyon show active fluid vents demarked by biological communities at the frontal thrust and at the breached crest of the anticline. Along a northern transect, encompassing the large submarine canyon, 10 Alvin dives indicated no venting on the formal thrust, limited venting in the canyon, but numerous biological communities along a scarp interpreted as the surface trace of the backthrust. These observations suggest a scenario of vent and structural-geomorphic development consisting of (1) frontal thrust faulting and associated venting, facilitated by high fluid pressure; (2) erosion of the oversteepened seaward flank of the ramp anticline assisted by seepage forces and leading to fluid flow out of stratigraphically controlled conduits in the limbs of the overthrust deposits; (3) locking of the frontal thrust due to dewatering or a local decrease in wedge taper associated with development of the large canyon, leading to failure along the backthrust; and (4) redirection of fluid flow by the backthrust. Thus, within {le}0.3 m.y., deformation of the relatively permeable sediments of the Oregon margin results in stratigraphically controlled flow being partially captured by faults.

  4. Tectonic implications for the occurrence of ocean floor, hotspot, and island arc materials within accretionary prisms: Examples from the Mesozoic-Cenozoic NW Pacific Rim

    NASA Astrophysics Data System (ADS)

    Ogawa, Y.; Hirano, N.; Hirano, N.; Taniguchi, H.; Taniguchi, H.; Taniguchi, H.

    2001-12-01

    On-land Mesozoic-Cenozoic accretionary prisms exposed in Japan commonly have basaltic rocks incorporated as blocks into melanges or fault zones during a prolonged history of subduction and/or obduction. Chemical signatures of these basaltic rocks and their mode of occurrence with sedimentary covers and/or associated sedimentary rocks indicate that most of these isolated small basaltic blocks consistently display a WPB chemistry, whereas large slabs of basaltic rocks around the Izu Arc collision zone show MORB chemistry with rare examples of IAT, BABB, and/or WPB affinities. Comparing with the present uniformitarian examples of convergent plate boundaries in the western Pacific that we know through the DSDP and ODP projects and submersible and seismic surveys, we can interpret some of the basaltic material with WPB affinity in the Japanese accretionary prisms as relict edifices of seamounts with hotspot origin. These hotspot-related basaltic rocks are commonly associated with reefal limestones and were incorporated into continental margin melanges either by submarine sliding from the downgoing oceanic plate or by shallow-level offscraping along decollement surfaces during the subduction of oceanic plates. Older, uplifted parts of the fossil accretionary prisms on the continent side further inward from the trench where the deeper levels of accreted material are exposed include larger amounts of basaltic blocks. This observation suggests that significant amount of underplating might have occurred in the deeper levels of oceanic crust along decollement zones at structurally lower depths. The metamorphic belts (e.g.Sambagawa, Chichibu, Shimanto etc.) have commonly alkaline rocks or plateau-type E-MORB basalts without any trace of N-MORB rocks with rare special exceptions. Besides these ordinary accretionary prism examples formed by a simple plate subduction system, another type of accretion resulting from island arc or ridge collision is observed to have occurred in

  5. Partition between collision and subduction accretionary prisms along an inherited transcurrent fault zone: New insights on the Taiwan fold and thrust belt

    NASA Astrophysics Data System (ADS)

    Brusset, StéPhane; Souquet, Pierre; DéRamond, Joachim; Sibuet, Jean-Claude; Hsu, Shu-Kun; Deffontaines, Benoã®T.; Chu, Hao-Tsu

    1999-06-01

    A new geotectonic framework of the Taiwan orogen is presented in accordance with the hypothesis of an oblique arc-arc collision. The colliding Luzon arc is physically connected to the eastern Coastal Range in which a subduction complex remnant is preserved and backthrust with intra-arc sediments in a small retroforeland basin. A southern and extinct extension of the Ryukyu arc is characterized in western Taiwan. It displays a duplex structure (Tananao and Backbone horses and Lishan triangle zone) between a buried floor thrust located in the arc crust and a roof thrust developed in the arc cover (Hsüehshan Range and South Backbone Range). Westward the basal thrust climbs in the sedimentary series of the western proforeland (Foothills and Hengchun Peninsula) and dies out hi a buried tip line. The northern part of the orogen, including all the Tananao arc core, is shown as an intra-oceanic-continental arc-arc collision belt characterized by an unroofed duplex culmination above a leading floor thrust and both proforeland and retroforeland basins. The southern part, which displays a roof thrust sequence above a buried duplex, is shown as an accretionary prism built in a transition zone between continent and oceanic subduction (transition from the Asian continental crust, including the former Ryukyu arc, to the oceanic Old Philippine Sea crust). The partition is believed to be induced by a deep intracontinental transcurrent fault zone able to influence the difference in shortening, duplex pattern, and leading thrust depth. The evolution was controlled by the Ryukyu subduction (backarc extension, arc magmatism extinction, and cooling and intra-arc collapse) until the early middle Miocene (around 15 Ma) and then it was controlled by the Luzon arc progression (continental subduction, collision, indentation, and hinterland uplift and frontal thrust propagation).

  6. Characterizing the Inner Accretionary Prism of the Nankai Trough with 3D Seismic and Logging While Drilling at IODP Site C0002

    NASA Astrophysics Data System (ADS)

    Boston, B.; Moore, G. F.; Jurado, M. J.; Sone, H.; Tobin, H. J.; Saffer, D. M.; Hirose, T.; Toczko, S.; Maeda, L.

    2014-12-01

    The deeper, inner parts of active accretionary prisms have been poorly studied due the lack of drilling data, low seismic image quality and typically thick overlying sediments. Our project focuses on the interior of the Nankai Trough inner accretionary prism using deep scientific drilling and a 3D seismic cube. International Ocean Discovery Program (IODP) Expedition 348 extended the existing riser hole to more than 3000 meters below seafloor (mbsf) at Site C0002. Logging while drilling (LWD) data included gamma ray, resistivity, resistivity image, and sonic logs. LWD analysis of the lower section revealed on the borehole images intense deformation characterized by steep bedding, faults and fractures. Bedding plane orientations were measured throughout, with minor gaps at heavily deformed zones disrupting the quality of the resistivity images. Bedding trends are predominantly steeply dipping (60-90°) to the NW. Interpretation of fractures and faults in the image log revealed the existence of different sets of fractures and faults and variable fracture density, remarkably high at fault zones. Gamma ray, resistivity and sonic logs indicated generally homogenous lithology interpretation along this section, consistent with the "silty-claystone" predominant lithologies described on cutting samples. Drops in sonic velocity were observed at the fault zones defined on borehole images. Seismic reflection interpretation of the deep faults in the inner prism is exceedingly difficult due to a strong seafloor multiple, high-angle bedding dips, and low frequency of the data. Structural reconstructions were employed to test whether folding of seismic horizons in the overlying forearc basin could be from an interpreted paleothrust within the inner prism. We used a trishear-based restoration to estimate fault slip on folded horizons landward of C0002. We estimate ~500 m of slip from a steeply dipping deep thrust within the last ~0.9 Ma. Folding is not found in the Kumano sediments

  7. Evaluation of Coseismic Fluid-Rock Interaction in Fault Zones on the Basis of Geochemistry of Fault Rocks in Accretionary Prisms

    NASA Astrophysics Data System (ADS)

    Ishikawa, T.; Hirono, T.; Honda, G.

    2011-12-01

    Recent studies revealed that concentration and isotopic composition of fluid-mobile trace elements such as Li, Rb, Cs and Sr in slip-zone rocks can change significantly during coseismic fluid-rock interaction at high temperatures (e.g., Ishikawa et al., 2008). In this study, we summarize the results obtained for fault-zone rocks recovered from various depths of the subduction zones. Analysis of a slip-zone sample recovered from shallow portion (0.27 km bsf) of the magasplay fault at Site C0004, IODP Exp. 316, Nankai Trough showed no clear fluid-induced geochemical signals, although a peak temperature over 300 deg. C is estimated on the basis of vitrinite reflectance data (Sakaguchi et al., 2011). In contrast, a major reverse fault in a fossil accretionary prism, the Emi Group (burial depth, 1-2 km) exhibited marked decreases of Li, Rb and Cs relative to adjacent host rocks, suggesting coseismic fluid-rock interactions at >350 deg. C. Geochemical signals observed in the Emi slip zone have a strong resemblance to those observed in the Taiwan chelungpu fault at comparable depths (1.1-1.2 km). Slip-zone samples collected from a fossil out-of-sequence thrust at greater depth (2.5-5.5 km) adjacent to the Kure Melange in the Shimanto accretionary prism showed unique geochemical characteristics, in which effects from disequilibrium flash melting to generate pseudotachylyte coexist with those from fluid-rock interactions at >350 deg. C. In the cases of Emi and Chelungpu, it is possible that the fluid-induced geochemical signatures, together with fluidization structures observed in these samples, resulted from thermal pressurization. On the other hand, the Kure data suggest a slip process in which high-temperature pore fluids were generated by frictional slip, but the thermally-enhanced pressure might not have reached a sufficient level to cause thermal pressurization, and the temperature continued to increase to attain melting. Kinetic estimation suggests that fluid

  8. The relationship between mud volcanoes, petroleum migration and accretionary prisms: Lessons from the Caucasus, the Australian margin and Venezuela

    SciTech Connect

    Ware, P.

    1996-08-01

    Mud volcanoes have been widely documented in areas of overpressure where explosive expansion of trapped methane has occurred during argillokinesis. In an area with high sedimentation rate, such as the Gulf of Mexico, there may be no time for fine-grained sediment to de-water before being covered by impermeable material. In an accretionary wedge this process is complicated by overthrusting of off-scraped material which increases the overburden pressure and provides many more avenues for the migration of fluids through the system. In some cases, such as is seen in the Caribbean, the fluids may escape directly to the surface (or seabottom) through high permeability beds. When this happens there may be no diapirism. In other cases, such as in Venezuela, the forearc may be the site of rapid, laterally-derived, sedimentation, and fluids from the overthrusted rocks may be forced to escape through several kilometers of recent deltaic sediments. Since these fluids may include petroleum, this has obvious exploration potential. If there are no suitable reservoir rocks, such as in Timor, there may be no commercial accumulations. However, many giant fields are associated, world-wide, with mud volcanoes, such as those in Azerbaijan.

  9. Influence of Stress History on Elastic and Frictional Properties of Core Material from IODP Expeditions 315 and 316, NanTroSEIZE Transect: Implications for the Nankai Trough Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Knuth, M. W.; Tobin, H. J.; Marone, C.; Saffer, D. M.; Hashimoto, Y.

    2009-12-01

    We present results of ultrasonic P and S-wave velocity measurements on core material recovered during NanTroSEIZE Stage 1 Expeditions 315 and 316 to the Nankai Trough Accretionary Margin, focusing on how different stress paths during subduction and exhumation along regional thrust faults influence the elastic moduli and anisotropy of various components of the accretionary prism. The influence of changes in pore pressure and confining pressure on the elastic properties of prism material has important implications for its mechanical strength, and understanding how elastic properties change along various stress paths will help us use 3D seismic tomography to draw inferences about overpressurization and fluid flow within the accretionary prism. We compare the velocities measured during shipboard physical properties characterization and logging-while-drilling data from Expedition 314 with 3D seismic velocity data and the results of previous shore-based studies to establish in situ conditions for material at various locations within the prism. We test both intact core material and disaggregated gouge and unlithified sediments from the upper prism, subjecting both samples types to a progression of confining pressure, pore pressure, and axial loading conditions representing normal consolidation and overconsolidation stress paths due to compaction and dewatering during burial and subsequent uplift by thrust faulting. While making continuous ultrasonic velocity measurements to determine changes in dynamic and quasistatic elastic moduli during axial and isotropic loading, we also subject granular material to frictional shear in a biaxial double-direct shearing configuration to measure how its frictional properties vary as a function of stress history.

  10. The Imbert Formation of northern Hispaniola: a tectono-sedimentary record of arc-continent collision and ophiolite emplacement in the northern Caribbean subduction-accretionary prism

    NASA Astrophysics Data System (ADS)

    Escuder-Viruete, J.; Suárez-Rodríguez, A.; Gabites, J.; Pérez-Estaún, A.

    2015-06-01

    In northern Hispaniola, the Imbert Formation (Fm) has been interpreted as an orogenic "mélange" originally deposited as trench-fill sediments, an accretionary (subduction) complex formed above a SW-dipping subduction zone, or the sedimentary result of the early oblique collision of the Caribbean plate with the Bahama Platform in the middle Eocene. However, new stratigraphical, structural, geochemical and geochronological data from northern Hispaniola indicate that the Imbert Fm constitutes a coarsening-upward stratigraphic sequence that records the transition of the sedimentation from a pre-collisional forearc to a syn-collisional piggy-back basin. This piggy-back basin was transported on top of the Puerto Plata ophiolitic complex slab and structurally underlying accreted units of the Rio San Juan complex, as it was emplaced onto the North America continental margin units. The Imbert Fm unconformably overlies different structural levels of the Caribbean subduction-accretionary prism, including a supra-subduction zone ophiolite, and consists of three laterally discontinuous units that record the exhumation of the underlying basement. The distal turbiditic lower unit includes the latest volcanic activity of the Caribbean island arc; the more proximal turbiditic intermediate unit is moderately affected by syn-sedimentary faulting; and the upper unit is a (caotic) olistostromic unit, composed of serpentinite-rich polymictic breccias, conglomerates and sandstones, strongly deformed by syn-sedimentary faulting, slumping and sliding processes. The Imbert Fm is followed by subsidence and turbiditic deposition of the overlying El Mamey Group. The 40Ar / 39Ar plagioclase plateau ages obtained in gabbroic rocks from the Puerto Plata ophiolitic complex indicate its exhumation at ∼ 45-40 Ma (lower-to-middle Eocene), contemporaneously to the sedimentation of the overlying Imbert Fm. These cooling ages imply the uplift to the surface and submarine erosion of the complex to

  11. The Imbert Formation of northern Hispaniola: a tectono-sedimentary record of arc-continent collision and ophiolite emplacement in the northern Caribbean subduction-accretionary prism

    NASA Astrophysics Data System (ADS)

    Escuder-Viruete, J.; Suárez-Rodríguez, Á.; Gabites, J.; Pérez-Estaún, A.

    2016-01-01

    In northern Hispaniola, the Imbert Formation (Fm) has been interpreted as an orogenic "mélange" originally deposited as trench-fill sediments, an accretionary (subduction) complex formed above a SW-dipping subduction zone, or the sedimentary result of the early oblique collision of the Caribbean plate with the Bahama Platform in the middle Eocene. However, new stratigraphical, structural, geochemical and geochronological data from northern Hispaniola indicate that the Imbert Fm constitutes a coarsening-upward stratigraphic sequence that records the transition of the sedimentation from a pre-collisional forearc to a syn-collisional basin. This basin was transported on top of the Puerto Plata ophiolitic complex slab and structurally underlying accreted units of the Rio San Juan complex, as it was emplaced onto the North America continental margin units.

    The Imbert Fm unconformably overlies different structural levels of the Caribbean subduction-accretionary prism, including a supra-subduction zone ophiolite, and consists of three laterally discontinuous units that record the exhumation of the underlying basement. The distal turbiditic lower unit includes the latest volcanic activity of the Caribbean island arc; the more proximal turbiditic intermediate unit is moderately affected by syn-sedimentary faulting; and the upper unit is a (chaotic) olistostromic unit, composed of serpentinite-rich polymictic breccias, conglomerates and sandstones, strongly deformed by syn-sedimentary faulting, slumping and sliding processes. The Imbert Fm is followed by subsidence and turbiditic deposition of the overlying El Mamey Group.

    The 40Ar / 39Ar plagioclase plateau ages obtained in gabbroic rocks from the Puerto Plata ophiolitic complex indicate its exhumation at ˜ 45-40 Ma (lower-to-middle Eocene), contemporaneously to the sedimentation of the overlying Imbert Fm. These cooling ages imply the uplift to the surface and submarine erosion of the complex to

  12. PRogram In Support of Moms (PRISM): Development and Beta Testing.

    PubMed

    Byatt, Nancy; Pbert, Lori; Hosein, Safiyah; Swartz, Holly A; Weinreb, Linda; Allison, Jeroan; Ziedonis, Douglas

    2016-08-01

    Most women with perinatal depression do not receive depression treatment. The authors describe the development and beta testing of a new program, PRogram In Support of Moms (PRISM), to improve treatment of perinatal depression in obstetric practices. A multidisciplinary work group of seven perinatal and behavioral health professionals was convened to design, refine, and beta-test PRISM in an obstetric practice. Iterative feedback and problem solving facilitated development of PRISM components, which include provider training and a toolkit, screening procedures, implementation assistance, and access to immediate psychiatric consultation. Beta testing with 50 patients over two months demonstrated feasibility and suggested that PRISM may improve provider screening rates and self-efficacy to address depression. On the basis of lessons learned, PRISM will be enhanced to integrate proactive patient engagement and monitoring into obstetric practices. PRISM may help overcome patient-, provider-, and system-level barriers to managing perinatal depression in obstetric settings. PMID:27079994

  13. Characterization of structures of the Nankai Trough accretionary prism from integrated analyses of LWD log response, resistivity images and clay mineralogy of cuttings: Expedition 338 Site C0002

    NASA Astrophysics Data System (ADS)

    Jurado, Maria Jose; Schleicher, Anja

    2014-05-01

    The objective of our research is a detailed characterization of structures on the basis of LWD oriented images and logs,and clay mineralogy of cuttings from Hole C0002F of the Nankai Trough accretionary prism. Our results show an integrated interpretation of structures derived from borehole images, petrophysical characterization on LWD logs and cuttings mineralogy. The geometry of the structure intersected at Hole C0002F has been characterized by the interpretation of oriented borehole resistivity images acquired during IODP Expedition 338. The characterization of structural features, faults and fracture zones is based on a detailed post-cruise interpretation of bedding and fractures on borehole images and also on the analysis of Logging While Drilling (LWD) log response (gamma radioactivity, resistivity and sonic logs). The interpretation and complete characterization of structures (fractures, fracture zones, fault zones, folds) was achieved after detailed shorebased reprocessing of resistivity images, which allowed to enhance bedding and fracture's imaging for geometry and orientation interpretation. In order to characterize distinctive petrophysical properties based on LWD log response, it could be compared with compositional changes derived from cuttings analyses. Cuttings analyses were used to calibrate and to characterize log response and to verify interpretations in terms of changes in composition and texture at fractures and fault zones defined on borehole images. Cuttings were taken routinely every 5 m during Expedition 338, indicating a clay-dominated lithology of silty claystone with interbeds of weakly consolidated, fine sandstones. The main mineralogical components are clay minerals, quartz, feldspar and calcite. Selected cuttings were taken from areas of interest as defined on LWD logs and images. The clay mineralogy was investigated on the <2 micron clay-size fraction, with special focus on smectite and illite minerals. Based on X-ray diffraction

  14. Development of rotating prism mechanism and athermalized prism mounting for space

    NASA Astrophysics Data System (ADS)

    Beebe, Chip R.; Brooks, Mark J.; Davis, Michael W.; Klar, Robert A.; Roberts, John M.; Roming, Peter W. A.; Rose, Randall J.; Winters, Gregory S.

    2013-09-01

    Space and launch environments demand robust, low mass, and thermally insensitive mechanisms and optical mount designs. The rotating prism mechanism (RPM), a component of the stabilized dispersive focal plane system (SDFPS), is a spectral disperser mechanism that enables the SDFPS to deliver spectroscopic or direct imaging functionality using only a single optical path. The RPM is a redundant, vacuum-compatible, self-indexing, motorized mechanism that provides robust, athermalized prism mounting for two sets of matching prisms. Each set is composed of a BK7 and a CaF2 prism, both 70 mm in diameter. With the prism sets separated by 1 mm, the RPM rotates the two sets relative to one another over a 180° range, and maintains their alignment over a wide temperature range (190-308K). The RPM design incorporates self-indexing and backlash prevention features as well as redundant motors, bearings, and drive trains. The RPM was functionally tested in a thermal vacuum chamber at 210K and <1.0x10-6 mbar, and employed in the top-level SDFPS system testing. This paper presents the mechanical design, analysis, alignment measurements, and test results from the prototype RPM development effort.

  15. Ultrasonic P-wave velocity measurements with variable effective pressure at the boundary between slope basin sediments and the accretionary prism: IODP Expedition 315 Site C0001

    NASA Astrophysics Data System (ADS)

    Hashimoto, Y.; Knuth, M. W.; Tobin, H. J.; 314/315/316 Scientist, I.

    2008-12-01

    IODP Expedition 315 Site C0001 is located on the hanging wall of the midslope megasplay fault in the Nankai subduction zone off Kii peninsula (SW Japan), and penetrated an unconformity between ~200 m thick slope basin sediments and the accretionary prism. While a down-section porosity increase was clearly observed at the boundary from ~50% to ~60%, logging velocity does not appear to decrease at the boundary, which suggests that different diagenetic processes might exist above and below the boundary. In this study, we conducted ultrasonic P-wave velocity measurements with pore pressure control. We also conducted observations of sediment and chemical analysis. We examined the relationships between the acoustic properties, sediment textures, logging data from IODP Expedition 314 Site C0001 and data from shipboard core analysis. The ultrasonic P-wave velocity measurements were conducted under constant pore pressure (500 kPa) and varying confining pressure to control effective pressure. The confining pressure ranges from 550 kPa to a maximum calculated from the density of overlying sediments (lithostatic pressure - hydrostatic pressure). 8 samples were analyzed, located from ~70 m to ~450 m below the sea floor. P-wave velocity ranges from ~1620 m/s to ~1990 m/s under the hydrostatic pressure condition. These velocities are in good agreement with the logging data. Porosity-velocity relationship in the analyzed data also coincide with that observed in the logging data. Samples shallower than ~300 m fall within previously-defined empirical relationships for normal- and high- consolidation. The deeper samples (at ~370 m and ~450 m below sea floor) show much higher velocity than that predicted by the empirical relationship, suggesting that significant cementation is present in those samples. The textural observations of sediments indicate a decrease in pore space with depth. Quartz and feldspar grains are surrounded by clay mineral matrices. Grain size seems to be almost

  16. Structural development of the western Makran Accretionary Complex, Offshore Iran

    NASA Astrophysics Data System (ADS)

    Burberry, C. M.; Jackson, C. A.

    2013-12-01

    The Makran Accretionary Complex (MAC), which straddles the southern offshore regions of Iran and Pakistan, is a fold-thrust system bound by the Murray Ridge and Ornach Nal Fault to the east, and the Minab Fault System (MFS) to the west. It is c. 1000 km wide and the frontal c. 125 km of the system is submerged beneath the Gulf of Oman. Relatively little is known about this system, despite the fact that constitutes a large portion of the Central Tethyan Orogen and is one of the largest accretionary complexes in the world. We use offshore 2D seismic reflection data to investigate the structural style and evolution of the Iranian segment of the MAC. The MAC is divided into two morphologically distinct domains: (i) a northern domain (Domain 1), which is located landward of a prominant break-in-slope on the seabed and is characterised by a series of normal fault-bound sub-basins that are approximately 50 km wide, and which contain numerous, unconformity-bound seismic units; and (ii) a southern domain (Domain 2), which is located basinward of the prominent seabed slope break, and is characterised by alternating ridges and troughs. Seismic data indicate that these structures are laterally continuous (over 100 km long) north-dipping thrust faults, which are overlain by south-verging, non-cylindrical, fault-propagation folds. Towards the western end of the study area, immediately offshore of the prominent onshore trace of the MFS, there is no single structure that can be reliably interpreted as the offshore extension of the MFS. Instead, a series of oblique-slip faults with thrust and strike-slip components are identified, spanning a zone that is c. 40 km wide. In the north and close to the coastline, the faults are dominantly strike-slip, whereas further south, closer to the deformation front, the thrust-sense component is more important. Irrespective of their slip sense, faults in this zone have a similar N-S strike to the onshore trace of the MFS. In addition, the basin

  17. Preliminary results of three-dimensional stress orientation in the accretionary prism in Nankai Subduction Zone, Japan by anelastic strain recovery measurements of core samples retrieved from IODP NanTroSEIZE Site C0009

    NASA Astrophysics Data System (ADS)

    Lin, W.; Byrne, T. B.; Yamamoto, Y.

    2010-12-01

    During IODP Expedition 319, the first riser-drilling borehole in ocean was penetrated by D/V CHIKYU at Site C0009 in the Nankai convergent margin, Japan. From 0 mbsf (meters below seafloor) to 1285 mbsf, the borehole crossed the Kumano forearc basin and from 1285 mbsf to the bottom depth of 1604 mbsf, the Nankai accretionary prism. In a short depth range of 84.20 m from 1509.7 to 1593.9 mbsf, core samples were retrieved by rotary core barrel drilling. We collected 3 whole-round core samples for measurements of anelastic strain recovery (ASR) by the same methods of sample preparation and anelastic strain data acquisition conducted in the previous Stage-1 expeditions of the same NanTroSEIZE drilling program (Byrne et al., 2009; GRL, Vol.36, L23310). Anelastic normal strains, measured every ten minutes in nine directions, including six independent directions, were used to calculate the anelastic strain tensors. All three samples showed coherent strain recovery over a long period more than 1 month. The three samples were from C0009A (3R,1531 mbsf; 4R, 1540 mbsf and 8R, 1577 mbsf, respectively) in lithologic Unit IV interpreted as accretionary prism or deformed slope sediments. All samples are composed of silty clays or hemipelagic muds with relatively high porosities (30%~). The ASR measurement results in Kumano Forearc Basin obtained from C0002 (Byrne et al., 2009) showed the maximum stress orientation is nearly vertical and a normal stress regime. However, the ASR results in the accretionary prism from C0009 show that the maximum principal stress axes plunge gently or are nearly horizontal and the stress regimes appear to be strike-slip or thrust (reverse fault) types. The maximum horizontal principal stress orientaions obtained from the ASR tests also show very good consistency with the stress orientaions determined from borehole breakouts in the same borehole and the same depth range (Lin et al., 2010; GRL, Vol.37, L13303). These results suggest that three

  18. The Pacific Oaks College's Prism Principles Professional Development Approach

    ERIC Educational Resources Information Center

    Beyer, Kalani

    2012-01-01

    In a struggling atmosphere for education, one college is optimistic about the future by offering school districts its PRISM Principles professional development as a means to ensure that "no child is left behind." Pacific Oaks College & Children's School is known for its premiere programs in early childhood education, human…

  19. Confined deep water system development on the accretionary wedge (Miocene, Kahramanmaraş Foreland Basin, S turkey)

    NASA Astrophysics Data System (ADS)

    Gül, Murat; Cronin, Bryan T.; Gürbüz, Kemal

    2012-09-01

    According to theoretical studies, the foreland basin consists of: accretionary wedge (including wedge top or piggyback basin), foredeep, forebulge and backbulge depozones. All of them are parallel to the orogenic belts of the overlying and underlying plates. The closure of the southern branch of the Neotethys during the Late Cretaceous led to an oblique collision of the Arabian Plate and the Anatolide-Taurides Platform, leading to the development of the Miocene Kahramanmaraş Foreland Basin (KFB). Thus, the promontory shape of the Arabian Plate prevented the development of an accretionary wedge parallel to the orogenic belt. The accretionary wedge of the KFB includes blocks of various sizes and age (mainly Mesozoic limestone) scattered within an Early Tertiary matrix (mass wasting deposits and shallow to deep marine sediments). At the beginning of the Miocene, transtensional tectonism led to the development of half-graben basins on top of the accretionary wedge. These basins (namely; the Tekir and Çukurhisar) also cut the foredeep of the KFB obliquely (in contrast with the theoretical study). This paper focuses on the evolution and fillings of those basins. Initially, claystone and basin margin reef deposits filled the half-graben basins as a consequence of the Lower Miocene sea invasion. Then, long and narrow conglomeratic channels starting from the northern edge of the basins (fan-delta) progressed southwards, passing into sandy lobes, then into claystones. An activation of the boundary faults of the wedge top basin stopped the progression of the Lower-Middle Miocene sediments and led to their deformation. Then, the sedimentation of the KFB shifted towards the basin centre during the Middle Miocene.

  20. DEVELOPMENT OF A NEW OREGON PRECIPITATION MAP USING THE PRISM MODEL

    EPA Science Inventory

    Significant progress in our ability to distribute point monthly and annual precipitation data to a regular grid in complex terrain has recently been achieved through the development of PRISM (Precipitation-elevation Regressions on Independent Slopes Model) . PRISM is well suited ...

  1. Development of an unbonded capping system for clay masonry prisms

    SciTech Connect

    Crouch, L.K.; Henderson, R.C.; Sneed, W.A. Jr.

    1999-07-01

    To ascertain if an unbonded capping system was feasible for clay masonry prisms, the compressive strengths of thirty clay masonry prisms capped with an unbonded capping system modeled after ASTM C 1231 were compared with those of thirty masonry prisms capped with ASTM C 67 approved high-strength gypsum cement at the ages of 7 and 28 days. All prisms were constructed by a professional mason using Grade SW, Type FBS cored face brick from the same lot and ASTM C 270 Type S PC-lime mortar. There was no significant difference in mean compressive strength for the two capping methods at either age. In addition, capping with the unbonded capping system was faster and easier. Further, 28-day results obtained using the unbonded capping system had a lower coefficient of variation and higher mean compressive strength than those obtained with high-strength gypsum.

  2. Fluid venting and seepage at accretionary ridges: the Four Way Closure Ridge offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Klaucke, Ingo; Berndt, Christian; Crutchley, Gareth; Chi, Wu-Cheng; Lin, Saulwood; Muff, Sina

    2015-12-01

    Within the accretionary prism offshore SW Taiwan, widespread gas hydrate accumulations are postulated to occur based on the presence of a bottom simulating reflection. Methane seepage, however, is also widespread at accretionary ridges offshore SW Taiwan and may indicate a significant loss of methane bypassing the gas hydrate system. Four Way Closure Ridge, located in 1,500 m water depth, is an anticlinal ridge that would constitute an ideal trap for methane and consequently represents a site with good potential for gas hydrate accumulations. The analysis of high-resolution bathymetry, deep-towed sidescan sonar imagery, high-resolution seismic profiling and towed video observations of the seafloor shows that Four Way Closure Ridge is and has been a site of intensive methane seepage. Continuous seepage is mainly evidenced by large accumulations of authigenic carbonate precipitates, which appear to be controlled by the creation of fluid pathways through faulting. Consequently, Four Way Closure Ridge is not a closed system in terms of fluid migration and seepage. A conceptual model of the evolution of gas hydrates and seepage at accretionary ridges suggests that seepage is common and may be a standard feature during the geological development of ridges in accretionary prisms. The observation of seafloor seepage alone is therefore not a reliable indicator of exploitable gas hydrate accumulations at depth.

  3. Fluid venting and seepage at accretionary ridges: the Four Way Closure Ridge offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Klaucke, Ingo; Berndt, Christian; Crutchley, Gareth; Chi, Wu-Cheng; Lin, Saulwood; Muff, Sina

    2016-06-01

    Within the accretionary prism offshore SW Taiwan, widespread gas hydrate accumulations are postulated to occur based on the presence of a bottom simulating reflection. Methane seepage, however, is also widespread at accretionary ridges offshore SW Taiwan and may indicate a significant loss of methane bypassing the gas hydrate system. Four Way Closure Ridge, located in 1,500 m water depth, is an anticlinal ridge that would constitute an ideal trap for methane and consequently represents a site with good potential for gas hydrate accumulations. The analysis of high-resolution bathymetry, deep-towed sidescan sonar imagery, high-resolution seismic profiling and towed video observations of the seafloor shows that Four Way Closure Ridge is and has been a site of intensive methane seepage. Continuous seepage is mainly evidenced by large accumulations of authigenic carbonate precipitates, which appear to be controlled by the creation of fluid pathways through faulting. Consequently, Four Way Closure Ridge is not a closed system in terms of fluid migration and seepage. A conceptual model of the evolution of gas hydrates and seepage at accretionary ridges suggests that seepage is common and may be a standard feature during the geological development of ridges in accretionary prisms. The observation of seafloor seepage alone is therefore not a reliable indicator of exploitable gas hydrate accumulations at depth.

  4. A stochastic prediction of in situ stress magnitudes from the distributions of rock strength and breakout width at IODP Hole C0002A in Nankai accretionary prism, SW Japan

    NASA Astrophysics Data System (ADS)

    Song, Insun; Chang, Chandong; Lee, Hikweon

    2015-04-01

    . The results from this new approach of stress estimation are comparable with previous other results (e.g., Chang et al., 2010, G3; Lee et al., 2013, MPG). This stochastic model is prominent because it gives not only both values of SHmax and Shmin simultaneously but also information about statistical reliability of the determined values quantified by sensitivity and uncertainty. Our result shows that the two stress magnitudes in Nankai accretionary prism are not completely independent in terms of sensitivity, suggesting that other independent measure of one of the two stresses might be definitely useful (e.g., from leak-off test).

  5. Interaction between hydrocarbon seepage, chemosynthetic communities and bottom water redox at cold seeps of the Makran accretionary prism: insights from habitat-specific pore water sampling and modeling

    NASA Astrophysics Data System (ADS)

    Fischer, D.; Sahling, H.; Nöthen, K.; Bohrmann, G.; Zabel, M.; Kasten, S.

    2011-09-01

    upward sulfide flux via AOM. Due to the introduction of oxygenated bottom water into the sediment via bioirrigation the depth of the sulfide sink gradually deepens towards outer habitats. We therefore suggest that - in addition to the oxygen levels in the water column which determine whether macrofaunal communities can develop or not - it is rather the depth of the SMTZ and thus of sulfide production that determines which chemosynthetic communities are able to exploit the sulfide at depth. Moreover, large vesicomyid clams most efficiently expand the sulfate zone in the sediment and cut off smaller or immobile organisms from the sulfide source.

  6. Interaction between hydrocarbon seepage, chemosynthetic communities, and bottom water redox at cold seeps of the Makran accretionary prism: insights from habitat-specific pore water sampling and modeling

    NASA Astrophysics Data System (ADS)

    Fischer, D.; Sahling, H.; Nöthen, K.; Bohrmann, G.; Zabel, M.; Kasten, S.

    2012-06-01

    environment and fuel upward sulfide flux via AOM. Furthermore, due to the introduction of oxygenated bottom water into the sediment via bioirrigation, the depth of the sulfide sink gradually deepens towards outer habitats. We therefore suggest that - in addition to the oxygen levels in the water column, which determine whether macrofaunal communities can develop or not - it is the depth of the SMT and thus of sulfide production that determines which chemosynthetic communities are able to exploit the sulfide at depth. We hypothesize that large vesicomyid clams, by efficiently expanding the sulfate zone down into the sediment, could cut off smaller or less mobile organisms, as e.g. small clams and sulfur bacteria, from the sulfide source.

  7. Development of tectono-sedimentary mélanges in accretionary wedges: Insights from analog modeling

    NASA Astrophysics Data System (ADS)

    Genti, M.; Malavieille, J.; Molli, G.; Dominguez, S.; Taboada, A.; Vitale-Brovarone, A.

    2012-04-01

    Orogenic wedges locally present chaotic tectonostratigraphic units that contain exotic blocks of various size, origin, age and lithology, embedded in a sedimentary matrix. The occurrence of ophiolitic blocks, sometimes huge, in such "mélanges" raises questions on i) the mechanisms responsible for the incorporation of oceanic basement rocks into an accretionary wedge and ii) the mechanisms allowing exhumation and possibly redeposition of these exotic elements in "mélanges" during wedge growth. The tectonic evolution of the back part of doubly vergent accretionary wedges is mainly controled by backthrusting. The retrowedge is characterized by steep slopes that are prone to gravitational instabilities. We assume that these steep slopes trigger submarine landslides playing a major erosional role and therefore inducing huge mass transfers. This erosion allows exhumation of the ophiolitic fragments formerly accreted at the base of the wedge and then reworked as tectono-sedimentary "mélanges" redeposited in proximal basins located at the base of the retrowedge slope. These basin deposits are then continuously involved in backthrusting-induced deformation. In this study, we present the results of a series of analog experiments performed to characterize the processes and parameters responsible for accretion, exhumation and final tectonosedimentary reworking of oceanic basement lithosphere fragments in an accretionary wedge. The experimental setup is designed to simulate the interaction between tectonics, erosion and sedimentation. Different configurations are applied to study the impact of various parameters, such as irregular oceanic floor due to structural inheritance, or the presence of layers with contrasted rheology that can affect deformation partitioning in the wedge (frontal accretion vs basal accretion) influencing its growth. The experimental results are then compared with observations on ophiolite-bearing mélanges in the Taïwan (Lichi mélange) and northern

  8. Development and application of GIS-based PRISM integration through a plugin approach

    NASA Astrophysics Data System (ADS)

    Lee, Woo-Seop; Chun, Jong Ahn; Kang, Kwangmin

    2014-05-01

    A PRISM (Parameter-elevation Regressions on Independent Slopes Model) QGIS-plugin was developed on Quantum GIS platform in this study. This Quantum GIS plugin system provides user-friendly graphic user interfaces (GUIs) so that users can obtain gridded meteorological data of high resolutions (1 km × 1 km). Also, this software is designed to run on a personal computer so that it does not require an internet access or a sophisticated computer system. This module is a user-friendly system that a user can generate PRISM data with ease. The proposed PRISM QGIS-plugin is a hybrid statistical-geographic model system that uses coarse resolution datasets (APHRODITE datasets in this study) with digital elevation data to generate the fine-resolution gridded precipitation. To validate the performance of the software, Prek Thnot River Basin in Kandal, Cambodia is selected for application. Overall statistical analysis shows promising outputs generated by the proposed plugin. Error measures such as RMSE (Root Mean Square Error) and MAPE (Mean Absolute Percentage Error) were used to evaluate the performance of the developed PRISM QGIS-plugin. Evaluation results using RMSE and MAPE were 2.76 mm and 4.2%, respectively. This study suggested that the plugin can be used to generate high resolution precipitation datasets for hydrological and climatological studies at a watershed where observed weather datasets are limited.

  9. Development and Validation of PRISM: A Survey Tool to Identify Diabetes Self-Management Barriers

    PubMed Central

    Cox, Elizabeth D.; Fritz, Katie A.; Hansen, Kristofer W.; Brown, Roger L.; Rajamanickam, Victoria; Wiles, Kaelyn E.; Fate, Bryan H.; Young, Henry N.; Moreno, Megan A.

    2014-01-01

    Aims Although most children with type 1 diabetes don’t achieve optimal glycemic control, no systematic method exists to identify and address self-management barriers. This study develops and validates PRISM (Problem Recognition in Illness Self-Management), a survey-based tool for efficiently identifying self-management barriers experienced by children/adolescents with diabetes and their parents. Methods Adolescents 13 years and older and parents of children 8 years and older visiting for routine diabetes management (n=425) were surveyed about self-management barriers. HbA1c was abstracted from the electronic health record. To develop PRISM, exploratory and confirmatory factor analyses were used. To assess validity, the association of PRISM scores with HbA1c was examined using linear regression. Results Factor analyses of adolescent and parent data yielded well-fitting models of self-management barriers, reflecting the following domains: 1) Understanding and Organizing Care, 2) Regimen Pain and Bother, 3) Denial of Disease and Consequences, and 4) Healthcare Team, 5) Family, or 6) Peer Interactions. All models exhibited good fit, with X2 ratios<2.21, root mean square errors of approximation<0.09, Confirmatory Fit Indices and Tucker-Lewis Indices both >0.92, and weighted root mean square residuals<1.71. Greater PRISM barrier scores were significantly associated with higher HbA1cs. Conclusions Our findings suggest at least six different domains exist within self-management barriers, nearly all of which are significantly related to HbA1c. PRISM could be used in clinical practice to identify each child and family’s unique self-management barriers, allowing existing self-management resources to be tailored to the family’s barriers, ultimately improving effectiveness of such services. PMID:24552680

  10. Taper Angle Evolution in Taiwan Accretionary Wedge

    NASA Astrophysics Data System (ADS)

    Chen, L.; Chi, W.; Liu, C.

    2011-12-01

    Liwen Chena,b, Wu-Cheng Chia, Char-Shine Liuc aInstitute of Earth Sciences, Academia Sinica, Taipei, Taiwan bInstitute of Geosciences, National Taiwan University, Taipei, Taiwan cInstitute of Oceanography, National Taiwan University, Taipei, Taiwan The critical taper model, originally developed using onland Taiwan as an example, is governed by force balance of a horizontal compressional wedge. This model has been successfully applied to many mountainous regions around the world. Among them, Taiwan is located in an oblique collision between the Luzon Arc and the Chinese Passive margin. Previous critical taper angle studies of Taiwan are mainly focusing on utilizing land data. In this study we want to extend these studies to offshore region from the subduction zone to collision zone. Here we study the varying taper angles of the double-vergent wedge derived from 1,000 km of reflection seismic profiles in both the pro-wedge and retro-wedge locations. These profiles were collected in the last two decades. For the retro-wedge, the topography slope angle changes from 2 to 8.8 degrees; some of the steep slope suggests that some part of the retrowedge is currently in a super-critical angle state. Such dramatic changes in taper angle probably strongly affect regional sedimentary processes, including slumping, in addition to structural deformation. These complex processes might even help develop a mélange or re-open a closed basin. We are currently working on studying the taper angle evolution of the pro-wedge from subduction to arc-continent collision zone in the offshore region. Though further works are needed, our preliminary results show that the evolution of wedge angles and the geometry of the wedge are closely linked and inseparable. The structures of the subducting plate might have strong influence on the deformation style of the over-riding plate. It would be interesting to combine the angle variation with the structure interpretation of the accretionary wedge

  11. Accretionary orogens through Earth history

    USGS Publications Warehouse

    Cawood, Peter A.; Kroner, A.; Collins, W.J.; Kusky, T.M.; Mooney, W.D.; Windley, B.F.

    2009-01-01

    Accretionary orogens form at intraoceanic and continental margin convergent plate boundaries. They include the supra-subduction zone forearc, magmatic arc and back-arc components. Accretionary orogens can be grouped into retreating and advancing types, based on their kinematic framework and resulting geological character. Retreating orogens (e.g. modern western Pacific) are undergoing long-term extension in response to the site of subduction of the lower plate retreating with respect to the overriding plate and are characterized by back-arc basins. Advancing orogens (e.g. Andes) develop in an environment in which the overriding plate is advancing towards the downgoing plate, resulting in the development of foreland fold and thrust belts and crustal thickening. Cratonization of accretionary orogens occurs during continuing plate convergence and requires transient coupling across the plate boundary with strain concentrated in zones of mechanical and thermal weakening such as the magmatic arc and back-arc region. Potential driving mechanisms for coupling include accretion of buoyant lithosphere (terrane accretion), flat-slab subduction, and rapid absolute upper plate motion overriding the downgoing plate. Accretionary orogens have been active throughout Earth history, extending back until at least 3.2 Ga, and potentially earlier, and provide an important constraint on the initiation of horizontal motion of lithospheric plates on Earth. They have been responsible for major growth of the continental lithosphere through the addition of juvenile magmatic products but are also major sites of consumption and reworking of continental crust through time, through sediment subduction and subduction erosion. It is probable that the rates of crustal growth and destruction are roughly equal, implying that net growth since the Archaean is effectively zero. ?? The Geological Society of London 2009.

  12. The development of folds and cleavages in slate belts by underplating in accretionary complexes: A comparison of the Kodiak Formation, Alaska and the Calaveras Complex, California

    NASA Astrophysics Data System (ADS)

    Paterson, Scott R.; Sample, James C.

    1988-08-01

    The development of folds and cleavages in slate and graywacke belts is commonly attributed to arc-continent or continent-continent collisions. However, the Kodiak Formation of southern Alaska and the Calaveras Complex of the western Sierra Nevada, California, are two slate and graywacke belts in which folds and slaty cleavages developed during simple underthrusting and underplating within accretionary wedges. The Maastrichtian Kodiak Formation is composed dominantly of coherent turbidites but includes lesser pebbly mudstone, minor conglomerate, and rare chert. The Kodiak Formation is part of a large accretionary complex that youngs in age seaward, but bedding tops generally show landward younging. A progression of structures has been determined by crosscutting relationships and includes (1) syndeformational depositional features; (2) broken formation; (3) slaty cleavage, folds, and thrust faults; (4) crenulations and crenulation cleavage; (5) late brittle thrust faults; and (6) right-lateral strike-slip faults. Broken formation, slaty cleavage, thrust faults, and folds developed during underthrusting and underplating within an accretionary wedge. Crenulations and brittle thrust faults are related to subsequent intrawedge shortening. Based on peak metamorphism in the uppermost zeolite to prehnite-pumpellyite facies, underplating occurred at a minimum depth of 10 km. The Calaveras Complex is composed of argillite, chert, graywacke, pebbly mudstone, limestone, and volcanic rocks. Its age of deposition has a maximum range from Permian to Early Jurassic. Overall, the unit appears to young westward, but local facing indicators show eastward younging of individual blocks. The sequence of structures developed in the Calaveras Complex is (1) syn-depositional olistostromes; (2) broken formation; (3) slaty cleavage, folds, and thrust faults; and (4) younger Jura-Triassic folds and crenulation cleavages. Broken formation and slaty cleavage developed during underthrusting and

  13. Structural controls on the development of submarine channel/fan systems since the Pleistocene in the accretionary wedge off SW Taiwan

    NASA Astrophysics Data System (ADS)

    Shen, Kang-Nien; Tien-Shun Lin, Andrew; Lin, Che-Chuan; Liu, Char-Shine; Wang, Yunshuen

    2016-04-01

    The accretionary wedge off SW Taiwan is the result of incipient arc-continent collision between the Luzon volcanic arc and the northern rifted margin of the South China Sea (SCS). Dynamic interactions of thrusting, folding and a rigorous sediment supply from the Taiwan mountain belts have resulted in two arrays of canyons/channels and slope-fan systems in the accretionary wedge. The Penghu canyon/fan system lies in the lower wedge and near the northern rifted margin of the SCS. The Penghu canyon is a river-fed canyon and receives sediments from southern Taiwan and SE China during eustatic lowstands. It becomes detached from river inputs during eustatic highstands as it is in the present-day. The Gaoping canyon/fan system in the south traverses both the upper slope and lower slope domains of the accretionary wedge. This system is a river-fed system during a full eustatic cycle and it drains sediments from the onshore Gaoping River. We interpreted multiple grids of multichannel seismic reflection data of MCS994, MCS1000-6, MCS1014, MCS1046 collected onboard Ocean Research I during 2012 April to 2013 August to map out thrust/fold structures and channel/fan systems in the study area. Seismic facies analyses were performed on seismic sections and key stratal surfaces of base of Pliocene and base of Pleistocene are correlated from boreholes drilled in the shelf of the northern SCS margin. Our results show that the upper Gaoping Canyon has been confined by structural ridges with limited switching of canyon courses, whereas the lower Gaoping canyon/fan system has been developed on lower slope with channel/levee deposition in multiple slope fans since early Pleistocene. Pleistocene lateral aggrading channel-and-levee systems are especially evident near the modern canyon course in the lower slope. The Penghu can/fan system in the lower accretionary wedge is also evident by seismic facies showing channel cut-and-fill, channel abandonment and channel-and-levee systems. This

  14. Timing of deformational events in the Río San Juan complex: Implications for the tectonic controls on the exhumation of high-P rocks in the northern Caribbean subduction-accretionary prism

    NASA Astrophysics Data System (ADS)

    Escuder-Viruete, Javier; Valverde-Vaquero, Pablo; Rojas-Agramonte, Yamirka; Gabites, Janet; Castillo-Carrión, Mercedes; Pérez-Estaún, Andrés

    2013-09-01

    An integrated structural, petrological and geochronological study was undertaken to constrain the tectonic history and controls on the exhumation of the high-P rocks of the Río San Juan complex in the northern Caribbean subduction-accretionary wedge. In the main structural units of the complex, microtextural analyses were performed to identify the fabrics formed at peak of metamorphism in eclogite-facies conditions and during the main retrogressive event toward the low-P amphibolite or blueschist/greenschist-facies conditions. U-Pb SHRIMP dating on zircon rims (71.3 ± 0.7 Ma) coupled with 40Ar-39Ar analyses on phengite (~ 70-69 Ma) in felsic sills placed temporal constraints on the exhumation of the Jagua Clara serpentinite-matrix mélange during the blueschist-facies stage at the early Maastrichtian. In the Cuaba unit, U-Pb TIMS zircon ages of 89.7 ± 0.1 Ma and 90.1 ± 0.2 Ma obtained for the crystallization of tonalitic/trondhjemitic melts in the lower Guaconejo and upper Jobito subunits, respectively, are similar. These ages coupled with a U-Pb SHRIMP zircon age of 87 ± 1.8 Ma obtained in a garnet amphibolite and a group of older 40Ar-39Ar cooling ages on calcic amphibole constrain the exhumation of the Guaconejo subunit from the high-P stage to the low-P stage at the ~ 90-83 Ma time interval. Further, the age data collectively supports a genetic relationship between the distributed extensional ductile shearing, the related decompression and the local partial anatexis in the subunit, at least from the Turonian-Coniacian boundary to the early Campanian. A group of younger 40Ar-39Ar ages obtained in the mylonitized amphibolites of the basal Jobito detachment zone indicates late ductile deformation and exhumation/cooling in the late Campanian to Maastrichtian (~ 75-70 Ma). Therefore, structural and age data established deformation partitioning and reworking of retrograde fabrics during ~ 20 Ma in the Cuaba unit. The different exhumation rates obtained for the

  15. Accretionary margin of north-western Hispaniola: morphology, structure and development of part of the northern Caribbean plate boundary

    USGS Publications Warehouse

    Dillon, William P.; Austin, James A., Jr.; Scanlon, K.M.; Terence, Edgar N.; Parson, L.M.

    1992-01-01

    Broad-range side-scan sonar (GLORIA) images and single- and multi-channel seismic reflection profiles demonstrate that the margin of north-western Hispaniola has experienced compression as a consequence of oblique North American-Caribbean plate convergence. Two principal morphological or structural types of accretionary wedges are observed along this margin. The first type is characterized by a gently sloping (???4??) sea floor and generally margin-parallel linear sets of sea-floor ridges that gradually deepen towards the flat Hispaniola Basin floor to the north. The ridges are caused by an internal structure consisting of broad anticlines bounded by thrust faults that dip southwards beneath Hispaniola. Anticlines form at the base of the slope and are eventually sheared and underthrust beneath the slope. In contrast, the second type of accretionary wedge exhibits a steeper (???6-16??) sea-floor slope characterized by local slumping and a more abrupt morphological transition to the adjacent basin. The internal structure appears chaotic on seismic reflection profiles and probably consists of tight folds and closely spaced faults. We suggest that changes in sea-floor declivity and internal structure may result from variations in the dip or frictional resistance of the de??collement, or possibly from changes in the cohesive strength of the wedge sediments. The observed pattern of thickening of Hispaniola Basin turbidites towards the insular margin suggests differential southwards tilting of the Hispaniola Basin strata, probably in response to North America-Caribbean plate interactions since the Early Tertiary. Based upon indirect age control from adjacent parts of the northern caribbean plate boundary, we infer a Late Eocene to Early Miocene episode of transcurrent motion (i.e. little or no tilting), an Early Miocene to Late Pliocene period of oblique convergence (i.e. increased tilt) during which the accretionary wedge began to be constructed, and a Late Pliocene to

  16. PRISM Spectrograph Optical Design

    NASA Technical Reports Server (NTRS)

    Chipman, Russell A.

    1995-01-01

    The objective of this contract is to explore optical design concepts for the PRISM spectrograph and produce a preliminary optical design. An exciting optical configuration has been developed which will allow both wavelength bands to be imaged onto the same detector array. At present the optical design is only partially complete because PRISM will require a fairly elaborate optical system to meet its specification for throughput (area*solid angle). The most complex part of the design, the spectrograph camera, is complete, providing proof of principle that a feasible design is attainable. This camera requires 3 aspheric mirrors to fit inside the 20x60 cm cross-section package. A complete design with reduced throughput (1/9th) has been prepared. The design documents the optical configuration concept. A suitable dispersing prism material, CdTe, has been identified for the prism spectrograph, after a comparison of many materials.

  17. Thermochronology of the Torlesse accretionary complex, Wellington region, New Zealand

    NASA Astrophysics Data System (ADS)

    Kamp, Peter J. J.

    2000-08-01

    The Torlesse Complex comprises several Mesozoic accretionary prism complexes together forming continental basement over large parts of New Zealand. This study focuses on the thermal history of relatively low grade graywacke rocks exposed in a transect in southern North Island that crosses the structural grain of the Torlesse Complex, including its older and younger parts. Zircon fission track (FT) ages for the Late Triassic Rakaia Terrane, which is the most inboard of the accretionary complexes, are partially annealed, some possibly reset, and may indicate early Cretaceous (134±10 Ma) cooling from maximum temperatures (Tmax), probably related to imbrication of younger complexes of the Pahau Terrane. Numerical modeling of the zircon FT ages and published 40ArA/39Ar muscovite and biotite ages for the Rakaia Terrane suggest Tmax values of 265-310°C and exhumation from depths of 10-12 km. The rocks underlying the Aorangi Range and involving the youngest accretionary complex have experienced much lower Tmax values of ≤210° and ≥110°C, bracketed by reset apatite FT ages and detrital zircon FT ages. The occurrence of a circa 100 Ma component of zircon FT ages in both the weakly and highly indurated rocks beneath the Aorangi Range, as well as in remnants of an overlying Albian accretionary slope basin (Whatarangi Formation), imply multistorey accretion and incorporation of sediment into the youngest prism. This circa 100 Ma zircon FT age component also places a maximum age on the termination of Mesozoic subduction beneath the New Zealand region. The occurrence of reset apatite FT ages across the whole of the Wellington transect indicates that at least 4 km of exhumation occurred during the late Miocene.

  18. Structural development of a high-pressure collisional accretionary wedge: The Samaná complex, Northern Hispaniola

    NASA Astrophysics Data System (ADS)

    Escuder-Viruete, Javier; Pérez-Estaún, Andrés; Gabites, Janet; Suárez-Rodríguez, Ángela

    2011-05-01

    The Samaná metamorphic complex exposes a segment of a high-pressure collisional accretionary wedge, built during Caribbean island arc-North America continental margin convergence. Combined detailed mapping, structural and metamorphic analysis, and 40Ar/39Ar geochronology show that the deformation can be divided into five main events. Early subduction-related D1 deformation and high-P/low-T M1 metamorphism under lawsonite blueschist (325-425 °C/12-18 kbar; Rincon Marbles and Santa Bárbara Schists lower structural nappes) and eclogite facies conditions (425-450 °C/18-20 kbar; Punta Balandra upper structural nappe), was followed by M2 decompression and cooling in the blueschist facies conditions during D2 folding, thrusting and nappe stacking. 40Ar/39Ar plateau ages and T-t/P-t estimations revealed Late Eocene to earliest Miocene retrograde M2 metamorphism in the different nappes for a consistent D2 top-to-the-ENE tectonic transport, which suggests a general northeastward progradation of deformation. The D3 event substantially modified the nappe stack and produced open to tight folds with amplitudes up to kilometer-scale and the D4 ductile to brittle normal shear zones and faults, and related subhorizontal folding, record a late extensional deformation, which also affects the whole nappe pile. Non-penetrative D3 and D4 fabrics indicate M3 cooling in and under the M3 greenschist-facies conditions. From the Miocene to the Present, the nappe pile was cut and laterally displaced by a D5 sinistral strike-slip and reverse fault system associated with the Septentrional fault zone.

  19. Structure and Evolution of the Accretionary Margin of Java-Sumatra. Seismic Data and Numerical Modeling Comparisons.

    NASA Astrophysics Data System (ADS)

    Kopp, H.; Hindle, D.

    2007-12-01

    We present a numerical model for the evolution of an accretionary prism along a subduction margin. We find the mechanical partitioning of the growing prism into active region, abutting against a deformable backstop, and a relatively undeformed forearc basin is a function of the double tapered basal geometry, where the dip of the detachment is assumed to be opposite above oceanic or continental lithopshere. Varying properties of both materials and detachment can be used to adjust the surface slope and hence geometry of the system, but mechanical partitioning remains essentially the same with the regions becoming broader or narrower. The model appears to closely reproduce the geometry of the Sumatra-Java prism, where a high accretion margin has produced the same distinct mechanical units. Newly prestack depth-migrated marine seismic data reveal the extent and geometry of the active deformation of the deformable backstop, and give indications of some material passing into a subduction channel below the accretionary complex. The deformable backstop appears to be composed of multiple duplex structures, but present day tectonic activity is mostly in the form of transtensive or transpressive deformation, possibly reactivating older dip-slip, accretionary structures. The numerical approach used in the simulation (distinct elements) shows great promise in modelling large deformation in situations such as accretionary prisms, and has also been adapted to incorporate the role of fluid pressure and migration in tandem with large deformation (shortening of the order of 100's of kilometres).

  20. Fate of mass-transport deposits in convergent margins: Super- or sub-critical state in accretionary- or non-accretionary slope toes

    NASA Astrophysics Data System (ADS)

    Ogawa, Y.; Kawamura, K.; Anma, R.

    2011-12-01

    (Kawamura et al., 2009 GSAB, 2011; Anma et al., 2011; Michiguchi and Ogawa, 2011 all in Springer Book). Most of them must be related to tsunami hazards in the recent ages. For the lateral variation of inside and surface of the present Nankai accretionary prism, the slope instability might also be explained by the difference in whether gravitational mass transportation works or not, depending upon the instability (supercritical) or stability (subcritical) of the slope angle. Such differences are known laterally from off western Shikoku to Tokai areas, and are probably controlled by either pore-fluid pressure difference or by the different stages for super- or sub-critical state of slope development due to a seamount or ridge subduction-collision. By careful consideration of the present trench slope topography of the Japan trench status which is the results of thrusting and mass transportation during large earthquakes, the total extent of the discussion between the instability and collapse of the trench slope for further generation of large-scale tsunamis must be understood.

  1. Composite Spectrometer Prisms

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.; Page, N. A.; Rodgers, J. M.

    1985-01-01

    Efficient linear dispersive element for spectrometer instruments achieved using several different glasses in multiple-element prism. Good results obtained in both two-and three-element prisms using variety of different glass materials.

  2. Australopithecine enamel prism patterns.

    PubMed

    Vrba, E S; Grine, F E

    1978-11-24

    Following a recent suggestion that tooth enamel prism shape differs within Hominoidea, the teeth of a number of extinct and extant hominoid species were analyzed by scanning electron microscopy. The enamel prism patterns of some gracile and robust australopithecine specimens from Sterkfontein, Swartkrans, and Kromdraai are recorded. The characteristic arrangements of enamel prisms in all modern and extinct hominoid species were found to be essentially similar. The implications of enamel prisms for phylogenetic deduction in Hominoidea are discussed. PMID:102032

  3. Development of an x-ray prism for analyzer based imaging systems

    SciTech Connect

    Bewer, Brian; Chapman, Dean

    2010-08-15

    Analyzer crystal based imaging techniques such as diffraction enhanced imaging (DEI) and multiple imaging radiography (MIR) utilize the Bragg peak of perfect crystal diffraction to convert angular changes into intensity changes. These x-ray techniques extend the capability of conventional radiography, which derives image contrast from absorption, by providing large intensity changes for small angle changes introduced from the x-ray beam traversing the sample. Objects that have very little absorption contrast may have considerable refraction and ultrasmall angle x-ray scattering contrast improving visualization and extending the utility of x-ray imaging. To improve on the current DEI technique an x-ray prism (XRP) was designed and included in the imaging system. The XRP allows the analyzer crystal to be aligned anywhere on the rocking curve without physically moving the analyzer from the Bragg angle. By using the XRP to set the rocking curve alignment rather than moving the analyzer crystal physically the needed angle sensitivity is changed from submicroradians for direct mechanical movement of the analyzer crystal to tens of milliradians for movement of the XRP angle. However, this improvement in angle positioning comes at the cost of absorption loss in the XRP and depends on the x-ray energy. In addition to using an XRP for crystal alignment it has the potential for scanning quickly through the entire rocking curve. This has the benefit of collecting all the required data for image reconstruction in a single measurement thereby removing some problems with motion artifacts which remain a concern in current DEI/MIR systems especially for living animals.

  4. Modeling Fluid Flow and Microbial Reactions in the Peru Accretionary Complex

    NASA Astrophysics Data System (ADS)

    Bekins, B. A.; Matmon, D.

    2002-12-01

    Accretionary complexes are sites where sediment compaction and deeper reactions drive large-scale flow systems that can affect global solute budgets. Extensive modeling and drilling studies have elucidated the origin of the fluids, pore pressures, duration of flow, and major flow paths in these settings. An important research goal is to quantify the effect of these flow systems on global chemical budgets of reactive solutes such as carbon. The Peru margin represents an end member setting that can serve as a basis to extend the results to other margins. The sediments are relatively high in organic carbon with an average value of 2.6%. The subduction rate at ~9 cm/yr and taper angle at 14-17° are among the largest in the world. Recent microbial studies on Ocean Drilling Program Leg 201 at the Peru accretionary margin provide many key elements needed to quantify the processes affecting organic carbon in an accretionary complex. Pore water chemistry data from Site 1230 located in the Peru accretionary prism indicate that sulfate reduction is important in the top 8 mbsf. Below this depth, methanogenesis is the dominant process and methane concentrations are among the highest measured at any site on Leg 201. The presence of high methane concentrations at shallow depths suggests that methane is transported upward in the prism by fluid flow. Measurements of in-situ pore pressures and temperatures also support the presence of upward fluid flow. A single in-situ pressure measurement at ~100 mbsf indicated an overpressure of 0.14 MPa. For a reasonable formation permeability of ~ 10-16 m2, the measured overpressure is adequate to produce flow at a rate of ~5 mm/yr. This rate is comparable to previous model estimates for flow rates in the Peru accretionary prism. In addition, curvature in the downhole temperature profile can best be explained by upward fluid flow of 1-10 mm/yr. These data are used to constrain a two-dimensional coupled fluid flow and reactive transport model

  5. Preserving with Prisms: Producing Nets

    ERIC Educational Resources Information Center

    Prummer, Kathy E.; Amador, Julie M.; Wallin, Abraham J.

    2016-01-01

    Two mathematics teachers in a small rural school decided to create a task that would engage seventh graders. The goal of the real-world activity was to help students develop geometric and spatial reasoning and to support their understanding of volume of rectangular prisms. The impetus for the task came from the teachers' desire to engage students…

  6. Flexural bending-induced plumelets and their seamounts in accretionary (Japanese-style) and collisional (Tethyan-style) orogenic belts

    NASA Astrophysics Data System (ADS)

    Hirano, N.; Dilek, Y.

    2015-12-01

    Seamounts and seamount chains are common in both the upper and lower plates of active subduction zones. Their OIB-type volcanic products are distinctly different from suprasubduction zone (arc, forearc and backarc) generated volcanic rocks in terms of their compositions and mantle sources. Tectonic accretion of such seamounts into the Japanese archipelago in the NW Pacific and into subduction-accretion complexes and active margins of continents/microcontinents within the Tethyan realm during the Cretaceous played a significant role in continental growth. Seamount assemblages comprise alkaline volcanic rocks intercalated with radiolarian and hemipelagic chert, and limestone, and may also include hypabyssal dolerite and gabbro intrusions. In the Tethyan orogenic belts these seamount rocks commonly occur as km-scale blocks in mélange units beneath the late Jurassic - Cretaceous ophiolites nappes, whereas on the Japanese islands they form discrete, narrow tectonic belts within the late Jurassic - Cretaceous accretionary prism complexes. We interpret some of these OIB occurrences in the Japanese and Tethyan mountain belts as asperities in downgoing oceanic plates that formed in <10 million years before their accretion. Their magmas were generated by decompressional melting of upwelling asthenosphere, without any significant mantle plume component, and were brought to the seafloor along deep-seated brittle fractures that developed in the flexed, downgoing lithosphere as it started bending near a trench. The modern occurrences of these "petit-spot volcanoes" are well established in the northwestern Pacific plate, off the coast of Japan. The proposed mechanism of the formation of these small seamounts better explains the lack of hotspot trails associated with their occurrence in the geological record. Magmatic outputs of such flexural bending-induced plumelets should be ubiquitious in the accretionary (Japanese-style) and collisional (Tethyan-style) orogenic belts.

  7. Accretionary lapilli: what’s holding them together?

    USGS Publications Warehouse

    Adams, Paul M.; Lynch, David K.; Buesch, David C.

    2016-01-01

    Accretionary lapilli from Tagus cone, Isla Isabela, Galápagos were analyzed using scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) techniques. Our main findings are (1) the lapilli formed and hardened in a few minutes while still aloft in the dispersing eruption column. (2) Palagonite rinds developed first on the basaltic glass clasts, and subsequently crystallized (3) The crystallization products contain submicron lamellar crystals of a clay (probably smectite) on the surfaces of basaltic glass clasts and (4) The interlocking of these lamellar clays from adjacent clasts binds and cements them together to form the accretionary lapillus. We argue that palagonite and possibly clay formation occur primarily in the presence of hot water vapor.

  8. Penta prism laser polarizer.

    PubMed

    Lotem, H; Rabinovitch, K

    1993-04-20

    A novel type of laser prism polarizer is proposed. The polarizer is characterized by a high transmission efficiency, a high optical damage threshold, and a high extinction ratio. The polarizer is shaped like a regular penta prism and, thus, it is a constant deviation angle device. Polarization effects occur upon the two internal cascade reflections in the prism. Anisotropic and Isotropic types of the polarizer are discussed. The isotropic polarizer is a prism made of a high refractive-index glass coated by multilayer polarization-type dielectric coatings. Efficient s-state polarization is obtained because of p-state leakage upon the two internal cascade reflections. The anisotropic polarizer is made of a birefringent crystal in which angular polarization splitting is obtained by the bireflectance (double-reflection) effect. Fanning of a laser beam into up to eight polarized beams is possible in a prism made of a biaxial crystal. PMID:20820335

  9. Optical switch using Risley prisms

    DOEpatents

    Sweatt, William C.; Christenson, Todd R.

    2003-04-15

    An optical switch using Risley prisms and rotary microactuators to independently rotate the wedge prisms of each Risley prism pair is disclosed. The optical switch comprises an array of input Risley prism pairs that selectively redirect light beams from a plurality of input ports to an array of output Risley prism pairs that similarly direct the light beams to a plurality of output ports. Each wedge prism of each Risley prism pair can be independently rotated by a variable-reluctance stepping rotary microactuator that is fabricated by a multi-layer LIGA process. Each wedge prism can be formed integral to the annular rotor of the rotary microactuator by a DXRL process.

  10. Optical Switch Using Risley Prisms

    SciTech Connect

    Sweatt, William C.; Christenson, Todd R.

    2005-02-22

    An optical switch using Risley prisms and rotary microactuators to independently rotate the wedge prisms of each Risley prism pair is disclosed. The optical switch comprises an array of input Risley prism pairs that selectively redirect light beams from a plurality of input ports to an array of output Risley prism pairs that similarly direct the light beams to a plurality of output ports. Each wedge prism of each Risley prism pair can be independently rotated by a variable-reluctance stepping rotary microactuator that is fabricated by a multi-layer LIGA process. Each wedge prism can be formed integral to the annular rotor of the rotary microactuator by a DXRL process.

  11. Development of an Inspection System for the Reactor Vessel/Containment Vessel of the PRISM and SAFR Liquid Metal Reactors

    SciTech Connect

    1989-02-01

    The integrity of the reactor vessel is of utmost importance in both the PRISM and SAFR concepts. The reactor vessel operates at elevated temperatures and contains molten liquid sodium. To ensure safe operation of the reactor, a periodic, visual inspection of the walls of the containment vessel is required by ASME specifications. This inspection would be conducted during a time when the reactor is shut down for refueling or maintenance. Nuclear Systems Associates, Inc. (NSA) was issued a PRDA contract by the Department of Energy to design, develop, and test a Closed Circuit Television (CCTV) camera system. The purpose of the system is to inspect the welds and wall surface of the Reactor Vessel/Container Vessel for both the PRISM and SAFR type reactors. The system was designed to function at the reactor's normal shutdown temperature, and provide a clear indication of flaws in the wall's weld seams and any cracks that might develop. The project was performed in three phases. The first phase concentrated the efforts on producing a compact camera system with the required resolution, self -contained lighting, and remote control focus and viewing angle. The proposed camera was then tested in a vessel mock-up and found to perform to required specifications at room (cold) temperatures. Simulated flaws, cracks, and a sodium leak were observed with required clarity on both a commercial and blackened stainless steel surfaces. The camera was tested with a single clear glass dome, a single coated glass dome, and a dual-glass dome covering the camera lens and mirror. The second phase of the project was conducted in two parts. The first part involved testing the vessel mock-up at elevated temperatures to verify that the required temperatures can be obtained. The mock-up was constructed with imbedded heaters and both control and indicating thermocouples. Stable operating temperatures over 400°F were achieved. During the second part of this phase, the camera was inserted into the

  12. Wide FOV wedge prism endoscope.

    PubMed

    Kim, Keri; Kim, Daeyoung; Matsumiya, Kiyoshi; Kobayashi, Etsuko; Dohi, Takeyoshi

    2005-01-01

    We.. have developed a novel robotic endoscope system. It can be used to observe a wide field of view without moving or bending the whole endoscope system. .. It consists of a rigid endoscope and two wedge prisms at the distal tip. Rotating each wedge prism respectively, we can change the direction of view. Accordingly it becomes possible to observe a wide field of view even in a small space, and suited to clinical uses because it does not damage body tissues or internal organs. .. Wedge prisms are designed to avoid vignetting which is caused by the refraction or the reflection at prisms. The endoscope has 10mm in diameter, and the drive unit is simply separable for the sterilization. In addition, since it has a simple and small drive unit, it does not obstruct surgeon or other surgery robots. The maximum movement of local field of view is 19degrees, and global field of view is 93degrees. In the evaluation experiment, we conformed that both of the image quality and the performance are acceptable. PMID:17281566

  13. Success in Developing Regions: World Records Evolution through a Geopolitical Prism

    PubMed Central

    Guillaume, Marion; Helou, Nour El; Nassif, Hala; Berthelot, Geoffroy; Len, Stéphane; Thibault, Valérie; Tafflet, Muriel; Quinquis, Laurent; Desgorces, François; Hermine, Olivier; Toussaint, Jean-François

    2009-01-01

    A previous analysis of World Records (WR) has revealed the potential limits of human physiology through athletes' personal commitment. The impact of political factors on sports has only been studied through Olympic medals and results. Here we studied 2876 WR from 63 nations in four summer disciplines. We propose three new indicators and show the impact of historical, geographical and economical factors on the regional WR evolution. The south-eastward path of weighted annual barycenter (i.e. the average of country coordinates weighting by the WR number) shows the emergence of East Africa and China in WR archives. Home WR ratio decreased from 79.9% before the second World War to 23.3% in 2008, underlining sports globalization. Annual Cumulative Proportions (ACP, i.e. the cumulative sum of the WR annual rate) highlight the regional rates of progression. For all regions, the mean slope of ACP during the Olympic era is 0.0101, with a maximum between 1950 and 1989 (0.0156). For European countries, this indicator reflects major historical events (slowdown for western countries after 1945, slowdown for eastern countries after 1990). Mean North-American ACP slope is 0.0029 over the century with an acceleration between 1950 and 1989 at 0.0046. Russia takes off in 1935 and slows down in 1988 (0.0038). For Eastern Europe, maximal progression is seen between 1970 and 1989 (0.0045). China starts in 1979 with a maximum between 1990 and 2008 (0.0021), while other regions have largely declined (mean ACP slope for all other countries  = 0.0011). A similar trend is observed for the evolution of the 10 best performers. The national analysis of WR reveals a precise and quantifiable link between the sport performances of a country, its historical or geopolitical context, and its steps of development. PMID:19862324

  14. Success in developing regions: world records evolution through a geopolitical prism.

    PubMed

    Guillaume, Marion; Helou, Nour El; Nassif, Hala; Berthelot, Geoffroy; Len, Stéphane; Thibault, Valérie; Tafflet, Muriel; Quinquis, Laurent; Desgorces, François; Hermine, Olivier; Toussaint, Jean-François

    2009-01-01

    A previous analysis of World Records (WR) has revealed the potential limits of human physiology through athletes' personal commitment. The impact of political factors on sports has only been studied through Olympic medals and results. Here we studied 2876 WR from 63 nations in four summer disciplines. We propose three new indicators and show the impact of historical, geographical and economical factors on the regional WR evolution. The south-eastward path of weighted annual barycenter (i.e. the average of country coordinates weighting by the WR number) shows the emergence of East Africa and China in WR archives. Home WR ratio decreased from 79.9% before the second World War to 23.3% in 2008, underlining sports globalization. Annual Cumulative Proportions (ACP, i.e. the cumulative sum of the WR annual rate) highlight the regional rates of progression. For all regions, the mean slope of ACP during the Olympic era is 0.0101, with a maximum between 1950 and 1989 (0.0156). For European countries, this indicator reflects major historical events (slowdown for western countries after 1945, slowdown for eastern countries after 1990). Mean North-American ACP slope is 0.0029 over the century with an acceleration between 1950 and 1989 at 0.0046. Russia takes off in 1935 and slows down in 1988 (0.0038). For Eastern Europe, maximal progression is seen between 1970 and 1989 (0.0045). China starts in 1979 with a maximum between 1990 and 2008 (0.0021), while other regions have largely declined (mean ACP slope for all other countries = 0.0011). A similar trend is observed for the evolution of the 10 best performers. The national analysis of WR reveals a precise and quantifiable link between the sport performances of a country, its historical or geopolitical context, and its steps of development. PMID:19862324

  15. High-Power Prismatic Devices for Oblique Peripheral Prisms

    PubMed Central

    Peli, Eli; Bowers, Alex R.; Keeney, Karen; Jung, Jae-Hyun

    2016-01-01

    ABSTRACT Purpose Horizontal peripheral prisms for hemianopia provide field expansion above and below the horizontal meridian; however, there is a vertical gap leaving the central area (important for driving) without expansion. In the oblique design, tilting the bases of both prism segments toward the horizontal meridian moves the field expansion area vertically and centrally (closing the central gap) while the prisms remain in the peripheral location. However, tilting the prisms results also in a reduction of the lateral field expansion. Higher prism powers are needed to counter this effect. Methods We developed, implemented, and tested a series of designs aimed at increasing the prism power to reduce the central gap while maintaining wide lateral expansion. The designs included inserting the peripheral prisms into carrier lenses that included yoked prism in the opposite direction, combination of two Fresnel segments attached at the base and angled to each other (bi-part prisms), and creating Fresnel prism–like segments from nonparallel periscopic mirror pairs (reflective prisms). Results A modest increase in lateral power was achieved with yoked-prism carriers. Bi-part combination of 36Δ Fresnel segments provided high power with some reduction in image quality. Fresnel reflective prism segments have potential for high power with superior optical quality but may be limited in field extent or by interruptions of the expanded field. Extended apical scotomas, even with unilateral fitting, may limit the utility of very high power prisms. The high-power bi-part and reflective prisms enable a wider effective eye scanning range (more than 15 degrees) into the blind hemifield. Conclusions Conventional prisms of powers higher than the available 57Δ are limited by the binocular impact of a wider apical scotoma and a reduced effective eye scanning range to the blind side. The various designs that we developed may overcome these limitations and find use in various other

  16. Prism adaptation in schizophrenia.

    PubMed

    Bigelow, Nirav O; Turner, Beth M; Andreasen, Nancy C; Paulsen, Jane S; O'Leary, Daniel S; Ho, Beng-Choon

    2006-08-01

    The prism adaptation test examines procedural learning (PL) in which performance facilitation occurs with practice on tasks without the need for conscious awareness. Dynamic interactions between frontostriatal cortices, basal ganglia, and the cerebellum have been shown to play key roles in PL. Disruptions within these neural networks have also been implicated in schizophrenia, and such disruptions may manifest as impairment in prism adaptation test performance in schizophrenia patients. This study examined prism adaptation in a sample of patients diagnosed with schizophrenia (N=91) and healthy normal controls (N=58). Quantitative indices of performance during prism adaptation conditions with and without visual feedback were studied. Schizophrenia patients were significantly more impaired in adapting to prism distortion and demonstrated poorer quality of PL. Patients did not differ from healthy controls on aftereffects when the prisms were removed, but they had significantly greater difficulties in reorientation. Deficits in prism adaptation among schizophrenia patients may be due to abnormalities in motor programming arising from the disruptions within the neural networks that subserve PL. PMID:16510223

  17. Late Paleozoic accretionary complexes on the Gondwana margin of southern Chile: Evidence from the Chonos Archipelago

    NASA Astrophysics Data System (ADS)

    Davidson, John; Mpodozis, Constantino; Godoy, Estanislao; Hervé, Francisco; Pankhurst, Robert; Brook, Maureen

    The late Paleozoic "basement" rocks that crop out along the Pacific side of the Chonos Archipelago (44°-46°S) can be divided into two north-south trending belts: (1) an eastern belt formed of submarine fan-turbidites and subordinate pelagic cherts, each containing well-preserved primary sedimentary structures, and (2) a western belt, mainly formed by strongly foliated mica schists and greenschists. Trace element contents in the cherts and greenschists indicate rocks of oceanic affinity. The structures present within the eastern rock suite are principally subiso-clinal folds (with tectonic imbrication) and locally developed zones of broken formation. The transition from these rocks into the foliated schists appears to be related to a progressive increase in metamorphism and strain associated with the development of westward verging recumbent folds and a flat-lying crenulation cleavage. It is inferred that these structures developed during the construction of a Late Carboniferous-Early Permian accretionary prism (about 260 Ma Rb-Sr ages), although sedimentation may have taken place throughout the upper Paleozoic. Rb-Sr whole-rock isochrons giving Late Jurassic to Early Cretaceous ages for some localities may indicate much later development of S2 structures. Alternatively, they may represent isotopic resetting by hydrothermal effects during the emplacement of transgressive Early Cretaceous granites, one of which gives a new Rb-Sr isochron age of 125±2Ma. This overall scenario seems to be consistent with that reported in the slightly older coastal metamorphic basement north of 34°S and equivalent or younger complexes farther south in the Madre de Dios Archipelago.

  18. Prism users guide.

    SciTech Connect

    Weirs, V. Gregory

    2012-03-01

    Prism is a ParaView plugin that simultaneously displays simulation data and material model data. This document describes its capabilities and how to use them. A demonstration of Prism is given in the first section. The second section contains more detailed notes on less obvious behavior. The third and fourth sections are specifically for Alegra and CTH users. They tell how to generate the simulation data and SESAME files and how to handle aspects of Prism use particular to each of these codes.

  19. Prism validation. Technical report

    SciTech Connect

    Daniell, R.E.; Whartenby, W.; Brown, L.D.

    1994-06-13

    This report describes the validation of PRISM, a parameterized, real-time ionospheric specification model, which was described in PL-TR-91-2299. Data were obtained from both analog and digital ionosondes, polarimeters measuring TEC, incoherent scatter radar (ISR), and in situ measurements of electron density, ion velocity, and auroral particle precipitation. Some of the data was used to drive the model while the remainder of the data was held in reserve for comparison with model output. The authors found that near ionospheric measurements (i.e., within the decorrelation length of the ionosphere), PRISM provides better than 50% improvement in f sub 0(F sub 2), N sub m(F sub 2), and TEC over the ICED, the currently operational ionospheric model at AFSFC. At distances beyond the decorrelation length, PRISM performs as well as ICED and other climatological models. They conclude that PRISM will significantly enhance the ionospheric specification capability of AFSFC.

  20. PRISM Polarimetry of Massive Stars

    NASA Astrophysics Data System (ADS)

    Kerkstra, Brennan; Lomax, Jamie R.; Bjorkman, Karen S.; Bjorkman, Jon Eric; Skiff, Brian; Covey, Kevin R.; Wisniewski, John P.

    2016-01-01

    We present the early results from our long-term, multi-epoch filter polarization survey of massive stars in and around young Galactic clusters. These BVRI polarization data were obtained using the PRISM instrument mounted on the 1.8m Perkins Telescope at Lowell Observatory. We first detail the creation of our new semi-automated polarization data reduction pipeline that we developed to process these data. Next, we present our analysis of the instrumental polarization properties of the PRISM instrument, via observations of polarized and unpolarized standard stars. Finally, we present early results on the total and intrinsic polarization behavior of several isolated, previously suggested classical Be stars, and discuss these results in the context of the larger project.BK acknowledges support from a NSF/REU at the University of Oklahoma. This program was also supported by NSF-AST 11411563, 1412110, and 1412135.

  1. PRISM project optical instrument

    NASA Technical Reports Server (NTRS)

    Taylor, Charles R.

    1994-01-01

    The scientific goal of the Passively-cooled Reconnaissance of the InterStellar Medium (PRISM) project is to map the emission of molecular hydrogen at 17.035 micrometers and 28.221 micrometers. Since the atmosphere is opaque at these infrared wavelengths, an orbiting telescope is being studied. The availability of infrared focal plane arrays enables infrared imaging spectroscopy at the molecular hydrogen wavelengths. The array proposed for PRISM is 128 pixels square, with a pixel size of 75 micrometers. In order to map the sky in a period of six months, and to resolve the nearer molecular clouds, each pixel must cover 0.5 arcminutes. This sets the focal length at 51.6 cm. In order for the pixel size to be half the diameter of the central diffraction peak at 28 micrometers would require a telescope aperture of 24 cm; an aperture of 60 cm has been selected for the PRISM study for greater light gathering power.

  2. Paleozoic accretionary orogenesis in the eastern Beishan orogen: constraints from zircon U-Pb and 40Ar/39Ar geochronology

    NASA Astrophysics Data System (ADS)

    Ao, Songjian; Xiao, Wenjiao; Windley, Brian; Mao, Qigui

    2016-04-01

    The continental growth mechanism of the Altaids in Central Asia is still in controversy between models of continuous subduction-accretion versus punctuated accretion by closure of multiple oceanic basins. The Beishan orogenic belt, located in the southern Altaids, is a natural laboratory to address this controversy. Key questions that are heavily debated are: the closure time and subduction polarity of former oceans, the emplacement time of ophiolites, and the styles of accretion and collision. This paper reports new structural data, zircon ages and Ar-Ar dates from the eastern Beishan Orogen that provide information on the accretion process and tectonic affiliation of various terranes. Our geochronological and structural results show that the younging direction of accretion was northwards and the subduction zone dipped southwards under the northern margin of the Shuangyingshan micro-continent. This long-lived and continuous accretion process formed the Hanshan accretionary prism. Our field investigations show that the emplacement of the Xiaohuangshan ophiolite was controlled by oceanic crust subduction beneath the forearc accretionary prism of the Shuangyingshan-Mazongshan composite arc to the south. Moreover, we address the age and terrane affiliation of lithologies in the eastern Beishan orogen through detrital zircon geochronology of meta-sedimentary rocks. We provide new information on the ages, subduction polarities, and affiliation of constituent structural units, as well as a new model of tectonic evolution of the eastern Beishan orogen. The accretionary processes and crustal growth of Central Asia were the result of multiple sequences of accretion and collision of manifold terranes. Reference: Ao, S.J., Xiao, W., Windley, B.F., Mao, Q., Han, C., Zhang, J.e., Yang, L., Geng, J., Paleozoic accretionary orogenesis in the eastern Beishan orogen: Constraints from zircon U-Pb and 40Ar/39Ar geochronology. Gondwana Research, doi: http://dx.doi.org/10.1016/j

  3. Less-expensive Rochon prisms

    NASA Technical Reports Server (NTRS)

    Ammann, E. O.; Massey, G. A.

    1970-01-01

    Inexpensive Rochon prisms can be produced by substituting easily polished glass for one-half of the calcite. Reciprocal polarizing properties of a conventional Rochon prism are retained, and angular separation between ordinary and extraordinary rays is the same as in all-calcite prism.

  4. Generalization of Prism Adaptation

    ERIC Educational Resources Information Center

    Redding, Gordon M.; Wallace, Benjamin

    2006-01-01

    Prism exposure produces 2 kinds of adaptive response. Recalibration is ordinary strategic remapping of spatially coded movement commands to rapidly reduce performance error. Realignment is the extraordinary process of transforming spatial maps to bring the origins of coordinate systems into correspondence. Realignment occurs when spatial…

  5. Prism Adaptation in Schizophrenia

    ERIC Educational Resources Information Center

    Bigelow, Nirav O.; Turner, Beth M.; Andreasen, Nancy C.; Paulsen, Jane S.; O'Leary, Daniel S.; Ho, Beng-Choon

    2006-01-01

    The prism adaptation test examines procedural learning (PL) in which performance facilitation occurs with practice on tasks without the need for conscious awareness. Dynamic interactions between frontostriatal cortices, basal ganglia, and the cerebellum have been shown to play key roles in PL. Disruptions within these neural networks have also…

  6. Dove prism heterodyne refractometer

    NASA Astrophysics Data System (ADS)

    Hsu, Cheng-Chih; Lee, Chia-Yun; Chu, Kuan-Ho; Wu, Tsai-Chen

    2015-10-01

    In this study, we proposed an alternative method, integrating a Dove prism and precision circular heterodyne interferometry, for measuring the refractive index and concentration of sodium chloride and hydrogen peroxide solutions with low phase error. Due to the optical properties of the Dove prism, the test light undergoes total internal reflection (TIR) at the interface between the test sample and the prism. The light beam travels in and out of the Dove prism while maintaining the same direction. Therefore, only slight alignment is required, leading to only small errors in the phase and refractive index. In this study, the phase error, refractive index error, and resolution of the concentration are approximated to be 0.003°, 2×10-5, and 1×10-3 M, respectively. The proposed method has the advantages of a simple optical configuration, ease of operation, little alignment required, and high stability, and it allows for high-precision measurement of the refractive index and concentration of the liquid sample.

  7. Acoustic dispersive prism.

    PubMed

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  8. Reflection by Porro Prisms

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2010-04-01

    Students all know that reflection from a plane mirror produces an image that is reversed right to left and so cannot be read by anyone but Leonardo da Vinci, who kept his notes in mirror writing. A useful counter-example is the Porro prism, which produces an image that is not reversed.

  9. Acoustic dispersive prism

    PubMed Central

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz–1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium. PMID:26739504

  10. Acoustic dispersive prism

    NASA Astrophysics Data System (ADS)

    Esfahlani, Hussein; Karkar, Sami; Lissek, Herve; Mosig, Juan R.

    2016-01-01

    The optical dispersive prism is a well-studied element, which allows separating white light into its constituent spectral colors, and stands in nature as water droplets. In analogy to this definition, the acoustic dispersive prism should be an acoustic device with capability of splitting a broadband acoustic wave into its constituent Fourier components. However, due to the acoustical nature of materials as well as the design and fabrication difficulties, there is neither any natural acoustic counterpart of the optical prism, nor any artificial design reported so far exhibiting an equivalent acoustic behaviour. Here, based on exotic properties of the acoustic transmission-line metamaterials and exploiting unique physical behaviour of acoustic leaky-wave radiation, we report the first acoustic dispersive prism, effective within the audible frequency range 800 Hz-1300 Hz. The dispersive nature, and consequently the frequency-dependent refractive index of the metamaterial are exploited to split the sound waves towards different and frequency-dependent directions. Meanwhile, the leaky-wave nature of the structure facilitates the sound wave radiation into the ambient medium.

  11. Tectonic and Sedimentary Interactions on the Initiation and the Architecture of the Accretionary Wedges in the Southwestern Edge of the Caribbean, off Panama and Colombia

    NASA Astrophysics Data System (ADS)

    Mercier De Lepinay, B. F.; Maurin, T.; Barat, F.; Auxietre, J.

    2013-12-01

    The structurally and stratigraphically complex area of North Panama deformed belt, Sinu-Uraba accretionary prism and south Caribbean deformed belt holds the key to understand the plate tectonic evolution of the southwestern margins of the Caribbean Sea. New geological fieldworks, sedimentary and structural analysis, detailed offshore and onshore seismic interpretation provide insights into the regional structural and stratigraphic evolution of those margins. Detailed results constraint the geodynamic history of these complex wedge architecture which registered successive changes of sedimentary supplies and gravity collapses. During the Paleocene and Eocene time, the southeastward subduction of the Caribbean plate below the northwestern edge of South America is characterized by the development of an accretionary wedge off the Caribbean margin of Colombia, due to the accumulation of a large amount of sediments provided by the Magdalena and the Sinu rivers. The Atrato river, at that time, was providing sediments to the basins restricted within the Panama Isthmus. During the Middle Miocene, the Panama Isthmus began to collide against South America, inducing the uplift of the San Jacinto/Sinu Belt in Colombia. As a consequence, the Magdalena river was deviated northward. The Sinu river was also deviated to the North and started to load the back of the the Sinu accretionary wedge which then began to collapse as convergence has ceased. In the same way, the uplift of the Darien Shear Zone, east of the Atrato basin, has deflected the sedimentary supply from the Chucunaque/Tuira basins to the northern margin of the isthmus, allowing the development of a sedimentary basin and the initiation of the North Panama Deformed Belt. Thus, on one hand, the structure of the Colombian Wedge, the Sinu Wedge and the North Panama Deformed belt, was controlled by the tectonic forces, a consequence of the convergence and progressive accretion of the Central American isthmus against the

  12. Accretionary complex structure and kinematics during Paleozoic arc continent collision in the southern Urals

    NASA Astrophysics Data System (ADS)

    Alvarez-Marron, J.; Brown, D.; Perez-Estaun, A.; Puchkov, V.; Gorozhanina, Y.

    2000-10-01

    The southern Urals contain a well-preserved accretionary complex that has overthrust the continental margin during arc-continent collision between the East European Craton (EEC) and the Magnitogorsk island arc in the Late Devonian. Within the accretionary complex, we study three tectonic units that differ in deformation style, and each provides a unique geodynamic implication. The Zilair Nappe, the largest and best exposed unit, consists of 5-6 km of syncollisional, arc-derived Upper Devonian to Lower Carboniferous polymictic and graywacke turbidites that were deposited across the continental margin and incorporated by frontal accretion into the accretionary complex. The Zilair Nappe is a bivergent thrust imbricate where the west-vergent thrusts dominate and have associated kilometer-scale ramp anticlines with well developed east-dipping axial planar cleavage. Along its eastern contact, however, the cleavage fans until it dips moderately westward and the folds are east-vergent. Following its emplacement, west-vergent, basement-involved thrusting that breached the whole accretionary complex imbricated the Zilair Nappe. The Timirovo Duplex is structurally beneath the Zilair Nappe, and outcrops for several tens of kilometers along its northwestern margin. The duplex forms a west-vergent thrust stack composed of a highly deformed and sheared Lower and Middle Devonian reef carbonates of the former EEC margin platform. These rocks were shallowly underplated at the base of the accretionary complex during emplacement over the margin. The Suvanyak Complex outcrops along the eastern contact of the Zilair Nappe, and consists of polydeformed greenschist facies metasediments of the former EEC slope that were offscraped, underplated and incorporated at the rear of the accretionary complex.

  13. Modeling consolidation and dewatering near the toe of the northern Barbados accretionary complex

    USGS Publications Warehouse

    Stauffer, P.; Bekins, B.A.

    2001-01-01

    At the toe of the northern Barbados accretionary complex, temperature and pore water chemistry data indicate that fluid flow is channeled along the de??collement and other shallow thrust faults. We examine mechanisms that may prevent consolidation and maintain high permeability over large sections of the de??collement. High-resolution bulk density data from five boreholes show that the de??collement is well consolidated at some sites while other sites remain underconsolidated. Underconsolidated de??collement behavior is associated with kilometer-scale negative-polarity seismic reflections from the de??collement plane that have been interpreted to be fluid conduits. We use a coupled fluid flow/consolidation model to simulate the loading response of a 10-km-long by 680-m-thick slice of sediment as it enters the accretionary complex. The simulations capture 185 ka (5 km) of subduction, with a load function representing the estimated effective stress of the overriding accretionary prism (3.8?? taper angle). Simulation results of bulk density in the de??collement 3.2 km arcward of the deformation front are compared with observations. The results show that persistent high pore pressures at the arcward edge of the simulation domain can explain underconsolidated behavior. The scenario is consistent with previous modeling results showing that high pore pressures can propagate intermittently along the de??collement from deeper in the complex. Simulated seaward fluxes in the de??collement (1-14 cm yr-1) lie between previous estimates from modeling studies of steady state (1 m yr-1) flow. Maximum simulated instantaneous fluid sources (2.5??10-13 s-1) are comparable to previous estimates. The simulations show minor swelling of incoming sediments (fluid sources ??? -3 ?? 1015 s-1) up to 3 km before subduction that may help to explain small-scale shearing and normal faulting proximal to the protode??collement. Copyright 2001 by the American Geophysical Union.

  14. New Light on a Prism: The Concert for All Reasons

    ERIC Educational Resources Information Center

    Linaberry, Robin

    2004-01-01

    The prism concert concept was introduced in this country at the Eastman School of Music in 1975. The development of Eastman's inaugural prism concert is commonly attributed to Donald Hunsberger and Gustav Meier, conductors of the wind ensemble and orchestra, respectively. The basic idea is that different styles of music performed by different…

  15. Diversity and biogeochemical structuring of bacterial communities across the Porangahau ridge accretionary prism, New Zealand

    USGS Publications Warehouse

    Hamdan, L.J.; Gillevet, P.M.; Pohlman, J.W.; Sikaroodi, M.; Greinert, J.; Coffin, R.B.

    2011-01-01

    Sediments from the Porangahau ridge, located off the northeastern coast of New Zealand, were studied to describe bacterial community structure in conjunction with differing biogeochemical regimes across the ridge. Low diversity was observed in sediments from an eroded basin seaward of the ridge and the community was dominated by uncultured members of the Burkholderiales. Chloroflexi/GNS and Deltaproteobacteria were abundant in sediments from a methane seep located landward of the ridge. Gas-charged and organic-rich sediments further landward had the highest overall diversity. Surface sediments, with the exception of those from the basin, were dominated by Rhodobacterales sequences associated with organic matter deposition. Taxa related to the Desulfosarcina/Desulfococcus and the JS1 candidates were highly abundant at the sulfate-methane transition zone (SMTZ) at three sites. To determine how community structure was influenced by terrestrial, pelagic and in situ substrates, sequence data were statistically analyzed against geochemical data (e.g. sulfate, chloride, nitrogen, phosphorous, methane, bulk inorganic and organic carbon pools) using the Biota-Environmental matching procedure. Landward of the ridge, sulfate was among the most significant structuring factors. Seaward of the ridge, silica and ammonium were important structuring factors. Regardless of the transect location, methane was the principal structuring factor on SMTZ communities. FEMS Microbiology Ecology ?? 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. No claim to original US government works.

  16. Mud Gas Logging In A Deep Borehole: IODP Site C0002, Nankai Trough Accretionary Prism

    NASA Astrophysics Data System (ADS)

    Toczko, S.; Hammerschmidt, S.; Maeda, L.

    2014-12-01

    Mud logging, a tool in riser drilling, makes use of the essentially "closed-circuit" drilling mud flow between the drilling platform downhole to the bit and then back to the platform for analyses of gas from the formation in the drilling mud, cuttings from downhole, and a range of safety and operational parameters to monitor downhole drilling conditions. Scientific riser drilling, with coincident control over drilling mud, downhole pressure, and returning drilling mud analyses, has now been in use aboard the scientific riser drilling vessel Chikyu since 2009. International Ocean Discovery Program (IODP) Expedition 348, as part of the goal of reaching the plate boundary fault system near ~5000 mbsf, has now extended the deep riser hole (Hole C0002 N & P) to 3058.5 mbsf. The mud gas data discussed here are from two approximately parallel boreholes, one a kick-off from the other; 860-2329 mbsf (Hole C0002N) and 2163-3058 mbsf (Hole C0002P). An approximate overlap of 166 m between the holes allows for some slight depth comparison between the two holes. An additional 55 m overlap at the top of Hole C0002P exists where a 10-5/8-inch hole was cored, and then opened to 12-1/4-inch with logging while drilling (LWD) tools (Fig. 1). There are several fault zones revealed by LWD data, confirmed in one instance by coring. One of the defining formation characteristics of Holes C0002 N/P are the strongly dipping bedding planes, typically exceeding 60º. These fault zones and bedding planes can influence the methane/ethane concentrations found in the returning drilling mud. A focused comparison of free gas in drilling mud between one interval in Hole C0002 P, drilled first with a 10 5/8-inch coring bit and again with an 12 ¼-inch logging while drilling (LWD) bit is shown. Hole C0002N above this was cased all the way from the sea floor to the kick-off section. A fault interval (in pink) was identified from the recovered core section and from LWD resistivity and gamma. The plot of methane and ethane free gas (C1 and C2; ppmv) shows that the yield of free gas (primarily methane) was greater when the LWD bit returned to open the cored hole to a greater diameter. One possible explanation for this is the time delay between coring and LWD operations; approximately 3 days passed between the end of coring and the beginning of LWD (25-28 December 2013).

  17. X-ray Interferometer Using Prism Optics

    SciTech Connect

    Suzuki, Yoshio

    2004-05-12

    Two-beam X-ray interferometer using refractive optics has been developed. A prism made of acrylic resin is used as the beam deflector for hard X-ray wavefront dividing interferometer. This configuration is the same as that of the Fresnel's bi-prism interferometer or the Leith-Upatnieks type two-beam holography in visible light region. Therefore, quantitative analysis of the degree of transversal coherence can be performed by measuring the visibility of interference fringes. It is also possible to realize two-beam holographic imaging in hard X-ray regions.

  18. Neutral density filters with Risley prisms: analysis and design.

    PubMed

    Duma, Virgil-Florin; Nicolov, Mirela

    2009-05-10

    We achieve the analysis and design of optical attenuators with double-prism neutral density filters. A comparative study is performed on three possible device configurations; only two are presented in the literature but without their design calculus. The characteristic parameters of this optical attenuator with Risley translating prisms for each of the three setups are defined and their analytical expressions are derived: adjustment scale (attenuation range) and interval, minimum transmission coefficient and sensitivity. The setups are compared to select the optimal device, and, from this study, the best solution for double-prism neutral density filters, both from a mechanical and an optical point of view, is determined with two identical, symmetrically movable, no mechanical contact prisms. The design calculus of this optimal device is developed in essential steps. The parameters of the prisms, particularly their angles, are studied to improve the design, and we demonstrate the maximum attenuation range that this type of attenuator can provide. PMID:19424388

  19. Large Erosional Features on the Cascadia Accretionary Wedge Imaged with New High-Resolution Multibeam Bathymetry and Seismic Datasets

    NASA Astrophysics Data System (ADS)

    Beeson, J. W.; Goldfinger, C.

    2013-12-01

    Utilizing new high resolution multibeam bathymetric data along with chirp sub-bottom and multichannel seismic reflection (MCS) data, we identified remarkable erosional features on the toe of the Cascadia accretionary wedge near Willapa Canyon, offshore Washington, USA. Bathymetric data was compiled from the Cascadia Open-Access Seismic Transects (COAST) cruise and from the site survey cruise for the Cascadia Initiative. These features loosely resemble slope failures of the frontal thrust, but can be distinguished from such failures by several key features: They incise the crest of the frontal thrust and encompass the landward limb; They have floors below the level of the abyssal plain, similar to plunge pool morphology; They show no evidence of landslide blocks at the base of the slope indicative of block sliding. The features where likely formed during the latest Pleistocene based on post event deposition, cross-cutting relationships with Juan de Fuca Channel and the Willapa Channel levees and wave field, and post event slip on the frontal thrust of the Cascadia accretionary prism. The Holocene levees of both Willapa Channel and Juan de Fuca Channel overlap these older features, and clearly place an upper bound on the age of the erosional features in the latest Pleistocene. A lower bound is estimated from a sub-bottom profile that images ~30 meters of post scour sediment fill. Using existing literature of Holocene and Pleistocene sedimentation rates we estimate a lower age bound between ~23,000 - 56,000 y.b.p. We also map a fault scarp within the erosional feature, with ~60 m of vertical offset. Using multi-channel seismic reflection profiles from the COAST cruise we interpret this scarp as the surface expression of the landward vergent frontal thrust fault. The apparent short duration of the erosional event along the seaward margin of the accretionary wedge, coupled with the presence of the fresh fault scarp within the erosion zone, are indicative of a dormant

  20. In situ stress magnitude and rock strength in the Nankai accretionary complex: a novel approach using paired constraints from downhole data in two wells

    NASA Astrophysics Data System (ADS)

    Huffman, K. A.; Saffer, D. M.; Dugan, B.

    2016-07-01

    We present a method to simultaneously constrain both far-field horizontal stress magnitudes ( S hmin and S Hmax) and in situ rock unconfined compressive strength (UCS), using geophysical logging data from two boreholes located 70 m apart that access the uppermost accretionary prism of the Nankai subduction zone . The boreholes sample the same sediments and are affected by the same tectonic stress field, but were drilled with different annular pressures, thus providing a unique opportunity to refine estimates of both in situ stress magnitudes and rock strength. We develop a forward model to predict the angular width of compressional wellbore failures (borehole breakouts), and identify combinations of S Hmax and UCS that best match breakout widths observed in resistivity images from the two boreholes. The method requires knowledge of S hmin, which is defined by leak-off tests conducted during drilling. Our results define a normal to strike-slip stress regime from 900 to 1386 m below seafloor, consistent with observations from seismic and core data. Our analysis also suggests that in situ values of UCS are generally slightly lower that commonly assumed on the basis of published empirical relations between UCS and P-wave velocity.

  1. Multibeam collimator uses prism stack

    NASA Technical Reports Server (NTRS)

    Minott, P. O.

    1981-01-01

    Optical instrument creates many divergent light beams for surveying and machine element alignment applications. Angles and refractive indices of stack of prisms are selected to divert incoming laser beam by small increments, different for each prism. Angles of emerging beams thus differ by small, precisely-controlled amounts. Instrument is nearly immune to vibration, changes in gravitational force, temperature variations, and mechanical distortion.

  2. Some Experiments with Thin Prisms.

    ERIC Educational Resources Information Center

    Fernando, P. C. B.

    1980-01-01

    Described are several experiments, for a course in geometrical optics or for a college physics laboratory, which have a bearing on ophthalmic optics. Experiments include the single thin prism, crossed prisms, and the prismatic power of a lens. (Author/DS)

  3. Precise Global DEM Generation by ALOS PRISM

    NASA Astrophysics Data System (ADS)

    Tadono, T.; Ishida, H.; Oda, F.; Naito, S.; Minakawa, K.; Iwamoto, H.

    2014-04-01

    The Japan Aerospace Exploration Agency (JAXA) generated the global digital elevation/surface model (DEM/DSM) and orthorectified image (ORI) using the archived data of the Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observing Satellite (ALOS, nicknamed "Daichi"), which was operated from 2006 to 2011. PRISM consisted of three panchromatic radiometers that acquired along-track stereo images. It had a spatial resolution of 2.5 m in the nadir-looking radiometer and achieved global coverage, making it a suitable potential candidate for precise global DSM and ORI generation. In the past 10 years or so, JAXA has conducted the calibration of the system corrected standard products of PRISM in order to improve absolute accuracies as well as to validate the high-level products such as DSM and ORI. In this paper, we introduce an overview of the global DEM/DSM dataset generation project, including a summary of ALOS and PRISM, in addition to the global data archive status. It is also necessary to consider data processing strategies, since the processing capabilities of the level 1 standard product and the high-level products must be developed in terms of both hardware and software to achieve the project aims. The automatic DSM/ORI processing software and its test processing results are also described.

  4. Compound prism design principles, II: triplet and Janssen prisms

    PubMed Central

    Hagen, Nathan; Tkaczyk, Tomasz S.

    2011-01-01

    Continuing the work of the first paper in this series [Appl. Opt. 50, 4998–5011 (2011)], we extend our design methods to compound prisms composed of three independent elements. The increased degrees of freedom of these asymmetric prisms allow designers to achieve greatly improved dispersion linearity. They also, however, require a more careful tailoring of the merit function to achieve design targets, and so we present several new operands for manipulating the compound prisms’ design algorithm. We show that with asymmetric triplet prisms, one can linearize the angular dispersion such that the spectral sampling rate varies by no more than 4% across the entire visible spectral range. Doing this, however, requires large prisms and causes beam compression. By adding a beam compression penalty to the merit function, we show that one can compromise between dispersion linearity and beam compression in order to produce practical systems. For prisms that do not deviate the beam, we show that Janssen prisms provide a form that maintains the degrees of freedom of the triplet and that are capable of up to 32° of dispersion across the visible spectral range. Finally, in order to showcase some of the design flexibility of three-element prisms, we also show how to design for higher-order spectral dispersion to create a two-dimensional spectrum. PMID:22423146

  5. Compound prism design principles, I

    PubMed Central

    Hagen, Nathan; Tkaczyk, Tomasz S.

    2011-01-01

    Prisms have been needlessly neglected as components used in modern optical design. In optical throughput, stray light, flexibility, and in their ability to be used in direct-view geometry, they excel over gratings. Here we show that even their well-known weak dispersion relative to gratings has been overrated by designing doublet and double Amici direct-vision compound prisms that have 14° and 23° of dispersion across the visible spectrum, equivalent to 800 and 1300 lines/mm gratings. By taking advantage of the multiple degrees of freedom available in a compound prism design, we also show prisms whose angular dispersion shows improved linearity in wavelength. In order to achieve these designs, we exploit the well-behaved nature of prism design space to write customized algorithms that optimize directly in the nonlinear design space. Using these algorithms, we showcase a number of prism designs that illustrate a performance and flexibility that goes beyond what has often been considered possible with prisms. PMID:22423145

  6. Optical design of prism-grating-prism imaging spectrometers

    NASA Astrophysics Data System (ADS)

    Zhu, Shanbing; Tang, Minxue; Ji, Yiqun; Gong, Guangbiao; Zhang, Ruirui; Shen, Weimin

    2008-12-01

    Imaging spectrometers can provide imagery and spectrum information of objects and form so-called three-dimensional spectral imagery, two spatial and one spectral dimension. Most of imaging spectrometers use conventional spectroscopic elements or systems, such as reflective diffraction gratings, prisms, filters, spatial modulated interferometers, and so on. Here a special imaging spectrometer which is based on a novel cemented Prism-Grating-Prism (PGP) is reported. Its spectroscopic element PGP consists of two prisms and a holographic transmission volume grating, which is cemented between these prisms. The two prisms mainly function as beam deviation, the grating as a disperser. In addition to the high light efficiency of the volume gratings that is required for high spectral resolution, the cementing difficulty when surface relief gratings are used can be avoided due to its voluminal characteristic. The PGP imaging spectrometer has advantages of direct vision, dispersion uniform, compactness, low cost, and facility to be used. The principle, structure, and optimized design of the PGP imaging spectrometer are given in detail. Its front collimation optics and rear focusing lenses are same so as to reduce its cost further. The spectral coverage, resolution, and track length of the designed system are respectively visible light from 400nm to 800nm, 1.6nm/pixel, and 85mm. From its performance evaluation, it is shown that the PGP imaging spectrometer has the potentiality to be used in microscopic hyperspectral imagers and hyperspectral imaging remote sensors.

  7. 21 CFR 886.1660 - Gonioscopic prism.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Gonioscopic prism. 886.1660 Section 886.1660 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior...

  8. 21 CFR 886.1660 - Gonioscopic prism.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Gonioscopic prism. 886.1660 Section 886.1660 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior...

  9. 21 CFR 886.1660 - Gonioscopic prism.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Gonioscopic prism. 886.1660 Section 886.1660 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior...

  10. 21 CFR 886.1660 - Gonioscopic prism.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Gonioscopic prism. 886.1660 Section 886.1660 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior...

  11. 21 CFR 886.1660 - Gonioscopic prism.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Gonioscopic prism. 886.1660 Section 886.1660 Food... DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1660 Gonioscopic prism. (a) Identification. A gonioscopic prism is a device that is a prism intended to be placed on the eye to study the anterior...

  12. Prism Window for Optical Alignment

    NASA Technical Reports Server (NTRS)

    Tang, Hong

    2008-01-01

    A prism window has been devised for use, with an autocollimator, in aligning optical components that are (1) required to be oriented parallel to each other and/or at a specified angle of incidence with respect to a common optical path and (2) mounted at different positions along the common optical path. The prism window can also be used to align a single optical component at a specified angle of incidence. Prism windows could be generally useful for orienting optical components in manufacture of optical instruments. "Prism window" denotes an application-specific unit comprising two beam-splitter windows that are bonded together at an angle chosen to obtain the specified angle of incidence.

  13. Prism beamswitch for radio telescopes.

    PubMed

    Payne, J M; Ulich, B L

    1978-12-01

    A dielectric prism and switching mechanism have been constructed for beamswitching a Cassegrain radio telescope. Spatially extended radio sources may be mapped without significant confusion utilizing the sensitivity and stability inherent in the conventional Dicke radiometer. PMID:18699031

  14. Cohesive Strength of Clay-Rich Sediment and Implications for Accretionary Wedge Deformation

    NASA Astrophysics Data System (ADS)

    Ikari, M.; Huepers, A.; Kopf, A.

    2011-12-01

    While studies of rock and sediment friction are common, cohesion is a component of the shear strength that is often ignored despite its potential importance for faulting and the structure of accretionary wedges. We directly measure the cohesion of clay-rich sediment by measuring its shear strength in a direct-shear apparatus with no applied effective normal stress (σn' = 0). We present measurements of cohesion for two cases: (1) After vertical consolidation only, and (2) after vertical consolidation followed by shear under applied normal stress. Under consolidation stresses of 90 kPa to 2 MPa, cohesion of both the unsheared and sheared cases depends linearly on the (previously) applied load. We interpret the cohesion measured after shearing under load to be the cohesive strength that exists throughout the shearing process, suggesting that for clay-rich materials the coefficient of internal friction should be used rather than the coefficient of sliding friction. In both sheared and unsheared cases, cohesion depends positively on clay mineral content. Cohesion is low in room-dry sediment, suggesting that it is controlled by the presence of water and may be related to the atomic charge imbalance of clays, which results in hydrogen bonding between adsorbed water molecules and the clay mineral surfaces. Coulomb wedge theory dictates that the taper angle of accretionary wedges depends on the internal friction of the wedge, the basal sliding friction of the décollement, and the amount of excess pore pressure in these locations. Cohesion is typically neglected in such analyses. In the case of the Nankai subduction zone, the accretionary wedge and décollement are composed of clay-rich sediments, meaning that cohesion should not negligible based on our experimental results. This is the case even along the décollement where active slip occurs, because sheared sediment exhibits significant cohesion that is actually higher compared to sediment that experienced only

  15. The Cimmerian accretionary wedge of Anarak, Central Iran

    NASA Astrophysics Data System (ADS)

    Zanchi, Andrea; Malaspina, Nadia; Zanchetta, Stefano; Berra, Fabrizio; Benciolini, Luca; Bergomi, Maria; Cavallo, Alessandro; Javadi, Hamid Reza; Kouhpeyma, Meyssam

    2015-04-01

    The occurrence in Iran of several ophiolite belts dating between Late Palaeozoic to Triassic poses several questions on the possible existence of various sutures marking the closure of the Palaeotethys ocean between Eurasia and this Gondwana-derived microplate. In this scenario, the Anarak region in Central Iran still represents a conundrum. Contrasting geochronological, paleontological, paleomagnetic data and reported field evidence suggest different origins for the Anarak Metamorphic Complex (AMC). The AMC is either interpreted, as: (1) relict of an accretionary wedge developed at the Eurasia margin during the Palaeotethys subduction as part of the Cimmerian suture zone of NE Iran, displaced to Central Iran by a large counter-clockwise rotation of the central Iranian blocks; (2) autochthonous unit forming a secondary branch of the main suture zone. Our structural, petrographic and geochemical data indicate that the AMC consists of several metamorphic units also including dismembered "ophiolites" which display different tectono-metamorphic evolutions. Three main ductile deformational events can be distinguished in the AMC. The Morghab and Chah Gorbeh complexes preserve a different M1 metamorphism, characterized by blueschist relics in the S1 foliation of the former unit, and greenschist assemblages in the latter. They share a subsequent similar D2 deformational and M2 metamorphic history, showing a prograde metamorphism with syn- to post-deformation growth of blueschist facies mineral assemblages on pre-existing greenschist facies associations. High pressure, low temperature (HP/LT) metamorphism responsible for the growth of sodic amphibole has been recognized also within marble lenses at the contact between the Chah Gorbeh Complex and serpentinites. Evidence of HP/LT metamorphism also occurs in glaucophane-bearing meta-pillow lavas and serpentinites, which contain antigorite and form most of the "ophiolites" within the AMC. Structural relationships show that the

  16. Evaluations of 1990 PRISM design revisions

    SciTech Connect

    Van Tuyle, G.J.; Slovik, G.C.; Chan, B.C.; Aronson, A.L.; Kennett, R.J.

    1992-03-01

    Analyses of the 1990 version of the PRISM Advanced Liquid Metal Reactor (ALMR) design are presented and discussed. Most of the calculations were performed using BNL computer codes, particularly SSC and MINET. In many cases, independent BNL calculations were compared against analyses presented by General Electric when they submitted the PRISM design revisions for evaluation by the Nuclear Regulatory Commission (NRC). The current PRISM design utilizes the metallic fuel developed by Argonne National Laboratory (ANL) which facilitates the passive/``inherent`` shutdown mechanism that acts to shut down reactor power production whenever the system overheats. There are a few vulnerabilities in the passive shutdown, with the most worrisome being the positive feedback from sodium density decreases or sodium voiding. Various postulated unscrammed events were examined by GE and/or BNL, and much of the analysis discussed in this report is focused on this category of events. For the most part, the BNL evaluations confirm the information submitted by General Electric. The principal areas of concern are related to the performance of the ternary metal fuel, and may be resolved as ANL continues with its fuel development and testing program.

  17. Risley prism universal pointing system (RPUPS)

    NASA Astrophysics Data System (ADS)

    Dixon, John; Engel, James R.; Vaillancourt, Robert; Schwarze, Craig; Potter, Kevin

    2015-09-01

    OPTRA is currently developing a Risley Prism Universal Pointing System (RPUPS): a highly customizable cued beamsteering system. The RPUPS consists of a visible or infrared cueing imager co-aligned with an optical beam steering system's pointing-field-of-regard. The cueing imager is used to identify a region-of-interest within its wide field-of-view, via a wireless tablet device. The tablet user can choose to manually or automatically, identify and track regions-of-interest. The optical beam steering system uses a matched pair of Risley Prisms to direct an interrogating optical system's instantaneous-field-of-view onto the identified region-of-interest. The tablet updates the user with real time information from both the cueing imager and the interrogating optical system. Risley prism material and geometry choices provide operating wavelength, aperture size, and field-of-regard flexibility for this front-end pointing component. Back-end components may be receive-only, transmit-only, or transmit/receive combinations. The flexibility of the RPUPS allows for mission specific customization where applications include but are not limited to: synthetic foveated imaging, spectroscopic probes and laser (LIDAR) ranging and tracking. This paper will focus on the design and anticipated applications of the RPUPS.

  18. Slope basins, headless canyons, and submarine palaeoseismology of the Cascadia accretionary complex

    USGS Publications Warehouse

    McAdoo, B.G.; Orange, D.L.; Screaton, E.; Lee, H.; Kayen, R.

    1997-01-01

    A combination of geomorphological, seismic reflection and geotechnical data constrains this study of sediment erosion and deposition at the toe of the Cascadia accretionary prism. We conducted a series of ALVIN dives in a region south of Astoria Canyon to examine the interrelationship of fluid flow and slope failure in a series of headless submarine canyons. Elevated head gradients at the inflection point of canyons have been inferred to assist in localized failures that feed sediment into a closed slope basin. Measured head gradients are an order of magnitude too low to cause seepage-induced slope failure alone; we therefore propose transient slope failure mechanisms. Intercanyon slopes are uniformly unscarred and smooth, although consolidation tests indicate that up to several metres of material may have been removed. A sheet-like failure would remove sediment uniformly, preserving the observed smooth intercanyon slope. Earthquake-induced liquefaction is a likely trigger for this type of sheet failure as the slope is too steep and short for sediment flow to organize itself into channels. Bathymetric and seismic reflection data suggest sediment in a trench slope basin between the second and third ridges from the prism's deformation is derived locally. A comparison of the amounts of material removed from the slopes and that in the basin shows that the amount of material removed from the slopes may slightly exceed the amount of material in the basin, implying that a small amount of sediment has escaped the basin, perhaps when the second ridge was too low to form a sufficient dam, or through a gap in the second ridge to the south. Regardless, almost 80% of the material shed off the slopes around the basin is deposited locally, whereas the remaining 20% is redeposited on the incoming section and will be re-accreted.

  19. Is the Chrystalls Beach Accretionary Melange a Fossil Subduction Channel Shear Zone?

    NASA Astrophysics Data System (ADS)

    Fagereng, A.; Sibson, R. H.

    2007-12-01

    In the northeast of the Hikurangi subduction margin, a 1-2 km thick layer of high Vp/Vs, low Qp and distributed microseismicity is present along the subduction megathrust interface (Eberhart-Phillips & Chadwick, 2002). This zone is interpreted as a 'subduction channel' consisting of a fluid-saturated, highly sheared mixture of trench-fill sediments, which have been subducted below (or eroded from) the accretionary prism (von Huene & Scholl, 1991). Seismic style within subduction channels may vary from large megathrust ruptures to aseismic slip associated with microseismic activity. The factors controlling these variations in style are not well understood due to the inaccessible nature of active subduction thrust interfaces. The Chrystalls Beach Complex, SE Otago, New Zealand, is a possible analogue for the seismogenic zone of an active subduction channel. This complex comprises an intensely sheared mixture of chert, terrigenous mud and sand, minor volcanogenic sediments and pillow lavas. It has a 'block-in-matrix' mélange structure, where asymmetric, dismembered beds of sand-rich competent material are enclosed within a relatively incompetent, cleaved pelitic matrix. The rock assemblage has been progressively deformed in a top-to-the-north shear zone, and is pervaded by an anastomosing network of quartz/calcite shear- and extension veins, where individual veins can be traced for tens of metres. The presence of extension veins indicates episodes where the tensile overpressure condition (Pf > σ3) was locally attained. Initially the sediments experienced compaction, volume loss and layer-parallel soft sediment shearing, developing a slaty cleavage and viscous S/C shear structures. The dense vein network developed during subsequent brittle deformation. The mineral assemblage (pumpellyite-chlorite to pumpellyite-actinolite), mica b0 spacing and illite crystallinity indicate deformation in a high pressure - low temperature environment ( ~ 3-6 kbar, ~ 200-300°C). This

  20. Rotatable prism for pan and tilt

    NASA Technical Reports Server (NTRS)

    Ball, W. B.

    1980-01-01

    Compact, inexpensive, motor-driven prisms change field of view of TV camera. Camera and prism rotate about lens axis to produce pan effect. Rotating prism around axis parallel to lens produces tilt. Size of drive unit and required clearance are little more than size of camera.

  1. PRISM3 Global Paleoclimate Reconstruction: A Global Warming Data Set

    NASA Astrophysics Data System (ADS)

    Dowsett, H. J.; Chandler, M. A.; Cronin, T. M.; Dwyer, G. S.; Haywood, A. M.; Hill, D. J.; Robinson, M. M.; Salzmann, U.; Williams, M.

    2007-12-01

    The Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project provides a conceptual model and synoptic view of the earth during the last interval considerably warmer than modern (3.3 to 3.0 Ma) through reconstruction of sea-surface temperature (SST) and other paleoenvironmental parameters. The first PRISM reconstruction, with its foundation in a global network of paleontological analyses, was completed in the early 1990s. Since then, several significant revisions have been released culminating in the PRISM2 data set. The primary goal of PRISM remains a better understanding of the Earth's climate system during the mid-Pliocene, and to that end, includes the development of digital data sets for use with climate models. The new PRISM3 reconstruction, slated to be released early in 2008, has revised SST fields based upon integration of previous and new faunal and floral analyses with new geochemical proxies and biomarkers, a revised vegetation/land cover data set utilizing the BIOME 4 vegetation classification scheme, 3-dimensional land ice distribution based upon ice-sheet model experiments, new sea level estimates based upon stable isotopes and bottom water temperatures, and revised sea-ice distribution. A deep ocean temperature reconstruction, PRISM3D, adds a 3- dimensional component, which can be used for initiating coupled ocean-atmosphere GCM simulations. PRISM3 is a collaborative effort between the U.S. Geological Survey (USGS), National Science Foundation (NSF), National Aeronautics and Space Administration (NASA), British Antarctic Survey (BAS), and several national and international academic institutions (Columbia University, Duke University, George Mason University, University of Leeds and University of Leicester).

  2. Diffractively corrected counter-rotating Risley prisms.

    PubMed

    Nie, Xin; Yang, Hongfang; Xue, Changxi

    2015-12-10

    Using the vector refraction equation and the vector diffraction equation, we obtain the expressions of the direction cosines of the refractive rays for the two wedge prisms, and the direction cosines of the diffractive rays for two wedge grisms, in which diffractive gratings were etched into the prism faces to correct the chromatic aberrations. A mathematical model between the two vector equations is proposed to compare the difference angle chromatic aberrations when the Risley prisms/grisms are rotating at different angles. We conclude that the use of diffractively corrected prisms offers a new method to correct chromatic aberrations in Risley prisms. PMID:26836873

  3. A Liquid Prism for Refractive Index Studies

    NASA Astrophysics Data System (ADS)

    Edmiston, Michael D.

    2001-11-01

    A hollow glass prism filled with liquid becomes a "liquid prism". A simple method for constructing hollow glass prisms is presented. A method is given for a demonstration that uses the liquid prism with a laser or laser pointer so the audience can observe differences in refractive index for various liquids. The demonstration provides a quick and easy determination of the sugar content of soft drinks and juices. The prism makes it easy to determine a numerical value for the refractive index of a liquid.

  4. Design and fabrication of a freeform prism array for 3D microscopy.

    PubMed

    Li, Lei; Yi, Allen Y

    2010-12-01

    Traditional microscopes have limitations in obtaining true 3D (three-dimensional) stereovision. Although some optical microscopes have been developed for 3D vision, many of them are complex, expensive, or limited to transparent samples. In this research, a freeform optical prism array was designed and fabricated to achieve 3D stereo imaging capability for microscope and machine vision applications. To form clear stereo images from multiple directions simultaneously, freeform optical surface design was applied to the prisms. In a ray tracing operation to determine the optical performance of the freeform prisms, Taylor series was used to calculate the surface shape. The virtual image spot diagrams were generated by using ray tracing methods for both the freeform prisms and the regular prisms. The results showed that all the light rays can be traced back to a single point for the freeform prism, and aberration was much smaller than that of the regular prism. The ray spots formed by the freeform prisms were adequate for image formation. Furthermore, the freeform prism array was fabricated by using a combined ultraprecision diamond turning and slow tool servo broaching process in a single, uninterrupted operation. The slow tool servo process ensured that the relative tolerance among prisms is guaranteed by the precision of the ultraprecision machine without the need for assembly. Finally 3D imaging tests were conducted to verify the freeform prism array's optical performance. The principle of the freeform prism array investigated in this research can be applied to microscopy, machine vision, robotic sensing, and many other areas. PMID:21119746

  5. Study of dose calculation on breast brachytherapy using prism TPS

    NASA Astrophysics Data System (ADS)

    Fendriani, Yoza; Haryanto, Freddy

    2015-09-01

    PRISM is one of non-commercial Treatment Planning System (TPS) and is developed at the University of Washington. In Indonesia, many cancer hospitals use expensive commercial TPS. This study aims to investigate Prism TPS which been applied to the dose distribution of brachytherapy by taking into account the effect of source position and inhomogeneities. The results will be applicable for clinical Treatment Planning System. Dose calculation has been implemented for water phantom and CT scan images of breast cancer using point source and line source. This study used point source and line source and divided into two cases. On the first case, Ir-192 seed source is located at the center of treatment volume. On the second case, the source position is gradually changed. The dose calculation of every case performed on a homogeneous and inhomogeneous phantom with dimension 20 × 20 × 20 cm3. The inhomogeneous phantom has inhomogeneities volume 2 × 2 × 2 cm3. The results of dose calculations using PRISM TPS were compared to literature data. From the calculation of PRISM TPS, dose rates show good agreement with Plato TPS and other study as published by Ramdhani. No deviations greater than ±4% for all case. Dose calculation in inhomogeneous and homogenous cases show similar result. This results indicate that Prism TPS is good in dose calculation of brachytherapy but not sensitive for inhomogeneities. Thus, the dose calculation parameters developed in this study were found to be applicable for clinical treatment planning of brachytherapy.

  6. Research on beam splitting prism in laser heterodyne interferometer

    NASA Astrophysics Data System (ADS)

    Fu, Xiu-hua; Xiong, Shi-fu; Kou, Yang; Pan, Yong-gang; Chen, Heng; Li, Zeng-yu; Zhang, Chuan-xin

    2014-08-01

    With the rapid development of optical testing technology, laser heterodyne interferometer has been used more and more widely. As the testing precision requirements continue to increase, the technical prism is an important component of heterodyne interference. The research utilizing thin film technology to improve optical performance of interferometer has been a new focus. In the article, based on the use requirements of interferometer beam splitting prism, select Ta2O5 and SiO2 as high and low refractive index materials respectively, deposit on substrate K9. With the help of TFCalc design software and Needle method, adopting electron gun evaporation and ion assisted deposition, the beam splitting prism is prepared successfully and the ratio of transmittance and reflectance for this beam splitting prism in 500~850 nm band, incident angle 45 degree is 8:2. After repeated tests, solved the difference problem of film deposition process parameters ,controlled thickness monitoring precision effectively and finally prepared the ideal beam splitting prism which is high adhesion and stable optics properties. The film the laser induced damage threshold and it meet the requirements of heterodyne interferometer for use.

  7. Development of the fecal coliform total maximum daily load using Loading Simulation Program C++ and tidal prism model in estuarine shellfish growing areas: a case study in the Nassawadox coastal embayment, Virginia.

    PubMed

    Shen, Jian; Sun, Shucun; Wang, Taiping

    2005-01-01

    In this study, a linked model system including the Loading Simulation Program C++ (LSPC) and the tidal prism water quality model (TPWQM) was proposed as an alternative tool for total maximum daily load (TMDL) studies. The feasibility of the model system was tested by a case study in the Nassawadox Creek, a Virginia tidal water shellfish growing area. The watershed model, driven by hourly precipitation, simulates hydrology and fecal coliform accumulation and transport processes in the watershed. The simulated surface runoff and subsurface flow as well as fecal coliform loads from the watershed are discharged to the tidal creek. The tidal prism model simulates fecal coliform transport in the Creek. The model results demonstrate the effectiveness in simulating hydrology and fecal coliform concentration in the watershed and its embayment. A series of sensitivity runs was conducted to estimate the load reduction necessary for fecal coliform concentration to meet the water quality standards. The model application to the Nassawadox Creek indicates that the model system is useful in developing fecal coliform TMDLs for estuarine shellfish growing areas. PMID:16134369

  8. Three timescales in prism adaptation.

    PubMed

    Inoue, Masato; Uchimura, Motoaki; Karibe, Ayaka; O'Shea, Jacinta; Rossetti, Yves; Kitazawa, Shigeru

    2015-01-01

    It has been proposed that motor adaptation depends on at least two learning systems, one that learns fast but with poor retention and another that learns slowly but with better retention (Smith MA, Ghazizadeh A, Shadmehr R. PLoS Biol 4: e179, 2006). This two-state model has been shown to account for a range of behavior in the force field adaptation task. In the present study, we examined whether such a two-state model could also account for behavior arising from adaptation to a prismatic displacement of the visual field. We first confirmed that an "adaptation rebound," a critical prediction of the two-state model, occurred when visual feedback was deprived after an adaptation-extinction episode. We then examined the speed of decay of the prism aftereffect (without any visual feedback) after repetitions of 30, 150, and 500 trials of prism exposure. The speed of decay decreased with the number of exposure trials, a phenomenon that was best explained by assuming an "ultraslow" system, in addition to the fast and slow systems. Finally, we compared retention of aftereffects 24 h after 150 or 500 trials of exposure: retention was significantly greater after 500 than 150 trials. This difference in retention could not be explained by the two-state model but was well explained by the three-state model as arising from the difference in the amount of adaptation of the "ultraslow process." These results suggest that there are not only fast and slow systems but also an ultraslow learning system in prism adaptation that is activated by prolonged prism exposure of 150-500 trials. PMID:25298383

  9. PRISM3/GISS Topographic Reconstruction

    USGS Publications Warehouse

    Sohl, Linda E.; Chandler, Mark A.; Schmunk, Robert B.; Mankoff, Ken; Jonas, Jeffrey A.; Foley, Kevin M.; Dowsett, Harry J.

    2009-01-01

    The PRISM3/GISS topographic reconstruction is one of the global data sets incorporated into a new reconstruction for the mid-Piacenzian warm interval of the Pliocene, at about 3.3 to 3.0 Ma. The PRISM3/GISS topography-gridded data set is a digitization of a graphical reconstruction, provided at 2 deg x 2 deg resolution and based on updated paleoaltimetry data and a refined land/ocean mask. Mid-Piacenzian topography as shown in this data set is generally quite similar to modern topography, with three notable differences: (1) the coastline as shown is 25 meters higher than modern sea level, reflecting the hypothesized reduction in ice sheet volume; (2) Hudson Bay is filled in to low elevation, in the absence of evidence for submergence at that time; and (3) the West Antarctic ice sheet is absent, permitting open seaways to exist in Ellsworth and Marie Byrd Lands. Two alternate ice sheet configurations with corresponding vegetation schemes are available; one is a minor modification of the PRISM2 ice reconstruction, and one is derived from the British Antarctic Survey Ice Sheet Model (BAS ISM).

  10. Inverse solutions for tilting orthogonal double prisms.

    PubMed

    Li, Anhu; Ding, Ye; Bian, Yongming; Liu, Liren

    2014-06-10

    An analytical reverse solution and actual examples are given to show how to direct a laser beam from a pair of orthogonal prisms to given targets in free space. Considering the influences of double-prism structural parameters, a lookup table method to seek the numerical reverse solution of each prism's tilting angle is also proposed for steering the double-prism orientation to track a target position located in the near field. Some case studies, as well as a specified elliptical target trajectory scanned by the cam-based driving double prisms, exhibit the significant application values of the theoretical derivation. The analytic reverse and numerical solutions can be generalized to investigate the synthesis of scanning patterns and the controlling strategy of double-prism tilting motion, the potentials of which can be explored to perform the orientation and position tracking functions in applications of precision engineering fields. PMID:24921137

  11. Error and adjustment of reflecting prisms

    NASA Astrophysics Data System (ADS)

    Mao, Wenwei

    1997-12-01

    A manufacturing error in the orientation of the working planes of a reflecting prism, such as an angle error or an edge error, will cause the optical axis to deviate and the image to lean. So does an adjustment (position error) of a reflecting prism. A universal method to be used to calculate the optical axis deviation and the image lean caused by the manufacturing error of a reflecting prism is presented. It is suited to all types of reflecting prisms. A means to offset the position error against the manufacturing error of a reflecting prism and the changes of image orientation is discussed. For the calculation to be feasible, a surface named the 'separating surface' is introduced just in front of the real exit face of a real prism. It is the image of the entrance face formed by all reflecting surfaces of the real prism. It can be used to separate the image orientation change caused by the error of the prism's reflecting surfaces from the image orientation change caused by the error of the prism's refracting surface. Based on ray tracing, a set of simple and explicit formulas of the optical axis deviation and the image lean for a general optical wedge is derived.

  12. Budding Architects: Exploring the Designs of Pyramids and Prisms

    ERIC Educational Resources Information Center

    Leavy, Aisling; Hourigan, Mairéad

    2015-01-01

    The context of students as architects is used to examine the similarities and differences between prisms and pyramids. Leavy and Hourigan use the Van Hiele Model as a tool to support teachers to develop expectations for differentiating geometry in the classroom using practical examples.

  13. Computational economy improvements in PRISM

    SciTech Connect

    Tonse, Shaheen R.; Brown, Nancy J.

    2003-01-29

    The PRISM piecewise solution mapping procedure, in which the solution of the chemical kinetic ODE system is parameterized with quadratic polynomials, is applied to CFD simulations of H{sub 2}+air combustion. Initial cost of polynomial construction is expensive, but it is recouped as the polynomial is reused. We present two methods that help us to parameterize only in places that will ultimately have high reuse. We also implement non-orthogonal Gosset factorial designs, that reduce polynomial construction costs by a factor of two over previously used orthogonal factorial designs.

  14. Arc-parallel extension and fluid flow in an ancient accretionary wedge: The San Juan Islands, Washington

    USGS Publications Warehouse

    Schermer, E.R.; Gillaspy, J.R.; Lamb, R.

    2007-01-01

    Structural analysis of the Lopez Structural Complex, a major Late Cretaceous terrane-bounding fault zone in the San Juan thrust system, reveals a sequence of events that provides insight into accretionary wedge mechanics and regional tectonics. After formation of regional ductile flattening and shear-related fabrics, the area was crosscut by brittle structures including: (1) southwest-vergent thrusts, (2) extension veins and normal faults related to northwest-southeast extension, and (3) conjugate strike-slip structures that record northwest-southeast extension and northeast-southwest shortening. Aragonite-bearing veins are associated with thrust and normal faults, but only rarely with strike-slip faults. High-pressure, low-temperature (HP-LT) minerals constrain the conditions for brittle deformation to ???20 km and <250 ??C. The presence of similar structures elsewhere indicates that the brittle structural sequence is typical of the San Juan nappes. Sustained HP-LT conditions are possible only if structures formed in an accretionary prism during active subduction, which suggests that these brittle structures record internal wedge deformation at depth and early during uplift of the San Juan nappes. The structures are consistent with orogen-normal shortening and vertical thickening followed by vertical thinning and along-strike extension. The kinematic evolution may be related initially to changes in wedge strength, followed by response to overthickening of the wedge in an unbuttressed, obliquely convergent setting. The change in vein mineralogy indicates that exhumation occurred prior to the strike-slip event. The pressure and temperature conditions and spatial and temporal extent of small faults associated with fluid flow suggest a link between these structures and the silent earthquake process. ?? 2007 Geological Society of America.

  15. Long-term temperature monitoring at the biological community site on the Nankai accretionary prism off Kii Peninsula

    NASA Astrophysics Data System (ADS)

    Goto, S.; Hamamoto, H.; Yamano, M.; Kinoshita, M.; Ashi, J.

    2008-12-01

    Nankai subduction zone off Kii Peninsula is one of the most intensively surveyed areas for studies on the seismogenic zone. Multichannel seismic reflection surveys carried out in this area revealed the existence of splay faults that branched from the subduction zone plate boundary [Park et al., 2002]. Along the splay faults, reversal of reflection polarity was observed, indicating elevated pore fluid pressure along the faults. Cold seepages with biological communities were discovered along a seafloor outcrop of one of the splay faults through submersible observations. Long-term temperature monitoring at a biological community site along the outcrop revealed high heat flow carried by upward fluid flow (>180 mW/m2) [Goto et al., 2003]. Toki et al. [2004] estimated upward fluid flow rates of 40-200 cm/yr from chloride distribution of interstitial water extracted from sediments in and around biological community sites along the outcrop. These observation results suggest upward fluid flow along the splay fault. In order to investigate hydrological nature of the splay fault, we conducted long-term temperature monitoring again in the same cold seepage site where Goto et al. [2003] carried out long-term temperature monitoring. In this presentation, we present results of the temperature monitoring and estimate heat flow carried by upward fluid flow from the temperature records. In this long-term temperature monitoring, we used stand-alone heat flow meter (SAHF), a probe-type sediment temperature recorder. Two SAHFs (SAHF-3 and SAHF-4) were used in this study. SAHF-4 was inserted into a bacterial mat, within several meters of which the previous long-term temperature monitoring was conducted. SAHF-3 was penetrated into ordinary sediment near the bacterial mat. The sub-bottom temperature records were obtained for 8 months. The subsurface temperatures oscillated reflecting bottom- water temperature variation (BTV). For sub-bottom temperatures measured with SAHF-3 (outside of the bacterial mat), we found that the effects of the BTV propagated into sediment by conduction only. By correcting the effect of the BTV, conductive heat flow estimated is higher than 100 mW/m2. Sub-bottom temperatures measured within bacterial mat (SAHF-4) except for the topmost sensor could be explained by a conduction model. The heat flow estimated based on the conduction model is similar to that measured with SAHF-3. The temperature of the topmost sensor is slightly higher than that expected from the conduction model. To explain the high temperature, upward fluid flow at a rate of 10-7 m/s order is needed. Heat flow carried by the upward fluid flow is higher than that estimated by Goto et al. [2003]. Heat flow value expected from the distribution of heat flow around this area is 70-80 mW/m2. The high heat flow values inside and outside the bacterial mat estimated in the present and previous studies may reflect upward fluid flow along the splay fault.

  16. Tectonic context of fluid venting at the toe of the eastern Nankai accretionary prism: Evidence for a shallow detachment fault

    NASA Astrophysics Data System (ADS)

    Chamot-Rooke, N.; Lallemant, S. J.; Le Pichon, X.; Henry, P.; Sibuet, M.; Boulègue, J.; Foucher, J.-P.; Furuta, T.; Gamo, T.; Glaçon, G.; Kobayashi, K.; Kuramoto, S.; Ogawa, Y.; Schultheiss, P.; Segawa, J.; Takeuchi, A.; Tarits, P.; Tokuyama, H.

    1992-04-01

    During the Kaiko-Nankai diving cruise the peak of the venting activity was located near the top of the very first anticline. The most prominent morphological feature between the mid-slope (3870 m) and the apex of the fold (3770 m) is a 20 m high cliff cutting through subhorizontal massive mudstones affected by numerous joints. The trend of this scarp is oblique to the fold axis and structurally controlled along two sharply defined NNE-SSE and E-W directions. Fresh talus and blocks found locally suggest active tectonics and recent erosion. Intense deformation is evident from strongly tilted strata restricted to the base of the cliff that we interpret as an upslope thrust. At the scale of Seabeam mapping, this thrust can be followed eastward for more than 5 km along the 3820 m isobath. Two seismic lines recorded during one of the pre-site surveys show deformation at shallow depth, including small-scale folding and thrusting affecting only the wedge-shaped top sequence. Deeper layers can be traced continuously below this sequence. We conclude that the boundary between the "piggy-back" basin and the frontal fold turbidites acts as a shallow detachment fault, and interpret the base of the cliff as the outcrop of the fault. Dense colonies ofCalyptogena clams and strongly nonlinear thermal gradients locate the major peak of fluid activity at the edge of the plateau above the main cliff. Scattered biological colonies as well as white bacterial mats and cemented chimneys were also found in a narrow belt along the base of the cliff. Fluid activity is thus closely related to the shallow detachment fault, fluid being expelled both at the outcrop of the fault and above it through the overlying strata, possibly using the very dense joint network.

  17. Comparison of frictional strength and velocity dependence between fault zones in the Nankai accretionary complex

    NASA Astrophysics Data System (ADS)

    Ikari, Matt J.; Saffer, Demian M.

    2011-04-01

    Accretionary complexes host a variety of fault zones that accommodate plate convergence and internal prism deformation, including the décollement, imbricate thrusts, and out-of-sequence thrusts or splays. These faults, especially the décollement and major splay faults, are considered to be candidates for hosting slow slip events and large magnitude earthquakes, but it is not clear what modes of slip should be expected at shallow levels or how they are related to fault rock frictional properties. We conducted laboratory experiments to measure the frictional properties of fault and wall rock from three distinct fault zone systems sampled during Integrated Ocean Drilling Program Expedition 316 and Ocean Drilling Program Leg 190 to the Nankai Trough offshore Japan. These are (1) a major out-of-sequence thrust fault, termed the "megasplay" (Site C0004), (2) the frontal thrust zone, a region of diffuse thrust faulting near the trench (Site C0007), and (3) the décollement zone sampled 2 km from the trench (Site 1174). At 25 MPa effective normal stress, at slip rates of 0.03-100 μm/s, and in the presence of brine as a pore fluid, we observe low friction (μ ≤ 0.46) for all of the materials we tested; however, the weakest samples (μ ≤ 0.30) are from the décollement zone. Material from the megasplay fault is significantly weaker than the surrounding wall rocks, a pattern not observed in the frontal thrust and décollement. All samples exhibit primarily velocity-strengthening frictional behavior, suggesting that earthquakes should not nucleate at these depths. A consistent minimum in the friction rate parameter a-b at sliding velocities of ˜1-3 μm/s (˜0.1-0.3 m/d) is observed at all three sites, suggesting that these shallow fault zones may be likely to host slow slip events.

  18. The Eurekan Orogeny: convergent intraplate deformation through accretionary tectonics?

    NASA Astrophysics Data System (ADS)

    Heron, Philip; Pysklywec, Russell; Stephenson, Randell

    2015-04-01

    The Eurekan Orogeny, which created much of the high topography (~1-2km) of Ellesmere Island and adjacent Greenland, exhibits a crustal architecture linked to intraplate orogenesis in the Cenozoic. These features occurred as a result of mountain-building processes the dynamics of which are not well understood. It is generally considered that the rotation of Greenland in the Eocene (related to sedimentary basin formation in Baffin Bay) produced compressional tectonics between Greenland and Ellesmere Island. As part of this process, the Eurekan Orogeny formed away from a traditional convergent ocean-closure plate boundary, and may represent a style of intraplate deformation. One hypothesis is the amalgamation of continental material (i.e., micro-plates) leave deformational `scars' in the crust and mantle lithosphere (specifically in the Ellesmere Island case through accretionary orogenesis in the Palaeozoic). This weakening of the lithosphere may produce episodic reactivation of faults within continental interiors. For example, lithospheric shortening at a time after continental collision could cause the previously deformed crust and mantle lithosphere to produce intraplate deformation. In this work, the geodynamic evolution of the Eurekan Orogeny and its relationship to the tectonics of the Canadian polar margin and northern Baffin Basin is explored using high-resolution thermal-mechanical numerical experiments with the modelling code SOPALE. The modelling of the High Arctic is constrained by the first-order crustal structure of the region (deduced by local gravity field and passive seismological data). Presented are suites of numerical experiments that investigate how the pre-existing lithospheric structures (both crustal and sub-crustal) control the evolution of the resulting intraplate orogen. The influence of other primary modelling parameters, such as crustal thickness and assumed rheology, is also explored. To highlight the role of surface processes on plate

  19. Payloads with Resource-Efficient Integration for Science Missions (PRISM)

    NASA Astrophysics Data System (ADS)

    Emam, O.; FitzGeorge, T.; Whittaker, A.; Wishart, A.; Fowell, S.; Prochazka, M.; Bentley, R.; Cole, R.; Brown, P.; Carr, C.; Cupido, E.; Oddy, T.

    2009-05-01

    PRISM is a collaborative industry and academia project to demonstrate the practicality of a highly integrated payload processing architecture, in order to exploit improvements in spacecraft computer performance to reduce multi-instrument payload mass and power requirements. Integrated architectures also provide opportunities for a greater degree of autonomy and advanced target selection (e.g. inter-instrument triggering). The PRISM architecture has potential advantages for missions such as EJSM (Europa Jupiter System Mission) or Solar Orbiter. The key technology objectives of PRISM are application partitioning on a qualifiable operating system, supported by the software required for fault-tolerant centralised processing, and the development of an application development environment for writing and testing instrument control applications. A working demonstrator has been implemented on a LEON3 platform, with representative payload applications from an in-situ magnetometer and a remote sensing extreme ultra-violet imager, both proposed for Solar Orbiter. PRISM is supported by the UK Science and Technology Facilities Council (STFC).

  20. Seismic reflection images of the accretionary wedge of Costa Rica

    SciTech Connect

    Shipley, T.H.; Stoffa, P.L. ); McIntosh, K.; Silver, E.A. )

    1990-05-01

    The large-scale structure of modern accretionary wedges is known almost entirely from seismic reflection investigations using single or grids of two-dimensional profiles. The authors will report on the first three-dimensional seismic reflection data volume collected of a wedge. This data set covers a 9-km-wide {times} 22-km-long {times} 6-km-thick volume of the accretionary wedge just arcward of the Middle America Trench off Costa Rica. The three-dimensional processing has improved the imaging ability of the multichannel data, and the data volume allows mapping of structures from a few hundred meters to kilometers in size. These data illustrate the relationships between the basement, the wedge shape, and overlying slope sedimentary deposits. Reflections from within the wedge define the gross structural features and tectonic processes active along this particular convergent margin. So far, the analysis shows that the subdued basement relief (horst and graben structures seldom have relief of more than a few hundred meters off Costa Rica) does affect the larger scale through going structural features within the wedge. The distribution of mud volcanoes and amplitude anomalies associated with the large-scale wedge structures suggests that efficient fluid migration paths may extend from the top of the downgoing slab at the shelf edge out into the lower and middle slope region at a distance of 50-100 km. Offscraping of the uppermost (about 45 m) sediment occurs within 4 km of the trench, creating a small pile of sediments near the trench lower slope. Underplating of parts of the 400-m-thick subducted sedimentary section begins at a very shallow structural level, 4-10 km arcward of the trench. Volumetrically, the most important accretionary process is underplating.

  1. Study of dose calculation on breast brachytherapy using prism TPS

    SciTech Connect

    Fendriani, Yoza; Haryanto, Freddy

    2015-09-30

    PRISM is one of non-commercial Treatment Planning System (TPS) and is developed at the University of Washington. In Indonesia, many cancer hospitals use expensive commercial TPS. This study aims to investigate Prism TPS which been applied to the dose distribution of brachytherapy by taking into account the effect of source position and inhomogeneities. The results will be applicable for clinical Treatment Planning System. Dose calculation has been implemented for water phantom and CT scan images of breast cancer using point source and line source. This study used point source and line source and divided into two cases. On the first case, Ir-192 seed source is located at the center of treatment volume. On the second case, the source position is gradually changed. The dose calculation of every case performed on a homogeneous and inhomogeneous phantom with dimension 20 × 20 × 20 cm{sup 3}. The inhomogeneous phantom has inhomogeneities volume 2 × 2 × 2 cm{sup 3}. The results of dose calculations using PRISM TPS were compared to literature data. From the calculation of PRISM TPS, dose rates show good agreement with Plato TPS and other study as published by Ramdhani. No deviations greater than ±4% for all case. Dose calculation in inhomogeneous and homogenous cases show similar result. This results indicate that Prism TPS is good in dose calculation of brachytherapy but not sensitive for inhomogeneities. Thus, the dose calculation parameters developed in this study were found to be applicable for clinical treatment planning of brachytherapy.

  2. Accretionary origin for the late Archean Ashuanipi Complex of Canada

    NASA Technical Reports Server (NTRS)

    Percival, J. A.

    1988-01-01

    The Ashuanipi complex is one of the largest massif granulite terrains of the Canadian Shield. It makes up the eastern end of the 2000 km long, lower-grade, east-west belts of the Archean Superior Province, permitting lithological, age and tectonic correlation. Numerous lithological, geochemical and metamorphic similarities to south Indian granulites suggest common processes and invite comparison of tectonic evolution. The Ashuanipi granulite terrain of the Cannadian Superior Province was studied in detail, and an origin through self-melting of a 55 km thick accretionary wedge seems possible.

  3. Accretionary lapilli in altered tuffs associated with coal beds.

    USGS Publications Warehouse

    Bohor, B.F.; Triplehorn, D.M.

    1984-01-01

    Accretionary lapilli (concentrically-zoned structures with featureless cores and layered rims, composed of volcanic materials) have been previously recognized in recent volcanic eruptions, and in rocks from obvious volcanic environments. The present paper extends the known occurrences to rocks of less obvious volcanic origin; in some cases the lapilli are the primary evidence for their volcanic origin. They are reported from tonsteins (clay beds associated with coals and generally interpreted as altered tuffs), and clays not associated with coals or previously interpreted as volcanic in origin, (flint in Missouri and Kentucky). -W.P.F.

  4. Porosity-formation factor and porosity-velocity relationships in Barbados prism

    NASA Astrophysics Data System (ADS)

    Erickson, Stephanie N.; Jarrard, Richard D.

    1999-07-01

    Ocean Drilling Program Leg 171A collected logging while drilling (LWD) data to investigate the porosity and velocity structure of Barbados accretionary complex. Porosity and velocity measurements were needed for interpretation of prism dynamics. However, the LWD tool string did not measure velocity, and previous velocity data from Barbados prism are scarce and generally of low quality. Furthermore, most density-based porosities are subject to errors associated with variations in smectite content. To determine porosities more accurately, we use smectite-corrected, density-based porosities to calibrate a porosity-formation factor (FF) transform, then calculate porosities from resistivity logs. We used cation exchange capacity (CEC) measurements and LWD logs to evaluate the possibility that resistivity is affected by clay conduction. The CEC data warn of potential clay conduction, especially in smectite-rich zones, but LWD data indicate that clay conduction is minor in these high-porosity sediments. Instead, tortuosity is the secondary control of FF, after porosity. By comparing resistivity-based porosities to velocities from vertical seismic profiles, we determine a porosity-velocity transform applicable to Barbados. We then use this transform to calculate velocity logs from resistivity-based porosity logs.

  5. Highly dispersive photonic band-gap prism.

    PubMed

    Lin, S Y; Hietala, V M; Wang, L; Jones, E D

    1996-11-01

    We propose the concept of a photonic band-gap (PBG) prism based on two-dimensional PBG structures and realize it in the millimeter-wave spectral regime. We recognize the highly nonlinear dispersion of PBG materials near Brillouin zone edges and utilize the dispersion to achieve strong prism action. Such a PBG prism is very compact if operated in the optical regime, ~20 mm in size for lambda ~ 700 nm, and can serve as a dispersive element for building ultracompact miniature spectrometers. PMID:19881796

  6. Multi-energy CT based on a prior rank, intensity and sparsity model (PRISM)

    PubMed Central

    Gao, Hao; Yu, Hengyong; Osher, Stanley; Wang, Ge

    2011-01-01

    We propose a compressive sensing approach for multi-energy computed tomography (CT), namely the prior rank, intensity and sparsity model (PRISM). To further compress the multi-energy image for allowing the reconstruction with fewer CT data and less radiation dose, the PRISM models a multi-energy image as the superposition of a low-rank matrix and a sparse matrix (with row dimension in space and column dimension in energy), where the low-rank matrix corresponds to the stationary background over energy that has a low matrix rank, and the sparse matrix represents the rest of distinct spectral features that are often sparse. Distinct from previous methods, the PRISM utilizes the generalized rank, e.g., the matrix rank of tight-frame transform of a multi-energy image, which offers a way to characterize the multi-level and multi-filtered image coherence across the energy spectrum. Besides, the energy-dependent intensity information can be incorporated into the PRISM in terms of the spectral curves for base materials, with which the restoration of the multi-energy image becomes the reconstruction of the energy-independent material composition matrix. In other words, the PRISM utilizes prior knowledge on the generalized rank and sparsity of a multi-energy image, and intensity/spectral characteristics of base materials. Furthermore, we develop an accurate and fast split Bregman method for the PRISM and demonstrate the superior performance of the PRISM relative to several competing methods in simulations. PMID:22223929

  7. Multi-energy CT based on a prior rank, intensity and sparsity model (PRISM).

    PubMed

    Gao, Hao; Yu, Hengyong; Osher, Stanley; Wang, Ge

    2011-11-01

    We propose a compressive sensing approach for multi-energy computed tomography (CT), namely the prior rank, intensity and sparsity model (PRISM). To further compress the multi-energy image for allowing the reconstruction with fewer CT data and less radiation dose, the PRISM models a multi-energy image as the superposition of a low-rank matrix and a sparse matrix (with row dimension in space and column dimension in energy), where the low-rank matrix corresponds to the stationary background over energy that has a low matrix rank, and the sparse matrix represents the rest of distinct spectral features that are often sparse. Distinct from previous methods, the PRISM utilizes the generalized rank, e.g., the matrix rank of tight-frame transform of a multi-energy image, which offers a way to characterize the multi-level and multi-filtered image coherence across the energy spectrum. Besides, the energy-dependent intensity information can be incorporated into the PRISM in terms of the spectral curves for base materials, with which the restoration of the multi-energy image becomes the reconstruction of the energy-independent material composition matrix. In other words, the PRISM utilizes prior knowledge on the generalized rank and sparsity of a multi-energy image, and intensity/spectral characteristics of base materials. Furthermore, we develop an accurate and fast split Bregman method for the PRISM and demonstrate the superior performance of the PRISM relative to several competing methods in simulations. PMID:22223929

  8. Subsea Gas Emissions from the Barbados Accretionary Complex

    NASA Astrophysics Data System (ADS)

    Barnard, A.; Sager, W. W.; Snow, J. E.; Max, M. D.

    2015-12-01

    We study newly identified gas plumes in the water column from the Barbados Accretionary Complex using multibeam echo soundings from cruise AT21-02. The multibeam data were used to define a region with several ~600 - 900 m tall gas plumes in the water column directly above cratered hummocky regions of the sea floor that have relatively high backscatter, at a water depth of ~1500 m. The natural gas hydrate stability zone reaches a minimum depth of ~600 m in the water column, similar to that of the tallest imaged bubble plumes, implying hydrate shells on the gas bubbles. Maximum tilt of the plume shows current shear in a direction from northwest to southeast (~128°), similar to the transport direction of North Atlantic Deep Water. The source of hydrocarbons, determined from existing geochemical data, suggests the gas source was subjacent marine Cretaceous source rocks. North-south trending faults, craters and mud volcanoes associated with the gas plumes point to the presence of a deep plumbing system and indicate that gas is a driver of mud volcanism. The widespread occurrence of seafloor morphology related to venting indicates that subsea emissions from the Barbados Accretionary Complex are substantial.

  9. Microstructures, Chemical Composition, and Viscosities of Fault-generated Friction Melts in the Shimanto Accretionary Complex, Southwest Japan: Implication for Dynamics of Earthquake Faulting in Subduction Zones

    NASA Astrophysics Data System (ADS)

    Ujiie, K.; Yamaguchi, H.

    2004-12-01

    The pseudotachylytes (PT) were recently found in the Cretaceous Shimanto accretionary complex of eastern and western Shikoku, southwest Japan, but their microstructures under a backscattered electron image, chemical composition, and effects of frictional melting on co-seismic slip in the accretionary prism remains poorly understood. The PT bearing fault is the 1-2 m thick roof thrust of a duplex structure, which bounds the off-scraped coherent turbidites above from the imbricated melange below without a thermal inversion across the fault. The fault zone consists of foliated cataclasite of sandstone-shale melange in origin and dark veins. The PT commonly occurs as brecciated fragments in dark veins. The PT matrix is transparent under plane-polarized light and is optically homogeneous under cross-polarized light, similar to glass matrix. Under a backscattered electron image, the PT clearly shows the evidences for frictional melting and subsequent rapid cooling: rounded and irregularly shaped grains and vesicles in matrix and fracturing associated with grain margins. These textural features of the PT are very similar to those of experimentally generated PT. The EPMA analysis indicates that chemical composition of the PT matrix corresponds to illite with 5.7-9.9 wt% H2O and that partially melted grains are dominated by orthoclase and quartz. This indicates that the temperatures of the PT melt could reach the breakdown temperatures of orthoclase (1150 C) and quartz (1730 C), greater than the maximum temperature recorded in host rocks (170-200 C). We calculated the viscosity of friction melt, based on the chemical composition of the PT matrix and the volume fraction and aspect ratio of grains in the PT. We considered both Arrhenian and non-Arrhenian models for viscosity calculation. Our result demonstrates that the melt viscosity is much lower than PT in continental plutonic and metamorphic rocks: 10^3 Pa s (Arrhenian model) and 10^2 Pa s (non-Arrhenian model) even at

  10. Structural geology of cuttings and cores recovered from below the Kumano forearc basin, Nankai accretionary margin of Japan: Expedition 319 of the Integrated Ocean Drilling Program (IODP)

    NASA Astrophysics Data System (ADS)

    Hayman, N. W.; Byrne, T. B.; Huftile, G.; McNeill, L. C.; Kanamatsu, T.; Saffer, D.; Araki, E.; Eguchi, N. O.; Toczko, S.; Takahashi, K.; Scientists, E.

    2009-12-01

    faults are in many cases slickensided, exhibit a range of kinematic indicators (thrust, strike-slip, and normal), and have a bimodal dip distribution, ~20° and ~60°. The younger structures may have developed during forearc development of, or beneath the Kumano basin whereas the shear zones likely formed within the frontal region of the late Miocene accretionary prism or possibly along the faulted slope apron.

  11. Advanced prism-grating-prism imaging spectrograph in online industrial applications

    NASA Astrophysics Data System (ADS)

    Vaarala, Tapio; Aikio, Mauri; Keraenen, Heimo

    1997-08-01

    Imaging spectrographs have traditionally been utilized in aerial and remote sensing applications. A novel, compact and inexpensive imaging spectrograph developed by VTT Electronics is now available. It contains a multichannel fiber optic sensor head, a dispersive prism-grating-prism (PGP) component and digital CCD matrix camera capable of area integration. In rolled steel manufacturing, a protective oil film is applied on steel to resist corrosion while in transport and storage. The main problems in the oiling machine are film thickness control and jet failures. In this application, the spectrum of fluorescence of an oil film was measured simultaneously with parallel fibers. A relatively simple calibration and analysis procedure was used to calculate the oil film thickness. On-line color control for color reproduction is essential in both consumer and industrial products. The instrument was tested and analyzed for measuring differences in color by multivariate analysis of the spectra and by color space coordinate estimation. In general, a continuous spectrum is not absolute requirement. In these two examples, filter-based measurement would probably cost less thana PGP spectrograph solution. On the other hand, by measuring the spectrum and using an advanced signal processing algorithm one production version will cover all installations in both applications. In practice, only the fiber sensor mechanics need to be modified.

  12. 21 CFR 886.1650 - Ophthalmic bar prism.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic bar prism. 886.1650 Section 886.1650...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1650 Ophthalmic bar prism. (a) Identification. An ophthalmic bar prism is a device that is a bar composed of fused prisms of gradually...

  13. 21 CFR 886.1650 - Ophthalmic bar prism.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic bar prism. 886.1650 Section 886.1650...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1650 Ophthalmic bar prism. (a) Identification. An ophthalmic bar prism is a device that is a bar composed of fused prisms of gradually...

  14. 21 CFR 886.1650 - Ophthalmic bar prism.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic bar prism. 886.1650 Section 886.1650...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1650 Ophthalmic bar prism. (a) Identification. An ophthalmic bar prism is a device that is a bar composed of fused prisms of gradually...

  15. 21 CFR 886.1650 - Ophthalmic bar prism.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic bar prism. 886.1650 Section 886.1650...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1650 Ophthalmic bar prism. (a) Identification. An ophthalmic bar prism is a device that is a bar composed of fused prisms of gradually...

  16. 21 CFR 886.1650 - Ophthalmic bar prism.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic bar prism. 886.1650 Section 886.1650...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1650 Ophthalmic bar prism. (a) Identification. An ophthalmic bar prism is a device that is a bar composed of fused prisms of gradually...

  17. An Easily Constructed Trigonal Prism Model.

    ERIC Educational Resources Information Center

    Yamana, Shukichi

    1984-01-01

    A model of a trigonal prism which is useful for teaching stereochemistry (especially of the neodymium enneahydrate ion), can be made easily by using a sealed, empty envelope. The steps necessary to accomplish this task are presented. (JN)

  18. Polarisation losses in a ring prism cavity

    SciTech Connect

    Kuryatov, V N; Sokolov, A L

    2000-02-28

    The polarisation losses in a ring cavity, formed by total-internal-reflection prisms, were analysed. All the sources of the polarisation losses are indicated and expressions for their calculation are presented. The limit to loss reduction in cavities of this kind, set by the difference between the radii of curvature of the radiation wavefront and of the refracting prism faces, was determined. (laser gyroscopes)

  19. OPERA: Objective Prism Enhanced Reduction Algorithms

    NASA Astrophysics Data System (ADS)

    Universidad Complutense de Madrid Astrophysics Research Group

    2015-09-01

    OPERA (Objective Prism Enhanced Reduction Algorithms) automatically analyzes astronomical images using the objective-prism (OP) technique to register thousands of low resolution spectra in large areas. It detects objects in an image, extracts one-dimensional spectra, and identifies the emission line feature. The main advantages of this method are: 1) to avoid subjectivity inherent to visual inspection used in past studies; and 2) the ability to obtain physical parameters without follow-up spectroscopy.

  20. Mechanics of fold-and-thrust belts and accretionary wedges Cohesive Coulomb theory

    NASA Technical Reports Server (NTRS)

    Dahlen, F. A.; Suppe, J.; Davis, D.

    1984-01-01

    A self-consistent theory for the mechanics of thin-skinned accretionary Coulomb wedges is developed and applied to the active fold-and-thrust belt of western Taiwan. The state of stress everywhere within a critical wedge is determined by solving the static equilibrium equations subject to the appropriate boundary conditions. The influence of wedge cohesion, which gives rise to a concave curvature of the critical topographic surface and affects the orientation of the principal stresses and Coulomb fracture within the wedge, is considered. The shape of the topographic surface and the angles at which thrust faults step up from the basal decollement in the Taiwanese belt is analyzed taking into account the extensive structural and fluid-pressure data available there. It is concluded that the gross geometry and structure of the Taiwan wedge are consistent with normal laboratory frictional and fracture strengths of sedimentary rocks.

  1. Accretionary rims on inclusions in the Allende meteorite

    NASA Technical Reports Server (NTRS)

    Macpherson, G. J.; Hashimoto, A.; Grossman, L.

    1985-01-01

    The origin and composition of the rim sequence on the refractory inclusion in the Allende meteorite are studied. The different textures, mineralogy, and mineral-chemistry of the four layers of the rim are described. The layers are composed of: pyroxene, needles, olivine, hedenbergite, and andradite. Tables of the element and chemical compositions of the layers are presented. The data reveals that: (1) the layers are highly porous masses of euhedral crystals with no intergrowth; (2) layers contain highly disequilibrium mineral assemblages; and (3) the thickness of the layers varies with the underlying topography. These results support the theory that rim structures are accretionary aggregates formed from accretion of independently grown particles onto the surface of inclusions. The formation of the grains in the layers and matrix from nebular condensates is studied.

  2. Accretionary rims on inclusions in the Allende meteorite

    NASA Astrophysics Data System (ADS)

    MacPherson, G. J.; Hashimoto, A.; Grossman, L.

    1985-11-01

    The origin and composition of the rim sequence on the refractory inclusion in the Allende meteorite are studied. The different textures, mineralogy, and mineral-chemistry of the four layers of the rim are described. The layers are composed of: pyroxene, needles, olivine, hedenbergite, and andradite. Tables of the element and chemical compositions of the layers are presented. The data reveals that: (1) the layers are highly porous masses of euhedral crystals with no intergrowth; (2) layers contain highly disequilibrium mineral assemblages; and (3) the thickness of the layers varies with the underlying topography. These results support the theory that rim structures are accretionary aggregates formed from accretion of independently grown particles onto the surface of inclusions. The formation of the grains in the layers and matrix from nebular condensates is studied.

  3. Cavity Enhanced Absorption Spectroscopy Using a Broadband Prism Cavity and a Supercontinuum Source

    NASA Astrophysics Data System (ADS)

    Johnston, Paul S.; Lehmann, Kevin K.

    2009-06-01

    The multiplex advantage of current cavity enhanced spectrometers is limited by the high reflectivity bandwidth of the mirrors used to construct the high finesse cavity. Previously, we reported the design and construction of a new spectrometer that circumvents this limitation by utilizing Brewster^{,}s angle prism retroreflectors. The prisms, made from fused silica and combined with a supercontinuum source generated by pumping a highly nonlinear photonic crystal fiber, yields a spectral window ranging from 500 nm to 1750 nm. Recent progress in the instruments development will be discussed, including work on modeling the prism cavity losses, alternative prism material for use in the UV and mid-IR spectral regions, and a new high power supercontinuum source based on mode-locked picosecond laser.

  4. A portable direct view configuration prism spectrometer using a double Amici prism

    NASA Astrophysics Data System (ADS)

    Sun, Lanjun; Zhang, Yanchao; Tian, Zhaoshuo; Ren, Xiuyun; Fu, Shiyou

    2015-10-01

    In this paper, we present a prism spectrometer that exploits a double Amici prism dispersion structure. The system consists of a slit, a collimating lens, a double Amici prism, an imaging lens and a CCD. The incident light enter into slit, and then is paralleled by a collimating lens to the double Amici prism. The double Amici prism is used to realize spectral dispersion. The dispersed light is collected by an imaging lens and image on the photosensitive surface of the CCD. The dispersion resolution is theoretical analyzed from the ray tracing point of view. In addition, the imaging position on CCD element at different wavelength is presented according to nonlinear curve of dispersion. The designed prism spectrometer can obtain a high light throughput and less optical distortion spectrum in the spectral range of 370-700nm. In experiment, we measured the spectral resolution of the designed prism spectrometer at five wavelength used a grating monochromator. The designed in-line, direct view configuration prism spectrometer owns the advantages of high light throughput, less optical distortions, compact structure, small volume and easy operation, which has important role in application of laser spectral measurement especially laser remote sensing spectral detection.

  5. Origin and evolution of fluids from mud volcanoes in the Barbados accretionary complex

    NASA Astrophysics Data System (ADS)

    Godon, Arnaud; Jendrzejewski, Nathalie; Castrec-Rouelle, Maryse; Dia, Aline; Pineau, Françoise; Boulègue, Jacques; Javoy, Marc

    2004-05-01

    A large collection of fluids (54 interstitial fluids and four expelled fluids) were sampled at the Manon site, at the outer edge of the Barbados accretionary complex. These warm fluids (up to 20°C) are expelled by sub-marine (5000 mbsl) mud volcanoes consisting of diapirs (unchanneled flow) and diatremes (channeled). Chlorine stable isotope ratios of these fluids were measured by IRMS with a reproducibility of ± 0.05‰ (1σ) versus SMOC (Standard Mean Ocean Chloride). A large range of δ 37Cl between -5.3‰ and +0.1‰ is observed. Data from each volcanic structure describe a mixing between seawater and a low-δ 37Cl fluid. The whole set of data is interpreted as the result of a mixing between two deep components and seawater. The two deep fluids are chemically distinct (e.g., in Ca, Mg, K, Li, Sr and Br contents and Br/Cl ratio). They display low and significantly different 87Sr/ 86Sr ratios (0.707790 and 0.707892, respectively) and δ 37Cl values (-4.51 and -5.24‰, respectively). Physicochemical processes such as mineralogical transformation, diffusion, compaction or ion filtration are known to fractionate chlorine stable isotopes and can produce fluids with negative δ 37Cl values. Ion filtration due to sediment compaction appears to be the more likely process to explain the negative δ 37Cl values observed at the Manon site. A model for the generation of these signatures is proposed where a residual negative δ 37Cl fluid reservoir is created at the bottom of the prism or the sediment pile. Further compaction/fracturing and/or dewatering of the slab may flush out these fluids and focus them towards the décollement zone. Mixing between the fluids and ultimately with seawater and water released during gas hydrate destabilizations may explain the data set within the individual cores and between the different structures.

  6. Stress states at site C0002, Nankai accretionary wedge, down to 2000 m below seafloor

    NASA Astrophysics Data System (ADS)

    Chang, Chandong; Song, Insun; Lee, Hikweon

    2015-04-01

    The boreholes drilled at site C0002 under the Nankai Trough Seismogenic Zone Experiment project, southwest Japan were used to estimate in situ stress states that prevail in the plate interface region between Philippine Sea plate and the Eurasian plate. The depth covered in this study is from seafloor down to ~2000 meter below seafloor (mbsf), somewhat shallow compared to the depths of the megasplay fault (~5000 mbsf) and the plate interface (~6800 mbsf). However, the shallow stress may reflect some tectonic processes prevailing in this region and may give some insight into tectonic settings. Multiple techniques of borehole observations and borehole tests were used to estimate the magnitudes and the orientations of the stresses. The borehole breakouts in the vertical boreholes indicate a consistent orientation (margin-parallel) of the maximum horizontal principal stress (SHmax) throughout the depths. The analysis on the geometry (or azimuthal span) of borehole breakouts and rock strengths (from log-based estimations) suggests that the stress states in the upper forearc basin sediments above the unconformity (~980 mbsf) are constrained to be in favor of normal faulting (vertical stress (Sv) > SHmax > least horizontal stress (Shmin)). The stress states in the old accretionary prism below the unconformity down to ~1400 mbsf are possibly varying with depth between normal, strike-slip and reverse faulting favored stress regimes. At depths below 1400 mbsf, occurrences of borehole stress indicators (breakouts and drilling-induced tensile fractures (DITFs)) are limited due to optimally controlled mud pressures. Two sets of breakouts (1616 and 1862 mbsf) and DITFs (1648 and 1884 mbsf) were jointly used to constrain stress states there, which yielded that Shmin is 79-85% of Sv and SHmax is nearly equal to Sv, suggesting a mixed stress regime for normal and strike-slip faulting (Sv ~ SHmax > Shmin). The range of constrained Shmin is consistent with the results from leak

  7. The PRISM3D paleoenvironmental reconstruction

    USGS Publications Warehouse

    Dowsett, H.; Robinson, M.; Haywood, A.M.; Salzmann, U.; Hill, Daniel; Sohl, L.E.; Chandler, M.; Williams, Mark; Foley, K.; Stoll, D.K.

    2010-01-01

    The Pliocene Research, Interpretation and Synoptic Mapping (PRISM) paleoenvironmental reconstruction is an internally consistent and comprehensive global synthesis of a past interval of relatively warm and stable climate. It is regularly used in model studies that aim to better understand Pliocene climate, to improve model performance in future climate scenarios, and to distinguish model-dependent climate effects. The PRISM reconstruction is constantly evolving in order to incorporate additional geographic sites and environmental parameters, and is continuously refined by independent research findings. The new PRISM three dimensional (3D) reconstruction differs from previous PRISM reconstructions in that it includes a subsurface ocean temperature reconstruction, integrates geochemical sea surface temperature proxies to supplement the faunal-based temperature estimates, and uses numerical models for the first time to augment fossil data. Here we describe the components of PRISM3D and describe new findings specific to the new reconstruction. Highlights of the new PRISM3D reconstruction include removal of Hudson Bay and the Great Lakes and creation of open waterways in locations where the current bedrock elevation is less than 25m above modern sea level, due to the removal of the West Antarctic Ice Sheet and the reduction of the East Antarctic Ice Sheet. The mid-Piacenzian oceans were characterized by a reduced east-west temperature gradient in the equatorial Pacific, but PRISM3D data do not imply permanent El Niño conditions. The reduced equator-to-pole temperature gradient that characterized previous PRISM reconstructions is supported by significant displacement of vegetation belts toward the poles, is extended into the Arctic Ocean, and is confirmed by multiple proxies in PRISM3D. Arctic warmth coupled with increased dryness suggests the formation of warm and salty paleo North Atlantic Deep Water (NADW) and a more vigorous thermohaline circulation system that may

  8. How to Get the Full Prism Effect.

    PubMed

    Pochopien, Klaudia; Fahle, Manfred

    2015-08-01

    We investigate how the immediate correction effect decreases mispointing under prisms. Subjects performed rhythmic pointing movements under different conditions with horizontally shifting prisms. Even the first (initial) pointing error is much smaller than the prismatic shift, a phenomenon called the immediate correction effect. Knowledge about the structure of the room and of objects in the room obtained before the prisms were worn may limit the amount of the prismatic displacement perceived. We therefore compared the direct prism effect as well as prismatic adaptation with room illumination switched on versus switched off. Our 44 subjects participated in two experiments, with varying amounts of information about room structure available. The results show a direct effect corresponding to the optical power of the prisms in the dark condition, when in addition body position was slightly rotated in direction of the prismatic shift. But even in the dark, a significant immediate correction effect arises with the fixed body position. The largest immediate correction amounting to almost half of optical displacement arose in the standard condition of bright light and fixed body position. PMID:27433319

  9. How to Get the Full Prism Effect

    PubMed Central

    Fahle, Manfred

    2015-01-01

    We investigate how the immediate correction effect decreases mispointing under prisms. Subjects performed rhythmic pointing movements under different conditions with horizontally shifting prisms. Even the first (initial) pointing error is much smaller than the prismatic shift, a phenomenon called the immediate correction effect. Knowledge about the structure of the room and of objects in the room obtained before the prisms were worn may limit the amount of the prismatic displacement perceived. We therefore compared the direct prism effect as well as prismatic adaptation with room illumination switched on versus switched off. Our 44 subjects participated in two experiments, with varying amounts of information about room structure available. The results show a direct effect corresponding to the optical power of the prisms in the dark condition, when in addition body position was slightly rotated in direction of the prismatic shift. But even in the dark, a significant immediate correction effect arises with the fixed body position. The largest immediate correction amounting to almost half of optical displacement arose in the standard condition of bright light and fixed body position. PMID:27433319

  10. Seamount subduction to the Nankai accretionary wedge and its impact on methane hydrate accumulation: insights from analogue and numerical models

    NASA Astrophysics Data System (ADS)

    Yamada, Y.; Nagamura, N.; Baba, K.; Matsuoka, T.

    2006-12-01

    Seamount sudbuction is a common feature at convergent plate margins and several examples can also be seen at the Nankai wedge, but its impact on methane hydrate accumulation has not fully described. In order to understand the accumulation mechanism of methane hydrate, the key issue would be the fluid flow within the sediments. The fluid flow can be classified into two types; the diffusive flow by intergranular porosity and the focused flow along faults (Baba and Yamada, 2004). The diffusive flow can be modeled by conventional reservoir simulator type of approaches, but the focused flow along faults may be difficult. One possible scenario was suggested by Sibson (1995) that fluid may migrate along a fault surface when it slipped (breakage of seal). Following the idea, the focused fluid flow can be evaluated by fault activity that can be modeled and examined by analogue experiments and numerical simulations (Yamada et al., submitted). This research employed analogue experiments that used granular materials (dry sand and glass beads) and numerical simulations that approximate the geologic body as particles (distinct element method). The analogue model results are further analyzed by optical image correlation technique, PIV, to extract faulting events in detail. By using the same tectonic model of sea mount subduction to an accretionary prism, we examined the deformation process particularly the faulting by these two techniques. The results of the analogue experiments and numerical simulations are basically the same, apart from the reproducibility of small structures influenced by the particle size. The models suggest that a sea mount subduction causes segmentation of wedge formation. The segmentation of wedge also produces two types of fault systems; one formed before sea mount subduction and the other afterward. The geometry of these faults illustrates that the fluid from the deeper segment of the sedimentary pile may focus on the faults that formed after sudbuction

  11. Adjustable planar lightguide solar concentrators with liquid-prism structure

    NASA Astrophysics Data System (ADS)

    Tsai, Meng-Che; Whang, Allen Jong-Woei; Lee, Tsung-Xian; Chen, Yi-Yung

    2013-03-01

    Research interests on sunlight applications are booming in recent years, due to the worldwide green-energy trends. Either using PV cells to store sunlight then convert to electricity, or to use sunlight for direct illumination source are among the many research projects which deserve investigation. In this research, we focus a design combined the above two features together: direct sunlight illumination, and store the sunlight for later usage. Our design structure is as follows: 1. On the surface of outer layer, we use the liquid-prism structure to increase the angle tolerance range of solar concentrator; 2. Combine the micro structure of the solid-state prism and aspheric surfaces to produce a planar light guide structure, which compresses the plane light source into line light source, then guide the light into solar cells area; 3. Design a light switch using the liquid-prism of inside layer, and guides the sunlight into solar cells channel or indoor illumination channel. We apply it in the NLIS® developed at NTUST, not only retain the advantages of the static concentrator modules, but also eliminate the complex procedure of transmitting and emitting, reduce the loss and cost of energy transfer.

  12. APEX - the Hyperspectral ESA Airborne Prism Experiment

    PubMed Central

    Itten, Klaus I.; Dell'Endice, Francesco; Hueni, Andreas; Kneubühler, Mathias; Schläpfer, Daniel; Odermatt, Daniel; Seidel, Felix; Huber, Silvia; Schopfer, Jürg; Kellenberger, Tobias; Bühler, Yves; D'Odorico, Petra; Nieke, Jens; Alberti, Edoardo; Meuleman, Koen

    2008-01-01

    The airborne ESA-APEX (Airborne Prism Experiment) hyperspectral mission simulator is described with its distinct specifications to provide high quality remote sensing data. The concept of an automatic calibration, performed in the Calibration Home Base (CHB) by using the Control Test Master (CTM), the In-Flight Calibration facility (IFC), quality flagging (QF) and specific processing in a dedicated Processing and Archiving Facility (PAF), and vicarious calibration experiments are presented. A preview on major applications and the corresponding development efforts to provide scientific data products up to level 2/3 to the user is presented for limnology, vegetation, aerosols, general classification routines and rapid mapping tasks. BRDF (Bidirectional Reflectance Distribution Function) issues are discussed and the spectral database SPECCHIO (Spectral Input/Output) introduced. The optical performance as well as the dedicated software utilities make APEX a state-of-the-art hyperspectral sensor, capable of (a) satisfying the needs of several research communities and (b) helping the understanding of the Earth's complex mechanisms.

  13. Optical system design of the Dyson imaging spectrometer based on the Fery prism

    NASA Astrophysics Data System (ADS)

    Pei, Linlin; Xiangli, Bin; Lv, Qunbo; Shao, Xiaopeng

    2016-08-01

    Imaging spectrometer has obtained wide development since rich feature information can be obtained by it; now, we focus on its high spectral resolution and miniaturization. In this paper, we design the Dyson imaging spectrometer system based on Fery prism. The average spectral resolution is 4.3 nm and the structure of the total length is 229 mm. It is a small, high-spectrometer imaging system. The front and rear surface of the traditional prism are plane, but the surfaces of the Fery prism are spherical, which can provide some optical power to realize imaging function and produce the dispersion effect. The Fery prism does not need to be placed in the parallel optical path, which simplifies the collimator lens and the imaging lens and are necessary in the prism spectrometer, making it possible to obtain a compact spectrometer. Full-spectrum transmittance of the prism is up to 94 %. Compared to the convex grating, the energy efficiency is greatly improved, and the free spectral range is wider, and its dispersion will not bring higher-order spectral aliasing problem. The small high spectrometer only includes two components. Its spectral range is from 400 to 1000 nm, covering the near-ultraviolet to near-infrared. The various aberrations of the typical spectrum are corrected. The spectrometer is excellent in performance.

  14. Application of derivative matrices of skew rays to design of compound dispersion prisms.

    PubMed

    Lin, Psang Dain

    2016-09-01

    Numerous optimization methods have been developed in recent decades for optical system design. However, these methods rely heavily on ray tracing and finite difference techniques to estimate the derivative matrices of the rays. Consequently, the accuracy of the results obtained from these methods is critically dependent on the incremental step size used in the tuning stage. To overcome this limitation, the present study proposes a comprehensive methodology for the design of compound dispersion prisms based on the first- and second-order derivative matrices of skew rays. The proposed method facilitates the analysis and design of prisms with respect to arbitrary system variables and provides an ideal basis for automatic prism design applications. Four illustrative examples are given. It is shown that the optical quantities required to evaluate the prism performance can be extracted directly from the proposed derivative matrices. In addition, it is shown in this study that the single-element 3D prism can have the same deviation angle and spectral dispersion as the 2D compound prism. PMID:27607509

  15. Optical system design of the Dyson imaging spectrometer based on the Fery prism

    NASA Astrophysics Data System (ADS)

    Pei, Linlin; Xiangli, Bin; Lv, Qunbo; Shao, Xiaopeng

    2016-07-01

    Imaging spectrometer has obtained wide development since rich feature information can be obtained by it; now, we focus on its high spectral resolution and miniaturization. In this paper, we design the Dyson imaging spectrometer system based on Fery prism. The average spectral resolution is 4.3 nm and the structure of the total length is 229 mm. It is a small, high-spectrometer imaging system. The front and rear surface of the traditional prism are plane, but the surfaces of the Fery prism are spherical, which can provide some optical power to realize imaging function and produce the dispersion effect. The Fery prism does not need to be placed in the parallel optical path, which simplifies the collimator lens and the imaging lens and are necessary in the prism spectrometer, making it possible to obtain a compact spectrometer. Full-spectrum transmittance of the prism is up to 94 %. Compared to the convex grating, the energy efficiency is greatly improved, and the free spectral range is wider, and its dispersion will not bring higher-order spectral aliasing problem. The small high spectrometer only includes two components. Its spectral range is from 400 to 1000 nm, covering the near-ultraviolet to near-infrared. The various aberrations of the typical spectrum are corrected. The spectrometer is excellent in performance.

  16. Matter Wave Deflection through a Light Prism

    NASA Astrophysics Data System (ADS)

    Ronan, Joseph; Cronin, Alexander; Holmgren, William; Hromada, Ivan; Trubko, Raisa

    2011-10-01

    In optics, it is a well-known fact that a glass prism will bend a light beam incident on its surface. We present an atom optics experiment analogous to this phenomenon, but instead we use a light prism to deflect a beam of potassium atoms. We use a Mach-Zehnder atom interferometer to precisely measure atom beam deflections of as small as 5 nm. Through studying the beam deflection, we are able to investigate the dynamic polarizability and the magic zero wavelength of potassium.

  17. PRISM, a Novel Visual Metaphor Measuring Personally Salient Appraisals, Attitudes and Decision-Making: Qualitative Evidence Synthesis

    PubMed Central

    Sensky, Tom; Büchi, Stefan

    2016-01-01

    Background PRISM (the Pictorial Representation of Illness and Self Measure) is a novel, simple visual instrument. Its utility was initially discovered serendipitously, but has been validated as a quantitative measure of suffering. Recently, new applications for different purposes, even in non-health settings, have encouraged further exploration of how PRISM works, and how it might be applied. This review will summarise the results to date from applications of PRISM and propose a generic conceptualisation of how PRISM works which is consistent with all these applications. Methods A systematic review, in the form of a qualitative evidence synthesis, was carried out of all available published data on PRISM. Results Fifty-two publications were identified, with a total of 8254 participants. Facilitated by simple instructions, PRISM has been used with patient groups in a variety of settings and cultures. As a measure of suffering, PRISM has, with few exceptions, behaved as expected according to Eric Cassell’s seminal conceptualisation of suffering. PRISM has also been used to assess beliefs about or attitudes to stressful working conditions, interpersonal relations, alcohol consumption, and suicide, amongst others. Discussion This review supports PRISM behaving as a visual metaphor of the relationship of objects (eg ‘my illness’) to a subject (eg ‘myself’) in a defined context (eg ‘my life at the moment’). As a visual metaphor, it is quick to complete and yields personally salient information. PRISM is likely to have wide applications in assessing beliefs, attitudes, and decision-making, because of its properties, and because it yields both quantitative and qualitative data. In medicine, it can serve as a generic patient-reported outcome measure. It can serve as a tool for representational guidance, can be applied to developing strategies visually, and is likely to have applications in coaching, psychological assessment and therapeutic interventions. PMID

  18. Ultradispersive adaptive prism based on a coherently prepared atomic medium

    SciTech Connect

    Sautenkov, Vladimir A.; Li Hebin; Rostovtsev, Yuri V.; Scully, Marlan O.

    2010-06-15

    We have experimentally demonstrated an ultra-dispersive optical prism made from a coherently driven Rb atomic vapor. The prism possesses spectral angular dispersion that is 6 orders of magnitude higher than that of a prism made of optical glass; such angular dispersion allows one to spatially resolve light beams with different frequencies separated by a few kilohertz. The prism operates near the resonant frequency of atomic vapor and its dispersion is optically controlled by a coherent driving field.

  19. [Development of forensic thanatology through the prism of analysis of postmortem protocols collected at the Department of Forensic Medicine, Jagiellonian University].

    PubMed

    Konopka, Tomasz

    2011-01-01

    When assessed based on the analysis of postmortem protocols, the successes of forensic thanatology appear to differ from those that might be assumed using as the foundation a review of publications and textbooks. The greatest achievements date back to as early as the 18th and 19th centuries, when the morphological changes observed in the majority of types of deaths resulting from disease-associated and traumatic causes were described. Within the past 130 years, however, or in other words, in the period when autopsy protocols were written that are today collected in the archives of the Krakow Department of Forensic Medicine, the causes and mechanisms of death became understood even when the said factors were associated with discrete postmortem changes only or no no such changes whatsoever were left. At the end of the 19th century and for a long time afterwards, a difficult problem was posed by sudden deaths, where the postmortem examinations demonstrated solely atherosclerosis and the cause of death was described as "heart palsy". As it turned out, a great portion of such deaths represented individuals with myocardial infarction; in spite of its evident macroscopic presentation, the diagnostic management of the disease was progressing very slowly. Myocardial infarction, known at least since 1912, was associated by forensic medicine with the phenomenon of sudden death only in the forties, and the ability to detect myocardial infarction in practice developed only in the fifties of the last century. The achievement of the present dissertation is the formulation of a theory ascribing such a long delay in macroscopic diagnostics of myocardial infarction to forensic medicine specialists being attached to and fond of employing the "in situ" autopsy technique, which was unfavorable from the viewpoint of heart examination, since the organ was not dissected free and removed from the body in the course of a postmortem examination. When autopsies started to concentrate on

  20. Linking magmatism with collision in an accretionary orogen

    PubMed Central

    Li, Shan; Chung, Sun-Lin; Wilde, Simon A.; Wang, Tao; Xiao, Wen-Jiao; Guo, Qian-Qian

    2016-01-01

    A compilation of U-Pb age, geochemical and isotopic data for granitoid plutons in the southern Central Asian Orogenic Belt (CAOB), enables evaluation of the interaction between magmatism and orogenesis in the context of Paleo-Asian oceanic closure and continental amalgamation. These constraints, in conjunction with other geological evidence, indicate that following consumption of the ocean, collision-related calc-alkaline granitoid and mafic magmatism occurred from 255 ± 2 Ma to 251 ± 2 Ma along the Solonker-Xar Moron suture zone. The linear or belt distribution of end-Permian magmatism is interpreted to have taken place in a setting of final orogenic contraction and weak crustal thickening, probably as a result of slab break-off. Crustal anatexis slightly post-dated the early phase of collision, producing adakite-like granitoids with some S-type granites during the Early-Middle Triassic (ca. 251–245 Ma). Between 235 and 220 Ma, the local tectonic regime switched from compression to extension, most likely caused by regional lithospheric extension and orogenic collapse. Collision-related magmatism from the southern CAOB is thus a prime example of the minor, yet tell-tale linking of magmatism with orogenic contraction and collision in an archipelago-type accretionary orogen. PMID:27167207

  1. Linking magmatism with collision in an accretionary orogen

    NASA Astrophysics Data System (ADS)

    Li, Shan; Chung, Sun-Lin; Wilde, Simon A.; Wang, Tao; Xiao, Wen-Jiao; Guo, Qian-Qian

    2016-05-01

    A compilation of U-Pb age, geochemical and isotopic data for granitoid plutons in the southern Central Asian Orogenic Belt (CAOB), enables evaluation of the interaction between magmatism and orogenesis in the context of Paleo-Asian oceanic closure and continental amalgamation. These constraints, in conjunction with other geological evidence, indicate that following consumption of the ocean, collision-related calc-alkaline granitoid and mafic magmatism occurred from 255 ± 2 Ma to 251 ± 2 Ma along the Solonker-Xar Moron suture zone. The linear or belt distribution of end-Permian magmatism is interpreted to have taken place in a setting of final orogenic contraction and weak crustal thickening, probably as a result of slab break-off. Crustal anatexis slightly post-dated the early phase of collision, producing adakite-like granitoids with some S-type granites during the Early-Middle Triassic (ca. 251–245 Ma). Between 235 and 220 Ma, the local tectonic regime switched from compression to extension, most likely caused by regional lithospheric extension and orogenic collapse. Collision-related magmatism from the southern CAOB is thus a prime example of the minor, yet tell-tale linking of magmatism with orogenic contraction and collision in an archipelago-type accretionary orogen.

  2. Linking magmatism with collision in an accretionary orogen.

    PubMed

    Li, Shan; Chung, Sun-Lin; Wilde, Simon A; Wang, Tao; Xiao, Wen-Jiao; Guo, Qian-Qian

    2016-01-01

    A compilation of U-Pb age, geochemical and isotopic data for granitoid plutons in the southern Central Asian Orogenic Belt (CAOB), enables evaluation of the interaction between magmatism and orogenesis in the context of Paleo-Asian oceanic closure and continental amalgamation. These constraints, in conjunction with other geological evidence, indicate that following consumption of the ocean, collision-related calc-alkaline granitoid and mafic magmatism occurred from 255 ± 2 Ma to 251 ± 2 Ma along the Solonker-Xar Moron suture zone. The linear or belt distribution of end-Permian magmatism is interpreted to have taken place in a setting of final orogenic contraction and weak crustal thickening, probably as a result of slab break-off. Crustal anatexis slightly post-dated the early phase of collision, producing adakite-like granitoids with some S-type granites during the Early-Middle Triassic (ca. 251-245 Ma). Between 235 and 220 Ma, the local tectonic regime switched from compression to extension, most likely caused by regional lithospheric extension and orogenic collapse. Collision-related magmatism from the southern CAOB is thus a prime example of the minor, yet tell-tale linking of magmatism with orogenic contraction and collision in an archipelago-type accretionary orogen. PMID:27167207

  3. 21 CFR 886.5810 - Ophthalmic prism reader.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic prism reader. 886.5810 Section 886.5810...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5810 Ophthalmic prism reader. (a) Identification. An ophthalmic prism reader is a device intended for use by a patient who is in a supine...

  4. 21 CFR 886.5810 - Ophthalmic prism reader.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic prism reader. 886.5810 Section 886.5810...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5810 Ophthalmic prism reader. (a) Identification. An ophthalmic prism reader is a device intended for use by a patient who is in a supine...

  5. 21 CFR 886.1665 - Ophthalmic rotary prism.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic rotary prism. 886.1665 Section 886.1665...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1665 Ophthalmic rotary prism. (a) Identification. An ophthalmic rotary prism is a device with various prismatic powers intended to be handheld...

  6. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1655 Ophthalmic Fresnel prism. (a) Identification. An ophthalmic Fresnel prism is a device that is a thin plastic sheet with embossed rulings...

  7. 21 CFR 886.1665 - Ophthalmic rotary prism.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic rotary prism. 886.1665 Section 886.1665...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1665 Ophthalmic rotary prism. (a) Identification. An ophthalmic rotary prism is a device with various prismatic powers intended to be handheld...

  8. 21 CFR 886.1665 - Ophthalmic rotary prism.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Ophthalmic rotary prism. 886.1665 Section 886.1665...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1665 Ophthalmic rotary prism. (a) Identification. An ophthalmic rotary prism is a device with various prismatic powers intended to be handheld...

  9. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1655 Ophthalmic Fresnel prism. (a) Identification. An ophthalmic Fresnel prism is a device that is a thin plastic sheet with embossed rulings...

  10. 21 CFR 886.1665 - Ophthalmic rotary prism.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic rotary prism. 886.1665 Section 886.1665...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1665 Ophthalmic rotary prism. (a) Identification. An ophthalmic rotary prism is a device with various prismatic powers intended to be handheld...

  11. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1655 Ophthalmic Fresnel prism. (a) Identification. An ophthalmic Fresnel prism is a device that is a thin plastic sheet with embossed rulings...

  12. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1655 Ophthalmic Fresnel prism. (a) Identification. An ophthalmic Fresnel prism is a device that is a thin plastic sheet with embossed rulings...

  13. 21 CFR 886.1655 - Ophthalmic Fresnel prism.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ophthalmic Fresnel prism. 886.1655 Section 886...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1655 Ophthalmic Fresnel prism. (a) Identification. An ophthalmic Fresnel prism is a device that is a thin plastic sheet with embossed rulings...

  14. 21 CFR 886.1665 - Ophthalmic rotary prism.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic rotary prism. 886.1665 Section 886.1665...) MEDICAL DEVICES OPHTHALMIC DEVICES Diagnostic Devices § 886.1665 Ophthalmic rotary prism. (a) Identification. An ophthalmic rotary prism is a device with various prismatic powers intended to be handheld...

  15. Symmetry Breaking Analysis of Prism Adaptation's Latent Aftereffect

    ERIC Educational Resources Information Center

    Frank, Till D.; Blau, Julia J. C.; Turvey, Michael T.

    2012-01-01

    The effect of prism adaptation on movement is typically reduced when the movement at test (prisms off) differs on some dimension from the movement at training (prisms on). Some adaptation is latent, however, and only revealed through further testing in which the movement at training is fully reinstated. Applying a nonlinear attractor dynamic model…

  16. 21 CFR 886.5810 - Ophthalmic prism reader.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ophthalmic prism reader. 886.5810 Section 886.5810...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5810 Ophthalmic prism reader. (a) Identification. An ophthalmic prism reader is a device intended for use by a patient who is in a supine...

  17. 21 CFR 886.5810 - Ophthalmic prism reader.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Ophthalmic prism reader. 886.5810 Section 886.5810...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5810 Ophthalmic prism reader. (a) Identification. An ophthalmic prism reader is a device intended for use by a patient who is in a supine...

  18. 21 CFR 886.5810 - Ophthalmic prism reader.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Ophthalmic prism reader. 886.5810 Section 886.5810...) MEDICAL DEVICES OPHTHALMIC DEVICES Therapeutic Devices § 886.5810 Ophthalmic prism reader. (a) Identification. An ophthalmic prism reader is a device intended for use by a patient who is in a supine...

  19. Magnetic prism alignment system for measuring large-angle strabismus.

    PubMed

    Bishop, John Edward

    2014-02-01

    Prismatic measurement of large-angle strabismus requires the simultaneous use of two or more prisms for neutralization. To facilitate the clinical measurement of large-angle strabismus a new prism system was designed utilizing a flat plate and a ferrous metal surface coupled with prisms containing rare earth magnets implanted in their base and bottom surfaces. PMID:24569000

  20. Dual-prism interferometer for collimation testing

    SciTech Connect

    Hii, King Ung; Kwek, Kuan Hiang

    2009-01-10

    An air-wedge lateral-shear interferometer using two prisms is presented. With a variable shear, the interferometer is suitable for testing collimation of a wide range of beam sizes down to a few millimeters in diameter. No antireflection coatings are necessary. Collimation for a light source with short coherent length is also demonstrated.

  1. Comparing Volumes of Prisms and Pyramids

    ERIC Educational Resources Information Center

    Vinogradova, Natalya

    2012-01-01

    Students' experience in using formulas for volumes is often limited to substituting numbers into given formulas. An activity presented in this article may help students make connections between the formulas for volumes of prisms and volumes of pyramids. In addition, some interesting facts from number theory arise, demonstrating strong connections…

  2. Prisms Throw Light on Developmental Disorders

    ERIC Educational Resources Information Center

    Brookes, Rebecca L.; Nicolson, Roderick I.; Fawcett, Angela J.

    2007-01-01

    Prism adaptation, in which the participant adapts to prismatic glasses that deflect vision laterally, is a specific test of cerebellar function. Fourteen dyslexic children (mean age 13.5 years); 14 children with developmental coordination disorder (DCD): 6 of whom had comorbid dyslexia; and 12 control children matched for age and IQ underwent…

  3. Comparing the Volumes of Rectangular Prisms

    ERIC Educational Resources Information Center

    Assuah, Charles K.; Wiest, Lynda R.

    2010-01-01

    Can middle-grades students determine which of two rectangular prisms has a larger volume? Can they do so without using a formula? Geometry, and particularly the concept of volume, is important in many subjects, such as physics and chemistry. Students greatly enhance their mathematics knowledge when they make generalizations and construct arguments…

  4. Reflecting Schmidt/Littrow Prism Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.; Page, N. A.; Shack, R. V.; Shannon, R. R.

    1985-01-01

    High resolution achieved with wide field of view. Imaging Spectrometer features off-axis reflecting optics, including reflecting "slit" that also serves as field flattener. Only refracting element is prism. By scanning slit across object or scene and timing out signal, both spectral and spatial information in scene are obtained.

  5. Optical vortices generation using the Wollaston prism

    SciTech Connect

    Kurzynowski, Piotr; Wozniak, Wladyslaw A.; Fraczek, Ewa

    2006-10-20

    A new setup of interferometers is proposed in which the set of specific optical markers - optical vortices - could be generated. The classical Mach-Zender two-beam interferometer has been modernized using the Wollaston prism. In this setup, the optical vortices could be obtained for a wide range of both beam parameters. The numerical analysis and experiments confirm our theoretical predictions.

  6. Formation of forearc basins by collision between seamounts and accretionary wedges: an example from the New Hebrides subduction zone

    USGS Publications Warehouse

    Collot, J.-Y.; Fisher, M.A.

    1989-01-01

    Seabeam data reveal two deep subcircular reentrants in the lower arc slope of the New Hebrides island arc that may illustrate two stages in the development of a novel type of forearc basin. The Malekula reentrant lies just south of the partly subducted Bougainville seamount. This proximity, as well as the similarity in morphology between the reentrant and an indentation in the lower arc slope off Japan, suggests that the Malekula reentrant formed by the collision of a seamount with the arc. An arcuate fold-thrust belt has formed across the mouth of the reentrant, forming the toe of a new accretionary wedge. The Efate reentrant may show the next stage in basin development. This reentrant lies landward of a lower-slope ridge that may have begun to form as an arcuate fold-thrust belt across the mouth of a reentrant. This belt may have grown by continued accretion at the toe of the wedge, by underplating beneath the reentrant, and by trapping of sediment shed from the island arc. These processes could result in a roughly circular forearc basin. Basins that may have formed by seamount collision lie within the accretionary wedge adjacent to the Aleutian trenches. -Authors

  7. Boolean Operations with Prism Algebraic Patches.

    PubMed

    Bajaj, Chandrajit; Paoluzzi, Alberto; Portuesi, Simone; Lei, Na; Zhao, Wenqi

    2008-01-01

    In this paper we discuss a symbolic-numeric algorithm for Boolean operations, closed in the algebra of curved polyhedra whose boundary is triangulated with algebraic patches (A-patches). This approach uses a linear polyhedron as a first approximation of both the arguments and the result. On each triangle of a boundary representation of such linear approximation, a piecewise cubic algebraic interpolant is built, using a C(1)-continuous prism algebraic patch (prism A-patch) that interpolates the three triangle vertices, with given normal vectors. The boundary representation only stores the vertices of the initial triangulation and their external vertex normals. In order to represent also flat and/or sharp local features, the corresponding normal-per-face and/or normal-per-edge may be also given, respectively. The topology is described by storing, for each curved triangle, the two triples of pointers to incident vertices and to adjacent triangles. For each triangle, a scaffolding prism is built, produced by its extreme vertices and normals, which provides a containment volume for the curved interpolating A-patch. When looking for the result of a regularized Boolean operation, the 0-set of a tri-variate polynomial within each such prism is generated, and intersected with the analogous 0-sets of the other curved polyhedron, when two prisms have non-empty intersection. The intersection curves of the boundaries are traced and used to decompose each boundary into the 3 standard classes of subpatches, denoted in, out and on. While tracing the intersection curves, the locally refined triangulation of intersecting patches is produced, and added to the boundary representation. PMID:21516262

  8. Polyphase deformation of a Paleozoic metamorphosed subduction-accretionary complex in Beishan Orogen, southern Altaids

    NASA Astrophysics Data System (ADS)

    Song, Dongfang; Xiao, Wenjiao

    2014-05-01

    The Lebaquan Complex in central Beishan plays a significant role in understanding the subduction-accretion-collision processes of the Beishan orogenic collage, southern Altaids. This complex is a polyphase deformed upper greenschist to lower amphibolite facies metamorphic rock assemblages composed of metasedimentary sequence, gneissic plutons, metacherts, amphibolites and marbles, with multiple generations of syn-tectonic leucogranite-pegmatite and post-tectonic mafic dykes. Lithologic and geochemical characteristics show the Lebaquan Complex is a forearc-arc complex. Four stages of deformation can be recognized for the Lebaquan Complex. The D1 deformation is defined by pervasively developed foliations (S1) defined by alternative metamorphic layering and intrafolia isoclinal folds of quartz veins (F1). The D2 deformation is indicated by crenulation cleavage (S2) mainly developed in the schists, extensively-developed tight to open folds and asymmetric folds (F2) and pinch and swell structures. The D3 deformation is characterized by high-strain ductile shearing, which modified earlier structures. Small-scale asymmetric folds, σ-type porphyroclasts and S-C fabrics indicate dextral sense of shearing in east-west direction. The D4 deformation is represented by ductile to brittle structures including open/gentle folds, kink folds and small scale thrust faults which overprint earlier deformations. The overall deformation of this complex indicates a geodynamic setting change from initial north-south directed strong compression to later east-west directed transpression and finally extension. LA-ICP-MS zircon U-Pb dating was performed on key lithologies. Youngest age peak of detrital zircons from a garnet-mica-quartz schist is ~424 Ma, constraining the depositional age for the protolith of the metasedimentary sequence. A syn-deformation leucogranitic dyke that underwent D2 but did not experience D1 and a post-deformation mafic dyke that intrudes all the lithologies were

  9. Self-referenced prism deflection measurement schemes with microradian precision

    SciTech Connect

    Olson, Rebecca; Paul, Justin; Bergeson, Scott; Durfee, Dallin S

    2005-08-01

    We have demonstrated several inexpensive methods that can be used to measure the deflection angles of prisms with microradian precision. The methods are self-referenced, where various reversals are used to achieve absolute measurements without the need of a reference prism or any expensive precision components other than the prisms under test. These techniques are based on laser interferometry and have been used in our laboratory to characterize parallel-plate beam splitters, penta prisms, right-angle prisms, and corner cube reflectors using only components typically available in an optics laboratory.

  10. Linking collisional and accretionary orogens during Rodinia assembly and breakup: Implications for models of supercontinent cycles

    NASA Astrophysics Data System (ADS)

    Cawood, Peter A.; Strachan, Robin A.; Pisarevsky, Sergei A.; Gladkochub, Dmitry P.; Murphy, J. Brendan

    2016-09-01

    Periodic assembly and dispersal of continental fragments has been a characteristic of the solid Earth for much of its history. Geodynamic drivers of this cyclic activity are inferred to be either top-down processes related to near surface lithospheric stresses at plate boundaries or bottom-up processes related to mantle convection and, in particular, mantle plumes, or some combination of the two. Analysis of the geological history of Rodinian crustal blocks suggests that internal rifting and breakup of the supercontinent were linked to the initiation of subduction and development of accretionary orogens around its periphery. Thus, breakup was a top-down instigated process. The locus of convergence was initially around north-eastern and northern Laurentia in the early Neoproterozoic before extending to outboard of Amazonia and Africa, including Avalonia-Cadomia, and arcs outboard of Siberia and eastern to northern Baltica in the mid-Neoproterozoic (∼760 Ma). The duration of subduction around the periphery of Rodinia coincides with the interval of lithospheric extension within the supercontinent, including the opening of the proto-Pacific at ca. 760 Ma and the commencement of rifting in east Laurentia. Final development of passive margin successions around Laurentia, Baltica and Siberia was not completed until the late Neoproterozoic to early Paleozoic (ca. 570-530 Ma), which corresponds with the termination of convergent plate interactions that gave rise to Gondwana and the consequent relocation of subduction zones to the periphery of this supercontinent. The temporal link between external subduction and internal extension suggests that breakup was initiated by a top-down process driven by accretionary tectonics along the periphery of the supercontinent. Plume-related magmatism may be present at specific times and in specific places during breakup but is not the prime driving force. Comparison of the Rodinia record of continental assembly and dispersal with that

  11. The PRISM palaeoclimate reconstruction and Pliocene sea-surface temperature

    USGS Publications Warehouse

    Dowsett, H.J.

    2007-01-01

    In this paper, I present a summary of the Pliocene Research, Interpretation and Synoptic Mapping (PRISM) palaeoenvironmental reconstruction, with emphasis on its historical development and range of boundary condition datasets. Sea-surface temperature (SST), sea level, sea ice, land cover (vegetation and ice) and topography are discussed as well as many of the assumptions required to create an integrated global-scale reconstruction. New multiproxy research shows good general agreement on the magnitude of mid-Pliocene SST warming. Future directions, including maximum and minimum SST analyses and deep ocean temperature estimates aimed at a full three-dimensional reconstruction, are presented. ?? The Micropalaeontological Society 2007.

  12. Propagation tectonics and multiple accretionary processes of the Qinling Orogen

    NASA Astrophysics Data System (ADS)

    Dong, Yunpeng; Zhang, Xiaoning; Liu, Xiaoming; Li, Wei; Chen, Qing; Zhang, Guowei; Zhang, Hongfu; Yang, Zhao; Sun, Shengsi; Zhang, Feifei

    2015-05-01

    The Qinling Orogen was built through collision between the North China and South China Blocks. Previous detailed geological, geochemical and geochronological investigations revealed that the mountain range can be divided into four tectonic units with distinct tectono-lithostratigraphy, which are, from north to south, the southern sector of the North China Block, North Qinling Belt, South Qinling Belt and northern sector of the South China Block, separated by the Kuanping, Shangdan and Mianlue sutures. According to the petrology, geochemistry and geochronology of ophiolitic mélanges and related magmatic rocks, as well as the features of sedimentary units, we think that the North China Block, the North Qinling Belt and the South China Block were originally independent continental units while the South Qinling Belt had been the northern part of the South China Block. These units experienced three episodes of accretionary tectonic processes and amalgamation from south to north. The Neoproterozoic accretion took place along the Luonan-Luanchuan Fault and Kuanping ophiolitic mélange belt as a result of southward subduction and subsequent collision between the North Qinling and North China Blocks during ca. 1.0-0.8 Ga related to the formation of the supercontinent of Rodinia. The Paleozoic accretion occurred along the Shangdan suture resulted from northward subduction of oceanic lithosphere in the Early Paleozoic and subsequent continental subduction in the Late Paleozoic. Late Triassic accretion took place along the Mianlue suture between the South Qinling and South China Blocks due to northward subduction of the Mianlue oceanic lithosphere during the Permian-Early Triassic and subsequent collision in the Late Triassic. After the Late Triassic collision along the Mianlue suture the whole Qinling Mountain range entered the phase of intense intracontinental deformation.

  13. The Palaeoproterozoic crustal evolution: evidences from granulite-gneiss belts, collisional and accretionary orogens

    NASA Astrophysics Data System (ADS)

    Mints, M. V.; Konilov, A. N.

    2003-04-01

    The Palaeoproterozoic juvenile assemblages were emplaced within two types of mobile belts: (1) high-grade or "granulite-gneiss" belts; (2) low- and medium-grade volcano-sedimentary and volcano-plutonic belts. Type (1) belts resulted from plume-induced heating, magmatism, emergence of riftogenic basins and volcano-tectonic depressions, their filling with rift-type sediments and juvenile but strongly contaminated lavas and ash-flow deposits, high-grade recrystallization of the lower- and mid-crustal assemblages including the filling of the basins and depressions that followed in intraplate and back-arc settings, and final thrusting and exhumation caused by collision-related tectonism. Type (2) belts represent sutures containing MORB- and arc-related assemblages, together with initial rift-related assemblages formed during evolution of the short-lived, mainly Red Sea-type oceans (intracontinental collisional orogens) and systems of oceanic, island-arc and back-arc terranes amalgamated along continent margins (peripheral accretionary orogens). Palaeoproterozoic history can be subdivided into five periods: (1) 2.51-2.44 Ga superplume activity and displacement of Fennoscandia; (2) 2.44-2.0 (2.11) Ga quiescent within-plate development complicated by local plume- and plate tectonics-related processes; (3) a 2.0-1.95 Ga superplume event; (4) 1.95-1.75 (1.71) Ga combined plume- and plate tectonics-related evolution, resulting in the partial disruption of the continental crust, and formation of accretionary orogens along some margins of the supercontinent and rebirth of the supercontinent entity, and (5) < 1,75 Ga post- and anorogenic magmatism and metamorphism. Magmatic and thermal activity during the early Palaeoproterozoic was almost exclusively concentrated within Laurentia (comprising North American and Fennoscandian cratons). In contrast, late Palaeoproterozoic assemblages are distributed within all continents. The simultaneous appearance of within-plate plume

  14. Effects of Prism Eyeglasses on Objective and Subjective Fixation Disparity

    PubMed Central

    Schroth, Volkhard; Joos, Roland; Jaschinski, Wolfgang

    2015-01-01

    In optometry of binocular vision, the question may arise whether prisms should be included in eyeglasses to compensate an oculomotor and/or sensory imbalance between the two eyes. The corresponding measures of objective and subjective fixation disparity may be reduced by the prisms, or the adaptability of the binocular vergence system may diminish effects of the prisms over time. This study investigates effects of wearing prisms constantly for about 5 weeks in daily life. Two groups of 12 participants received eyeglasses with prisms having either a base-in direction or a base-out direction with an amount up to 8 prism diopters. Prisms were prescribed based on clinical fixation disparity test plates at 6 m. Two dependent variables were used: (1) subjective fixation disparity was indicated by a perceived offset of dichoptic nonius lines that were superimposed on the fusion stimuli and (2) objective fixation disparity was measured with a video based eye tracker relative to monocular calibration. Stimuli were presented at 6 m and included either central or more peripheral fusion stimuli. Repeated measurements were made without the prisms and with the prisms after about 5 weeks of wearing these prisms. Objective and subjective fixation disparity were correlated, but the type of fusion stimulus and the direction of the required prism may play a role. The prisms did not reduce the fixation disparity to zero, but induced significant changes in fixation disparity with large effect sizes. Participants receiving base-out prisms showed hypothesized effects, which were concurrent in both types of fixation disparity. In participants receiving base-in prisms, the individual effects of subjective and objective effects were negatively correlated: the larger the subjective (sensory) effect, the smaller the objective (motor) effect. This response pattern was related to the vergence adaptability, i.e. the individual fusional vergence reserves. PMID:26431525

  15. Effects of Prism Eyeglasses on Objective and Subjective Fixation Disparity.

    PubMed

    Schroth, Volkhard; Joos, Roland; Jaschinski, Wolfgang

    2015-01-01

    In optometry of binocular vision, the question may arise whether prisms should be included in eyeglasses to compensate an oculomotor and/or sensory imbalance between the two eyes. The corresponding measures of objective and subjective fixation disparity may be reduced by the prisms, or the adaptability of the binocular vergence system may diminish effects of the prisms over time. This study investigates effects of wearing prisms constantly for about 5 weeks in daily life. Two groups of 12 participants received eyeglasses with prisms having either a base-in direction or a base-out direction with an amount up to 8 prism diopters. Prisms were prescribed based on clinical fixation disparity test plates at 6 m. Two dependent variables were used: (1) subjective fixation disparity was indicated by a perceived offset of dichoptic nonius lines that were superimposed on the fusion stimuli and (2) objective fixation disparity was measured with a video based eye tracker relative to monocular calibration. Stimuli were presented at 6 m and included either central or more peripheral fusion stimuli. Repeated measurements were made without the prisms and with the prisms after about 5 weeks of wearing these prisms. Objective and subjective fixation disparity were correlated, but the type of fusion stimulus and the direction of the required prism may play a role. The prisms did not reduce the fixation disparity to zero, but induced significant changes in fixation disparity with large effect sizes. Participants receiving base-out prisms showed hypothesized effects, which were concurrent in both types of fixation disparity. In participants receiving base-in prisms, the individual effects of subjective and objective effects were negatively correlated: the larger the subjective (sensory) effect, the smaller the objective (motor) effect. This response pattern was related to the vergence adaptability, i.e. the individual fusional vergence reserves. PMID:26431525

  16. Beyond the Sensorimotor Plasticity: Cognitive Expansion of Prism Adaptation in Healthy Individuals

    PubMed Central

    Michel, Carine

    2016-01-01

    Sensorimotor plasticity allows us to maintain an efficient motor behavior in reaction to environmental changes. One of the classical models for the study of sensorimotor plasticity is prism adaptation. It consists of pointing to visual targets while wearing prismatic lenses that shift the visual field laterally. The conditions of the development of the plasticity and the sensorimotor after-effects have been extensively studied for more than a century. However, the interest taken in this phenomenon was considerably increased since the demonstration of neglect rehabilitation following prism adaptation by Rossetti et al. (1998). Mirror effects, i.e., simulation of neglect in healthy individuals, were observed for the first time by Colent et al. (2000). The present review focuses on the expansion of prism adaptation to cognitive functions in healthy individuals during the last 15 years. Cognitive after-effects have been shown in numerous tasks even in those that are not intrinsically spatial in nature. Altogether, these results suggest the existence of a strong link between low-level sensorimotor plasticity and high-level cognitive functions and raise important questions about the mechanisms involved in producing unexpected cognitive effects following prism adaptation. Implications for the functional mechanisms and neuroanatomical network of prism adaptation are discussed to explain how sensorimotor plasticity may affect cognitive processes. PMID:26779088

  17. DSM Generation from ALSO/PRISM Images Using SAT-PP

    NASA Astrophysics Data System (ADS)

    Wolff, Kirsten; Gruen, Armin

    2008-11-01

    One of the most important products of ALOS/PRISM image data are accurate DSMs. To exploit the full potential of the full resolution of PRISM for DSM generation, a highly developed image matcher is needed. As a member of the validation and calibration team for PRISM we published earlier results of DSM generation using PRISM image triplets in combination with our software package SAT-PP. The overall accuracy across all object and image features for all tests lies between 1-5 pixels in matching, depending primarily on surface roughness, vegetation, image texture and image quality. Here we will discuss some new results. We focus on four different topics: the use of two different evaluation methods, the difference between a 5m and a 10m GSD for the final PRISM DSM, the influence of the level of initial information and the comparison of the quality of different combinations of the three different views forward, nadir and backward. All tests have been conducted with our testfield Bern/Thun, Switzerland.

  18. PRISM3 DOT1 Atlantic Basin Reconstruction

    USGS Publications Warehouse

    Dowsett, Harry; Robinson, Marci; Dwyer, Gary; Chandler, Mark; Cronin, Thomas

    2006-01-01

    PRISM3 DOT1 (Pliocene Research, Interpretation and Synoptic Mapping 3, Deep Ocean Temperature 1) provides a three-dimensional temperature reconstruction for the mid-Pliocene Atlantic basin, the first of several regional data sets that will comprise a global mid-Pliocene reconstruction. DOT1 is an alteration of modern temperature values for the Atlantic Ocean in 4 degree x 5 degree cells in 13 depth layers for December 1 based on Mg/Ca-derived BWT estimates from seventeen DSDP and ODP Sites and SST estimates from the PRISM2 reconstruction (Dowsett et al., 1999). DOT1 reflects a vaguely modern circulation system, assuming similar processes of deep-water formation; however, North Atlantic Deep Water (NADW) production is increased, and Antarctic Bottom Water (AABW) production is decreased. Pliocene NADW was approximately 2 degreesC warmer than modern temperatures, and Pliocene AABW was approximately 0.3 degreesC warmer than modern temperatures.

  19. Overland Tidal Power Generation Using Modular Tidal Prism

    SciTech Connect

    Khangaonkar, Tarang; Yang, Zhaoqing; Geerlofs, Simon H.; Copping, Andrea

    2010-03-01

    Naturally occurring sites with sufficient kinetic energy suitable for tidal power generation with sustained currents > 1 to 2 m/s are relatively rare. Yet sites with greater than 3 to 4 m of tidal range are relatively common around the U.S. coastline. Tidal potential does exist along the shoreline but is mostly distributed, and requires an approach which allows trapping and collection to also be conducted in a distributed manner. In this paper we examine the feasibility of generating sustainable tidal power using multiple nearshore tidal energy collection units and present the Modular Tidal Prism (MTP) basin concept. The proposed approach utilizes available tidal potential by conversion into tidal kinetic energy through cyclic expansion and drainage from shallow modular manufactured overland tidal prisms. A preliminary design and configuration of the modular tidal prism basin including inlet channel configuration and basin dimensions was developed. The unique design was shown to sustain momentum in the penstocks during flooding as well as ebbing tidal cycles. The unstructured-grid finite volume coastal ocean model (FVCOM) was used to subject the proposed design to a number of sensitivity tests and to optimize the size, shape and configuration of MTP basin for peak power generation capacity. The results show that an artificial modular basin with a reasonable footprint (≈ 300 acres) has the potential to generate 10 to 20 kw average energy through the operation of a small turbine located near the basin outlet. The potential of generating a total of 500 kw to 1 MW of power through a 20 to 40 MTP basin tidal power farms distributed along the coastline of Puget Sound, Washington, is explored.

  20. Rotationally shearing interferometer employing modified Dove prisms

    NASA Astrophysics Data System (ADS)

    Paez, Gonzalo; Strojnik, Marija; Moreno, Ivan

    2003-12-01

    We describe the rotationally shearing interferometer (RSI) employing modified Dove prisms, designed with a widened aperture to increase throughput and with larger base angles to minimize the wave-front tilt introduced due to manufacturing errors. Experimental results obtained with the RSI ascertain the feasibility of the design. This work demonstrates that the rotationally shearing interferometry may be used to perform some functions of the traditional astronomical instruments.

  1. Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex.

    PubMed

    Dielforder, Armin; Vollstaedt, Hauke; Vennemann, Torsten; Berger, Alfons; Herwegh, Marco

    2015-01-01

    Seismological data from recent subduction earthquakes suggest that megathrust earthquakes induce transient stress changes in the upper plate that shift accretionary wedges into an unstable state. These stress changes have, however, never been linked to geological structures preserved in fossil accretionary complexes. The importance of coseismically induced wedge failure has therefore remained largely elusive. Here we show that brittle faulting and vein formation in the palaeo-accretionary complex of the European Alps record stress changes generated by subduction-related earthquakes. Early veins formed at shallow levels by bedding-parallel shear during coseismic compression of the outer wedge. In contrast, subsequent vein formation occurred by normal faulting and extensional fracturing at deeper levels in response to coseismic extension of the inner wedge. Our study demonstrates how mineral veins can be used to reveal the dynamics of outer and inner wedges, which respond in opposite ways to megathrust earthquakes by compressional and extensional faulting, respectively. PMID:26105966

  2. Linking megathrust earthquakes to brittle deformation in a fossil accretionary complex

    PubMed Central

    Dielforder, Armin; Vollstaedt, Hauke; Vennemann, Torsten; Berger, Alfons; Herwegh, Marco

    2015-01-01

    Seismological data from recent subduction earthquakes suggest that megathrust earthquakes induce transient stress changes in the upper plate that shift accretionary wedges into an unstable state. These stress changes have, however, never been linked to geological structures preserved in fossil accretionary complexes. The importance of coseismically induced wedge failure has therefore remained largely elusive. Here we show that brittle faulting and vein formation in the palaeo-accretionary complex of the European Alps record stress changes generated by subduction-related earthquakes. Early veins formed at shallow levels by bedding-parallel shear during coseismic compression of the outer wedge. In contrast, subsequent vein formation occurred by normal faulting and extensional fracturing at deeper levels in response to coseismic extension of the inner wedge. Our study demonstrates how mineral veins can be used to reveal the dynamics of outer and inner wedges, which respond in opposite ways to megathrust earthquakes by compressional and extensional faulting, respectively. PMID:26105966

  3. Tidal Prism Modeling of Phytoplankton and Nitrogen Concentrations in Narragansett Bay and its Sub-Embayments

    EPA Science Inventory

    A tidal prism model was developed to calculate temporal changes in the spatially averaged concentration of three state variables: phytoplankton, dissolved inorganic nitrogen, and detritus. Our main objective was to develop a model to help us understand the causes of phytoplankton...

  4. Compound prism design principles, III: linear-in-wavenumber and optical coherence tomography prisms

    PubMed Central

    Hagen, Nathan; Tkaczyk, Tomasz S.

    2011-01-01

    We extend the work of the first two papers in this series [Appl. Opt. 50, 4998–5011 (2011), Appl. Opt. 50, 5012–5022 (2011)] to design compound prisms for linear-in-wavenumber dispersion, especially for application in spectral domain optical coherence tomography (OCT). These dispersive prism designs are believed to be the first to meet the requirements of high resolution OCT systems in direct-view geometry, where they can be used to shrink system size, to improve light throughput, to reduce stray light, and to reduce errors resulting from interpolating between wavelength- and wavenumber-sampled domains. We show prism designs that can be used for thermal sources or for wideband superluminescent diodes centered around wavelengths 850, 900, 1300, and 1375 nm. PMID:22423147

  5. Slow and delayed deformation and uplift of the outermost subduction prism following ETS and seismogenic slip events beneath Nicoya Peninsula, Costa Rica

    NASA Astrophysics Data System (ADS)

    Davis, Earl E.; Villinger, Heinrich; Sun, Tianhaozhe

    2015-01-01

    Two ODP CORK (Ocean Drilling Program circulation obviation retrofit kit) borehole hydrologic observatory sites deployed in 2002 at the toe of the subduction prism off Nicoya Peninsula, Costa Rica were visited in December 2013. The five years of seafloor and formation fluid pressure data collected since the previous visit include clear signals associated with an episodic tremor and slip (ETS) event off the coast of Nicoya Peninsula in 2009, and a Mw 7.6 subduction thrust earthquake beneath the Peninsula in 2012. Formation pressure anomalies associated with the ETS event are similar to ones observed following ETS events observed previously here, as well as ones following very low frequency earthquake swarms within the Nankai accretionary prism off southwestern Japan. Positive and negative impulsive transients in the hanging wall and foot wall of the subduction thrust, respectively, suggest contractional and dilatational strain generated by local slip propagating up the thrust fault beneath the outermost prism. In the case of the 2009 event, the transients occurred roughly two weeks after the initiation of slip observed at GPS sites along the adjacent coast. At the same time, a decrease in seafloor pressure at the prism site relative to the subducting plate was observed, indicating concurrent uplift of the prism of 1.2 cm. Other events at the prism toe following ETS events closer to the coast are seen in 2006, 2007, 2008, 2010, and 2011. The time between the initiation of ETS slip constrained by GPS and the onset of the prism toe transients suggest up-dip “rupture” propagation along the seaward part of the subduction thrust at rates of a few km/day. In the case of the 2009 event, the slip at the prism toe (c. 11 cm), estimated from the 1.2 cm uplift and the local dip on the decollement (6°), is roughly a factor of 5 greater than the slip further landward estimated from GPS data by Dixon et al. (in press). In other cases, slip at the toe is less or unresolvable

  6. Incrementally developed slickenfibers — Geological record of repeating low stress-drop seismic events?

    NASA Astrophysics Data System (ADS)

    Fagereng, Åke; Remitti, Francesca; Sibson, Richard H.

    2011-10-01

    An accretionary mélange of Triassic age ocean floor sediments exposed in the Chrystalls Beach Complex, South Island, New Zealand, comprises competent sandstone and chert phacoids set in a cleaved mudstone matrix, deformed in a continuous-discontinuous style at subgreenschist conditions. Deformation structures include a pervasive anastomosing fault-fracture mesh of multiple shearing surfaces, subparallel to cleavage, coated with incrementally developed quartz-calcite slickenfibers. Microstructural observations reveal slickenfiber growth by 'crack-seal' shear slip increments of 10-100 μm, with incremental slip transfer of the same order accommodated by opening of extension fractures that link en echelon slip surfaces. Individual slip surfaces can be traced for meters to tens of meters so that the ratio of average slip, u, to potential rupture length, L, predominantly lies within the range, 10 - 6 < u/ L < 10 - 5 , characteristic of microearthquakes obeying 'constant stress-drop' scaling with a low stress-drop Δτ ~ 30 kPa, typical of low frequency earthquakes. The host-rock assemblage, metamorphic environment, inference of near-lithostatic fluid overpressures, low stress-drop and mixed continuous-discontinuous shearing, resemble conditions and characteristics of low frequency earthquakes as identified within the seismic signals recorded during episodic tremor and slow slip events, at the downdip end of the seismogenic subduction thrust interface and within accretionary prisms.

  7. Design of an Airborne Portable Remote Imaging Spectrometer (PRISM) for the Coastal Ocean

    NASA Technical Reports Server (NTRS)

    Mouroulis, P.; vanGorp, B.; Green, R. O.; Cohen, D.; Wilson, D.; Randall, D.; Rodriguez, J.; Polanco, O.; Dierssen, H.; Balasubramanian, K.; Vargas, R.; Hein, R.; Sobel, H.; Eastwood, M.

    2010-01-01

    PRISM is a pushbroom imaging spectrometer currently under development at the Jet Propulsion Laboratory, intended to address the needs of airborne coastal ocean science research. We describe here the instrument design and the technologies that enable it to achieve its distinguishing characteristics. PRISM covers the 350-1050 nm range with a 3.1 nm sampling and a 33(deg) field of view. The design provides for high signal to noise ratio, high uniformity of response, and low polarization sensitivity. The complete instrument also incorporates two additional wavelength bands at 1240 and 1610 nm in a spot radiometer configuration to aid with atmospheric correction.

  8. Cavity Enhanced Absorption Spectroscopy using a Prism Cavity and Supercontinuum Source

    NASA Astrophysics Data System (ADS)

    Lehmann, Kevin K.; Johnston, Paul S.

    2010-03-01

    The multiplex advantage of current cavity enhanced spectrometers is limited by the limited high reflectivity bandwidth of the dielectric mirrors used to construct the high finesse cavity. We report on our development of a spectrometer that uses Brewster's angle retroreflectors that is excited with supercontinuum radiation generated by a 1.06 μm pumped photonic crystal fiber, which covers the 500-1800 nm spectral range. Recent progress will be discussed including modeling of the prism cavity losses, alternative prism materials for use in the UV and mid-IR, and a new higher power source pumped by a mode-locked laser.

  9. Some experiments with thin prisms

    NASA Astrophysics Data System (ADS)

    Fernando, P. C. B.

    1980-11-01

    In most attempts at modernizing the college physics curriculum one of the first branches of physics to be eliminated is geometrical optics. However, in developing countries where the curriculum must give emphasis to applied areas (if physics is to survive at all!), geometrical optics has a role to play, especially in its relationship to the professional course ''Optometry.'' The author presents a few experiments in geometrical optics with an ophthalmic opitics bias, which could be introduced into the college physics laboratory.

  10. Tectonostratigraphy and provenance of an accretionary complex within the Yarlung-Zangpo suture zone, southern Tibet: Insights into subduction-accretion processes in the Neo-Tethys

    NASA Astrophysics Data System (ADS)

    Cai, Fulong; Ding, Lin; Leary, Ryan J.; Wang, Houqi; Xu, Qiang; Zhang, Liyun; Yue, Yahui

    2012-10-01

    Accretionary complexes record critical information about the history of subduction and accretion along the southern margin of Asia prior to the India-Asia collision. This paper presents detailed field mapping, petrographic and detrital zircon U-Pb data from an accretionary complex within the Yalung-Zangpo suture zone, southern Tibet. From structurally higher to lower levels, the accretionary complex consists of a serpentinite mélange, the chert-matrix Tangga mélange, the mud-matrix Pomunong mélange, and the coherent Rongmawa Formation. The Tangga mélange consists of Late Triassic-Early Cretaceous abyssal chert and siliceous shale with blocks of chert and mafic to ultra-mafic rocks. The Tangga mélange was accreted beneath ophiolitic rocks during the Aptian. The Pomunong mélange consists of a Late Jurassic-Early Cretaceous hemipelagic siliceous shale and chert matrix with blocks from Early Permian seamounts and from Late Cretaceous trench-fill sandstones; it was accreted beneath the Tangga mélange after the Aptian but prior to 71 Ma. Structurally beneath these mélanges to the south, the uppermost Cretaceous Rongmawa Formation consists of turbiditic sandstone, pelagic chert, and siliceous shale and records a transition in depositional setting from lower abyssal plain to upper trench. Detrital zircons from sandstone blocks of the Pomunong mélange and the coherent Rongmawa Formation display similar U-Pb age spectra and are dominated by peaks at 71-231 Ma, 481-693 Ma, and 701-1372 Ma. These age peaks overlap with igneous crystallization ages and detrital zircon ages from sedimentary strata in the Lhasa terrane. Our data indicate that the serpentinite mélange, Tangga mélange, Pomunong mélange and Rongmawa Formation comprise a southward-younging accretionary complex that developed during the northward subduction of Neo-Tethyan oceanic lithosphere beneath the south margin of the Lhasa terrane and that all exposed ophiolitic and accretionary complex assemblages

  11. The medium dispersion prism of the UK Schmidt Telescope

    NASA Astrophysics Data System (ADS)

    Cannon, R. D.; Dawe, J. A.; Morgan, D. H.; Savage, A.; Smith, M. G.

    The UK 1.2-m Schmidt Telescope acquired its first full aperture objective prism in 1975. This was a very low dispersion prism which was found to be particularly useful in searching for faint QSO's. However, the dispersion in the red is so low that nearly all plates have been taken on the blue-sensitive IIIa J emulsion, and it has been extremely difficult to identify quasars with redshifts larger than z=3. It was, therefore, decided to obtain a second objective prism having a three times higher dispersion. It is expected that this prism will make it possible to conduct searches for quasars having redshifts greater than the long-standing limit at z approximately 3.5. The prism should also be useful for stellar classification work in the UV/blue part of the spectrum. A description is presented of some results obtained during the recent commissioning run with the new prism.

  12. The PRISM (Pliocene Palaeoclimate) reconstruction: Time for a paradigm shift

    USGS Publications Warehouse

    Dowsett, Harry J.; Robinson, Marci M.; Stoll, Danielle K.; Foley, Kevin M.; Johnson, Andrew L. A.; Williams, Mark; Riesselman, Christina

    2013-01-01

    Global palaeoclimate reconstructions have been invaluable to our understanding of the causes and effects of climate change, but single-temperature representations of the oceanic mixed layer for data–model comparisons are outdated, and the time for a paradigm shift in marine palaeoclimate reconstruction is overdue. The new paradigm in marine palaeoclimate reconstruction stems the loss of valuable climate information and instead presents a holistic and nuanced interpretation of multi-dimensional oceanographic processes and responses. A wealth of environmental information is hidden within the US Geological Survey's Pliocene Research,Interpretation and Synoptic Mapping (PRISM) marine palaeoclimate reconstruction, and we introduce here a plan to incorporate all valuable climate data into the next generation of PRISM products. Beyond the global approach and focus, we plan to incorporate regional climate dynamics with emphasis on processes, integrating multiple environmental proxies wherever available in order to better characterize the mixed layer, and developing a finer time slice within the Mid-Piacenzian Age of the Pliocene, complemented by underused proxies that offer snapshots into environmental conditions. The result will be a proxy-rich, temporally nested, process-oriented approach in a digital format—a relational database with geographic information system capabilities comprising a three-dimensional grid representing the surface layer, with a plethora of data in each cell.

  13. The PRISM (Pliocene palaeoclimate) reconstruction: time for a paradigm shift.

    PubMed

    Dowsett, Harry J; Robinson, Marci M; Stoll, Danielle K; Foley, Kevin M; Johnson, Andrew L A; Williams, Mark; Riesselman, Christina R

    2013-10-28

    Global palaeoclimate reconstructions have been invaluable to our understanding of the causes and effects of climate change, but single-temperature representations of the oceanic mixed layer for data-model comparisons are outdated, and the time for a paradigm shift in marine palaeoclimate reconstruction is overdue. The new paradigm in marine palaeoclimate reconstruction stems the loss of valuable climate information and instead presents a holistic and nuanced interpretation of multi-dimensional oceanographic processes and responses. A wealth of environmental information is hidden within the US Geological Survey's Pliocene Research, Interpretation and Synoptic Mapping (PRISM) marine palaeoclimate reconstruction, and we introduce here a plan to incorporate all valuable climate data into the next generation of PRISM products. Beyond the global approach and focus, we plan to incorporate regional climate dynamics with emphasis on processes, integrating multiple environmental proxies wherever available in order to better characterize the mixed layer, and developing a finer time slice within the Mid-Piacenzian Age of the Pliocene, complemented by underused proxies that offer snapshots into environmental conditions. The result will be a proxy-rich, temporally nested, process-oriented approach in a digital format-a relational database with geographic information system capabilities comprising a three-dimensional grid representing the surface layer, with a plethora of data in each cell. PMID:24043866

  14. Wollaston prism phase-stepping point diffraction interferometer and method

    DOEpatents

    Rushford, Michael C.

    2004-10-12

    A Wollaston prism phase-stepping point diffraction interferometer for testing a test optic. The Wollaston prism shears light into reference and signal beams, and provides phase stepping at increased accuracy by translating the Wollaston prism in a lateral direction with respect to the optical path. The reference beam produced by the Wollaston prism is directed through a pinhole of a diaphragm to produce a perfect spherical reference wave. The spherical reference wave is recombined with the signal beam to produce an interference fringe pattern of greater accuracy.

  15. Prism fingerprint sensor that uses a holographic optical element

    NASA Astrophysics Data System (ADS)

    Bahuguna, R. D.; Corboline, Tom

    1996-09-01

    A prism fingerprint sensor is described that uses a holographic grating glued to a right-angled prism. A light source normally illuminates the hypotenuse side of the prism with the finger pressed against the grating. The ridges and valleys of the finger are sensed on the basis of the principle of total internal reflection. The grating is used essentially to correct the distortion usually present with prism sensors. The quality of the fingerprint is very good: the pores on the ridges can be seen.

  16. Late Proterozoic evolution of the northern part of the Hamisana zone, northeast Sudan - Constraints on Pan-African accretionary tectonics

    NASA Technical Reports Server (NTRS)

    Miller, M. M.; Dixon, T. H.

    1992-01-01

    This paper describes deformation fabrics developed in the northern part of the Hamisana zone in northeast Sudan. New structural data are presented which establish a structural chronology that characterizes distinct events of accretion, folding, and thrust faulting and reactivation of accretion-related faults. The structural data point to an intraplate compressional origin for the Hamisana zone. A review of available isotopic age data is carried out, and it is concluded that Pan-African accretionary processes may have been analogous to Phanerozoic ophiolite and island arc accretion in the western North American Cordillera, where penetrative deformation occurred in response to periodic intraplate shortening events, rather than an ultimate collision of unrelated crustal fragments.

  17. Oceanic, island arc, and back-arc remnants into eastern Kamchatka accretionary complexes

    SciTech Connect

    Fedorchuk, A.V.; Vishnevskaya, V.S.; Izvekov, I.N. )

    1990-06-01

    The Kamchatsky Mts. accretionary complex in the Eastern Kamchatka orogenic belt was studied for identification of the oceanic and suprasubduction components into accretionary wedges. That complex is divided into two tectonic units. The Lower unit is formed sedimentary and tectonic melanges containing arc-related components (Late Senonian volcaniclastics and boninitic gabbro) and oceanic fragments (Fe-Ti-tholeiites, ocean island basalts, and pelagic sediments of Valanginian to Turonian age). The Upper unit consists of ductile deformed oceanic cumulates from troctolites to Fe-Ti-gabbro, 151 to 172 Ma, which are intruded MORB-like diabases with suprasubduction characteristics, 122 to 141 Ma, and are overlain by basalts similar to latter. The Lower and Upper units are separated by a SW-dipping thrust, which is related by an ophiolitoclastic olistostrome of Late Campanian to Early Maestrichtian age. Both units are covered by Paleocene authoclastic deposits. They are all thrusted over the early Neogene island arc complex, 16 to 20 Ma. The Lower unit of the Kamchatsky Mys accretionary complex was originated in a shear zone between a Late Cretaceous island arc and an Early Cretaceous oceanic plate. The Upper unit represents a Jurassic oceanic remnant that formed a basement of Early Cretaceous back-arc or fore-arc basin. Both units were superposed in the latest Cretaceous. The Kamchatsky Mys accretionary complex was emplaced into the Eastern Kamchatka orogenic belt during late Neogene by collision of the early Neogene island arc.

  18. Prism adaptation in the healthy brain: the shift in line bisection judgments is long lasting and fluctuates.

    PubMed

    Schintu, Selene; Pisella, Laure; Jacobs, Stéphane; Salemme, Romeo; Reilly, Karen T; Farnè, Alessandro

    2014-01-01

    Rightward prism adaptation has been shown to ameliorate visuospatial biases in right brain-damaged patients with neglect, and a single session of prism adaptation can lead to improvements that last up to several hours. Leftward prism adaptation in neurologically healthy individuals induces neglect-like biases in visuospatial tasks. The duration of these effects in healthy individuals, typically assumed to be ephemeral, has never been investigated. Here we assessed the time-course of the adaptation-induced modifications in a classical perceptual line bisection task that was repeatedly administered for approximately 40min after a single session of adaptation to either a leftward or rightward prismatic deviation. Consistent with previous reports, only adaptation to leftward-deviating prisms induced a visuospatial shift on perceptual line bisection judgments. The typical pattern of pseudoneglect was counteracted by a rightward shift in midline judgments, which became significant between 5 and 10 min after adaptation, fluctuated between being significant or not several times in the 40 min following adaptation, and was present as late as 35 min. In contrast, the sensorimotor aftereffect was present immediately after adaptation to both rightward and leftward deviating prisms, decayed initially then remained stable until 40 min. These results demonstrate that both the sensorimotor and visuospatial effects last for at least 35 min, but that the visuospatial shift needs time to fully develop and fluctuates. By showing that the effects of prism adaptation in the undamaged brain are not ephemeral, these findings reveal the presence of another, so-far neglected dimension in the domain of the cognitive effects induced by prism adaptation, namely time. The prolonged duration of the induced visuospatial shift, previously considered to be a feature of prism adaptation unique to brain-damaged subjects, also applies to the normal brain. PMID:24291512

  19. Evaluation of the Performance of Routine Information System Management (PRISM) framework: evidence from Uganda

    PubMed Central

    2010-01-01

    Background Sound policy, resource allocation and day-to-day management decisions in the health sector require timely information from routine health information systems (RHIS). In most low- and middle-income countries, the RHIS is viewed as being inadequate in providing quality data and continuous information that can be used to help improve health system performance. In addition, there is limited evidence on the effectiveness of RHIS strengthening interventions in improving data quality and use. The purpose of this study is to evaluate the usefulness of the newly developed Performance of Routine Information System Management (PRISM) framework, which consists of a conceptual framework and associated data collection and analysis tools to assess, design, strengthen and evaluate RHIS. The specific objectives of the study are: a) to assess the reliability and validity of the PRISM instruments and b) to assess the validity of the PRISM conceptual framework. Methods Facility- and worker-level data were collected from 110 health care facilities in twelve districts in Uganda in 2004 and 2007 using records reviews, structured interviews and self-administered questionnaires. The analysis procedures include Cronbach's alpha to assess internal consistency of selected instruments, test-retest analysis to assess the reliability and sensitivity of the instruments, and bivariate and multivariate statistical techniques to assess validity of the PRISM instruments and conceptual framework. Results Cronbach's alpha analysis suggests high reliability (0.7 or greater) for the indices measuring a promotion of a culture of information, RHIS tasks self-efficacy and motivation. The study results also suggest that a promotion of a culture of information influences RHIS tasks self-efficacy, RHIS tasks competence and motivation, and that self-efficacy and the presence of RHIS staff have a direct influence on the use of RHIS information, a key aspect of RHIS performance. Conclusions The study

  20. Early Paleozoic accretionary orogenesis along northern margin of Gondwana constrained by high-Mg metaigneous rocks, SW Yunnan

    NASA Astrophysics Data System (ADS)

    Xing, Xiaowan; Wang, Yuejun; Cawood, Peter A.; Zhang, Yuzhi

    2015-12-01

    SW Yunnan of China constituted part of the northern margin of Gondwana facing the proto-Tethys ocean in the early Paleozoic. However, the evolution of the region and its relationship with the accretionary orogenism have been poorly established. This paper reports a set of new zircon U-Pb age data and whole-rock major oxides, elemental and Sr-Nd isotopic data for early Paleozoic metavolcanic rocks from the previously defined Lancang Group and reveals the development of an Ordovician suprasubduction zone in SW Yunnan. Zircon U-Pb ages of 462 ± 6 and 454 ± 27 Ma for two representative samples indicate eruption of the volcanic rocks in the Late Ordovician. Geochemical data for the metavolcanic rocks together with other available data indicate a calc-alkaline affinity with high Al2O3 (13.04-18.77 wt%) and low TiO2 (0.64-1.00 wt%). They have Mg-numbers ranging from 62 to 50 with SiO2 of 53.57-69.10 wt%, compositionally corresponding to the high-Mg andesitic rocks. They display enrichments in LREEs and LILEs with significant Eu negative anomalies (δEu = 0.20-0.33), and depletions in HFSEs, similar to arc volcanic rocks. Their initial 87Sr/86Sr ratios range from 0.721356 to 0.722521 and ɛNd(t) values from -7.63 to -7.62 with Nd model ages of 2.06-2.10 Ga. Integration of ages and geochemical data with available geological observations, we propose the presence of Ordovician magmatism related to proto-Tethyan evolution in SW Yunnan and the metaigneous rocks formed in an island-arc setting. They were part of a regional accretionary orogen that extended along the northern margin of Gondwana during Neoproterozoic to early Paleozoic period.

  1. Sources of Low-Chloride Fluids in Sediments beneath Biological Communities on the Nankai Accretionary Wedge off Kumano

    NASA Astrophysics Data System (ADS)

    Toki, T.; Tsunogai, U.; Gamo, T.; Kuramoto, S.; Ashi, J.

    2003-12-01

    We report chemical and isotopic compositions of interstitial waters extracted from surface sediments inside and outside of dense biological communities on the seafloor of the Nankai accretionary prism off Kumano. Particularly those taken within bacterial mat at the Oomine Ridge site show the following characteristics: (1) CH4 enrichment (more than 600 μ mol/kg), (2) chloride depletion (up to 10% depletion from bottom seawater), and (3) δ DH2O and δ 18OH2O depletion (more than 4‰ and 0.7‰ depletion, respectively), compared with bottom seawater. The highest CH4 value observed at the Oomine Ridge samples is compatible with that previously reported at one of the most active seep areas within Nankai Trough, suggesting that also this site should be one of the most active seep sites in Nankai Trough. The fluid chemistries of these samples show that the fluids of CH4 enrichment, chloride depletion, and low δ DH2O and δ 18OH2O value relative to bottom seawater are ascending from deeper zone to sediments beneath the Oomine Ridge site. Assuming simple two-component mixing of ambient seawater with fresh water of Cl- = 0 mmol/kg, the estimated end-member δ DH2O and δ 18OH2O values were -46+/-7‰ SMOW and -6.3+/-0.7‰ SMOW, respectively. The δ DH2O and δ 18OH2O values coincide with those of groundwater at nearby land area. Land-derived groundwater could be one of the possible sources for the low chloride fluids, while we donOt have any idea for such underground lateral flow system of groundwater to the depth of ca. 2,500 m and ca. 100 km off the Japan Islands. Alternative possible source to produce the fluid of low Cl-, δ DH2O and δ 18OH2O is phase separation of seawater. Phase separation would lower Cl-, δ DH2O and δ 18OH2O of vapor phase by a fractionation process during boiling, while we have no idea for a heat source to induce phase separation at the area. Fault slips during large earthquake could possibly be result in such source of heat.

  2. Structure of a paleo subduction décollement, Suzume Fault, Okitsu Mélange, Shimanto Accretionary Complex, Japan

    NASA Astrophysics Data System (ADS)

    Kanaya, T.; Chester, F. M.; Sakaguchi, A.

    2011-12-01

    The Suzume fault is an internal thrust of an exhumed duplex of underplated rock in the Shimanto accretionary complex. On the basis of structure, age, and paleo-temperature of rock in the duplex, the thrust is a subduction décollement exhumed from the shallow region of the seismogenic zone. Mesoscale structure of the thrust was characterized to investigate slip processes and structural evolution of the décollement. The thrust exhibits an asymmetric structure characterized by a decimeter-thick ultracataclasite bounded by a several-meter-thick zone of fractured basalt in the hanging wall and a 20-meter-thick zone of ductily sheared sedimentary rock in the footwall. The structure of the thrust is similar to that of active décollements drilled at the frontal portions of prisms, but differs in the greater intensity of ductile deformation and the occurrence of ultracataclasite. Hence, the footwall of the Suzume fault records aseismic, distributed shear in poorly consolidated sediment during shallow underthrusting followed by coseismic, localized-slip in lithified sedimentary rock during underplating at depth. The hanging wall, in contrast, records only the later stage of coseismic, localized-slip associated with underplating. The ultracataclasite layers in the Suzume fault exhibit shear localization onto a through-going fracture surface and fabrics indicative of distributed flow, which are likely associated with the seismic cycle, i.e., alternating co- and inter-seismic slip. Off-fault fracture fabric in the hanging wall, related to thrusting at depth, records predominantly up-dip propagation of fault slip events. /// A synthesis of observations of ~20 subduction megathrusts representing the 0-15 km depth range, combined with the findings from the Suzume fault and modern Nankai megathrusts, documents a systematic decrease in the thickness of the slip zone, changes in deformation mechanisms and fluid-rock reactions, and an increase in shear heating, with depth. These

  3. Manganese formations in the accretionary belts of Japan: Implications for subduction-accretion process in an active convergent margin

    NASA Astrophysics Data System (ADS)

    Nakagawa, M.; Santosh, M.; Maruyama, S.

    2011-08-01

    In the accretionary complexes of Japan, many bedded manganese and iron-manganese ore deposits occur, especially in the Jurassic complexes such as the Chichibu, Tamba, Mino, Ashio and Northern Kitakami belts. The manganese ores in these Jurassic accretionary complexes probably formed from manganese nodule/crust-bearing siliceous sediments on deep-sea floor and were subsequently converted to the manganese ores by metamorphism during the subduction-accretion process. Some of the deposits also show the signatures of younger granitic intrusions. The manganese formations now incorporated within these belts are marker beds of accretionary tectonics associated with plate tectonic processes in convergent margins.

  4. Priorities in School Mathematics: Executive Summary of the PRISM Project.

    ERIC Educational Resources Information Center

    National Council of Teachers of Mathematics, Inc., Reston, VA.

    The Priorities in School Mathematics Project (PRISM) was designed by the National Council of Teachers of Mathematics to collect information on current beliefs and reactions to possible mathematics curriculum changes during the 1980's. The first component of PRISM was a survey of preferences for alternative content topics, instructional goals,…

  5. Décollement processes at the Nankai accretionary margin, southeast Japan: Propagation, deformation, and dewatering

    NASA Astrophysics Data System (ADS)

    Morgan, Julia K.; Karig, Daniel E.

    1995-08-01

    The décollement zone, expressed on seismic profiles and observed in drill cores from the Nankai accretionary margin off the southeast coast of Japan, reveals several unique characteristics which appear to distinguish it from thrust faults identified in the same setting. Physical manifestations of these include evidence for the asymmetric distribution of deformation structures about the décollement, the extension of this fault zone well in front of the tectonic deformation front, and the absence of features indicative of precursory shear, for example, folded sediments, shear bands, and penetrative mineral fabrics. These characteristics suggest that the mode of formation and evolution of this décollement zone may be unique from that of most thrust faults. We propose that the décollement zone propagates not as a shear fracture controlled by tectonic stress conditions but rather as a subhorizontal tension fracture propagating under high pore pressures. To test this possibility, physical property measurements and clay mineral fabrics were obtained for several samples from the Nankai décollement zone using computed tomography and X ray texture methods. Our findings suggest that deformation within the décollement zone is partitioned into a volumetric component, preserved as reduced porosities within coherent fragments, and a localized shear component, evidenced by mineral preferred orientations along discrete slip surfaces. We suggest that the reduced porosities result from the destruction of "cementation" in the sediments during the early stages of deformation and may arise from cyclic fatiguing of the sediment induced by fluctuating pore pressures. The nonpenetrative shear fabrics probably develop as the tectonic deformation front migrates seaward, and the weakened protodécollement subsequently accommodates shear displacements along discrete fractures.

  6. The PRISM project: Infrastructure and algorithms for parallel eigensolvers

    SciTech Connect

    Bischof, C.; Sun, X.; Huss-Lederman, S.; Tsao, A.

    1993-12-31

    The goal of the PRISM project is the development of infrastructure and algorithms for the parallel solution of eigenvalue problems. We are currently investigating a complete eigensolver based on the Invariant Subspace Decomposition Algorithm for dense symmetric matrices (SYISDA). After briefly reviewing the SYISDA approach, we discuss the algorithmic highlights of a distributed-memory implementation of an eigensolver based on this approach. These include a fast matrix-matrix multiplication algorithm, a new approach to parallel band reduction and tridiagonalization, and a harness for coordinating the divide-and-conquer parallelism in the problem. We also present performance results of these kernels as well as the overall SYISDA implementation on the Intel Touchstone Delta prototype and the IBM SP/1.

  7. Foreword: contributions of Arctic PRISM to monitoring western hemispheric shorebirds

    USGS Publications Warehouse

    Skagen, Susan K.; Smith, Paul A.; Andres, Brad A.; Donaldson, Garry; Brown, Stephen

    2012-01-01

    listing under the U.S. Endangered Species Act and the Canadian Species at Risk Act. To meet the need for information on population size and trends, shorebird biologists from Canada and the United States proposed a shared blueprint for shorebird monitoring across the Western Hemisphere in the late 1990s; this effort was undertaken in concert with the development of the Canadian and the U.S. Shorebird Conservation Plans. Soon thereafter, partners in the monitoring effort adopted the name "Program for Regional and International Shorebird Monitoring" (PRISM). Among the primary objectives of PRISM were to estimate the population sizes and trends of breeding North American shorebirds and describe their distributions. PRISM members evaluated ongoing and potential monitoring approached to address 74 taxa (including subspecies) and proposed a combination of arctic and boreal breeding surveys, temperate breeding and non-breeding surveys, and neotropical surveys.

  8. Contributions of Arctic PRISM to monitoring western hemispheric shorebirds

    USGS Publications Warehouse

    Skagen, Susan K.; Smith, Paul A.; Andres, Brad A.; Donaldson, Garry; Brown, Stephen

    2012-01-01

    for assessing its vulnerability and subsequent listing under the U.S. Endangered Species Act and the Canadian Species at Risk Act. To meet the need for information on population size and trends, shorebird biologists from Canada and the United States proposed a shared blueprint for shorebird monitoring across the Western Hemisphere in the late 1990s; this effort was undertaken in concert with the development of the Canadian and U.S. Shorebird Conservation Plans (Donaldson et al. 2000, Brown et aL 2001). Soon thereafter, partners in the monitoring effort adopted the name "Program for Regional and International Shorebird Monitoring" (PRISM). Among the primary objectives of PRISM were to estimate the population sizes and trends of breeding North American shorebirds and describe their distributions (Bart et al. 2002). PRISM members evaluated ongoing and potential monitoring approaches to address 74 taxa (including subspecies) and proposed a combination of arctic andboreal breeding surveys, temperate breeding and non-breeding surveys, and neotropical surveys.

  9. Inverse solutions for a Risley prism scanner with iterative refinement by a forward solution.

    PubMed

    Li, Anhu; Gao, Xinjian; Sun, Wansong; Yi, Wanli; Bian, Yongming; Liu, Hongzhan; Liu, Liren

    2015-11-20

    Risley prism scanners are increasingly used for laser beam steering due to their wide angular scanning range and high resolution. However, the inverse problem, which focuses on obtaining the required prisms' orientations for a given target position, has not been perfectly solved so far. The existing inverse solutions are not accurate or efficient enough for high-accuracy and real-time tracking. An iterative method that combines an approximate inverse solution with an iterative refinement by the forward solution is set forth in this paper. Two case studies indicate that the rotation motions of Risley prism pairs controlled by iterative solutions can slew the beam to create the desired tracking pattern quickly and accurately. Based on this method, a Risley prism scanner developed as a standard trajectory generator is implemented for the error measurement of a robotic manipulator in our experiments. The simulation and experimental results show that the inverse solution for one target point can be obtained within nine iterations for a prescribed tracking error threshold. PMID:26836567

  10. Triassic deformation of Permian Early Triassic arc-related sediments in the Beishan (NW China): Last pulse of the accretionary orogenesis in the southernmost Altaids

    NASA Astrophysics Data System (ADS)

    Tian, Zhonghua; Xiao, Wenjiao; Sun, Jimin; Windley, Brian F.; Glen, Richard; Han, Chunming; Zhang, Zhiyong; Zhang, Ji'en; Wan, Bo; Ao, Songjian; Song, Dongfang

    2015-11-01

    The Beishan orogenic collage (BOC) in the southernmost Altaids provides evidence of the final stage of evolution of the Paleo-Asian Ocean. However, the closure time of the Paleo-Asian Ocean in the BOC is controversial. From field mapping, and structural analysis of mesoscale, superposed folds in Early Triassic sediments in the Hongyanjing Basin in the central BOC, we define at least two phases of deformation, which we can bracket in age as end-Permian to Early-Late Triassic. The sandstones in the basin are poorly sorted with angular clasts, which indicates immaturity characteristic of proximal and rapid deposition. Geochemical data indicate that the Hongyanjing Basin probably developed in an arc-related setting near an active continental margin or mature island arc. Combined with published regional geological data, we interpret the Hongyanjing Basin as a Permian-Early Triassic inter-arc basin between the Carboniferous Mazongshan arc to the north and the Ordovician to Permian Huaniushan-Dundunshan arc to the south. In addition, the age distribution of our sediments shows that the active continental margin or continental arc on which the Hongyanjing arc-related basin sat was somehow independently distributed in the Paleo-Asian Ocean without any major contribution of provenance from the Tarim Craton and Dunhuang Block to the south and Southern Mongolia accretionary system to the north. Deformation of the superposed folds began in the end-Permian, continued in the Early Triassic, and ended before the middle Late Triassic (219 Ma). Therefore the accretionary orogenesis in the Beishan part of the southernmost Altaids was still ongoing in the early to middle Triassic, and it finished in the Late Triassic, which might have been the last pulse of the accretionary orogenesis in the southernmost Altaids. We correlate this terminal event with tectonic developments in the Kunlun and Qinling orogens in the Tethyan domain.

  11. Paleozoic subduction erosion involving accretionary wedge sediments in the South Tianshan Orogen: Evidence from geochronological and geochemical studies on eclogites and their host metasediments

    NASA Astrophysics Data System (ADS)

    Liu, Xin; Su, Wen; Gao, Jun; Li, Jilei; Jiang, Tuo; Zhang, Xi; Ge, Xiaomei

    2014-12-01

    Geochronological and geochemical data regarding eclogites and their metasedimentary host rocks exposed in two localities of the South Tianshan (U)HP-LT metamorphic belt are presented to reveal the protolith of the eclogites and the provenance of the metasediments. The rim domains of zircon grains from the eclogites contain omphacite, phengite and rutile inclusions and give a U-Pb Concordia age of 321.4 ± 2.4 Ma, representing the peak of eclogite-facies metamorphism. The core domains of zircon grains with magmatic oscillatory zoning yield a U-Pb Concordia age of 453.9 ± 9.4 Ma, suggesting a Late Ordovician age for the eclogites' protolith. Furthermore, the inherited cores of some zircon grains have apparent U-Pb ages between 609 Ma and 2305 Ma, implying the involvement of the Precambrian basement in the formation of the eclogites' protolith. The depletion of high field strength elements and the trace element ratios indicate the eclogite protolith's continental arc affinity. The zircon U-Pb age data of the high-pressure micaschists yield seven age groups ranging from 401 Ma to 3201 Ma and cluster at a pronounced peak of ~ 445 Ma. The major and trace element compositions of the micaschists overlap those of the average upper continental crust. The protolith of the micaschist seems to have formed at an accretionary wedge, which is predominantly composed of sediments derived from Ordovician-Silurian arc-type magmatic rocks and Precambrian basement rocks in an active continental margin. The basic blocks represented by the protolith of the eclogites were most likely scraped from the basement of a continental arc by basal erosion during the subduction of the South Tianshan Ocean in Late Paleozoic. At the same time, the fragments composing the micaschists' protolith are believed to have been dragged into the subduction channel by the frontal erosion of the accretionary prism. Both the basic blocks and the sediment fragments were forced into the subduction channel, mingled

  12. Metatranscriptomic Analysis of Diminutive Thiomargarita-Like Bacteria (“Candidatus Thiopilula” spp.) from Abyssal Cold Seeps of the Barbados Accretionary Prism

    PubMed Central

    Flood, Beverly E.

    2015-01-01

    Large sulfur-oxidizing bacteria in the family Beggiatoaceae are important players in the global sulfur cycle. This group contains members of the well-known genera Beggiatoa, Thioploca, and Thiomargarita but also recently identified and relatively unknown candidate taxa, including “Candidatus Thiopilula” spp. and “Ca. Thiophysa” spp. We discovered a population of “Ca. Thiopilula” spp. colonizing cold seeps near Barbados at a ∼4.7-km water depth. The Barbados population consists of spherical cells that are morphologically similar to Thiomargarita spp., with elemental sulfur inclusions and a central vacuole, but have much smaller cell diameters (5 to 40 μm). Metatranscriptomic analysis revealed that when exposed to anoxic sulfidic conditions, Barbados “Ca. Thiopilula” organisms expressed genes for the oxidation of elemental sulfur and the reduction of nitrogenous compounds, consistent with their vacuolated morphology and intracellular sulfur storage capability. Metatranscriptomic analysis further revealed that anaerobic methane-oxidizing and sulfate-reducing organisms were active in the sediment, which likely provided reduced sulfur substrates for “Ca. Thiopilula” and other sulfur-oxidizing microorganisms in the community. The novel observations of “Ca. Thiopilula” and associated organisms reported here expand our knowledge of the globally distributed and ecologically successful Beggiatoaceae group and thus offer insight into the composition and ecology of deep cold seep microbial communities. PMID:25724961

  13. Prioritization Risk Integration Simulation Model (PRISM) For Environmental Remediation and Waste Management - 12097

    SciTech Connect

    Pentz, David L.; Stoll, Ralph H.; Greeves, John T.; Miller, R. Ian; Nutt, W. Mark

    2012-07-01

    The PRISM (Prioritization Risk Integration Simulation Model), a computer model was developed to support the Department of Energy's Office of Environmental Management (DOE-EM) in its mission to clean up the environmental legacy from the Nation's nuclear weapons materials production complex. PRISM provides a comprehensive, fully integrated planning tool that can tie together DOE-EM's projects. It is designed to help DOE managers develop sound, risk-informed business practices and defend program decisions. It provides a better ability to understand and manage programmatic risks. The underlying concept for PRISM is that DOE-EM 'owns' a portfolio of environmental legacy obligations (ELOs), and that its mission is to transform the ELOs from their current conditions to acceptable conditions, in the most effective way possible. There are many types of ELOs - - contaminated soils and groundwater plumes, disused facilities awaiting D and D, and various types of wastes waiting for processing or disposal. For a given suite of planned activities, PRISM simulates the outcomes as they play out over time, allowing for all key identified uncertainties and risk factors. Each contaminated building, land area and waste stream is tracked from cradle to grave, and all of the linkages affecting different waste streams are captured. The progression of the activities is fully dynamic, reflecting DOE-EM's prioritization approaches, precedence requirements, available funding, and the consequences of risks and uncertainties. The top level of PRISM is the end-user interface that allows rapid evaluation of alternative scenarios and viewing the results in a variety of useful ways. PRISM is a fully probabilistic model, allowing the user to specify uncertainties in input data (such as the magnitude of an existing groundwater plume, or the total cost to complete a planned activity) as well as specific risk events that might occur. PRISM is based on the GoldSim software that is widely used for risk

  14. Motion control of the wedge prisms in Risley-prism-based beam steering system for precise target tracking.

    PubMed

    Zhou, Yuan; Lu, Yafei; Hei, Mo; Liu, Guangcan; Fan, Dapeng

    2013-04-20

    Two exact inverse solutions of Risley prisms have been given by previous authors, based on which we calculate the gradients of the scan field that open a way to investigate the nonlinear relationship between the slewing rate of the beam and the required angular velocities of the two wedge prisms in the Risley-prism-based beam steering system for target tracking. The limited regions and singularity point at the center and the edge of the field of regard are discussed. It is found that the maximum required rotational velocities of the two prisms for target tracking are nearly the same and are dependent on the altitude angle. The central limited region is almost independent of the prism parameters. The control singularity at the crossing center path can be avoided by switching the two solutions. PMID:23669697

  15. Testing the PRISM Temperature Model in Complex Terrain: Implications for Mountain Ecohydrology

    NASA Astrophysics Data System (ADS)

    Strachan, S.; Daly, C.; Millar, C.

    2015-12-01

    Studies in mountainous terrain related to ecology and hydrology often use interpolated climate products because of a lack of local observations. One dataset frequently used to develop plot-to-watershed scale climatologies is the PRISM (Parameter-elevation Regression on Independent Slopes Model) temperature model. Benefits of this approach include geographically-weighted station observations and topographic positioning modifiers, which become important factors for predicting temperature in complex topography. Because of the paucity of long-term climate records in mountain environments, validation of PRISM algorithms across diverse regions remains challenging, with end users instead relying on atmospheric relationships derived in sometimes distant geographic settings. Recent developments of the PRISM model have increased temporal resolution capability from monthly to daily, which in turn has allowed a reasonable test of PRISM performance during a single season at distributed points across a large watershed. Presented are results from testing instrumental observations of daily max/min temperature on 16 sites in the Walker Basin, CA-NV, located on open woodland slopes ranging from 1967 to 3111 m in elevation. Individual site MAE varies from 1.34 to 4.22 C with better performance observed during summertime as opposed to winter. We observe a consistent bias in minimum temperatures for all seasons across all sites, with bias in maximum temperatures varying with season. Model error for minimum is associated strongly with elevation, whereas model error for maximum is associated with topographic radiative indices (solar exposure and heat loading). These results indicate that actual temperature conditions across open mountain woodland slopes are more heterogeneous than interpolated models (such as PRISM) indicate, which in turn impacts prediction/modeling of landscape processes such as ecological niches, bioclimatic refugia, and snow hydrology.

  16. Active stereo vision routines using PRISM-3

    NASA Astrophysics Data System (ADS)

    Antonisse, Hendrick J.

    1992-11-01

    This paper describes work in progress on a set of visual routines and supporting capabilities implemented on the PRISM-3 real-time vision system. The routines are used in an outdoor robot retrieval task. The task requires the robot to locate a donor agent -- a Hero2000 -- which holds the object to be retrieved, to navigate to the donor, to accept the object from the donor, and return to its original location. The routines described here will form an integral part of the navigation and wide-area search tasks. Active perception is exploited to locate the donor using real-time stereo ranging directed by a pan/tilt/verge mechanism. A framework for orchestrating visual search has been implemented and is briefly described.

  17. Large beam deflection using cascaded prism array

    NASA Astrophysics Data System (ADS)

    Wang, Wei-Chih; Tsui, Chi-Leung

    2012-04-01

    Endoscopes have been utilize in the medical field to observe the internals of the human body to assist the diagnosis of diseases, such as breathing disorders, internal bleeding, stomach ulcers, and urinary tract infections. Endoscopy is also utilized in the procedure of biopsy for the diagnosis of cancer. Conventional endoscopes suffer from the compromise between overall size and image quality due to the required size of the sensor for acceptable image quality. To overcome the size constraint while maintaining the capture image quality, we propose an electro-optic beam steering device based on thermal-plastic polymer, which has a small foot-print (~5mmx5mm), and can be easily fabricated using conventional hot-embossing and micro-fabrication techniques. The proposed device can be implemented as an imaging device inside endoscopes to allow reduction in the overall system size. In our previous work, a single prism design has been used to amplify the deflection generated by the index change of the thermal-plastic polymer when a voltage is applied; it yields a result of 5.6° deflection. To further amplify the deflection, a new design utilizing a cascading three-prism array has been implemented and a deflection angle to 29.2° is observed. The new design amplifies the beam deflection, while keeping the advantage of simple fabrication made possible by thermal-plastic polymer. Also, a photo-resist based collimator lens array has been added to reduce and provide collimation of the beam for high quality imaging purposes. The collimator is able to collimate the exiting beam at 4 μm diameter for up to 25mm, which potentially allows high resolution image capturing.

  18. Seep carbonates and chemosynthetic coral communities in the Early Paleocene alpine accretionary wedge: evidences from the Bocco Shale (Internal Liguride ophiolitic sequence, Northern Apennine, Italy)

    NASA Astrophysics Data System (ADS)

    Pandolfi, Luca; Boschi, Chiara; Luvisi, Edoardo; Alessandro, Ellero; Marroni, Michele; Meneghini, Francesca

    2014-05-01

    In Northern Apennines, the Internal Liguride units are characterized by an ophiolite sequence that represents the stratigraphic base of a Late Jurassic-Early Paleocene sedimentary cover. The Bocco Shale represents the youngest deposit recognized in the sedimentary cover of the ophiolite sequence, sedimented just before the inception of subduction-related deformation history. The Bocco Shale has been interpreted as a fossil example of deposits related to the frontal tectonic erosion of the alpine accretionary wedge slope. The frontal tectonic erosion resulted in a large removal of material from the accretionary wedge front reworked as debris flows and slide deposits sedimented on the lower plate above the trench deposits. These trench-slope deposits may have been successively deformed and metamorphosed during the following accretion processes. The frontal tectonic erosion can be envisaged as a common process during the convergence-related evolution of the Ligure-Piemontese oceanic basin in the Late Cretaceous-Early Tertiary time span. In the uppermost Internal Liguride tectonic unit (Portello Unit of Pandolfi and Marroni. 1997), that crops-out in Trebbia Valley, several isolated blocks of authigenic carbonates, unidentificated corals and intrabasinal carbonatic arenites have been recognized inside the fine-grained sediments that dominate the Early Paleocene Lavagnola Fm. (cfr. Bocco Shale Auctt.). The preliminary data on stable isotopes from blocks of authigenic carbonates (up to 1 m thick and 3 m across) and associated corals archive a methane signatures in their depleted carbon isotope pattern (up to δ13C -30‰ PDB) and suggest the presence of chemosynthetic paleocommunities. The seep-carbonates recognized at the top of Internal Liguride succession (cfr. Bocco Shale Auctt.) occur predominantly as blocks in very thick mudstone-dominated deposits and probably developed in an environment dominated by the expulsion of large volume of cold methane-bearing fluids

  19. Provenance and origins of a Late Paleozoic accretionary complex within the Khangai-Khentei belt in the Central Asian Orogenic Belt, central Mongolia

    NASA Astrophysics Data System (ADS)

    Hara, Hidetoshi; Kurihara, Toshiyuki; Tsukada, Kazuhiro; Kon, Yoshiaki; Uchino, Takayuki; Suzuki, Toshiya; Takeuchi, Makoto; Nakane, Yuki; Nuramkhaan, Manchuk; Chuluun, Minjin

    2013-10-01

    We have investigated the petrography, geochemistry, and detrital zircon U-Pb LA-ICPMS dating of sandstone from the Gorkhi Formation of the Khangai-Khentei belt in the Ulaanbaatar area, central Mongolia. These data are used to constrain the provenance and source rock composition of the accretionary complex, which is linked to subduction of the Paleo-Asian Ocean within the Central Asian Orogenic Belt during the Middle Devonian to Early Carboniferous. Field and microscopic observations of the modal composition of sandstone and constituent mineral chemistry indicate that the sandstone of the Gorkhi Formation is feldspathic arenite, enriched in saussuritized plagioclase. Geochemical data show that most of the sandstone and shale were derived from a continental margin to continental island arc setting, with plutonic rocks being the source rocks. Detrital zircon 206Pb/238U ages of two sandstones yields age peaks of 322 ± 3 and 346 ± 3 Ma. The zircon 206Pb/238U age of a quartz-pumpellyite vein that cuts sandstone has a weighted mean age of 339 ± 3 Ma. Based on these zircon ages, we infer that the depositional age of sandstone within the Gorkhi Formation ranges from 320 to 340 Ma (i.e., Early Carboniferous). The provenance and depositional age of the Gorkhi Formation suggest that the evolution of the accretionary complex was influenced by the intrusion and erosion of plutonic rocks during the Early Carboniferous. We also suggest that spatial and temporal changes in the provenance of the accretionary complex in the Khangai-Khentei belt, which developed aound the southern continental margin of the Siberian Craton in relation to island arc activity, were influenced by northward subduction of the Paleo-Asian Ocean plate.

  20. Pure rotation of a prism on a ramp

    PubMed Central

    Zhao, Zhen; Liu, Caishan; Ma, Daolin

    2014-01-01

    In this work, we study a prism with a cross section in polygon rolling on a ramp inclined at a small angle. The prism under gravity rolls purely around each individual edge, intermittently interrupted by a sequence of face collisions between the side face of the prism and the ramp. By limiting the prism in a planar motion, we propose a mathematical model to deal with the events of the impacts. With a pair of laser-Doppler vibrometers, experiments are also conducted to measure the motions of various prisms made of different materials and with different edge number. Not only are good agreements achieved between our numerical and experimental results, but also an intriguing physical phenomenon is discovered: the purely rolling motion is nearly independent of the prism's materials, yet it is closely related to the prism's geometry. Imagine that an ideal circular section can be approximately equivalent to a polygon with a large enough edge number N, the finding presented in this paper may help discover the physical mechanism of rolling friction. PMID:25197242

  1. Origin of accretionary lapilli from the Pompeii and Avellino deposits of Vesuvius

    SciTech Connect

    Sheridan, M.F.; Wohletz, K.H.

    1983-01-01

    Accretionary lapilli from the Pompeii and Avellino Plinian ash deposits of Vesuvius consist of centimeter-sized spheroids composed of glass, crystal, and lithic fragments of submillimeter size. The typical structure of the lapilli consists of a central massive core surrounded by concentric layers of fine ash with concentrations of larger clasts and vesicles and a thin outer layer of dust. Clasts within the lapilli larger than 125 ..mu..m are extremely rare. The median grain-size of the fine ash is about 50 ..mu..m and the size-distribution is well sorted. Most constituent particles of accretionary lapilli display blocky shapes characteristic of grains produced by phreatomagmatic hydroexplosions. We have used the scanning electron microscope (SEM) in conjunction with energy dispersive spectral analysis (EDS) to investigate the textural and chemical variation along traverses from the core to the rim of lapilli from Vesuvius.

  2. Estimating basal friction in accretionary wedges from the geometry and spacing of frontal faults

    NASA Astrophysics Data System (ADS)

    Schott, Bertram; Koyi, Hemin A.

    2001-12-01

    Elastic theory applied to the deformation in accretionary wedges is used to calculate the condition for slip along an active frontal fault and the basal décollement. The equations for calculating the stresses can be solved for the coefficient of basal friction in the situation of the formation of a new frontal thrust fault. This allows us to calculate the efficient coefficient of basal friction, which includes the weakening effect of pore-fluid pressure, from geometric parameters and material properties only. The geometric parameters, like fault dip and layer thickness, can be derived from high-resolution seismic cross-sections. Application of our analysis to the Makran and the Nankai accretionary wedge allows us to estimate the upper limit of the effective coefficient of basal friction, μb≈0.16 and μb≈0.2, in these two areas respectively.

  3. Hydrogeochemistry of the northern Barbados accretionary complex transect: Ocean Drilling Project leg 110

    SciTech Connect

    Gieskes, J.M. ); Vrolijk, P. ); Blanc, G. )

    1990-06-10

    Detailed studies of the major element geochemistry, oxygen and hydrogen isotope ratios of pore fluids, and the {sup 87}Sr/{sup 86}Sr ratio of dissolved strontium have made it possible to unravel physical and chemical processes that affect the pore fluid chemistry in a transect of drill holes across the northern Barbados accretionary complex. These processes include (1) alteration of volcanic ash buried in the Pleisticene-Pliocene sediment column; (2) alteration of underlying basalts of layer 2 of the oceanic crust; (3) movement of fluids from deep in the accretionary complex along fault zones (particularly the decollement) and minor permeable layers; these fluids from deeper in the complex are characterized by low chloride concentrations and increased {sup {delta}18}O(H{sub 2}O) values, presumably as a result of dehydration of smectite interlayers; and (4) mixing processes involving the migrating fluids cause incongruities in the geochemical anomalies of these fluids.

  4. The Personalized Reminder Information and Social Management System (PRISM) Trial: Rationale, Methods and Baseline Characteristics

    PubMed Central

    Czaja, Sara J.; Boot, Walter R.; Charness, Neil; Rogers, Wendy; Sharit, Joseph; Fisk, Arthur D.; Lee, Chin Chin; Nair, Sankaran N.

    2014-01-01

    Technology holds promise in terms of providing support to older adults. To date there have been limited robust systematic efforts to evaluate the psychosocial benefits of technology for older people and identify factors that influence both the usability and uptake of technology systems. In response to these issues we developed the Personal Reminder Information and Social Management System (PRISM), a software application designed for older adults to support social connectivity, memory, knowledge about topics, leisure activities and access to resources. This trail is evaluating the impact of access to the PRISM system on outcomes such as social isolation, social support and connectivity. This paper reports on the approach used to design the PRISM system, study design, methodology and baseline data for the trial. The trial is multi-site randomized field trial. PRISM is being compared to a Binder condition where participants received a binder that contained content similar to that found on PRISM. The sample includes 300 older adults, aged 65 – 98 years, who lived alone and at risk for being isolated. The primary outcome measures for the trial include indices of social isolation and support and well-being. Secondary outcomes measures include indices of computer proficiency, technology uptake and attitudes towards technology. Follow-up assessments occurred at 6 and 12 months post-randomization. The results of this study will yield important information about the potential value of technology for older adults. The study also demonstrates how a user-centered iterative design approach can be incorporated into the design and evaluation of an intervention protocol. PMID:25460342

  5. The personalized reminder information and social management system (PRISM) trial: rationale, methods and baseline characteristics.

    PubMed

    Czaja, Sara J; Boot, Walter R; Charness, Neil; A Rogers, Wendy; Sharit, Joseph; Fisk, Arthur D; Lee, Chin Chin; Nair, Sankaran N

    2015-01-01

    Technology holds promise in terms of providing support to older adults. To date, there have been limited robust systematic efforts to evaluate the psychosocial benefits of technology for older people and identify factors that influence both the usability and uptake of technology systems. In response to these issues, we developed the Personal Reminder Information and Social Management System (PRISM), a software application designed for older adults to support social connectivity, memory, knowledge about topics, leisure activities and access to resources. This trail is evaluating the impact of access to the PRISM system on outcomes such as social isolation, social support and connectivity. This paper reports on the approach used to design the PRISM system, study design, methodology and baseline data for the trial. The trial is multi-site randomized field trial. PRISM is being compared to a Binder condition where participants received a binder that contained content similar to that found on PRISM. The sample includes 300 older adults, aged 65-98 years, who lived alone and at risk for being isolated. The primary outcome measures for the trial include indices of social isolation and support and well-being. Secondary outcomes measures include indices of computer proficiency, technology uptake and attitudes towards technology. Follow-up assessments occurred at 6 and 12 months post-randomization. The results of this study will yield important information about the potential value of technology for older adults. The study also demonstrates how a user-centered iterative design approach can be incorporated into the design and evaluation of an intervention protocol. PMID:25460342

  6. Pre-collisional accretionary growth of the southern Laurasian active margin, Central Pontides, Turkey

    NASA Astrophysics Data System (ADS)

    Aygül, Mesut; Okay, Aral I.; Oberhänsli, Roland; Sudo, Masafumi

    2016-03-01

    Cretaceous subduction-accretionary complexes crop out over wide areas in the central part of the Pontides, northern Turkey. To the north, the wedge consists of a low-grade metaflysch sequence with blocks of marble, Na-amphibole-bearing metabasite (PT = 7-12 kbar; 400 ± 70 °C) and serpentinite. 40Ar/39Ar phengite ages from the phyllites of the metaflysch are ca. 100 Ma. The metaflysch sequence is underlain by oceanic crust-derived HP/LT metabasites and micaschists along a major detachment fault. The metabasites are epidote-blueschists consisting of glaucophane, epidote, titanite, and phengite locally with garnet. Fresh lawsonite-blueschists are exposed as blocks along the detachment fault. Peak metamorphic conditions of a garnet-blueschist are constrained to 17 ± 1 kbar and 500 ± 40 °C and of a lawsonite-blueschist to 14 ± 2 kbar and 370-440 °C. 40Ar/39Ar phengite dating on the micaschists constrains the HP/LT metamorphism as 101-92 Ma, younging southward. Middle Jurassic (ca. 160 Ma) accretionary complexes consisting of blueschist to lower greenschist facies metabasites, marble and volcanogenic metasediment intercalations are exposed at the southern part of the Cretaceous wedge. In the studied area, the North Anatolian Fault forms the contact between Cretaceous and Middle Jurassic HP/LT metamorphic rocks. Wide distribution of Cretaceous subduction-accretionary complexes implies accretionary tectonic continental growth along the Laurasian active margin. High amount of clastic sediment flux into the trench has a major effect on enlarging the wedge during the Albian. Tectonic thickening of the oceanic HP/LT metamorphic sequence, however, was possibly achieved by propagation of the décollement along the retreating slab which can create the space necessary for progressive deep level basal underplating and extension of the wedge for subsequent syn-subduction exhumation.

  7. Continuum percolation for randomly oriented soft-core prisms.

    PubMed

    Saar, Martin O; Manga, Michael

    2002-05-01

    We study continuum percolation of three-dimensional randomly oriented soft-core polyhedra (prisms). The prisms are biaxial or triaxial and range in aspect ratio over six orders of magnitude. Results for prisms are compared with studies for ellipsoids, rods, ellipses, and polygons and differences are explained using the concept of the average excluded volume, . For large-shape anisotropies we find close agreement between prisms and most of the above-mentioned shapes for the critical total average excluded volume, n(c), where n(c) is the critical number density of objects at the percolation threshold. In the extreme oblate and prolate limits simulations yield n(c) approximately 2.3 and n(c) approximately 1.3, respectively. Cubes exhibit the lowest-shape anisotropy of prisms minimizing the importance of randomness in orientation. As a result, the maximum prism value, n(c) approximately 2.79, is reached for cubes, a value close to n(c)=2.8 for the most equant shape, a sphere. Similarly, cubes yield a maximum critical object volume fraction of phi(c)=0.22. phi(c) decreases for more prolate and oblate prisms and reaches a linear relationship with respect to aspect ratio for aspect ratios greater than about 50. Curves of phi(c) as a function of aspect ratio for prisms and ellipsoids are offset at low-shape anisotropies but converge in the extreme oblate and prolate limits. The offset appears to be a function of the ratio of the normalized average excluded volume for ellipsoids over that for prisms, R=(e)/(p). This ratio is at its minimum of R=0.758 for spheres and cubes, where phi(c(sphere))=0.2896 may be related to phi c(cube))=0.22 by phi(c(cube))=1-[1-phi(c(sphere))](R)=0.23. With respect to biaxial prisms, triaxial prisms show increased normalized average excluded volumes, , due to increased shape anisotropies, resulting in reduced values of phi(c). We confirm that B(c)=n(c)=2C(c) applies to

  8. Image Quality Evalutation on ALOS/PRISM and AVNIR-2

    NASA Astrophysics Data System (ADS)

    Mukaida, Akira; Imoto, Naritoshi; Tadono, Takeo; Murakami, Hiroshi; Kawamoto, Sachi

    2008-11-01

    Image quality evaluation on ALOS (Advanced Land Observing Satellite) / PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping) and AVNIR-2 (Advanced Visible and Near Infrared Radiometer 2) has been carried out during operational phase. This is a report on result of evaluation for image quality in terms of MTF (Modulation Transfer Function) and SNR (Signal to Noise Ratio) for both PRISM and AVNIR-2. SNR of PRISM image has been increased following the up dating of radiometric correction and implementation of JPEG noise reduction filter. The result was in range of specification for both sensors.

  9. Petrology of blueschist from the Western Himalaya (Ladakh, NW India): Exploring the complex behavior of a lawsonite-bearing system in a paleo-accretionary setting

    NASA Astrophysics Data System (ADS)

    Groppo, Chiara; Rolfo, Franco; Sachan, Himanshu K.; Rai, Santosh K.

    2016-05-01

    Although the Himalaya is the archetype of collisional orogens, formed as a consequence of the closure of the Neo-Tethyan ocean separating India from Asia, high-pressure metamorphic rocks are rare. Beside few eclogites, corresponding to the metamorphosed continental Indian crust dragged below Asia or underthrusted beneath southern Tibet, blueschists occur seldom along the Yarlung-Tsangpo Suture zone, i.e. the suture marking the India-Asia collision. These blueschists, mostly interpreted as related to paleo-accretionary prisms formed in response to the subduction of the Neo-Tethyan ocean below the Asian plate, are crucial for constraining the evolution of the India-Asia convergence zone during the closure of the Neo-Tethyan Ocean. In the Western Himalaya, the best occurrence of blueschist is that of the Sapi-Shergol Ophiolitic Mélange in Ladakh. This unit is dominated by volcanoclastic sequences rich in mafic material with subordinate interbedding of metasediments, characterized by very fresh lawsonite blueschist-facies assemblages. In this paper, the lawsonite blueschist-facies metasediments have been petrologically investigated with the aims of (i) constraining the P-T evolution of the Sapi-Shergol Ophiolitic Mélange, (ii) evaluating the influence of Fe2O3 and of H2O on the stability of the high-pressure mineral assemblages, (iii) understanding the processes controlling lawsonite formation and preservation, and (iv) interpreting the P-T evolution of the Sapi-Shergol blueschists in the framework of India-Asia collision. Our results indicate that (i) the Sapi-Shergol blueschists experienced a cold subduction history along a low thermal gradient, up to peak conditions of ca. 470 °C, 19 kbar; furthermore, in order to preserve lawsonite in the studied lithologies, exhumation must have been coupled with significant cooling, i.e. the resulting P-T path is characterized by a clockwise hairpin loop along low thermal gradients (< 8-9 °C/km); (ii) the presence of ferric

  10. Texture development in naturally compacted and experimentally deformed silty clay sediments from the Nankai Trench and Forearc, Japan

    NASA Astrophysics Data System (ADS)

    Schumann, Kai; Stipp, Michael; Leiss, Bernd; Behrmann, Jan H.

    2014-12-01

    The petrophysical properties of fine-grained marine sediments to a large extent depend on the microstructure and crystallographic preferred orientations (CPOs). In this contribution we show that Rietveld-based synchrotron texture analysis is a new and valuable tool to quantify textures of water-saturated fine-grained phyllosilicate-rich sediments, and assess the effects of compaction and tectonic deformation. We studied the CPO of compositionally almost homogeneous silty clay drillcore samples from the Nankai Accretionary Prism slope and the incoming Philippine Sea plate, offshore SW Japan. Basal planes of phyllosilicates show bedding-parallel alignment increasing with drillhole depth, thus reflecting progressive burial and compaction. In some samples calcite and albite display a CPO due to crystallographically controlled non-isometric grain shapes, or nannofossil tests. Consolidated-undrained experimental deformation of a suite of thirteen samples from the prism slope shows that the CPOs of phyllosilicate and calcite basal planes develop normal to the experimental shortening axis. There is at least a qualitative relation between CPO intensity and strain magnitude. Scanning electron micrographs show concurrent evolution of preferred orientations of micropores and detrital illite flakes normal to axial shortening. This indicates that the microfabrics are sensitive strain gauges, and contribute to anisotropic physical properties along with the CPO.

  11. Prisms with total internal reflection as solar reflectors

    DOEpatents

    Rabl, Arnulf; Rabl, Veronika

    1978-01-01

    An improved reflective wall for radiant energy collection and concentration devices is provided. The wall is comprised of a plurality of prisms whose frontal faces are adjacent and which reflect the desired radiation by total internal reflection.

  12. NORTHERLY STRETCH OF MILLBURY PORTION; GENERAL VIEW ACROSS CANAL PRISM ...

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

    NORTHERLY STRETCH OF MILLBURY PORTION; GENERAL VIEW ACROSS CANAL PRISM TO TOWPATH BERM (LATER FILL ENCROACHING LEFT) NEAR CENTER OF THIS STRETCH; VIEW TO SOUTHWEST - Blackstone Canal Worcester-Millbury Segment, Eastern bank of Blackstone River, Millbury, Worcester County, MA

  13. 3. ELEVATION. FROM SOUTH WITH CANAL PRISM. Canal Road ...

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

    3. ELEVATION. FROM SOUTH WITH CANAL PRISM. - Canal Road Bridge, Canal Road spanning Delaware Canal Diversion, Locks 22 & 23 in Delaware Canal State Park in Williams Township, Raubsville, Northampton County, PA

  14. Strongly-Refractive One-Dimensional Photonic Crystal Prisms

    NASA Technical Reports Server (NTRS)

    Ting, David Z. (Inventor)

    2004-01-01

    One-dimensional (1D) photonic crystal prisms can separate a beam of polychromatic electromagnetic waves into constituent wavelength components and can utilize unconventional refraction properties for wavelength dispersion over significant portions of an entire photonic band rather than just near the band edges outside the photonic band gaps. Using a ID photonic crystal simplifies the design and fabrication process and allows the use of larger feature sizes. The prism geometry broadens the useful wavelength range, enables better optical transmission, and exhibits angular dependence on wavelength with reduced non-linearity. The properties of the 1 D photonic crystal prism can be tuned by varying design parameters such as incidence angle, exit surface angle, and layer widths. The ID photonic crystal prism can be fabricated in a planar process, and can be used as optical integrated circuit elements.

  15. 5. VIEW NORTHWEST SHOWING AQUEDUCT PRISM. NOTE INTERIOR STONE WORK ...

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

    5. VIEW NORTHWEST SHOWING AQUEDUCT PRISM. NOTE INTERIOR STONE WORK OF THE PARAPET WALL AND REMAINS OF 1920 TIMBER AND CONCRETE FLOORING SYSTEM. - Chesapeake & Ohio Canal, Conococheague Creek Aqueduct, Milepost 99.80, Williamsport, Washington County, MD

  16. Dynamics of a microliquid prism actuated by electrowetting.

    PubMed

    Lee, Duck-Gyu; Park, Jaebum; Bae, Jungmok; Kim, Ho-Young

    2013-01-21

    A microliquid prism is a microchannel filled with two immiscible liquids, whose interface acts as a refractive surface. To steer a light beam that constructs optical images, the interface profile or the contact angle is modulated through electrowetting on a dielectric. Accurate, yet agile actuation of the liquid prism critically depends on the understanding of dynamics of the fluid interface. Here we fabricate liquid prisms, visualize the shape evolution of the interface, and theoretically model its dynamics. By comparing the magnitude of capillary forces to those of viscous, inertial and hydrostatic forces, we find that the meniscus motion within submillimetric channels is dominated by the capillary effect. The theoretical predictions for microscale meniscus dynamics are shown to agree well with the experimental measurements. We then discuss the formation of waves in millimetric liquid prisms, which may significantly limit fast and reliable operation of the optofluidic device. PMID:23165931

  17. Why Is White Light Dispersed by a Prism?

    ERIC Educational Resources Information Center

    Crawford, Frank S.

    1979-01-01

    Presents the answer to a question, which is intended for high school students, about the dispersion of white light by a glass prism. Why the high frequency waves travel slower than the lower frequencies in glass is also presented. (HM)

  18. Wedge Prism for Direction Resolved Speckle Correlation Interferometry

    SciTech Connect

    Pechersky, M.J.

    1999-01-20

    The role of a wedge prism for strain sign determination and enhancing the sensitivity for sub-fringe changes is emphasized. The design and incorporation aspects for in-plane sensitive interferometers have been described in detail. Some experimental results dealing with stress determination by laser annealing and speckle corelation interferometry are presented. The prism can also be applied to produce standardized carrier fringes in spatial phase shifting interferometry.

  19. Wedge prism for direction resolved speckle correlation interferometry

    SciTech Connect

    Vikram, C.S.; Pechersky, M.J.

    1999-10-01

    The role of a wedge prism for strain sign determination and to enhance the sensitivity for subfringe changes is presented. The design and incorporation aspects for in-plane sensitive interferometers are described in detail. Some experimental results dealing with stress determination by laser annealing and speckle correlation interferometry are presented. The prism can also be applied to produce standardized carrier fringes in spatial phase shifting interferometry. {copyright} {ital 1999 Society of Photo-Optical Instrumentation Engineers.}

  20. The initial process of enamel prism arrangement and its relation to the Hunter-Schreger bands in dog teeth.

    PubMed

    Hanaizumi, Yoshinori; Yokota, Rumi; Domon, Takanori; Wakita, Minoru; Kozawa, Yukisige

    2010-01-01

    The three-dimensional architecture of enamel prisms at early stages of enamel formation and its spatial relationship to the Hunter-Schreger bands were examined in canine tooth germs by light and electron microscopy. In serial semithin sections of demineralized tooth germs tangential to the enamel-dentin junction, a straight row of enamel prisms was depicted along the longitudinal tooth axis at the level of the enamel-dentin junction and then their three-dimensional arrangement was reconstructed using computer software. The spatial arrangement of the groups of enamel rods oriented in specific sideward directions was also reconstructed in deep layers of the enamel. Initially, all enamel prisms were parallel to perpendicular toward the enamel-dentin junction, but at 10µm from the enamel-dentin junction, some small specks, or groups of enamel prisms--tilting to the right or the left--emerged as small islands. In each speck of enamel prism, the inclined prisms were uniformly oriented in a sideward direction and gradually expanded their boundary until merging with the neighboring specks inclined in the same direction. Consequently, at 50µm from the enamel-dentin junction, the group of enamel prisms oriented either to the right or the left formed alternately arranged horizontal belt-like zones, corresponding to the parazone or the diazone of the Hunter-Schreger bands. Reversed images of scanning electron-micrographs of the exposed surfaces of the developing enamel revealed round and bulb-like profiles of Tomes' processes at early amelogenesis and its changes into a characteristic structure combined with flat secretory and enclosing nonsecretory faces that dictated the orientation of corresponding enamel prisms. The results suggest that the groups of enamel prisms oriented in sideward directions first appear as small island-like specks near the enamel-dentin junction, which later merge and form alternating horizontal belt-like zones as a consequence of morphological

  1. PRISM: a planned risk information seeking model.

    PubMed

    Kahlor, LeeAnn

    2010-06-01

    Recent attention on health-related information seeking has focused primarily on information seeking within specific health and health risk contexts. This study attempts to shift some of that focus to individual-level variables that may impact health risk information seeking across contexts. To locate these variables, the researcher posits an integrated model, the Planned Risk Information Seeking Model (PRISM). The model, which treats risk information seeking as a deliberate (planned) behavior, maps variables found in the Theory of Planned Behavior (TPB; Ajzen, 1991) and the Risk Information Seeking and Processing Model (RISP; Griffin, Dunwoody, & Neuwirth, 1999), and posits linkages among those variables. This effort is further informed by Kahlor's (2007) Augmented RISP, the Theory of Motivated Information Management (Afifi & Weiner, 2004), the Comprehensive Model of Information Seeking (Johnson & Meischke, 1993), the Health Information Acquisition Model (Freimuth, Stein, & Kean, 1989), and the Extended Parallel Processing Model (Witte, 1998). The resulting integrated model accounted for 59% of the variance in health risk information-seeking intent and performed better than the TPB or the RISP alone. PMID:20512716

  2. The Prism Multi-Object Survey (PRIMUS)

    NASA Astrophysics Data System (ADS)

    Wong, K.; Blanton, M.; Burles, S.; Coil, A.; Cool, R.; Eisenstein, D.; Moustakas, J.; Rujopakarn, W.; Zhu, G.

    2010-06-01

    The Prism Multi-Object Survey (PRIMUS) is a galaxy redshift survey covering ˜10 square degrees to a flux limit of i ˜ 23 mag. We acquire roughly 200,000 spectra of galaxies out to z ˜ 1 in fields with existing multiwavelength data in the UV, X-ray, and infrared. By mutiplexing in the wavelength direction, we sacrifice spectral resolution for throughput, allowing us to observe ˜3000 objects per mask for 121 masks over just 39 dark nights at Magellan. Our goal is to combine our redshifts with the existing data to study various aspects of galaxy evolution with redshift, such as star formation rates, stellar mass, luminosity functions, and clustering properties. One of the initial science projects will be to use UV data from the Galaxy Evolution Explorer (GALEX) to derive specific star formation rates for close galaxy pairs (projected separation ≤ 50 h-1 kpc) and compare the enhancement of UV luminosity to isolated galaxies in the field. We will use our redshifts to identify interlopers that are close in projected separation but separated in redshift space to improve the quality of our sample.

  3. Optical materials for near infrared Wollaston prisms

    NASA Astrophysics Data System (ADS)

    Oliva, E.; Gennari, S.; Vanzi, L.; Caruso, A.; Ciofini, M.

    1997-05-01

    The optical characteristics of birefringent materials transmitting in the near IR (0.9-2.5 microns) are analyzed. Wollaston prisms with large beam separation and virtually free from lateral chromatism -- e.g. with fields of view $>1$ arcmin and image elongation ! 3 cm^{-1}) beyond 2.25 microns. The absorption does not decrease significantly when the crystals is cooled, CaCO_3 should not be therefore used in instruments working beyond 2.0 microns.

  4. Negative Refraction experiments in Photonic Crystal prisms

    NASA Astrophysics Data System (ADS)

    Vodo, Plarenta; Parimi, Patanjali. V.; Lu, Wentao. T.; di Gennaro, Emiliano; Sridhar, Srinivas

    2004-03-01

    We have experimentally demonstrated negative refraction in metallic photonic crystal (PC) prisms [1]. The refracted fields in the parallel plate waveguide (PPW) are measured by an automated dipole antenna, which scans the desired area, while the free space (FS) measurements, performed in a anechoic chamber, are measured by a rectangular X-band horn that swings in an arc in far field area. Both TE and TM excitation modes are used in FS experiments. Numerical calculations of the band structure and equi-frequency surface simulations are used to determine frequency regions of negative refraction of the triangular lattice PC. Angle of refraction determined by theoretical simulations and experimental results, are in exceptional good agreement, yielding the negative refraction index. FS and PPW refraction experimental results agree remarkably with simulations. 1. "Negative Refraction and Left-handed electromagnetism in Microwave Photonic Crystals", P.V Parimi, W.T Lu, P.Vodo J. Sokoloff and S.Sridhar, cond-mat/0306109 (2003)

  5. Crustal and Fault Strengths from Critical Taper Measurements: Insights into the behavior of Accretionary Wedges using Distinct-Element Models

    NASA Astrophysics Data System (ADS)

    Strayer, L.; Suppe, J.

    2012-12-01

    It is increasingly clear that many major faults are weak relative to quasistatic friction because of dynamical effects involving the microprocesses of high-velocity friction and the energetics of large-scale fault rupture. Even at the toes of accretionary wedges where velocity strengthening is expected, large displacements can occur dynamically. We seek to better understand the relationship between the large-scale strength of such faults and of the crust containing them over a timescale much greater than seismic cycles. Critical-taper theory provides straightforward quantitative relationships between accretionary wedge geometry and absolute basal fault and wedge strengths with minimal assumptions. Wedge tapers constrain the far-field stresses under which detachments slip and wedges grow during wedge-growing events, whether they are dynamical or quasistatic. To date most applications of wedge mechanics to accretionary wedges involve analog and numerical modeling with largely conceptual insight, for example illuminating the role of geological heterogeneity. Here we demonstrate that recent theoretical advances that are successful in extracting absolute wedge and detachment strengths from the geometry of active wedges can also be applied to extract large-scale strengths in distinct element numerical models in both mechanically homogeneous and heterogeneous wedges. The distinct element method (DEM) is an ideal tool for the study and modeling of critical taper wedges: model wedges can be initially cohesive (bonded) or cohesionless. Faults and folds form naturally as the result of progressive bond breakage during shortening and wedge growth. Heterogeneity can be introduced by creating layered groups of particles of differing mechanical properties. The DEM suffers to some extent in that macro material properties cannot be directly prescribed but rather must be defined by a modest number of micro-properties and the process in necessarily iterative and developing a wide

  6. Hollow optical-fiber based infrared spectroscopy for measurement of blood glucose level by using multi-reflection prism

    PubMed Central

    Kino, Saiko; Omori, Suguru; Katagiri, Takashi; Matsuura, Yuji

    2016-01-01

    A mid-infrared attenuated total reflection (ATR) spectroscopy system employing hollow optical fibers and a trapezoidal multi-reflection ATR prism has been developed to measure blood glucose levels. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. An analysis of in vivo measurements of human inner lip mucosa revealed clear signatures of glucose in the difference spectra between ones taken during the fasting state and ones taken after ingestion of glucose solutions. A calibration plot based on the absorption peak at 1155 cm−1 that originates from the pyranose ring structure of glucose gave measurement errors less than 20%. PMID:26977373

  7. Hollow optical-fiber based infrared spectroscopy for measurement of blood glucose level by using multi-reflection prism.

    PubMed

    Kino, Saiko; Omori, Suguru; Katagiri, Takashi; Matsuura, Yuji

    2016-02-01

    A mid-infrared attenuated total reflection (ATR) spectroscopy system employing hollow optical fibers and a trapezoidal multi-reflection ATR prism has been developed to measure blood glucose levels. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. An analysis of in vivo measurements of human inner lip mucosa revealed clear signatures of glucose in the difference spectra between ones taken during the fasting state and ones taken after ingestion of glucose solutions. A calibration plot based on the absorption peak at 1155 cm(-1) that originates from the pyranose ring structure of glucose gave measurement errors less than 20%. PMID:26977373

  8. Blood glucose measurement in vivo using hollow-fiber based, mid-infrared ATR probe with multi-reflection prism

    NASA Astrophysics Data System (ADS)

    Kino, Saiko; Omori, Suguru; Matsuura, Yuji

    2016-03-01

    An attenuated-total-reflection (ATR), mid-infrared spectroscopy system that consists of hollow optical fibers, a trapezoidal multi-reflection ATR prism, and a conventional FT-IR spectrometer has been developed to measure blood glucose levels. Owing to the low transmission loss and high flexibility of the hollow-optical fiber, the system can measure any sites of the human body where blood capillaries are close to the surface of mucosa, such as inner lips. Using a multi-reflection prism brought about higher sensitivity, and the flat and wide contact surface of the prism resulted in higher measurement reproducibility. The results of in-vivo measurement of human inner lips showed the feasibility of the proposed system, and the measurement errors were within 20%.

  9. Coseismic Strengthening of the Shallow Portion of the Subduction Fault and Effects on Frontal Prism Taper

    NASA Astrophysics Data System (ADS)

    Hu, Y.; Wang, K.; He, J.

    2007-12-01

    state of failure. With a much higher degree of strengthening, the rupture will propagate into the shallow segment only slightly, causing localized compression in the area of slip termination. This may explain the formation of an outer ridge between the outer and inner wedges at some subduction zones. Model results also indicate that for the same force drop, an updip segment with narrower downdip width will require a higher degree of strengthening to prevent trench-breaking rupture. We measured the taper of frontal prisms at 24 subduction zones, and found that the surface slope is generally too high to be explained using the classical Coulomb wedge model but can be explained using the dynamic Coulomb wedge model including coseismic strengthening of the shallow portion of the megathrust. Wang, K., and Y. Hu (2006), Accretionary prisms in subduction earthquake cycles: The theory of dynamic Coulomb wedge, J. Geophys. Res., 111, doi:10.1029/2005JB004094.

  10. Do dissociated or associated phoria predict the comfortable prism?

    PubMed Central

    Otto, Joanna M. N.; Kromeier, Miriam; Bach, Michael

    2008-01-01

    Background Dissociated and associated phoria are measures of latent strabismus under artificial viewing conditions. We examined to what extent dissociated and associated phoria predict the “comfortable prism”, i.e. the prism that appears most comfortable under natural viewing conditions. Methods For associated phoria, a configuration resembling the Mallett test was employed: both eyes were presented with a fixation cross, surrounded by fusionable objects. Nonius lines served as monocular markers. For dissociated phoria, the left eye was presented with all the Mallett elements, while only a white spot was presented to the right eye. To determine the comfortable prism, all the Mallett elements, including the Nonius lines, were shown to both eyes. In each of the three tests, the observer had to adjust a pair of counterrotating prisms. To avoid any (possibly prejudiced) influence of the experimenter, the prismatic power was recorded with a potentiometer. Twenty non-strabismic subjects with a visual acuity of ≥1.0 in each eye were examined. Results The range of the intertrial mean was for dissociated phoria from +9.3 eso to −5.9 cm/m exo, for associated phoria from +11.2 eso to −3.3 cm/m exo, and for the comfortable prism from +4.8 eso to −4.1 cm/m exo (cm/m = prism dioptre). In most observers, the phoria parameters differed greatly from the comfortable prism. On average, the phoria values were shifted about 2 cm/m towards the eso direction in relation to the comfortable prism (associated phoria not less than dissociated phoria). Conclusions The deviation of both, dissociated and associated phoria, from the comfortable prism suggests that the abnormal viewing conditions under which the phoria parameters are determined induce artefacts. Accordingly, the findings cast doubt on current textbook recommendations to use dissociated or associated phoria as a basis for therapeutic prisms. Rather, patients should be allowed to determine their comfortable prism

  11. Splay Faults and Associated Mass Transport Deposits in the Manila Accretionary Wedge near Taiwan: Implications for Geohazards

    NASA Astrophysics Data System (ADS)

    Lin, A. T.; Liu, C. S.; Dirgantara, F.

    2015-12-01

    Plate interface megathrusts are major seismogenic faults in subduction zone, capable of generating great earthquakes with widespread submarine landslides and damaging tsunami. Upward branching of megathrusts results in splay faults in the accretionary wedge. Reflection seismic data across the accretionary wedge off southern Taiwan, reveal at least two strands of splay faults as well as multiple stacked mass transport deposits (MTDs) nearby the faults. With the help of sediment coring and age datings in the vicinity of the splay fault, implications for temporal evolution of the mass wasting processes and episodic activities of splay faults are discussed in this paper. Seismic data show two branches of arcward and gently-dipping splay faults with two slope basins lying in the footwall and hangingwall of the faults, respectively. The older and buried splay fault is inactive as the fault tip is covered by up to 1000 m thick sediments in the footwall slope basin, indicating that it ceased to be active around 0.5 Ma ago. Repeated slip of this fault prior to ~0.5 Ma ago may also result in 4 stacked and multiple mass transport deposits (MTDs) of up to 700-m thick found in vicinity of this fault. This fossil splay fault is characterized by reflection polarity similar to that of seafloor, indicative of low water saturation along the fault zone and hence not an active fluid conduit. The younger and overlying splay fault cuts through the seafloor and the emergent fault tip lying at the toe of steep slope (~ 15 degree) with significant slope break. There is also a 500-m horizontal offset, between the buried paleo-seafloor in the footwall and the present-day seafloor on the hangingwall. The reflection polarity of this fault zone is reversed to that of seafloor, indicating fluid rich for this fault patch. These lines of evidence suggest that this young splay fault is an active fault with active fluid circulation along the fault. Our results indicate that the old splay fault

  12. Application of slip-line analysis to the mechanical model of active accretionary wedge

    NASA Astrophysics Data System (ADS)

    Song, I.; Lee, H.; Kim, J.

    2012-04-01

    An active accretionary wedge is formed from sediments accreted continuously at a continental margin by a subducting plate and mechanically characterized by a plane-strain compressive frictional flow throughout its entire volume. Continuous deformation induced by incoming sediments raises the distortional stress eventually leading to an ultimate condition known as a critical state. According to the critical taper theory (Davis et al., JGR, 1983), the angle of wedge increases as the incoming materials are accreted into the wedge until it reaches a critical value where the shear force on the basal detachment is in equilibrium with the basal friction. Under this concept, we applied the plastic slip-line theory for the computation of stress and velocity fields throughout the continuously deforming area of the wedge. For the simplicity, we assumed that the tapered wedge overlying a basal décollement fault is described by a perfectly plastic rheology complying with the Coulomb failure criterion and the associated flow rule. A complete description of soil rheology at the critical state requires the determination of stress tensors and velocity vectors at given points within the deforming region. For the boundary condition of stress, the effective normal and shear tractions on the upper surface of wedge are equal to zero, and thus the maximum principal stress acts parallel to the surface. Considering the two-dimensional plane strain deformation, we numerically obtained the slip-line solution for the mean effective stress with respect to the orientation of the maximum principal stress at each intersection point of the potential (conjugate) slip lines given by the Coulomb criterion. Then the maximum shear stress was calculated using the failure criterion. After the stress solution was yielded, the velocity field was determined by the same procedure using the boundary condition of the velocity of incoming sediments obtained from the velocity of subducting plate. Our result

  13. Prism-based single-camera system for stereo display

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Cui, Xiaoyu; Wang, Zhiguo; Chen, Hongsheng; Fan, Heyu; Wu, Teresa

    2016-06-01

    This paper combines the prism and single camera and puts forward a method of stereo imaging with low cost. First of all, according to the principle of geometrical optics, we can deduce the relationship between the prism single-camera system and dual-camera system, and according to the principle of binocular vision we can deduce the relationship between binoculars and dual camera. Thus we can establish the relationship between the prism single-camera system and binoculars and get the positional relation of prism, camera, and object with the best effect of stereo display. Finally, using the active shutter stereo glasses of NVIDIA Company, we can realize the three-dimensional (3-D) display of the object. The experimental results show that the proposed approach can make use of the prism single-camera system to simulate the various observation manners of eyes. The stereo imaging system, which is designed by the method proposed by this paper, can restore the 3-D shape of the object being photographed factually.

  14. The Program for Regional and International Shorebird Monitoring (PRISM)

    USGS Publications Warehouse

    Bart, J.; Andres, B.; Brown, S.; Donaldson, G.; Harrington, B.; Johnston, V.; Jones, S.; Morrison, R.I.G.; Skagen, S.K.

    2005-01-01

    This report describes the a??Program for Regional and International Shorebird Monitoringa?? (PRISM). PRISM is being implemented by a Canada-United States Shorebird Monitoring and Assessment Committee formed in 2001 by the Canadian Shorebird Working Group and the U.S. Shorebird Council. PRISM provides a single blueprint for implementing the shorebird conservation plans recently completed in Canada and the United States. The goals of PRISM are to (1) estimate the size of breeding population of 74 shorebird taxa in North America; (2) describe the distribution, abundance, and habitat relationships for each of these taxa; (3) monitor trends in shorebird population size; (4) monitor shorebird numbers at stopover locations, and; (5) assist local managers in meeting their shorebird conservation goals. PRISM has four main components: arctic and boreal breeding surveys, temperate breeding surveys, temperate non-breeding surveys, and neotropical surveys. Progress on, and action items for, each major component are described. The more important major tasks for immediate action are carrying out the northern surveys, conducting regional analyses to design the program of migration counts, and evaluating aerial photographic surveys for migration and winter counts.

  15. Genomes to natural products PRediction Informatics for Secondary Metabolomes (PRISM).

    PubMed

    Skinnider, Michael A; Dejong, Chris A; Rees, Philip N; Johnston, Chad W; Li, Haoxin; Webster, Andrew L H; Wyatt, Morgan A; Magarvey, Nathan A

    2015-11-16

    Microbial natural products are an invaluable source of evolved bioactive small molecules and pharmaceutical agents. Next-generation and metagenomic sequencing indicates untapped genomic potential, yet high rediscovery rates of known metabolites increasingly frustrate conventional natural product screening programs. New methods to connect biosynthetic gene clusters to novel chemical scaffolds are therefore critical to enable the targeted discovery of genetically encoded natural products. Here, we present PRISM, a computational resource for the identification of biosynthetic gene clusters, prediction of genetically encoded nonribosomal peptides and type I and II polyketides, and bio- and cheminformatic dereplication of known natural products. PRISM implements novel algorithms which render it uniquely capable of predicting type II polyketides, deoxygenated sugars, and starter units, making it a comprehensive genome-guided chemical structure prediction engine. A library of 57 tailoring reactions is leveraged for combinatorial scaffold library generation when multiple potential substrates are consistent with biosynthetic logic. We compare the accuracy of PRISM to existing genomic analysis platforms. PRISM is an open-source, user-friendly web application available at http://magarveylab.ca/prism/. PMID:26442528

  16. Genomes to natural products PRediction Informatics for Secondary Metabolomes (PRISM)

    PubMed Central

    Skinnider, Michael A.; Dejong, Chris A.; Rees, Philip N.; Johnston, Chad W.; Li, Haoxin; Webster, Andrew L. H.; Wyatt, Morgan A.; Magarvey, Nathan A.

    2015-01-01

    Microbial natural products are an invaluable source of evolved bioactive small molecules and pharmaceutical agents. Next-generation and metagenomic sequencing indicates untapped genomic potential, yet high rediscovery rates of known metabolites increasingly frustrate conventional natural product screening programs. New methods to connect biosynthetic gene clusters to novel chemical scaffolds are therefore critical to enable the targeted discovery of genetically encoded natural products. Here, we present PRISM, a computational resource for the identification of biosynthetic gene clusters, prediction of genetically encoded nonribosomal peptides and type I and II polyketides, and bio- and cheminformatic dereplication of known natural products. PRISM implements novel algorithms which render it uniquely capable of predicting type II polyketides, deoxygenated sugars, and starter units, making it a comprehensive genome-guided chemical structure prediction engine. A library of 57 tailoring reactions is leveraged for combinatorial scaffold library generation when multiple potential substrates are consistent with biosynthetic logic. We compare the accuracy of PRISM to existing genomic analysis platforms. PRISM is an open-source, user-friendly web application available at http://magarveylab.ca/prism/. PMID:26442528

  17. Prism adaptation changes the subjective proprioceptive localization of the hands.

    PubMed

    Scarpina, Federica; Van der Stigchel, Stefan; Nijboer, Tanja Cornelia Wilhelmina; Dijkerman, Hendrik Christiaan

    2015-03-01

    Prism adaptation involves a proprioceptive, a visual and a motor component. As the existing paradigms are not able to distinguish between these three components, the contribution of the proprioceptive component remains unclear. In the current study, a proprioceptive judgement task, in the absence of motor responses, was used to investigate how prism adaptation would specifically influences the felt position of the hands in healthy participants. The task was administered before and after adaptation to left and right displacing prisms using either the left or the right hand during the adaptation procedure. The results appeared to suggest that the prisms induced a drift in the felt position of the hands, although the after-effect depended on the combination of the pointing hand and the visual deviation induced by prisms. The results are interpreted as in line with the hypothesis of an asymmetrical neural architecture of somatosensory processing. Moreover, the passive proprioception of the hand position revealed different effects of proprioceptive re-alignment compared to active pointing straight ahead: different mechanisms about how visuo-proprioceptive discrepancy is resolved were hypothesized. PMID:24266883

  18. An angular fluidic channel for prism-free surface-plasmon-assisted fluorescence capturing

    NASA Astrophysics Data System (ADS)

    Nomura, Ken-Ichi; Gopinath, Subash C. B.; Lakshmipriya, Thangavel; Fukuda, Nobuko; Wang, Xiaomin; Fujimaki, Makoto

    2013-12-01

    Surface plasmon excitation provides stronger enhancement of the fluorescence intensity and better sensitivity than other sensing approaches but requires optimal positioning of a prism to ensure optimum output of the incident light. Here we describe a simple, highly sensitive optical sensing system combining surface plasmon excitation and fluorescence to address this limitation. V-shaped fluidic channels are employed to mimic the functions of a prism, sensing plate, and flow channel in a single setup. Superior performance is demonstrated for different biomolecular recognition reactions on a self-assembled monolayer, and the sensitivity reaches 100 fM for biotin-streptavidin interactions. Using an antibody as a probe, we demonstrate the detection of intact influenza viruses at 0.2 HA units ml-1 levels. The convenient sensing system developed here has the advantages of being prism-free and requiring less sample (1-2 μl), making this platform suitable for use in situations requiring low sample volumes.

  19. PRISM: A DATA-DRIVEN PLATFORM FOR MONITORING MENTAL HEALTH.

    PubMed

    Kamdar, Maulik R; Wu, Michelle J

    2016-01-01

    Neuropsychiatric disorders are the leading cause of disability worldwide and there is no gold standard currently available for the measurement of mental health. This issue is exacerbated by the fact that the information physicians use to diagnose these disorders is episodic and often subjective. Current methods to monitor mental health involve the use of subjective DSM-5 guidelines, and advances in EEG and video monitoring technologies have not been widely adopted due to invasiveness and inconvenience. Wearable technologies have surfaced as a ubiquitous and unobtrusive method for providing continuous, quantitative data about a patient. Here, we introduce PRISM-Passive, Real-time Information for Sensing Mental Health. This platform integrates motion, light and heart rate data from a smart watch application with user interactions and text entries from a web application. We have demonstrated a proof of concept by collecting preliminary data through a pilot study of 13 subjects. We have engineered appropriate features and applied both unsupervised and supervised learning to develop models that are predictive of user-reported ratings of their emotional state, demonstrating that the data has the potential to be useful for evaluating mental health. This platform could allow patients and clinicians to leverage continuous streams of passive data for early and accurate diagnosis as well as constant monitoring of patients suffering from mental disorders. PMID:26776198

  20. PRISM: A Practical Mealtime Imaging Stereo Matcher

    NASA Astrophysics Data System (ADS)

    Nishihara, H. K.

    1984-02-01

    A fast stereo-matching algorithm designed to operate in the presence of noise is described. The algorithm has its roots in the zero-crossing theory of Marr and Poggio but does not explicitly match zero-crossing contours. While these contours are for the most part stably tied to fixed surface locations, some fraction is always perturbed significantly by system noise. Zero-crossing contour based matching algorithms tend to I- very sensitive to these local distortions and ar, prevented from operating well on signals with moderate noise levels even though a substantial amount of information may still be present. The dual representation ¬â€?regions of constant sign in the V2G convolution persist much further into the noise than does the local geometry of the zero-crossing contours that delimit them. The PRISM system was designed to test this approach. The initial design task of the implementation has been to rapidly detect obstacles in a robotics work space and determine their rough extents and heights. In this case speed and reliability are important but precision is less critical. The system uses a pair of inexpensive vidicon cameras mounted above the workspace of a PUMA robot manipulator. The digitized video signals are fed to a high speed digital convolver that applies a 322 VG operator to the images at a 106 pixel per second rate. Matching is accomplished in software on a lisp machine with individual near/far tests taking less than i3luth of a second. A 36 by 26 matrix of absolute height measurements - in mm - over a 100 pixel disparity range is produced in 30 seconds from image acquisition to final output. Three scales of resolution are used in a coarse guides fine search. Acknowledgment: This report describes research done at the Artificial Intelligence Laboratory of the Massachusetts Institute of 'Technology Support for the laboratory's artificial intelligence research is provided in part by the Advanced Research Projects Agency of the Department of Defense

  1. Control of structural inheritance on thrust initiation and material transfer in accretionary wedges

    NASA Astrophysics Data System (ADS)

    Leever, Karen; Geersen, Jacob; Ritter, Malte; Lieser, Kathrin; Behrmann, Jan

    2016-04-01

    Faults in the incoming sediment layer are commonly observed in subduction zone settings and well developed in the incoming plate off Sumatra. To investigate how they affect the structural development of the accretionary wedge, we conducted a series of 2D analogue tectonic experiments in which a 2 cm thick quartz sand layer on top of a thin detachment layer of glass beads was pulled against a rigid backstop by a basal conveyor belt in a 20cm wide box with glass walls. A gap at the base of the back wall avoids entrainment of the glass beads. At regular spacing of either 2.3, 5.5 or 7.8 cm (fractions of the thrust sheet length in the reference model), conjugate pairs of weakness zones dipping 60deg were created by cutting the sand layer with a thin (1 mm) metal blade. Both the undisturbed sand and the pre-cuts have an angle of internal friction of ~29o, but their cohesion is different by 50 Pa (110 Pa for the undisturbed material, 60 Pa along the pre-cuts). Friction of the glass beads is ~24deg. The experiments are monitored with high resolution digital cameras; displacement fields derived from digital image correlation are used to constrain fault activity. In all experiments, a critically tapered wedge developed with a surface slope of 7.5deg. In the reference model (no weakness zones in the input section), the position of new thrust faults is controlled by the frontal slope break. The average length of the thrust sheets is 11 cm and the individual thrusts accommodate on average 8 cm displacement each. The presence of weakness zones causes thrust initiation at a position different from the reference case, and affects their dip. For a fault spacing of 7.8 cm (or 75% of the reference thrust sheet length), every single incoming weakness zone causes the formation of a new thrust, thus resulting in thrust sheets shorter than the equilibrium case. In addition, less displacement is accommodated on each thrust. As a consequence, the frontal taper is smaller than expected

  2. Study the sensitivity of dose calculation in prism treatment planning system using Monte Carlo simulation of 6 MeV electron beam

    SciTech Connect

    Hardiansyah, D.; Haryanto, F.; Male, S.

    2014-09-30

    Prism is a non-commercial Radiotherapy Treatment Planning System (RTPS) develop by Ira J. Kalet from Washington University. Inhomogeneity factor is included in Prism TPS dose calculation. The aim of this study is to investigate the sensitivity of dose calculation on Prism using Monte Carlo simulation. Phase space source from head linear accelerator (LINAC) for Monte Carlo simulation is implemented. To achieve this aim, Prism dose calculation is compared with EGSnrc Monte Carlo simulation. Percentage depth dose (PDD) and R50 from both calculations are observed. BEAMnrc is simulated electron transport in LINAC head and produced phase space file. This file is used as DOSXYZnrc input to simulated electron transport in phantom. This study is started with commissioning process in water phantom. Commissioning process is adjusted Monte Carlo simulation with Prism RTPS. Commissioning result is used for study of inhomogeneity phantom. Physical parameters of inhomogeneity phantom that varied in this study are: density, location and thickness of tissue. Commissioning result is shown that optimum energy of Monte Carlo simulation for 6 MeV electron beam is 6.8 MeV. This commissioning is used R50 and PDD with Practical length (R{sub p}) as references. From inhomogeneity study, the average deviation for all case on interest region is below 5 %. Based on ICRU recommendations, Prism has good ability to calculate the radiation dose in inhomogeneity tissue.

  3. Study the sensitivity of dose calculation in prism treatment planning system using Monte Carlo simulation of 6 MeV electron beam

    NASA Astrophysics Data System (ADS)

    Hardiansyah, D.; Male, S.; Haryanto, F.

    2014-09-01

    Prism is a non-commercial Radiotherapy Treatment Planning System (RTPS) develop by Ira J. Kalet from Washington University. Inhomogeneity factor is included in Prism TPS dose calculation. The aim of this study is to investigate the sensitivity of dose calculation on Prism using Monte Carlo simulation. Phase space source from head linear accelerator (LINAC) for Monte Carlo simulation is implemented. To achieve this aim, Prism dose calculation is compared with EGSnrc Monte Carlo simulation. Percentage depth dose (PDD) and R50 from both calculations are observed. BEAMnrc is simulated electron transport in LINAC head and produced phase space file. This file is used as DOSXYZnrc input to simulated electron transport in phantom. This study is started with commissioning process in water phantom. Commissioning process is adjusted Monte Carlo simulation with Prism RTPS. Commissioning result is used for study of inhomogeneity phantom. Physical parameters of inhomogeneity phantom that varied in this study are: density, location and thickness of tissue. Commissioning result is shown that optimum energy of Monte Carlo simulation for 6 MeV electron beam is 6.8 MeV. This commissioning is used R50 and PDD with Practical length (Rp) as references. From inhomogeneity study, the average deviation for all case on interest region is below 5 %. Based on ICRU recommendations, Prism has good ability to calculate the radiation dose in inhomogeneity tissue.

  4. The PRISM4 (mid-Piacenzian) Palaeoenvironmental Reconstruction

    NASA Technical Reports Server (NTRS)

    Dowsett, Harry; Dolan, Aisling; Rowley, David; Moucha, Robert; Forte, Alessandro M.; Mitrovica, Jerry X.; Pound, Matthew; Salzmann, Ulrich; Robinson, Marci; Chandler, Mark; Foley, Kevin; Haywood, Alan

    2016-01-01

    The mid-Piacenzian is known as a period of relative warmth when compared to the present day. A comprehensive understanding of conditions during the Piacenzian serves as both a conceptual model and a source for boundary conditions as well as means of verification of global climate model experiments. In this paper we present the PRISM4 reconstruction, a paleoenvironmental reconstruction of the mid-Piacenzian (approximately 3 Ma) containing data for paleogeography, land and sea ice, sea-surface temperature, vegetation, soils, and lakes. Our retrodicted paleogeography takes into account glacial isostatic adjustments and changes in dynamic topography. Soils and lakes, both significant as land surface features, are introduced to the PRISM reconstruction for the first time. Sea-surface temperature and vegetation reconstructions are unchanged but now have confidence assessments. The PRISM4 reconstruction is being used as boundary condition data for the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2) experiments.

  5. The PRISM4 (mid-Piacenzian) paleoenvironmental reconstruction

    NASA Astrophysics Data System (ADS)

    Dowsett, Harry; Dolan, Aisling; Rowley, David; Moucha, Robert; Forte, Alessandro M.; Mitrovica, Jerry X.; Pound, Matthew; Salzmann, Ulrich; Robinson, Marci; Chandler, Mark; Foley, Kevin; Haywood, Alan

    2016-07-01

    The mid-Piacenzian is known as a period of relative warmth when compared to the present day. A comprehensive understanding of conditions during the Piacenzian serves as both a conceptual model and a source for boundary conditions as well as means of verification of global climate model experiments. In this paper we present the PRISM4 reconstruction, a paleoenvironmental reconstruction of the mid-Piacenzian ( ˜ 3 Ma) containing data for paleogeography, land and sea ice, sea-surface temperature, vegetation, soils, and lakes. Our retrodicted paleogeography takes into account glacial isostatic adjustments and changes in dynamic topography. Soils and lakes, both significant as land surface features, are introduced to the PRISM reconstruction for the first time. Sea-surface temperature and vegetation reconstructions are unchanged but now have confidence assessments. The PRISM4 reconstruction is being used as boundary condition data for the Pliocene Model Intercomparison Project Phase 2 (PlioMIP2) experiments.

  6. Enhanced scanning agility using a double pair of Risley prisms.

    PubMed

    Roy, Gilles; Cao, Xiaoying; Bernier, Robert; Roy, Simon

    2015-12-01

    Scanners with one pair of Risley prisms are robust and precise and they can be operated continuously. In this paper, we present a new scanner based on the use of two pairs of Risley prisms. The concept was driven by the need to add flexibility to Risley prism scanners used for lidar 3D mapping applications, while maintaining compactness and robustness. The first pair covers a FOV narrower than the second pair. The second pair is used to position the first Risley pair scan pattern anywhere within its own, larger, FOV. Doing so, it becomes possible, without additional scanner components, to increase the sampling point density at a specific location, to increase the sampling uniformity of the scanned area, and, while in motion, to maintain the sampling of a specific area of interest. PMID:26836680

  7. Birefringent neutron prisms for spin echo scattering angle measurement

    NASA Astrophysics Data System (ADS)

    Pynn, Roger; Fitzsimmons, M. R.; Lee, W. T.; Stonaha, P.; Shah, V. R.; Washington, A. L.; Kirby, B. J.; Majkrzak, C. F.; Maranville, B. B.

    2009-09-01

    In the first decade of the 19th century, an English chemist, William Wollaston, invented an arrangement of birefringent prisms that splits a beam of light into two spatially separated beams with orthogonal polarizations. We have constructed similar devices for neutrons using triangular cross-section solenoids and employed them for Spin Echo Scattering Angle Measurement (SESAME). A key difference between birefringent neutron prisms and their optical analogues is that it is hard to embed the former in a medium which has absolutely no birefringence because this implies the removal of all magnetic fields. We have overcome this problem by using the symmetry properties of the Wollaston neutron prisms and of the overall spin echo arrangement. These symmetries cause a cancellation of Larmor phase aberrations and provide robust coding of neutron scattering angles with simple equipment.

  8. Quartz-Enhanced Photoacoustic Spectroscopy with Right-Angle Prism

    PubMed Central

    Liu, Yongning; Chang, Jun; Lian, Jie; Liu, Zhaojun; Wang, Qiang; Qin, Zengguang

    2016-01-01

    A right-angle prism was used to enhance the acoustic signal of a quartz-enhanced photoacoustic spectroscopy (QEPAS) system. The incident laser beam was parallelly inverted by the right-angle prism and passed through the gap between two tuning fork prongs again to produce another acoustic excitation. Correspondingly, two pairs of rigid metal tubes were used as acoustic resonators with resonance enhancement factors of 16 and 12, respectively. The QEPAS signal was enhanced by a factor of 22.4 compared with the original signal, which was acquired without resonators or a prism. In addition, the system noise was reduced a little with double resonators due to the Q factor decrease. The signal-to-noise ratio (SNR) was greatly improved. Additionally, a normalized noise equivalent absorption coefficient (NNEA) of 5.8 × 10−8 W·cm−1·Hz−1/2 was achieved for water vapor detection in the atmosphere. PMID:26861344

  9. Advanced hyperspectral video imaging system using Amici prism.

    PubMed

    Feng, Jiao; Fang, Xiaojing; Cao, Xun; Ma, Chenguang; Dai, Qionghai; Zhu, Hongbo; Wang, Yongjin

    2014-08-11

    In this paper, we propose an advanced hyperspectral video imaging system (AHVIS), which consists of an objective lens, an occlusion mask, a relay lens, an Amici prism and two cameras. An RGB camera is used for spatial reading and a gray scale camera is used for measuring the scene with spectral information. The objective lens collects more light energy from the observed scene and images the scene on an occlusion mask, which subsamples the image of the observed scene. Then, the subsampled image is sent to the gray scale camera through the relay lens and the Amici prism. The Amici prism that is used to realize spectral dispersion along the optical path reduces optical distortions and offers direct view of the scene. The main advantages of the proposed system are improved light throughput and less optical distortion. Furthermore, the presented configuration is more compact, robust and practicable. PMID:25321019

  10. Accretion in the wake of terrane collision: The Neogene accretionary wedge off Kenai Peninsula, Alaska

    USGS Publications Warehouse

    Fruehn, J.; Von Huene, R.; Fisher, M.A.

    1999-01-01

    Subduction accretion and repeated terrane collision shaped the Alaskan convergent margin. The Yakutat Terrane is currently colliding with the continental margin below the central Gulf of Alaska. During the Neogene the terrane's western part was subducted after which a sediment wedge accreted along the northeast Aleutian Trench. This wedge incorporates sediment eroded from the continental margin and marine sediments carried into the subduction zone on the Pacific plate. Prestack depth migration was performed on six seismic reflection lines to resolve the structure within this accretionary wedge and its backstop. The lateral extent of the structures is constrained by high-resolution swath bathymetry and seismic lines collected along strike. Accretionary structure consists of variably sized thrust slices that were deformed against a backstop during frontal accretion and underplating. Toward the northeast the lower slope steepens, the wedge narrows, and the accreted volume decreases notwith-standing a doubling of sediments thickness in the trench. In the northeasternmost transect, near the area where the terrane's trailing edge subducts, no frontal accretion is observed and the slope is eroded. The structures imaged along the seismic lines discussed here most likely result from progressive evolution from erosion to accretion, as the trailing edge of the Yakutat Terrane is subducting.

  11. Late Cretaceous to Early Tertiary transtension and strain partitioning in the Chugach accretionary complex, SE Alaska

    NASA Astrophysics Data System (ADS)

    Davis, J. Steven; Roeske, Sarah M.; Karl, Sue M.

    1998-05-01

    Shear zones in the Late Cretaceous Sitka Graywacke of the Chugach accretionary complex in southeast Alaska record constrictional finite strains, with maximum principal stretches plunging shallowly subparallel to strike of the shear zones. Macrostructural analysis indicates the finite strain formed during one deformation event. Microstructural analysis of the shear zones shows that this deformation is ductile, promoted mostly through deformation of low-strength lithic clasts and pressure solution. Kinematic indicators from some of the shear zones indicate dominantly dextral motion. Although multiple scenarios can explain constrictional finite strains in a shear zone, these dextral strike-slip shear zones must have experienced a component of extension across them in order to generate constrictional finite strains. Therefore, the shear zones are dextral transtensional shear zones, an uncommon tectonic regime in an accretionary complex. The transtensional shear zones reflect strike-slip motion related to partitioning of Late Cretaceous to Early Tertiary right-oblique convergence between North America and the Farallon plate. The extensional component that was superposed on the strike-slip shear zones to generate transtension resulted from contemporaneous collapse of the forearc following thickening related to underplating.

  12. Clinical and Laboratory Evaluation of Peripheral Prism Glasses for Hemianopia

    PubMed Central

    Giorgi, Robert G.; Woods, Russell L.; Peli, Eli

    2008-01-01

    Purpose Homonymous hemianopia (the loss of vision on the same side in each eye) impairs the ability to navigate and walk safely. We evaluated peripheral prism glasses as a low vision optical device for hemianopia in an extended wearing trial. Methods Twenty-three patients with complete hemianopia (13 right) with neither visual neglect nor cognitive deficit enrolled in the 5-visit study. To expand the horizontal visual field, patients’ spectacles were fitted with both upper and lower Press-On™ Fresnel prism segments (each 40 prism diopters) across the upper and lower portions of the lens on the hemianopic (“blind”) side. Patients were asked to wear these spectacles as much as possible for the duration of the study, which averaged 9 (range: 5 to 13) weeks. Clinical success (continued wear, indicating perceived overall benefit), visual field expansion, perceived direction and perceived quality of life were measured. Results Clinical Success: 14 of 21 (67%) patients chose to continue to wear the peripheral prism glasses at the end of the study (2 patients did not complete the study for non-vision reasons). At long-term follow-up (8 to 51 months), 5 of 12 (42%) patients reported still wearing the device. Visual Field Expansion: Expansion of about 22 degrees in both the upper and lower quadrants was demonstrated for all patients (binocular perimetry, Goldmann V4e). Perceived Direction: Two patients demonstrated a transient adaptation to the change in visual direction produced by the peripheral prism glasses. Quality of Life: At study end, reduced difficulty noticing obstacles on the hemianopic side was reported. Conclusions The peripheral prism glasses provided reported benefits (usually in obstacle avoidance) to 2/3 of the patients completing the study, a very good success rate for a vision rehabilitation device. Possible reasons for long-term discontinuation and limited adaptation of perceived direction are discussed. PMID:19357552

  13. Assessment of prism responses to loss of flow events

    SciTech Connect

    Slovik, G.C.; Van Tuyle, G.J.; Sands, S.

    1992-09-01

    The Nuclear Regulatory Commission (NRC), with Brookhaven national Laboratory providing technical support, is continuing a preapplication review of the 471 MWt, advanced liquid metal reactor (ALMR), PRISM by General Electric. The revised design has been evaluated using the SSC code, for a series of loss of flow events (LOF) with and without gas expansion modules (GEMs). These devices have a net worth of 69{cents} and have reduced the seriousness of the LOF in PRISM. However, it was found that the extremely low probability case of an instantaneous loss of 4 EM pumps without scram could lead to sodium boiling even with the GEMs.

  14. Imaging of neuronal tissue using a prism adjunct

    NASA Astrophysics Data System (ADS)

    Broadbridge, Philip; Bradu, Adrian; Lall, Gurprit; Podoleanu, Adrian G.

    2014-03-01

    We present the use of a prism as an imaging adjunct with a multimodal system of optical coherence tomography and confocal microscopy operating at 1320 nm and 970 nm respectively. A comparison is performed between en-face OCT images acquired using the system and cross section OCT images obtained through a prism inserted into neuronal tissue of an intact ex-vivo murine brain. The en-face images and cross section images are scans of the same area; however each method has shown different aspects, allowing for greater interpretation of the neuronal tissue.

  15. Beam distortion of rotation double prisms with an arbitrary incident angle.

    PubMed

    Li, Anhu; Zuo, Qiyou; Sun, Wansong; Yi, Wanli

    2016-07-01

    The distortion of beam shape in rotation Risley prisms is discussed in this paper. Using the ray-tracing method based on vector refraction theorem, a rigorous theoretical model of beam distortion with an arbitrary incident angle is established to explore the influencing factors. For a specified double-prism pair, the emergent beam is squeezed in one direction while stretched in the mutual perpendicular direction, the distortion of which is determined by the relative rotation angle. Moreover, the distortion of beam shape is greatly influenced by the wedge angles and the refractive indices of the prisms, as well as different double-prism configurations, while uncorrelated to the prism thickness and the distance between two prisms. This paper demonstrates the regular change of the beam shape with multiparameter variations in rotation double prisms, which can be applied to the design of rotation double-prism systems. PMID:27409205

  16. Generation and emplacement of Triassic granitoids within the Songpan Ganze accretionary-orogenic wedge in a context of slab retreat accommodated by tear faulting, Eastern Tibetan plateau, China

    NASA Astrophysics Data System (ADS)

    de Sigoyer, Julia; Vanderhaeghe, Olivier; Duchêne, Stéphanie; Billerot, Audrey

    2014-07-01

    asthenospheric mantle into the tear fault owing to decompression, (iii) the metasomatized lithospheric continental mantle of the Yangtze craton owing to the temperature increase associated to the asthenospheric upwelling and (iv) the rocks of the Songpan Ganze accretionary wedge composed of metasediments and Yangtze continental margin basement owing to the combined effects of increased radioactive heat production and mantle heat flux. We propose that the concentration of plutons along the eastern margin of the Songpan Ganze results from focussed migration and emplacement of the granitic magmas guided by the development of a tear fault along the former passive eastern margin of the Yangtze craton as a consequence of the Paleotethys slab retreat.

  17. Evidence for tectonic emplacement of ultramafic and associated rocks in the pre-Silurian eugeoclinal belt of western New England- vestiges of an ancient accretionary wedge.

    USGS Publications Warehouse

    Stanley, R.S.; Roy, D.L.; Hatch, N.L., Jr.; Knapp, D.A.

    1984-01-01

    Three ultramafic and associated rocks occur in a highly faulted zone of pre-Silurian metamorphosed rocks, in which serpentinites and talc-carbonate rocks occur as slivers along faults that separate contrasting lithic assemblages. Results of detailed investigation of the map pattern, fault fabrics, lithic assemblages and metamorphism of the ultramafic belt in the Jay area of northern Vermont and comparison with its southern continuation in Massachusetts are cited as evidence supporting interpretation of the ultramafic and associated rocks as imbricated fragments of oceanic crust. Emplacement of the fragments in a stratigraphic sequence that was originally deposited along the continental margin of North America and on adjoining oceanic crust accompanied development of an accretionary wedge associated with an east-dipping subduction zone. (Preceding abstracts)-M.S.

  18. A Pilot Evaluation of On-Road Detection Performance by Drivers with Hemianopia Using Oblique Peripheral Prisms

    PubMed Central

    Bowers, Alex R.; Tant, Mark; Peli, Eli

    2012-01-01

    Aims. Homonymous hemianopia (HH), a severe visual consequence of stroke, causes difficulties in detecting obstacles on the nonseeing (blind) side. We conducted a pilot study to evaluate the effects of oblique peripheral prisms, a novel development in optical treatments for HH, on detection of unexpected hazards when driving. Methods. Twelve people with complete HH (median 49 years, range 29–68) completed road tests with sham oblique prism glasses (SP) and real oblique prism glasses (RP). A masked evaluator rated driving performance along the 25 km routes on busy streets in Ghent, Belgium. Results. The proportion of satisfactory responses to unexpected hazards on the blind side was higher in the RP than the SP drive (80% versus 30%; P = 0.001), but similar for unexpected hazards on the seeing side. Conclusions. These pilot data suggest that oblique peripheral prisms may improve responses of people with HH to blindside hazards when driving and provide the basis for a future, larger-sample clinical trial. Testing responses to unexpected hazards in areas of heavy vehicle and pedestrian traffic appears promising as a real-world outcome measure for future evaluations of HH rehabilitation interventions aimed at improving detection when driving. PMID:23316415

  19. 49 CFR 390.203 - PRISM State registration/biennial updates.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 5 2014-10-01 2014-10-01 false PRISM State registration/biennial updates. 390.203... FEDERAL MOTOR CARRIER SAFETY REGULATIONS; GENERAL Unified Registration System § 390.203 PRISM State... the Performance and Registration Information Systems Management (PRISM) program (authorized...

  20. 49 CFR 390.203 - PRISM State registration/biennial updates.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 5 2013-10-01 2013-10-01 false PRISM State registration/biennial updates. 390.203... FEDERAL MOTOR CARRIER SAFETY REGULATIONS; GENERAL Unified Registration System § 390.203 PRISM State... the Performance and Registration Information Systems Management (PRISM) program (authorized...

  1. Coherent coupling of independent grating-surface-emitting diode laser arrays using an external prism

    SciTech Connect

    Carlson, N.W.; Evans, G.A.; Lurie, M.; Hammer, J.M.; Kaiser, C.J.; Liew, S.K. )

    1990-01-08

    Pairs of grating surface-emitting arrays, on a single wafer but free-running, were externally coupled with a prism. The prism acted as an optical coupler between one distributed Bragg reflector in each array. Injection locking was demonstrated by observing a dramatic increase in the lateral coherence of the far field of the prism-coupled arrays.

  2. Accretionary lapilli, tektites, or concretions: the ubiquitous spherules of Meridiani Planum

    NASA Astrophysics Data System (ADS)

    DiGregorio, Barry E.

    2004-11-01

    One of the most enigmatic discoveries made by the NASA Mars Exploration Rover Opportunity (MER-B) at the Meridiani Planum landing site are the ubiquitous spherules referred to as "blueberries" by the science team. They cover the entire landing area and can be seen in every direction within view of the rover cameras. Subsequent analysis of a small grouping of the spherules laying on top of a rock outcrop by Mossbauer spectroscopy showed an intense hematite signature not found on the rock or in the surrounding basaltic soils. Spherules were also found attached to and embedded within sedimentary sulfate rock outcrops found at the landing area that have been determined by the MER science team as having been formed in an acidic liquid water environment. The appearance of most of the Meridiani spherules is strikingly similar to the morphology and size of terrestrial accretionary lapilli and show similarities to terrestrial tektites. Accretionary lapilli are spherical balls and fragments with a concentric layered structure that are formed by a variety of mechanisms including hydrovolcanic eruptions, geysers and large meteorite impacts in water. Tektites are glassy impact spherules that form as a result of large meteorite impacts and also seem apparent in some of the rover images. Tektites can be perfectly spherical or have teardrop and dumbbell shapes. A lack of a visible volcanic source capable of producing high volumes of accretionary lapilli as seen in the MER-B images, in combination with the strong spectral signature of hematite, that some of the spherules display, led the MER science team to favor a concretion hypothesis thus far. All of these types of spherules involve interaction of with surface water or ice to form. Problems exist in explaining how the Martian "concretions", if that is indeed what they are, are of such uniform size and have such a wide distribution. Evidence from Martian orbit and on the surface indicate that the Meridiani Planum landing ellipse

  3. Episodic fluid flow in the Nankai accretionary complex: Timescale, geochemistry, flow rates, and fluid budget

    USGS Publications Warehouse

    Saffer, D.M.; Bekins, B.A.

    1998-01-01

    Down-hole geochemical anomalies encountered in active accretionary systems can be used to constrain the timing, rates, and localization of fluid flow. Here we combine a coupled flow and solute transport model with a kinetic model for smectite dehydration to better understand and quantify fluid flow in the Nankai accretionary complex offshore of Japan. Compaction of sediments and clay dehydration provide fluid sources which drive the model flow system. We explicitly include the consolidation rate of underthrust sediments in our calculations to evaluate the impact that variations in this unknown quantity have on pressure and chloride distribution. Sensitivity analysis of steady state pressure solutions constrains bulk and flow conduit permeabilities. Steady state simulations with 30% smectite in the incoming sedimentary sequence result in minimum chloride concentrations at site 808 of 550 mM, but measured chlorinity is as low as 447 mM. We simulate the transient effects of hydrofracture or a strain event by assuming an instantaneous permeability increase of 3-4 orders of magnitude along a flow conduit (in this case the de??collement), using steady state results as initial conditions. Transient results with an increase in de??collement permeability from 10-16 m2 to 10-13 m2 and 20% smectite reproduce the observed chloride profile at site 808 after 80-160 kyr. Modeled chloride concentrations are highly sensitive to the consolidation rate of underthrust sediments, such that rapid compaction of underthrust material leads to increased freshening. Pressures within the de??collement during transient simulations rise rapidly to a significant fraction of lithostatic and remain high for at least 160 kyr, providing a mechanism for maintaining high permeability. Flow rates at the deformation front for transient simulations are in good agreement with direct measurements, but steady state flow rates are 2-3 orders of magnitude smaller than observed. Fluid budget calculations

  4. Experimental volcanic ash aggregation: Internal structuring of accretionary lapilli and the role of liquid bonding

    NASA Astrophysics Data System (ADS)

    Mueller, Sebastian B.; Kueppers, Ulrich; Ayris, Paul M.; Jacob, Michael; Dingwell, Donald B.

    2016-01-01

    Explosive volcanic eruptions can release vast quantities of pyroclastic material into Earth's atmosphere, including volcanic ash, particles with diameters less than two millimeters. Ash particles can cluster together to form aggregates, in some cases reaching up to several centimeters in size. Aggregation alters ash transport and settling behavior compared to un-aggregated particles, influencing ash distribution and deposit stratigraphy. Accretionary lapilli, the most commonly preserved type of aggregates within the geologic record, can exhibit complex internal stratigraphy. The processes involved in the formation and preservation of these aggregates remain poorly constrained quantitatively. In this study, we simulate the variable gas-particle flow conditions which may be encountered within eruption plumes and pyroclastic density currents via laboratory experiments using the ProCell Lab System® of Glatt Ingenieurtechnik GmbH. In this apparatus, solid particles are set into motion in a fluidized bed over a range of well-controlled boundary conditions (particle concentration, air flow rate, gas temperature, humidity, liquid composition). Experiments were conducted with soda-lime glass beads and natural volcanic ash particles under a range of experimental conditions. Both glass beads and volcanic ash exhibited the capacity for aggregation, but stable aggregates could only be produced when materials were coated with high but volcanically-relevant concentrations of NaCl. The growth and structure of aggregates was dependent on the initial granulometry, while the rate of aggregate formation increased exponentially with increasing relative humidity (12-45% RH), before overwetting promoted mud droplet formation. Notably, by use of a broad granulometry, we generated spherical, internally structured aggregates similar to some accretionary pellets found in volcanic deposits. Adaptation of a powder-technology model offers an explanation for the origin of natural accretionary

  5. 4. VIEW SOUTH SHOWING AQUEDUCT PRISM. NOTE 1920 TIMBER AND ...

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

    4. VIEW SOUTH SHOWING AQUEDUCT PRISM. NOTE 1920 TIMBER AND CONCRETE FLOORING SYSTEM, POCKETS FOR VERTICAL POSTS AND BRIDGING, STEEL BRACES ADDED BY THE NATIONAL PARK SERVICE CIRCA 1962. - Chesapeake & Ohio Canal, Conococheague Creek Aqueduct, Milepost 99.80, Williamsport, Washington County, MD

  6. Simulation of electrically controlled nematic liquid crystal Rochon prism

    NASA Astrophysics Data System (ADS)

    Buczkowska, M.; Derfel, G.

    2016-09-01

    Operation of an electrically controlled beam steering device based on Rochon prism made by use of nematic liquid crystal is modelled numerically. Deflection angles and angular distribution of light intensity in the deflected beam are calculated. Dynamics of the device is studied. Advantage of application of dual frequency nematic liquid crystal is demonstrated. Role of flexoelectric properties of the nematic is analyzed.

  7. Portable Remote Imaging Spectrometer (PRISM): Laboratory and Field Calibration

    NASA Technical Reports Server (NTRS)

    Mouroulis, Pantazis; Van Gorp, Byron; Green, Robert O.; Eastwood, Michael; Boardman, Joseph; Richardson, Brandon S.; Rodriguez, Jose I.; Urquiza, Eugenio; Franklin, Brian D.; Gao, Bo-Cai

    2012-01-01

    We report the characteristics of the Portable Remote Imaging Spectrometer, an airborne sensor specifically designed for the challenges of coastal ocean research. PRISM has high signal to noise ratio and uniformity, as well as low polarization sensitivity. Acquisition of high quality data has been demonstrated with the first engineering flight.

  8. 3. VIEW SOUTH SHOWING AQUEDUCT PRISM. NOTE 1920 TIMBER AND ...

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

    3. VIEW SOUTH SHOWING AQUEDUCT PRISM. NOTE 1920 TIMBER AND CONCRETE FLOORING SYSTEM, CUT STONE FACE OF PARAPET WALL, AND WROUGHT IRON BOLTS USED TO SECURE THE RUBBING RAIL. - Chesapeake & Ohio Canal, Conococheague Creek Aqueduct, Milepost 99.80, Williamsport, Washington County, MD

  9. Compact prisms for polarisation splitting of fibre laser beams

    SciTech Connect

    Davydov, B L; Yagodkin, D I

    2005-11-30

    Simple compact monoprisms for spatial splitting of polarised laser beams with relatively small diameters (no more than 1 mm) are considered. Prisms can be made of optically inactive CaCO{sub 3}, {alpha}-BaB{sub 2}O{sub 4} ({alpha}-BBO), LiIO{sub 3}, LiNbO{sub 3}, YVO{sub 4}, and TiO{sub 2} crystals known in polarisation optics. The exact solution of the Snell equation for the extraordinary wave reflected from a surface arbitrarily tilted to its wave vector is obtained. The analysis of variants of the solution allows the fabrication of prisms with any deviation angles of the extraordinary wave by preserving the propagation direction of the ordinary wave. Three variants of prisms are considered: with minimised dimensions, with the Brewster output of the extraordinary beam, and with the deviation of the extraordinary wave by 90{sup 0}. Calcite prisms with the deviation angles for the extraordinary beam {approx}19{sup 0} and 90{sup 0} are tested experimentally. (control of laser radiation parameters)

  10. 2. GENERAL VIEW ACROSS CANAL PRISM TO TOWPATH BERM SOUTH ...

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

    2. GENERAL VIEW ACROSS CANAL PRISM TO TOWPATH BERM SOUTH OF THE SPILLWAY; VIEW TO SOUTHWEST FROM ROUTE 146 EMBANKMENT. - Blackstone Canal Millbury Segment, Beginning northwest of State Route 146 & McCracken Road, running along west side of Route 146, Millbury, Worcester County, MA

  11. Synthesis and photocatalytic activity of porous bismuth oxychloride hexagonal prisms.

    PubMed

    Ding, Liyong; Chen, Huan; Wang, Qingqian; Zhou, Tengfei; Jiang, Qingqing; Yuan, Yuhong; Li, Jinlin; Hu, Juncheng

    2016-01-18

    Porous BiOCl hexagonal prisms have been successfully prepared through a simple solvothermal route. These novel BiOCl HPs with porous structures are assembled from nanoparticles and exhibit high activity and selectivity toward the photocatalytic aerobic oxidation of benzyl alcohol to benzaldehyde and degradation of methyl orange. PMID:26592759

  12. 3. GENERAL VIEW ACROSS CANAL PRISM TO TOWPATH BERM NORTH ...

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

    3. GENERAL VIEW ACROSS CANAL PRISM TO TOWPATH BERM NORTH OF THE SPILLWAY; VIEW TO WEST FROM ROUTE 146 EMBANKMENT. - Blackstone Canal Millbury Segment, Beginning northwest of State Route 146 & McCracken Road, running along west side of Route 146, Millbury, Worcester County, MA

  13. 1. GENERAL VIEW, TOWPATH BERM (CENTER) AND CANAL PRISM (LEFT) ...

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

    1. GENERAL VIEW, TOWPATH BERM (CENTER) AND CANAL PRISM (LEFT) SOUTH OF THE SPILLWAY; VIEW TO SOUTH. - Blackstone Canal Millbury Segment, Beginning northwest of State Route 146 & McCracken Road, running along west side of Route 146, Millbury, Worcester County, MA

  14. The Portable Remote Imaging Spectrometer (PRISM) Coastal Ocean Sensor

    NASA Technical Reports Server (NTRS)

    Mouroulis, Pantazis; VanGorp, Byron E.; Green, Robert O.; Eastwppd, Michael; Wilson, Daniel W.; Richardson, Brandon; Dierssen, Heidi

    2012-01-01

    PRISM is an airborne pushbroom imaging spectrometer intended to address the needs of airborne coastal ocean science research. Its critical characteristics are high throughput and signal-to-noise ratio, high uniformity of response to reduce spectral artifacts, and low polarization sensitivity. We give a brief overview of the instrument and results from laboratory calibration measurements regarding the spatial, spectral, radiometric and polarization characteristics.

  15. Liquid-crystal prisms for tip-tilt adaptive optics.

    PubMed

    Love, G D; Major, J V; Purvis, A

    1994-08-01

    Results from an electrically addressed liquid-crystal cell producing continuous phase profiles are presented. The adaptive deflection of a beam of light for use in a tip-tilt adaptive optics system is demonstrated. We compare the optical performance of liquid-crystal prisms with experimental data on atmospheric seeing at the William Herschel Telescope. PMID:19844566

  16. Electrowetting-Controlled Dual Liquid Prism for Adaptive Beam Steering

    NASA Astrophysics Data System (ADS)

    Cheng, Jiangtao

    2015-03-01

    The use of concentrating photovoltaic (CPV) technology has been the most promising method of harvesting solar radiation. These CPV systems often require motor-driven tracking devices to steer the sun's beams onto solar cells. The cost of maintaining these tracking systems is the primary inhibitor for widespread application. We aim to overcome the need for mechanical trackers through the use of an electrowetting-driven solar tracking (EWST) system. The electrowetting-driven solar tracking system consists of an array of novel electrowetting-controlled dual liquid prisms, which are filled with immiscible fluids that have large differences in refractive indices. The naturally formed meniscus between the fluids can function as a dynamic optical prism. Via the full-range modulation of the liquid prisms, incident sunlight can be adaptively tracked, steered, and focused onto CPV cells through a fixed optical condenser. Furthermore, unlike the conventional and cumbersome motor-driven tracking systems used today, the liquid prism system would be suitable for rooftop applications. The results of this project reveal that the EWST system has the potential to generate ~ 70% more green energy at 50% of the conventional capital cost.

  17. Cardiac rate detection method based on the beam splitter prism

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Liu, Xiaohua; Liu, Ming; Zhao, Yuejin; Dong, Liquan; Zhao, Ruirui; Jin, Xiaoli; Zhao, Jingsheng

    2013-09-01

    A new cardiac rate measurement method is proposed. Through the beam splitter prism, the common-path optical system of transmitting and receiving signals is achieved. By the focusing effect of the lens, the small amplitude motion artifact is inhibited and the signal-to-noise is improved. The cardiac rate is obtained based on the PhotoPlethysmoGraphy (PPG). We use LED as the light source and use photoelectric diode as the receiving tube. The LED and the photoelectric diode are on the different sides of the beam splitter prism and they form the optical system. The signal processing and display unit is composed by the signal processing circuit, data acquisition device and computer. The light emitted by the modulated LED is collimated by the lens and irradiates the measurement target through the beam splitter prism. The light reflected by the target is focused on the receiving tube through the beam splitter prism and another lens. The signal received by the photoelectric diode is processed by the analog circuit and obtained by the data acquisition device. Through the filtering and Fast Fourier Transform, the cardiac rate is achieved. We get the real time cardiac rate by the moving average method. We experiment with 30 volunteers, containing different genders and different ages. We compare the signals captured by this method to a conventional PPG signal captured concurrently from a finger. The results of the experiments are all relatively agreeable and the biggest deviation value is about 2bmp.

  18. Rotating prism design for continuous image compensation cameras.

    PubMed

    Waddell, J H

    1966-07-01

    The rotating prisms used in high-speed motion-picture cameras have been designed empirically since their first use thirty-two years ago. During that period, there have been advances made in glass technology and fabrication which have resulted in the production of better images. This paper summarizes the latest state of the art wherein it is demonstrated that prism design should not be confined to the D line of the spectrum, but expanded to cover the uv and ir portions of the spectrum. The prism design shall cover: (1) selection of the average angle of incidence for exposure; (2) the choice of glass or other transparent media; (3) the correlationship between image and film velocity; and (4) discussion of the inherent aberrations, namely, nonlinear distortion, sagittal and tangential coma, prismatic astigmatism, change in back focus due to prism rotation; (5) shuttering action; and (6) aperture design. There have only been fragmentary data published on the subject to date. It is necessary to secure this thirty years' experience before this datum is forever lost. Recommendation for future action is made, including computer studies for optimization of design. PMID:20049049

  19. Prism adaptation for spatial neglect after stroke: translational practice gaps

    PubMed Central

    Barrett, A. M.; Goedert, Kelly M.; Basso, Julia C.

    2012-01-01

    Spatial neglect increases hospital morbidity and costs in around 50% of the 795,000 people per year in the USA who survive stroke, and an urgent need exists to reduce the care burden of this condition. However, effective acute treatment for neglect has been elusive. In this article, we review 48 studies of a treatment of intense neuroscience interest: prism adaptation training. Due to its effects on spatial motor ‘aiming’, prism adaptation training may act to reduce neglect-related disability. However, research failed, first, to suggest methods to identify the 50–75% of patients who respond to treatment; second, to measure short-term and long-term outcomes in both mechanism-specific and functionally valid ways; third, to confirm treatment utility during the critical first 8 weeks poststroke; and last, to base treatment protocols on systematic dose–response data. Thus, considerable investment in prism adaptation research has not yet touched the fundamentals needed for clinical implementation. We suggest improved standards and better spatial motor models for further research, so as to clarify when, how and for whom prism adaptation should be applied. PMID:22926312

  20. Preapplication safety evaluation report for the Power Reactor Innovative Small Module (PRISM) liquid-metal reactor. Final report

    SciTech Connect

    Donoghue, J.E.; Donohew, J.N.; Golub, G.R.; Kenneally, R.M.; Moore, P.B.; Sands, S.P.; Throm, E.D.; Wetzel, B.A.

    1994-02-01

    This preapplication safety evaluation report (PSER) presents the results of the preapplication desip review for die Power Reactor Innovative Small Module (PRISM) liquid-mew (sodium)-cooled reactor, Nuclear Regulatory Commission (NRC) Project No. 674. The PRISM conceptual desip was submitted by the US Department of Energy in accordance with the NRC`s ``Statement of Policy for the Regulation of Advanced Nuclear Power Plants`` (51 Federal Register 24643). This policy provides for the early Commission review and interaction with designers and licensees. The PRISM reactor desip is a small, modular, pool-type, liquid-mew (sodium)-cooled reactor. The standard plant design consists of dim identical power blocks with a total electrical output rating of 1395 MWe- Each power block comprises three reactor modules, each with a thermal rating of 471 MWt. Each module is located in its own below-grade silo and is co to its own intermediate heat transport system and steam generator system. The reactors utilize a metallic-type fuel, a ternary alloy of U-Pu-Zr. The design includes passive reactor shutdown and passive decay heat removal features. The PSER is the NRC`s preliminary evaluation of the safety features in the PRISM design, including the projected research and development programs required to support the design and the proposed testing needs. Because the NRC review was based on a conceptual design, the PSER did not result in an approval of the design. Instead it identified certain key safety issues, provided some guidance on applicable licensing criteria, assessed the adequacy of the preapplicant`s research and development programs, and concluded that no obvious impediments to licensing the PRISM design had been identified.

  1. Superconducting magnetic Wollaston prism for neutron spin encoding

    SciTech Connect

    Li, F. Parnell, S. R.; Wang, T.; Baxter, D. V.; Hamilton, W. A.; Maranville, B. B.; Semerad, R.; Cremer, J. T.; Pynn, R.

    2014-05-15

    A magnetic Wollaston prism can spatially split a polarized neutron beam into two beams with different neutron spin states, in a manner analogous to an optical Wollaston prism. Such a Wollaston prism can be used to encode the trajectory of neutrons into the Larmor phase associated with their spin degree of freedom. This encoding can be used for neutron phase-contrast radiography and in spin echo scattering angle measurement (SESAME). In this paper, we show that magnetic Wollaston prisms with highly uniform magnetic fields and low Larmor phase aberration can be constructed to preserve neutron polarization using high temperature superconducting (HTS) materials. The Meissner effect of HTS films is used to confine magnetic fields produced electromagnetically by current-carrying HTS tape wound on suitably shaped soft iron pole pieces. The device is cooled to ∼30 K by a closed cycle refrigerator, eliminating the need to replenish liquid cryogens and greatly simplifying operation and maintenance. A HTS film ensures that the magnetic field transition within the prism is sharp, well-defined, and planar due to the Meissner effect. The spin transport efficiency across the device was measured to be ∼98.5% independent of neutron wavelength and energizing current. The position-dependent Larmor phase of neutron spins was measured at the NIST Center for Neutron Research facility and found to agree well with detailed simulations. The phase varies linearly with horizontal position, as required, and the neutron beam shows little depolarization. Consequently, the device has advantages over existing devices with similar functionality and provides the capability for a large neutron beam (20 mm × 30 mm) and an increase in length scales accessible to SESAME to beyond 10 μm. With further improvements of the external coupling guide field in the prototype device, a larger neutron beam could be employed.

  2. Prism adaptation contrasts perceptual habituation for repetitive somatosensory stimuli.

    PubMed

    Torta, D M; Tatu, M K; Cotroneo, D; Alamia, A; Folegatti, A; Trojan, J

    2016-03-01

    Prism adaptation (PA) is a non-invasive procedure that requires performing a visuo-motor pointing task while wearing prism goggles inducing a visual displacement of the pointed target. This procedure involves a reorganization of sensorimotor coordination, and induces long-lasting effects on numerous higher-order cognitive functions in healthy volunteers and neglect patients. Prismatic displacement (PD) of the visual field can be induced when prisms are worn but no sensorimotor task is required. In this case, it is unlikely that any subsequent reorganization takes place. The effects of PD are short-lived in the sense that they last as long as prisms are worn. In this study we aimed, to the best of our knowledge for the first time, at investigating whether PA and PD induce changes in the perception of intensity of nociceptive and non- nociceptive somatosensory stimuli. We induced, in healthy volunteers, PD (experiment 1), or PA (experiment 2) and asked participants to rate the intensity of the stimuli applied to the hand undergoing the visuo-proprioceptive conflict (experiment 1) or adaptation (experiment 2). Our results indicate that: 1) the visuo-proprioceptive conflict induced by PD does not reduce the perceived intensity of the stimuli, 2) PA prevents perceptual habituation for both nociceptive and non-nociceptive somatosensory stimuli. Moreover, to investigate the possible underlying mechanisms of the effects of PA we conducted a third experiment in which stimuli were applied both at the adapted and the non-adapted hand. In line with the results of experiment 2, we found that perceptual habituation was prevented for stimuli applied onto the adapted hand. Moreover, we observed the same finding for stimuli applied onto the non-adapted hand. This result suggests that the detention of habituation is not merely driven by changes in spatial attention allocation. Taken together, these data indicate that prisms can affect the perceived intensity of somatosensory stimuli

  3. Superconducting magnetic Wollaston prism for neutron spin encoding.

    PubMed

    Li, F; Parnell, S R; Hamilton, W A; Maranville, B B; Wang, T; Semerad, R; Baxter, D V; Cremer, J T; Pynn, R

    2014-05-01

    A magnetic Wollaston prism can spatially split a polarized neutron beam into two beams with different neutron spin states, in a manner analogous to an optical Wollaston prism. Such a Wollaston prism can be used to encode the trajectory of neutrons into the Larmor phase associated with their spin degree of freedom. This encoding can be used for neutron phase-contrast radiography and in spin echo scattering angle measurement (SESAME). In this paper, we show that magnetic Wollaston prisms with highly uniform magnetic fields and low Larmor phase aberration can be constructed to preserve neutron polarization using high temperature superconducting (HTS) materials. The Meissner effect of HTS films is used to confine magnetic fields produced electromagnetically by current-carrying HTS tape wound on suitably shaped soft iron pole pieces. The device is cooled to ~30 K by a closed cycle refrigerator, eliminating the need to replenish liquid cryogens and greatly simplifying operation and maintenance. A HTS film ensures that the magnetic field transition within the prism is sharp, well-defined, and planar due to the Meissner effect. The spin transport efficiency across the device was measured to be ~98.5% independent of neutron wavelength and energizing current. The position-dependent Larmor phase of neutron spins was measured at the NIST Center for Neutron Research facility and found to agree well with detailed simulations. The phase varies linearly with horizontal position, as required, and the neutron beam shows little depolarization. Consequently, the device has advantages over existing devices with similar functionality and provides the capability for a large neutron beam (20 mm × 30 mm) and an increase in length scales accessible to SESAME to beyond 10 μm. With further improvements of the external coupling guide field in the prototype device, a larger neutron beam could be employed. PMID:24880360

  4. Early Jurassic Volcanic Rocks from the Raohe Accretionary Complex of NE China: Petrogenesis and Tectonic Implications

    NASA Astrophysics Data System (ADS)

    Wang, Zhihui; Ge, Wenchun

    2016-04-01

    The Raohe accretionary complex is located at the boundary between the Russian Far East and Northeast China, and is an important part of the Western Pacific Ocean tectonic regime. However, owing to the lack of precise age and geochemical constraints, the tectonic setting and petrogenesis of magmatic rocks in this area have been controversial, which has led to the debate on crustal growth mechanisms and subduction accretionary processes in the Northeast China. Herein, we report newly-defined calc-alkaline andesites, dacites, rhyolites, Nb-enriched basaltic-andesites and andesites, and N-MORB type basalts and basaltic-andesites from the Raohe accretionary complex, NE China. All these volcanic rocks are collected from rocks mapped previously as the Late Triassic to Early Jurassic stratums. LA-ICP-MS zircon U-Pb dating for one andesite, one dacites and three rhyolites indicate the occurrence of magmatic events in the Early Jurassic (186-174 Ma). They have positive ɛHf(t) values of +3.4 to +10.6 and relatively high (87Sr/86Sr)i values of 0.704711 to 0.710235. The calc-alkaline andesites, dacites and rhyolites are typical arc magmas, with moderately enriched LILEs and LREEs, distinctly negative HFSEs, consistent with the chemistry of volcanic rocks from an active continental margin setting. The Nb-enriched basaltic-andesites and andesites have higher TiO2, Nb, and Zr contents, higher Nb/Ta (24.03-87.60), Nb/U (11.89-75.94), (Nb/Th)PM (0.67-2.70), and (Nb/La)PM (1.95-5.00) ratios than typical arc basalts. They are relatively enriched in Nb, Zr, Hf and Ti. They have negative ɛNd(t) values of -5.47 to -6.04 and relatively variable (87Sr/86Sr)i values of 0.704648 to 0.711430, suggesting that they were possibly generated by a partial melting of mantle wedge peridotites metasomatized by slab-derived adakitic melts and minor fluids. The N-MORB type basalts and basaltic-andesites have comparatively low TiO2 concentrations (1.18-1.42 wt.%), show almost flat REE patterns with

  5. Reconciling the detrital zircon record and crustal growth within juvenile accretionary orogens

    NASA Astrophysics Data System (ADS)

    Spencer, C. J.; Cawood, P. A.; Roberts, N. M. W.

    2014-12-01

    Ancient cratons are generally characterised by Archaean cores surrounded by Proterozoic accretionary belts with large volumes of juvenile crust. Their crustal growth histories provide important insights into the genesis of continents and orogenic evolution. Whole-rock and detrital zircon isotopic studies are often used to deduce those histories, but the extent to which representative lithologies within the orogens are reliably sampled for such studies is not well established. This is especially true in cases where juvenile, zircon-poor mafic crust comprises a significant proportion of an orogen such as the East African (0.8-0.5 Ga), Namaqua-Natal (1.2-1.0 Ga), Trans-Hudson (1.9-1.8 Ga), and Kola (2.5 Ga). In particular, the Mesoproterozoic Namaqua-Natal orogenic belt (NNO) fringing the Kalahari Craton is a case in point in which Nd isotopic studies of whole-rock outcrop samples and U-Pb-Hf isotopic studies of detrital zircons from sediments of the Orange River (which drains the NNO) show different crust-formation ages and proportions of new and reworked crustal material. We hypothesise that this discrepancy is due to biasing of the detrital zircon record towards felsic rocks. Understanding the representative nature of the crustal archive preserved in detrital zircons remains critical for many studies of crustal evolution. We present data that: (a) addresses the scale of potential bias within an accretionary orogen containing large proportions of juvenile material, (b) demonstrates how the whole-rock and detrital zircon records can be reconciled for the Namaqua-Natal orogen to start, and (c) can be used to evaluate the effect of zircon bias on previous crustal growth models.

  6. Experimental static aerodynamics of a regular hexagonal prism in a low density hypervelocity flow

    NASA Technical Reports Server (NTRS)

    Guy, R. W.; Mueller, J. N.; Lee, L. P.

    1972-01-01

    A regular hexagonal prism, having a fineness ratio of 1.67, has been tested in a wind tunnel to determine its static aerodynamic characteristics in a low-density hypervelocity flow. The prism tested was a 1/4-scale model of the graphite heat shield which houses the radioactive fuel for the Viking spacecraft auxiliary power supply. The basic hexagonal prism was also modified to simulate a prism on which ablation of one of the six side flats had occurred. This modified hexagonal prism was tested to determine the effects on the aerodynamic characteristics of a shape change caused by ablation during a possible side-on stable reentry.

  7. Ophiolites in the Xing'an-Inner Mongolia accretionary belt of the CAOB: Implications for two cycles of seafloor spreading and accretionary orogenic events

    NASA Astrophysics Data System (ADS)

    Song, Shuguang; Wang, Ming-Ming; Xu, Xin; Wang, Chao; Niu, Yaoling; Allen, Mark B.; Su, Li

    2015-10-01

    The Xing'an-Inner Mongolia accretionary belt in the southeastern segment of the Central Asian Orogenic Belt (CAOB) was produced by the long-lived subduction and eventual closure of the Paleo-Asian Ocean and by the convergence between the North China Craton and the Mongolian microcontinent. Two ophiolite belts have been recognized: the northern Erenhot-Hegenshan-Xi-Ujimqin ophiolite belt and the southern Solonker-Linxi ophiolite belt. Most basalts in the northern ophiolite belt exhibit characteristics of normal-type to enriched-type mid-ocean ridge basalt affinities with depleted Nd isotopic composition (ɛNd(t) > +5), comparable to modern Eastern Pacific mid-ocean ridge basalts. Most basaltic rocks in the southern belt show clear geochemical features of suprasubduction zone-type oceanic crust, probably formed in an arc/back-arc environment. The inferred back-arc extension along the Solonker-Linxi belt started at circa 280 Ma. Statistics of all the available age data for the ophiolites indicates two cycles of seafloor spreading/subduction, which gave rise to two main epochs of magmatic activity at 500-410 Ma and 360-220 Ma, respectively, with a gap of ~50 million years (Myr). The spatial and temporal distribution of the ophiolites and concurrent igneous rocks favor bilateral subduction toward the two continental margins in the convergence history, with final collision at ~230-220 Ma. In the whole belt, signals of continental collision and Himalayan-style mountain building are lacking. We thus conclude that the Xing'an-Inner Mongolia segment of the CAOB experienced two cycles of seafloor subduction, back-arc extension, and final "Appalachian-type" soft collision.

  8. Nano-accuracy measurements and the surface profiler by use of Monolithic Hollow Penta-Prism for precision mirror testing

    NASA Astrophysics Data System (ADS)

    Qian, Shinan; Wayne, Lewis; Idir, Mourad

    2014-09-01

    We developed a Monolithic Hollow Penta-Prism Long Trace Profiler-NOM (MHPP-LTP-NOM) to attain nano-accuracy in testing plane- and near-plane-mirrors. A new developed Monolithic Hollow Penta-Prism (MHPP) combined with the advantages of PPLTP and autocollimator ELCOMAT of the Nano-Optic-Measuring Machine (NOM) is used to enhance the accuracy and stability of our measurements. Our precise system-alignment method by using a newly developed CCD position-monitor system (PMS) assured significant thermal stability and, along with our optimized noise-reduction analytic method, ensured nano-accuracy measurements. Herein we report our tests results; all errors are about 60 nrad rms or less in tests of plane- and near-plane- mirrors.

  9. PRISM (processes research by an imaging spaceborne mission) high-resolution hyperspectral imager for scientific land processes monitoring applications

    NASA Astrophysics Data System (ADS)

    Kunkel, Bernd P.; Blechinger, Fritz; Lutz, Reinhold; Posselt, Winfried; Del Bello, Umberto; Meynart, Roland; Lobb, Daniel R.; Saint-Pe, Olivier

    1995-11-01

    Dasa (Daimler-Benz Aerospace) currently is in charge of an ESA contract for the PRISM feasibility study, including MATRA MS/France and SIRA/UK. The main PRISM mission objectives are to monitor selected target areas with emphasis on bio-chemical stress analyses which are the subject of changes such as vegetation, in particular deforestation; further areas include glaciers, land/water boundaries, and similar features. The Dasa study team makes use of a similar ESA instrument currently the subject of dedicated subunits technology developments, the HRIS (high resolution imaging spectrometer), also lead by Dasa. Its main features and technology developments are covered in a survey. PRISM is covering most of the HRIS features, i.e., it will have an imaging spectrometer segment for the visible/NIR and the SWIR spectrum (450-2350 nm) as HRIS, but implements four MIR and TIR channels to provide surface temperature data, represented by linear detector arrays (essentially the features of another currently pursued ESA development program designated HRTIR). In a first study phase it also included a novel feature, a wide-angle two-axis pointing system for along- and across-track pointing in order to yield multi-directional reflectance data of dedicated targets, which turned out to be the greatest design driver in the instrument, it was omitted in the later phases. The geometric sampling interval is defined to 50 m (design goal) at 50 km swath. PRISM is currently studied in a feasibility study in a competitive way by two teams, one being lead by Dasa. At the time of the Symposium both studies are completed. The results of the Dasa team are presented. Since PRISM covers most of the HRIS mission it is rather likely that in the case of a successful concept feasibility proof (performance and technology wise), it may later replace the HRIS instrument. It is anticipated that a major part of the technology developments currently performed for HRIS will be utilized -- with some

  10. Characteristic analysis of a polarization output coupling Porro prism resonator

    NASA Astrophysics Data System (ADS)

    Yang, Hailong; Meng, Junqing; Chen, Weibiao

    2015-02-01

    An Electro-optical Q-switched Nd:YAG slab laser with a crossed misalignment Porro prism resonator for space applications has been theoretically and experimentally investigated. The phase shift induced by the combination of different wave plates and Porro prism azimuth angles have been studied for creating high loss condition prior to Q-switching. The relationship of the effective output coupling reflectivity and the employed Q-switch driving voltage is explored by using Jones matrix optics. In the experiment, the maximum output pulse energy of 93 mJ with 14-ns pulse duration is obtained at the repetition rate of 20 Hz and the optical-to-optical conversion efficiency is 16.8%. The beam quality factors are M 2 x = 2.5 and M 2y = 2.2, respectively.

  11. Relationship between frequency and deflection angle in the DNA prism.

    PubMed

    Chen, Zhen; Dorfman, Kevin D

    2013-01-01

    The DNA prism is a modification of the standard pulsed-field electrophoresis protocol to provide a continuous separation, where the DNA are deflected at an angle that depends on their molecular weight. The standard switchback model for the DNA prism predicts a monotonic increase in the deflection angle as a function of the frequency for switching the field until a plateau regime is reached. However, experiments indicate that the deflection angle achieves a maximum value before decaying to a size-independent value at high frequencies. Using Brownian dynamics simulations, we show that the maximum in the deflection angle is related to the reorientation time for the DNA and the decay in deflection angle at high frequencies is due to inadequate stretching. The generic features of the dependence of the deflection angle on molecular weight, switching frequency, and electric field strength explain a number of experimental phenomena. PMID:23410375

  12. Design of partially optically stable reflector systems and prisms

    NASA Astrophysics Data System (ADS)

    Tsai, Chuang-Yu

    2010-09-01

    The characteristics and design method of the total optically stable (TOS) reflector systems/prisms were introduced in an early paper (Tsai and Lin in Appl. Opt. 47:4158-4163, 2008), where only two types of TOS reflector system exist, namely preservation or retroreflection. In this paper, we introduce the partially optically stable (POS) reflector system, which is only optically stable about a specific directional vector; nevertheless, the exiting light ray is not restricted to preservation or retroreflection. The proposed paper also presents an analytic method for the design of POS reflector systems comprised of multiple reflectors. Furthermore, it is shown that a POS prism can be obtained by adding two refracting flat boundary surfaces with specific conditions at the entrance and exit positions of the light ray in an optical system with multiple reflectors.

  13. Planar prism spectrometer based on adiabatically connected waveguiding slabs

    NASA Astrophysics Data System (ADS)

    Civitci, F.; Hammer, M.; Hoekstra, H. J. W. M.

    2016-04-01

    The device principle of a prism-based on-chip spectrometer for TE polarization is introduced. The spectrometer exploits the modal dispersion in planar waveguides in a layout with slab regions having two different thicknesses of the guiding layer. The set-up uses parabolic mirrors, for the collimation of light of the input waveguide and focusing of the light to the receiver waveguides, which relies on total internal reflection at the interface between two such regions. These regions are connected adiabatically to prevent unwanted mode conversion and loss at the edges of the prism. The structure can be fabricated with two wet etching steps. The paper presents basic theory and a general approach for device optimization. The latter is illustrated with a numerical example assuming SiON technology.

  14. Extremely simple single-prism ultrashort- pulse compressor.

    PubMed

    Akturk, Selcuk; Gu, Xun; Kimmel, Mark; Trebino, Rick

    2006-10-16

    We have designed and demonstrated a very simple and compact ultrashort-pulse compressor using a single prism and a corner-cube. Our design is significantly easier to align and tune compared with previous designs. Angle-tuning the prism wavelength-tunes, and translating the corner cube varies the group-delay dispersion over a wide range. When tuned, the device automatically maintains zero angular dispersion, zero pulse-front tilt, zero spatial chirp, and unity magnification. The device can easily be built so that its output beam remains collinear with the input beam, and when the input beam or pulse compressor moves, the input and output beams remain collinear. PMID:19529405

  15. Viewing Hypermedia through the Prism of Evaluation.

    ERIC Educational Resources Information Center

    Gleim, Candice W.; Harvey, Francis A.

    This paper seeks to establish evaluation as an important concern in hypermedia research and development, and presents a review of current hypermedia evaluation research with a prescriptive focus. Characteristics of hypermedia currently attracting the attention of instructional developers are discussed and conclusions drawn from recent evaluation…

  16. Web-based Tools for Educators: Outreach Activities of the Polar Radar for Ice Sheet Measurements (PRISM) Project

    NASA Astrophysics Data System (ADS)

    Braaten, D. A.; Holvoet, J. F.; Gogineni, S.

    2003-12-01

    The Radar Systems and Remote Sensing Laboratory at the University of Kansas (KU) has implemented extensive outreach activities focusing on Polar Regions as part of the Polar Radar for Ice Sheet Measurements (PRISM) project. The PRISM project is developing advanced intelligent remote sensing technology that involves radar systems, an autonomous rover, and communications systems to measure detailed ice sheet characteristics, and to determine bed conditions (frozen or wet) below active ice sheets in both Greenland and Antarctica. These measurements will provide a better understanding of the response of polar ice sheets to global climate change and the resulting impact the ice sheets will have on sea level rise. Many of the research and technological development aspects of the PRISM project, such as robotics, radar systems, climate change and exploration of harsh environments, can kindle an excitement and interest in students about science and technology. These topics form the core of our K-12 education and training outreach initiatives, which are designed to capture the imagination of young students, and prompt them to consider an educational path that will lead them to scientific or engineering careers. The K-12 PRISM outreach initiatives are being developed and implemented in a collaboration with the Advanced Learning Technology Program (ALTec) of the High Plains Regional Technology in Education Consortium (HPR*TEC). ALTec is associated with the KU School of Education, and is a well-established educational research center that develops and hosts web tools to enable teachers nationwide to network, collaborate, and share resources with other teachers. An example of an innovative and successful web interface developed by ALTec is called TrackStar. Teachers can use TrackStar over the Web to develop interactive, resource-based lessons (called tracks) on-line for their students. Once developed, tracks are added to the TrackStar database and can be accessed and modified

  17. Prism-coupled light emission from tunnel junctions

    NASA Technical Reports Server (NTRS)

    Ushioda, S.; Rutledge, J. E.; Pierce, R. M.

    1985-01-01

    Completely p-polarized light emission has been observed from smooth Al-AlO(x)-Au tunnel junctions placed on a prism coupler. The angle and polarization dependence demonstrate unambiguously that the emitted light is radiated by the fast-mode surface plasmon polariton. The emission spectra suggest that the dominant process for the excitation of the fast mode is through conversion of the slow mode to the fast mode mediated by residual roughness on the junction surface.

  18. Stereovision Imaging in Smart Mobile Phone Using Add on Prisms

    NASA Astrophysics Data System (ADS)

    Bar-Magen Numhauser, Jonathan; Zalevsky, Zeev

    2014-03-01

    In this work we present the use of a prism-based add on component installed on top of a smart phone to achieve stereovision capabilities using iPhone mobile operating system. Through these components and the combination of the appropriate application programming interface and mathematical algorithms the obtained results will permit the analysis of possible enhancements for new uses to such system, in a variety of areas including medicine and communications.

  19. Measurement of chalcogenide glass optical dispersion using a mid-infrared prism coupler

    SciTech Connect

    Qiao, Hong; Anheier, Norman C.; Musgraves, Jonathan D.; Richardson, Kathleen; Hewak, Daniel W.

    2011-05-01

    Physical properties of chalcogenide glass, including broadband infrared transparency, high refractive index, low glass transition temperature, and nonlinear properties, make them attractive candidates for advanced mid-infrared (3 to 12 {micro}m) optical designs. Efforts focused at developing new chalcogenide glass formulations and processing methods require rapid quantitative evaluation of their optical contents to guide the materials research. However, characterization of important optical parameters such as optical dispersion remains a slow and costly process, generally with limited accuracy. The recent development of a prism coupler at the Pacific Northwest National Laboratory (PNNL) now enables rapid, high precision measurement of refractive indices at discrete wavelengths from the visible to the mid-infrared. Optical dispersion data of several chalcogenide glass families were collected using this method. Variations in the optical dispersion were correlated to glass composition and compared against measurements using other methods. While this work has been focused on facilitating chalcogenide glass synthesis, mid-infrared prism coupler analysis has broader applications to other mid-infrared optical material development efforts, including oxide glasses and crystalline materials.

  20. Behaviour of concrete beams reinforced withFRP prestressed concrete prisms

    NASA Astrophysics Data System (ADS)

    Svecova, Dagmar

    same ultimate capacity, but reinforced with either steel, PCP or FRP rebars, the service load deflections of beams reinforced with PCP are comparable to that of a steel reinforced concrete beam, and are four times smaller than the deflection of the companion FRP reinforced beam. Similarly, the crack width of the PCP reinforced beams under service loads is comparable to that of the steel reinforced beam while the FRP reinforced beam developed unacceptably wide cracks. In the analytical part comprehensive analysis of the experimental data in both flexure and shear is performed. It is determined that the existing design expressions for ultimate flexural strength and service load deflection calculation cannot accurately predict the response of PCP reinforced beams. Accordingly, new expressions for calculation of deflection, crack width, tension stiffening, and ultimate capacity of the PCP reinforced beams are proposed. The predictions of the proposed methods of analysis agree very well with the corresponding experimental data. Based on the results of the current study, it is concluded that high strength concrete prisms prestressed with carbon fibre reinforced plastic bars can be used as reinforcement in concrete structures to avoid the problems of large deflections and wide cracks under service loads.

  1. Controllable Sonar Lenses and Prisms Based on ERFs

    NASA Technical Reports Server (NTRS)

    Bar-Cohen, Yoseph; Sherrit, Stewart; Chang, Zensheu; Bao, Xiaoqi; Paustian, Iris; Lopes, Joseph; Folds, Donald

    2004-01-01

    Sonar-beam-steering devices of the proposed type would contain no moving parts and would be considerably smaller and less power-hungry, relative to conventional multiple-beam sonar arrays. The proposed devices are under consideration for installation on future small autonomous underwater vehicles because the sizes and power demands of conventional multiple-beam arrays are excessive, and motors used in single-beam mechanically scanned systems are also not reliable. The proposed devices would include a variety of electrically controllable acoustic prisms, lenses, and prism/lens combinations both simple and compound. These devices would contain electrorheological fluids (ERFs) between electrodes. An ERF typically consists of dielectric particles floating in a dielectric fluid. When an electric field is applied to the fluid, the particles become grouped into fibrils aligned in rows, with a consequent increase in the viscosity of the fluid and a corresponding increase in the speed of sound in the fluid. The change in the speed of sound increases with an increase in the applied electric field. By thus varying the speed of sound, one varies the acoustic index of refraction, analogously to varying the index of refraction of an optical lens or prism. In the proposed acoustic devices, this effect would be exploited to control the angles of refraction of acoustic beams, thereby steering the beams and, in the case of lenses, controlling focal lengths.

  2. Spatial Compression Impairs Prism Adaptation in Healthy Individuals

    PubMed Central

    Scriven, Rachel J.; Newport, Roger

    2013-01-01

    Neglect patients typically present with gross inattention to one side of space following damage to the contralateral hemisphere. While prism-adaptation (PA) is effective in ameliorating some neglect behaviors, the mechanisms involved and their relationship to neglect remain unclear. Recent studies have shown that conscious strategic control (SC) processes in PA may be impaired in neglect patients, who are also reported to show extraordinarily long aftereffects compared to healthy participants. Determining the underlying cause of these effects may be the key to understanding therapeutic benefits. Alternative accounts suggest that reduced SC might result from a failure to detect prism-induced reaching errors properly either because (a) the size of the error is underestimated in compressed visual space or (b) pathologically increased error-detection thresholds reduce the requirement for error correction. The purpose of this study was to model these two alternatives in healthy participants and to examine whether SC and subsequent aftereffects were abnormal compared to standard PA. Each participant completed three PA procedures within a MIRAGE mediated reality environment with direction errors recorded before, during and after adaptation. During PA, visual feedback of the reach could be compressed, perturbed by noise, or represented veridically. Compressed visual space significantly reduced SC and aftereffects compared to control and noise conditions. These results support recent observations in neglect patients, suggesting that a distortion of spatial representation may successfully model neglect and explain neglect performance while adapting to prisms. PMID:23675332

  3. SSC analysis of the GEMs for reactivity control in PRISM

    SciTech Connect

    Slovik, G.C.; Rodnizki, J.

    1992-01-01

    The performance of three Gas Expansion Modules (GEMS) utilized the Advanced Liquid Metal Reactor (ALMR) concept, PRISM, was analyzed using the computer code, SSC. GE has submitted the PRISM design for a Preapplication Safety Evaluation Report (PSER). The draft PSER indicated a potential weakness in the Unscrammed Loss of Flow (ULOF) event, and GE modified the design by adding three GEMs. The PRISM design was analyzed by SSC for two cases. First, the design's original response to a ULOF where one Electro Magnetic (EM) pump fails to produce a coastdown was analyzed. Then the revised design with the GEMs included was analyzed. The original design had little or no safety margin for this case. The peak fuel temperature in the hot channel was predicted to be 1358K, which is above the solidus temperature of the fuel. However, after the GEMs were added, the loss of one EM pump coastdown became a benign event. The GEM feedback was predicted by SSC to dominate the other reactivity feedbacks and the GEMS, essentially, responded like passive control rods. The fuel temperature quickly dropped below operating temperatures, while the margin to sodium boiling was predicted to be greater than 350K.

  4. SSC analysis of the GEMs for reactivity control in PRISM

    SciTech Connect

    Slovik, G.C.; Rodnizki, J.

    1992-12-31

    The performance of three Gas Expansion Modules (GEMS) utilized the Advanced Liquid Metal Reactor (ALMR) concept, PRISM, was analyzed using the computer code, SSC. GE has submitted the PRISM design for a Preapplication Safety Evaluation Report (PSER). The draft PSER indicated a potential weakness in the Unscrammed Loss of Flow (ULOF) event, and GE modified the design by adding three GEMs. The PRISM design was analyzed by SSC for two cases. First, the design`s original response to a ULOF where one Electro Magnetic (EM) pump fails to produce a coastdown was analyzed. Then the revised design with the GEMs included was analyzed. The original design had little or no safety margin for this case. The peak fuel temperature in the hot channel was predicted to be 1358K, which is above the solidus temperature of the fuel. However, after the GEMs were added, the loss of one EM pump coastdown became a benign event. The GEM feedback was predicted by SSC to dominate the other reactivity feedbacks and the GEMS, essentially, responded like passive control rods. The fuel temperature quickly dropped below operating temperatures, while the margin to sodium boiling was predicted to be greater than 350K.

  5. Spatial compression impairs prism adaptation in healthy individuals.

    PubMed

    Scriven, Rachel J; Newport, Roger

    2013-01-01

    Neglect patients typically present with gross inattention to one side of space following damage to the contralateral hemisphere. While prism-adaptation (PA) is effective in ameliorating some neglect behaviors, the mechanisms involved and their relationship to neglect remain unclear. Recent studies have shown that conscious strategic control (SC) processes in PA may be impaired in neglect patients, who are also reported to show extraordinarily long aftereffects compared to healthy participants. Determining the underlying cause of these effects may be the key to understanding therapeutic benefits. Alternative accounts suggest that reduced SC might result from a failure to detect prism-induced reaching errors properly either because (a) the size of the error is underestimated in compressed visual space or (b) pathologically increased error-detection thresholds reduce the requirement for error correction. The purpose of this study was to model these two alternatives in healthy participants and to examine whether SC and subsequent aftereffects were abnormal compared to standard PA. Each participant completed three PA procedures within a MIRAGE mediated reality environment with direction errors recorded before, during and after adaptation. During PA, visual feedback of the reach could be compressed, perturbed by noise, or represented veridically. Compressed visual space significantly reduced SC and aftereffects compared to control and noise conditions. These results support recent observations in neglect patients, suggesting that a distortion of spatial representation may successfully model neglect and explain neglect performance while adapting to prisms. PMID:23675332

  6. Effect of prism adaptation on thermoregulatory control in humans.

    PubMed

    Calzolari, Elena; Gallace, Alberto; Moseley, G Lorimer; Vallar, Giuseppe

    2016-01-01

    The physiological regulation of skin temperature can be modulated not only by autonomic brain regions, but also by a network of higher-level cortical areas involved in the maintenance of a coherent representation of the body. In this study we assessed in healthy participants if the sensorimotor changes taking place during motor adaptation to the lateral displacement of the visual scene induced by wearing prismatic lenses (prism adaptation, PA), and the aftereffects, after prisms' removal, on the ability to process spatial coordinates, were associated with skin temperature regulation changes. We found a difference in thermoregulatory control as a function of the direction of the prism-induced displacement of the visual scene, and the subsequent sensorimotor adaptation. After PA to rightward displacing lenses, with leftward aftereffects (the same directional procedure efficaciously used for ameliorating left spatial neglect in right-brain-damaged patients) the hands' temperature decreased. Conversely, after adaptation to neutral lenses, and PA to leftward displacing lenses, with rightward aftereffects, the temperature of both hands increased. These results suggest a lateral asymmetry in the effects of PA on skin temperature regulation, and a relationship between body spatial representations and homeostatic control in humans. PMID:26354443

  7. Tectonic imbrication of Palaeo- and Neo-Tethyan accretionary complexes in the central Pontides, Turkey

    NASA Astrophysics Data System (ADS)

    Okay, A. I.; Tuysuz, O.; Satir, M.; Eren, R. H.

    2003-04-01

    -eclogite thrust slice was previously also regarded as part of the Palaeo-Tethyan (Triassic) subduction-accretion complex. However, recent isotopic dating of the Elekdag eclogites have yielded Cretaceous ages, indicating that Palaeo- and Neo-Tethyan accretionary complexes were thrust imbricated during the Late Cretaceous subduction. A similar observation was recently reported from the Eskisehir region, 370 km to the west, where Triassic blueschists and eclogites are imbricated with the Upper Cretaceous accretionary complexes. Close association of Paleo- and Neo-Tethyan accretionary complexes along the Izmir-Ankara suture indicates that the latest Triassic-earliest Jurassic Cimmeride orogeny in Turkey was of accretional rather than collisional nature, and that the Izmir-Ankara suture represents a long-lived plate boundary of late Palaeozoic to early Tertiary age.

  8. Analytical direct solutions of the Risley prism systems for tracking and pointing.

    PubMed

    Peng, Qi; Wang, Xinghui; Ren, Ge; Chen, Hongbin; Cao, Lei; Wang, Jihong

    2014-05-01

    The Risley prism systems, which had many different configurations, are only composed of two wedge prisms. The expressions of the direction cosines of the refractive ray of the two wedge prisms are given by nonparaxial ray tracing in a local coordinate referenced to the wedge prism, and the power of ray deviation of the two wedge prisms are shown by curves for systems using prisms of different materials and opening angles. The analytical direct solutions of the Risley prism systems are derived from the expressions of the direction cosines of the wedge prism through the coordinate transformation, and are also deduced from the two exact orientations for the same pointing position of precision tracking and pointing systems, which arise from applications of the Risley prisms to free-space communications. The exact expressions for the problem of precision tracking are generalized to investigate the synthesis of tracking a given target, i.e., to track a desirable path on some plane perpendicular to the optical axis of the system by controlling the circular motion of the two prisms. PMID:24921893

  9. First-order approximation error analysis of Risley-prism-based beam directing system.

    PubMed

    Zhao, Yanyan; Yuan, Yan

    2014-12-01

    To improve the performance of a Risley-prism system for optical detection and measuring applications, it is necessary to be able to determine the direction of the outgoing beam with high accuracy. In previous works, error sources and their impact on the performance of the Risley-prism system have been analyzed, but their numerical approximation accuracy was not high. Besides, pointing error analysis of the Risley-prism system has provided results for the case when the component errors, prism orientation errors, and assembly errors are certain. In this work, the prototype of a Risley-prism system was designed. The first-order approximations of the error analysis were derived and compared with the exact results. The directing errors of a Risley-prism system associated with wedge-angle errors, prism mounting errors, and bearing assembly errors were analyzed based on the exact formula and the first-order approximation. The comparisons indicated that our first-order approximation is accurate. In addition, the combined errors produced by the wedge-angle errors and mounting errors of the two prisms together were derived and in both cases were proved to be the sum of errors caused by the first and the second prism separately. Based on these results, the system error of our prototype was estimated. The derived formulas can be implemented to evaluate beam directing errors of any Risley-prism beam directing system with a similar configuration. PMID:25607958

  10. Precambrian accretionary history and phanerozoic structures-A unified explanation for the tectonic architecture of the nebraska region, USA

    USGS Publications Warehouse

    Carlson, M.P.

    2007-01-01

    The Phanerozoic history in Nebraska and adjacent regions contains many patterns of structure and stratigraphy that can be directly related to the history of the Precambrian basement rocks of the area. A process is proposed that explains the southward growth of North America during the period 1.8-1.6 Ga. A series of families of accretionary events during the Proterozoic emplaced sutures that remained as fundamental basement weak zones. These zones were rejuvenated in response to a variety of continental stress events that occurred during the Phanerozoic. By combining the knowledge of basement history with the history of rejuvenation during the Phanerozoic, both the details of Proterozoic accretionary growth and an explanation for the patterns of Phanerozoic structure and stratigraphy is provided. ?? 2007 The Geological Society of America. All rights reserved.

  11. Stabilization of a self-referenced, prism-based, Cr:forsterite laser frequency comb using an intracavity prism

    SciTech Connect

    Tillman, Karl A.; Thapa, Rajesh; Knabe, Kevin; Wu Shun; Lim, Jinkang; Washburn, Brian R.; Corwin, Kristan L.

    2009-12-20

    The frequency comb from a prism-based Cr:forsterite laser has been frequency stabilized using intracavity prism insertion and pump power modulation. Absolute frequency measurements of a CW fiber laser stabilized to the P(13) transition of acetylene demonstrate a fractional instability of {approx}2x10{sup -11} at a 1 s gate time, limited by a commercial Global Positioning System (GPS)-disciplined rubidium oscillator. Additionally, absolute frequency measurements made simultaneously using a second frequency comb indicate relative instabilities of 3x10{sup -12} for both combs for a 1 s gate time. Estimations of the carrier-envelope offset frequency linewidth based on relative intensity noise and the response dynamics of the carrier-envelope offset to pump power changes confirm the observed linewidths.

  12. Spatial distribution of diverse cold seep communities living on various diapiric structures of the southern Barbados prism

    NASA Astrophysics Data System (ADS)

    Olu, K.; Sibuet, M.; Harmegnies, F.; Foucher, J.-P.; Fiala-Médioni, A.

    , both associated with sulfur-oxydizing bacteria, and there were numerous empty shells. The densities and biomasses of symbiotic bivalves were far greater in the area studied than in a deeper mud volcano field on the same prism that had been studied previously. This is consistent with a report that methane production is greater in the southern region of this accretionary prism than in the northern. Numerous non-symbiotic organisms were observed in and around the areas of the seeps, some are endemic to the seep communities, including some gastropods and shrimps, others are either colonists or vagrants from the surrounding deep-sea floor. Filter feeders were very abundant, and some of these, like the serpulids and large sponges, may also be dependent on the chemosynthetic production. Faunistic composition of both symbiotic and non-symbiotic taxa, of the assemblages around these cold seeps, is closely related to that reported for communities living on hydrocarbon seeps in the Gulf of Mexico.

  13. Forest Biomass Mapping from Prism Triplet, Palsar and Landsat Data

    NASA Astrophysics Data System (ADS)

    Ranson, J.; Sun, G.; Ni, W.

    2014-12-01

    The loss of sensitivity at higher biomass levels is a common problem in biomass mapping using optical multi-spectral data or radar backscattering data due to the lack of information on canopy vertical structure. Studies have shown that adding implicit information of forest vertical structure improves the performance of forest biomass mapping from optical reflectance and radar backscattering data. LiDAR, InSAR and stereo imager are the data sources for obtaining forest structural information. The potential of providing information on forest vertical structure by stereoscopic imagery data has drawn attention recently due to the availability of high-resolution digital stereo imaging from space and the advances of digital stereo image processing software. The Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM) onboard the Advanced Land Observation Satellite (ALOS) has acquired multiple global coverage from June 2006 to April 2011 providing a good data source for regional/global forest studies. In this study, five PRISM triplets acquired on June 14, 2008, August 19 and September 5, 2009; PALSAR dual-pol images acquired on July 12, 2008 and August 30, 2009; and LANDSAT 5 TM images acquired on September 5, 2009 and the field plot data collected in 2009 and 2010 were used to map forest biomass at 50m pixel in an area of about 4000 km2in Maine, USA ( 45.2 deg N 68.6 deg W). PRISM triplets were used to generate point cloud data at 2m pixel first and then the average height of points above NED (National Elevation Dataset) within a 50m by 50m pixel was calculated. Five images were mosaicked and used as canopy height information in the biomass estimation along with the PALSAR HH, HV radar backscattering and optical reflectance vegetation indices from L-5 TM data. A small portion of this region was covered by the Land Vegetation and Ice Sensor (LVIS) in 2009. The biomass maps from the LVIS data was used to evaluate the results from combined use of PRISM, PALSAR and

  14. An evaluation of factors influencing pore pressure in accretionary complexes: Implications for taper angle and wedge mechanics

    USGS Publications Warehouse

    Saffer, D.M.; Bekins, B.A.

    2006-01-01

    At many subduction zones, accretionary complexes form as sediment is off-scraped from the subducting plate. Mechanical models that treat accretionary complexes as critically tapered wedges of sediment demonstrate that pore pressure controls their taper angle by modifying basal and internal shear strength. Here, we combine a numerical model of groundwater flow with critical taper theory to quantify the effects of sediment and de??collement permeability, sediment thickness, sediment partitioning between accretion and underthrusting, and plate convergence rate on steady state pore pressure. Our results show that pore pressure in accretionary wedges can be viewed as a dynamically maintained response to factors which drive pore pressure (source terms) and those that limit flow (permeability and drainage path length). We find that sediment permeability and incoming sediment thickness are the most important factors, whereas fault permeability and the partitioning of sediment have a small effect. For our base case model scenario, as sediment permeability is increased, pore pressure decreases from near-lithostatic to hydrostatic values and allows stable taper angles to increase from ??? 2.5?? to 8??-12.5??. With increased sediment thickness in our models (from 100 to 8000 m), increased pore pressure drives a decrease in stable taper angle from 8.4??-12.5?? to 15?? to <4??) with increased sediment thickness (from <1 to 7 km). One key implication is that hydrologic properties may strongly influence the strength of the crust in a wide range of geologic settings. Copyright 2006 by the American Geophysical Union.

  15. Adult Learning Development from the Prism of Homestay

    ERIC Educational Resources Information Center

    Cyprian, Onwubiko Emeka

    2012-01-01

    This study seeks to understand how adult learning takes place in homestay programme at Kanchong Darat, Banting, and Selangor in Malaysia. The study seeks to provide an overview evaluation and some salient lessons that could be derived in providing quality homestay services to learners. More so, the study succinctly covers socio-cultural issues in…

  16. Contrasting décollement and prism properties over the Sumatra 2004-2005 earthquake rupture boundary.

    PubMed

    Dean, Simon M; McNeill, Lisa C; Henstock, Timothy J; Bull, Jonathan M; Gulick, Sean P S; Austin, James A; Bangs, Nathan L B; Djajadihardja, Yusuf S; Permana, Haryadi

    2010-07-01

    Styles of subduction zone deformation and earthquake rupture dynamics are strongly linked, jointly influencing hazard potential. Seismic reflection profiles across the trench west of Sumatra, Indonesia, show differences across the boundary between the major 2004 and 2005 plate interface earthquakes, which exhibited contrasting earthquake rupture and tsunami generation. In the southern part of the 2004 rupture, we interpret a negative-polarity sedimentary reflector approximately 500 meters above the subducting oceanic basement as the seaward extension of the plate interface. This predécollement reflector corresponds to unusual prism structure, morphology, and seismogenic behavior that are absent along the 2005 rupture zone. Although margins like the 2004 rupture zone are globally rare, our results suggest that sediment properties influence earthquake rupture, tsunami hazard, and prism development at subducting plate boundaries. PMID:20616276

  17. HFSE-rich picritic rocks from the Mino accretionary complex, southwestern Japan

    NASA Astrophysics Data System (ADS)

    Ichiyama, Yuji; Ishiwatari, Akira

    2005-06-01

    Sills, pillow lavas and hyaloclastites of the HFSE-rich picrite and related rocks (ankaramite and basanite) occur in the Middle Permian cherts in the Mino Jurassic accretionary complex, southwestern Japan. These rocks show systematic trace element patterns enriched in incompatible elements, which indicate that the associated ankaramite and basanite are formed by the crystal fractionation from the picrite. The presence of the hyaloclastite in the chert sequence covering a large tholeiitic greenstone body indicates that the picrite was produced in an intraoceanic setting in the Middle Permian time subsequent to the extrusion of the voluminous oceanic island tholeiite. The Mino picrites resemble the Siberian meimechite and Polynesian picrites in its HFSE-rich chemical composition. The HFSE enrichment in these picrites cannot be explained by low degree of partial melting of primitive peridotite mantle only, and needs a source material involving recycled oceanic crust (eclogite). The differences in MgO content and in TiO2/Al2O3 and Zr/Y ratios among the HFSE-rich picrites indicate that the melting pressure increases from the Polynesian picrite through Mino picrite to Siberian picrite. This may reflect the increasing thickness of the overlying lithosphere at the time and place of magmatism. The HFSE-rich picrites may be a product of a superplume event. The presence of HFSE-rich picrite in Mino and Siberia indicate that the superplume activities occur in both continental and oceanic settings in the Permian time.

  18. Falls Lake melange, a polydeformed accretionary complex in the North Carolina piedmont

    SciTech Connect

    Horton, J.W. Jr.; Blake, D.E.; Wylie, A.S. Jr.; Stoddard, E.F.

    1985-01-01

    The Falls Lake melange in the eastern Piedmont of North Carolina is composed of mafic and ultramafic blocks and pods of diverse shapes and sizes, from about 1 cm to 7 km in length, dispersed without stratigraphic continuity in a matrix of pelitic schist and metagraywacke. The melange lies between the Carolina slate belt on the west and the Raleigh belt on the east. This terrane has been mapped in detail from near Wilton in Granville County, southward for about 40 km to west Raleigh in Wake County. Preliminary petrologic and geochemical data suggest an oceanic crustal origin for the mafic and ultramafic inclusions. Although the lenticular shapes of most fragments are attributable to ductile deformation, a few more equant fragments that are clearly overprinted by the earliest recognized matrix schistosity have round to angular shapes resembling sedimentary clasts. These observations suggest formation by a combination of sedimentary and tectonic processes, perhaps in the accretionary wedge of a convergent plate margin. The Falls Lake melange and the overlying late Proterozoic to Early Cambrian volcanic-arc terrane of the accreted Carolina slate belt were thrust upon a probably continental terrane of the Raleigh belt before overprinting by late Paleozoic folding and metamorphism. The melange and its folded basal decollement are truncated on the east by a later fault of the Nutbush Creek system and have not been found east of this fault.

  19. Rock varnish in New York: An accelerated snapshot of accretionary processes

    NASA Astrophysics Data System (ADS)

    Krinsley, David H.; Dorn, Ronald I.; DiGregorio, Barry E.; Langworthy, Kurt A.; Ditto, Jeffrey

    2012-02-01

    Samples of manganiferous rock varnish collected from fluvial, bedrock outcrop and Erie Barge Canal settings in New York state host a variety of diatom, fungal and bacterial microbial forms that are enhanced in manganese and iron. Use of a Dual-Beam Focused Ion Beam Scanning Electron Microscope to manipulate the varnish in situ reveals microbial forms that would not have otherwise been identified. The relative abundance of Mn-Fe-enriched biotic forms in New York samples is far greater than varnishes collected from warm deserts. Moisture availability has long been noted as a possible control on varnish growth rates, a hypothesis consistent with the greater abundance of Mn-enhancing bioforms. Sub-micron images of incipient varnish formation reveal that varnishing in New York probably starts with the mortality of microorganisms that enhanced Mn on bare mineral surfaces; microbial death results in the adsorption of the Mn-rich sheath onto the rock in the form of filamentous networks. Clay minerals are then cemented by remobilization of the Mn-rich material. Thus, the previously unanswered question of what comes first - clay mineral deposition or enhancement of Mn - can be answered in New York because of the faster rate of varnish growth. In contrast, very slow rates of varnishing seen in warm deserts, of microns per thousand years, make it less likely that collected samples will reveal varnish accretionary processes than samples collected from fast-accreting moist settings.

  20. Hydrocarbon gas potential of accretionary melange terranes: an example from the olympic peninsula, Washington

    SciTech Connect

    Kvenvolden, K.A.; Snavely, P.D. Jr.

    1985-01-01

    Convergence between the oceanic and North American plates during middle late Eocene and late middle Miocene times produced two principal accretionary terranes of melange and broken formation on the continental margin of Washington. Hydrocarbon analyses of these melange units were undertaken to evaluate their source rock potential for oil and gas and to assess the generative processes operating in these thick melange wedges. The results of pyrolysis, vitrinite reflectance, and visual kerogen analyses of samples of these melanges are consistent and in good agreement, showing mainly Type III organic matter that is marginally mature to mature with respect to gas generation. Coastal exposure of Ozette melange commonly have a petroliferous odor which contains methane through at least the pentanes as prominent constitutents. Hydrocarbon gases from seeps and from an abandoned well in the study area have been molecular compositions and methane carbon isotopic values indicating related sources. The authors evidence suggest that the Ozette assemblage melange is the principal source for thermogenic hydrocarbon gases. Potential exploration targets may exist in western Washington where melange and broken formation are thrust beneath the Eocene oceanic crust (Crescent Formation). Gas generated from the underplated rocks could have migrated through the upper plate into structures in the Tertiary strata that overlie these Eocene basalts.

  1. Education through the prism of computation

    NASA Astrophysics Data System (ADS)

    Kaurov, Vitaliy

    2014-03-01

    With the rapid development of technology, computation claims its irrevocable place among research components of modern science. Thus to foster a successful future scientist, engineer or educator we need to add computation to the foundations of scientific education. We will discuss what type of paradigm shifts it brings to these foundations on the example of Wolfram Science Summer School. It is one of the most advanced computational outreach programs run by Wolfram Foundation, welcoming participants of almost all ages and backgrounds. Centered on complexity science and physics, it also covers numerous adjacent and interdisciplinary fields such as finance, biology, medicine and even music. We will talk about educational and research experiences in this program during the 12 years of its existence. We will review statistics and outputs the program has produced. Among these are interactive electronic publications at the Wolfram Demonstrations Project and contributions to the computational knowledge engine Wolfram|Alpa.

  2. Nicotine addiction through a neurogenomic prism

    PubMed Central

    Caron, Lorraine; Karkazis, Katrina; Raffin, Thomas A.; Swan, Gary; Koenig, Barbara A.

    2008-01-01

    Studies are under way to examine the neurogenetic factors contributing to smoking behaviors. The combined approaches of genomics, molecular biology, neuroscience, and pharmacology are expected to fuel developments in pharmacogenetics, to create new genetic tests, and ultimately to provide the basis for innovative strategies for smoking cessation and prevention. The emergence of a neurogenomic understanding of nicotine addiction is likely to induce fundamental changes in popular, clinical, and public health views of smoking, which could significantly shape existing practices and policies to reduce tobacco use. Still a nascent area of research, nicotine addiction provides an excellent case study through which to anticipate key ethical and policy issues in both behavioral genetics and the neurogenomics of addictive behaviors. PMID:16036275

  3. Inventory and Review of Existing PRISM Hydrogeologic Data for the Islamic Republic of Mauritania, Africa

    USGS Publications Warehouse

    Friedel, Michael J.

    2008-01-01

    The USGS entered into an agreement with the Mauritania Ministry of Mines and Industry to inventory and review the quality of information collected as part of the Project for Strengthening of the Institutions in the Mining Sector (PRISM). Whereas the PRISM program collected geophysical, geochemical, geological, satellite, and hydrogeologic information, this report focuses on an inventory and review of available hydrogeologic data provided to the USGS in multiple folders, files, and formats. Most of the information pertained to the hydrogeologic setting and the water budget of evaporation, evapotranspiration, and precipitation in the Choum-Zouerate area in northwestern Mauritania, and the country of Mauritania itself. Other information about the quantity and quality of groundwater was found in the relational Access database. In its present form, the limited hydrogeologic information was not amenable to conducting water balance, geostatistical, and localized numerical modeling studies in support of mineral exploration and development. Suggestions are provided to remedy many of the data's shortcomings, such as performing quality assurance on all SIPPE2 data tables and sending questionnaires to appropriate agencies, mining and other companies to populate the database with additional meteorology, hydrology, and groundwater data.

  4. Calibration of miniature prism-based stereoscopic imagers for precise spatial measurements

    NASA Astrophysics Data System (ADS)

    Machikhin, Alexander S.; Gorevoy, Alexey V.

    2016-04-01

    The paper is targeted to find the optimal mathematical model and the calibration algorithm for the industrial endoscope equipped with the prism-based attachable stereo adapter, which allows imaging from two different points by a single sensor. We consider the conventional calibration methods for the pinhole camera model with polynomial distortion approximation and compared them with the ray tracing model based on the vector form of Snell's law. In order to evaluate each of the proposed models we have developed the software for the imitation of various calibration procedures using different types of calibration targets. We use the computer simulation to prove that the pinhole camera models, widely used in machine vision, are very limited for describing prism-based endoscopic measurement systems. Our analysis identified the main problems for these models, such as entrance pupil shift, non-homocentric beams and required number of coefficients for polynomial models and the iterative forward ray aiming for the ray-tracing model. The proposed technique is flexible and can also be used to test stability and convergence of the parameter estimation procedures and to compare calibration targets and strategies.

  5. Ferromanganese nodules from MANOP Sites H, S, and R-Control of mineralogical and chemical composition by multiple accretionary processes

    USGS Publications Warehouse

    Dymond, J.; Lyle, M.; Finney, B.; Piper, D.Z.; Murphy, K.; Conard, R.; Pisias, N.

    1984-01-01

    The chemical composition of ferromanganese nodules from the three nodule-bearing MANOP sites in the Pacific can be accounted for in a qualitative way by variable contributions of distinct accretionary processes. These accretionary modes are: 1. (1) hydrogenous, i.e., direct precipitation or accumulation of colloidal metal oxides in seawater, 2. (2) oxic diagenesis which refers to a variety of ferromanganese accretion processes occurring in oxic sediments; and 3. (3) suboxic diagenesis which results from reduction of Mn+4 by oxidation of organic matter in the sediments. Geochemical evidence suggests processes (1) and (2) occur at all three MANOP nodule-bearing sites, and process (3) occurs only at the hemipelagic site, H, which underlies the relatively productive waters of the eastern tropical Pacific. A normative model quantitatively accounts for the variability observed in nearly all elements. Zn and Na, however, are not well explained by the three end-member model, and we suggest that an additional accretionary process results in greater variability in the abundances of these elements. Variable contributions from the three accretionary processes result in distinct top-bottom compositional differences at the three sites. Nodule tops from H are enriched in Ni, Cu, and Zn, instead of the more typical enrichments of these elements in nodule bottoms. In addition, elemental correlations typical of most pelagic nodules are reversed at site H. The three accretionary processes result in distinct mineralogies. Hydrogenous precipitation produces ??MnO2. Oxic diagenesis, however, produces Cu-Ni-rich todorokite, and suboxic diagenesis results in an unstable todorokite which transforms to a 7 A?? phase ("birnessite") upon dehydration. The presence of Cu and Ni as charge-balancing cations influence the stability of the todorokite structure. In the bottoms of H nodules, which accrete dominantly by suboxic diagenesis, Na+ and possibly Mn+2 provide much of the charge balance for

  6. Asymmetric transmission in prisms using structures and materials with isotropic-type dispersion.

    PubMed

    Gundogdu, Funda Tamara; Serebryannikov, Andriy E; Cakmak, A Ozgur; Ozbay, Ekmel

    2015-09-21

    It is demonstrated that strong asymmetry in transmission can be obtained at the Gaussian beam illumination for a single prism based on a photonic crystal (PhC) with isotropic-type dispersion, as well as for its analog made of a homogeneous material. Asymmetric transmission can be realized with the aid of refraction at a proper orientation of the interfaces and wedges of the prism, whereas neither contribution of higher diffraction orders nor anisotropic-type dispersion is required. Furthermore, incidence toward a prism wedge can be used for one of two opposite directions in order to obtain asymmetry. Thus, asymmetric transmission is a general property of the prism configurations, which can be obtained by using simple geometries and quite conventional materials. The obtained results show that strong asymmetry can be achieved in PhC prisms with (nearly) circular shape of equifrequency dispersion contours, in both cases associated with the index of refraction 01. For the comparison purposes, results are also presented for solid uniform non-magnetic prisms made of a material with the same value of n. It is shown in zero-loss approximation that the PhC prism and the ultralow-index material prism (0prism and the solid dielectric prism can show the same scenario at n>1. Possible contributions of scattering on the individual rods and diffraction on the wedge to the resulting mechanism are discussed. Analogs of unidirectional splitting and unidirectional deflection regimes, which are known from the studies of PhC gratings, are obtained in PhC prisms and solid uniform prisms, i.e. without higher diffraction orders. PMID:26406618

  7. Separation of multiple images via directional guidance using structured prism and pyramid arrays.

    PubMed

    Lee, Hyemin; Seo, Hyein; Kang, Sunghwan; Yoon, Hyunsik

    2016-09-01

    We propose a new concept of separating images through a directional guide of multi-visuals by using structured prism or pyramid arrays. By placing prism arrays onto two different image arrays, the two collective images below the facets are guided to different directions. Using optical calculations, we identify a condition for successful image separation. Transparent pyramid arrays are used to separate four images into four directions. The direction of refracted rays can be controlled by the refractive index of prisms and liquid filled into the voids. In addition, the images can be switched by stretching and releasing an elastomeric prism array. PMID:27607698

  8. Closed form analytical inverse solutions for Risley-prism-based beam steering systems in different configurations.

    PubMed

    Li, Yajun

    2011-08-01

    Nonparaxial ray tracing through Risley prisms of four different configurations is performed to give the exact solution of the inverse problem arisen from applications of Risley prisms to free space communications. Predictions of the exact solution and the third-order theory [Appl. Opt. 50, 679 (2011)] are compared and results are shown by curves for systems using prisms of different materials. The exact solution for the problem of precision pointing is generalized to investigate the synthesis of the scan pattern, i.e., to create a desirable scan pattern on some plane perpendicular to the optical axis of the system by controlling the circular motion of the two prisms. PMID:21833103

  9. Ray-optical negative refraction and pseudoscopic imaging with Dove-prism arrays

    NASA Astrophysics Data System (ADS)

    Courtial, Johannes; Nelson, John

    2008-02-01

    A sheet consisting of an array of small, aligned Dove prisms can locally (on the scale of the width of the prisms) invert one component of the ray direction. A sandwich of two such Dove-prism sheets that inverts both transverse components of the ray direction is a ray-optical approximation to the interface between two media with refractive indices +n and n. We demonstrate the simulated imaging properties of such a Dove-prism-sheet sandwich, including a demonstration of pseudoscopic imaging.

  10. Simulation of electrowetting lens and prism arrays for wavefront compensation.

    PubMed

    Gopinath, Juliet T; Bright, Victor M; Cogswell, Carol C; Niederriter, Robert D; Watson, Alexander; Zahreddine, Ramzi; Cormack, Robert H

    2012-09-20

    A novel application of electrowetting devices has been simulated: wavefront correction using an array of electrowetting lenses and prisms. Five waves of distortion can be corrected with Strehl ratios of 0.9 or higher, utilizing piston, tip-tilt, and curvature corrections from arrays of 19 elements and fill factors as low as 40%. Effective control of piston can be achieved by placing the liquid lens array at the focus of two microlens arrays. Seven waves of piston delay can be generated with variation in focal length between 1.5 and 500 mm. PMID:23033033

  11. Ultrafine Metal-Organic Right Square Prism Shaped Nanowires.

    PubMed

    Otake, Ken-Ichi; Otsubo, Kazuya; Sugimoto, Kunihisa; Fujiwara, Akihiko; Kitagawa, Hiroshi

    2016-05-23

    We report the structural design and control of electronic states of a new series of ultrafine metal-organic right square prism-shaped nanowires. These nanowires have a very small inner diameter of about 2.0 Å, which is larger than hydrogen and similar to xenon atomic diameters. The electronic states of nanowires can be widely controlled by substitution of structural components. Moreover, the platinum homometallic nanowire shows a 100 times higher proton conductivity than a palladium/platinum heterometallic one depending on the electronic states. PMID:27080935

  12. Sealed One Piece Battery Having A Prism Shape Container

    DOEpatents

    Verhoog, Roelof; Barbotin, Jean-Loup

    2000-03-28

    A sealed one-piece battery having a prism-shaped container including: a tank consisting of a single plastic material, a member fixed and sealed to the tank and to partitions on the side of the tank opposite the transverse wall to seal the tank, two flanges fixed and sealed to longitudinal walls defining flow compartments for a heat-conducting fluid, and two tubes on the transverse wall of the tank forming an inlet and an outlet for fluid common to the compartments.

  13. An objective prism survey of emission line galaxies

    NASA Astrophysics Data System (ADS)

    Liu, J.-Y.; Huang, Y.-W.; Feng, X.-C.

    1986-09-01

    The first list of emission line objects detected as part of an object prism survey of emission line galaxies begun in China in 1981 is presented. The instrument and observations are described, and the identification of emission-line galaxies is discussed. The spectral structural classification of the presented objects is addressed. On a dozen plates covering some 220 square degrees of sky, 50 emission line objects were detected, 47 of which are galaxies and the other three of which are planetary nebulae. Finding charts of the objects are presented.

  14. Topological relations embodied in a generalized tri-prism (GTP) model for a 3D geoscience modeling system

    NASA Astrophysics Data System (ADS)

    Wu, Lixin

    2004-05-01

    3D geoscience modeling system (3D GMS) embodied with topological relations is of extreme importance for Geosciences. This paper presents a universal 3D model, generalized tri-prism (GTP) for 3D GMS and real-3D GIS, which is a modification and improvement of former presented analogous tri-prism (ATP) model and is the common model of pyramid model, tetrahedron model and tri-prism (TP) model. The GTP model takes the divergent drill holes, rather than triangulation network after interpolation or vertical parallel drill holes after projection transformation, as its direct data source. Hence, the reliability and quality of the 3D model is maximatily ensured. The GTP component is comprised of six primitives as node, TIN-edge, side-edge, TIN-face, side-face and GTP. Besides, three intermediary diagonal lines in each GTP component are temporary applied for spatial operations. Six groups of topological relations between the six primitives are carefully designed for geo-spatial inquiry and geo-spatial analysis. The mechanisms of chipping, dynamic updating and local refining operations of so constructed 3D geological model are introduced. A real-3D software platform, GeoMo 3D@, developed with VC ++, OPGL and SQL server, demonstrates most of the 3D geo-spatial operations including clipping, separating, uncovering and geo-fence diagram generating based on an actual 3D geological model of a coal mine, Tangshan, P.R. China.

  15. A Pilot Study of Perceptual-Motor Training for Peripheral Prisms

    PubMed Central

    Houston, Kevin E.; Bowers, Alex R.; Fu, Xianping; Liu, Rui; Goldstein, Robert B.; Churchill, Jeff; Wiegand, Jean-Paul; Soo, Tim; Tang, Qu; Peli, Eli

    2016-01-01

    Purpose Peripheral prisms (p-prisms) shift peripheral portions of the visual field of one eye, providing visual field expansion for patients with hemianopia. However, patients rarely show adaption to the shift, incorrectly localizing objects viewed within the p-prisms. A pilot evaluation of a novel computerized perceptual-motor training program aiming to promote p-prism adaption was conducted. Methods Thirteen patients with hemianopia fitted with 57Δ oblique p-prisms completed the training protocol. They attended six 1-hour visits reaching and touching peripheral checkerboard stimuli presented over videos of driving scenes while fixating a central target. Performance was measured at each visit and after 3 months. Results There was a significant reduction in touch error (P = 0.01) for p-prism zone stimuli from pretraining median of 16.6° (IQR 12.1°–19.6°) to 2.7° ( IQR 1.0°–8.5°) at the end of training. P-prism zone reaction times did not change significantly with training (P > 0.05). P-prism zone detection improved significantly (P = 0.01) from a pretraining median 70% (IQR 50%–88%) to 95% at the end of training (IQR 73%–98%). Three months after training improvements had regressed but performance was still better than pretraining. Conclusions Improved pointing accuracy for stimuli detected in prism-expanded vision of patients with hemianopia wearing 57Δ oblique p-prisms is possible and training appears to further improve detection. Translational Relevance This is the first use of this novel software to train adaptation of visual direction in patients with hemianopia wearing peripheral prisms. PMID:26933522

  16. Kinematic markers dissociate error correction from sensorimotor realignment during prism adaptation.

    PubMed

    O'Shea, Jacinta; Gaveau, Valérie; Kandel, Matthieu; Koga, Kazuo; Susami, Kenji; Prablanc, Claude; Rossetti, Yves

    2014-03-01

    This study investigated the motor control mechanisms that enable healthy individuals to adapt their pointing movements during prism exposure to a rightward optical shift. In the prism adaptation literature, two processes are typically distinguished. Strategic motor adjustments are thought to drive the pattern of rapid endpoint error correction typically observed during the early stage of prism exposure. This is distinguished from so-called 'true sensorimotor realignment', normally measured with a different pointing task, at the end of prism exposure, which reveals a compensatory leftward 'prism after-effect'. Here, we tested whether each mode of motor compensation - strategic adjustments versus 'true sensorimotor realignment' - could be distinguished, by analyzing patterns of kinematic change during prism exposure. We hypothesized that fast feedforward versus slower feedback error corrective processes would map onto two distinct phases of the reach trajectory. Specifically, we predicted that feedforward adjustments would drive rapid compensation of the initial (acceleration) phase of the reach, resulting in the rapid reduction of endpoint errors typically observed early during prism exposure. By contrast, we expected visual-proprioceptive realignment to unfold more slowly and to reflect feedback influences during the terminal (deceleration) phase of the reach. The results confirmed these hypotheses. Rapid error reduction during the early stage of prism exposure was achieved by trial-by-trial adjustments of the motor plan, which were proportional to the endpoint error feedback from the previous trial. By contrast, compensation of the terminal reach phase unfolded slowly across the duration of prism exposure. Even after 100 trials of pointing through prisms, adaptation was incomplete, with participants continuing to exhibit a small rightward shift in both the reach endpoints and in the terminal phase of reach trajectories. Individual differences in the degree of

  17. Headless submarine canyons and fluid flow on the toe of the Cascadia accretionary complex

    USGS Publications Warehouse

    Orange, D.L.; McAdoo, B.G.; Moore, J.C.; Tobin, H.; Screaton, E.; Chezar, H.; Lee, H.; Reid, M.; Vail, R.

    1997-01-01

    Headless submarine canyons with steep headwalls and shallowly sloping floors occur on both the second and third landward vergent anticlines on the toe of the Cascadia accretionary complex off central Oregon (45 ??N, 125?? 30??W). In September 1993, we carried out a series of nine deep tow camera sled runs and nine ALVIN dives to examine the relationship between fluid venting, structure and canyon formation. We studied four canyons on the second and third landward vergent anticlines, as well as the apparently unfailed intercanyon regions along strike. All evidence of fluid expulsion is associated with the canyons; we found no evidence of fluid flow between canyons. Even though all fluid seeps are related to canyons, we did not find seeps in all canyons, and the location of the seeps within the canyons differed. On the landward facing limb of the second landward vergent anticline a robust cold seep community occurs at the canyon's inflection point. This seep is characterized by chemosynthetic vent clams, tube worms and extensive authigenic carbonate. Fluids for this seep may utilize high-permeability flow paths either parallel to bedding within the second thrust ridge or along the underlying thrust fault before leaking into the overriding section. Two seaward facing canyons on the third anticlinal ridge have vent clam communities near the canyon mouths at approximately the intersection between the anticlinal ridge and the adjacent forearc basin. No seeps were found along strike at the intersection of the slope basin and anticlinal ridge. We infer that the lack of seepage along strike and the presence of seeps in canyons may be related to fluid flow below the forearc basin/slope unconformity (overpressured by the impinging thrust fault to the west?) directed toward canyons at the surface.

  18. Accretionary Complex Origin of the Mafic-ultramafic Bodies of the Sanbagawa Belt, Central Shikoku, Japan

    NASA Astrophysics Data System (ADS)

    Terabayashi, M.; Okamoto, K.; Yamamoto, H.; Kaneko, Y.; Ota, T.; Maruyama, S.; Katayama, I.; Komiya, T.; Anma, R.; Ozawa, H.; Windley, B. F.; Liou, J. G.

    2004-12-01

    In the high-grade Cretaceous Sanbagawa high pressure (HP) metamorphic belt our new 1:5000 scale mapping of the eclogitic mafic-ultramafic bodies and their surrounding epidote-amphibolite-facies schists, has revealed a duplex structure formed by the subduction of the Izanagi-Pacific oceanic plate. Lithologies of the two largest mafic-ultramafic bodies in the Sanbagawa belt, the Iratsu eclogite and the Higashi-Akaishi peridotite, strike WNW-ESE and dip N; the upper boundary with the surrounding schist is a normal fault, whereas the lower boundary is a thrust. The Iratsu body is subdivided into at least two tectonic units; the unit boundary is sub-parallel to a lithological boundary. The protoliths of the upper unit are gabbro, basalt, minor quartz rock and pelite, and those of the lower unit are pyroxenite, gabbro, basalt, chert and marble, in ascending order. The lower unit is characterized by layers of alternating eclogitic metagabbro and pyroxenite. The layers are extensive at the bottom of the Iratsu eclogite, and transient towards the Higashi-Akaishi body. Eclogite-facies metapsammite is intercalated between the Iratsu and Higashi-Akaishi bodies. Our mapping has revealed the following; (1) a duplex structure of the mafic-ultramafic bodies indicating their accretionary complex origin. (2) Reconstructed oceanic plate stratigraphy in ascending order of peridotite, gabbro, basalt, limestone, minor chert and pelite suggests that different parts of the protolith were derived from a mid-oceanic topographic high, an oceanic island or plateau, and an overlying trench turbidite. (3) The convergent motion of the oceanic plate changed from NW to NE during the accretion of the large oceanic island or plateau.

  19. Detrital zircon geochronology and provenance analysis applied to the onshore Makran accretionary wedge, SE Iran

    NASA Astrophysics Data System (ADS)

    Mohammadi, A.; Burg, J.; Winkler, W.; Ruh, J. B.; Von Quadt, A.

    2013-12-01

    The Makran is one of the largest accretionary wedges in the world, located in Southeast Iran. The Makran Basin is composed of turbidity sediments ranging in age from late Cretaceous to Holocene. The analysis of detrital zircons is important to interpret the provenance of the sediments and to clarify the geological history of the sedimentary basins and their surrounding source regions. We present about 2777 new U-Pb ages (ICP laser ablation mass spectrometry) from individual detrital zircons of 18 sandstone samples collected throughout the onshore Makran. 101 detrital zircon ages from a late Cretaceous fine grained sandstone ranges from 180-160 Ma (Mid-Jurassic). 478 detrital zircon ages obtained from the mid to late Eocene sandstone reveals different sources for the NE and NW parts of the Makran Basin. Zircon grains in the NE basin belong to two populations peaked at Mid-Jurassic and Mid-Eocene, with the noticeable absence of Cretaceous grains. In the NW basin, detrital zircons are Mid-Cretaceous to Mid-Eocene. 587 detrital zircon grains from fine to medium grained Oligocene sandstones collected in different parts of the basin range from Mid-Cretaceous to Mid-Eocene. 1611 detrital zircon age from Early Miocene sandstones collected in the eastern and western parts of the basin show distinctly different detrital zircon ages. They range from Mid-Cretaceous to Mid-Eocene in the eastern basin, from Late Cretaceous to Mid-Eocene in the west. Detrital zircon ages from Mid and Late Miocene sandstones rang from Late Cretaceous to Mid-Eocene. These new detrital zircon U-Pb age data show that the eastern and western parts of the Makran Basin received sediments from different source areas during Eocene and Early Miocene times. Mid and Late Miocene sediment are recycled (cannibalism) from the Oligocene units of the basin.

  20. Insights on deep, accretionary subduction processes from the Sistan ophiolitic "mélange" (Eastern Iran)

    NASA Astrophysics Data System (ADS)

    Angiboust, S.; Agard, P.; De Hoog, J. C. M.; Omrani, J.; Plunder, A.

    2013-01-01

    The Sistan ophiolitic belt, formed by the closure of the N-S trending Sistan Ocean during late Cretaceous times, comprises several branches and basins across a 100 × 700 km area along the Iran-Afghanistan border. One of these, the Ratuk complex, exposes disrupted HP ophiolitic blocks from a paleo-subduction complex generally interpreted as a tectonic "mélange". In order to better understand its overall structure and evaluate the degree of mixing within this mélange, an extensive set of serpentinized peridotites, mafic rocks and metasediments was collected in the Sulabest area (Ratuk complex). A detailed geological and structural map of the Sulabest area is herein provided, in which three main units (the Western, Upper and Eclogitic Units) separated by relatively sharp tectonic contacts were identified. The latter two of these slices exhibit metamorphic evidence for burial along the same HP-LT gradient (up to blueschist and eclogite facies, respectively). Sharp differences in peak metamorphic conditions and retrograde parageneses nevertheless suggest that they followed two distinct P-T trajectories. Geochemical signatures of ultramafic rocks indicate an abyssal origin for the non-metamorphic Western Unit while the presence of mantle wedge serpentinites is inferred for some samples from the high-pressure units. The differences in peak temperatures (between 520 and 650 °C) and the geochemical heterogeneity of mafic rocks suggest that tectonic mixing occurred (only) within the high-pressure units, possibly within the hydrated mantle wedge. Our results show that this portion of the Sistan ophiolitic belt did not form, as earlier proposed, by chaotic tectonic "mélange" (i.e. where small tectonic blocks with distinct P-T histories are mixed in a mechanically weak matrix). We instead propose that this segment of the ophiolitic belt formed via accretionary processes deep in the subduction zone, whereby distinct slices with different P-T histories were tectonically

  1. Spectra of Eta Carina from Objective Prism Photographic Plates

    NASA Astrophysics Data System (ADS)

    Cline, J. Donald; Castelaz, M.; Barker, T.

    2008-05-01

    Brightness and spectral variations of Eta Carina occur over a 5.5 year cycle. Emission lines were observed to fade in 1948, 1962, 1981, 1987, and 1992 (Damineli 1996, ApJ, 460, L49), and 1997 (Eta Carinae at the Millennium, ASP Conf. Ser. 179, ed. J.A. Morse, R.M. Humphreys, and A. Damineli). Gaps in the observation of spectra occur in 1970 and 1975 when two other such occurrences of the 5.5 year cycle were expected. Objective prism photographic plates of Eta Carina were found in the Astronomical Photographic Data Archive located at Pisgah Astronomical Research Institute. The plates belong to the University of Michigan survey (Houk 1978, Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars). One plate, IN emulsion + RG1 filter, was taken on 1968 July 4 UT. The other plate, IIaO emulsion, was taken on 1972 March 12 UT. These plates were taken between the 5.5 year cyclic events of 1970 and 1975 and therefore represent the usual emission line spectra. The spectrum of Eta Car was extracted from each of the objective prism plates and will be presented.

  2. Generation of High Resolution Global DSM from ALOS PRISM

    NASA Astrophysics Data System (ADS)

    Takaku, J.; Tadono, T.; Tsutsui, K.

    2014-04-01

    Panchromatic Remote-sensing Instrument for Stereo Mapping (PRISM), one of onboard sensors carried on the Advanced Land Observing Satellite (ALOS), was designed to generate worldwide topographic data with its optical stereoscopic observation. The sensor consists of three independent panchromatic radiometers for viewing forward, nadir, and backward in 2.5 m ground resolution producing a triplet stereoscopic image along its track. The sensor had observed huge amount of stereo images all over the world during the mission life of the satellite from 2006 through 2011. We have semi-automatically processed Digital Surface Model (DSM) data with the image archives in some limited areas. The height accuracy of the dataset was estimated at less than 5 m (rms) from the evaluation with ground control points (GCPs) or reference DSMs derived from the Light Detection and Ranging (LiDAR). Then, we decided to process the global DSM datasets from all available archives of PRISM stereo images by the end of March 2016. This paper briefly reports on the latest processing algorithms for the global DSM datasets as well as their preliminary results on some test sites. The accuracies and error characteristics of datasets are analyzed and discussed on various fields by the comparison with existing global datasets such as Ice, Cloud, and land Elevation Satellite (ICESat) data and Shuttle Radar Topography Mission (SRTM) data, as well as the GCPs and the reference airborne LiDAR/DSM.

  3. Portable digital micromirror device projector using a prism

    NASA Astrophysics Data System (ADS)

    Pan, Jui-Wen; Wang, Chih-Ming; Sun, Wen-Shing; Chang, Jenq-Yang

    2007-08-01

    A newly designed ultrasmall total internal reflection prism with a size of 29 mm×22 mm×24 mm and weight of 19.5 g is proposed for use in a pocket-sized Digital Micromirror Device projector. The entire projector, including an arc lamp illumination, relay, and projection system, has a height of 48 mm and a footprint of 80 mm×132 mm. By using an overdriving f/2.0 projection lens, the geometric efficiency of the projection system, ηgeo-pro, can be enhanced from 80% to 92%. Although, at the same time, the contrast decreased from 1200:1 to 500:1, this can be enhanced using an off-axis stop. By tuning the position of the stop, the contrast can be as high as 3700:1 for a ηgeo-pro equal to 90%. Using what we believe to be a novel prism design, we can get a very compact optical system with a high efficiency and good contrast ratio.

  4. Portable digital micromirror device projector using a prism.

    PubMed

    Pan, Jui-Wen; Wang, Chih-Ming; Sun, Wen-Shing; Chang, Jenq-Yang

    2007-08-01

    A newly designed ultrasmall total internal reflection prism with a size of 29 mm x 22 mm x 24 mm and weight of 19.5 g is proposed for use in a pocket-sized Digital Micromirror Device projector. The entire projector, including an arc lamp illumination, relay, and projection system, has a height of 48 mm and a footprint of 80 mm x 132 mm. By using an overdriving f/2.0 projection lens, the geometric efficiency of the projection system, eta(geo-pro), can be enhanced from 80% to 92%. Although, at the same time, the contrast decreased from 1200:1 to 500:1, this can be enhanced using an off-axis stop. By tuning the position of the stop, the contrast can be as high as 3700:1 for a eta(geo-pro) equal to 90%. Using what we believe to be a novel prism design, we can get a very compact optical system with a high efficiency and good contrast ratio. PMID:17676119

  5. Hierarchically triangular prism structured Co3O4: Self-supported fabrication and photocatalytic property

    EPA Science Inventory

    The formation of ammonium cobalt (II) phosphate was utilized to synthesize unprecedented 3D structures of Co3O4, triangular prisms and trunk-like structures, via a self-supported and organics-free method. The length of a triangular side of the prepared 3D triangular prisms is ~1...

  6. Prism Foil from an LCD Monitor as a Tool for Teaching Introductory Optics

    ERIC Educational Resources Information Center

    Planinsic, Gorazd; Gojkosek, Mihael

    2011-01-01

    Transparent prism foil is part of a backlight system in LCD monitors that are widely used today. This paper describes the optical properties of the prism foil and several pedagogical applications suitable for undergraduate introductory physics level. Examples include experiments that employ refraction, total internal reflection, diffraction and…

  7. Investigating First Year Elementary Mathematics Teacher Education Students' Knowledge of Prism

    ERIC Educational Resources Information Center

    Bozkurt, Ali; Koc, Yusuf

    2012-01-01

    The purpose of this study was to investigate first year elementary mathematics teacher education students' knowledge of prism. For this goal, the participants were asked to define the geometric concept of prism. The participants were 158 first year elementary mathematics teacher education students from a public university in Southern Turkey. The…

  8. Standardization of motion sickness induced by left-right and up-down reversing prisms

    NASA Technical Reports Server (NTRS)

    Reschke, M. F.; Vanderploeg, J. M.; Brumley, E. A.; Kolafa, J. J.; Wood, S. J.

    1990-01-01

    Reversing prisms are known to produce symptoms of motion sickness, and have been used to provide a chronic stimulus for training subjects on symptom recognition and regulation. However, testing procedures with reversing prisms have not been standardized. A set of procedures were evaluated which could be standardized using prisms for provocation and to compare the results between Right/Left Reversing Prisms (R/L-RP) and Up/Down Reversing Prisms (U/D-RP). Fifteen subjects were tested with both types of prisms using a self paced walking course throughout the laboratory with work stations established at specified intervals. The work stations provided tasks requiring eye-hand-foot coordination and various head movements. Comparisons were also made between these prism tests and two other standardized susceptibility tests, the KC-135 parabolic static chair test and the Staircase Velocity Motion Test (SVMT). Two different types of subjective symptom reports were compared. The R/L-RP were significantly more provocative than the U/D-RP. The incidence of motion sickness symptoms for the R/L-RP was similar to the KC-135 parabolic static chair test. Poor correlations were found between the prism tests and the other standardized susceptibility tests, which might indicate that different mechanisms are involved in provoking motion sickness for these different tests.

  9. Electron sharing and anion-π recognition in molecular triangular prisms.

    PubMed

    Schneebeli, Severin T; Frasconi, Marco; Liu, Zhichang; Wu, Yilei; Gardner, Daniel M; Strutt, Nathan L; Cheng, Chuyang; Carmieli, Raanan; Wasielewski, Michael R; Stoddart, J Fraser

    2013-12-01

    Stacking on a full belly: Triangular molecular prisms display electron sharing among their triangularly arranged naphthalenediimide (NDI) redox centers. Their electron-deficient cavities encapsulate linear triiodide anions, leading to the formation of supramolecular helices in the solid state. Chirality transfer is observed from the six chiral centers of the filled prisms to the single-handed helices. PMID:24227594

  10. X-ray refractive large aperture rolled prism lenses as condensers for x-ray tubes

    NASA Astrophysics Data System (ADS)

    Vogt, H.; Simon, M.; Last, A.; Marschall, F.; Mohr, J.; Nazmov, V.; Eisenhower, R.; Mettendorf, K. U.

    2011-10-01

    At the Institute of Microstructure Technology (IMT) at Karlsruhe Institute of Technology (KIT), refractive X-ray optics are developed. These optics are proposed to be used as condenser optics in X-Ray spectroscopy and microscopy applications with an X-ray tube as a source. To produce the lenses, a thin structured foil with equidistant fins in triangular form is casted from a structured silicon wafer. The foil is then wound around a glass fibre core. Due to this fabrication method, it is possible to produce large-aperture lenses with low absorption in comparison to other types of refractive X-Ray optics, like X-ray lenses with continuous parabolic shape or prism lenses. The first are limited due to their absorption while the latter are limited due to their mechanical stability of the prism columns. The optimisation of the so called X-Ray rolled prism lenses (RXPL) is underway at the institute and involves several parameters. One important property of the lenses is the correct form of the wound foil layers. This determines the number of necessary refractive elements at a given radius, which in turn determines the refracted slope and focal position of the transmitted beam. The spatial extent of the x-ray source is also being accounted for in the lens design. Another important point is the diameter of the winding core, which should be as small as possible due to the fact that the winding core reduces the active area of the lens. The rolling process itself is also revised to produce lenses with the above-mentioned small diameter winding cores and bend foil layers while sustaining a tight- fitting foil bundle. The lenses are studied at different energies and types of X-Ray tubes, as well as synchrotron sources, to gain additional information of the internal structure of the lens after the winding process. In this paper the current status of the lens development and results at X-Ray tube sources for use in diffractometers is presented.

  11. Pointing error analysis of Risley-prism-based beam steering system.

    PubMed

    Zhou, Yuan; Lu, Yafei; Hei, Mo; Liu, Guangcan; Fan, Dapeng

    2014-09-01

    Based on the vector form Snell's law, ray tracing is performed to quantify the pointing errors of Risley-prism-based beam steering systems, induced by component errors, prism orientation errors, and assembly errors. Case examples are given to elucidate the pointing error distributions in the field of regard and evaluate the allowances of the error sources for a given pointing accuracy. It is found that the assembly errors of the second prism will result in more remarkable pointing errors in contrast with the first one. The pointing errors induced by prism tilt depend on the tilt direction. The allowances of bearing tilt and prism tilt are almost identical if the same pointing accuracy is planned. All conclusions can provide a theoretical foundation for practical works. PMID:25321377

  12. ePRISM: A case study in multiple proxy and mixed temporal resolution integration

    USGS Publications Warehouse

    Robinson, Marci M.; Dowsett, Harry J.

    2010-01-01

    As part of the Pliocene Research, Interpretation and Synoptic Mapping (PRISM) Project, we present the ePRISM experiment designed I) to provide climate modelers with a reconstruction of an early Pliocene warm period that was warmer than the PRISM interval (similar to 3.3 to 3.0 Ma), yet still similar in many ways to modern conditions and 2) to provide an example of how best to integrate multiple-proxy sea surface temperature (SST) data from time series with varying degrees of temporal resolution and age control as we begin to build the next generation of PRISM, the PRISM4 reconstruction, spanning a constricted time interval. While it is possible to tie individual SST estimates to a single light (warm) oxygen isotope event, we find that the warm peak average of SST estimates over a narrowed time interval is preferential for paleoclimate reconstruction as it allows for the inclusion of more records of multiple paleotemperature proxies.

  13. A unit structure Rochon prism based on the extraordinary refraction of uniaxial birefringent crystals.

    PubMed

    Wu, Wendi; Wu, Fuquan; Shi, Meng; Su, Fufang; Han, Peigao; Ma, Lili

    2013-06-01

    Based on the Fermat's principle, the universal theory of refraction and reflection of extraordinary rays (e-rays) in the uniaxial crystal is formulated. Using this theory, a new unit structure prism is designed, and its properties are studied. Based on the theoretical results, such a prism is achieved experimentally by using the Iceland crystal. In both theoretical and experimental studies, this new prism shows excellent polarization splitting performances such as big and adjustable splitting angle, comparing to the conventional Rochon prism. For the sample prism with the optical axis angle of 45°, the splitting angle reaches 19.8°in the normal incidence, and the maximum splitting angle reaches 28.44° while the incidence angle is -4°. PMID:23736569

  14. Out-of-sequence thrusting in experimental Coulomb wedges: Implications for the structural development of mega-splay faults and forearc basins

    NASA Astrophysics Data System (ADS)

    Haq, Saad S. B.

    2012-10-01

    We have investigated how an arc-ward increase in bulk mechanical strength in an experimental accretionary prism influences the development, timing, and duration of slip on out-of-sequence thrusts. We have monitored the structural development and kinematics, in side-view, during the development of a frontally accreting Coulomb wedge growing out in front of a critically tapered and mechanically stronger inner wedge. The inner-wedge initially behaved as classic backstop to deformation with the most actively slipping thrust occurring near the deformation front on the forward most thrust structures. With continued growth, however, significant out-of-sequence slip on reactivated fore-thrusts occurred in conjunction with slip on newly formed back-thrusts in the inner-wedge. This out-of-sequence deformation resulted in punctuated, rapid uplift of the model forearc basin and a noticeable break in topographic slope in the outer pro-wedge. Cyclical out-of-sequence fore- and back-thrusting, driven by ongoing frontal thrust imbrication, continued with periodic recovery of taper and was followed by additional out-of-sequence faulting and associated basin uplift.

  15. Out-Of-Sequence Thrusting In Coulomb Wedges: Implications For The Structural Development Of Mega-Splay Faults And Forearc Basins

    NASA Astrophysics Data System (ADS)

    Haq, S. S.

    2012-12-01

    By quantifying deformation in frictional analog models we have investigated how an arc-ward increase in bulk mechanical strength in an accretionary prism influences the development, timing, and duration of slip on out-of-sequence thrusts. We have monitored the structural development and kinematics, in side-view, during the development of a frontally accreting Coulomb wedge growing out in front of a critically tapered and mechanically stronger inner wedge. The inner-wedge initially behaved as classic backstop to deformation with the most actively slipping thrust occurring near the deformation front on the forward most thrust structures. With continued growth, however, significant out-of-sequence slip on reactivated fore-thrusts occurred in conjunction with slip on newly formed back-thrusts in the inner-wedge. This out-of-sequence deformation resulted in punctuated, rapid uplift of the model forearc basin and a noticeable break in topographic slope in the outer pro-wedge. Cyclical out-of-sequence fore- and back-thrusting, driven by ongoing frontal thrust imbrication, continued with periodic recovery of taper and was followed by additional out-of-sequence faulting and associated basin uplift.

  16. Describing the development of submarine canyons using stream-power erosion laws

    NASA Astrophysics Data System (ADS)

    Mitchell, N. C.

    2004-12-01

    The problem of how turbidity currents erode their beds is important for understanding how canyons develop, but is complex because flow power also varies as a result of incorporation and deposition of the current's suspended load. In some canyons where the total sedimentary mass passing through the canyon has been much larger than the excavated mass, the loads of the eroding currents changed little during passage down-canyon. Canyon morphology can then potentially reveal how gradient and other factors affect erosion rate, illustrated here with two datasets from tectonically active margins. The first dataset is from Tenryu Canyon off Japan, which was entrenched by up to 1200 m by steepening of the Tokai accretionary prism. Incision depth and channel gradient S data [Soh and Tokuyama, 2002] suggest an erosion law in which incision rate E~S0.8, which is remarkably similar to laws for detachment-limited erosion of river beds. In the second dataset, folds of the Barbados prism have created knickpoints [Huyghe et al., 2004]. Numerical modeling reveals that the knickpoints have partly smoothed out, a property of transport-limited erosion, but primarily have translated, a property of detachment-limited erosion. This mixed style of knickpoint development has also been inferred from some bedrock eroding streams on land. If scaling arguments for erosion with flow velocity apply here [Hancock et al., 1998], the inferred dependence of erosion rate on gradient implies that plucking and shear failure rather than abrasion are the main mechanisms in these channels. Hancock, G.S., Anderson, R.S., and Whipple, K.X., 1998, Beyond power: bedrock river incision process and form, in Tinkler, K.J., and Wohl, E.E., eds., Rivers over rock: Fluvial processes in bedrock channels, American Geophysical Union Monogr. 107: p. 35-60. Huyghe, P., M. Foata, E. Deville, and the Caramba Working Group, Channel profiles through the active thrust front of the southern Barbados prism, Geology, 32, 429

  17. Alternating prism exposure causes dual adaptation and generalization to a novel displacement

    NASA Technical Reports Server (NTRS)

    Welch, Robert B.; Bridgeman, Bruce; Anand, Sulekha; Browman, Kaitlin E.

    1993-01-01

    In two experiments, we examined the hypothesis that repeatedly adapting and readapting to two mutually conflicting sensory environments fosters the development of a separate adaptation to each situation (dual adaptation) as well as an increased ability to adapt to a novel displacement (adaptive generalization). In the preliminary study, subjects alternated between adapting their visuomotor coordination to 30-diopter prismatic displacement and readapting to normal vision. Dual adaptation was observed by the end of 10 alternation cycles. However, an unconfounded test of adaptive generalization was prevented by an unexpected prism-adaptive shift in preexposure baselines for the dual-adapted subjects. In the primary experiment, the subjects adapted and readapted to opposite 15-diopter displacements for a total of 12 cycles. Both dual adaptation and adaptive generalization to a 30-diopter displacement were obtained. These findings may be understood in terms of serial reversal learning and 'learning to learn'.

  18. Scaling and efficiency of PRISM in adaptive simulations of turbulent premixed flames

    SciTech Connect

    Tonse, Shaheen R.; Bell, J.B.; Brown, N.J.; Day, M.S.; Frenklach, M.; Grcar, J.F.; Propp, R.M.

    1999-12-01

    The dominant computational cost in modeling turbulent combustion phenomena numerically with high fidelity chemical mechanisms is the time required to solve the ordinary differential equations associated with chemical kinetics. One approach to reducing that computational cost is to develop an inexpensive surrogate model that accurately represents evolution of chemical kinetics. One such approach, PRISM, develops a polynomial representation of the chemistry evolution in a local region of chemical composition space. This representation is then stored for later use. As the computation proceeds, the chemistry evolution for other points within the same region are computed by evaluating these polynomials instead of calling an ordinary differential equation solver. If initial data for advancing the chemistry is encountered that is not in any region for which a polynomial is defined, the methodology dynamically samples that region and constructs a new representation for that region. The utility of this approach is determined by the size of the regions over which the representation provides a good approximation to the kinetics and the number of these regions that are necessary to model the subset of composition space that is active during a simulation. In this paper, we assess the PRISM methodology in the context of a turbulent premixed flame in two dimensions. We consider a range of turbulent intensities ranging from weak turbulence that has little effect on the flame to strong turbulence that tears pockets of burning fluid from the main flame. For each case, we explore a range of sizes for the local regions and determine the scaling behavior as a function of region size and turbulent intensity.

  19. Mud volcano venting induced gas hydrate formation at the upper slope accretionary wedge, offshore SW Taiwan

    NASA Astrophysics Data System (ADS)

    Lin, Saulwood; Tseng, Yi-Ting; Cheng, Wan-Yen; Chou, Cheng-Tien; Chen, NeiChen; Hsieh, I.-Chih

    2016-04-01

    TsanYao Mud Volcano (TYMV) is the largest mud volcano cone in the Hengchun Mud Volcano Group (HCMVG), located at the upper slope of the accrretionary wedge, southwest of Taiwan. The region is under active tectonic activity with the Philippine Plate, moving northwestward at a rate of ~8 cm/year. This region also receives huge quantity of suspended particle load of ~100 mT/year at present time from adjacent small rivers of the Island of Taiwan. Large loads of suspended sediments influx become a major source of organic carbon and later gas and other hydrocarbon. Gas and fluid in the mud volcano are actively venting from deep to the sea floor on the upper slope of the accretionary wedge. In order to understand venting on the HCMVG, echo sounder, towcam and coring were carried out. Pore water sulfate, chloride, potassium, calcium, stable isotope O-18, gas compositions, dissolved sulfide were analysed. The HCMVG consists of 12 volcano cones of different sizes. Large quantity of gas and fluid are venting directly from deep to the TYMV structure high, as well as 50+ other vents as appeared as flares on the echo sounder. Some flares are reaching to the atmosphere and likely a source of green house gases to the atmosphere. Venting fluids include gas bubbles, suspended particle, mud, and breccia. Breccia size could reach more than 12 cm in diameter. Circular bands in different color appeared around the cone may represent stages of vent eruptions. Compositions of vent gas include methane, ethane and propane. High proportions of ethane and propane in the vent gas demonstrated that source of gas are thermogenic in origin. Patchy authigenic carbonate, bacterial mats, bivalves, tube worms and other chemosynthesis organisms were supported by venting gas AOM process near the sea floor. Pore water chloride concentrations show distinct variation pattern from center cone to the side of the volcano, with low in the center and high away from the cone. Pore water with higher than seawater

  20. The Calm Before the Storm: Exploring the Post Accretionary Doldrums Prior to the Late Heavy Bombardment

    NASA Astrophysics Data System (ADS)

    Bottke, W. F., Jr.

    2015-12-01

    The early bombardment of the inner solar system played a critical role in planetary evolution, but there is still considerable uncertainty about what happened when. Dynamical models suggest two major bombardment phases may have taken place: (i) a post-accretionary period where newly-formed worlds were struck by leftover planetesimals, and (ii) a late heavy bombardment period, possibly produced by conditions related to a violent reshuffling of the planets ~4.1-4.2 Gyr ago (Ga). If valid, a relative impact lull took place between the two bombardment phases. We explore the evidence for such doldrums in this talk. Consider: a) Mars. Geochemical and meteorite evidence indicates the giant 10,600 × 8,500 km Borealis basin formed > 4.5 Ga. Many postulated basins forming afterwards, however, can be ruled out by the surprisingly pristine nature of the Borealis boundary in topography and gravity. Three of the four largest remaining basins, Hellas, Isidis, and Argyre, have superposed craters counts indicating they are < 4.1 Ga. b) Asteroids. The oldest and most extensive sets of 39Ar-40Ar shock degassing ages, found within meteorites that were heavily shocked, shock-melted, or otherwise showed some evidence for having been part of a large collision, show age clusters between ~3.5-4.1 Ga and ~4.4-4.54 Ga. Using dynamical/impact heating models, it can be argued that relatively few projectiles were on planet-crossing orbits between ~4.1-4.4 Ga. c) Moon. The Moon is probably 4.47 Ga, yet most sample evidence for basin-sized impacts may be < 4.2 Ga. The age gap is curious unless many basins were created close in time to the solidification of the lunar crust. Using collisional/dynamical models, it can be shown that many early basins and craters formed > 4.4 Ga. Here the early impactors may be surviving debris from the Moon-forming giant impact event; note that ejecta initially escaping the Earth-Moon system can come back over many tens of Myr. This would leave doldrums between ~4

  1. Identification and Analysis of Methane Plumes from the Barbados Accretionary Complex Identified in Multibeam Sonar Data

    NASA Astrophysics Data System (ADS)

    Barnard, A.; Casey, J.

    2013-12-01

    Integration of modern high-resolution multibeam deliverables can relate water column features to seafloor geologic structures. As well as providing coverage of wide areas, the data can also be used to infer volume and variability of gas seeps and characterize the spatial relationships with seafloor features. As part of cruise AT21-02 to the Barbados Accretionary Complex a ~12 kHz Kongsberg EM122 hull-mounted multibeam system was deployed. We processed the multibeam data using the QPS modules to produce a subsea 4D multi-resolution scene files containing bathymetry, acoustic backscatter and midwater data. Within the scene we have identified a region of giant mud volcanoes and a second region along strike containing several ~1000 m tall flares in the water column data directly above cratered hummocky seafloor with high amplitude backscatter at ~-1500 m water depth that are interpreted as ebullition craters beneath gas plumes. From the acoustic returns we relate the bubble diameter or volume to the received signal strength. Evidence exists for armoring of the gas bubbles in the water column by hydrate: the modeled gas hydrate stability zone reaches ~600 m above the seafloor but the acoustic resolution of our dataset is similar to the maximum depth of disappearance of the bubble plume. The shear observed in the rising gas plume may be the result of transport in the current direction of the lowest water mass from the northwest to southeast at 128°, a direction similar to the transport direction of the lowest water mass in this region, or the presence of abyssal undular vortices. Seismic data from this area has bottom simulating reflectors indicating the presence of methane hydrate and it is likely that the observed flares are related to dissociation of methane in the subsurface. The release of gasses may be related to changes in the thickness of the gas hydrate stability zone in the underlying sediments responding to temperature changes in the lowest water mass. To

  2. Minimum work analysis on the critical taper accretionary wedges- insights from analogue modeling

    NASA Astrophysics Data System (ADS)

    Santimano, Tasca; Rosenau, Matthias; Oncken, Onno

    2014-05-01

    The Critical taper theory (CTT) is a fundamental concept for the understanding of mountain building processes. Based on force balance it predicts the preferred steady state geometry of an accretionary wedge system and its tectonic regime (extensive, compressive, stable). However, it does not specify which structures are formed and reactivated to reach the preferred state. The latter can be predicted by the minimum work concept. Here we test both concepts and their interplay by analysing two simple sand wedge models which differ only in the thickness of the basal detachment (a layer of glass beads). While the steady state critical taper is controlled by internal and basal friction coefficients and therefore the same in all experiments, different processes can minimise work by 1. reducing gravitational work e.g. by lowering the amount of uplift or volume uplifted, or 2. reducing frictional work e.g. by lowering the load or due to low friction coefficient along thrusts. Since a thick detachment allows entrainment of low friction material and therefore lowering of the friction along active thrusts, we speculate that the style of wedge growth will differ between the two models. We observe that the wedge with a thin basal detachment localizes strain at the toe of the wedge periodically and reactivate older faults to reach the critical topography. On the contrary, in the wedge with the thicker detachment layer, friction along thrusts is lowered due to the entrainment of low friction material from the detachment zone, subsequently increasing the lifetime of a thrust. Long thrust episodes are always followed by a fault of shorter lifetime, with the aim of reaching the critical taper. From the two experiments, we analyze the time-series evolution of the wedge to infer the work done by the two styles of deformation and predict the trend over time to differ but the maximum work to be similar Our observations show that the critical taper theory determines the geometry of the

  3. MATLAB code for estimating magnetic basement depth using prisms

    NASA Astrophysics Data System (ADS)

    Aydın, Ibrahim; Oksum, Erdinc

    2012-09-01

    There is a need, within both geophysical exploration and deep geophysical research, to estimate magnetic basement depth. Forward and inverse modeling studies to map the basement depth are commonly used within petroleum geophysics. To obtain the basement topography, modeling studies are made of the 2D profile data or 3D map data. In this study, a different algorithm was introduced to estimate the magnetic basement depth from map data. The algorithm is based on the analytical solution of exponential equations obtained from Fourier transformation of magnetic data. This algorithm has been tested on synthetic magnetic anomalies originated from multi-prisms. Following encouraging test results, the proposed algorithm was also tested on field data. The depths obtained from the proposed approach were satisfactory in comparison with the depths obtained from seismic survey cross-sections and boreholes. Basic MATLAB code is included in the Appendix.

  4. Dove prism based rotating dual beam bidirectional Doppler OCT.

    PubMed

    Blatter, Cedric; Coquoz, Séverine; Grajciar, Branislav; Singh, Amardeep S G; Bonesi, Marco; Werkmeister, René M; Schmetterer, Leopold; Leitgeb, Rainer A

    2013-07-01

    Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its accuracy in clinical practice. To overcome this limitation, we use a bidirectional dual beam technique equipped with a novel rotating scanning scheme employing a Dove prism. The volume is probed from two distinct illumination directions with variable controlled incidence plane, allowing for reconstruction of the true flow velocity at arbitrary vessel orientations. The principle is implemented with Swept Source OCT at 1060nm with 100,000 A-Scans/s. We apply the system to resolve pulsatile retinal absolute blood velocity by performing segment scans around the optic nerve head and circumpapillary scan time series. PMID:23847742

  5. Dove prism based rotating dual beam bidirectional Doppler OCT

    PubMed Central

    Blatter, Cedric; Coquoz, Séverine; Grajciar, Branislav; Singh, Amardeep S. G.; Bonesi, Marco; Werkmeister, René M.; Schmetterer, Leopold; Leitgeb, Rainer A.

    2013-01-01

    Traditional Doppler OCT is highly sensitive to motion artifacts due to the dependence on the Doppler angle. This limits its accuracy in clinical practice. To overcome this limitation, we use a bidirectional dual beam technique equipped with a novel rotating scanning scheme employing a Dove prism. The volume is probed from two distinct illumination directions with variable controlled incidence plane, allowing for reconstruction of the true flow velocity at arbitrary vessel orientations. The principle is implemented with Swept Source OCT at 1060nm with 100,000 A-Scans/s. We apply the system to resolve pulsatile retinal absolute blood velocity by performing segment scans around the optic nerve head and circumpapillary scan time series. PMID:23847742

  6. Hybrid-integrated prism array optoelectronic targeting system

    NASA Astrophysics Data System (ADS)

    Chang, C. C.; Chang, H. C.; Tang, L. C.; Young, W. K.; Wang, J. C.; Huang, K. L.

    2005-11-01

    This investigation proposes a cost-effective, compact, and robust optoelectronic targeting system for measuring ballistic impact velocity and the distribution of projectile motion. The major elements of this system are four photo-gates hybridized by compound one-dimensional prism array and analog/digital electronic components. The number of light sources and photodetectors used in a photo-gate was reduced to one pair of light source and photodetector. The average velocity and location of the projectile are determined according to the measured time intervals ( ˜10 -8 s) passing each pair. The system can accurately measure the velocity of a bullet as it leaves a gun barrel, as well as the velocity at specific points along the trajectory outside the firearm. Additionally, the system uses a widespread low-powered laser pointer as a light source. Compared with other optoelectronic targeting systems that use high-powered lasers, the proposed system is both economical and safe.

  7. Optical device with conical input and output prism faces

    DOEpatents

    Brunsden, Barry S.

    1981-01-01

    A device for radially translating radiation in which a right circular cylinder is provided at each end thereof with conical prism faces. The faces are oppositely extending and the device may be severed in the middle and separated to allow access to the central part of the beam. Radiation entering the input end of the device is radially translated such that radiation entering the input end at the perimeter is concentrated toward the output central axis and radiation at the input central axis is dispersed toward the output perimeter. Devices are disclosed for compressing beam energy to enhance drilling techniques, for beam manipulation of optical spatial frequencies in the Fourier plane and for simplification of dark field and color contrast microscopy. Both refracting and reflecting devices are disclosed.

  8. Larmor labeling of neutron spin using superconducting Wollaston prisms

    NASA Astrophysics Data System (ADS)

    Li, Fankang

    Neutron spin Larmor labeling using magnetic Wollaston prisms (WP) provides a way to overcome some of the limitations arising from the nature of neutron beams: low flux and divergence. Using superconducting films and tapes, a series of strong, well-defined shaped magnetic fields can be produced due to both the zero-resistance and Meissner effect in superconductors. Using finite element simulations, the criterion to build a superconducting magnetic Wollaston prism with high encoding efficiency and low Larmor phase aberrations are presented. To achieve a high magnetic field and simplify the maintenance, we optimize the design using careful thermal analysis. The measured neutron spin flipping efficiency is measured to be independent of both the neutron wavelength and energizing current, which is a significant improvement over other devices with similar functions. A highly linear variation of the Larmor phase is measured across the device, which ensures a highly uniform encoding of scattering angles into the neutron spin Larmor phase. Using two WPs, the correlation function for a colloidal silica sample was measured by spin echo modulated small angle neutron scattering (SEMSANS) and agrees well with other techniques. Using Monte Carlo code (McStas), we further investigated the SEMSANS setup and showed the requirements to improve its performance. We have proposed a new technique to implement neutron spin echo on a triple axis neutron spectrometer to achieve high resolution measurements of the lifetime of dispersive phonon excitations. The spin echo is tuned by appropriate choice of magnetic fields instead of physically tilting the coils used in traditional methods. This new approach allows a higher energy resolution and a larger effective tilting angle and hence larger group velocity to be measured.

  9. The penta-prism LTP: A long-trace-profiler with stationary optical head and moving penta prism

    SciTech Connect

    Qian, S.; Jark, W. ); Takacs, P.Z. )

    1995-03-01

    Metrology requirements for optical components for third-generation synchrotron sources are taxing the state of the art in manufacturing technology. We have investigated a number of error sources in a commercial figure measurement instrument, the Long-Trace-Profiler II, and have demonstrated that, with some simple modifications, we can significantly reduce the effect of error sources and improve the accuracy and reliability of the measurement. By keeping the optical head stationary and moving a penta prism along the translation stage, as in the original pencil-beam interferometer design of von Bieren, the stability of the optical system is greatly improved, and the remaining error signals can be corrected by a simple reference beam subtraction. We illustrate the performance of the modified system by investigating the distortion produced by gravity on a typical synchrotron mirror and demonstrate the repeatability of the instrument despite relaxed tolerances on the translation stage.

  10. The penta-prism LTP: A long-trace-profiler with stationary optical head and moving penta prism (abstract)

    SciTech Connect

    Qian, S.; Jark, W. ); Takacs, P.Z. )

    1995-02-01

    Metrology requirements for optical components for third generation synchrotron sources are taxing the state-of-the-art in manufacturing technology. We have investigated a number of effect sources in a commercial figure measurement instrument, the Long Trace Profiler II (LTP II), and have demonstrated that, with some simple modifications, we can significantly reduce the effect of error sources and improve the accuracy and reliability of the measurement. By keeping the optical head stationary and moving a penta prism along the translation stage, the stability of the optical system is greatly improved, and the remaining error signals can be corrected by a simple reference beam subtraction. We illustrate the performance of the modified system by investigating the distortion produced by gravity on a typical synchrotron mirror and demonstrate the repeatability of the instrument despite relaxed tolerances on the translation stage.

  11. Is the Aligning Prism Measured with the Mallett Unit Correlated with Fusional Vergence Reserves?

    PubMed Central

    Conway, Miriam L.; Thomas, Jennifer; Subramanian, Ahalya

    2012-01-01

    Background The Mallett Unit is a clinical test designed to detect the fixation disparity that is most likely to occur in the presence of a decompensated heterophoria. It measures the associated phoria, which is the “aligning prism” needed to nullify the subjective disparity. The technique has gained widespread acceptance within professions such as optometry, for investigating suspected cases of decompensating heterophoria; it is, however, rarely used by orthoptists and ophthalmologists. The aim of this study was to investigate whether fusional vergence reserves, measured routinely by both orthoptists and ophthalmologists to detect heterophoria decompensation, were correlated with aligning prism (associated phoria) in a normal clinical population. Methodology/Principal Findings Aligning prism (using the Mallett Unit) and fusional vergence reserves (using a prism bar) were measured in 500 participants (mean 41.63 years; standard deviation 11.86 years) at 40 cm and 6 m. At 40 cm a strong correlation (p<0.001) between base in aligning prism (Exo FD) and positive fusional reserves was found. Of the participants with zero aligning prism 30% had reduced fusional reserves. At 6 m a weak correlation between base out aligning prism (Eso FD) and negative fusional reserves was found to break (p = 0.01) and to recovery (p = 0.048). Of the participants with zero aligning prism 12% reported reduced fusional reserves. Conclusions/Significance For near vision testing, the strong inverse correlation between base in aligning prism (Exo FD) and fusional vergence reserves supports the notion that both measures are indicators of decompensation of heterophoria. For distance vision testing and for those patients reporting zero aligning prism further research is required to determine why the relationship appears to be weak/non-existent? PMID:22905174

  12. A bi-prism interferometer for hard x-ray photons

    SciTech Connect

    Isakovic, A.F.; Siddons, D.; Stein, A.; Warren, J.B.; Sandy, A.R.; Narayanan, M.S.; Ablett, J.M.; Metzler, M. and Evans-Lutterodt, K.

    2010-04-06

    Micro-fabricated bi-prisms have been used to create an interference pattern from an incident hard X-ray beam, and the intensity of the pattern probed with fluorescence from a 30 nm-thick metal film. Maximum fringe visibility exceeded 0.9 owing to the nano-sized probe and the choice of single-crystal prism material. A full near-field analysis is necessary to describe the fringe field intensities, and the transverse coherence lengths were extracted at APS beamline 8-ID-I. It is also shown that the maximum number of fringes is dependent only on the complex refractive index of the prism material.

  13. CLESSIDRA: Focusing Hard X-Rays Efficiently with Arrays Composed of Small Prisms

    SciTech Connect

    Jark, Werner; Perennes, Frederic; Matteucci, Marco; Mancini, Lucia; Menk, Ralf H.; Rigon, Luigi

    2007-01-19

    Small prisms arranged such that the number of prisms to traverse by an x-ray beam is linearly increasing with distance from the symmetry axis of the device will direct an incident wave to a common cross over point. This structure can be understood as a special form of the Fresnel version of a concave refractive x-ray lens. Indeed it is obtained by removing blocks of optically passive material of equal height from the concave lens shape. It will be shown that the structure has a high refraction efficiency and that the losses are produced by problems in the fabrication of sufficiently sharp tips for the prisms.

  14. Properties of YMnO{sub 3} self-assembled nanocrystalline prisms on GaN

    SciTech Connect

    Keenan, Cameron; Chandril, Sandeep; Myers, Thomas H.; Lederman, David; Ramos-Moore, E.; Cabrera, A. L.

    2008-01-07

    Growth of YMnO{sub 3} on GaN (0001) using molecular beam epitaxy at temperatures greater than 850 deg. C resulted in the spontaneous formation of crystalline prisms, ranging from 20 to 60 nm in height and 50 to 500 nm in lateral size, surrounded by a 6 nm thick continuous YMnO{sub 3} film. The local dielectric properties were measured using scanning surface probe microscopy. The prisms were ferroelectric at room temperature and their ferroelectric properties were enhanced for taller prisms. This is consistent with these structures being less constrained than the continuous layer, which is clamped by the surrounding unpolarized film.

  15. Third-order theory of the Risley-prism-based beam steering system.

    PubMed

    Li, Yajun

    2011-02-10

    Nonparaxial ray tracing is performed to investigate the field scanned out by a single beam through two rotatable thick prisms with different parameters, and a general solution is obtained and then expanded into a power series to establish the third-order theory for Risley prisms that paves the way to investigate topics of interest such as optical distortions in the scan pattern and an analytical solution of the inverse problem of a Risley-prism-based laser beam steering system; i.e., the problem is concerned with how to direct a laser beam to any specified direction within the angular range of the system. PMID:21343989

  16. Enhanced performance of wind energy harvester by aerodynamic treatment of a square prism

    NASA Astrophysics Data System (ADS)

    Hu, Gang; Tse, K. T.; Kwok, K. C. S.

    2016-03-01

    This letter presents the effects that fitting fins to various corners of a square-prism galloping-based piezoelectric energy harvester (PEH) has on its performance, based on results from a series of wind tunnel model tests. The results show that attaching fins to the leading edge significantly improves the efficiency of the harvester, achieving a maximum power 2.5 times that attained by a plain square prism PEH. Furthermore, a length that is 1/6 of the prism's cross-sectional width is found to be optimal for fins that are attached to the harvester.

  17. The effect of a compliant accretionary wedge on earthquake rupture and tsunamigenesis

    NASA Astrophysics Data System (ADS)

    Lotto, Gabriel; Jeppson, Tamara; Dunham, Eric; Tobin, Harold

    2016-04-01

    The 11 March 2011 Tohoku megathrust earthquake ruptured through the shallowest part of the subduction zone boundary, resulting in tens of meters of displacement at the seafloor. This extreme shallow slip generated a devastating tsunami. The elastic properties of off-fault materials have an important role in determining slip along a fault. Laboratory ultrasonic velocity measurements performed on samples of rock obtained from the area surrounding the Tohoku earthquake principal fault zone during the Japan Trench Fast Drilling Project (JFAST) have shown that shallow off-fault materials are extremely compliant - P-wave velocities of 2.0-2.4 km/s, S-wave velocities of 0.7-1.0 km/s, and shear moduli ranging from 1.0-2.2 GPa. Seismic imaging around the JFAST drill site corroborates the presence of a compliant, low-velocity frontal prism at the toe of the hanging wall. This compliant wedge is likely a fairly robust feature across the horizontal extent of the Japan Trench and may have contributed to the large amount of displacement recorded. In order to investigate the impact of compliant off fault materials on earthquake rupture and tsunamigenesis, we employ a 2-D finite difference method that models the full seismic and tsunami wavefield associated with dynamic rupture on a dipping fault in a heterogeneous medium. Our numerical method rigorously couples the elastodynamic response of the solid Earth to that of a compressible ocean in the presence of gravity. Idealized models of subduction zone earthquakes show that the presence of a compliant wedge leads to increased slip, greater seafloor displacement, and a larger tsunami. However, preliminary results for a representative Tohoku geometry were not so simple; the compliant wedge enhanced slip and seafloor deformation but only in a localized zone, and tsunami height was not significantly affected. This surprising result indicates that the details of geometry and material structure we observe in real subduction zones are

  18. Measurement of two-dimensional small angle deviation with a prism interferometer

    SciTech Connect

    Chatterjee, Sanjib; Kumar, Y. Pavan

    2008-09-20

    A new technique for the measurement of two-dimensional small angular deviation is presented. A compound prism, which effectively produces a combination of two right-angled prisms in orthogonal directions, and plane reference surfaces have been utilized for the measurement of the orthogonal components of the angular tilt of an incident plane wavefront. Each orthogonal component of the angular tilt is separately measured from the angular rotation of the resultant wedge fringes between two plane wavefronts generated due to splitting of the incident plane wavefront by the corresponding set of right-angled prism and plane reference surface. The technique is shown to have high sensitivity for the measurement of small angle deviation. A monolithic prism interferometer, which is practically insensitive to vibration, is also proposed. Results obtained for the measurement of a known tilt angle are presented.

  19. C&O Canal prism, with towpath (left) and fill under WM ...

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

    C&O Canal prism, with towpath (left) and fill under WM roadbed (right), milepost 142 vicinity, looking southwest. - Western Maryland Railway, Cumberland Extension, Pearre to North Branch, from WM milepost 125 to 160, Pearre, Washington County, MD

  20. Theoretical and experimental determination of steering mechanism for Risley prism systems.

    PubMed

    Lu, Yafei; Zhou, Yuan; Hei, Mo; Fan, Dapeng

    2013-03-01

    Two different analytical methods, the first-order paraxial approximation method and the nonparaxial ray tracing method, are applied to determine the steering mechanism of the Risley prism system, including the pointing prediction and the complete and exact inverse orientation solutions. The analytical results obtained with the two different methods are investigated in detail about the pointing prediction and the two groups of inverse orientation solutions, respectively. Risley prism equipment for wide angular range beam scanning is assembled and the experimental setup is built to test the steering mechanism of the Risley prism system. Experimental results validate the availability of the nonparaxial ray tracing method to discuss the beam steering mechanism for the Risley prism system. PMID:23458790

  1. Modelling and design of modified Wollaston prisms and the application in differential interference contrast microscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Site; Zhong, Huiying; Wyrowski, Frank

    2016-03-01

    Wollaston prisms and the modified Wollaston prisms, which are interesting for various applications like optical metrology, topography of surfaces and biological imaging, has been theoretically studied and also been practically applied. The previous studies are mostly based on ray tracing analysis and, as a result, the information that can be obtained are somehow restricted. In this paper, we propose a geometric field tracing technique for the simulation of light propagation through Wollaston prisms. In geometric field tracing we seek for the solutions to Maxwell's equations under the geometrical optics approximation, so that all the properties of light as electromagnetic field are retained. Using the proposed simulation technique, we present the simulation of a differential interference contrast (DIC) microscopy, in which the modified Wollaston prism is used as the key component.

  2. Effect of prism index on sensitivity of lossy mode resonance sensors operating in visible region

    NASA Astrophysics Data System (ADS)

    Kaur, Davinder; Sharma, Vinod K.; Kapoor, Avinashi

    2015-01-01

    We present the theoretical results of the optimization of lossy mode resonance sensors at visible wavelengths. Both angular and spectral interrogations are carried out for absorbing indium tin oxide (ITO) films placed on glass prism. The inclusion of a low-index layer between the prism and the lossy (ITO) layer can produce an efficient refractive index sensor for bio/chemical applications. Further increase in sensitivity can be achieved by changing the index of the prism. It is shown that the sensitivity has strong dependence on the index of prism. Sensitivities as high as 4670 nm/RIU for spectral mode and 67 deg/RIU for angular mode with small values of full width at half maximum (FWHM) can be achieved. Dependence of sensitivity and FWHM on refractive index and thickness of low-index matching layer is also investigated.

  3. The initial point of collimator CCD imagine calibration by pyramid prism

    NASA Astrophysics Data System (ADS)

    Wang, Zongping; Jin, Shangzhong; Wang, Weicheng; Zhu, Xiaoping

    2013-12-01

    This paper briefly introduces the commonly used photoelectric auto collimator structure and its working principle. A new method for calibrating the initial point of collimator CCD imagine by a pyramid prism was proposed. It consists of a two-dimension rotate instrument, a pyramid prism and a collimator. By combing with the algorithm of calculating the center position of beam spot, a more precise calibration of the initial point of the collimator CCD imagine was realized. Optical properties of the pyramid prism and its impact of initial point calibration were analysed under the oblique incidence. At the same time, effect of the manufacturing errors of pyramid prism on the calibration accuracy was analysed. Experimental data shows that the method has a good reproducibility with a relative standard deviation of less than 10%.

  4. Prism-C2n carbon dimer, trimer, and nano-sheets: A quantum chemical study

    NASA Astrophysics Data System (ADS)

    Ohno, Koichi; Satoh, Hiroko; Iwamoto, Takeaki

    2015-07-01

    Quantum chemical calculations have predicted the existence of a new carbon family with double-layered structures formed by arranging prism-C2n (n = 6, 8, and 12) units. Theoretical explorations of potential energy surfaces suggest the lowest barriers of the reaction channels to be ca. 30 kJ mol-1 for a D2h prism-C16 dimer and a D3h prism-C24 trimer. Geometry optimizations under periodic boundary conditions yield some prism-C2n sheets composed of CC single bonds of ca. 0.15-0.16 nm. The relative energies per one atom with respect to graphene are 90-160 kJ mol-1. Van der Waals thickness is estimated to be ca. 0.5 nm.

  5. Advancing the Parameter-elevation Regressions on Independent Slopes Model (PRISM) to Accommodate Atmospheric River Influences Using a Hierarchical Estimation Structure

    NASA Astrophysics Data System (ADS)

    Hsu, C.; Cifelli, R.; Zamora, R. J.; Schneider, T.

    2014-12-01

    The PRISM monthly climatology has been widely used by various agencies for diverse purposes. In the River Forecast Centers (RFCs), the PRISM monthly climatology is used to support tasks such as QPE, or quality control of point precipitation observation, and fine tune QPFs. Validation studies by forecasters and researchers have shown that interpolation involving PRISM climatology can effectually reduce the estimation bias for the locations where moderate or little orographic phenomena occur. However, many studies have pointed out limitations in PRISM monthly climatology. These limitations are especially apparent in storm events with fast-moving wet air masses or with storm tracks that are different from climatology. In order to upgrade PRISM climatology so it possesses the capability to characterize the climatology of storm events, it is critical to integrate large-scale atmospheric conditions with the original PRISM predictor variables and to simulate them at a temporal resolution higher than monthly. To this end, a simple, flexible, and powerful framework for precipitation estimation modeling that can be applied to very large data sets is thus developed. In this project, a decision tree based estimation structure was developed to perform the aforementioned variable integration work. Three Atmospheric River events (ARs) were selected to explore the hierarchical relationships among these variables and how these relationships shape the event-based precipitation distribution pattern across California. Several atmospheric variables, including vertically Integrated Vapor Transport (IVT), temperature, zonal wind (u), meridional wind (v), and omega (ω), were added to enhance the sophistication of the tree-based structure in estimating precipitation. To develop a direction-based climatology, the directions the ARs moving over the Pacific Ocean were also calculated and parameterized within the tree estimation structure. The results show that the involvement of the

  6. PrismTech Data Distribution Service Java API Evaluation

    NASA Technical Reports Server (NTRS)

    Riggs, Cortney

    2008-01-01

    My internship duties with Launch Control Systems required me to start performance testing of an Object Management Group's (OMG) Data Distribution Service (DDS) specification implementation by PrismTech Limited through the Java programming language application programming interface (API). DDS is a networking middleware for Real-Time Data Distribution. The performance testing involves latency, redundant publishers, extended duration, redundant failover, and read performance. Time constraints allowed only for a data throughput test. I have designed the testing applications to perform all performance tests when time is allowed. Performance evaluation data such as megabits per second and central processing unit (CPU) time consumption were not easily attainable through the Java programming language; they required new methods and classes created in the test applications. Evaluation of this product showed the rate that data can be sent across the network. Performance rates are better on Linux platforms than AIX and Sun platforms. Compared to previous C++ programming language API, the performance evaluation also shows the language differences for the implementation. The Java API of the DDS has a lower throughput performance than the C++ API.

  7. Surface plasmon resonance prism coupler for enhanced circular dichroism sensing.

    PubMed

    Phan, Quoc-Hung; Lo, Yu-Lung; Huang, Chih-Ling

    2016-06-13

    A novel method for enhanced circular dichroism (CD) detection is proposed based on a surface plasmon resonance (SPR) prism coupler and a polarization scanning ellipsometry technique. An analytical model is derived to extract the CD and degree of polarization (DOP) properties of optical samples with and without scattering effects, respectively. The validity of the analytical model is confirmed by means of numerical simulations. The simulation results show that the proposed detection method has a sensitivity of 10-5~10-6 RIU (refractive index unit) for refractive indices in the range of 1.32~1.36 and 1.3100~1.3118. The practical feasibility of the proposed method is demonstrated by the experimental results for the sensitivity of the CD with the chlorophyllin samples with/without scattering effect. It is shown that for both types of sample, the extracted CD value increases linearly with the chlorophyll concentration over the considered range. In general, the results obtained in this study show that the measured CD response is highly sensitive to the polarization scanning angle. Consequently, the potential of polarization scanning ellipsometry for high-resolution CD detection is confirmed. PMID:27410300

  8. Hypnotizability and Performance on a Prism Adaptation Test.

    PubMed

    Menzocchi, Manuel; Mecacci, Giulio; Zeppi, Andrea; Carli, Giancarlo; Santarcangelo, Enrica L

    2015-12-01

    The susceptibility to hypnosis, which can be measured by scales, is not merely a cognitive trait. In fact, it is associated with a number of physiological correlates in the ordinary state of consciousness and in the absence of suggestions. The hypnotizability-related differences observed in sensorimotor integration suggested a major role of the cerebellum in the peculiar performance of healthy subjects with high scores of hypnotic susceptibility (highs). In order to provide behavioral evidence of this hypothesis, we submitted 20 highs and 21 low hypnotizable participants (lows) to the classical cerebellar Prism Adaptation Test (PAT). We found that the highs' performance was significantly less accurate and more variable than the lows' one, even though the two groups shared the same characteristics of adaptation to prismatic lenses. Although further studies are required to interpret these findings, they could account for earlier reports of hypnotizability-related differences in postural control and blink rate, as they indicate that hypnotizability influences the cerebellar control of sensorimotor integration. PMID:25913127

  9. PrISM: Mapping Nearby Galaxies with Slit Spectroscopy

    NASA Astrophysics Data System (ADS)

    Sterling Rich, Jeffrey Austin

    2015-08-01

    The information gained from spatially resolved optical spectroscopy has proven crucial to understanding the complete picture of galaxies and their contents. In order to fully understand the interplay between the processes that govern and regulate star formation and galaxy evolution we are building building a sample of the largest, highest spatial resolution, and widest spectral coverage data cubes ever taken for nearby galaxies: the Las Campanas PrISM Survey.I will present recent results and ongoing work using our data cubes to map the ionized ISM and its properties at spatial scales of order 10 pc in nearby galaxies such as M83. The high spatial resolution of our data affords us the opportunity to study the characteristics and total contribution of diffuse ionized gas, a less well-understood component of nearby galaxies, as well as metallicties, star formation rates gas kinematics and more. I will also discuss how resolved spectroscopy can help detect, quantify and distinguish between star formation, shocks, diffuse ionized gas and AGN to help better inform larger, less resolved studies of galaxy properties.

  10. Highly Sideophile Element Abundance Constraints on the Nature of the Late Accretionary Histories of Earth, Moon and Mars

    NASA Technical Reports Server (NTRS)

    Walker, R. J.; Puchtel, I. S.; Brandon, A. D.; Horan, M. F.; James, O. B.

    2007-01-01

    The highly siderophile elements (HSE) include Re, Os, Ir, Ru, Pt and Pd. These elements are initially nearly-quantitatively stripped from planetary silicate mantles during core segregation. They then may be re-enriched in mantles via continued accretion sans continued core segregation. This suite of elements and its included long-lived radiogenic isotopes systems (Re-187 (right arrow) Os-187; Pt-190 (right arrow) Os-186) can potentially be used to fingerprint the characteristics of late accreted materials. The fingerprints may ultimately be useful to constrain the prior nebular history of the dominant late accreted materials, and to compare the proportion and genesis of late accretionary materials added to the inner planets. The past ten years have seen considerable accumulation of isotopic and compositional data for HSE present in the Earth's mantle, lunar mantle and impact melt breccias, and Martian meteorites. Here we review some of these data and consider the broader implications of the compiled data.

  11. Preliminary evaluation of the petroleum potential of the Tertiary accretionary terrane, west side of the Olympic Peninsula, Washington

    SciTech Connect

    Not Available

    1989-01-01

    Convergence between the Pacific and North American plates during late Eocene and late middle Miocene times produced two principal terranes of melange and broken formation (Eocene, Ozette Melange and Miocene, Hoh Melange) exposed onshore along the west side of the Olympic Peninsula. Organic geochemical analyses of 150 samples collected from these two accretionary terranes indicate that they are marginally mature and have a low content of type III organic matter, therefore, they are gas prone rather than oil prone. Geochemical analyses, using molecular markers, indicate that the oil in the Sunshine Mining Co. Medina No. 1 is related to oil extracted from middle Eocene siltstone of the Ozette Melange located as much as 140 km north of the well. The stable carbon and hydrogen isotopic abundance of methane in natural gas seeps and gas in the melange along the west side of the Olympic Peninsula indicate that the gas is mainly thermogenic; however, the relation between these two sources of gas is uncertain.

  12. Rhomboid prism pair for rotating the plane of parallel light beams

    NASA Technical Reports Server (NTRS)

    Orloff, K. L. (Inventor); Yanagita, H.

    1982-01-01

    An optical system is described for rotating the plane defined by a pair of parallel light beams. In one embodiment a single pair of rhomboid prisms have their respective input faces disposed to receive the respective input beams. Each prism is rotated about an axis of revolution coaxial with each of the respective input beams by means of a suitable motor and gear arrangement to cause the plane of the parallel output beams to be rotated relative to the plane of the input beams. In a second embodiment, two pairs of rhomboid prisms are provided. In a first angular orientation of the output beams, the prisms merely decrease the lateral displacement of the output beams in order to keep in the same plane as the input beams. In a second angular orientation of the prisms, the input faces of the second pair of prisms are brought into coincidence with the input beams for rotating the plane of the output beams by a substantial angle such as 90 deg.

  13. Prism adaptation reverses the local processing bias in patients with right temporo-parietal junction lesions

    PubMed Central

    Rafal, Robert D.; List, Alexandra

    2009-01-01

    Lesions to the right temporo-parietal cortex commonly result in hemispatial neglect. Lesions to the same area are also associated with hyperattention to local details of a scene and difficulty perceiving the global structure. This local processing bias is an important factor contributing to neglect and may contribute to the higher prevalence of the disorder following right compared with left hemisphere strokes. In recent years, visuomotor adaptation to rightward-shifting prisms has been introduced as a promising treatment for hemispatial neglect. Explanations for these improvements have generally described a leftward realignment of attention, however, the present investigation provides evidence that prism adaptation reduces the local processing bias. Five patients with right temporal-parietal junction lesions were asked to identify the global or local levels of hierarchical figures before and after visuomotor adaptation to rightward-shifting prisms. Prior to prism adaptation the patients had difficulty ignoring the local elements when identifying the global component. Following prism adaptation, however, this pattern was reversed, with greater global interference during local level identification. The results suggest that prism adaptation may improve non-spatially lateralized deficits that contribute to the neglect syndrome. PMID:19416951

  14. Modelling the differential effects of prisms on perception and action in neglect.

    PubMed

    Leigh, Steven; Danckert, James; Eliasmith, Chris

    2015-03-01

    Damage to the right parietal cortex often leads to a syndrome known as unilateral neglect in which the patient fails to attend or respond to stimuli in left space. Recent work attempting to rehabilitate the disorder has made use of rightward-shifting prisms that displace visual input further rightward. After a brief period of adaptation to prisms, many of the symptoms of neglect show improvements that can last for hours or longer, depending on the adaptation procedure. Recent work has shown, however, that differential effects of prisms can be observed on actions (which are typically improved) and perceptual biases (which often remain unchanged). Here, we present a computational model capable of explaining some basic symptoms of neglect (line bisection behaviour), the effects of prism adaptation in both healthy controls and neglect patients and the observed dissociation between action and perception following prisms. The results of our simulations support recent contentions that prisms primarily influence behaviours normally thought to be controlled by the dorsal stream. PMID:25430546

  15. Structure of the conchiolin cases of the prisms in Mytilus edulis Linne.

    PubMed

    GREGOIRE, C

    1961-02-01

    The prisms in the shell of Mytilus edulis Linné are calcite needles. Their small size and their thin conchiolin cases distinguish them from the prisms of many other species of mollusks. These Mytilus prisms have been studied with the electron microscope. The material consisted of positive replicas of surfaces of the prismatic layer, etched with chelating agents, and of preparations of tubular cases from decalcified prisms which were compared with the conchiolin from decalcified mother-of-pearl of the same species. In the replicas, the cases appear as thin pellicles in the intervals between the prism crystals. Both the prism cases and the nacreous conchiolin, disintegrated by exposure to ultrasonic waves and sedimented on supporting films, appear in the form of tightly meshed, reticulated sheets, described as "tight pelecypod pattern" in former studies on nacreous conchiolin of Mytilus. The results show that in the shell of this species the same conchiolin structure is associated with aragonite in mother-of-pearl and with calcite in the prismatic layer. PMID:13708397

  16. STRUCTURE OF THE CONCHIOLIN CASES OF THE PRISMS IN MYTILUS EDULIS LINNE

    PubMed Central

    Grégoire, Charles

    1961-01-01

    The prisms in the shell of Mytilus edulis Linné are calcite needles. Their small size and their thin conchiolin cases distinguish them from the prisms of many other species of mollusks. These Mytilus prisms have been studied with the electron microscope. The material consisted of positive replicas of surfaces of the prismatic layer, etched with chelating agents, and of preparations of tubular cases from decalcified prisms which were compared with the conchiolin from decalcified mother-of-pearl of the same species. In the replicas, the cases appear as thin pellicles in the intervals between the prism crystals. Both the prism cases and the nacreous conchiolin, disintegrated by exposure to ultrasonic waves and sedimented on supporting films, appear in the form of tightly meshed, reticulated sheets, described as "tight pelecypod pattern" in former studies on nacreous conchiolin of Mytilus. The results show that in the shell of this species the same conchiolin structure is associated with aragonite in mother-of-pearl and with calcite in the prismatic layer. PMID:13708397

  17. Reacquisition deficits in prism adaptation after muscimol microinjection into the ventral premotor cortex of monkeys.

    PubMed

    Kurata, K; Hoshi, E

    1999-04-01

    A small amount of muscimol (1 microl; concentration, 5 microg/microl) was injected into the ventral and dorsal premotor cortex areas (PMv and PMd, respectively) of monkeys, which then were required to perform a visually guided reaching task. For the task, the monkeys were required to reach for a target soon after it was presented on a screen. While performing the task, the monkeys' eyes were covered with left 10 degrees, right 10 degrees, or no wedge prisms, for a block of 50-100 trials. Without the prisms, the monkeys reached the targets accurately. When the prisms were placed, the monkeys initially misreached the targets because the prisms displaced the visual field. Before the muscimol injection, the monkeys adapted to the prisms in 10-20 trials, judging from the horizontal distance between the target location and the point where the monkey touched the screen. After muscimol injection into the PMv, the monkeys lost the ability to readapt and touched the screen closer to the location of the targets as seen through the prisms. This deficit was observed at selective target locations, only when the targets were shifted contralaterally to the injected hemisphere. When muscimol was injected into the PMd, no such deficits were observed. There were no changes in the reaction and movement times induced by muscimol injections in either area. The results suggest that the PMv plays an important role in motor learning, specifically in recalibrating visual and motor coordinates. PMID:10200227

  18. Field evidence for fault controlled intrusion of blue-schist-bearing melange into an accretionary wedge, Island Mountain, California

    SciTech Connect

    Lamons, R.

    1985-01-01

    Two lithologic units of the Franciscan are well exposed along a loop of the Eel River at Island Mountain. They are 1) zeolite or lower grade lithic graywackes, and 2) a 0.5 km wide band of black shaly melange containing blueschist, chert, greenstone, metagraywacke, and a graywacke-hosted copper deposit. Sedimentary features were not observed in the melange. The graywacke was subdivided on the basis of presence or absence of sodium-cobaltonitrate stained K-spar. Field relationships suggest that the blueschist-bearing melange was emplaced along steep NW-dipping faults in an accretionary wedge. Mapping of S. Jewett Rock and SW Lake Mountain quadrangles show narrow anastomosing bands of the melange following NW-trending faults. East of this band, graywackes without K-spar are folded along NW/SE axes. No folds were found to the west. Other Melange bands pinch out into faults which juxtapose graywackes of different facies. The sheared melange bands are not folded and shale beds in the graywacke show little shear so the melange bands are unlikely to be sheared olistostromes. The areal extent of graywacke is about ten times that of melange shales. Assuming this pattern continues laterally and at depth, the amount of ductile material in the melange is far less than that assumed by Cloos (1982) in his flow model for melange. The ductile melange may have been forced upward by metamorphically produced volatiles, or as a result of relative plate motion. It originated at depth, moved up along the top of a subducting slab, plucking clasts, then splayed upward into pre-existing faults in the accretionary wedge.

  19. The effect of diagenesis and fluid migration on rare earth element distribution in pore fluids of the northern Cascadia accretionary margin

    USGS Publications Warehouse

    Kim, Ji-Hoon; Torres, Marta E.; Haley, Brian A.; Kastner, Miriam; Pohlman, John W.; Riedel, Michael; Lee, Young-Joo

    2012-01-01

    Analytical challenges in obtaining high quality measurements of rare earth elements (REEs) from small pore fluid volumes have limited the application of REEs as deep fluid geochemical tracers. Using a recently developed analytical technique, we analyzed REEs from pore fluids collected from Sites U1325 and U1329, drilled on the northern Cascadia margin during the Integrated Ocean Drilling Program (IODP) Expedition 311, to investigate the REE behavior during diagenesis and their utility as tracers of deep fluid migration. These sites were selected because they represent contrasting settings on an accretionary margin: a ponded basin at the toe of the margin, and the landward Tofino Basin near the shelf's edge. REE concentrations of pore fluid in the methanogenic zone at Sites U1325 and U1329 correlate positively with concentrations of dissolved organic carbon (DOC) and alkalinity. Fractionations across the REE series are driven by preferential complexation of the heavy REEs. Simultaneous enrichment of diagenetic indicators (DOC and alkalinity) and of REEs (in particular the heavy elements Ho to Lu), suggests that the heavy REEs are released during particulate organic carbon (POC) degradation and are subsequently chelated by DOC. REE concentrations are greater at Site U1325, a site where shorter residence times of POC in sulfate-bearing redox zones may enhance REE burial efficiency within sulfidic and methanogenic sediment zones where REE release ensues. Cross-plots of La concentrations versus Cl, Li and Sr delineate a distinct field for the deep fluids (z > 75 mbsf) at Site U1329, and indicate the presence of a fluid not observed at the other sites drilled on the Cascadia margin. Changes in REE patterns, the presence of a positive Eu anomaly, and other available geochemical data for this site suggest a complex hydrology and possible interaction with the igneous Crescent Terrane, located east of the drilled transect.

  20. Field evidence for contrasting origins of ash pellets, coated ash pellets, and accretionary lapilli: implications for the vertical structure of density currents and atmospheric ash plumes

    NASA Astrophysics Data System (ADS)

    Branney, M. J.; Brown, R. J.

    2012-12-01

    Field evidence from numerous sites reveals that adhesion of fine ash particles occurs in pyroclastic density currents as well as in lofted atmospheric plumes. Moreover, the type of aggregate in a deposit can help distinguish ashfall layers from thin, topography-draping ash deposits of pyroclastic density currents - a crucial distinction in hazard assessments. Ash aggregates additionally have potential to provide much-needed information on the little-understood vertical concentration-structure of density currents. The ashfall origin of ash-clusters and unstructured ash pellets is well established both from recent eruptions and occurrences in ashfall deposits. In contrast, there is growing evidence that some types of large, concentric-laminated accretionary lapilli grow during transport in pyroclastic density currents, as distinct from growing in lofted atmospheric plumes. On Tenerife, they occur matrix-supported within uppermost parts of ignimbrites, but are absent in the associated co-ignimbrite ashfall layers, even proximal to the ignimbrite. The ashfall layers contain only small, clast-supported unstructured pellets of fine ash, and it appears that the lofted co-ignimbrite plumes were not able to support the lapilli. Field relations of deposits on valley sides suggest that the scenario of a high-concentration density current with a buoyant co-ignimbrite ash plume may be over-simplified. They suggest, rather, that the concentrated part of the density current graded up into levels that were less-concentrated, more turbulent, hot, yet still dense enough to rush downslope. As ash pellets from the co-ignimbrite plume drop through the stratified pyroclastic density current, ash accretion is increasingly affected by the elevated temperatures, where reduced moisture levels inhibit adhesion of all but the finest ash particles to the growing lapillus, hence the development of fine-grained rims. As the lapillus descends to lower levels we infer that they heat up and harden